Influence of CoAl2O4 spinel and Co-phyllosilicate structures derived from Co/sepiolite catalysts on steam reforming of bio-oil for hydrogen production

Abstract

Extensive attentions have been paid to develop steam reforming of bio-oil, which was considered as one of the sustainable technologies for producing eco-friendly next-generation energy sources, such as syngas and hydrogen. In this work, the novel catalysts consisted of CoAl2O4 spinel and Co-phyllosilicate are facilely manufactured from xCo/Sepiolite (xCo/SEP) precursors and their catalytic performance has been studied in steam reforming of simulated bio-oil (SRSB). The effects of Co content on the microstructures and physicochemical properties of catalysts are analyzed by various characterizations such as N2 adsorption-desorption, XRD, FTIR, H2-TPR, HRTEM and XPS. The results reveal that the CoAl2O4 phases in these catalysts are evolved gradually from Co-lean nonstoichiometric Co1−xAl2O4−x to Co-rich CoAl2O4 structure with increasing Co loading, subsequently accompanying with the formation Co-phyllosilicate species (CPS) when the Co content exceeds 10 wt%. Among them, calcined 15Co/SEP sample with optimal configuration of Co-Al spinel and CPS leads to its reduced-counterpart possesses fine Co metal nanoparticles, abundant defective Co-Al-spinel and metal-support interface sites. It therefore presents the highest carbon conversion (95.7%) and H2 yield (68.8%) in activity experiment and a slight deactivation in 50 h of stability test during SRSB. The analyses of TG-DSC, XRD and HRTEM are conducted on used catalysts and discover xCo/SEP-derived catalysts exhibit promising coke resistance and metal sintering is the major issue for catalyst deactivation, which mainly caused by particle migration and coalescence mechanism due to the further reduction of CPS.