PREPARATION OF A NOVEL FIBROUS CATALYST SUPPORT

A method for preparing wash-coated silica fibres is described. Colloid al silica particles (22 nm) were deposited onto the surface of 2 mu m amorphous silica fibres, surface-modified by deposition of a thin film of amorphous silica with a high density of silanol groups and with th e charge reversed by adsorption of a water-soluble cationic polymer. T his deposition resulted in an increase in specific surface area from 0 .9 m(2) g(-1) for the fibre to 40 m(2) g(-1) for the fibre with deposi ted silica particles. Hydrothermal treatment at 750 degrees C in 100% steam for 24 h fixed the silica particles onto the fibre surface and m ade them coalesce into a strong porous structure. During this process, the specific surface area decreased from 40 to 30 m(2) g(-1). Particl es of fibrillar boehmite were deposited onto the surface of silica fib res. The boehmite particles were fixed by thermal treatment at 550 deg rees C, during which the boehmite was transformed into gamma-Al2O3. Th e specific surface area of the alumina wash-coated silica fibres was 2 8 m(2) g(-1). Wash-coated fibres were characterized by nitrogen adsorp tion-desorption analysis, scanning and transmission electron microscop y (SEM and TEM).