Development of catalytic ceramic filter candles for tar conversion

Abstract

A catalyst with a high activity in tar conversion, impregnated on the ceramic hot gas filter material was developed. The aim of the experiments was to estimate the light-off temperature of the catalytic filter elements for naphthalene (tar model compounds) conversion and the long-term catalytic stability at a temperature of 700 °C. Configuration of the catalyst was optimized through improvements in coking resistance and long-term stability. The composition and morphology parameters of the filter material were considered. Both the impregnation methods and the composition of the impregnation solution were investigated and validated. The catalyst composed of Ni, Fe, Cr oxides, promoted with Pt (AlSi-Cat43-Pt), and impregnated on the ceramic-fiber filter composed of Al2O3(44%)/SiO2(56%) was found to be the most active catalyst. The designated catalyst was catalytically active at temperatures of about 700 °C, with a naphthalene conversion of around 93% over 95 h without catalyst deactivation. We found that the steam and gas compositions had an influence on the catalytic activity of the filter elements. The same catalytic filter was catalytically active for 115 h at a low concentration of H2O (10 vol%) and H2 (3 vol%) with a naphthalene conversion of 98% at 790 °C without significant deactivation.

Keywords

• Ceramic-fiber composite filter
• Catalytic ceramic filter
• Ni-based catalyst
• Noble-metal promoters
• Tar conversion
• Catalyst long-term activity