functions and considers some factors pointing to heavier future consumption.
T
h e d e m a n d in the petroleum refiningindustry for chemicals and allied prod
ucts is increasing in magnitude and variety.
Principal reasons for this are (1) The in
creasing amount of crude processed, (2) the war-accelerated development of new cata
lytic processes adapted to the manufacture of new or improved products, (3) recovery and utilization of hydrocarbon gases for
merly burned as fuel, (4) the resort to
"marginal” crudes which require heavier chemical treatment of their products, (5) growing application of additives to improve the performance of gasolines and lubri
cants, (6) exchange of information, among refiners during the war, which has led to wide adoption of processes requiring chemicals.
Petroleum refining is no longer a matter of crude distillation, thermal cracking and treating with sulphuric acid and caustic.
More chemicals from petroleum, more pure hydrocarbons, more "tailor-made” products, are being manufactured. Research and de
velopment is absorbing an increasing per
centage of company appropriations. Re
finers are gaining technological mastery over petroleum and in the process are consuming
a greater variety of chemicals than ever before.
Refining may be divided broadly into four phases with respect to the principal uses of chemicals. These phases are (1) Treatment and distillation of crude and sub
sequent fractionation of its products, (2) alteration of the molecular structure of products of fractionation, (3) use of chem
icals and allied materials to blend with or to treat the products of phases (1) and (2) for improvement of quality or protection of equipment, (4) chemical conditioning of tremendous quantities of water re
quired for condensing, cooling and steam.
CONSUMPTION SURVEY In 1942 the Petroleum Administration for War surveyed the chemical requirements of the refining industry. The survey covered the 12-month period ending October, 1941, and the results, therefore, indicate the nor
mal consumption of chemicals immediately preceding the war. Table I shows the prin
cipal chemicals used. Leading the list is sulphuric acid. Widely used in prewar years for treating gasolines, distillates and
lubricating oils, this acid enjoyed an ac
celerated demand during the war from the sulphuric acid alkylation process. The total sulphuric acid consumption during the period covered was actually higher than the figure shown, as refiners manufacturing their own acid reported a consumption of 70,900,000 lb. of sulphur, the major por
tion of which went into the production of acid.
Next to sulphuric acid in volume of re
quirement is clay. Prior to Pearl Harbor, clay, either as it came from the beds or after acid treatment, was used principally for the filtration of lubricating oils and fuel oils and to a lesser degree in the catalytic cracking of gas oils. A certain amount was used in the treatment of cracked gasolines:
During the war the use of treated clay ex
panded because of its utilization as a crack
ing catalyst in the manufacture of base stock for aviation gasoline.
Sodium hydroxide, third in the list, is, like sulphuric acid, a "work horse” in petro
leum refining. It has been and continues to be used throughout the industry for the neutralization of acid treated products, re
moval of sulphur compounds from gaseous
CHEM ICA L & M ETALLUR GICAL E N G IN E E R IN G • J A N U A R Y 1 9 4 6 • 1 3 9
• J A N U A R Y 1 9 4 6 • C H EM IC A L & M E T A L L U R G IC A L E N G IN E E R IN G
and liquid hydrocarbons, treatment of water and many other services.
in 1941) of gasolines manufactured.
After Pearl Harbor, the needs for some chemicals, relative to their previous use, ex
panded considerably. The main expansion occurred, of course, among chemicals util
ized in production of aviation gasoline or its components. Table II shows the esti
mated consumption of chemicals required in eight refineries of major coippanies in 1944. The consumption figures are weighted in accordance with the average daily crude throughput of each plant, the average for the group being about 45,000 bbl. per day.
These plants were either manufacturing components for 100 octane aviation gasoline or were making the finished product. The plants reported no consumption of solvents except cresylic acid, commonly used for solvent dewaxing and extraction of lubricants, indicating that their lubricants were pro
duced by other processes. On the basis of one barrel of crude charged, the require
ments of the eight refineries showed a marked' increase over the average consump
tion for the entire country in 1941, with respect to the following leading chemicals:
hydrofluoric acid, sulphuric acid, bauxite, aluminum chloride and tetraethyl lead fluid.
