| Photoassisted water-gas shift reaction and nitric oxide and ethylene chemisorbed on Pt/TiO(,2), CO hydrogenation on Ni/TiO(,2), Ni/Ti(,2)O(,3) and Ni/Al(,2)O(,3), and carbon monoxide chemisorbed on K/Pt/TiO(,2) were studied.; In the first part, the variation of the rate of the photoassisted water-gas shift reaction over platinized titania with changes in catalyst preparation has been studied. The reaction rate does not depend on the method of Pt deposition, is first order in light intensity, is not dependent on the chemical state or the Pt loading above 2wt%, depends on reduction of the titania and is strongly dependent on the surface concentration of NaOH. From this work, we conclude that when NaOH is present the rate limiting step is the reaction of photoproduced holes with surface OH('-) ions.; In the second part, the chemisorption of NO on platinized TiO(,2) was studied at 300K by Fourier transform infrared spectrometry. Two absorption bands at about 1760 and 1700 cm('-1), which have been assigned as NO adsorbed on Pt open sites and on close-packed sites respectively, were found to vary in intensity with reduction and O(,2) pretreatment. Both nitric oxide and ethylene uptakes are also diminished on reduced, SMSI, Pt/TiO(,2).; The third part presents CO hydrogenation on Ni/TiO(,2), Ni/Ti(,2)O(,3) and Ni/Al(,2)O(,3). In the IR study, the 2050-2057 cm('-1) band is closely related to the adsorbed species suggested at high pressure in the uptake study. The results of a methanation study show no direct correlation between SMSI and methanation activity. However, there is a strong correlation between the methanation activity and the equilibrium constant for CO uptake at high pressure. This correlation suggests that the suface H(a) concentration is rate limiting in methanation.; In the fourth part, the chemisorption of CO on potassium promoted platinized titania was studied at 300K by Fourier transform infrared spectrometry and uptake methods. Catalysts were also examined by XPS. The total amount of carbon monoxide uptake is diminished on potassium promoted Pt/TiO(,2). Potassium may block some adsorption sites for CO. However, CO chemisorbed on the residual sites is found to adsorb more tightly. |
