Effects of NaCl on Pt/ZrO2 catalysts for selective hydrogenation of crotonaldehyde

A series of NaCl-modified Pt/ZrO2 catalysts were prepared and tested for vapor phase selective hydrogenation of crotonaldehyde. It was found that the reactivities of the catalysts increased with NaCl contents, with the highest selectivity to crotyl alcohol (60%) at a NaCl content of 1%. Ammonia temperature programmed desorption and Fourier transmission infrared spectra of pyridine adsorption results indicated that the strengths of surface Lewis acids of the catalysts were weakened with increasing NaCl contents, such weakening was responsible for the enhancement of the reactivity. Diffuse reflectance infrared transform spectra of CO adsorption and X-ray photoelectron spectrometer results suggested that increased electron density on Pt species with the NaCl modification was responsible for the enhanced selectivity. However, high NaCl content (>3%) in the catalyst resulted in the growth of Pt particles and fewer interfacial Pt sites contacting with the surface Lewis acid sites, such changes were unfavorable for the selectivity. (C) 2010 Elsevier B.V. All rights reserved.