Ind. Eng. Chem. Prod. Res. Dev., Vol. 17, No. 3, 1978 Barrer, R. M., White, E. A. D., J . Chem. SOC.,1261 (1951). Barrer, R. M., White, E. A. D., J . Chem. SOC.,1561 (1952). Barrer, R. M., Chem. Ind.. 7, 1203 (1966). Breck, D. W., "Zeolite Molecular Sieves", Wiley, New York, N.Y., 1974. Brecker, K. A., Karge, ti. G., Streubel, W. D.,J . Catal., 28 (3), 403 (1973). Brooks, C. S., Adv. Chem. Ser., No. 102, 426 (1971). Coombs, D. S., Ellis, A. J., Fyfe, W. F., Taylor, A. M., Geochim. Cosmochim. Acta., 17, 53 (1959). Culfaz, A., Sand, L. B., Adv. Chem. Ser., No. 121, 140 (1973). Dornine, D., Quobex, J., "Molecular Sieves", p 10, Society of Chemical Industry, London, 1968. Freund, E. F., J . Cryst. Growth. 34, 11 (1976). Goldsmith, J. R., J . Gaol., 61, 439 (1953). Hansford, R. C., Ward, J. W., J . Catd., 13, 316 (1969). Hopper, J. R., Shigemura, D. S., AIChE J . , 19, 1025 (1973). Hsu, A. C. T., AIChE J . , 17, 1311 (1971). Karge. H. G.,"Symposium on the Mechanism of Hydrocarbon Reactions", p 417, Siofox, Hungary, June 5-7, 1973. Kawasaki, A.. Taniguchi, M.. Nishiyawa, T., Japanese Patent 7 109 593 (Mar 11, 1971); Chem. Abstr., 75, 37612C (1971). Keough, A. N., Sand, L. B., J . Am. Chem. SOC.,83, 3536 (1961).
227
Kladning, W. F., Acta Cient Venez., 26, 40 (1975). McLachlan, D., Jr., "X-ray Crystal Structure", p 10, McGraw-Hill, New York. N.Y., 1957. Meier, W. M., 2. Krist., 115, 439 (1961). Meier, W. M.,"Molecular Sieves", p 10, Society of Chemical Industry, London,
IPBR Miaie,-i.'N., Weisz, P. B., J . Catal., 20, 288 (1971). Norton Co., Neth. Appl. 298606 (CI. Colb) (Aug 10, 1965); Chem. Abstr.. 84, 4856a 11966). Rao, C. N.'R., "Chemical Applications of Infra-red Spectroscopy", Academlc Press, New York, N.Y., 1963. Sand, M. L.,Coblenz, W. S., Sand, L. B., Adv. Chem. Ser., No. 101, 127 (1971). Tatsuaki, Y., Hura, M., Nobuyoshi, H., Bull. Jpn. Pet. Inst., 12 (1970). Voorhies, A., Jr., Hopper, J. R.. Adv. Chem. Ser., No. 102, 410 (1971). WOW, F., Renning, J., East German Patent 83978 (Cl. Colb) (Aug 20. 1971): chem. Abstr., 78, 113434y(1973), Zhdanov, S. P., Adv. Chem. Ser., No. 101, 20 (1971).
Received for review December 29, 1977 Accepted May 18, 1978
Hydrogenation of Dicyanobutene to Adiponitrile with Palladium-on-Charcoal Richard T. Stimek and Howard F. Rase" Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712
The deactivation characteristics of palladium-on-charcoal in the hydrogenation of dicyanobutene (DNB) to adiponitrile have been studied at conditions of industrial interest where all three modes of deactivation occurred simultaneously. The catalyst is reversibly poisoned by H2S generated from the charcoal itself, deactivated by a nitrogenous coke formed from the DNB, and deactivated by sintering. The coke deposit and the H2Saccelerated sintering. A means for reactivating the catalyst using water addition was developed. Currently accepted hypotheses and theories on deactivation along with X-ray, ESCA, and electron microscopy aided in analyzing the complex and interacting deactivation patterns.