Typical wartime chemicals include hy
drofluoric acid, which had no significant place in refining prior to 1942 but which has become a major cherhical used in the hydrofluoric acid alkylation process for the manufacture of alkylate, a high-octane com
ponent for gasoline. Bauxite, another ma
terial relatively little used before the war, is also used in the alkylation process. Alu
minum chloride, which formerly had rather restricted uses, jumped into national im
portance in the war as the catalyst for iso
merization, principally in the conversion of normal butane to isobutane, one of the raw materials for alkylation. Sulphuric acid was consumed in greater amounts by reason of the construction of alkylation plants utiliz
ing the sulphuric acid process. Consumption of tetraethyl lead rose during the war be
cause of its use, averaging over 4.0 c.c. per gal., in aviation gasoline and in smaller quantities in other military gasolines.
CHEMICAL PROCESSING With reference to the arbitrarily desig
nated four phases of refining in which chem
icals afe employed, the first— distillation of crude and subsequent fractionation of straight-run products— utilizes appreciable amounts of ammonia and caustic soda in those instances where crudes containing sig
nificant percentages of magnesium chloride and hydrogen sulphide are processed. Re
finers vary in their application of these chem
icals and encounter different results depend
ing on the precise nature of the impurities solution for removal of hydrogen sulphide.
Anhydrous ammonia is injected into the vapor lines from three naphtha fractiona- tors to minimize corrosion in condensers.
Caustic and ammonia requirements per bbl.
of crude charged have been, respectively, 0.2 lb. and 0.04 lb.
Alteration of the rdolscular structure of the intermediate products of refining in
volves a number of processes requiring chem
icals and allied products. Foremost among these processes are thermal and catalytic cracking, alkylation, catalytic polymerization, butane isomerization and the manufacture of butadiene. Catalysts, the principal chem
icals consumed, are regenerated, but losses of. catalyst ultimately occur by physical loss from the equipment and systematic rejec
tion of catalyst when regeneration is no longer profitable.
Thermal cracking obviously does not re
quire a catalyst. However, when the oils being cracked contain much corrosive ma
terial, such as hydrogen sulphide, other sul
phur compounds or unstable chlorides, chemicals to nullify the effects of these trouble makers are frequently used. Corro
sion of equipment cost refiners many mil
lions of dollars yearly, and has been the sub
ject of numerous investigations by chemists and engineers. The cracking of oils of high sulphur content, such as gas oils and resi
duals from W est Texas and New Mexico crudes, is generally performed with the aid of neutralizing chemicals to protect equip
ment which is not sufficiently corrosion-
stance the lime consumption amounted to Large quantities o f sulphuric acid, aluminum trihydrate and sodium silicate solution are used by Socony-Vacuum Oil Co., Inc., Paulsboro, N. J., in this 50
ton per day synthetic bead catalyst plant
Table I — P rin cip al P re w ar Chemical Requirem ents of the Refining Industry
between 6,000 and 7,500 lb. per day. Some refiners have also refluxed their cracking unit evaporators with lime-bearing bubble tower bottoms.
In catalytic cracking the consumption of catalyst (basically, silica-alumina) is found to vary considerably in commercial practice.
Regeneration of spent catalyst by periodic oxidation is, of course, the rule in the Fluid, Iloudry and Thermofor processes, but, in time, the catalyst reaches the point where continued regeneration does not pay. In ad
dition some catalyst is lost mechanically from the cracking units through mishaps of operation, attrition of catalyst and start
ing and ending periods of operation. W ith
out regard to types of process involved, each of which has shown a rather wide range of catalyst consumption under different cir
cumstances, catalyst requirements have varied
Hydroforming, the process used during the war in petroleum refining to manufac
ture synthetic toluene, utilizes a dehydro- genating oxide type of catalyst in fixed beds which are periodically regenerated by burn
ing off the deposited carbonaceous matter.
Catalyst consumption is reported to be in
the vicinity of 0.2 to 0.4 lb. per bbl. of naphtha charged to the hydroforming unit.
Much the same general considerations affect
ing the consumption rates for catalytic crack
ing apply to hydroforming.
