94
Ind. Eng. Chem. Fundam. 1901, 20, 94-96
T = absolute temperature, K V = molar volume of solution given by eq 4,m3 mol-' Vw = molar volume of water, m3 mol-' XL,Xs= lengths of diffusion path in liquid and in membrane, respectively, m x , = mole fraction of ith species x,+, x,- = mole fractions of ith cation and of jth anion, respectively xw = mole fraction of water x + , x_ = mole fractions of cation and of anion, respectively z = variable defined by eq 11 Greek Letters a, p, 7 = components of free energy of activation of diffusing
solute due to cation, to anion and to water, respectively, J mol-' AG*, AGw* = free energies of activation of diffusing solute in electrolyte solution and in water, respectively, J mol-' AD = concentration dependence parameter for diffusivity defined by AD = (Dw- D,)/Dw A+, A- = components of AD due to cation and anion, respectively La, A0 = values defined by La a - y and A13 B - 1 , respectively, J mol-' LaI+,&3,- = values of Acv for ith cation and for jth anion, respectively, J mol 6, = perturbation of free energy of activation of diffusing solute when a water molecule adjoining a diffusing solute are replaced by an ith ion, J mol-' K = Boltzmann's constant, 1.381 X JK X = length of a step for a diffusing particle to move from one equilibrium site to another, m
g , gw
= viscosities of solution and of water, respectively, Pa
S
= ionic valencies of cation and of anion, respectively = density of solution, kg m-3
LJ+,Y-
p
Literature Cited Akgerman, A,; Gainer, J. L. J. Chem. Eng. Data 1972, 77, 372. Glasstone, S.; Laidler, K. J.; Eyring, H. "The Theory of Rate Processes", McGraw-Hill: New York, 1941; Chapter 9, p 524. Gubbins, K. E.: Bhatia, K. K.; Walker, R. D., Jr. AIChE J. 1966, 12, 548. Hayduk, W.; Malik, V. K. J. Chem. Eng. Data 1971, 16, 143. Hung, G. W.: Dinius, R. H. J. Chem. Eng. Data, 1972, 17, 449. Johnson, D. A. "Some Thermodynamic Aspects of Inorganic Chemistry", Cambridge University Press, England, 1968; Chapter 2, pp 37, 41. Jones, G.; Dole, M. J. Am. Chem. Soc. 1929, 51, 2950. Keller, K. H.; Friedlander, S. K. J. Gen. Physlol. 1966, 49, 663. Lusis, M. A.; Ratcliff, G. A. Can. J. Chem. Eng. 1968, 46, 385. McCall, D. W.; Douglas, D. C. J. Phy. Chem. 1965, 69,2001. Podolsky, R. J. J. Am. Chem. SOC. 1958, 80, 4442. Ratcliff, G. A,; Holdcroft, J. G. Trans. Inst. Chem. Eng. 1963, 41, 315. Reddy, K . A.; Doraiswamy, L. K. Ind. Eng. Chem. Fundam. 1967, 6 , 77. Reid, R. C.; Prausnitz, J. M.; Sherwood, T. K. "The Properties of Gases and Liquids", 3rd ed.;McGraw-Hill: New York, 1977; Chapter 11, p 567. Schelbel, E. G. Ind. Eng. Chem. 1954, 46, 2007. Sridhar, T.; Potter, 0. E. AIChE J . 1977, 23, 590. Treadwell, F. P.; Hall, W. T, "Analytical Chemistry", Vol. 2, Part 3, Wiley: New York, 1935; p 704. Wilke, C. R., Chang, P. AICbE J. 1955, 7 , 264.
Received f o r review January 22, 1980 Resubmitted October 31, 1980 Accepted October 31, 1980
Supplementary Material Available: The experimental results on diffusivities of oxygen, viscosities, and densities of aqueous electrolyte solutions (11pages). Ordering information is given on any current masthead page.
COMMUNICATIONS Hydrogenolysis of Organic Substances by Carbon Monoxide-Water Mixture. Examination of Hydrogenolysis of Diphenylmethane on the Various Catalysts Hydrogenolysis of diphenylmethane with CO-H,O mixtures was examined on various catalysts in a batch-autoclave at 400 O C . Alumina-supported molybdenum oxide and tungsten oxide catalysts were found to exhibit the highest activities among the various catalysts examined for this reaction.
