Oxidation catalyst, reduction catalyst, flammable gas sensor element and catalyst for electrode made of titanium-based metal oxide immobilized with ultrafine gold particles

摘要

PURPOSE:To uniformly and strongly immobilize superfine particles of gold and to increase the catalytic activity by immobilizing the superfine particles of gold whose particle diameter has a specified value on metallic oxide incorporating titanium as the main component. CONSTITUTION:The superfine particles of gold whose particle diameter is 250 angstrom or below are immobilized on a metallic oxide incorporating titanium as the main component. In the method, pH of liquid containing metallic oxide incorporating titanium used for a carrier as the main component is firstly regulated to about 7-11. The aqueous solution of a gold compound is dropt into the aqueous solution thereof under agitation. Gold hydroxide is made to adhere to metallic oxide incorporating titanium as the main component. Then the superfine particles of gold are deposited and immobilized on the surface of titanium-based oxide by heating the titanium-based metallic oxide to which gold hydroxide is made to adhere at about 100-800 deg.C. As metallic oxide incorporating titanium as the main component, multiple oxide containing titanium such as FeTiO3 is used in addition to TiO2. Thereby an oxidation catalyst, a reduction catalyst and a catalyst for a combustible gas sensor and an electrode wherein catalytic activity is excellent are obtained easily and efficiently.