Iron oxide supported on silicalite-1 as a multifunctional material for biomass chemical looping gasification and syngas upgrading

Abstract

Iron oxide supported on silicatite-1 was synthesized as a novel oxygen carrier for biomass chemical looping gasification (BCLG) with additional functionalities of its reduced form as a catalyst for tar decomposition and an adsorbent for capturing CO2 in syngas. The temperature-programmed-reduction/oxidation profiles showed that the iron oxide supported on silicatite-1 had lower reduction and oxidation temperatures than the iron oxide supported on conventional silica. It was found the iron oxide supported on silicatite-1 was resistant to the formation of strong metal-support interaction and irreversible silicate in the temperature range of 650–1000 °C and exhibited high thermal/chemical stability in a cyclic process. The experimental results showed that at 900 °C, the temperature which maximize the gaseous products, the syngas contained only 0.6% C1-C4 hydrocarbons/oxygenates, 3.5% one-ring aromatics, 5.7% heavier hydrocarbons/oxygenates, and 13.2% steam, meanwhile the overall selectivity towards CO2 and CO was 77.0%. The cracking conversion of toluene over the 15Fe/S-1 was 34.8% at 700 °C. The iron supported on siliclaite-1 had a better catalytic activity in tar decomposition than the iron on a conventional silica support as the silicalite-1 had higher surface area and showed better metal dispersion. As an adsorbent for CO2 capture, the reduced oxygen carrier with 15% Fe had a 1.01 mmol/g CO2 adsorption capacity at 30 °C under 1 bar, which is comparable to other CO2 adsorbents reported in literature. Therefore, the iron oxide supported on silicatite-1 is an effective looping material as an oxygen carrier for biomass gasification, a catalyst for tar decomposition and an adsorbent for CO2 capture.