HAROLD CERSHINOWITZ
T. W .
EVANS
D A V I D 6. T O D D
PETROCHEMICAL PROGRESS remarkable amount of original chemical reA truly search has made pwible the profitable production
A change of emphasis in pobolefi use?
of many basic chemicals from petroleum sources. It is true that the raw materials orthe chemical industry have less glamor than its end products. The methods of synthesis in the final stages, too, are often more unconventional than those used for nreoarine feedstocks. But in many cases, the term, raw materials, is an undeserved indignity. Chemical sophistication does not necessarily make a process unrealistic, nor does need for removing trace impurities. The industry expects to produce even more exotic intermediates &om petroleum feedstocks when the demand for them develops. We define the PETROCHEMICAL INDUSTRY as that segment of the CHEMICAL INDUSTRY which utilizes feedstocks from the PETROLEUM INDUSTRY. We would like to stress
New processes, new uses for acetylene?
I
.
-
Typical of the growth of the industry is the consumption of elastomers in the United States. In the past two decades, the entire use pattern has shifted from virtually exclusively natural to predominantly synthetic rubbers. Right now, severa1 new synthetics are just emerging into commercial importance-Le., poiyisoprene iIRJ, polybutadiene IBRI, ethylene-propylene IEPRI, and ethylene-butylene IEBRI C O F O ~ ~ mers. N o doubt the seeds of other synthetic rubber trees are already germinating in laboratories a11 over the world. As these are brought to fruition, the petroleum industry can be expected to supply the bulk of the new monomers and their progenitors.
Consumption of Rubber for 1961 in US.
1961 Cupcity
An organometallic route to isoprene? Pivalic acid e a y to come iy?
A rumored new process fir phenol?
the appearance of new processes and enlarged offtakes and uses. We would also like to indicate work which so far has had limited commercialization, but either is particularly interesting scientifically, or holds promise of industrial use. Because of their spectacular growth and promising future, the monomws for synthetic rubbers are petrochemicals which deserve particular attention now. One of the developments most important to the industry is the use of organometallic compounds. Their most important application is as polymerization catalysts, but they are also beginning to be seen as intermediates in syntheses. A discussion of the industry must pay due attention to these hybrids. The most important materials supplied to the chemical industry may be grouped as:
-Ethylene and propylene -Acetylene -C, hydrocarbons including butadiene -C, hydrocarbons including isoprene -Aromatic hydrocarbons and dniuatiucs -Ammonia -Other petrochemical products, including ethylene and propylene oxides, alcohols, acids, acetaldehyde acrolein, and hydrogen peroxide VOL 54
NO. 4
APRIL 1962
23
ORGANOMETALLIC CATALYSTS Few developments have had such an impact on an industry as has the use of organometallic compounds as polymerization catalysts. This work has opened up whole new fields of chemistry, and has provided the world with extremely valuable new products. When one examines the chemistry of these reactions, it is very difficult not to be amazed at the wide variety of products that can be obtained with relatively small changes in the experimental conditions. The tables here gather together a number of examples to illustrate the tyw of work that has been done, and to give a small measure of many other possibilities. Considering the vast quantity of material already known, one is somewhat amazed not at how much of this work is being commercialized, but at how much is still left which appears promising for future commercialization. In Mono-olatln Polymers the most important reactions at present are the polymerization and copolymerization of ethylene, propylene, and 1-butene. At the moment, plant expansion is centered on the rapid commercialization of isotactic polypropylene. In its first five-year span this product will grow to perhaps 300 to 500 million pounds per year. Its attractive properties of high softening point and tensile strength are well known. Its deficiencies include brittleness at about 0' C., opacity in thick sections, and some difficulty in ultraviolet resistance. It appears inevitable that new varieties of this product will overcome these deficiencies and extend its use in many new fields. For future commercialization, an interesting use of ethylene as the sole monomer for the ethylenebutene-1 copolymer is disclosed in a recent patent (72A). A dimerization catalyst [Ti(OR), plus AIRs] is used jointly with a polymerization catalyst (Ticla plus AIRs). The competing dimerization reaction produces butene-1 which then copolymerizes with excess ethylene to give elastomeric materials.
In Diene Polymerization the outstanding successes have been the stereospecific polymerization of isoprene and butadiene to give high molecular weight polymen of controlled stereoregularity. Polyisoprene running better than 90% cis content is already being manufactured on a large scale ( 5 4 , and polybutadiene manufacture of similar high cis content is also established (704. In the case of polyisoprene part of the justification has been an economic one. Natural rubber is a commodity used on a large scale, and natural rubber production appean inadequate to meet the rising demand. In addition, however, the synthetic exhibits superior color, purity, and uniformity so that it is preferred for certain special uses. Polyhutadiene, of coune, is a different material, and as expected, it has shown both advantages and disadvantages. On the plus side, superior abrasion resistance in tread stocks, somewhat lower hysteresis, and better low temperature properties have been demonstrated. Processing difficulties have been encountered hut have been largely overcome.
OLEFIN POLYMERIZATION WITH ORGANOMETALLIC CATALYSTS-
Olefin CHFCHI CHrCH=CHz
CH-CH=CHI
CHz=CHs and CH8-CH=CHs
Ziegler Catalyst T i U , or TiClr TiClr TiCL Ti(0Bu)Gi ar-TiClt (violet) 8-TiClr (brown)
24
ZA,3A.
k Numkra are
80-90 40-50 10 80-90 40-50
Tic4 TiCI,
85
TiClr TiCI,
65 46
TiCI,
Tmdmcy to block
vu, or VCl,
Tcndmey to random copolymer
VOCla or V q O R ) , D
I
7% isotactic.
