| 摘要 |
<p>Catalysts consisting of colloidal refractory particles are made by a vapour phase condensn. process and deposited on a carrier, with subsequent calcining. Pref. colloidal dispersions of the particles in sol. form are prepared, in an aq. medium, opt. contg. active catalysts, and the catalysts prepared by applying coatings of the dispersions to a substrate followed by drying and calcining. The particles pref. consists of a refractory oxide, esp. alumina made by flame hydrolysis, with spherical particles of 50-100 angstroms dia. The active catalyst medium is pref. a Pt gp. metal. Used in oxidn. and reduction processes, esp. purification of exhaust gases of vehicles. Also in hydrogenation, isomerisation and combustion systems. Increased activity and stability, with resistance to severe operating conditions and thermal cycles during use. The spherical particles show less tendency to sinter together and, being in non-hydrated form, do not lose their active surface by removal of water during calcining.</p> |
