Neighbouring metal and Lewis acid sites: Synergistic cooperators for the selective hydrogenation of C = O in anthraquinone

Abstract

Selective hydrogenation of 2-ethylanthraquinone to 2-ethylanthrahydroquinone is a critical step to produce hydrogen peroxide in industry, and the development of non-noble catalysts with both high selectivity for C = O hydrogenation and superior activity is highly desirable but challenging. Herein, we developed a Ni@Si(5 5 0) catalyst for this reaction, affording 90.7 % conversion and 99.2 % selectivity after reaction at 50 °C for 6 h. The initial reaction rate reached 363.0 μmol·g^–1_Ni·min⁻¹, which is about two-fold higher than those of the previously-reported Ni-based catalysts. Kinetic studies, catalysts characterizations and the adsorption experiment revealed that the catalytic performance of Ni@Si(T) catalysts critically depends on the synergy between the metal site (Ni⁰) and Lewis acid site (positively charged Ni): Ni⁰ accounts for the dissociation of hydrogen, and Lewis acid site is responsible for the adsorptive activation of C = O group. This catalyst design strategy and insights into active sites may provide beneficial guidance for high-performance catalyst design.