It is now generally agreed that catalyst deactivation occurs by sintering, fouling, or poisoning. Many excellent studies have been reported using simple reactions and carefully controlled environments in order to isolate and define a specific mode of deactivation. The insights provided by these efforts, which have been competently reviewed (Butt, 1972), are valuable in analyzing the more complex situation in an industrial reaction, where all three modes of deactivation often occur simultaneously and, at times, interactively. Although references to general deactivation patterns of certain industrial reactions appear, few definitive studies have been presented. However, it is reasonable to assume that, just as in the study of reaction kinetics, observations on complex real systems can lead to new and valuable insights. The research to be described was undertaken not only to define the deactivation characteristics for an industrially important system but also to demonstrate the utility of existing techniques and concepts in discovering causes for deactivation and in developing practical procedures for maximizing catalyst life. The system studied employed a 0.2% Pd-on-charcoal catalyst in the catalytic hydrogenation of dicyanobutene (DNB) to adiponitrile (ADN), an important intermediate in the production of nylon. General Process Description As described by Bailey (1971), Hillyear and Stallings (1956), and Sherwood (1963), 1,4-dicyano-2-butene,which is obtained via the chlorination of butadiene to di0019-7890/78/1217-0227$01.00/0
chlorobutenes followed by cyanation, is hydrogenated in the vapor phase to adiponitrile over 0.2% Pd-on-charcoal catalyst using inlet temperatures in the range of 250-300 "C. The product is obtained by cooling and condensation, and the hydrogen is recycled. High conversion and selectivity are necessary because separation of unreacted DNB is not feasible. One would expect that all three methods of deactivation might occur in this system because of the well-known tendency of unsaturated hydrocarbons to form both thermal and catalytic coke (Oblad et al., 1940), the susceptibility of platinum metals to poisoning (Maxted, 1951), and the sensitivity of palladium to sintering (Pope et al., 1971). However, the specific quantitative effects and possible interactions between modes of deactivation can only be determined by careful experimental studies on the particular system of interest. Accordingly, all three modes of deactivation were investigated. The insights gained suggested improved operating conditions for minimizing catalyst deactivation. Experimental Equipment and Procedures Catalyst. The catalyst used was a nominal 0.2 wt '70 palladium deposited on coconut-shell charcoal. Hydrogenation Reaction System. Conversion studies were conducted utilizing a laboratory hydrogenation system. The hydrogenation reactor was built from two 12 in. long sections of 4-in. schedule 40 stainless steel pipe joined together with a 11/4-in.steel disk. This arrangement 0 1978 American Chemical Society
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divided the system into two sections. A 1 in. diameter by 10 in. long reactor tube protruded 2 in. through the disk to the top 4 in. section, and 6 in. downward to the bottom section. The upper section, which functioned as a vaporizer, was fitted with an atomizer for spraying the liquid feed into the vaporizer chamber. The vaporized feed then entered the inner tube which contained the catalyst. The entire assembly was encased by an electric resistance furnace, and a thermocouple was located at the geometric center of the catalyst bed for temperature measurement and control. Liquid DNB was supplied to the reactor by means of a positive displacement pump and injected into the first reactor section through an atomizing nozzle. The DNB feed was vaporized by contact with preheated hydrogen and nitrogen gases which were also fed through the atomizer. The gaseous reactor effluent was cooled in a natural convection air-cooled heat exchanger and collected for analysis. Prior to start-up the reactor was purged with nitrogen to exclude oxygen. After checking for leaks, the reactor was preheated to 260 "C and a desired H2/N2ratio was established. After steady-state temperatures and compositions were established, the DNB feed was initiated. Composite samples were analyzed for by-product and reactant concentrations by gas chromatography using a combination of FFAP and Carbowax 20M on 60/80 mesh Chromosorb W packed to a height of 3 m in 1/8-in.stainless steel tubing. Reproducibility was 0.5%. Sintering Apparatus. The sintering apparatus consisted of a microreactor submerged in a constant temperature sand bath. The sand is fluidized by preheated air. The apparatus is described in detail by Harrison et al. (1965). Positive pressure was maintained in the microreactor to eliminate the exposure of the catalyst to air at high temperature. A glass bubbler was installed at the outlet of the microreactor and a slight positive pressure of 2 in. of water pressure was established to ensure constant positive pressure throughout the run. A minimal gas flow of 1 cm3/min was required. The microreactor consists of a 3/4-in.Swagelok bulkhead union constructed from type 316 stainless steel. The internal volume of this microreactor was 6.085 cm3. It was fitted with quartz cloth on both ends to support the catalyst. After installing the catalyst, the assembled microreactor was pressure tested at 20 psig with nitrogen using a soap solution for leak detection. When no leaks were detected the microreactor was installed in the sand bath and purged free from oxygen using nitrogen. The sintering gas was then fed to the microreactor, as the sand temperature increased to the pre-established temperature controller set point of 350 "C. Starting at ambient, it took approximately 30 min to achieve the desired temperature. The temperature controller was programmed to shut-off after 6 h, allowing the reactor system to cool to room temperature. Care was taken to allow sufficient time for cooling to prevent oxidation of the palladium and charcoal support by air when the microreactor was removed.