INDUSTRIAL A N D ENGINEERING CHEMISTRY
48
copolym-
DIOLEFIN POLYMERIZATION WITH ORGANOMETALLIC CATALYST9 Pmlominant Polper Pmd"C1 Ziegler Catalyst
I
TiCI, or TiCIr Ti14 TiF, TiQ.
Cydic
''% 3'4-
vmcr formed
TiQi Ti(OR), or Ti a c e t v b ionate V or MoOt+aacetylacaonatc Cr acetylacetonatc Ti(ORh or Ti a e e t v b
+
ionate
VCI, or VCII VCI, 01 V a l TiQ, Ti14
TiI,
f' f'
+'
AND FOR THE FUTURE Watch for o change of emphasis. Polyethylene and polypropylene are relatively hard, rigid plastics. Copolymers of the two ore rubbers with great promise IlA, 6A, 7AI. The potential: They are quite inexpensive and have excellent oxidation resistance. The problem: They ore very difficultto vulcanize. It is difficult to incorporate unsaturation into the molecule, ond equally difficultto develop an acceptable vulconizotion formula without it. Material with this feoture hos'been reported as nearing commercial development, however 14Al. Recipes generally call for a peroxide-sulfur cure, but with most of the peroxides tried, the systems develop very unpleasant odors. Undoubtedly this problem will be solved, but a low-cost solution is not obvious today. SUGGESTED READING (1A) Ambag, L. O., Robinson,A. E., IND. b o . CWU.53,368-70 (1961). Polymers," in Encyclopedia of Chmr (2A) Gaylord, N. G., %-gular i d Technology (R. E. Kirk,D. F. Othmcr, Anthony Standen, editor.), 2nd Supp., pp. 763-65, esp. 76373, Inmadmce, New York, 1960. (3A) Gaylord, N. G., Mark, H. F., "Lincar and Smeaspsific Addition Polymers," Inmricnce, New Yo&, 1959. (4A) Grrrham, W. F., Hunt, M. (to E. I. du Pont de Nemours & Co.), U. S. Patent 2933,480 (April 19, 1960). (5A) Hannrgsn, F. W., fibber d ) Phticr A#, 42, 16673 (1961). ).'l 87,459-65 (1960). (6A) Natta, G., B q i , 0..f i b b a r A## (N. (7A) Natta, G.,h p i , G., Di Guilio, E.,Ballini, G., Bruaone, M.,Rubbar B) PhdiwAgr42, 53-8 (1961). (SA) Natta,G., Pod, L., Zanini, G., Fiore, L., C&. e id. (Milon) 41, 52633 (1959). (SA) Natta, C., Porri, L., Zanini, G., Palvarini, A., Ibid., 41, 11639
T H Y L E N E AND PROPYL, Ethy.ae production can be called the key to the e.... petrochemicals industry. Demand of 5.5 billion pounds per year is second only to synthetic ammonia production. The ever-growing demand has led to high severity thermal crackers, hut the basic technology has remained relatively unchanged. Techniques of cracking, purification, and separation along with descriptions of commercial ethylene manufacture are comprehensively reviewed in a recent article (ZB). Process technology is being continually improved. Worthy of note are two new methods for removing acetylenic impurities. This may be accomplished by use of selective solvents (38) or by selective hydrogenation over supported palladium-containing catalysts (IB). A relatively new source of ethylene bears watchingproduction hy partial oxidation processing in cnnjunction with acetylene. Since the future installation of this type of ethylene capacity will depend on acetylene demand, these processes are discussed as methods of acetylene production, below. Propylene demand, growing too, has reached 2.4 billion pounds per year. In this case, however, supplies from catalytic cracking operations plus by-product material from ethylene manufacture have remained adequate. Actually, it appears that today only about 12% of refinery-produced propylene is used for chemicals. SUGGESTED READING
,."lo,
,*7>7,.
(1OA) Oil& 3. 59, No. 36, 1 7 6 8 (1961). W. I . B. (mImperidChemical Industries, Ltd.), U.S.Patent (11A) Reed, € ZMl6.2W (A".. 10. 1954). ( 1 2 h S-pa, B.; Stank, M.I.(to Union Carbide CoJ, Ibrd, 2,953,552 (September 1960).
6.
(1B) And-n, (1960).
H. C., Haley, A. J., E g W W., Im. Em. Cwau. 52, 901
(ZB) Davenport, C. € Plnol. I.,&$m 39, No. 3, 125 (1960). (3B) %hut& H. C., C h . E q . Prop. 56, No. 1, 53 (1960). (Caumurd mrl p n ~ e l
VOL 54
NO. 4 A P R I L 1 9 6 2
25
ACETYLENE Although acetylene is relatively new as a p e h chemical, the partial combustion of hydrocarbons provides roughly one fourth of the acetylene produced in this country. I t is, indeed, rather remarkable that over 20 years elapsed between the original demonstration of the chemistry involved and its hal utilization. The field is far from static now, however. In various stages of development are the following:
though a number of the uses for acetylene have grown enormously. A few of the particularly interesting reactions are listed in the table (74'3. The reactions leading to acrylates have now come into full scale acceptance, and are particularly important at present. SUGGESTED READING (IC)Baeearedda, M.,Neneetti, C., W a f dPilrof. Congr.,Prm., 5lh Cmm.. New York, S s t . IV, Papa 7, 1959. ( 2 0 B a q , M. J., Fox, J. M., Grover, S. S.,Brawnier, F., L a o w , P., Chm. Eng. Prom. 56, No. I, 39 (1960). ( 3 0 BlrtholomC, E., Norm-cha, H., Wafd Pihaf. C q . # Rm., 51h C w . , New York, Sect. IV,P a p 8,1959.