Introduction Considerable attention has been paid recently to hydrogenolysis of organic substances by carbon monoxidewater mixtures. Appell et al. (1968 and 1977), Fu and Illing (1976), and Appell and Pantages (1976) applied this process to lignite, bituminous coal, and carbohydrates, respectively. Appell et al. (1969) reported that sodium carbonate, iron sulfide, and mineral matter contained in lignite were effective as catalysts for the liquefaction of lignite. Jones et al. (1978) and Stenberg et al. (1978) have already studied, using sodium carbonate, sodium hydroxide, and iron sulfide, the reduction of various coal-related model compounds. However, their reaction temperatures were comparatively higher. The reactions of the model compounds, therefore, seemed to be similar to thermolysis; nevertheless, the reactions of some compounds, such as diphenylmethane, did not give sufficient conversions for the detailed discussion of the reaction mechanism. Furthermore, there have been no systematic studies on the 0196-4313/81/1020-0094$01.00/0
catalyst available for this hydrogenolysis process, and the function of the catalyst has not been clarified sufficiently. In the present work, hydrogenolysis of diphenylmethane is performed on the various catalysts with a view to finding the catalysts suitable for this hydrogenolysis process. Experimental Section Batch-Autoclave Experiment. All the reactions were carried out in a 146-mL magnetically stirred stainless steel apparatus (SUS-316) at 400 " C for 60 min of nominal reaction time. For most runs, 1 2 mmol of diphenylmethane, 250 mmol of water, and 2 g of catalyst were charged to the cold autoclave; 225 mmol of carbon monoxide was added and then the autoclave was heated; 65-70 min was needed to reach 400 "C. In some runs, 2 g of potassium carbonate or sodium carbonate was used in place of the catalyst. Otherwise, the experiments using nitrogen as an inert gas in place of carbon monoxide was also performed. After the reaction, the autoclave was cooled and then the gas volume was measured. Organic
0 1981 American
Chemical Society
Ind. Eng. Chem. Fundam., Vol. 20, No. 1, 1981 05
Table I. Hydrogenolysis of Diphenylmethane at 400 "C for 60 min of Nominal Reaction Time. (Diphenylmethane Charged: 12.0 mmol; H,O Charged: 250 mmol; CO Charged: 225 m m o l ( 4 MPa Initial Pressure at 25 "C); Catalyst Charged: 2.000 g) product mole yield
a
dpm conv,O
benzene,
toluene,
catalyst
%
%
%
BIT? mol/mol
ext shift,c
run 79 339 66 83 70 72 74 76 202 56 334 69 49
MOO, ( 5 ) wo3 ( 5 ) NiO ( 5 ) coo ( 5 ) Fe203 (25) VZO, (25) ( 3 2 0 3 (25) CuO (25) CO-MO alumina Na,CO,
28.7 56.6 1.3 1.8 1.5 5.0 1.8 1.9 81.9 3.7 1.3 0.4 0.7
13.0 26.5 0.6 1.1 1.0 2.3 0.9 0.9 38.2 2.1 0.4 0.2 0.4
15.7 23.8 0.7 0.7 0.5 2.7 0.9 1.0 39.0 1.5 0.9 0.2 0.3
0.83 1.11 0.86 1.57 2.00 0.85 1.00 0.90 1.02 1.40 0.44 1.00 1.33
53.1 42.7 44.2 45.4 55.6 52.9 59.1 29.0 49.8 45.1 48.4 52.0 29.4
KZC03
none
Diphenylmethane conversion.
Ratio of benzene to toluene.
%
Extent of the water-gas shift reaction.
Table 11. Hydrogenolysis of Diphenylmethane on Molybdenum and Tungsten Oxides Catalysts at 400 "C for 60 min of Nominal Reaction Time. (Diphenylmethane Charged: 12.0 mmol; H,O Charged: 250 mmol; CO Charged: 225 mmol (4 MPa Initial Pressure at 25 "C); Catalyst Charged: 2 g) product mole yield run
catalyst
339 338 337 336 302 34tid 79 351 349 330 84 350d a Diphenylmethane conversion. diphenylmethane in nitrogen.
dpm convf
benzene,
toluene,
%
%
%
cracked matter, %
mol/mol
%
56.6 98.4 99.3 99.5 87.4 96.9 28.7 91.8 98.8 92.7 47.1 68.1
26.5 47.4 51.3 55.7 46.0 61.2 13.0 43.2 45.7 42.6 22.6 34.2
23.8 38.8 33.5 27.7 25.2 23.3 15.7 48.6 52.8 49.9 24.5 18.6
6.3 12.2 14.5 16.1 16.2 12.4 0 0 0.3 0.2 0 15.3
1.11 1.22 1.53 2.01 1.82 2.63 0.83 0.89 0.87 0.85 0.92 1.84
42.7 33.5 29.2 29.3 26.5
Ratio of benzene to toluene.
