Commercial Syntheses of Organic Petrochemicals
are in a slow-growth phase with an annual Surfactants output of about 1.8 billion pounds. Two major shifts within the industry are being felt as liquid detergents and nonionics are rapidly capturing a larger share of the market. Hardest hit by these developments are the alkyl benzenoid sulfonates (ABS)-i.e., the group of anionic detergents which are the industry's workhorse. Biggest beneficiary of the shift are alkanolamides, alkyl phenolethylene oxide adducts, tall oil-ethylene oxide adducts, and fatty alcohol-ethylene oxide adducts. T h e unfavorable market outlook for ABS is further aggravated by a widespread concern that its residues may be responsible for difficulty in sewage plants due to low biodegradability and high foaming rates. Efforts to overcome these difficulties include use of cracked wax olefins of largely straight-chain structure or synthetic straight-chain olefins in lieu of more highly branched propylene tetramer as alkyl side chain; use of sulfated straight-chain alcohols in lieu of ABS; and development of improved methods for sewage treatment. Among automotive chemicals, antiknock compounds such as T E L and T M L are the biggest factor. The petrochemical industry's part in this field is the production of the key intermediates ethyl chloride and methyl chloride, as well as of the scavengers, ethylene dichloride and ethylene dibromide. Also, in this article, ethylene glycol is included among automotive chemicals. I n agricultural Chemicals, the big entries are ammonia, an inorganic chemical, and marginally organic urea. Both are considered outside the scope of this report. Nor have we included the fairly large group of fungicides, herbicides, insecticides, plant hormones, soil conditioners, and fumigants, This is a customer industry for numerous organic intermediates covered elsewhere in this report. T h e following processes play a key role in the production of organic petrochemicals which find their primary markets in the fields of surfactants, automotive applications, and agricultural chemicals.
RAW MATERIALS FOR S U R F A C T A N T S AND AUTOMOTIVE CH EM IC A L S PETER W.
SHERWOOD
121. Isothermal operation in shell-and-tube unit. Typical conditions: 900 p s i . ; 95' to 100' C.; 92% olefin conversion. This process does not require catalyst regeneration, and is the basis of most modern Dlants.
PROCESS
Feedstock is dilute (30 to 507,) propylene; it must be free of sulfur, N compounds, oxygen, butadiene, and excess water. Low-boiling product is recycled. Tetramer yield of about 757, can be attained. Dodecy,benzene
This has largely supplanted keryl benzene. The latter can be produced from paraffinic petroleum stocks in the C ~range, Z which are first chlorinated and then allowed to react with benzene in the presence of A1C13.
+
C12H24
(generally propylene tetramer)
-c
RAW M A T E R I A L S FOR SURFACTANTS t
-+
1Z H25
Propylene Trimer and Tetramer (Nonene and Dodecene)
nC3He
-+
(C3He)n where n = 3 or 4
For polymerization of propylene to its trimer and tetramer, phosphoric acid-based processes predominate. Typical is the use of phosphoric acid on kieselguhr carrier. Three types of reaction systems are employed. PROCESS 119. Adiabatic catalyst-packed tower operated slightly below stabilizer pressure (>250 p s i . ) of the olefin source. Temperature is 95' to 140' C. I n this scheme, catalyst fouling is rapid ; frequent regeneration is needed.
120. Adiabatic operation of catalyst-packed tower at 500 p.s.i. minimum. Allows lower temperature (90' to 110' C.) ; cuts down on catalyst fouling, and raises conversion. PROCESS
PROCESS 122. AlC13 catalyst. Liquid phase. Typical conditions: 45' to 55' C.; benzene to tetramer mole ratio, 7.5; catalyst content, 1% (on total charge); 70% yield on tetramer.
