Production of industrial alcohol is an age old practice. But with time, the usage areas as well as production techniques have gone through a major transformation. Industrial alcohol is distilled ethyl alcohol (C2H5OH), normally of high proof, produced and sold for other than beverage purposes. It is usually distributed in the form of pure ethyl alcohol, completely denatured alcohol, especially denatured alcohol and proprietary solvent blends. Ethyl Alcohol is the common name for the hydroxyl derivative of the hydrocarbon ethane .Industrial alcohol is distilled ethyl alcohol normally of high proof, produced and sold for other than beverage purposes. Industrial alcohol finds its applications in many chemical industries, pharmaceutical industries, Ink Industries and various allied applications. Much of this alcohol is obtained synthetically from ethylene. However, its production from microbial fermentation using variety of cheap sugary substrates is still commercially important. The various substrates used for ethanol production are sugar crops such as sugarcane, sugar beet, sorghum, etc. provide a good substrate. Bye product of these crop processing, e.g., molasses, sweet sorghum syrup, etc. are the most common substrates. Cereals like maize, wheat, rice etc are also used for ethanol production. Distillation of industrial alcohol, which is normally not used for consumption, can be made in a two step process. The process of distillation is one with a slow dynamics making it essential to have a carefully planned and designed control system. Ethyl alcohol or ethanol ranks second only to water as the most widely used solvent in chemical industry and as these industries have expanded, so the demand for industrial alcohol has increased.
Some of the fundamentals of the book are base case production of alcohol, survey and natural alcohols manufacture, alcohol from wheat straw, alcohol from sacchariferous feed stocks, conventional process used in Indian distilleries, fermentation, distillation, continuous rectification and reflux ratio, alcohol recovery, quality of alcohol, steam economy, fuel oil separation, trihydric and polyhydric alcohols, coal gasification, methanol synthesis, coal gasification and raw gas purification, synthesis gas preparation, methanol synthesis and purification, badger conceptual design
This handbook on Industrial alcohol technology provides complete details on process and the technology used in the production of ethanol from various sugar crops and cereals and also briefs the different types of monohydric, trihydric and polyhydric alcohols. This handbook will be very helpful to its readers who are just beginners in this field and will also find useful for upcoming entrepreneurs, existing industries, technical institution, etc.
1. Alcohol from Corn
Base Case Production of Alcohol, Overall Material and Energy Flows, Grain Motor Fuel Alcohol Plant, Excursions on Feedstock Material, Sensitivity to Financial Parameters, Depreciation Schedule, Purchase Price of Corn, DOG By-product, Leveraged Capital, Investment Tax Credit, Background and Job Scope, Design Basis, Base Case, Excursions, Plant Capacity, Nature of Raw Material For Process, Corn Stover (Biomass) as Primary Boiler Fuel, Corn Processing By-products, Production of Motor Fuel Grade Alcohol, Base Case, Process Description, Receiving, Storage and Milling, Mash Cooking and Saccharification, Fungal Amylase Production, Fermentation (Batch), Distillation, Fusel Oil and Heads Removal, Evaporation and Drying of Stilage Residue, Alcohol Storage and Shipping, Ammonium Sulfate Storage and Shipping, Dry Grains Storage and Shipping, Coal Fired Boiler, Water Supply, Waste Water Treatment, Flue Gas Scrubber, 100 mm Gallon per year Alcohol Plant, Fixed Investment, Excursions on Feedstock Materials, Wheat, Process Description, Milo (Grain Sorghum), Process Description, Sweet Sorghum, Process Description, Environmental Impact, Air Emissions, Waste Water, Solid Waste, Noise, Labor and Employment Impact, Agricultural Production, Plant Labour, Agricultural Impact, Subsidies and Land Use, Improved Farm Income, Grain Supply and Price, Comments on Developing Technology, Grain Production, Grain Processing, Fermentation, Distillation, Animal Feed Processing, Cellulose Alcohol Development, U.S. Army-Natick Laboratories, University of California of Berkeley (Wilke), University of Pennsylvania (Humphrey) and General Electric Company, Purdue (Tsao), Gulf Oil Chemicals Co., Development Obstacles and Research Priorities, Grain Production Improvement, Grain and Residue Collection, Grain Processing, Fermentation, Distillation, Animal Feed, Agricultural and Forest Residues, Socio-economic Development, Gasohol Subsidy, Support Adjustment, Octane Improvement and Emissions, Plant Layout, Raw Materials and Chemicals, Utilities, Plant Personnel, Products and By-products, Department of Energy Washington, D.c., Grain Motor Fuel Alcohol Plant, Investment Cost Summary, Comments on Grades of Alcohol, Cost Differential to go from 190°Proof Spirits to 199° Proof Motor Fuel Alcohol, Cost Differential Between 199° Proof Motor Fuel Alcohol and 200° Proof Industrial Anhydrous Alcohol, Evaluation Procedure for Economic Analyses, General, Annual Operating Expense, Working Capital, Parameters Affecting Financial Analyses Inflation Environment, Depreciation Schedule, Federal, State, and Local Taxes, Investment Tax Credit, Discounted Cash Flow, Methods of Obtaining Capital, Production of Grain Motor Fuel Alcohol, Alternate Capacities, 10 mm Gallon Per Year Alcohol Plant, Fixed Investment, Financial Analysis, Alcohols Polyhydric, Reactions, Manufacture, Analysis, Health and Safety Factors, Uses
2. ALCOHOLS, HIGHER ALIPHATIC
Survey and Natural Alcohols Manufacture, Detergent Range Alcohols, Plasticizer Range Alcohols, Physical Properties, Chemical Properties, Shipment and Storage, Analysis, Specifications and Standards, Toxicological Properties, Manufacture from Fats and Oils, Hydrogenolysis Process, High Pressure Hydrogenolysis, Methyl Ester Hydrogenolysis, Fatty Acid Hydrogenolysis, Production of Unsatu-rated Alcohols, Uses of Detergent Range Alcohols, Surfactants, Cosmetics and Pharmaceuticals, Lubricants and Petroleum, Other Applications, Uses of Plasticizer Range Alcohols, Plasticizers, Other Plastics Uses, Lubricants, Fuels, and Petroleum, Agricultural Chemicals, Surfactants, Other Applications, Synthetic Processes, The Ziegler Process, Triethylaluminum Preparation, Chain Growth, Oxidation, Hydrolysis, Environmental Considerations, The Oxo Process, Process Technology, Olefin Sources, The Aldol Process, The Paraffin Oxidation Process, The Guerbet Process
3. ALCOHOL FROM WHEAT STRAW
Introduction, Summary and Conclusions, Process Description, Process Discussion, Cost Estimates, Batch Process Technology in Indian Distilleries , Definitions, Molasses, Total Reducing Sugars, Unfermentable Sugars, Fermentable Sugars, Brix, Polarisation (Pol.), Purity, Alcohol, Spirit's, Wort, Pitch or Bub, Wash, Sludge, Sediment, Reflux, Spent Wash, Proof Spirit, Calculation of Efficiency Data, Alcohol Production Processes, Synthetic Process, Alcohol from Starchy Materials (Grain Spirit), Scenario, Potential of Grain as Raw Material, Process Description, Raw Material Preparation, Liquefaction, Yeast Cultivation & Prefermentation, Saccharification & Fermentation, Alcohol from Sacchariferous Feed Stocks, Conventional Process Used in Indian Distilleries, Fermentation, Distillation, Continuous Rectification and Reflux Ratio, Alcohol Recovery, Quality of Alcohol, Steam Economy, Fusel Oil Separation, Absolute Alcohol
4. Monohydric Alcohols
