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The effect of water and NaOH was studied on the hydrogenation of 2-ethylanthraquinone (eAQ) over alumina supported 2% Pd/Al2O3-A and 1.2% Pd/Al2O3-B catalysts. The hydrogenation was performed in a fixed-bed reactor by circulating the eAQ solution (the concentration of eAQ was 60 g/dm3) at 50 °C and 5 bar hydrogen pressure. The egg-shell catalysts were prepared by the precipitation of palladium hydroxide onto the support A (activated alumina, preimpregnated with NaH2PO4) or support B (alumina containing 10% SiO2, and preimpregnated with Na2SiO3). Prior to the hydrogenation, the catalysts were dried and pre-treated with water vapour or NaOH solution. The effect of water and NaOH on the amount of active quinones (eAQ and 2-ethyl-5,6,7,8-tetrahydroanthraquinone, H4eAQ) and in particular the role of such reagents in the consumption of aromatic hydroquinone eAQH2, the primary product of the quinone system of eAQ reduction was examined. The saturation of the phenyl rings in eAQH2 produces H4eAQH2, which is a reactive compound and the hydrogenolysis of the C−O bond in the tautomerized eAQH2 leads to other degradation products. Water and NaOH influence the hydrogenation of C O and the hydrogenolysis of C−O bond but have no effect on the hydrogenation of the aromatic rings. The increase in activity in the former C O to C−OH reduction did not depend of alumina A and B as well as the type of reagent (NaH2PO4 or Na2SiO3) introduced to alumina during the catalyst preparation. These reagents however, influenced the course of degradation processes. Water when introduced to the catalyst exhibited unprofitable effect on maintenance the activity of catalyst during the hydrogenation run. Such an unprofitable role is related to influence of water on the course of reactions yielding degradation products.

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 Na 2 SiO 3 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 °C 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 Na 2 SiO 3 was performed with three Sh, Lg and Vc procedures differing in the method of support drying and the time of support contacting with the Na 2 SiO 3 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.