Plasma Jet and Eleckic Arc Techniques. It may well be that acetylene will be the first commercial product of plasmo jet research IlOc, 12cl. Showing thistrend, Du Pont has announced that its new plant ot Montague, Mich., will use a modified electric arc process, for which details are not yet available.
Modified Methane Partial Oxidation Process. Pressure operation results in greater heat recovery, increased burner capacity, reduced compressor costs, and easier removal of by-product soot ond acetylene polymers iSC, 8 0 . Production in Conjunction with Ethylene. A series of popers presented at the Fifth World Petroleum Congress showed the world-wide interest in partial oxidation processes giving both of these materials Ilc, 4c, 90. Available literature includes effects of feedstock on product distribution (Pc,1 3 0 , economics of production (6C,110,anddescriptive flowsheets 170.
3c,
I t is perhaps surprising that out of the wealth of acetylene chemistry so few things have been commercialized, al-
Pctrochnnical acetylana--for q I i c windows
ACETYLENE CHEMISTRY Raw Mntm'oi CHECH
Rmrkr Cyclopolymerization
m e (COT)
Ni(CO)., EtOH
C H d H
+ HCI
Mild temp. and
Ethyl acrylate
prcapure
CHeCH
NiBr,
CO
+ EtOH
150°-1800 C., 450
Ethyl acrylate
CH=CH
Ni(C0)r
CO
+ EtOH
A m . p m . -b mod-
Ethyl acrylate
Hydmquinone
p.s.i.g. pres.
a a t e temp.
Fe(CO).H*
50'40' C., under pres., with
CH,-C=CCH,
Fe(C0h
HrO Solution exposed to sunlight
HCI
HCI added to vinyl acetylene at 40' C
Cu,Clr
M 4 H
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Carbonylation. Ni(GO), expensive, and undesirable hyp d u c t formation Carbonylation. Slow, and s p s i a l operatinn tcchniauw re-
q u i
C H a H
CH+CH
26
Product cydwnatetra.
Dumquinoneimn viearhonyl complex Chloroprene Acrylonitrile
Carbonylation. 90p/, yi,eld; eommveial wth Rohm & Ham, Houston, Tex. Caibonylatian. 2030% yields
(4CI Braemier. F. F.. h w r. P. J... Gmbb. G. C.. Walk. W. W... Ibid... ' skt. IV, P& 6, i959. (5C) C h . Wed 87, No. 23, 60 (1960). (6C) Chmncq J., James, J. L., J. Iwt. Pebd. 46, No. U3, 337 (1960). (7C) (7Cj Hvdrmrbon Hyir-rbon Roc. B P&d. & & hh 4 O 0 ., No. 11.209.211.213 11,209,211,213 (1961). {SCj n:, New' 40; No.'ll, New Yak, 'Jbid.; Jbid., 40, No. 11, '210 210 (8C) H;dmcarbm Hydmcarbm Raeareh, Ihe.,
\.,".,_ l,Ol,\
(9C) Kdeler, H., Wirq R., Pcchmld, N., Wald Plaol. Cmgr., Rw. W Cay., Nm, York, Sst. IV, Paper 5, 1959. ( l o 0 Lcumcr, H. W., Stokes, C. S., IND.EN.. Cnu. 53,341 (1961). (11C) Lockwmd, D. C., Pebd. &jm 39, No. 11,223 (1960). (12C) MaynowsLi, C. W., Phillips, R. C., Phillips, I. R., Hiena, N. K., IND. E m . Cwu., F m o n l m ~ r a1, 52 (1962). ( 1 3 0 Reid, I. M., Linden, H. R., Chm. E%. Rw. 56, No. 1.47 (1960). J., Haar, H. B., Bellu, H. "hcydo(14) Wilkimm, J. M., Jr., We-. pdia of Chem. Tech.," Vol. 11, pp. 64845, Inferscience, New York, 1953.
..
Cd HYDROCARBONS
'.
%1
which in turn is regenerated with air in another fluidized bed (30). A b a e d combination quench tower is used. Effluent h m the dehydrogenation reactor is quenched, Grst with 20" API oil in a lower zone, then with water in an upper zone to remove undesirable polymers and emulsifrers formed during cracking ( 2 0 ) . A TwoSlclge Pmcurr in a Vapor Phase Ratetor. Olefins are dehydrogenated to diolefins in the lower section and the products are quenched with a paraffin in the upper section. The paraffin in turn is dehydrogenated to the olefin at the milder conditions prevailing in the upper section. The olefin so formed can be recyded to the lower section (130). A New DehydrogenationSystem. Iodine is used in the vapor phase for dehydrogenating paraffins and olefins to the corresponding diolefins (80). Conversion of butane and butenes to butadiene is aided by injection of controlled amounts of oxygen in the reactor ( 7 0 ) and rapid quenching of the reactor effluent (9D). This system is quite versatile. Orid.live DehydrogenationCatalysts. Such materials as bismuth phosphate (ID), bismuth molybdate (6D), and bismuth tungstate (IZD) have been reported to exhibit high selectivity at high conversion of ole& to diolefin. In these systems, oxygen is admitted with the olefin feed. Steam addition is not required for maintaining activity of the catalyst, and the reaction may be carried out at higher pressures and lower temperatures than with iron oxide4romia-potassia catalysts. C, HYDROCARBON VOLATILITIES RELATIVE TO 1-BUTENE AT 120 P.S.I.A.