Lower Saturated Acyclic (Aliphatic) Alcohols, Methyl Alcohol, Physical Properties, Chemical Properties, Ethyl Alcohol, Nonazcotropes, n-Propyl Alcohol, Isopropyl Alcohol, 1-Butanol, Isobutyl Alcohol, sec-Butyl Alcohol, Physical Properties, Chemical Properties, tert-Butyl Alcohol, Amyl Alcohols, C5H11OH, n-Amyl Alcohol, sec-Amyl Alcohol, 3-Pentanol, Active Amyl Alcohol, Isoamyl Alcohol, tert-Amyl Alcohol, Higher Saturated Acyclic (Aliphatic) Alcohols, Neopentyl Alcohol, sec-Isoamyl Alcohol, Acyclic Higher Alcohols, n-Hexyl Alcohol, Methyl Amyl Alcohol, Methyl Amyl Carbinol, 2-Ethylbutanol, n-Heptyl alcohol, 2-Heptanol, Chemical Properties and Toxicity, n-Octanol, 2-Octanol, 2-Ethylhexanol, Isooctyl Alcohol, Physical Properties, 2,2,4-Trimethyl-l-pentanol, Nonyl Alcohol, Diisobutyl-carbinol, Behenyl Alcohol, Lignoceryl Alcohol, Ceryl Alcohol, Montanyl Alcohol, Myricyl Alcohol, Melissyl Alcohol, Lacceryl Alcohol, Geddyl Alcohol, Unsaturated Acyclic (Aliphatic) Alcohols, Introduction, Health and Safety Factors, Uses, Unsaturated Alcohols, Vinyl Alcohol, Allyl Alcohol, Propargyl Alcohol, Crotyl Alcohol, Methylallyl Alcohol, Propargylcarbinol, Allylethyl Alcohol, 1-Penten-3-ol, 1-Pentyn-3-ol, Methyl Butynol, Reactions of the Hydroxyl Group , Reactions of the Triple Bond, Reactions of t tie Acetylenic Hydrogen, Reactions of the Hydroxyl Group and Triple Bond, 1-Hexen-3-ol, Leaf Alcohol, Hexynol, Methyl Pentynol, 4-Methyl-l-pentyn-3-ol, 1-Octen-3-ol, 2-Octyn-l-ol, Ethyl Octynol, Oleyl Alcohol, Citronellol, Geraniol, Linalool, Analogs and Derivatives of Alcohols, Analogs, Derivatives, Oxidation Products, Alicyclic Alcohols, Introduction, Cyclopropanol, Cyclobutanol, Cyclopentanol, Cyclohexanol, Ethynyl Cyclohexanol, Menthol, a-Terpineol, Borneol, Cholesterol, Ergosterol, Fenchyl Alcohol, Physical Properties, Chemical Properties, Araliphatic Alcohols, Benzyl Alcohol, b-Phenylethyl Alcohol, Styralyl Alcohol, Hydro-cinnamyl Alcohol, Benzhydrol, Triphenylmethanol, Cinnamyl Alcohol, Cuminyl Alcohol, Salicyl Alcohol, Phenylpropargyl Alcohol, Heterocyclic Alcohols, Furfuryl Alcohol, Tetrahydrofurfuryl Alcohol, Thenyl Alcohol, Hydroxymethylpyrrole
5. Trihydric and Polyhydric Alcohols
Trihydric Aliphatic Alcohols (Glycerols), General, Preparation, Properties, Uses, Glycerol, Occurrence, Production, Physical Properties, Grades of glycerin, Specific Gravity, Epoxy Compounds, Esters, 1,2,4-Butanetriol, Pentaglycerol, Hexaglycerol, 1,2,6-Hexanetriol, Higher Polyhydric Aliphatic Alcohols, Chemical Properties, Toxicological Properties, Uses, General, Physical Properties, Tetrahydric Alcohols (Tetritols), CH2OH(CHOH)2 CH2OH, Erythritol, d-and l-Threitol, dl-Threitol, Pentaerythritol, Pentahydric Alcohols (Pentitols), Ribitol, Xylitol, Preparation, d-Arabitol, l-Arabitol, dl-Arabitol, Hexahydric Alcohols (Hexitols), Allitol, Dulcitol, Sorbitol, Chemical Properties, Toxicity and Uses, l-Glucitol, d-Mannitol, l-Mannitol, Physical Properties, Chemical Properties, Toxicity and Uses, dl-Mannitol, d-Iditol, l-Iditol, d-Talitol, l-Talitol, dl-Talitol, Inositol, Heptahydric Alcohols (Heptitols), Perseitol, Volemitol, Glycero-gulo-Heptitol and D-glycero-D-ido-Heptitol, Octahydric Alcohols (Octitols), Polyvinyl Alcohol
6. METHANOL FROM COAL
General Discussion, Coal Gasification, Methanol Synthesis, Process Features, Dupont Feasibility Study, Preliminary Selection, Methanol Fuel Product, High Spot Process Evaluation, General Process Description, Environmental Considerations, Sasol Type Process Study, Coal Gasification and Raw Gas Purification, Synthesis Gas Preparation, Methanol Synthesis and Purification, Badger Conceptual Design, Introduction, Process Description, Economic Evaluation, Summary and Conclusions
Alcohol from Corn
PRODUCTION OF ALCOHOL
The alcohol plant is sized to produce
50 MM gal per yr of alcohol (motor fuel grade) from corn. The overall alcohol
product yield is 2.57
gallons per bushel of corn thereby requiring 19.43 MM bushels of corn
In addition to the alcohol product, the plant produces 117,111 T per yr
Distillers Dark Grains by product. Illinois coal which is to be used as
fuel for the plant.
The alcohol plant, in general, uses
existing process technology currently employed in grain alcohol plants.
plant operates as a continuous flow process, except for the
fungal amylase sections which are operated batch wise in order to allow
frequent sterilization of the equipment.
The distillation system employs a two pressure concept
significantly improves its steam economy. The two pressure concept is
other chemical processing fields and in industrial and beverage alcohol
production but has not, to our knowledge, been employed in a commercial
motor fuel alcohol distillery. This
process concept, along with other heat economy measures, results in a
steam usage of 31.7 lbs per gallon of alcohol. The distillation system
21.4 lbs per gallon of which 2.8 lbs per gallon is obtained as flash
from mash cooking.
All of the utility requirements, with
the exception or electricity, are produced within the boundaries of the
Water is obtained from a well field located close to the plant. The boiler burns
relatively low cost, high
sulfur coal. Flue gas from the boiler is used to dry the stillage
residue in producing
the Distillers Dark Grains (DDG) by product. Waste water is treated in
a two stage,
activated sludge, treatment facility. The sludge is dewatered and fed
water is recycled from a
two cell cooling tower.
Approximately one third of the plant
power requirement is obtained from steam turbines.
The coal fired boiler produces 600 psig 600°F
steam which is used to drive turbines for large energy users. The
exhaust the steam at 150 psig which is suitable for process
The corn is received, stored, and
milled in section 100. After milling, the feed material is
conveyed to Section 200 for mash cooking and starch conversion to sugar
(Saccharification). The enzyme, fungal amylase, required for
is produced in Section 300. The saccharified mash is cooled and sent to
fermentation, Section 400. The sugars in the mash are fermented to
alcohol in the
batch fermenters. The fermented mash is then transferred to Section 500
alcohol recovery and dehydration. The stillage residue from the alcohol
stripper rectifier (Section 500) is sent m Section 600 for dry grains
The alcohol product and by products are delivered to Section 700 for
The three major energy inputs are
corn, coal, and electricity. The two primary outputs are alcohol and
Dark Grains. A breakdown of electrical power and steam usage is shown
Another method for determining the
thermal efficiency is to consider the energy required to produce the
and credit for the energy required to produce the DDG on the bases of
as an additional energy input item. In Illinois, the average usage is
Btu bu of corn which includes energy for field preparation, harvesting,
fertilizer supplies, transportation and other miscellaneous usages.
A third method of calculating the
thermal efficiency is to include the total thermal energy contained in
and dried grains. The method yields an overall plant efficiency of 68.9
In considering the production of motor
fuel grade alcohol, the most logical primary feedstock choice is corn,
is produced voluminously in major growing areas of the United States
producers of industrial grade alcohol prefer corn because of its
The Department of Energy requested
that we evaluate feedstock materials other than corn. The objective is
compare the required alcohol selling price for the excursions to the
(corn) alcohol selling price. The alcohol selling price is the market
required to recover production cost and to return to the investor a
discounted cash flow interest rate of return.
Wheat and milo can be processed in
essentially the same equipment as the corn feed material. Sweet sorghum
requires new front end equipment, more steam generating capacity, and
storage and handling facilities; consequently the investment is
higher than for the base case. The sweet sorghum excursion is designed
as the feed material during the dead season. (We assumed sweet sorghum
harvested for 165 days of the year). This becomes very expensive since
portion of the plant is idle during either season. In addition, the
sorghum raw material is more expensive than the corn; and the
Grain by product from sweet sorghum is less valuable than the corn feed
materials by product.
Another alternative would be to design
the sweat sorghum plant to process double the sweet sorghum feed
during the active season, and concentrate approximately one half the
storage and use during the dead season. This alternative was not
detail because it became obvious that the investment would be higher
combination corn, sorghum alternative due to the high cost of doubling
of the front end equipment, and energy use would increase.
The wheat excursion results in a
relatively high alcohol selling price; whereas the milo excursion
the lowest alcohol selling price. Milo production in this country is
substantially less than corn, and a major new market for milo could
milo market price to increase. This would reduce the advantage for
of alcohol from milo.
Contract EJ 78 C 01 6639 of August 31,
1978 between the Department of Energy and Raphael Katzen Associates was
to permit development of realistic estimates of investment, production
and sales prices for motor fuel alcohol from grain. This assessment was
based on the most advanced current fermentation and distillation
which has been proved on a commercial basis.