Observed Deactivation Characteristics Preliminary reaction studies revealed rapid deactivation of the catalyst over apparently wide ranges of operating conditions. In order to define, understand, and ameliorate this problem a systematic study with emphasis on the three major forms of deactivation was undertaken. Coking. Reaction studies at 330 "C using recycled hydrogen as summarized in Figure 1 show the formation
w
;10-
over-hydrogenated by-products
160
P
0
4
8
I2
16
20
HOURS
Figure 1. Comparison of catalyst weight gain and deactivation with time (operating conditions: 325-330 O C , 40 psig, 13.5 SCFH H2flow, 3 scfh N2 flow, 60 mL/h DNB flow, 4.4 g of catalyst). Table I. Comparison o f Catalyst Surface Areas and Pore Volume
sample fresh good, used spent steamed ''
surface pore diam- pore volarea, m2/g eter, A'' ume, cm3/g(l (N, ads) (N, ads) (N, ads)
1119.0 7.0 5.3 1141.0
21.75
___
0.533
160.8 29.33
0.0116 0.596
__-
Based on desorption isotherms.
of coke in terms of percentage weight gain of the catalyst with time on stream. Quantitative and infrared analysis of the coke indicated a composition of 70.1% C, 22.4% N, and 6.2% H, and groupings of -NH3, -NH2, -C=C-, C=N- and -C=N. This polymeric deposit is apparently formed largely without catalytic action of the palladium since large amounts of coke of the same characteristics were observed in the presence of the charcoal support alone and also on the walls of the reactor. It should be noted that the weight gain shown in Figure 1 is initially very rapid and then increases only gradually. Typical catalyst relative activity is plotted on this same curve. Two types of observations were necessary for this purpose. In the early portion of a run when average bed activity was adequate to convert essentially all the DNB, activity decline could be detected by following the fraction of over-hydrogenated by-products in the reactor effluent. Thereafter, the more pertinent fraction of unreacted DNB was used as the criterion. Clearly, in the temperature range studied, the continuous decline of catalyst activity cannot be attributed to coking alone. Apparently, the initial rapid decline may be caused by the early rapid coking, but some other mechanisms must play a role in the second phase of deactivation when coking only increases slightly with time, while deactivation continues. The catalyst inspections summarized in Table I, when combined with the weight-gain data of Figure 1, suggest that the coking rapidly causes plugging of all but the largest pores of the charcoal support. The difference in areas between spent and active used catalyst, however, is not sufficient to explain the continuing rapid deactivation noted in Figure 1. Studies of poisoning and sintering were undertaken to seek other possible causes of deactivation. Hydrogen Sulfide Poisoning. Although sulfur compounds were not present in the feed, small amounts of H2S were detected during start-up as shown at "A" in Figure 2 for once-through laboratory hydrogenation (no recycle). The source of this sulfur was the charcoal support which, like any organic product of natural origin, contains varying amounts of sulfur as sulfates depending on its origin and method of preparation. A typical value for the catalyst tested was 500 ppm of S. The sulfate is reduced to H2S during start-up while in contact with hydrogen. The small amount of H2S generated obviously does not
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1978
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Table 111. Sintering Studies (H,, DNB). X-ray Powder Diffraction Measurements of Palladium Crystallite Size" sintering catalyst dura- av crystal. gas bed temp tion lite size 328°C 16 h 121A N, 20%N,-80%H2 328°C 16 h 250A 20% N,-80% H.. 327 "C 16 h 271 A 60 mL/h DNB ... ... unsintered 65 A Based on two or more runs Figure 2. Effect of H,S on DNB conversion (operating conditions: same a8 shown in Figure 1). Table 11. Sintering Studies (H,S). X-ray Powder Diffraction Measurements of Palladium Crystallite Sizeo sintering catalyst dura- av crystalgas bed temp tion lite size nitrogen 350°C 8h 256A 200ppmofH,S 350°C 8h 292A in nitrogen ... ... unsintered 65 A a Based on two or more runs. affect catalyst activity, as shown in Figure 2, during the period zero to 200 h, but the quantity could increase in a recycled hydrogen stream as used for the runs shown in Figure 1and as would he employed in a full-scale plant. To simulate this situation for once-through hydrogen, controlled injection of H,S was employed at approximately 210 and 305 