(&uholal mixture ofsix Ch hydmcarbonsP Solvent-Free hbutanc
., .. . .
*Butane Isobutylene
..
I-ButCnc
ir-2-Butene 1,3-Buml*nc
PclrmhcmicoI bula&na--for tires b
The straight-chain G ' s , both paraffin and olefin, have found increasing use as raw material for butadiene manufacture (IOD, IID). Of the 1.9 billion pounds of butadiene produced in the U. S. in 1960, 85% ended up in SBR and an additional 3% in nitrile rubber. A newly introduced solvent, acetonitrile, greatly improves separation of the C , hydrocarbons by extractive distillation (5D). Expansion of existing butadiene facilities as well as some new construction has satisfied the demand for butadiene without the introduction of significantly new processing techniques. On the other hand, the literature does indicate continuing activity in research aimed at better methods. New variations disclosed for the dehydrogenation steps include: A Fluidized &d Process. Heat is supplied by circulation of hot alumina-chromia dehydrogenation catalyst
85 (4m 0)o % ~ st.iwm$
In Aquanu .&xtonitrilc*
1.11 0.87
1.69
1.02
1.01
1.00 0.85 0.99
0.86
1.38
1 .oo 0.63
IS mo* % total hydrocarboo.
SUGGESTED READING (1D) AmSmng, W. E., Vogq H. H., Adam, C. R. (m ShellDcvelopmmt Co.), U. S. Patent 2,991,322 (July 1961). (ZD)Bauman, G. P., Nirmaier, E. A. (to E m RewaKh and Engineering 2,906,791 (septmbrr 1959). (3D) Bauman, P., Bmich, F., &h&, G. (m Chem. Wake Ha),[bid., 2,930,822 (March 1960). (4D) Black, Cline, Shell Development Co., Emapille, Calif., private
w,
eommunicatim.
(5D) C h . E%. €4,No. 2,1464 (1957). (6D)Hearne, 0. W., Furmno, K. E. (m Shell M o p m e n t Co.), U. S. Patent 2,991,310 (July 4, 1961). (7J3 MuUneam, R. D., Raley, J. H. (m Shell Development Co.), Ibrd., 2,890,253 (June 9,1959). (8D) Raley, J. H. (to Shell Development Co.), Corn. Patent 576,172 (May
.,-,,.
,(ICOI
(9D) Raley, I. H., Mullinenux, R. D. (m Shell M o p m m t Co3, U. S. Patmt 2,901,610 (August 1959). (1OD) Reidel, J. C., OiIChsJ. 55,No. 48,87-8,90,93,95; No.49.115-19, 121-22 (1957). (11D) R o w b n , H. C., an.J . C h . 36, 1053-6 (1958). (1ZD) Voge, H. H..Marm, C. R. (mShellDdopment 003, U.S. Patent 2,991,321 (July 4, 1961). (13D) WoOq D. W., Maid. D. S., Hunt, J. C. (m E m R-rch and Engin-ng Co.), Ibid., 2,820,072 (January 1958).
V O L 5 4 NO. 4 A P R 1 1 ' 1 9 6 2
27
Cg HYDROCARBONS
have recently been issued for removing polymerization inhibitors with molecular sieves alone or in conjunction with metallic sodium treatment (77E,78E). Some of the routes to isoprene manufacture are: Pnpomlion of Isoprene from Cs Hydrocarbons. Conditions are didosed in a recent patent (SE). Pilot plant data illustrating the effect of operating variables have been described (6E).
Rocess Steps: -The CS stream is dehydrogenated over a chromiaalumina type catalyst at 1050' F. -Diolefins are recovered and the isoprene removed by fractionation -Residual diolefins are hydrogenated over a nickel sulfide catalyst, isomerized over silica-alumina, and recycled along with monwlelins
ModiJications:
Among the monomers for synthetic rubher, isoprene has aroused the most interest in recent years. Although natural rubber is essentially a polymer of isoprene, the monomer has been little used for synthetic rubber until the present commercial development of stereospecific polyisoprene. The small amounts required for butyl rubber have been met by steam cracking of naphthas. The major process routes to isoprene are via dehydrogenation of hydrocarbons with the required carbon backbone, or via the degradation of appropriate compounds with the correct carbon skeleton. The dehydrogenation process is analogous to butylene dehydrogenation and has received much attention recently. Isoamylene may be obtained by direct recovery from refinery streams, by dehydrogenationof isopentane, or by direct synthesis. A process for recovering high purity isoamylenes (7E)involves absorbing isoamylenes contained in the Cs fraction of gasoline in dilute sulfuric acid. The acidic stream is treated with hexane, heptane, or some other aliphatic hydrocarbon. The isoamylenes separate into the solvent and the acid phase is recycled to the acid absorption step. An alternate process involves recovery of the tertiary amylenes from the fat acid by vacuum distillation without dilution such that the acid may be recycled to the absorption stage without further treatment (4E). Most means for separating isoprene from its precursors are similar to those for separating butadiene from butylenes. Extractive distillation with aqueous acetcnitrile is as effective for Cs separations as it is for CI (73E). Further information on purification of isoprene by extractive distillation with dimethylformamide has appeared (77E). The operating conditions and performance of fractional distillation equipment for purification of crude isoprene have been presented (72E). Patents 28
INDUSTRIAL A N D ENGINEERING CHEMISTRY
~$ Roc& Stef~s:
,>
. .