With a base case defined for
production of 50 million gallons per year of motor fuel alcohol (199°
from corn, and with optional feedstock variations on wheat, milo and
sorghum; grass roots site requirements and definitions were developed
the Department of Energy and Raphael Katzen Associates. A nominal
Illinois location was selected for the estimate, which would be
any of the feed materials except sweet sorghum, where a southern
be advantageous from the raw material supply standpoint.
Variations of plant size, and effect
on investment and operating costs, were evaluated for facilities of 10
gal per yr alcohol capacity and 100 million gal per yr alcohol capacity.
The facility was defined as a grass roots
facility, complete with all utilities and services required for
operation of a
grain alcohol plant. In addition to the alcohol product, it was agreed
animal feed byproduct was essential to the operation, not only from a
of product sales, but also to minimize waste disposal problems. Feed
for this type of grain alcohol plant residue are already well
the animal feed processing section was designed to yield a conventional
marketable product defined as Distillers Dark Grains (DDG).
With coal as the essential fossil fuel
(thus to eliminate the need for oil or natural gas) efforts were made
minimize energy requirements and maximize the ratio of fuel output
(alcohol) versus the fuel input value (coal). An option for use of corn
as a fuel was also estimated, in efforts to eliminate the use of fossil
However, in either of these cases, it was still found necessary to
electrical energy, and energy charges for fossil fuel production of
electrical energy were made against the operation.
In the fermentation of sugar produced
from the starch contained in grain, certain extraneous materials other
ethyl alcohol are produced. These are fusel oils, a complex mixture of
molecular weight alcohols, and yeast (saccharomyces). In Table 7 are
assumptions used for this study with regard to fusel oil formation.
lists the assumptions made with regard to the formation of yeast.
ALCOHOLS, HIGHER ALIPHATIC SURVEY AND NATURAL ALCOHOLS
The monohydric aliphatic alcohols of
six or more carbon atoms are generally referred to as higher alcohols.
Historically, the higher alcohols, particularly those of 12 or more
atoms, were derived from natural fats, oils, and waxes and were called
alcohols; but now similar alcohols are widely available from synthetic
processes using petrochemical feedstocks (qv). Although the natural and
synthetic alcohols are used interchangeably for many applications, for
applications the distinction still remains. The higher alcohols can be
separated into the plasticizer range alcohols, generally 6 11 carbon
the detergent range alcohols, 12 or more carbon atoms. There is,
considerable overlap in use. Production of higher alcohols in North
Europe, and Japan in 1985 was about 2,600,000 tons and United States
was 35percent of that total. About three fourths of the U.S. output was
plasticizer range alcohols, which are used primarily as ester
plasticizers (qv) and lubricants. The detergent range alcohols are used
as sulfate, ethoxy and ethoxysulfate derivatives in a wide variety of
detergent, and surfactant applications.
Most higher alcohols of commercial
importance are primary alcohols; secondary alcohols have more limited
uses. Detergent range alcohols are apt to be straight chain materials
made either from natural fats and oils or by petrochemical, processes.
range alcohols are more likely to be branched chain materials and are
primarily by petrochemical processes. Whereas alcohols made from
and oils are always linear, some petrochemical processes produce linear
alcohols and others do not.
Detergent Range Alcohols. Natural or
synthetic detergent range alcohols are usually described as middle cut
carbon atoms) or heavy cut (16 18 carbon atoms), corresponding to the
distillation fractions of coconut alcohol from which these alcohols
derived. Because middle cut alcohols are preferred for most detergent
applications, manufacturers maximize this production through feedstock
(natural alcohols), or by manipulating processing conditions (synthetic
alcohols). The co product light cut (6 11 carbon atoms) and heavy cut
are also valuable products. Only a small percentage of detergent range
are sold as pure single carbon chain materials.
The higher alcohols occur in minor
quantities primarily as the wax ester (ester of a fatty alcohol and a
acid) in many oilseed and marine sources. Free alcohols octacosanol,
and triacontanol, C32H66O, have been isolated in very small amounts
sugarcane and its products. Oil from the sperm whale is rich in wax
hexadecanol, octadecenol, and eicosenol; this oil was formerly a major
source of these alcohols. The oil of the North Atlantic barracudina
contains 85percent wax esters that consist mainly of hexadecanol and
octadecenol. Minor amounts of alcohols having 12 26 carbon atoms have
found in both ancient and recent marine sediments, probably having
in ocean marine life. Wool grease from sheep also contains higher
wax esters, and is a minor commercial source of alcohol. The seeds of
jojoba which grows in the North American desert give an oil which
esters of eicosenol and docosenol and the natural waxes such as
and candelilla wax contain wax esters with alcohols of 26 34 carbon
Although higher alcohols could be obtained from any of these plant
saponification of the esters, they are not commercially important
Table 1 provides physical property
data for selected pure alcohols. The homologous series of primary
alcohols exhibits definite trends in physical properties for each additional CH2 unit
boiling point increases by about 20°C, the specific gravity increases
0.003 units, and the melting point increases by about 10°C in the lower
the range and about 4°C in the upper end. The water solubility
increasing molecular weight and the oil solubility increases. In
higher alcohols are soluble in lower alcohols such as ethanol and
in diethyl ether and petroleum ether. The solubility of water in 1
1 octanol is appreciable, but drops off rapidly as alcohol molecular
increases. Enough solubility remains, however, to make even 1
slightly hygroscopic. Mixtures of alcohols, such as 1 octadecanol and 1
are considerably more hygroscopic. Below C12 the normal alcohols are
colourless, oily liquids with light, rather fruity odours. At room
pure 1 dodecanol solidifies to soft, crystalline platelets and the
form of higher molecular weight alcohols progresses from these soft
to crystalline waxes. Although 1 dodecanol has a slight odour, the
homologues are essentially odourless. The secondary and branched
alcohols are oily liquids at room temperature and have light, fruity
They are soluble in alcohol solvents and diethyl ether, and also show
affinity for water as molecular weights increase. The members of this
not have well defined freezing points; they set to a glass at very low
temperatures. Physical properties are often ill defined because of
in obtaining pure samples.
The higher alcohols undergo the same
chemical reactions as other primary or secondary alcohols. Similar to
chemicals having long carbon chains, however, reactivity decreases as
weight or chain branching increase. This lower reactivity and
decreased solubility in water and in other solvents means that more
reaction conditions, or even use of different reaction schemes as
shorter chain alcohols, are generally required.
Detergent range alcohols are available
in 208 L (55 gal) drums ot approximately 160 kg or 23.000 L (6000 gal)
trucks, in tank cars of 75.000 L (20,000 gal) containing about 60,000
in marine barges. The tank trucks and cars are usually insulated and
with an external heating jacket; the barges have coils for melting and
the alcohols. High melting alcohols such as hexadecanol and octadecanol
also available as flaked material in three ply, polyethylene lined 22.7
lb) bags. Detergent range alcohols have a U.S. Dept. of Transportation
classification as nonhazardous for shipment. The perfume grade
as specially purified octanol and decanol, are available in bottles and
plasticizer range materials are
available in 208 L drums, 23,000 L tank trucks. 75,000 L tank cars, and
marine barges. Because of low melting points, most of these materials
require transports having heating equipment. Bulk shipments are usually
described by the commercial name of the material, such as methyliso
for 4 methyl 2 pentanol. The names hexyl octyl, or decyl alcohol are
freight descriptions for the linear or branched alcohols of
carbon number. Linear and branched alcohols of 6 9 carbon atoms, and
containing them, are classified as combustible for shipment by the U.S.
because of their low flash points. Alcohols of 10 carbons and above are
classified as non hazardous.
The higher alcohols are not corrosive
to carbon steel, and equipment suitable for handling solvents or
also suitable for the alcohols. However, special storage conditions are
needed to maintain alcohol quality. Lined carbon steel tanks having
blankets to exclude both moisture and oxygen are recommended for
detergent range alcohols. Preferred storage temperature is no higher
above the alcohol melting point and repeated cycles of melting and
must be avoided. Low pressure steam is generally used for heating; for
melting hexadecanol and octadecanol, hot water can be used in order to
exposure to high temperature heating surfaces. Although they are
considered quite stable, alcohols which are stored either for long
time or under improper conditions can undergo such subtle changes as
deterioration of colour, increase in carbonyl level, or a decrease in
stability. It is sometimes preferable to store high melting alcohols as
in bags at ambient temperature rather than melted in a tank at higher
To prevent rusting and moisture pickup
resulting from the hygroscopic nature of plasticizer range alcohols,
should be protected from moisture by such devices as a drying tube on
or a dry air blanket; nitrogen is usually not needed because ambient
temperature is adequate for these lower melting materials. In general,
plasticizer range alcohols are more storage stable than the detergent
alcohols. However, to avoid the danger of fire resulting from the low
points of plasticizer range alcohols, tanks should be grounded, have no
interior sources of ignition, be filled from the bottom or have a
extending to the bottom to prevent static sparks, and be equipped with
Because the higher alcohols are made
by a number of processes and from different raw materials, analytical
procedures are designed to yield three kinds of information the carbon chain length
combining weight, of the alcohols present; the purity of the material;
presence of minor impurities and contaminants that would interfere with
subsequent use of the product. Analytical methods and characterization
alcohols have been summarized.