h. These larger concentrations of H,S caused deactivation of the catalyst as noted hy the increase in unreacted DNB in the product. This deactivation, however, did not exhibit the complete reversihility often observed with noble metals when the H,S concentration declines to zero (Maxted, 1951). Some other effect must have produced the permanent decline. Since sintering is a common cause of permanent deactivation, tests were planned to compare palladium crystallite sizes for samples treated under identical conditions of temperature and pressure in the microreactor using atmospheres of nitrogen and H2S in nitrogen. Palladium crystallite sizes were determined using X-ray line broadening techniques. Results of these tests are summarized in Tahle 11. It would appear that sintering has been accelerated by treatment with H2S, and the permanent loss of activity might be attributable to a decline in palladium surface area beyond that which would occur in the absence of hydrogen sulfide. Some irreversible surface complex of palladium and sulfur might also be hypothesized, but ESCA analyses of both active and totally spent catalyst indicate a constant surface sulfur concentration and only PdO on the spent catalyst. Since the deactivation data of Figure 1are based on operation with recycled hydrogen, one may conclude that a portion of the observed long-term deactivation is attributable to H2S poisoning and that H2S will also accelerate sintering of palladium creating permanent losses of active palladium surface. Sintering of Palladium. The sintering tendencies of noble metal catalysts, particularly palladium, have been frequently observed. Directional migration of palladium at temperatures much lower than the Tamman temperature have been reported (Gregg, 19651, and rapid sintering of palladium on charcoal has been observed at temperatures as low as 25 O C in hydrogen and 100 "C under vacuum (Pope et al., 1971). The extent of such sintering is greatly increased for samples containing in excess of 1%
Figure 3. Electron micrograph of spent catalyst, 550000X. (Note aggregated Pd particles at houndary of the charcoal support.) Pd. The sintering characteristics are also very sensitive to the particular reaction system, and for the present must he studied in the laboratory at the conditions of interest. Accordingly, X-ray diffraction studies were made as summarized in Table 111. It was recognized that very small crystallites would not he detected by this method (Klug and Alexander, 1974), but the observed average crystallite size is adequate to indicate changes in size distribution. The average crystallite size obtained by sintering in the presence of DNB and H, is significantly larger than that for H, alone. Since under reaction conditions DNB produces significant amounts of coke, it appears that coke might facilitate palladium migration and thus increase the rate of sintering. Such inferential evidence must be subjected to more detailed study, but the causal connection appears valid. Sintering in the presence of hydrogen hut without DIG3 does produce dramatic growth in crystallite size over that observed for nitrogen alone. This effect of H2 is not surprising, since hydrogen dissolves in palladium to form a nonstoichiometric hydride (Hartley, 1973; Lewis, 1967; Lynch et al., 1973) which has a lower thermal stability than Pd itself and, as in other systems, should sinter more readilv (Clav and Petersen, 1970: Amato et al., 1963: Baily et al.; 196i). Electron microscoue studies of fresh and suent catalvst gave further support to sintering as a major source of catalyst deactivation. Fresh catalyst exhibited uniform distribution of Pd in sizes varying from 30 to 100 A and averaging approximately 60 A. Spent catalyst as shown in Figure 3 exhibited marked Pd aggregation and migration to the exterior surface. A similar phenomenon has been reported for nickel-on-zeolite (Lawson and Rase, 1970). Since as shown in Figure 4, thermal treatment for coke removal requires temperatures in excess of 500 "C, electron micrographs of both spent and fresh catalyst steamed at
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Figure 4. Thermal gravimetric analysis showing coke removal from spent DNB catalyst (nitrogen atmosphere).
Figure 6. Electron micrograph of fresh catalyst steamed at 600 "C far 1 h, 55000OX. (Note presence of very small Pd crystallites.)
Figure 5. Electron micrograph of spent catalyst steamed at 650 "C for 30 min, 55000Ox. (Note additional Pd migration to the solid boundary and breaking of the tar film.)
