Nickel-Stage Addition in Si-MCM-41 Synthesis for Renewable Hydrogen Production

Abstract

Among the countless routes for renewable hydrogen (H2) production, Biogas Dry Reforming (DR) has been highlighted as one of the most promising for the circular bio-economy sector. However, DR requires high operating temperatures (700 °C–900 °C), and, for greater efficiency, a thermally stable catalyst is necessary, being, above all, resistant to coke formation, sintering, and sulfur poisoning. Mesoporous metallic catalysts, such as nickel (Ni) supported on silica, stand out due to their high catalytic activity concerning such characteristics. In this regard, the presented work evaluated the influences of the nickel addition stage during the synthesis of mesoporous catalyst type Si-MCM-41. Two different catalysts were prepared: catalyst A (Ni/Si-MCM-41_A), synthesized through the in situ addition of the precursor salt of nickel (Ni(Ni(NO3)2·6H2O) before the addition of TEOS (Tetraethyl orthosilicate) and after the addition of the directing agent; and catalyst B (Ni/Si-MCM-41_B), resulting from the addition of the precursor salt after the TEOS, following the conventional methodology, by wet impregnation in situ. The results evidenced that the metal addition stage has a direct influence on the mesoporous structure. However, no significant influence was observed on the efficiency concerning BDR, and the conversions into H2 were 97% and 96% for the Ni/SiMCM-41_A and Ni/Si-MCM-41_B catalysts, respectively.