For the detergent range alcohols,
capillary gas chromatography, fast, accurate, and simple to use, is by
most useful method for determining composition and purity. By the
of the capillary stationary phase, carbon chain distribution and the
unsaturated, chain branched, or secondary alcohols, as well as the
minor materials such as esters and hydrocarbons, can be determined.
From the HV the combining weight can
be calculated for subsequent chemical reactions. Carbonyl content is
especially for those alcohols manufactured from aldehydes by the oxo
It is often expressed similarly to HV as
the mg of KOH equivalent, to the carbonyl oxygen in 1 g of sample.
expressed in terms of the equivalent weight percent of acetic acid, is
determine the quality of the alcohol, as are moisture and APHA colour.
the detergent range alcohols, tests which measure colour stability in
presence of sulfuric acid are employed to predict the colour changes
occur in subsequent reactions utilizing acid catalysts.
Additionally, analytical determinations
such as odour, chloride level, hydrocarbon content, and trace metal
are required for specific uses.
Most of the detergent range alcohols
used commercially consist of mixtures of alcohols, and a wide variety
products is available. Table 2 shows the approximate carbon chain
composition of both the commonly used mixtures and single carbon
typical properties are given in Table 3. Although only even carbon
available from natural fats and oils and the Ziegler process, the
of the oxo process for linear alcohols has made odd carbon alcohols a
commercial reality, albeit with some chain branching. Commercial
these latter alcohols contain both odd and even numbered chain lengths.
major production of detergent range alcohols is in the 12 18 carbon
Fats and Oils
Fats and oils from a number of animal
and vegetable sources are the feedstocks for the manufacture of natural
alcohols. These materials consist of triglycerides glycerol
esterified with three moles of a
fatty acid. The alcohol is manufactured by reduction of the fatty acid
functional group. A small amount of natural alcohol is also obtained
commercially by saponification of natural wax esters of the higher
such as wool grease.
The carbon chain lengths of the fatty
acids available from natural fats and oils range from 6 22 and higher,
a given material has a narrower range. Each triglyceride has a random
of fatty acid chain lengths and unsaturation, but the proportion of the
acids is fairly uniform for fats and oils from a common source. Any
triglyceride or fatty acid may be utilized as a raw material for the
manufacture of alcohols, but the commonly used materials are coconut
kernel oil, lard, tallow, rapeseed oil, and palm oil, and to a lesser
soybean oil, corn oil and babassu oil. Coconut and palm kernel oil are
primary sources of dodecanol and tetradecanol; lard, tallow, and palm
the primary sources of hexadecanol and octadecanol. Producers of
alcohols typically make a broad range of alcohol products having
chain lengths. They vary feedstocks to meet market needs for particular
and to take advantage of changes in the relative costs of the various
The first commercial production of
fatty alcohol in the 1930s employed the sodium reduction process using
ester feedstock. The process was used in plants constructed up to about
but it was expensive, hazardous, and complex. By about 1960 most of the
reduction plants had been replaced by those employing the catalytic
Hydrogenolysis Process. Fatty alcohols
are produced by hydrogenolysis of methyl esters or fatty acids in the
of a heterogeneous catalyst at 20,700 31,000 kPa (3000 4500 psi) and
in conversions of 90 98percent. A higher conversion can be achieved
rigorous reaction conditions, but it is accompanied by a significant
To prepare methyl ester feedstock for
making fatty alcohols, any free fatty acid must first be removed from
or oil so that the acid does not react with the catalyst used in the
alcoholysis step. Fatty acid removal may be accomplished either by
by converting the acid directly to a methyl ester. Refining is done
chemically, by removal of a soap formed with sodium hydroxide or sodium
carbonate (alkali refining), or physically, by steam distillation of
acids (steam refining). In the case of chemical refining, the by
is acidified to give a fatty acid and these foots are used as animal
upgraded for industrial fatty acid use. The by product fatty acid from
refining is of a higher grade than acidifed foots and is used directly
industrial fatty acid or as animal feed. In either case, the fatty acid
also be converted to the methyl ester find used as additional alcohol
feedstock. Refined oil is dried to prevent the reaction of water with
catalyst during alcoholysis.
Alcoholysis (ester interchange) is
performed at atmospheric pressure near the boiling point of methanol in
steel equipment. Sodium methoxide, CH3ONa, the catalyst, can be
prepared in the
same reactor by reaction of methanol and metallic sodium, or it can be
purchased in methanol solution. Usage is approximately 0.3 1.0 wt
Monohydric alcohols can be considered
to be hydrocarbons in which one of the hydrogens is replaced by an OH
If the hydrocarbon consists of an
unbranched carbon chain, the equivalent primary alcohol is called
indicated by the prefix n.
Depending on the location of the OH
group along the hydrocarbon chain, and the number of replaceable
the same carbon atom, it is possible to have three types of alcohols.
ACYCLIC (ALIPHATIC) ALCOHOLS
CH3OH (methanol, wood
alcohol, carbinol, Columbian spirit, wood spirit) is the simplest of
saturated monohydric alcohols, with a molecular weight of 32.04. At
temperatures, this alcohol is a colourless, neutral mobile, flammable,
liquid with a characteristic odour.
Methyl alcohol is rarely found
naturally in the Free State e.g., trace amounts found in essential oils
fermented liquors. However, it exists in the plant kingdom as a part of
organic substances, one of which is responsible for the name, wood
Methyl comes from the Greek words for wine and wood, krasi and xulon,
indicating the original use and source. Several plant oils contain
esters; oil of wintergreen has methyl salicylate, C6H4(OH)
COOCH3, and oil of jasmine contains methyl
COOCH3. Alkaloids and natural pigments also
contain the methyl
radical in the form of complex ethers. The natural product (wood
obtained from hard wood is a crude solvent with an offensive odour and
impurities. By contrast, synthetic methanol is an extremely pure
product with a
characteristic odour and a water white colour.
The first chemist to recognize
methanol is said to be Robert Boyle in 1661, who found a neutral
the liquor obtained from wood distillation. Taylor in 1812 gave
methanol and called this substance pyroligneous ether, and Dumas and
isolated and identified the alcoholic compound in 1834. Berthelot first
synthesized methanol in 1858 by saponification of methyl chloride.
acid was the only commercial source of methanol for several decades,
but in the
last 35 years or so, pressure synthesis from carbon oxides and hydrogen
superseded the wood distillation method.
When hardwoods such as maple, birch,
beech, and oak are heated in the absence of air to temperatures of 160
thermal decomposition takes place and produces non condensable gases, a
distillate (known as pyroligneous acid), wood tar, and charcoal. The
distillate is refined by extraction and/or distillation to produce
methanol, and acetone.
Most of today s methanol is produced
by the catalytic reduction of either carbon monoxide, carbon dioxide,
carbon oxides plus hydrogen in the presence of zinc and chromium
conditions range from 100 600 atmospheres and 250 400°C. Commercial
Corporation became the first American company to produce and market
methanol in 1927.
Other manufacturing methods of lesser
importance are as follows direct
of hydrocarbons, saponification of methyl chloride, and preparation of
formate from sodium methoxide and carbon monoxide followed by low
Physical Properties. The more
important physical properties of methyl alcohol are given in Table 2.
compound burns with a blue flame and no soot to CO2 and H2O, and may
explosive mixtures with air. The first stage of methanol oxidation is
formaldehyde (HCHO), which then proceeds to formic acid (HCOOH),
(HOCOOH), and finally to carbon dioxide and water, Methyl alcohol is
poison under federal and state statutes, and is quite toxic to humans.
Methanol is a highly polar compound
and is the closest alcohol in structure to water when considered as an
derivative (R OH) of it. Consequently, methanol is a powerful solvent
substances, including synthetic coatings and adhesives like
ethyl cellulose, and polyvinyl butyral; natural gums and resins, which
shellac, rosin, lauri, and manila; dyes; and most organic liquids.
Among the many important physical
properties of methanol, only a few will be shown in graphic form. The
pressure of pure methanol between 10 and 240°C has been given by
a logarithmic plot against the reciprocal of absolute temperature.
presents vapour pressure data for methanol, ethanol, isopropanol, l
and 1 butanol in terms of the above coordinates in order to obtain data
Since methanol is so frequently used
in industry as an aqueous solution, studies by Carr and Riddick have
condensed and presented in Table 3. These physical properties are also
importance for analyzing simple mixtures.