123. Anhydrous HF catalyst. Liquid phase; 0' to 10' C. Mole ratio of benzene to dodecene, 8 to 10. HF to dodecene, 4 : l . Yield, 78 to 80% on tetramer. PROCESS
Other process. 96.5 to 1 0 0 ~ oH&04 catalyst; 0' to 10' C. Process believed no longer practiced because of excessive side reactions (oxidation and sulfonation) causing loss of yield, high acid consumption, lowerquality product. (Continued on next page) VOL. 5 5
NO
4
APRIL
1963
33
Ethanolamines PROCESS
124. CHz-CHz
\ /
+
Straight-Chain Primary Alcohols 3"
>-
PROCESS
3ROH
0
HO-CH2-CHz-NH 2 monoethanolamine This is an equilibrium reaction. Ammonia is used in considerable excess to minimize formation of ethylated alcoholamines higher than the main desired product. Formation of oxyalkyl ethers can be suppressed by addition of C O Z . This is especially significant in production of triethanolamine (TEA). Typical operation: liquid phase; 25 to 307, aqueous ammonia; 35'to 40' C . ; 1- to I1/2-hour reaction time. For MEA production, typical ammonia to ethylene oxide weight ratio is 3.6: 1 to yield 507, ME.4, 307, DEA, 15% TEL4,and 5'33 residue.
127. R3Al -4lz(s04)3
+
+ I1/z
O2
--f
(R0)341
H9SOa
R3iil obtained by buildup reaction, discussed under process 125, or by introduction of long-chain olefins from other sources [Ziegler, K., Ann. 629, 246 (1960)l. Introduce air into liquid phase a t 30' C., allowing temperature to rise gradually to 95' C. Atmospheric pressure. Top off hydrocarbons in falling-film evaporator at 180' C. and 1 atm. Treat bottoms with sulfuric acid. 40' C., atm. pressure. Yield, 70 to 807,. Subsequent improvement has resulted in higher yield. Product composition ~ollows a Poisson distribution curve. For example: 70
15 18 19 18.5 15
C6
cs
For TEA production, NH3 to CzH40 weight ratio, 0.20 to 0.24. IVith COz addition, product contains 92.5% TEA and 5.5% DE,4.
C10
ClZ C14
8
Cl0
linear Alp h a-Olefins PROCESS
125. a. Build-up reaction R - A1 n(CzH4) -+ R(CzH4)sAl [ = Al(alkylJ)a] b . Displacement reaction C2H4 Al(alk>-lI)zCzHj Al(alkylr)3 olefin'
+
+
+
---f
Method of execution [according to Zosel, K., Brennstof-Ciiem., p. 321 (Nor.. 23, 1960)]: a. Buildup reaction: copper reactor; continuous operation; 160' C . ; 150 a t m . ; 675 grams ethylene conversion per hour per liter reactor space. Recycle, C12 to C14 olefin from displacement reaction. 400 qrams Al(CzHJ3 yield 1750 grams of product of average length, C1l.
noncatalytic ; 285 ' C. ; 10 atm.; 0.7 second residence time (for ethylene): feed ratio: R3Al to CzH4, 1 : 12.
6. Displacement reaction:
+
Over-all example: 100 kg. Al(C2Hi)3 ethylene 207 kg. C4-C1o 126 kg. C1z-Ci4 67 kg. Cie-C22
+
TEA loss is about 1 weight be partly recoverable).
+
7, on olefin formation
+
(may
Molecular weight of product follows Poisson distribution curve. About 95% straight-chain alpha olefins. PROCESS 126. Cracking wax from highly paraffinic crude oil. Thermal (steam) cracking. Vapor phase. 550' to 575' C. 20 to 507, conversion. Product follows Poisson distribution curve. Typical product in key ranges:
New7 process possibility, not yet commercial : telomerization of methanol and ethllcne catalyzed by peroxides, etc. Difficult to control. High cost of catal>-st still a major obstacle. Higher olefins (propylene, but) lene) will react with methanol to yield more highl) branched lonq-chain alcohols.
AUTOMOTIVE CHEMICALS Ethyl chloride (as intermediate for TEL)
CH2=CHz
+ HC1+
CH3CH2C1
128. Vapor phase. Catalyst: copper chloridepromoted zinc chloride on alumina. 175' C . ; 250 p.s.i.g.; 1 pound mixed feed per hour per 1.8 pounds catalyst. Ethylene conversion is 907, per pass. Ethyl chloride yield is 99.5y0on ethylenc converted.
