Key features of nano NixMg1-xAl2O4 spinel for biogas bi-reforming: CO2 activation and coke elimination

Abstract

Using green and sustainable biogas as raw material to produce syngas (H2/CO≈2) suitable for direct synthesis of green methanol has attracted wide attention, but developing efficient catalysts with high activity/stability remains a big challenge. A series of MgAl2O4 spinel catalysts (denoted as NixMg1-xAl2O4) is designed and applied in biogas bi-reforming. The nano NixMg1-xAl2O4 catalysts were comprehensively characterized by Raman, SEM, HR-TEM, H2-TPR, CO2-TPD, etc. The CO2 activation was verified by in situ CH4-TPSR/CO2-TPO, and the key role of NixMg1-xAl2O4 in coke removal behavior mechanism was further confirmed. Due to the efficient CO2 adsorption/activation and strong metal–support interaction, nano NixMg1-xAl2O4 shows excellent catalytic stability to inhibit sintering and carbon deposition. At reforming conditions of 750 °C, a weight hourly space velocity (WHSV) of 32,400 mL gCat−1 h−1, the Ni0.4Mg0.6Al2O4 catalyst exhibits excellent CH4/CO2 conversion of 91/51 % are achieved, followed by slight decrease after 40 h, and remain basically stable for the next 40 h.