The wide usage of methanol as an anti freeze
gives practical importance to the freezing point curve shown in Figure
data that correspond to percent by weight make up the lower curve,
methanol has a density of less than 1. Therefore, methanol is more
antifreeze when formulated on a weight percent basis rather than by a
numerically equivalent volume percent basis.
Acetone, benzene, carbon disulfide and
chloroform are some of the more than 110 compounds with which methanol
constant boiling mixture (Horsley). Methanol does not form an azeotrope
hence it may be recovered from aqueous solutions by distillation.
Chemical Properties. The chemical
activity of methyl alcohol is closely related to other saturated
particularly with respect to reactions of the hydroxyl group. However,
methyl group deviates on occasion from typical alkyl group reactions
is unique in having only one carbon atom. Examples are presented for
important reactions of methanol.
Commercially, these reactions are
conducted in a continuous flow system in the presence of a dehydrating
catalyst, such as alumina gel, at an elevated temperature and pressure.
ratio of the three amines depends upon the ratio of the reactants and
reaction conditions. Pressure distillation is employed to separate the
The formation of di and trimethylamine may be suppressed by recycling
products, by introducing water into the feed, or by the use of a large
of ammonia. It may be increased by recycling monomethylamine.
Toxicology. The principal
physiological effect of methanol on human beings is damage of the
nervous system with a specific deleterious effect on the optic nerve.
Additional effects may also occur depending on the exposure; these
changes in the kidney, liver, heart, and other organs. The human body
eliminates methanol very slowly. A widely accepted belief is that the
of methanol is due mostly to the metabolites, formaldehyde and formic
which are powerful nerve poisons in their own right. Oral ingestion of
leads to physiological effects which are similar to those arising from
inhalation, but symptoms are likely to appear sooner and to be more
nature. An oral dose of 2 4 oz is usually fatal, although 1 2 oz has
reported to be a lethal dose in a number of cases. This picture is
complicated in that effects on humans are not constant small amounts of methanol
will not affect some
individuals and seriously harm others. The vapour toxicity of methanol
compared to many common solvents at low concentrations. At the 1958
of Governmental Industrial Hygienists, a maximum allowable
concentration of 200
ppm for continuous 8 hr per day working exposure was adopted as the
safety. This same limit was adopted for toluene, amyl acetate, and
acetate. However, a person may be subject to an excess of methanol
take an excess internally without a severe initial reaction. Even if
is not lethal, blindness occurs in many instances. Consequently,
labeled a poison under federal and state statutes.
A brief exposure to high
concentrations of methanol vapours may develop acute poisoning. For
1000 ppm in air may cause irritation of the eyes and mucous membranes;
may produce stupor or sleepiness; and 50,000 ppm may result in profound
narcosis in 1 2 hrs and will probably lead to death. Repeated exposure
concentrations for brief periods, or a continuing exposure to low
for a long time may produce chronic poisoning. Again, this effect is
the accumulation of methanol in the human system caused by slowness in
Skin contact with methanol, in
general, gives no adverse effects if gross exposure is avoided.
Methanol has an
additional physical action on skin since it is a solvent for natural
and can induce a drying effect by dissolving fats and oils from the
Methyl alcohol finds numerous
applications, as a cleaner of steel, metal and plastic surfaces; as a
in glass cleaners and special dry cleaners; and as a reducing agent in
cleaning, brass annealing, and soldering fluxes.
Formation of gas hydrates and ice in
natural gas pipelines is inhibited by this alcohol. Methanol coagulates
rubber, and is used to manufacture dipped rubber goods. Miscellaneous
applications are as a taxidermy agent, and an ingredient of embalming
is probably the best known of all alcohols, with such common names as
grain alcohol, wine spirit, Cologne spirit, and ethyl alcohol. This
a colourless, neutral, mobile liquid of molecular weight 46.07, which
agreeable but pungent odour, and a sharp burning taste.
Ethyl alcohol resembles methanol in
that it is seldom found in nature. These rare occurrences are in the
seeds of Heracleum giganteum and Heracleum spondylium, in the urine and
of men who have consumed an excessive amount of alcoholic beverages,
and in the
urine of diabetic people.
As mentioned previously, intoxicating
liquids obtained from the fermentation of saccharine plant juices were
the ancient Egyptians and Greeks, and contained ethanol in impure form.
not until the late eighteenth century that the purification of mixtures
pure anhydrous product was achieved. Saussure, in 1808, determined the
constitution of ethanol. However, it was not until 1899 that Berthelot
synthesized ethyl alcohol by reacting ethylene with sulfuric acid, and
hydrolyzing the resultant ethyl sulfuric acid with boiling water to
sulfuric acid and ethanol.
The above equations indicate that the
starting material for the fermentation process may be any raw material
containing hexose sugar, or materials that can be transformed into
sugars. France and Belgium use sugar beets; Germany utilizes potatoes;
European countries have converted sulfite liquor and sawdust, while
sugar, and cane molasses are the most popular in the United States.
wood flour require the conversion of cellulose to fermentable sugars by
hydrolysis, but grains can be converted by the action of malt. The
source of fermentable sugar is blackstrap molasses which is a by
sugar cane manufacture, and contains 50 to 60percent sugar by weight.
United States used to import considerable molasses from Cuba, but in
years a hostile climate between these countries has halted the import
of Cuba s
molasses. Hence, its disposition as a mixed animal feed has become
in other countries for reasons of economics. Most of the industrial
produced by fermentation in the United States comes from blackstrap
of which Puerto Rico has become an important source.
Trihydric and Polyhydric Alcohols
ALIPHATIC ALCOHOLS (GLYCEROLS)
with three or more
hydroxyl groups are called polyhydric alcohols or polyols. Just as we
generic name of glycol applied to the dihydric alcohols, in a similar
the trihydric alcohols are named glycerols after their most important
special grouping of straight chain alcohols containing four or more
groups on an equivalent number of carbon atoms have the name of sugar
and are discussed in a later section on Polyhydric Alcohols.
are derived from
hydrocarbons by the substitution of three hydroxyl groups for three
atoms which had been linked to different carbon atoms.
number of carbon atoms increases,
so does the number of isomeric trihydric alcohols. With the additional
configurations, any combination of primary, secondary, and tertiary
groups can be obtained. Furthermore, the alcohol groups may be oxidized
keto, and carboxylic acid groups, thereby leading to 19 possible
of the four different functions.
of routes leading to
the formation of trihydric alcohols have been studied, and several
methods are illustrated below. Specific methods for 1, 2, 3
be presented in a later section.
physical, chemical, and
toxicological properties of the glycerols will be illustrated by using
1, 2, 3 propanetriol
as an example. Because of the great industrial importance of 1, 2, 3
it will be referred to as glycerol, and its properties will be
some detail in the early portion of the section on trihydric aliphatic
alcohols. The typical chemical reactions of glycerol will generally
other trihydric alcohols where they involve the reactivity of one, two,
three hydroxyl groups.
the applications of
the trihydric alcohols are included in the more than 1500 uses of
(1,2,3 propanediol) e.g., as a humectant solvent, plasticizer, a
pharmaceuticals, and as a derivative employed in plastics, coatings,
explosives, and foods.
1, 2, 3
CH2OHCHOHCH 2OH (glycerol, glycerin, glycerine) is a clear, water
trihydric alcohol of molecular weight 92.09. It exists as a viscous,
hygroscopic, odourless liquid with a sweet taste.
is a component part of
all animal and vegetable fats and oils (triglycerides). A Swedish
Scheele, discovered glycerol in 1779 when he saponified olive oil with
to make lead plaster. He found a clear, sweet tasting syrup had formed
surface of the mixture, and he call this liquid the sweet principle of
ChevreuI, in 1813, recognized ester like glycerol derivatives in fats
and discovered the saponification process. He studied the trihydric
further, and gave it its present name of glycerol (derived from the
glykeros meaning sweet). Pelouze, Berthelot, Lucca, and Wurtz later
the chemical composition as that of a trihydric alcohol which could be
separated from animal and vegetable fats. Tilghman discovered that
could be produced by splitting fats with heat. A current practice is to
term glycerol for the pure chemical compound, whereas glycerin denotes
commercial grades with variable glycerol contents. The spelling
considered incorrect because the ending ine applies to a base, and
not a base.
is present as a triglyceride in all animal and vegetable fats and oils,
rarely found in a free state in these fats unless rancidity or
has occurred during storage or handling. Oils from vegetable sources
coconut, olive, and soybean yield larger amounts of glycerol that the
molecular weight animal fats, which include tallow, mutton, and lard.
