Fabrication of Pd/γ-Al2O3 catalysts for hydrogenation of 2-ethyl-9,10-anthraquinone assisted by plant-mediated strategy

Pd/gamma-Al2O3 catalysts efficient for the liquid-phase hydrogenation of 2-ethyl-9,10-anthraquinone were prepared via an adsorption-reduction method using Cacumen Platycladi extract as both reductive and protective agent. The catalysts were characterized by N-2 physisorption, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The results showed that Pd nanoparticles (NPs) measuring <10 nm were uniformly distributed on gamma-Al2O3. Based on the catalyst with the Pd loading of 0.5 wt.%, H2O2 yield of 85.6% could be achieved at the optimum reaction conditions (H-2 flow rate 40 mL/min, working solution volume 10 mL, hydrogenation time 1.5 h and reaction temperature 40 degrees C). And the reaction temperature was lower than those in the previous reports. Additionally, the catalysts showed much better catalytic activities after pretreatment of the support by HCl, NaOH, Na2CO3 and Na2- SiO3 solutions. Particularly, after gamma-Al2O3 was pretreated with Na2SiO3 solution, the H2O2 yield could reach 96.4% and the catalysts exhibited excellent durability while the degradation products were inhibited to some extent. Furthermore, the Pd NPs thereof did not aggregate after reuse. Therefore, the catalysts assisted by plant-mediated strategy may be promising for the industrial application. (C) 2014 Elsevier B.V. All rights reserved.