The Study Of Pt Catalyst Prepared By Colloid Deposition Method And Its Activity For Water Gas Shift Reaction

In the recent years, the rapid development of the fuel cell makes the WGS reaction rekindle people’s interest. The supported noble metal catalyst is the recent WGS catalyst research focus. In this paper, Pt nanoparticles with a specific size loaded on different supports by the novel colloidal deposition method. This process of the preparation of the catalyst eliminates the influence of the support on the forming process of supported Pt particles, which has an important significance for the study on the support effect of the WGS reaction.Pt colloid nanoparticles were prepared by reducing chloroplatinic acid (H2PtCl6) in liquid phase. The effect of reductants and the capping agent on the morphology of Pt colloid particles was also investigated. The results show that the Pt colloidal particles with bigger and uniform size can be prepared by ethylene glycol, which is a weak reductant. The capping poly(N-viny1-2-pyrrolidone)(PVP) play a very good role for dispersion. Using NaBH4as a reductant, Pt colloid particles decreases from2.6nm to2.1nm with the increase of PVP amount.Pt catalysts loaded on TiO2, CeO2, ZxO2and Al2O3were prepared by colloid deposition. The physical characterisitic of the catalyst were studied with the characterization methods of UV-Vis absorption spectroscopy, TEM, XRD, and TG. The tubular reactor was used for the activity evaluation of catalysts and kinetic studies. Compared with the impregnation, the Pt/TiO2catalyst prepared by the colloid deposition has higher WGS activity. When the support properties and preparation method is the same, the catalyst with smaller Pt particles has better activity. The WGS reaction activity increased as the order of Pt/TiO2>Pt/CeO2>Pt/ZrO2>Pt/Al2O3, while their reactive activation energy decreased in turn. The support has an important impact on the WGS reaction activity of Pt catalyst.