1969. KOSTELITZ, O., ANDHENSINGER, G. [Catalytic dissociation and Synthesis of Methanol.] Chim. et ind., vol. 42, 1939, pp. 757-773; Chem. Abs., vol. 34, 1940, p. 3572.

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1969. KOSTELITZ, O., ANDHENSINGER, G. [Catalytic dissociation and Synthesis of Methanol.] Chim. et Ind., vol. 42, 1939, pp. 757-773; Chem. Abs., vol. 34, 1940, p. 3572.

Activities of some ZnO preparations obtained by different processes and treated in various ways were studied in the synthesis of MeOH from CO and H₂, and the catalytic action of these preparations after they had been used for the synthesis were studied on the dissociation of MeOH to see what changes were undergone during the high-pressure synthesis tests. When Merck’s pure ZnCO₃ is pressed and then decomposed at 300° in an atmosphere of MeOH, the catalytic power per unit vol. of catalyst increases during dissociation of MeOH with the rate of compression; when the ZnCO₃ is first converted to ZnO by heating at 300° in air and is then pressed, the catalytic power per unit vol. of catalyst at first increases with the degree of compression to a maximum at 1,000 atm., and then decreases at higher pressures. If the activity of the preparations is calculated with reference to the values of total dissociation, the following degrees of activity (activity scale) during the dissociation of MeOH are obtained: ZnO pressed under 1,000 atm. has about the same activity as ZnCO₃ pressed under 2,000 atm.; smithsonite (natural ZnCO₃) has a much lower activity. If the numerical values of CO formed by dissociation of MeOH are chosen as a basis for comparison, ZnO pressed under 1,000 atm. is slightly more active than smithsonite, followed by ZnCO₃ pressed under 2,000 atm. The tests on the synthesis of MeOH showed that smithsonite is the most active catalyst, followed in order by ZnO pressed under 1,000 atm. and by ZnCO₃ pressed under 2,000 atm. and subjected to preliminary treatment in an atmosphere of MeOH vapor at 300°. Smithsonite is a good catalyst without having undergone any preliminary treatment, whereas hydrated ZnCO₃ requires special precautions (preliminary treatment in MeOH vapor at 300°). With smithsonite increase in the velocity of circulation of the gases increases the catalytic power per unit vol. of catalyst; with ZnO the reverse is the case. Tests on the dissociation of MeOH with catalysts that had been used for synthesis showed a considerable decrease in the catalytic power, and the specific activity of these catalysts also seemed to have undergone considerable modifications. ZnO preparations produce chiefly a strong dissociation of MeOH (80-90%) into CO and H₂ and a slight decomposition (10-20%) of the MeOH into secondary products; but, after they had been used for the synthesis of MeOH, they produce little decomposition into CO and H₂ (20-50%), and most of the MeOH is decomposed into secondary products, especially Me formate (15-37% of the initial MeOH). The activity of the catalysts during dissociation of MeOH on the one hand and during synthesis of MeOH on the other is not the same. The study of the catalytic dissociation of MeOH is not a reliable method for determining the most efficient catalysts for the high-pressure synthesis of MeOH. The dissociation reaction seems to be useful merely for furnishing, by means of relatively simple apparatus, a few qualitative data relative to the activity of catalysts for the synthesis of MeOH; to determine the most suitable catalysts it is preferable to carry out synthesis tests under varying conditions of pressure, temperature and quantity of reactants.