PRETREATMENT EFFECT OF GOLD IRON ZEOLITE-Y ON CARBON-MONOXIDE OXIDATION

A gold/iron/zeolite-Y catalyst was prepared by cation-exchange of iron -impregnated zeolite-Y with a chloroauric acid solution and subjected to various pretreatments prior to being used in carbon monoxide oxidat ion. The physical properties of the pretreated catalyst were character ized by X-ray powder diffraction, UV-Vis diffuse reflectance spectrosc opy, temperature-programmed reduction and temperature-programmed desor ption of carbon monoxide. By comparing to gold/zeolite-Y, the presence of iron oxide was found to hinder the sintering of gold metal during high-temperature treatment. The most active and water-durable catalyst was obtained by heating gold/iron/Y in a stream of humidified inert g as flow. The active sites on the catalyst were proposed to be gold hyd roxide species surrounded by iron oxide.