Catalyst copper/zinc oxide/alumina

Chinchen GC, et al. Mechanism of methanol synthesis from CO2/CO/H2 mixtures over copper/zinc oxide/alumina catalysts - use of 14C-labeled reactants. Appl Catal. 1987 30(2) 333-8. 

In 1973, Leonov et al. 61) introduced a kinetic rate equation for the low-pressure copper-zinc oxide-alumina catalyst for temperatures between 220 and 260°C. The rate equation was proposed to be... 

Denny and Whan (26) also reviewed various contrasting reports on the effects of C02 on the synthesis and emphasized that any complete kinetic expression should include a term involving the partial pressure of C02. A rate equation that does contain an empirical C02-dependent term for the copper-zinc oxide-alumina catalysts has been presented in 1980 by Andrew (27) in the form... 

The activity of several of these catalysts was much higher than that of a commercial copper/zinc oxide/alumina catalyst. In particular they were active at remarkably low temperatures. This was very puzzling because their dispersion was much lower surface areas of lm2/g instead of 30-40, copper particle size 30-50 nm instead of 10-20. 

The low temperature shift catalyst functions 100-200°C below the temperature of the high temperature system and is operated between 210 and 240°C. The catalysts used in this process are copper/zinc oxide/alumina materials. The composition and method of preparation of the copper-based precursors are crucial in determining the final properties of the catalyst. The typical composition of a commercial copper/zinc oxide/alumina catalyst may be 33% CuO, 34% ZnO, and 33% AI2O3. Although the ability of copper/zinc oxides to catalyze the WGS reaction was recognized in the late 1920s, routine usage in commercial plants did not occur until 1963. Until that time, the susceptibility of the catalyst to... 

Wiese et al. reported full conversion of methanol over a commercial copper/zinc oxide/alumina catalyst, with no further specifications given, at 280 °C and a maximum weight hourly space velocity of 5 LH2 (h gcat) in a tubular fixed bed [154]. This is within the usual range of space velocities for this type of catalyst. The power density of the fixed catalyst bed was calculated to be 12.5 kW L . The increase in carbon monoxide concentration at partial load, which is typical over copper/zinc oxide catalysts, is illustrated in Figure 4.6. Naturally, the lower the space velocity, the higher the conversion becomes. As soon as the space velocity is considerably below the value required to achieve full conversion, selectivity of the catalyst towards water-gas shift... 

Mass transport limitations also increase the selectivity of copper/zinc oxide/alumina catalysts towards carbon monoxide in larger particles [149]. Purnama et al. therefore proposed catalyst coatings as a means of reducing carbon monoxide formation. 

Dimethyl ether formation was also observed by Men et al. over copper/zinc oxide/ alumina catalysts at lower values of the weight hourly space velocity [ 163]. A low weight hourly space velocity of 10.9 L (h gcat) was required at a S/C ratio of 2 in order to gain full methanol conversion vtithout formation of any by-products such as dimethyl ether. Under these conditions, around 1.5 vol.% carbon monoxide was formed. 

Bowker, M., Hadden, R.A., Houghton, H., Hyland, J.N.K., and Waugh, C.J. (1988) Mechanism of methanol synthesis on copper/zinc oxide/alumina catalysts. J. Catal, 109, 263-273. 

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