This study reports a simple, reusable, and recoverable niobium-based heterogeneous catalysts for Biginelli multicomponent reactions. Different methods of catalysts preparation were investigated. For this purpose, HY-340 (Nb 2 O 5 • nH 2 O) and Nb 2 O 5 were chemically and/or thermally treated and investigated as catalysts for dihydropyrimidinones (DHPMs) production. The catalysts were characterized by scanning electron microscopy, high-resolution transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, temperature-programmed desorption of NH 3 , adsorption/desorption of N 2 at −196 °C, and thermogravimetric and differential thermal analysis. The characterization results showed that niobium oxides have the potential to be used as catalysts because of high crystallinity and large surface area. Among the tested catalysts, Nb 2 O 5 chemically treated (Nb 2 O 5 /T) showed the best catalytic performance. In the absence of solvents, 94% yield of DHPMs was achieved. Also, Nb 2 O 5 /T can be reused three times without a significant yield decrease. Additionally, a feasible reaction pathway was suggested based on the Knoevenagel mechanism for DHPM synthesis using niobium-based catalysts.

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After about 30 years of intense ethanol steam reforming study, which was done over several research works in different countries, there are some consensuses: there are many parameters involved, and many reactions occurred. So, this study aims to show that the results obtained for a better understanding of ethanol reforming which usually are found through complex, time-consuming, and expensive chemical techniques could also be obtained in a statistical study of a factorial model in an easier way. Based on previous studies of different research works, where active phase, temperature, and relative compositions of reactants were established, a statistical study was carried out to evaluate the contribution of the active phase (Ni or Cu or both), O2/C2H5OH ratio, and temperature. It was observed that Ni and Cu favor the reaction course of the ethanol reforming, reducing the occurrence of parallel reactions and byproduct formation. Increase of the temperature acted in the same direction, favoring the route of ethanol reforming, specifically, the reforming of methane from previous stages. The presence of oxygen significantly influenced some parallel reactions, such as the partial oxidation of ethanol, the ethylene formation, and the increase of CH4 flow. Thus, the results obtained in this work allowed the production of a scheme of reactionary routes like those in the literature which makes valid the statistical approach for ethanol reforming.