PROCESS
123. Liquid phase. Catalyst: aluminum chloride in liquid complex with ethyl chloride; other possible catalysts include BFB-H3P04 and combinations of AIC13 and FeC13. Dilute ethylene is feasible feedstock. HC1 to ethylene ratio is essentially stoichiometric. Operation at HCl to ethylene feed ratio of 1.06:1, 52' C., 125 p.s.i,, with addition of 0.5 to 2 volume % acetylene (based on ethylene) is reported to result in the following consumption per 100 pounds of ethyl chloride produced: 45.4 pounds of ethylene; 62.6 pounds of HCl; 0.6 pound of AlC13. I n the absence of acetylene, consumptions are reported at 46.1, 64.9, and 1.0 pound, respectively (UsS. Patent 2,786,875). PROCESS
Peter W. Sherwood is a Chemical Engineer in White T h i s is the last in a series of six articles based, in part, on lectures gioen to an industry symposium at the University of California in M a y 1962. AUTHOR
Plains, N . Y .
34
I N D U S T R I A L A N D ENGINEERING
CHEMISTRY
Wyandotte Chemical’s plant for making probylene glycol by chlorohydrination
PROCESS 130.
C2H6
+ Cl2
--+ CH3CHzCl-l-
HC1
Vapor phase. Above 230’ C. Catalytic-e.g., activated charcoal-photochemical, or thermal. Typical thermal chlorination conditions: a, 420’ C . ; 80 p.s.i.g.; 3 seconds contact time. b, 390’ C.; 110 p.s.i.g.; in fluid-bed system using sand. Cln to C2H6 ratio determines product distribution. For example : Product Distribution, Mole yo (HC1- and C2Hr Free Basis) DichloroTrichloro: Ethyl ethanes ethanes chlorzde
-
Cl2 and C2H6 Mole Ratio
0.2 0.4 0.6 PROCESS
131.
95.5 90 84 C2H60H
0.5 3.0 5.5
4 7 10.5
+ HC1
---f
CzHsC1
+ H20
Today of minor significance for ethyl chloride production. Vapor phase over ZnC12, etc., or liquid phase in the presence of aqueous 5Oy0 ZnCl2. Reported conditions in liquid phase: 145’ C., 30 p.s.i.g., 98% yield (on ethanol).
Chlorohydrination in aqueous chlorine solution ; 20’ to 35’ C. Pressure ranges widely-high pressure favors ethylene solubility. Process feeds 20 to 50% excess ethylene which may, however, be dilute. Direct contact between ethylene and undissolved chlorine must be avoided. Product is allowed to build u p to 4 to 8% ethylene chlorohydrin content. I t is fed directly to saponification stage, b . a.
b. Saponification of chlorohydrin by 10% aqueous lime slurry. 96’ to 102O C . ; 0 to 10 p.s.i.g.; pH, 8-9. Over-all yield, 80 to 82y0. By-products, ethylene dichloride and bis(2-chloroethyl) ether. Comment: Originally the main source of ethylene oxide, the relative importance of this route has declined markedly during the 1950’s, being gradually superseded by processes 133 and 134. Advantage of process 132 is high utilization of ethylene and suitability of dilute ethylene. Disadvantages include cost of chlorine and lime, relatively high plant cost, and formation of byproduct calcium chloride in a not readily marketable form. PROCESS
Ethylene Dichloride and Ethylene Dibromide
Scavengers in lead alkyl mixes. Ethylene dichloride is discussed under “Vinyl Chloride,” and ethylenr dibromide is considered outside the scope of this discussion-in its manufacture, bromine is by far the major cost component.
133. CH*=CH*
+ air
--+
CH2-CHs
\ / 0
PROCESS
134. CH2--CH2
+ oxygen
.--f
CH2--CI-12
\ / 0
Ethylene oxide PROCESS
132.
CH2=CE-12
+ Cl;! + H2O CH2--CH2
I
OH
I
C1
lime
133 AND 134. Reaction of ethylene and molecular oxygen in vapor phase over supported metallic silver catalyst at 240’ to 290’ C. Ethylene concentration in reactor feed must be 3 to 570-i.e., below explosive limit. Admixture of less than 1 p.p.m. of ethylene
PROCESSES
-+
CHn-CH2
\ / 0
VOL.
55
NO. 4
APRIL 1963
35
dichloride to the feed is practiced to minimize complete combustion reaction. Hydrocarbons other than ethylene must be substantially absent from feed.
Comment: Process 137 appears to be practiced at only one U. S. plant which was installed during the late 1930’s or early 1940’s.
