Hydrogenation of 2-ethylanthraquinone on alumina-supported palladium catalysts -: The effect of support modification with Na2SiO3

Hydrogenation of 2-ethylanthraquinone (eAQ) in the fixed-bed reactor was studied in the "Anthra" (AQ) and "All-Tetra" systems on egg-shell palladium profile catalysts (0.7-2 wt.% Pd). Alumina modified with Na2SiO3 solution was used as a support. Solution of active quinones (eAQ and 2-ethyltetrahydroanthraquinone H(4)eAQ) was saturated with hydrogen and circulated through the catalyst bed at the temperature 50 degreesC and the pressure 5 bar. The concentrations of eAQ, H(4)eAQ and degradation product were analysed by the GC method. Modification of the starting support with Na2SiO3 was performed with three Sh, Lg and Vc procedures differing in the method of support drying and the time of support contacting with the Na2SiO3 solution. Efficiency of modification was studied by specific surface area, porosity and Pd concentration profile. Procedure of support modification did not influence appreciably the rate of the main reaction eAQ to eAQH(2) reduction, while evidently affected the course of side reactions consuming desirable eAQH(2) and producing H(4)eAQ and degradation products. Performance of the catalysts in terms of their ability towards hydrogenolytic reactions producing degradation products and decrease in the activity during the hydrogenation run have been correlated with the efficiency of support modification with Si species. The better this efficiency, as in Vc procedure, the better maintenance of catalysts activity during the hydrogenation experiment. (C) 2003 Elsevier B.V. All rights reserved.