ACID ALKYLATION
The two alkylation processes of present commercial importance are those utilizing hydrofluoric or sulphuric acid as the cata
lyst. In the alkylation procedure- isobutane is combined with one or more of several olefins, notably butylene, to form a high- octane motor fuel. The hydrofluoric acid process brings the isoparaffin and the olefins into contact in the presence of liquid an
hydrous hydrofluoric acid, which is subse
quently recovered by distillation and used again in the reactor. During the war the consumption of this acid was reported as ranging around 1.5 lb. of acid per bbl. of alkylate manufactured by the process. Much of this was in the form of physical loss by leakage from equipment, although the formation of organic fluorides inevitably ac
counted for a small part of the loss. Opera
tion of alkylation units under severe condi
tions to expand production, and the use of unsatisfactory feed stocks for the same purpose, were additional factors. Produc
tion of alkylate by the hydrofluoric acid process reached about 60,000 bbl. per day early in 1945. Subsequent improvements in alkylation equipment have been made, re
ducing acid leakage. A large oil company
declared a short time ago that it was manu facturing alkylate at a hydrofluoric acid con sumption of only 0.7 to 1.0 lb .“per bbl. of alkylate. In addition to the acid, hydro
fluoric acid alkylation units utilize bauxite, Or alumina in some instances, both for dry
ing the feed gases and for removing traces of organic fluorides from vapor streams after the reaction. This was the major use of bauxite in petroleum refining during the war.
The sulphuric acid alkylation process uses an acid of 96 to 98 percent initial strength.
The acid, through sustained contact with the inflowing isobutane and olefin feed gases, gradually declines in strength and is gener
ally regarded as spent when an acidity of about 90 percent is reached. Acid consump
tion is governed by various factors such as reaction temperature, character of the feed gases and other operating variables. The range of consumption when butylenes domi
nate in the olefin gases has been from 1.0 to 2.0 lb. of fresh acid per gal. of alkylate, or between 42 and 84 lb. per bbl. In addi
tion to acid, caustic solution is ordinarily used to scrub the feed gases for removal of mercaptans and other objectionable im
purities.
ted the sulphuric acid alkylation process partly because they could use the spent acid for treating gasoline, kerpsene and lubric
Table II— W artim e Chem ical Consumption of Eight R efin eries
Crushed lim e and soda ash are used in this 100,000 gal. per hr. Cochrane fced- water treating unit for high pressure boilers at Shell’s Wood River plant ants. In some instances the rejected acid
is immediately reconcentrated and again used for alkylation.
Catalytic polymerization, one of the main
stays in the manufacture of 100-octane avia
tion gasoline, combines refinery butylenes to make an iso-octane material which is then hydrogenated to iso-octane. When employed to produce a blending agent for motor gaso
line the process commonly utilizes propylene as well as butylenes to secure a greater yield processing conditions that prevail influence the life of the catalyst, which has been seen to vary considerably. However, a company having long experience with the process has encountered ultimate catalyst consumption rates of between 0.3 and 0.4 lb. per bbl, of polymer produced. These rates were ob- • served in polymerizing mixed butylenes.
The isomerization of normal butane was practiced on a large scale during the war years for the purpose of furnishing isobutane needed in the manufacture of alkylate. Iso
complished at an aluminum chloride con
sumption rate of approximately 0.4 lb. per bbl. of isobutane, although rates vary.
Principal chemicals required in the man
ufacture of butadiene from petroleum are the catalysts and the solvents, notably am- moniacal cuprous acetate, for separating the butadiene product from other gases. Such chemicals are used whether or not the raw charge stock is butane or butylene. The catalysts belong, of course, to the group of oxides of metals such as chromium or molyb
denum, capable of dehydrogenating hydro
carbons. Catalyst consumption in the Standard Oil Co. (New Jersey) butylene de
hydrogenation process has ranged from 0.06 to 0.17 lb. of catalyst per gal. of butadiene.
IMPROVING PRODUCTS The third phase of refining operations, using chemicals to remove undesirable ma
terials from refinery products and to impart special performance characteristics to those products, is featured by the use of many different chemicals and can be but briefly summarized. Tire removal of objectionable materials by chemical treatment is one of the major aspects of refining. An example is the treatment of gasolines, particularly those manufactured by cracking processes or those which contain high percentages of sulphur or its compounds. As a general rule gasolines are treated to remove or render
innocuous sulphur compounds, gum-forming constituents and, to a decreasing extent, color-forming agents. Some straight-run gaso
lines are lightly treated if they contain ob
jectionable quantities of sulphur materials.
Components in gasolines which cause
dis-are being turned out at the rate of some 2 million bbl. per day, of which over half is cracked material, the magnitude of the treating involved can be grasped. Roughly 40 percent of the crude processed in the United States is converted into gasoline.
