Synthesis of Highly Active Ruthenium Sulfide Hydrodesulfurization Catalysts: Effect of Hydrogen in the Activation Process

Abstract

Recently, our group using a new ruthenium precursor has synthesized a ruthenium sulfide catalyst with catalytic activity higher than industrial catalysts [9, 10], in this research work, the structure of the catalyst and the role of different amount of hydrogen in the activation process are evaluated. The catalysts were synthesized following the procedure used in previous work [9, 10] and were activated by 2 hr in a tubular furnace at 673K whit reduction atmosphere of H2S/H2 at 2, 5, 15% of H2S. The resulted catalysts were tested in the HDS of DBT reaction. The HDS studies were carried out in a Parr model 4560 high-pressure batch reactor. 0.25 gram of catalyst was placed in the reactor with a solution of 5 vol. % of DBT in decaline. The reactor was pressurized to 3.1 MPa with hydrogen and heated up until 623 K. After the working temperature was reached, sampling for chromatographic analysis was performed during the course of each run to determine conversion versus time dependence. The materials were characterized by different techniques to know the hydrogen effect in the activation process and ruthenium phase or structure obtained in the catalysts. The table 1 shows the catalytic activity; almost the same catalytic activity for alls catalysts is observed, in spite of very high hydrogen content in activation process for the catalyst 2% (98% of H2). The Z contrast micrographs taken by a HRTEM JEOL JEM2200FS+Cs for 2% catalyst (figure 1a)) show metallic ruthenium inside of the particles which are like core-Shell particles, this metallic structures were not found in 5% (figure 1b)) or 15% catalyst. Nevertheless, the core shell metallic ruthenium particles we found that hydrogen in the activation process are not the main factor to achieve good catalytic activity because the HDS active sites are in catalyst surface located in the shell of the structures.