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 degrees 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 degrees 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).