Oxygen Vacancy-Rich Ni-CeO2 Heterojunction Catalyst for Hydrogenating Halogenated Nitroarenes with High Activity and Selectivity.

Abstract

Halogenated arylamines are important intermediates for the synthesis of dyes, pesticides, herbicides, and other chemicals. One important way to prepare halogenated arylamines is catalytic hydrogenation of halogenated nitroarenes. Ni-based catalysts have been used in the hydrogenation of halogenated nitroarenes but suffer from low activity and dehalogenation side reaction. In this paper, Ni-CeO2/SiO2 heterojunction catalyst with a "raisin-bun" structure was prepared by reverse microemulsion. A built-in electric field and more oxygen vacancies were formed due to electron transfer from Ni to CeO2 as a result of their work function difference. The built-in electric field leads to the heterolytic cleavage of H2, thereby improving the hydrogenation activity. Oxygen vacancies preferentially adsorb and activate nitro groups, inhibiting the dehalogenation side reaction. Through the cooperation of built-in electric field and oxygen vacancy, synchronous enhancement of the activity and selectivity is obtained successfully. This finding provides a new view for the design of non-noble metal-based catalysts with high activity and selectivity.