Preparation of a novel fibrous catalyst support

Abstract

A method for preparing wash-coated silica fibres is described. Colloidal silica particles (22 nm) were deposited onto the surface of 2 µm amorphous silica fibres, surface-modified by deposition of a thin film of amorphous silica with a high density of silanol groups and with the charge reversed by adsorption of a water-soluble cationic polymer. This deposition resulted in an increase in specific surface area from 0.9 m² g^–1 for the fibre to 40 m² g^–1 for the fibre with deposited silica particles. Hydrothermal treatment at 750 °C in 100% steam for 24 h fixed the silica particles onto the fibre surface and made them coalesce into a strong porous structure. During this process, the specific surface area decreased from 40 to 30 m² g^–1. Particles of fibrillar boehmite were deposited onto the surface of silica fibres. The boehmite particles were fixed by thermal treatment at 550 °C, during which the boehmite was transformed into γ-Al₂O₃. The specific surface area of the alumina wash-coated silica fibres was 28 m² g^–1. Wash-coated fibres were characterized by nitrogen adsorption-desorption analysis, scanning and transmission electron microscopy (SEM and TEM).