Simultaneous production of hydrogen and carbon nanotubes from biogas: On the effect of Ce addition to CoMo/MgO catalyst

In this study, hydrogen and carbon nanotubes (CNTs) are simultaneously produced via a synergistic combined process of CO2 methanation (METH) and chemical vapor deposition (CVD) processes using biogas as a feedstock. METH process could upgrade CO2 containing biogas into CH4-rich gas which then decomposed into H-2 and forming CNTs over CoMo/ MgO catalyst by CVD process. The effects of Ce addition to CoMo/MgO were investigated. Comprehensive characterization confirms that all as-synthesized samples composed of well-aligned multi-walled carbon nanotubes (MWCNTs) with a narrow size distribution. The Ce addition improved CoMo dispersion on MgO, resulting in smaller and uniform CNTs. The small addition of Ce into CoMo/MgO catalyst could enhance the production CNTs yield. The higher Ce addition would, however, result in the CNTs yield decreased, attributed to a high basicity of CeO2 surface and a large coverage of CeO2 on the catalyst surface. The I-G/I-D increased with increased Ce addition, while the surface area mono-tonically decreased, attributed to a decrease in defects of nanotubes. In addition, this wisely combined process could result in a remarkable 100%CO2 elimination, while high CH4 conversion of 90% was obtained. The H-2 production yield could gain more than 30 vol% with respect to H-2 in the feed stream. The H-2 yield and purity in the effluent gas stream were approximately 90%. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Hydrogen and carbon nanotubes are simultaneously produced using CO2 methanation and chemical vapor deposition processes. The addition of Ce improves the catalyst performance and enhances the growth of carbon nanotubes. The combined process allows for CO2 elimination and high CH4 conversion rate.