?.-methyl-l-pent+ using a minum d i d acid-type catalyst to 2the presenci of hydrogen bromide splits off methane, converting 2-methyl-2pentene into isoprene Isoprene by a Process Which Employs a Pdns Reaction. F i World
This commercial process was revealed at the Petroleum Congress (OE,70E) Rocess Steps:
-Formaldehyde is condensed with isobutylene in an aqueous phase reaction in the presence of strong acids to give principally 4,4-dimethyldioxane-1,3 -The dioxane is catalytically decomposed in the vapor phase to give isoprene, water, and formaldehyde -The formaldehyde is recycled to the first step
Mod&ations: The first step may also he carried out in the vapor phase with an acidic surface-active day catalyst but with greater consumption of formaldehyde (74E).
AND FOR THE FUTURE Two routes for production of isoprene, now in the pilot plant stage of development, were indicated in the discuuion following the presentation at the last World Petroleum Congress 19EI. In the first, acetone and acelylene are condensed to dimethyl ethynyl carbinol, which is then dehydrated and partially hydrogenated to give isoprene. In the second, ethylene and propylene are condensed to form methylbutene, which in turn is catalytically dehydrogenated to isoprene. One known method of achieving this direct condensation is via a trialkyl oluminum intermediate (3EI. SUGGESTED READING
(le) Anhorn, V. J., Frsh, K. I., Brown, D , SehaKd, 0. S.,C h . Eng. Prop. 57, No. 5, 43 (1960. (2E) C h Week 87, No. 18, 39 (1960). (3E) Continental Oil Co.,Houston, Tex., Brit. Patent 837,088 (June 1960). (4E) Cmuq B. F., WhitnLcr, A. C. (to Gulf Rcsarch nod Dnrdopment Co.),U. S. Patent 2,968,682 (January 1961). (5E) Dcmpoey, J. F. (to Sun Oil Co.),U. S. Patent 2,914,588 (Nwcmba 1959). (6E) Digiwmo, A. A,, Maerker, 1. B., S h a l l , 1. W., C h . Eric. Prop. 57, No. 5,35 (1961). OE) FOaa, R. L., Wunderlih, D. K., Patidin, S. H., Sanford, R. A., Plbol. Rejw 39, No. 11,229-32 (1960). (8E) Hdncmann, H.,MilliLen, T. H., S t w n , D. H. (to Houdry b e a s Cop.),U. S. Patent 2,900,429 (Aupit 1959). (9E) Hellin, M.,Guerpillan, H., Cowsemant, F., Parrol. Ew. 31, No. 12, r-li - - (1959) ,----,(1OE) Hellin, M. C. F., Coursemant, F. C. (to Inn. Francair du P m l c ) , U. S.Patent 2,962,507 ( N o w m k 1960). (1lE) Henke, A. M.,StluKer, H. C. (ta Gulf Research and Development Co.),I6id.. 1,900,430 (August 1959). (1ZE) Lynn,R. E., Healy, J. C., C h . Et& Prop. 57, No. 5,46 (1961). (13E) MR. C., Evans,T. W. (to Shdl Development Co.), U. S.Patent 2,431,230 (March 2, 1948). (14E) Oldham, W. J. (British Hydrocarbon Chcmicsla, Ltd.), Brit. Patent 826,545 (January 1960). (15E) Rcilly, P. M.,Lewis, E. P., Kearna, W. J. L. (to Polymer Corp.), U. S. Patent 2,884,473 (April 1959). (16E) Shdl Inmnatiorml Research Maatuhappij, N. V., Australian Patent Appl. 5772540 (1960). (17E) Swamon, R. W.,Gent=, J. A , J . Chm. Eng. Dofa 7,132 ~
(1962). USE) Wolfe, J. S. 9. (to Gmdrieh Gulf), U. S. Patent 2,935,540 (May 1960).
