Synthesis of NiMoO4 ceramics by proteic sol-gel method and investigation of their catalytic properties in hydrogen production

Abstract

A proteic sol-gel route was used in the production of NiMoO4 catalysts, which used edible gelatin as a precursor. The triple helix structure of a protein in contact with identical structures acquires an unfolded form, which favors the interaction of the reactive groups of the gelatin (NH3+ and COO−) with the metallic ions (MoO42− and Ni2+). The synthesized catalysts were thoroughly characterized using techniques such as X-ray diffraction, thermogravimetric and differential thermal analysis, Raman scattering, scanning and transmission electron microscopies, UV–Vis spectroscopy, and colorimetry. The results showed that it is possible to prepare the phase-pure α-NiMoO4 polymorph only at temperatures above 700 °C, while a mixture of the polymorphs α and β were obtained at lower temperatures. The synthesized materials calcined at 300, 500, and 700 °C have their catalytic potentials tested in the ethanol steam reforming reaction aiming the production of hydrogen and presented a good performance. The results indicated that among tested materials, the sample calcined at 700 °C exhibited the highest stability, activity, and best selectivity relative to the product of interest.