Obtenção e caracterização de nanocatalisadores de WC e Ni suporatados em Al2O3 e MCM-41

Abstract

The search for new sources of renewable energy is a global concern for increasingly sustainable development. Among renewable energy sources, hydrogen (H2) is considered an alternative to fossil fuels due to its minimal environmental impact. This study aimed to obtain and characterize nickel (Ni) and tungsten carbide (WC) catalysts supported on alumina (Al2O3) and MCM-41 as potential candidates for hydrogen (H2) production through dry methane (CH4) reforming. Various transition metals such as Co, Pd, Pt, Ru, Rh, Ir, and Ni can be used in the reforming reaction. Tungsten carbide exhibits behavior similar to Pt in various catalytic reactions, resulting from the modification of tungsten's electronic structure through carbon addition. In this context, we successfully synthesized (Ni10%wt.) and (WC10%wt.) catalysts supported on Al2O3 via incipient wetness impregnation with distilled water, as well as (Ni10%wt.), (WC10%wt.), (Ni2%wt.-WC8%wt.), (Ni5% wt.-WC5%wt.), and (Ni8%wt.- WC2%wt.) catalysts supported on MCM-41 via incipient wetness impregnation with ethanol. The (WC) used in the study was produced through carbothermic reduction of ammonium paratungstate (APT). The obtained material was characterized using X-ray diffraction (XRD), X-ray fluorescence, Raman spectroscopy, BET nitrogen adsorption-desorption, and scanning electron microscopy (SEM). Based on the results, it was concluded that the WC synthesis process was efficient, producing nanoscale carbides (15.5nm) with irregular particle shapes and sizes. Incipient wetness impregnation proved to be an effective method for all obtained catalysts, with the nickel phase showing better dispersion on both alumina and MCM-41 supports than the WC phase. However, when both active phases (WC-Ni) were present, the dispersion on the supports improved significantly for the WC active phase. The catalyst (Ni10%wt./Al2O3) exhibited a specific surface area of 3.60 m²/g, while the (WC10%wt./Al2O3) catalyst had a specific surface area of 2.2 m²/g. The Ni10%wt./MCM-41 catalyst had a specific surface area of 588.56 m²/g, whereas the WC10%wt./MCM-41 catalyst showed a surface area of 870.63 m²/g, increasing significantly compared to the nickel active phase (Ni10%p/MCM41).