PROCESS 133. Uses air as oxidizing agent. Conversion is on a once-through basis in two reactor stages set in series. I n the first reactor relatively mild conditions aim at maximum yield of ethylene oxide-e.g., 307, conversion and 707, selectivity. Following removal of this product by water scrubbing, the residual unconverted ethylene is taken through a second reactor where it is subjected to more drastic, less selective conditionse.g., 767, conversion and 557, selectivity. Over-all yield is reported at about 657, of theory.
AGRICULTURAL A N D MISCELLANEOUS CHEMICALS
+
134. Employs 957, oxygen in lieu of air. A single reactor serves. Conditions in the reactor are relatively mild, aim at top yield. Product is scrubbed from reactor make gas; bulk of unconverted ethylene is recycled. Yield is about 67 to 6970 of theory. PROCESS
Ethylene Glycol
CHz-CHz
f HzO
-+
OH
0
Urea PROCESSES
2NH3
135 TO 140.
+ COz
+NHZCOONHA -+
NHzCONHz
At least six processes using this reaction system are in operation. Urea is considered outside the scope of this report. A brief summary of reaction conditions in the various processes is given by P. H . Groggins in “Unit Processes in Organic Synthesis,” 5th ed., p. 479, 1938, and Chemical Week, p. 68 (Nov. 12, 1960).
I
Hydrogen Peroxide
OH
By-products : diethylene and triethylene glycol. catalysis us. thermal, high-pressure hydration.
OH H2S04
135. Liquid phase. 0.5 to 1.0 weight yo H2S04 in water serves as catalyst. 50 to 70’ C.; 30 minutes contact time.
I
PROCESS
141. 2CH3-CH-CH3
+
0 2 +
0
I1
PROCESS
136. Liquid phase. No catalyst. Weight ratio H2O to ethylene oxide, 6 : 1. 195’ C. ; 200 p.s.i.g. ; 1 hour residence time.
PROCESS
Processes 135 and 136 form glycol in 88 to 937, yield. Higher glycols constitute the bulk of by-product. A developmental process involves liquid-phase hydrolysis of ethylene oxide in the presence of ion exchange resins, with yields up to 85%. PROCESS
late
H? --+
-
137. From formaldehyde and carbon mon-
oxide in three steps:
-+
glycolic acid
ROH
methyl glyco-
glycol
Production of glycolic acid. Liquid phase. HCl or H2S04 catalyst. 150’ to 225’ C . ; 500 to 1000 atm. a.
b. Production of methyl glycolate. Liquid phase; sulfuric acid as catalyst. 800 to 900 atm.; 210’ to 2200 c. c. Conversion to glycol. Vapor phase over copper oxide-zinc oxide-chromia, catalyst ; feed composition, 97% HP and 3% methyl glycolate. 210’ to 215’ C . ; 30 atm.; 9000 to 10,000 hr.+ space velocity. or
Liquid phase, using MgO-promoted copper oxide as catalyst. 400 atm. hydrogen pressure. 225’ C., 10-30 minutes contact time. 36
+ H20
CHz-CHz
I
\ /
Main petrochemical products consumed in this area are ammonia and urea. A discussion of ammonia, an inorganic material, is deemed outside the present scope. Methods for obtaining its main raw material, hydrogen, from petroleum sources have been discussed previously.
INDUSTRIAL AND ENGINEERING CHEMISTRY
2CHa-C-CH3
+ H2Oz
Liquid phase. L4utocatalytic-e.g., H202 itself is the catalyst. Typical conditions, 80 to 957, oxygen; 90’ to 140’ C . ; 200 to 300 p.s.i.g. Absence of decomposition-promoting metals (such as Ni and Fe) is essential. H202 concentration is allowed to build up to 15 to 25 weight 7 0 before withdrawal from reactor. Reported yields on isopropanol : acetone, 93% and hydrogen peroxide, 877, of theory. Alternative sources for hydrogen peroxide include mainly oxidation-reduction cycle of alkyl anthraquinones and electrolysis of ammonium bisulfate. Carbon Black
Although a major petroleum-derived product, this is not strictly speaking an organic petrochemical and is therefore not included in the present discussion. Fluorocarbons
I n these products, fluorine is by far the most expensive raw material. Fluorocarbons are therefore considered outside the proper scope of the present discussion. Reprints of this entire series-six for one dollar from:
articles-may
be obtained
REPRINT DEPARTMENT ACS Applied Publications 1155 Sixteenth St., N.W. Washington 6, D. C. Special quotations for bulk orders furnished on request.
