Microporous exposure on catalytic performance of MoVNbTeOx mixed metal oxides in the oxidative dehydrogenation of ethane

Abstract

The catalytic performance of the non-purified MoVNbTeOx catalyst was optimized by changing the composition of the synthesis gel method in the hydrothermal synthesis process. However, the enhancement in activity was more pronounced for the post-treatment process of the non-purified catalyst. The catalytic performance of non-purified MoVNbTeOx catalysts and phase-pure M1 catalysts in the oxidative dehydrogenation of ethane (ODHE) were enhanced by water agitation post-treatment. The results showed that the phase-pure M1 catalyst obtained by treating the MoVNbTeOx catalyst with nitric acid had an increased activity per unit mass, but with a mass loss of catalyst materials during the purification process. After several days of post-treatment with water agitation, the catalytic activity of the non-purified MoVNbTeOx and the M1 samples gradually increased and stabilized, where both catalysts had a comparable catalytic performance. All the samples were systematically characterized, showing that the catalytic performance of the samples was mainly correlated with the enhanced specific surface area/pore volume. The results show that for the hydrothermally synthesized MoVNbTeOx catalysts, the reaction takes place in the micropores and the key to improve the performance of MoVNbTeOx catalysts is to effectively expose the active sites. Physical post-treatment process that does not require nitric acid or hydrogen peroxide for purification is also effective in enhancing catalyst activity by boosting the active site.