Comparison of Nanosized Gold-Based and Copper-Based Catalysts for the Low-Temperature Water-Gas Shift Reaction

Abstract

In this paper the catalytic performances for the low-temperature water-gas shift reaction of Au/TiO(2) type A (from World Gold Council), Au/CeO(2) (developed at UPV-CSIC), CuO/Al(2)O(3) (from BASF), and CuO/ZnO/ Al(2)O(3) (from REB Research & Consulting) have been compared. The catalysts were characterized by different techniques such as Raman spectroscopy, BET surface area measurements, temperature-programmed reduction, and high-resolution transmission electron microscopy, which gave additional information on the redox properties and textural and morphological structure of the investigated samples. The performances of these catalysts were evaluated in a wide range of operating conditions in a micro packed-bed reactor. It was observed that the presence of reaction products in the feed (CO(2) and H(2)), as well as CO and H(2)O feed concentrations, have significant effects on the catalytic performances. With a typical reformate feed the Au/CeO(2) catalyst reveals the highest CO conversion at the lowest temperature investigated (150 degrees C). However, while in the long tests performed the CuO/ZnO/Al(2)O(3) catalyst showed a good stability for the entire range of temperatures tested (150-300 degrees C), the Au/CeO(2) sample clearly showed two distinct behaviors: a progressive deactivation at lower temperatures and a good stability at higher ones. The selection of the best catalytic system is therefore clearly dependent upon the range of temperatures used.