AROMATIC HYDROCARBONS AND DERIVATIVES The picture of aromatic production is now underping a complete change. Benzene has been in very short supply an several occasions. This has resulted in occasional large imports, greatly increased benzene recovery capacity, and investigations into the use of toluene in the place of benzene. The various dealkylation methods available have recently been reviewed (7F). Attempts to use toluene have so far resulted in two types of commercial processes : f -DmathMtion of tdum to gim bmzm rlsdf -Manufacture of p h l from toluene instcod of bmme Future relative prices, on a molecular basis, of benzene and toluene cannot be predicted with assurance. It is apparent, however, that certain people feel the price difference will remain large enough to justify thii kind of work, because planned capacity for benzene from toluene
is about 170 million gallons per year. The chemiswy involved in the phenol synthesis is interesting (7F). w e b s t step consists of the oxidation of toluene by air in th6 presence of a cobalt catalyst to give benzoic acid. The benzoic acid is converted to phenol in a second step, either hy reaction with oxygen using a solublu copper catalyst and steam (SF). or by reaction withfibxygen ushg copper oxide catalyst, giving phenyl benzoate, which is then hydrolyzed to give phenol (IgF); or by reaction with copper oxide (separately regenerated) diL. rectly to phenol (3F). Phenol capacity has been considerably expanded, but no one process dominates the phenol i n d p y . ‘he”c1assical process of sulfonation followed 6y caustic hsion is still used. In fact, some recently added capazity has been of this kind. A large amount of phenol is produced by direct chlorination of benzene to chlorobenzene followed by caustic hydrolysis, and there has also been some recent expansion by this method. The Raschig modification of this process ha5 also been under&ing expansion. This inyolves catalytic hydrolysis of chlorobenzene to give phenol plus HCI, followed by generation of chlorobenzene through the reaction (again catalytic) of benzene, HCI, and air. A good deal of recent capacity has come through the cumene route which produces acetone as a co-product. The extra value of the acetone is extremely important in setting the economics of the process. The projected commercialization of the route through mluene has already been mentioned. Birphenol A is an important derivative of phenol. It is a basic raw material, when combined with epichlorohydrin, for epoxy resins (SF,9F). The U S. market for the unmodified Biphenol A based resins now runs in excess of 50 million pounds per year. Caprolactam synthesized from toluene by way of benzoic acid is another interesting process which broadens the supply of aromatic raw materials. In this case, the benzoic acid is hydrogenated to the hexahydro derivative, and then allowed to react with nitrosyl sulfuric acid Naphthaleneproduced from petroleum products-by dealkylation of alkyl naphthalenrsis also planned (7F) The case here seems to be somewhat different from benzene, in that there is no large amount of naphthalene itself in any of the petroleum streams. Nor are hydrogenated naphthalenes available for synthesis in the way that methyl cyclopentane and cyclohexane have been available for benzene synthesis. Historically the source of naphthalene has been coal tar. The increased demand for naphthalene plus fluctuations in the steel industry, which are of course reflected in coke production, finally made alternative sources of naphthalene economically feasible. Styrene has a major outlet as polystyrene, and is second only to butadiene in total quantity appearing in synthetic rubber. Substantially all of the commercial styrene is produced by dehydrogenationof ethylbenzene. While ethylbenzene is made predominantly from ethylene and benzene in the presence of a Friedel-Crafts type catalyst, at least one unit has been put on stream for the direct recovery of this hydrocarbon by fractionation from V O L 5 4 NO. A
APRIL 1962
29
AND FOR THE FUTURE
Phenol is an unusual exomple of the versatility of the chemist and engineer in devising o number of competitive processes. In addition to those listed here, others may yet be added. There is olwoys a possibility of o synthesis from cyclohexane by way of direct oxidation of cyclohexanone. There are recurrent rumors of a process for the direct oxidation of benzene to phenol. SUGGESTED READING UP) Agndlo, L. A., William, W. H., Im. EN. I4 om\ ,-~"-,. (2p) And-,
CHBM.52, 89C900
E. V., Bmwn, R., Bdton, C. E., Ibid., 52, 550 (1960).
OF) Barnard, R. D.,Mqer, R . € (to I. Dow Chemical Co.),U.S. Patent 1,852,567 ( S o t . 16. 1958). (4* C&. W& 85, No. 6,'39-44 (1959).
(5F) E u W H. W.,Lwis T., Schiller,J. C., Ckm. &. News 89, No.37, 128 (Sent. 1961). . ~ 11. ~~, ~ ~~ I .~ ~ , .~ ~~~
(6F) Harvard University, Graduate S c h d of Buainesl Administration, Material Research, Cambridge, Mas., "Epov Reins, Market Survey and Urn' Relameq" 1959. (7F) Iwo. ENO.Cmu.54, No. 2 2 9 (February 1962). (SF) Kacding, W. W., Lindblom, R. 0. (to Dow C h d c a l Co.),U. S. Patent 2,727926 (De. 20, 1955); rriarved No. 24,848 (July 25 ,1960). (9F) Lee, H., Neville, K., "Ep0.y Reins, Thdr Application and Technol4ly.'. McGraw Hill, New York, 1957. (10F) Ogata, Y., Tsuehida, M., Muramom, A., J . Am. Ckm. Sm. 79, 6005-8 (1957). (11F) Shawood, P. W., Ckm. h) Z d . 55, 10961100 (1960). (12p) Toland, W.G., Jr. (to California R-b Corp.), U. S,'Patat 2,762,838 (Sept. 11, 1956).
a C, aromatics cut (ZF). This appean to involve essentially a willingness to utilize something l i e 200 trays plus the requisite reflux for the separation. At the moment some additional capacity is under consideration for this route. Other Aromatic Derivatives are also undergoing change.
-0-Phthalic anhydride production by oxidation of naphthalene remains the preferred process. Some capacity from o-xylene is in operation, however. -1rophthalic acid by large-scale oxidation of m-xylene has been undertaken. Extensive work has been done on utilization in surface coatings and fibers. -Tcrcphthnlic acid production from #-xylene continues. The p-xylene is recovered by crystallization from a selected xylene fraction. There is some evidence that a competitive synthesis from benzoic acid in the presence of carbon dioxide may be possible (77F). If so, this is another example of a valuable reversal of a previously well known reaction-namely, the decarboxylation of terephthalic acid itself. However, the reaction goes even in the absence of carbon dioxide (IOF). -Qrorncllitic dianhydride has aroused sufficient interest to make several companies look at the possibility of securing durene (1,2,4,5-tetramethylbene) from petroleum. By means of its high melting point (80' C.), durme has been isolated in large quantities from selected fractions. In addition purely synthetic methods have been evolved for its manufacmre (4F). Commercial quantities of durene are now available, as well as other polymethylbenzenes (SF). Reports in the trade that production of pyromellitic dianhydride has been discontinued are incorrect. It is available in limited quantities at 85.00 per pound from D u Pont. SO
INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
AMMONIA Ammonia production is an industry of spectacular growth, but little innovation. In manufacturing, the principal technical innovations in this industry are: Some refinery by-product hydrogen from catalytic reforming processes has found its way into ammonia synthesis
Significant improvements have been made in the manufacture o f synthesis gas, particularly in the partial combustion processes New urea capacity has been added.
