Production of syngas by CO2 reduction through Reverse Water–Gas Shift (RWGS) over catalytically-active molybdenum-based carbide, nitride and composite nanowires

• Published in: Renewable energy 2021-10, Vol.176, p.251-261
• Main Authors: Dasireddy, Venkata D.B.C., Vengust, Damjan, Likozar, Blaž, Kovač, Janez, Mrzel, Aleš
• Format: Article
• Language: English
• Subjects: Carbon dioxide conversion; Molybdenum carbide (Mo2C) nanowires; Molybdenum nitride (Mo2N) nanowires; Non-noble metal catalyst material design; Reverse water–gas shift reaction (RWGS)
• ISSN: 0960-1481; 1879-0682
• DOI: 10.1016/j.renene.2021.05.051

Transition metal carbides and nitrides with large surface areas are attractive for various catalytic reactions. The synthesis of molybdenum carbide, molybdenum nitride and nanocomposite mixed-phase nanowires with the preserved structural morphology of two different precursor reactant materials by heating in diverse gas mixtures is reported herein. Prepared heterogeneous catalysts were characterized using diffraction, physisorption, chemisorption and microscopic techniques. With XRD and interfacial elemental analysis, performed by a transmission electron microscope, the composition of starting intermediate moieties and products was determined. Ordered grain structure appeared almost independent of applied gaseous compounds and typical domain sizes were comparable. The conversions of CO2 during the reverse water–gas shift (RWGS) were calculated for all measured samples in a wide operation range. Composite Mo2C/Mo2N showed the highest conversion higher than the pure Mo2C with similar site amount and especially larger than Mo2N, which demonstrated a low activity throughout the process. The stability of Mo2C/Mo2N wires was tested at 300 °C and they exhibited an unchanged time-on-stream reactivity over a long period of time (>24 h), withstanding deactivation. In addition, the selectivity towards CO was maintained at around 99%. The comparison of catalyst characterisation before and after RWGS reaction show that there is no major difference in the physical and chemical characteristics of the materials further validate the use of the present catalysts. [Display omitted] •Production of synthesis gas via Renewable CO2 over 1D Mo2N and Mo2C.•99% selectivity towards synthesis gas was obtained below 300 °C.•A high selectivity towards synthesis gas was obtained with varying CO2/H2 ratios.•Mo2N demonstrated the lowest turnover activity for CO2 reduction.•Mo2C/Mo2N showed the highest CO2 turnover activity with long term stability.