is also widely found in nature as the triglyceride in fatty substances
lecithin (found in eggs, soybeans, and brain, nerves, liver, kidneys
animal organs) and cephalin (found in brain, liver, and other organs as
The major portion of the worlds production of glycerol comes from the
manufacture of soaps by the saponification of fats and oils, (of which
is a coproduct), and from the hydrolysis of fats and oils into fatty
aqueous liquid stream or
layer is called glycerol sweet water and may contain up to 20 percent
Molten fatty acids are neutralized with lime, then the mixture is
After preliminary evaporation to a half crude state, excess lime is
precipitated by carbonates or sulfates. followed by filtration and
to a saponification crude that contains about 88percent glycerol.
purification by vacuum distillation yields the assorted commercial
as high gravity, dynamite USP, etc.
development in the
refining of glycerol sweet water is the use of ion exchange resins in
columns. The good quality (low ion content) of a glycerol stream from
splitting process is the main reason for the commercial success of the
sources of glycerol from fats and oils, and these come from the
ester type chemicals such as the methyl and ethyl esters of fatty
from fatty alcohols made by the sodium reduction process. Both appear
declining sources, since modern industrial practice favours the
fatty acids directly from fats and oils by splitting, followed by
conversion to esters or fatty alcohols by catalytic methods.
production of glycerol by
fermentation of sugars has only been studied in the United States on a
plant scale, although it has been a production operation in Europe for
addition of sodium sulfite
to the fermenting liquid ties up acetaldehyde and favours glycerol
The crude glycerin obtained by this method is very poor in quality;
consequently, expensive refining methods would be required to compete
with the saponification, splitting, or synthetic methods of manufacture.
production of synthetic
glycerol on a commercial scale was a major chemical achievement of the
decades, and earned Shell Chemical Company the
Engineering Achievement Gold Medal Award in 1948. This important
was stimulated to some extent by the impact of synthetic detergents on
laundry soap market, whose introduction subsequently led to a reduced
processing of fats and oils, thereby producing less glycerin for
route has the
advantage of producing allyl alcohol as an intermediate. The
along with allyl chloride, is widely used chemicals with their own
process (2) is less
lime consumming than the first (I), and can be employed to yield
epichlorohydrin by treating the mixed chlorohydrins with calcium
procedures result in a
dilute solution containing about 5percent glycerol plus sodium
yield of dilute glycerol is about 90percent when based on aliyl
a 20 fold concentration has to be achieved, it is essential that all
steps be carried out with considerable care to reduce impurities to a
The solution is concentrated to about 80percent glycerol in multiple
evaporators, and sodium chloride is removed by centrifugation. Vacuum
distillation and further desalting gives a crude distillate which is
coloured, and generally unsatisfactory as a finished product.
colour bodies and some of the odorous materials are easily extracted
raffmate with a hydrocarbon solvent. Steam vacuum distillation of the
removes light esters and chlorides as a top cut, and yields glycerol of
purity or better from a second column. Synthetic glycerol produced in
manner meets the specifications of the United States Pharmacopeias.
Point. The boiling
point of pure glycerol at atmospheric pressure (760 mm Hg) is 290°C.
decomposition takes place at this temperature, boiling points at
pressures have been determined and calculated. Duhrings rule is found
to the boiling point of glycerol water solutions when they are compared
similar reference liquid such as water.
points of various
compounds, and mixtures of glycerol with this component, are given in
Azeotropes and a number
of non azeotropes are listed. A ternary mixture, ethyl alcohol, water
is particularly useful to distill anhydrous ethanol, since the affinity
glycerol for water prevents distillation of an alcohol ,water
addition of hygroscopic salts further improves the efficiency of this
procedure, and provides the basis for manufacturing absolute alcohol.
glycerol is highly hygroscopic and can absorb about 50percent of its
water. This ability to attract moisture and hold it is one of the most
properties of glycerol, and is the basis for its applications as a
as a conditioning and plasticizing agent. Aqueous solutions of glycerol
concentration will gain or supply moisture until a concentration is
which is in equilibrium with the moisture of the air. Several
have been made of the relative
humidity maintained over aqueous glycerol solutions, and
Figure 2 is a
composite plot of percent
relative humidity versus per cent glycerol by weight in water solution
temperate range of
20 100°C. The plot can be used in two ways (1)
an open dish of
aqueous glycerol in a large space will lose or gain moisture until its
composition is in equilibrium with the relative humidity of the
(2) an open dish of aqueous glycerol in a cabinet or other enclosure of
space will produce a relative humidity that corresponds to the glycerol
concentration. The reservoir of
glycerol solution must be sufficiently large, of course, so that
it can take up or supply the required amount of moisture.
refractive index n2D0 of pure glycerol is
1.47399. This determination can be easily made with good
precision, ind is quite sensitive to dilution with water. However,
specific gravity is a little more precise and supersedes this method
for analytical purposes.
and Solvent Power.
Glycerol, with its three hydroxyl groups, has solubility
similar to those of water and the simple aliphatic alcohols.
trihydric alcohol is
miscible in all proportions with water, lower alcohols and glycols, and
It has a limited miscibility with ether, acetone, ethyl acetate,
aniline. Glycerol is practically insoluble in hydrocarbons, chlorinated
hydrocarbons, higher alcohols, and fatty oils. However, it will
organic and inorganic compounds to some extent. Aliphatic and aromatic
hydrocarbons show an improved miscibility with glycerol as they gain
and amine groups. The introduction of alkyl groups, as may be expected,
in a decreasing miscibility with glycerol. Table 4 shows the
miscibility of a
variety of organic solvents with glycerol.
thermal conductivity of glycerol solutions increases with rising
as well as with increasing water content.
Pressure. The vapour
pressure of glycerol is lower than one would expect from its molecular
as a result of the molecular association characteristic of alcohols,
other polar compounds. Since many important applications of glycerol
of its relative nonvolatility, this property has been determined by
investigators for both the pure compound and aqueous solutions.
pressure of 100percent
glycerol is about 0.00018 mm Hg at 20°C and about 0.195 mm Hg at 100°C.
glycerol is dissolved in
water, it causes a greater reduction in vapour pressure than can be
molar concentration. This effect is due to the formation of hydrates.
pressure for aqueous glycerol solutions may be calculated by Duhrings
through the use of an allied reference liquid, such as an aliphatic
The high viscosity
of glycerol is one of its distinctive properties and is the basis of
applications. Segar and Oberstar worked with 99.97percent pure glycerol
Ostwald viscometers to obtain viscosity data over a 0 to 100°C
range, in concentrations from 0 to 100percent. Some of their data are
in Figure 3, which consists of a family of curves at
several temperatures showing increasing viscosity with a rise
in glycerol concentration and a fall in temperature. Glycerol polymers
di and polyglycerol
higher viscosities with increasing molecular weight.
general, electrolytes increase the viscosity of anhydrous glycerol and
solutions, but several compounds have the opposite effect, e.g.,
iodide, ammonium iodide and bromide, rubidium chloride and bromide, and
chloride and nitrate. The viscosity of glycerol rises with increasing
glycerol is super cooled, its
viscosity increases gradually until the temperature range of 70 to
reached. In this region, glycerol changes from a viscous liquid to a
glassy form called the vitreous state. and its physical constants
those of crystalline glycerol rather than liquid glycerol.
taste of glycerol is
predominantly sweet, although tests made by Cameron show it to be
sweet than sucrose. When concentrated glycerin is taken into the mouth,
produces a sensation of warmth.
mentioned previously, glycerol is the simplest trihydric alcohol and
two primary and one secondary hydroxyl groups. The molecule is
hence, the two CH2OH
identical in their properties. The chemical nature of glycerol is
characteristic of primary and secondary alcohols, but the presence of
hydroxyl groups contributes to additional reactions and derivatives as
to mono and dihydric alcohols. In general, the primary hydroxyl groups
reactive than the secondary hydroxyl. Even though a reaction has been
on one hydroxyl group, there is some reaction with the second and third
hydroxyl groups before the most reactive position has been completely
As a result of this generalization, glycerol derivatives are almost
obtained as mixtures containing isomers and products of different
(1,2,3 propanetriol), is commonly called glycerol and the ol ending indicates the
presence of a hydroxyl
group. The term glycerin is applied to technical grades which contain
and organic impurities.
METHANOL FROM COAL
the one stage gasification
process represents only one family of processes for producing synthesis
which can ultimately be utilized to produce methanol. A brief
the characteristics of various types of one stage gasification
presented in Table 1 and Figure 2. However, any one of the many
capable of converting coal into a synthesis gas of acceptable
in principle, a viable link to the production of methanol. A brief
the alternative routes that may be considered is presented in Figure 3.
is which methanol is ultimately
produced from synthesis gas is depicted schematically in figure 4. As
is typical for low
conversion processes of this nature, a substantial recycle stream is
to obtain high yields. Of further note are the entry points of feed at
ends of the converter. The lower point is, in reality, a bypass stream
allows fine adjustments of flow through the reactor and thus enables
temperature control in the converter bed. This control is vital to
5, methanol production by
partial oxidation of methane is depicted schematically. The oxidation
may or may not contain a catalyst. Catalytic agents claimed to be
are iron, nickel, copper, palladium, etc., their oxides, mixtures of
oxides, mixtures of their oxides and metals, aluminum sulfate, and
major methanol synthesis
processes that are marketed today are the ICI process (Imperial
Industries), the Lurgi low pressure process (Lurgi Corporation), and
the CPI Vulcan
process (Vulcan Cincinnati).