But g o d , competitive ammonia plants can be purchased off the shelf. In consequence, this i s a highly competitive, law profit-margin industry which i s so well developed that future outstanding technical developments are likely to be few and far between. Instead the energy o f the technical people is probably directed to problems such as local plant efficiency and bottleneck removal, to achieve maximum return.
OTHER PRODUCTS Ethylene and Propylene Oxides Ethylene oxide production in the U. S. has grown enormously, reaching roughly 1.5 billion pounds per year. This growth has been almost entirely through the direct oxidation route. Propylene oxide has p w n also, but in t h i s case through chlorohydrhation. M u c h of this has been in plants previously used for ethylene. T h e former markets for both of these oxides have continued to grow. In addition, a large new offtake h a s been introduced with the requirements of poly (propylene oxide) for polyurethanes. By virtue of low cost and satisfactory performance, thii material i s dominating the field. In excess o f 80 million pounds per year of polyethers i s currently used in polyurethanes.
alcohol manufacture by h t making aluminum alkyls an$ *then oxidizing these alkyls to alcohols (ZC) In the meantime, the Oxo alcohols themselves have grown to about 600 million pounds per year.
AND FOR THE FUTURE One of the more intriguing of the newer potential processes is the synthesis of acids from olefins and carbon monoxide in the presence of an acid catalyst such as sulfuric acid. The
synthesis i s simple and straightforward. The reaction proceeds with both olefins and alcohols, working best with the tertiary structures and next with the secondaries. Curiously, the literature indicated many years ago that certain acids in the presence of sulfuric acid decomposed to give olefins and carbon monoxide 13Gl. and of course the decomposition of formic acid by sulfuric acid to give carbon monoxide and water has been a standard laboratory route to carbon monoxide far a very long time. It has also been common knowledge that alkali with carbon monoxide gives formates, while alcohols with C O give formic esters. The realization of the wide scope of this reaction and its simplicity, however, appears to be rather recent and at least a few of these materials should be commercialized. The reaction proceeds with ease in the case of isobutylene. which could makepivalic acid available as a commercial chemical 19GI. In many ways this i s quite remarkable, for pivalic acid has never been easy to come by. Chemically a rather interesting variant is found when a material such as 2-methyl-24-dihydroxypentane i s subiected to this reaction. In this case a carbonyl group is introduced at the site of the tertiary hydroxyl which forms an ester with the other hydroxyl, leading to a lactone IsGI.
AND FOR THE FUTURE
CH,-C"-Ch P P I h
The direct oxidation route to ethylene oxide is a very important process. Much work has been done on it. But it i s surprising that there is still only one catalyst that worksmetallic silver. Equally surprising, there is no known catalyst for a parallel process making propylene oxide. Here, a direct noncatalytic route i s possible, but so far, such a process i s not attractive if propylene oxide i s the sole desired product.
coon i
f
O(,-CH--wI llabqrir Add
IC-c-c-L N-l
Acids and Alcohols T h e Oxo process continues to increase in importance. A certain amount o f product from this reaction does end up as acid, but by far the largest part emerges as alcohols. At the present time propylene and some of its lower polymers and copolymers are the most important of the feedstocks. T h e higher alcohols, in the Ca range, enter into plasticizer manufacture where they compete with 2-ethylhexanol made from acetaldehyde and butyraldehyde. Recent plant additions suggest that the Oxo route is the preferred one, but it i s always possible that newer processes may alter the situation drastically. Thus, a plant i s presently under construction for higher
+ co + H,o
1
I
c-c-c:I,,
.
AUTHORS Harold CnEhinowitz is the Residmt of Shell De-
w.
velopnmt Company, New York, N . Y . T . Evans is tlu Vice-Resadent and h a 1 Managn of Shell Development Go.. Emeryville, Calif. David B. Todd is a Supcrvuor in the Syn. thtic Rubbn Project Development Department of Shell Develop. mmt Co., Emeryuille, calif. V O L 5 4 NO. 4
APUII 1962
31
Acetaldehyde Production
AND FOR THE FUTURE
A most interesting application and extension of some older chemistry has occurred in the manufacture of acetaldehyde. The primary reaction is one of palladous chloride with ethylene and water to give the aldehyde. The palladium compound acts as a direct oxidant and is reduced to the metal. Subsequently this palladium metal is oxidized to regenerate palladous chloride. One of the factors making for success was the discovery that copper ions catalyze oxidation of the palladium. The process can be carried out as either a single-stage or two-stage operation. In the single-stage version, oxygen and ethylene are admitted simultaneously to the reactor so that oxidation and regeneration occur in the same vessel. In the two-stage operation, which can use air instead of oxygen, the ethylene is oxidized in one vessel, the palladous chloride regenerated in the other. The process is in operation in Germany and (as recently announced by Celanese) is scheduled for introduction to the United States in the near future. It is again most interesting that in a situation involving such simple chemistry, which is so important that it has been studied extensively for many years, a competitive variant based largely on known chemistry can still arise.