products and water were washed from the autoclave by acetone. The liquid and gaseous products were analyzed by gas chromatography and mass spectroscopy when needed. In a later section, discussions will be presented on the total conversion percentage of diphenylmethane and on the extent of the water-gas shift concurrent with the conversion reaction. The former was obtained by subtracting the amount of unconverted diphenylmethane from 100. In Table I and I1 are recorded product mole percent yields of benzene and toluene, and of cracked matter when needed, which were normalized to converted diphenylmethane. The extent of the water-gas shift reaction was calculated by dividing the amount of carbon dioxide in gaseous product by the amount of carbon monoxide initially charged, on the assumption that the amount of carbon dioxide produced by the shift reaction is equivalent to carbon monoxide consumption. The precision in the percent conversions of diphenylmethane and the water-gas shift were usually f 2 % . Materials. Catalysts used were prepared by the following procedures. In case of alumina-supported nickel oxide catalyst, 0.973 g of nickel nitrate, NiO(N03).6H20, was dissolved in 100 mL of distilled water. To this solution was added 4.750 g of alumina. The mixture was stirred thoroughly for 72 h and then dried in air a t 120 "C. The dried mixture was calcined in air at 500 "C for 2 h. Other catalysts used were prepared by the same procedures as those of nickel oxide-alumina catalyst. Metal salts used
ext shift,c
Extent of the water-gas shift reaction.
-
53.1 50.5 50.6 50.5 52.9
-
Cracking of
were nitrates for alumina-supported oxides of cobalt, iron, chromium, and copper. For oxides of molybdenum, tungsten, and vanadium, each ammonium salt was used. Alumina used as the supporter for the above catalysts was prepared by the following procedures (Izumi and Shiba, 1963). In order to produce aluminum hydroxide gel, 10% aqueous solution of aluminum nitrate was added gradually with vigorous stirring into the 4 N aqueous ammonia solution up to the pH value of the mixed solution attained 9.0. Gel produced in this way was aged at room temperature for 72 h and filtered under vacuum. Then the filter cake was washed with distilled water until the odor of ammonia disappeared. The gel was then dried in air a t 120 "C for 72 h and calcined in air a t 500 "C for 5 h. Alumina thus prepared was crushed and screened. The fraction of 20-100 mesh of the grain was used. In the following section, the symbols such as Moo3 (5) are used to represent catalysts in which the figures in the parentheses indicate the weight percentages of the metal oxides supported on alumina. In this work, an industrial cobalt-molybdate catalyst supported on alumina (1.20 w t % COO-7.58 wt % Moo3), designated by Co-Mo, was used. The activities of the above mentioned various catalysts were compared with the activity of Co-Mo. This industrial catalyst was provided by National Research Institute of Pollution and Resources, Japan. The catalyst particle was 20-30 mesh. Diphenylmethane purchased from Wako Pure Chemical Industries was better than
96
Ind. Eng. Chem. Fundam., Vol. 20, No. 1, 1981
99.5% pure and was dehydrated with anhydrous sodium sulfate before use. Carbon monoxide was used without any further purification. No contaminants in carbon monoxide were detected by gas chromatography.
Results and Discussion The hydrogenolysis results of diphenylmethane on eight catalysts are given in Table I, in comparison with those on sodium carbonate, potassium carbonate, alumina, and Co-Mo. In each run, the main liquid products were benzene and toluene. The final gas consisted of hydrogen, carbon dioxide, unreacted carbon monoxide, and traces of methane and higher paraffins. In some runs, the amount of carbon dioxide was slightly larger than that of hydrogen. This suggests that a part of the hydrogen produced by the shift reaction was taken up in the hydrogenolysis of diphenylmethane. In the absence of catalyst, hydrogenolysis of diphenylmethane did not practically proceed. The conversion of diphenylmethane was found to be 3.7% on alumina. With sodium and potassium carbonates, diphenylmethane conversion was very low. The catalytic activities of oxides of nickel, cobalt, iron, chromium, and copper were lower than that of alumina, while vanadium oxide showed 5.0% conversion. Oxides of molybdenum and tungsten exhibited high activities for conversion reaction. In the last column of Table I, the extent of the shift reaction in each run is also shown. Even in the absence of catalyst, the extent of the water-gas shift was 29.4%. This reveals that the shift reaction proceeds also on the wall surface of the autoclave. Except copper oxide, all the catalysts listed in Table I promote the shift reaction. On the contrary, among these catalysts, Moos ( 5 ) ,W03 (51, and Co-Mo showed high catalytic activities for the conversion reaction. Table II shows the influence of the contents of tungsten and molybdenum