600 to 650 "C were made to assess the possible consequence of high-temperature regeneration. Additional Pd migration as well as breaking of the tar film occurred in the spent catalyst after only 30 min of steam treatment at 650 "C (Figure 5). Treatment of fresh catalyst at 600 "C for 1 h (Figure 6) caused some P d migration, but substantial numbers of small crystallites remained. After 4 h of treatment, however, migration to the surface was extensive (Figure 7). It is apparent that the high temperatures required for air regeneration will cause excessive sintering of the palladium.
Summary of Deactivation Characteristics The various observations on this system demonstrate that Pd-on-charcoal is subject to all three major types of deactivation when used in the hydrogenation of 1,4-dicyano-2-butene to adiponitrile. Complex interactions between these modes of deactivation further complicate the system. Hydrogen sulfide acts as a temporary poison but when present in significant amounts accelerates sintering of palladium, thereby causing some permanent activity loss. Large amounts of coke are formed initially and reduce the support surface area by 99.9870, causing activity decline. Further sharp declines in activity are attributable to sintering which appears to he accelerated in the presence of coke. This complex interplay of deactivation modes obviously requires extensive investigation to delineate complete mechanistic descriptions. But the insights gained from the observations made in the present study provide adequate background for formulating strategies essential for minimizing deactivation in full-scale plant operation. Minimizing Deactivation. In order t o minimize deactivation in this system, H2S concentration must he
Figure 7. Electron micrograph of fresh catalyst steamed at 600 "C for 4 h, 550 x. (Note advanced Pd migration.)
minimized, excessive temperatures must he avoided, and coking must be reduced or the coke removed. Specifically, in any recycle hydrogen system, the H2S generated during start-up must be removed by scrubbing. Further, careful start-up at low temperature until H2Sgenerated from the catalyst is removed will prevent accelerated sintering due to the hydrogen sulfide. During operation, temperatures of only 15 "C above normal for prolonged periods should be avoided to prevent excessive sintering and coking. There is no way, as is the case in many reactions, to prevent substantial coke formation through temperature control alone, for the necessary high conversion to adiponitrile requires temperatures in the range where rapid coking occm. Hence, a means for periodic removal of coke is needed that does not require temperatures above 450 "C as would he necessary for depolymerization or controlled burning. At such high temperatures sintering would be unacceptably rapid. In order to avoid the high temperatures associated with air oxidation techniques, the reaction of water with coke was considered. The reaction of the usual carbonhydrogen coke is thermodynamically unfavorable at reactor conditions, but the DNB produced carhon-hydrogennitrogen coke reaction with water vapor is favorable. yC.N,H, f xH20 mCO + nNH3
-
Water was tried as a coke-removing agent a t reactor
Ind. Eng. Chem. Prod. Res. Dev., Vol. 17, No. 3, 1978 231
-NORMAL AC*IVITY DECLINE +WATER-H13?3GEN R E A C T VAT @ N Ai i E 23TH H O U R
J
l
I
\
a
,
24
16
32
,
\
1 40
HOViiS
F i g u r e 8. Water-hydrogen reactivation (operating conditions: same as shown in Figure 1). T a b l e IV. R e a c t i v a t i o n Studies. X - r a y P o w d e r D i f f r a c t i o n M e a s u r e m e n t s of P a l l a d i u m C r y s t a l l i t e Size duration sintering
H,-H,O H,-H,O
reg. reg.
n o r m a l run ( n o t reg.) n o r m a l run (not r e g . )
catalyst
of regen-
run
eration
duration
av c r y s t a l l i t e size
2h 2h
__-
36 h 36 h 36 h
281 A 287 A 306 A
___
36 h
302 A
conditions, but no significant improvement in activity or activity maintenance resulted. It was then hypothesized that since the water reaction is slow a t these conditions, the simultaneous presence of hydrogen may be advantageous. As the area around P d crystallites is slowly attacked by the water, hydrogen might be catalyzed by the P d to cause hydrocracking of adsorbed species and thereby aid in removing coke in the neighborhood of the P d crystallites, In this manner a relatively small amount of coke removal would either restore activity or prevent further decline by inhibiting the sintering that seems to be facilitated in the presence of coke. The results of a typical run on the laboratory reactor are shown in Figure 8. Midway in the run the DNB feed was stopped, but hydrogen flow was continued and water was substituted for DNB over a 2-h period. Following this procedure, DNB feed was restored and the activity remained essentially constant thereafter for the remainder of the test ( ~ 2 h). 0 Average P d crystallite sizes were compared for waterhydrogen treated catalyst and untreated catalysts with the
same run times, DNB flow rates, and operating temperatures. The results shown in Table IV indicate an apparent reduced rate of sintering for the treated catalysts. It would seem, in view of the leveling off of activity after treatment and the observed decline in sintering, that the water-hydrogen treatment inhibits sintering by removing coke as previously suggested. Tests of recycle gas revealed a doubling of carbon oxide gases after water-hydrogen treatment from 1300 to 2600 ppm, confirming that reaction had indeed occurred. In the presence of Pd, the CO would ultimately be converted to C 0 2 as the gas was recycled.
