Preparation of thin porous titania films on stainless steel substrates for heat exchange (HEX) reactors

A porous titania film with pores of few micrometer sizes was prepared on a stainless steel support for a composite material of metal and inorganic oxide. The combination of a porous catalyst layer and a metal support improves the thermal conductivity compared with a traditional inorganic powder catalyst by an aid of a metal support. A porous titania film was obtained on a stainless steel support by the electrostatic sol-spray deposition (ESSD) method. Water in the parent sol was a key factor to obtain porous films. These porous films were cracked by a rapid temperature change during the cooling procedure after the deposition by the difference of the thermal expansion rate of stainless steel and titania. The parent sol was aged before a deposition to obtain a flexible structure to keep its structure. The obtained porous films comprised an aggregation of fibrous titania with few micrometer pores by SEM observation. This film was stable for a rapid temperature change. A porous titania film without any cracks were obtained on a stainless steel substrate using the ESSD method by an aging of the parent sol.