A highly stable Pd/SiO2/cordierite monolith catalyst for 2-ethyl-anthraquinone hydrogenation†
Abstract
Catalyst stability is an urgent issue for ethyl-anthraquinone (EAQ) hydrogenation to produce the environment friendly oxidant H2O2. Herein, a highly stable egg-shell Pd/SiO2/cordierite monolith catalyst (PSC) was prepared by an impregnation method. For comparison, a Pd/Al2O3/cordierite monolithic catalyst (PAC) was also prepared. The stability tests of the catalysts were conducted in a continuous trickle bed reactor at 40 °C with a high liquid space velocity of 25 h−1. It turned out that the PSC catalyst obtained a stable H2O2 yield in the 1000 h test while the PAC catalyst deactivated in 100 h. The as-prepared catalysts were characterized by X-ray diffraction (XRD), N2 adsorption, NH3 temperature programmed desorption (NH3-TPD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), H2 temperature programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). N2 adsorption and NH3-TPD results showed that the PSC catalyst had a regular structure and very weak acidity, which contributed to improving the catalyst selectivity and stability. Besides, the lower support calcination temperature was found to be beneficial to improving the hydrogenation efficiency because of higher Pd dispersion and lower Pd loss.