Ce-doped SBA-15 supported Pd catalyst for efficient hydrogenation of 2-ethyl-anthraquinone

Hydrogenation of 2-ethyl-anthraquinone (EAQ) is a key reaction in the anthraquinone process for industrial production of H2O2, a green chemical with a variety of applications. Herein, Ce-doped SBA-15 was synthesized via a one-step hydrothermal method with ethylenediamine as pH regulator and explored as the support of Pd catalyst for EAQ hydrogenation. Part of Ce species was incorporated into SBA-15 framework and the rest existed as extra-framework Ce and fluorite phase CeO2 particles. The framework Ce species had a suppressing effect on the aggregation of Pd particles. Their amount increased with lowering Si/Ce molar ratio (SCA) from 50 to 20 and reached a plateau at 30. The content of Ce3+ and the number of oxygen vacancies showed the same trend as the amount of framework Ce with SCA, but monotonously increased with raising reduction temperature from 200 to 600 °C. In addition, hydrogen spillover from metal to support and an increase in the binding energy of Pd were observed. Compared with Pd/SBA-15, Ce-doped catalysts presented significantly improved catalytic performance. Among them, the catalyst with SCA of 30 and reduced at 400 °C exhibited the highest activity (3.8 times of Pd/SBA-15) and selectivity to 2-ethyl-anthrahydroquinone (94.2 % from 91.8 % over Pd/SBA-15).