Until the accelerated use of other treat
stituents varies greatly, depending on the nature of the raw gasoline, strength of acid and the degree of refining desired. Much straight-run gasoline is not acid treated at all, although frequently given a small caustic wash. On the other hand acid treatments of from 1.0 to over 10.0 lb. per bbl. are necessary with cracked gasolines or those containing a high percentage of sulphur compounds. A common practice is to utilize sulphuric acid from gasoline treating for the treatment of heavier oils. Acid treat
ment regularly calls for the neutralization of acid traces by scrubbing the product with caustic solution. Although no statistics on the total quantity of caustic consumed for this purpose are available, the amount is undoubtedly large because of the great vol
ume of cracked gasoline manufactured daily.
The regular practice is to discard the spent
caustic. Refinery records indicate a caustic consumption of 0.2 to about 1.0 lb. per sulphur compounds to hydrogen sulphide (subsequently removed without difficulty) and to remove gum-forming diolefins. Clay
SWEETENING
Doctor sweetening of gasoline to convert smelly mercaptans into less objectionable disulphides is another old treating process that is still in much use. The gasoline is agitated with a solution of sodium plumbite formed by dissolving litharge in caustic solution. This process accounts for the heavy demand for litharge in the refining industry, although the doctor solution can be regenerated by air blowing. Refiners have reported litharge consumption from 0.1 to 0.5 lb. per bbl. of gasoline treated.
Other well knbwn chemicals used for the removal of sulphur compounds or for chang
ing them into tolerable forms are caustic in water solution, caustic solution containing various other agents such as methanol, po
tassium isobutyrate and certain organic salts, caustic-tannin solutions, sodium hypochlor to petroleum products special performance characteristics, an increasingly large amount of chemicals is used annually. Additives
Reaction tubes o f the Shell Oil Co.’s 800 bbl. per day polymerization unit which uses phosphoric acid catalyst
Hon of gums through oxidation are replac substituted catechols, cresols, benzol- and butyl-amino-phenols, phenylenediamines and some wood tar and coal tar fractions. Addi
tives have come into competition with sul
phuric acid because of the frequently high polymer and solution losses encountered in acid treatment of certain types of gasoline.
ETHYL FLUID
pensated by heavy military requirements.
Ethyl fluid is used in motor gasolines in quantities ranging all the* way from none at all to 3.0 c.c. per gal., the amount depending on the initial octane number and character
move sulphur compounds, coloring matter and, in some instances, aromatics. Agitation with sulphuric acid followed by water wash is used in neutralization. Doctor sweetening may also be' applied to kerosene and range oils. As in the case of sweetening gasolines by this method, a small amount of elemental sulphur is added to precipitate the lead as lead sulphide. Agitation of distillates with liquid sulphur dioxide is often employed for the extraction of excessive percentages of aromatics and for removal of sulphur. The liquid sulphur dioxide, which by extraction o f ' the aromatics, materially improves per
formance. Additives may be employed for the same purpose. Alkyl nitrites and ni
trates have been used for this purpose.
Lubricating oils, like gasoline, ordinarily receive chemical treatment or are subjected to treatment with chemical solvents. Petro
leum fractions containing lubricants are vari
able mixtures of paraffin, naphthenic, aro
matic and asphaltic hydrocarbons as well as derivatives and related materials. Separation of the hydrocarbons is performed by one means or another in order to produce a finished lubricant having a composition suited to a particular service. Treatment with sulphuric acid and contacting with clay have long been practiced and continued to be used to improve color, odor and stabil-
’ ity. About 15 years ago the use of solvent extraction for manufacturing preferred lu
bricants, and the addition of chemicals to lubricants to impart special qualities, began to spread. Solvents which have been used either alone or in combination include ace
tone, benzol, crcsylic acid, sulphur dioxide, ethylene dichloride, dichloroethyl ether, fur
fural. nitrobenzene, phenol and propane.
Losses of solvents are small and are confinen to physical losses from equipment and slight solution in the oils being processed. Prior to the war the total solvent refining capacity in this country was about 72,000 bbl. per day. Construction of new facilities includ
ing solvent dewaxing, benzol, acetone and methyl ethyl ketone extraction, during the war has raised this figure to approximately 94,000 bbl., an increase of 32 percent.
Of increasing importance is the use of chemicals added in small percentages to lu
bricants to improve tbeir quality. Improve
ments relate to maintenance of viscosity
ments relate to maintenance of viscosity