Titania-supported catalysts carbon monoxide hydrogenation

The influence of the support is undoubted and spillover was further confirmed by the excess of hydrogen chemisorbed by a mechanical mixture of unsupported alloy and TJ-A1203 above that calculated from the known values for the separate components. It was also observed that the chemisorption was slower on the supported than on the unsupported metal and that the greater part of the adsorbate was held reversibly no comment could be made on the possible mediation by traces of water. On the other hand, spillover from platinum-rhenium onto alumina appears to be inhibited for ratios Re/(Pt Re) > 0.6. In an infrared investigation of isocyanate complexes formed between nitric oxide and carbon monoxide, on the surface of rhodium-titania and rhodium-silica catalysts, it seems that the number of complexes exceeded the number of rhodium surface atoms.The supports have a pronounced effect on the location of the isocyanate bond and on the stability of the complexes, with some suggestion of spillover. 

The reaction order a for carbon monoxide was —0.03, while steam had a positive reaction order b of 0.44. Carbon dioxide and hydrogen showed significant inhibition, as indicated by the reaction order of —0.1 for c and —0.44 for d, respectively [306], The effect of the support on the activity of platinum catalysts was investigated by Rosa et al. [251]. Alumina, ceria, titania and mixed ceria/titania were compared, all containing 0.5 wt.% of platinum. As shown in Figure 4.24, the activity ranking was as follows ... 

---