Process (a) and (b) is coal
sized to 1½ to 4 inch mesh lock hopper fed to piled bed on grate.
Koppers Totzek Process is pulverized
and steam introduced through burners; particles entrained in gas
Winkler Process (a) and (b) is
pulverized coal screw fed to fluidized bed.
The U Gas
Process is pulverized coal
pretreated in fluidized bed and gasified in fluidized bed.
gasification processes considered
in the preliminary screening are those that have been in commercial use
Europe, Asia, and Africa for making town gas and synthesis gas (usually
ammonia production) Lurgi (moving bed), Koppers Totzek (entrained flow)
Winkler (fluidized bed) and the Texaco partial oxidation process which
commercially demonstrated with a variety of feedstocks from natural gas
vacuum resid and petroleum coke.
operated a 10 tpd pilot unit
for a series of runs with different coals during the past few years,
and it is
reported that a 200 tpd commercial scale unit is being refitted for
coal in a
German plant site. It is DuPonts opinion that the Texaco process is
sufficiently demonstrated to meet the requirements of this study.
Spot Process Evaluation
information obtained, high
spot estimates were made for chemical
grade methanol from coal processes based upon Koppers Totzek, Lurgi,
Winkler coal gasification units. The
amount of coal and oxygen required to produce a nominal 5,000 tpd of
grade methanol, the thermal efficiency and the
capital investment were
estimated and the results Shown in Table 2.
Texaco processes have higher
thermal efficiency than the other two processes because of the above
operating pressures and lower requirement for compression.
Lurgi appear to require the
lowest investment although the differences are well within the accuracy
technology is well adapted to
eastern bituminous coals as is Koppers Totzek; there is some question
ability of Lurgi and Winkler gasifiers to handle swelling caking coals
trouble free manner.
gasifiers handle larger throughputs
per unit than Lurgi gasifiers and this reduces the number of gasifiers
following sections a more detailed
consideration of process scope and definitions will be presented to
basis for estimating capital requirements. It should be emphasized that
although it is DuPonts opinion that the assumption of Texaco gasifiers
other process units in this study will result in representative results
production of methanol fuel from high sulfur eastern bituminous coals,
recognized that for a given installation with specific coal, other
and processes should be evaluated to achieve optimum design.
A grid (8
squares) over the hopper
tramp material from entering the hopper. If the grid becomes plugged,
must be stopped to remove such material.
Communication between the receiving hopper and the
required to regulate train speed and stop start.
Stage 2 Coal
is fed from the day pile at the rate of 1,600 tph through two vibrating
feeders. At this rate, the 10,000 ton day pile can be transferred to
storage pile(s) in 6¼ hours (one shift or less).
A recording belt scale in the transfer
conveyor between the feeders and the tripper gives a check on the
delivered by each unit train and tonnage into storage piles.
tripper belt conveyor receives the
coal from the transfer conveyor and delivers it to either one or both
belt conveyors. The tripper and the stacker belt are mounted on a
traveling tower permitting two storage piles to be formed giving a 15
supply of coal for the boiler and gasifier section. Tripper tower may
stationary to discharge coal at a given point or travel to blend the
arrived coal with the coal already in storage.
Stage 3 From
each of the piles, vibrating feeders are placed on 40 foot centers to
the coal at the rate of 400 tph. These
feeders are actuated in groups of four for the purpose of controlling
of withdrawal from a pile, and discharge to a 36 inch recovery belt
which, in turn, feeds a primary (ring mill) crusher. A belt scale in
recovery conveyor controls the variable feeder.
blending from both piles is required,
coal may be recovered from both piles at regulated lower tonnages. Each
mill crushes 8 0
coal at 3 rate of 400
tph and reduces it to ¾ 0. A 36 inch belt conveyor
from each ring mill
delivers to a common surge bin to end Stage 3.
Stage 4 From
the surge bin, ¾ 0 coal is withdrawn by a variable rate vibrating
feeder at a nominal
24 tph onto a 24 inch belt conveyor for delivery as boiler fuel. A
second 24 inch
belt conveyor is furnished to deliver wet char (60percent solids) to
boiler. Both of these conveyors, discharge into a double shaft paddle
from which this boiler fuel drops into a boiler fuel surge bin.
Stage 5 From
the surge bin, coal is withdrawn through two regulating feeders at the
179 tph each and discharged into two rod mills. This rate is 15percent
than is required for
section; therefore, once the system is full, one mill could be down 7
minutes per day or both down 3 hours, 36 minutes per day.
mill requires a one hour shutdown
period every third day to clean out thin and broken rods and then add
9,000 pounds of new rods. The shutdown time permits this servicing as
other maintenance in the grinding section.
introduced at the feed end of the
rod mills along with the coal for wet grinding. The amount of water is
regulated by a density controller located at the discharge of each mill
a slurry of 50 to 54percent solids by weight. This slurry with its
ground to 14 mesh 0 is delivered to two sumps from where it is pumped
ball mills where the solids are reduced to 80percent 200 mesh. Trommel screens at the
discharge of these
mills prevent balls or other relatively large solids from continuing in
flow of slurry.
controller at the discharge of
each ball mill adds water, if needed, to maintain the ball mill
slurry at 50 to 54percent solids by weight. This completes the
the coal slurry in this open grinding circuit. Slurry from each ball
into a sump and is pumped to two steel tanks having the capacity for
24 hour slurry supply ahead of the gasification section. Each tank is
with agitators to keep the slurry in a ready condition.
centrifuges (plus a standby) receiving
¾ 28 mesh from the
solids to the ash conveyor and effluent to thickener. A lime slaker is
to neutralize an acid ash slurry from the flue gas cleanup process
25,000 lb per hr of 200 mesh solids, 480 gpm water and 100 to 200 lb
per hr of
H2SO4 at 140ºF.
This solution has pH of 2 and is delivered to the ash
building. The lime
slaker is automatic
and neutralizes the slurry to a pH of 7 prior to releasing it for
foot diameter thickeners are
provided complete with bridges, rakes, drives and lifting mechanisms.
thickeners operate together receiving the aforementioned screen
dryer effluent and slurry totaling 1,480 gpm water plus 14 tph solids.
Clarified water from the thickeners shall contain not more than ½
solids by weight.
(plus a standby) deliver
underflow from the thickeners, delivering to one disc filter (plus one
filter) from which the solids are discharged to the ash conveyor and
effluent to the pump sump along with the overflow from the thickeners.
clarified water pump (plus a standby) returns this water back to the
gasification section for reuse. The net water excess is consumed in the
slurry preparation (Stage 5).
centrifuged ash, filtered ash, and possibly grit from the lime slaker
delivered at about 52 tph on a belt conveyor to a steel silo from
which it is loaded out into unit train cars.
suppression and/or collection devices
are provided at the receiving hopper, through tunnels, sample building,
points, loading points, crushers
and surge bin ahead of the rod mills. Two concrete lowering tubes are
the discharge points of the belt conveyors feeding the day pile to
excessive dusting and a telescopic chute with automatic controls is
the discharge of each traveling stacker belt to aid in dust prevention.
Gasification and Air Separation. Coal
slurry from the slurry storage tank is pumped to a slurry surge tank.
surge tank the slurry is preheated (preheat will reduce the oxygen
requirement). Oxygen is produced at the air separation plant operating
psig. 6,330 tpd of 99.5percent oxygen is produced and compressed to 935
(by centrifugal compressors). Air cooling is used in the inter coolers
water cooling is used in the turbine exhaust steam condensers.