oxides in the catalysts upon their catalytic activities. In the series of tungsten oxide catalysts, the conversion of diphenylmethane goes through a maximum between 10 and 20 wt % of oxide content. The extent of the shift reaction decreased with the increase in oxide content. On WO, (51, the shift reaction was 42.7% which was nearly equal to that of alumina, whereas WOj (25) exhibited 26.5% shift reaction which was approximately equal to that of noncatalytic reaction. This suggests that tungsten oxide has no catalytic activity for the shift reaction. In Table 11, the ratio of benzene to toluene in each run is given. On W 0 3 (20), this ratio is 2.01, which is similar to that in run 348 (cracking of diphenylmethane in nitrogen as an inert gas). The amount of carbonaceous matter deposited on each tungsten oxide catalyst during reaction is shown in Table 11. This may correspond to that of cracked matter of diphenylmethane, since the amount of carbon formed by disproportionation of carbon monoxide was small. Diphenylmethane conversions in runs 338, 337, and 336 are nearly equal to that in run 348. In the series of molybdenum oxide Catalysts, hydrogenolysis of diphenylmethane proceeded considerably, and carbonaceous matter deposited on the catalyst surface was very small. The conversion of diphenylmethane goes through a maximum at 15 wt lo of molybdenum oxide content. The decrease in diphenylmethane conversion above 20 w t lo is considered to be due to the decrease in effective surface area of the catalyst. As shown in run 350 (cracking of diphenylmethane in nitrogen), MooB(15) also exhibited high activity for cracking. However, in the case
of hydrogenolysis reaction on molybdenum oxide using carbon monoxide plus water, the ratio of benzene to toluene ranges between 0.83 and 0.92. This suggests that there is the occurrence of reaction between benzene and methyl groups which may be an intermediate of the methanation reaction from carbon monoxide and hydrogen. The extent of the shift reaction on molybdenum oxide catalyst was virtually independent of the oxide content. By summarizing the results mentioned above, the following conclusion is made. Tungsten oxide catalyst shows no catalytic activity for the shift reaction, whereas molybdenum oxide catalyst does appear to promote the shift reaction. Both catalysts exhibit catalytic activity for the conversion of diphenylmethane to give benzene and toluene; both exhibit activity for cracking of diphenylmethane in the absence of hydrogen to give a preponderance of benzene plus some carbonaceous matter. The latter is possibly due to coking of diphenylmethane or the cracked aromatic products. Molybdenum oxide catalyst, however, shows no cracking activity or coking tendency in the presence of carbon monoxide plus water and the shift reaction, while tungsten oxide exhibits considerable activity for both reactions even in the presence of carbon monoxide plus water, and this activity increases with increasing tungsten oxide concentration in the catalyst. Hence, it is suggested that the shift reaction covers molybdenum oxide with nascent hydrogen which participates in the hydrogenolysis reaction, but suppresses the cracking and coking reactions. Tungsten oxide catalyst, however, does not promote the shift reaction and thus the nascent hydrogen is not readily available to prevent coking and cracking. Therefore, it seems reasonable to suppose that the catalyst, available for hydrogenolysis of diphenylmethane with carbon monoxide plus water, is responsible not only for promoting the water-gas shift reaction but also for promoting the subsequent hydrogenation of diphenylmethane. Acknowledgment The authors express their gratitude to the National Research Institute of Pollution and Resources, Japan, for supplying Co-Mo catalyst, and to Dr. A. Morita of Akita University, Japan, for helpful discussions and advice. Literature Cited Appell, H. R.; Wender, I . Am. Chem. SOC.,Div. FuelChem., Prepr. 1968, 12(3),220. Appell, H. R.; Moroni, E. C.; Miller, R. D. Energy Sources 1977, 3(2), 163. Appell, H. R.; Pantages, P. "Thermal Uses and Properties of Carbohydrates and Lignlns", Academic Press: San Francisco, 1976; 127. Appell, ti. R.; Wender, 1.; Miller, R. D. Cbem. Znd. (London) 1969, 1703. Appell, H. R.; Wender, I.; Miller, R. D. Am. Chem. Soc., Div. FuelChem., Prepr. 1969, 13(4), 39. Fu, Y. C.; Illing, E. G. Id.Eng. Chem. Process Des. Dev. 1978, 15, 392. Izumi, A.; Shiba, T. Nippon Kagaku Zasshi 1983, 8 4 , 699. Jones, D.; Baltisberger. R. J.; Klabunde, K. J.; Woolsey, N. F.; Stenberg, V. I. J , Org. Chem. 1978, 43, 175. Stenberg, V. 1.; Wang, J.; Baltisberger, R. J.; Buren, R. V.; Woolsey, N. F.; Schiller, J. E.; Miller. D, J. J Org. Chem. 1976, 4 3 , 2991.
College of Education Akita University Akita 010, J a p a n Faculty of Engineering Hokkaido Cniversity Sapporo 060, J a p a n
Yasuhiro Takemura*
Hironori Itoh Koji Ouchi Received for review September 5, Resubmitted July 14, Accepted September 30,
1979 1980 1980
