Chemical looping gasification characteristics of biomass pyrolysis volatiles with Cu/Ni/olivine oxygen carrier for hydrogen-rich gas

This work systematically investigated the reaction characteristics of cotton stalk pyrolysis volatiles with CuO and NiO loaded on olivine (Cu/Ni/O) aiming to produce hydrogen-rich gas. The effect of pyrolysis temperature, gasification temperature, and oxygen carrier to biomass ratio (OC/B) on tar content, gas yield, carbon conversion has been investigated. Lattice oxygen donation capability and catalytic performance of OC was evaluated by comparing the Biomass Chemical Looping Gasification (BCLG) and catalytic gasification. Furthermore, the distribution of oxygen in the pyrolysis products and the distribution of lattice oxygen in the gasification products were investigated. The results indicate that cotton stalk pyrolysis tar is mainly composed of phenolic compounds. The OC can not only decompose most of cyclic compounds but also further reduce the content of monocyclic compounds to hydrogen-rich gas. The release of lattice oxygen from Cu/Ni/O was 56.2 %, which decreased to 47.7 % when steam was introduced at 800 °C. A H₂ concentration of 50.4 % and a H₂ yield of 0.57 Nm³/kg were achieved by both the reaction of tar reforming and the reaction of steam with reduced Fe in Cu/Ni/O. These findings offer new insights and a theoretical foundation for a detailed understanding of the BCLG.