(50 to 55 weight per cent coal)
is then pumped to the Texaco gasifiers via booster pumps and
charge pumps. The slurry is mixed with O2 and enters the combustion
zone where partial
oxidation occurs at 800 psig according to the following reaction
majority of the sulfur is converted to
some to COS. The nitrogen in the coal is converted to free nitrogen
traces of NH3 and HCN. The ash is melted
due to the high
temperature of the reaction. It is critical that the gasification
exceed the melting point of the ash sufficiently to yield a free
slag. The slag is assumed to leave the gasification section at 2300°F.
normally true that the ash with high calcium content will have lower
temperature. Therefore, by adding small quantities of CaO or other
agents to the coal slurry, the slagging temperature may be reduced. In
cases this procedure will not be necessary.
synthesis gas flows from the flame chamber
to the slag separation section where gravity separation occurs. The
drops to a wet bottom and is washed away. About 5percent of the carbon
feed is carried away with the synthesis gas as an unburned char
to 60percent ash.
synthesis gas is quenched by sour
water from the shift. There
energy penalty because this water will be consumed in the shift section
will eliminate the need for injection of live steam to the shift
(except for control purposes). The
quench step should result in less expensive material of construction,
erosion and scaling from reduction in the T in the waste heat exchanger
increase in the gas volume.
of the slag passes from the
gasification section to the slag quench section. The quench operation
is a semi
continuous process with a cycle time of about 15 to 17 minutes. In normal operation, the
cycles are timed so
the quench section of one gasifier is discharged while the others are
filled with slag and water.
utilizing the cyclic discharge the flow rate is large enough to wash
slag from the bottom of the gasifier.
quenched gas from the slag separator
enters a waste heat exchanger and is cooled to 633ºF by generating
576°F steam. The 633°F exit temperature has been determined by heat and
material balances on the entire gas cooling system in which a gas
of 50percent water vapour at saturation is assumed to exit the
gasifier system. This specification is set by the design
of the shift
then flows to a three stage dust
removal section in which adiabatic saturation is also reached. The
content of the 633°F gas will increase in the saturation process to
volume water vapour in the gas. The bulk of the dust is removed in the
saturation process. The residual dust is collected in the high energy
scrubber followed by a final cleanup using a wash tray. The makeup
added to the scrubbing cycle in the wash tray section.
slurry is withdrawn from the
quency scrubber with a maximum of 10percent solids slurry. The liquid
the quench section is maintained by bleeding a side stream from the
cycle which contains about 1percent slurry. The liquid level in the
cycle is controlled by the makeup of preheated sour water coming from
liquor withdrawn from the quench
section is cooled to 170°F against the thickener overflow. After cool
pressure is reduced and it is stripped with CO2 rich gas from the acid gas
At a temperature of 130°F it then enters the thickener. Due to
the thickener the temperature is reduced to 120°F, and the underflow
concentration is expected to be in the range of 25 to 30percent. The
is pumped to a rotary vacuum filter from which a wet char containing
water is discharged and conveyed to the steam plant as a fuel.
filtrate combines with the thickener
overflow and is reheated to 410°F and reinjected to the wash tray of
scrubbing section. Some excess of sour water leaves the system as a
purge stream from the thickener overflow to the slag disposal sump.
liquor from the gasifier
underflow and the dusty liquor from the scrubber underflow are stripped
with CO2 rich gas from the acid gas
treatment unit. The
overhead gas from the stripper is preheated from 130º to 220°F by
psig steam and then incinerated in the steam plant. By heating this
energy penalty on the boiler is decreased, and also corrosion in the
line is prevented.
Chemicals cobalt molybdenum
catalyst has been assumed for this study. Synthesis gas leaves the
section at 430°F and 770 psig, and has a steam to dry gas ratio of 1 1.
one sixth of this gas is bypassed around the shift reactor for control
purposes, while the remaining gas is preheated to 50*F above the
the overall thermal efficiency
of the process, it is imperative that the mode of heat recovery from
reactor effluent gas be done in a very efficient manner.
water, condensed as a result of this
cool down and heat recovery, is separated and recycled for synthesis
and scrubbing. An additional 73,600 Ib per hr knocked out at 130°F is
on level control to the wet grinding mills.
Treating Selective H2S
Removal Unit Synthesis
gas treating is accomplished in two stages. In the first stage, H2S is
selectively removed with respect to CO2 and COS, and the treated gas
leaving the H2S
has a total sulfur content of 210 ppm. This results in the off gas stream
to sulfur plant having an H2S
concentration of 23 mol per cent. In the second stage, residual COS and
portion of the inlet CO2 are removed yielding a
treated methanol synthesis gas containing 10 mol
per cent CO2 and less than 1 ppm total
there are several other
competitive physical solvent processes in the market, for this study
Chemical Corporations Selexol process was chosen. To meet the maximum
size requirement imposed by shipping as well as from operational
viewpoint, the entire treating plant has been divided into two
gas leaving the shift at 715
psig and 130ºF enters the H2S
absorber where it is contacted counter currently with lean
solution presaturated with CO2 from CO2 absorber. Due to the higher
solubility of H2S
CO2 in the solvent only
about 20percent of the inlet CO2 is
absorbed along with almost 100percent removal of H2S. To
minimize the amount of CO, CO2 and H2 losses from the H2S
stripper overhead, rich solution is
flashed in three successive stages and the flashed vapours are
recompressed and recycled back to the absorber after cooling.
rich solution from the third stage
is pumped to the top of the H2S
stripper, where stripping is accomplished
using 100 psig steam. Stripper reboiler duty is minimized by heating
solution to 275°F against the lean solution from the stripper bottom.
CO2 Removal Unit Desulfurized
gas is cooled before being contacted with chilled lean solution at 22°F
CO2 absorber. Lean solution from
chilled to 20°F using propane refrigerant before being combined with
solution from CO2 stripper bottoms. The lean
circulation is controlled to give a very close equilibrium at the
bottom which allows the CO3
concentration in the residue gas to be held at the 10 mol
cent level desired for the low pressure methanol synthesis process.
solution from absorber bottoms is let
down to 275 psia through a hydraulic turbine which provides part of the
required for driving the lean solution pump. Flashed vapours are
combined with the inlet gas, thus minimizing CO and H2 losses from CO2 stripper overhead. Flashed
rich solution is
further let down to 16 psia and acts as a refrigerant before being
using dry nitrogen from the air separation plant. The stripping rate is
yield COS content below 1 ppm in the final product gas.
CO2 rich gas is unsuitable from
standpoint for venting to atmosphere. Hence, it is compressed and sent
dusty liquor before being routed to the boiler for incineration of
Synthesis and Fractionation. The
synthesis and fractionation areas produce 5.496 tpd of fuel
grade methanol (95 wt percent methanol). ICIs low pressure
methanol synthesis technology was assumed in the design of this unit.
gas at 680 psig and 85°F from
the treating unit is passed through the desulfurizer drums. Each drum
two packed beds of activated carbon granules which act as a sulfur
the methanol synthesis catalyst.
drums are designed to operate on stream for
three days. At the end of this period one drum is taken off stream
fresh bed is put on line. The spent carbon is regenerated with steam
then returned to service.
desulfurizer drums the gas enters
the synthesis makeup compressor and is compressed to 1,542 psig. A
steam turbine using 1,175 psig, 925°F steam exhausting to 3½ inch Hg
is used to drive the
makeup compressor. The discharge gas from the compressor is combined
synthesis recycle gas and cooled in an air cooler to 130°F.
gas is divided into two equal
streams and then sent to two parallel synthesis loops each consisting
synthesis converter, heat exchange train, and recycle compressor, in a
the gas is further divided with a portion of the gas being sent as
the converter and the remainder being sent as feed to the converter. In
to achieve the temperature necessary for reaction to methanol, the feed
first passed through the converter feed preheater, where the gas is
hot reactor effluent.
preheated feed gas enters the top of
the converter vessel and flows downward through several catalyst beds
converter outlet. At the exit of each catalyst bed, cold quench gas is
to control the inlet temperature of the next catalyst bed.
gas contains about 5.5 mol per
cent methanol together with large amounts of unreacted CO, CO2, and H2 inerts such as N2, argon,
and some quantities of by products
such as water, dimethyl ether and higher alcohols.
separate the unreacted gases from the
product methanol, the converter outlet gas is cooled in a heat
train. The resulting two phase mixture from the cool down train is
the unreacted gases are sent to the recycle compressor and the
containing about 73 mol per cent methanol and 25 mol per cent water is
the fractionation unit, where the water content is reduced to about
and low boilers such as dimethyl ether and unreacted gases are taken
gas from the treating unit leaves the H2S
stripper reflux accumulator and
enters the inlet scrubber where any entrained sour water is knocked
concentration in the feed is only 23 mol per cent, the bypass type
configuration with three stages has been selected. In this
of the acid gas is oxidized in the reactor furnace with a
quantity of air. The hot combustion products are cooled in a waste heat
generating saturated 105 psig steam.
gas is combined with the acid gas which bypassed the combustion step
recycle SO2 rich gas stream from the
flue gas cleanup unit
and the mixture is heated to 450°F before entering the first converter.
important that H2S
to SO2 ratio at the converter inlet
be maintained at
2 to 1 for maximum conversion efficiency.
takes place in the presence of
activated alumina Catalyst. To ensure hydrolysis of COS in the feed,
12 inches in the catalyst bed contains Co Mo catalyst. All the sulfur
the converter is condensed by cooling the reactor effluent gas. The
gas is again heated up to 425°F before entering the second converter.
more conversion occurs and the sulfur formed is condensed by cooling
reaction gas to 340° F.