Hydrodesulfurization of Dibenzothiophene Catalyzed by Supported Metal Carbonyl Complexes. (Part 6). Effects of Supports on Activities of HDS Catalysts Prepared from Supported Ruthenium Carbonyl-Cesium Hydroxide Systems.

Abstract

In hydrodesulfurization of dibenzothiophene (DBT) catalyzed by supported ruthenium carbonylcesium hydroxide systems after presulfidation, the effects of various supports such as Al2O3, SiO2-Al2O3, SiO2, TiO2, NaY zeolite on the catalytic activity and product selectivity were investigated. In the absence of cesium, the conversion of DBT decreased in the order SiO2-Al2O3>Al2O3>TiO2>SiO2>NaY zeolite. When cesium hydroxide was added to the catalysts derived from supported Ru3(CO)12, the conversion of DBT increased remarkably with the use of Al2O3, SiO2-Al2O3, and SiO2 and reached the maximum values at Cs/Ru=2, 3 and 2, respectively. The conversion, however, decreased in the order Al2O3>SiO2>SiO2-Al2O3. Further addition of cesium decreased the activity. In contrast to this, when NaY zeolite was used, the conversion of DBT did not increase with the addition of cesium. For obtaining a high catalytic activity, it was essential to load the ruthenium hydride complex Cs[HRu3(CO)11], obtained after reacting Ru3(CO)12 with cesium hydroxide, onto the support. In the supported Ru3(CO)12-cesium hydroxide systems, biphenyl was produced selectively. XP spectra showed that the addition of an appropriate amount of cesium stabilized the ruthenium sulfide on the support even under hydrogen pressure.