Acrolein derivatives can be expected to follow availability of the raw material. Some of the most likely compounds will be glutaraldehyde, o-hydroxyadipaldehyde, and 1,2,6-hexanetriol.
Acrolein Production
The catalytic oxidation of propylene to acrolein has recently been introduced commercially (7G, 74G). This is a reaction which has been fairly well studied in past years. In particular much work has been done on derivatives which can be made economically from acrolein (?G,73G, 75G). In the case of a recently constructed plant, a large glycerol unit using acrolein and hydrogen peroxide as raw materials is tied into the venture. However, with industrial production now under way, it is likely that a number of acrolein derivatives will appear. Some very interesting work has also emerged on new catalysts for the vapor phase oxidation of propylene to acrolein, particularly catalysts containing bismuth phosphomolybdate (4G). These have allowed both high conversion and high yield per pass. In addition, with these catalysts, when ammonia is included in the feed, the reaction goes smoothly to acrylonitrile. One commercial plant in the United States has recently started operation of this process and there are some indications that plants niay be built abroad (16G). In the meantime additional capacity for acrylonitrile has been built in recent years using the HCN-acetylene route. Improvements in the process included passing the gases into an acidic nonaqueous catalyst solution of cuprous chloride dissolved in an organic nitrile (6G),or passing the reactants in the vapor phase over charcoal impregnated with NaOH ( 7 IG). Recent process improvements disclosed for the purification of crude acrylonitrile involve a refining step which avoids contamination of the refined acrylonitrile with HCN (8G), and use of a separate water extraction before final stripping (TOG). Demand for acrylonitrile has grown steadily and earlier predictions of its becoming a major industrial chemical have been verified. 32
INDUSTRIAL AND ENGINEERING CHEMISTRY
Hydrogen Peroxide Manufacture and Use
Somewhat earlier the use of hydrogen peroxide in a new glycerol synthesis was mentioned. Much work has been done in recent years aimed at challenging the electrochemical preparation of hydrogen peroxide. A number of possibilities have been explored, including new approaches using the higher oxides of some of the metals, selective oxidation of hydrocarbons to give hydrogen peroxide among other products, and finally selective oxidation of organic compounds other than hydrocarbons. Only two of these processes have reached commercialization, but they are proving very important. In one process, an alkylated anthrahydroquinone-quinone cycle is used. In the other a secondary alcohol is oxidized to a ketone with the simultaneous production of hydrogen peroxide (7G, 72G). The last process is of course of direct interest to the petrochemical industry. Judging by recent construction, it appears that the organic processes are more attractive than the electrochemical one, and it appears likely that any additional capacity will be based on some such process. While a great deal of exploratory work has been done on the chemical utilization of hydrogen peroxide, at the moment the only large new commercial uses appear to be in glycerol and epoxide syntheses. In the meantime, it may be noted that competition in glycerol manufacture is appearing from a completely new source, the hydrogenation of carbohydrates. In a way, the successful utilization of ozone as an oxidant may offer competition in reactions where otherwise hydrogen peroxide would be used. A very closely related development is the direct use of a peracetic acid solution by the direct oxidation of acetaldehyde. SUGGESTED READING (1G) Ballard, S . A., Finch, H. D., Geyer, B. P., Hearne, G: W.,Smith, C. W., Whetstone, R. R., World Petrol. Congr., Proc., 4th Congr. Rome, Section IV, 141-54 (1955). (2G) Bateman, J. W., Petrol. Refiner 40, No. 4, 147-9 (1961). (3G) Bistrzycki, A,, Mauron, L., Ber. 40, 4370-8 (1907). (4G) Callahan, J. L., Foreman, R . W., Veatch, F. (to Standard Oil Co., Ohio), U. S. Patent 2,941,007 (June 14, 1960). (5G De Benedictis, A., Furman, K . E. (to Shell Development Co.), Zbid., 2,913,489 (Nov. 17, 1959). (6G) E. I. du Pont d e Nemours Co., Wilmington, Del., Brit. Patent 824,593 (December 1959). (7G) F M C Corp., Becco Chemical Div., New York, Hydrocarbon Proc. B Petrol. Refiner 40, No. 11, 255 (1961). (8G) Hadley, D. J., Steward, D. G. (to Distillers Go., Ltd.), Brit. Patent 835,962 (May 1960). (9G) Koch, H., Brennstof-Chem. 36, 321-8 (1955). (10G) Lovett, G. H . (to Monsanto Chemical Co.), U. S. Patent 2,947,777 (August 1960). (11G) Robertson, N. C., Steadman, T. R., Gabbett, J. F. (to Escambia Chemical Corp.), Brit. Patent 812,475 (April 1959). (12G) Rust, F. F. (to She11 Development Co.), E. S. Patent 2,871,104 (Jan. 27, 1959). (13G) Shell Chemical Co., New York, N. Y., “Acrolein, Its Chemistry and Applications,” Bull. SC,59-65 (1959). (14G) Sherwood, P. W.,World Petrol. 31, S o . 12, 60, 62, 64, 121 (1960). ( l j G ) Smith, C. W., “Acrolein,” Wiley, N. Y., to be published. (16G) Veatch, F., Callahan, J. L., Idol, J. D., Jr., Milberger, E. C., Chem. Eng. Progr. 56, No. 10, 65-7 (1960).