Conclusions It is possible to combine fundamental knowledge reported in the literature on catalyst deactivation for simple systems with observations on complex industrial systems to yield useful hypotheses on multiple paths to deactivation. Such hypotheses, though not confirmed in fine detail, can be adequately related in a casual sense to observed behavior so that they prove useful tools in avoiding rapid deactivation and in developing procedures for reactivating or inhibiting deactivating phenomena. Although this study is for a specific industrial system, the approach and techniques used for monitoring pertinent changes in catalysts should prove useful for other systems. Literature Cited Amato, I., Columbo, R. L., Protti, A. M., J . Am. Ceram. SOC.,41, 407 (1963). Bailey, W. J., in "High Polymers", Vol. 24, Part 2, p 757, E. C. Leonard, Ed., Wlley-Interscience, New York, N.Y., 1971. Baily, W. E., Danko, J. C., Ferrari, H. M.,Columbo, R., Am. Ceram. SOC.Bull., 41, 768 (1962). Butt, J. B., Adv. Chem. Ser., No. 109, 259 (1972). Clay, R. D., Petersen, E. E., J . Catal., 16, 32 (1970). Gregg, S.J., "The Surface Chemistry of Solids",Chapter 3, Chapman and Hall, London, 1965. Harrison, D. P., Hall, J. W., Rase, H. F., Ind. f n g . Chem., 57 (2), 18 (1965). Hartley, F. R., "The Chemistry of Platinum and Palladium", Wiley, New York, N.Y., 1973. Hilyear, J. C., Stallings, P. S.,Pet. Refiner, 35 (12), 157 (1956). Klug, H. P., Alexander, L. E., "X-Ray Diffraction Procedures", 2nd od, Wiley, New York, N.Y., 1974. Lewis, F. A,, "The Palladium-Hydrogen System", Academic Press, New York, N.Y., 1967. Lynch, J. F., Clewley, J. D., Flanagan, T. B., Phil. Mag., 28 (6), 1415 (1973). Maxted, E. G., Adv. Catal., 3, 129 (1951). Oblad, A. G., Marschner, R. F., Heard, L., J. Am. Chem. Soc., 62, 2066 (1940). Pope, D., Smith, W. L., Eastlake, M. J., Moss, R. L., J. Catal., 22, 72 (1971). Sherwood, P. W., Ind. Eng. Chem., 55 (I), 37 (1963).
Received f o r review J a n u a r y 3, 1978 Accepted May 30, 1978
Methanol Homologation Reaction Catalyzed by Cobalt Carbonyl Gerald S. Koermer" and William E. Sllnkard Celanese Chemical Company Technical Center, Corpus Christi, Texas 78408
The cobalt carbonyl catalyzed methanol homologation reaction was reinvestigated in a batch unit and, for the first time, in continuous unit experiments. Ethanol was the major product, but more than 20 other reaction products were also identified. The same range of products was observed in both batch and continuous unit experiments; however, selectivity to ethanol and potential precursors was markedly greater in the continuous experiments. The effects of temperature, CO/H, ratio, residence time, solvent, and cobalt concentration were studied.
Introduction Current forecasts emphasize the potential increased availability of synthesis gas derived from coal gasification (Wender, 1976). This has spurred renewed interest in the 0019-7890/78/1217-0231$01.00/0
catalytic formation of chemicals from synthesis gas (e.g., Pruett, 1976). A reaction of interest in this area is the cobalt carbonyl catalyzed reaction of methanol and synthesis gas (methanol 0 1978 American Chemical Society
