Vanadium: an efficient promoter for Ni/Al2O3 based catalysts in Methane Dry Reforming

Methane dry reforming (MDR) is a promising process for syngas production through the valorization of two of the main Greenhouse gases (GHGs): CO2 and CH4 [1]. As a matter of fact, the exploitation GHGs for the production of added value chemical could be one of the possible solutions for atmospheric carbon dioxide reduction. The catalyst plays a key role in this reaction as it should encourage syngas formation by limiting coke deactivation. In this work the attention was focusses on the effects of vanadium promoter in nickel-based catalysts [2]. In particular, the prepared Ni-V/Al2O3, and Ni-V-Ca/Al2O3 were compared to the bare Ni/Al2O3. The fresh and spent catalysts were characterized via N2-physisorption, TPR, XRD, TPO, TEM and SEM techniques to understand the morpho-physical features of the materials and to identify the causes of catalysts deactivation. The catalysts were tested for MDR at the temperature of 650 °C for 100h. The best results were achieved by Ni-V-Ca/Al2O3 with a stable 45% of hydrogen yield, 81% conversion of CH4 and 88% conversion of CO2. The catalytic activity can be well explained by the characterization performed on the catalysts: vanadium and calcium are capable to ensure good metal dispersion and stronger interaction with the support which is mandatory for the stability of the catalyst towards coking and deactivation. As a matter of fact, from spent catalyst is possible to observe that vanadium introduction favors the formation of only superficial carbon nanotubes which do not cover Ni active site. This allows the catalyst to retain its activity for long time.