Hydrodesulfurization of DBT with bulk sulphide catalysts. Reaction mechanism

Abstract

The major problem of modern petroleum refining is the increasing efficiency of hydrogenation for producing high quality distillate fuel. Today hydroprocessing catalysts occupy a leading position among the other catalytic systems. When applying traditional supported catalysts the heavy oil components of petroleum disperse systems with a high molecular weight precipitate on the surface of the support granules and block the working surface of pores. Mesoporous supports with a relatively high pore size is not always effective. So, the annual increase in the proportion of publications relating to the massive (unsupported) sulfide catalysts of hydrogenolysis reflects the changes in the research direction. The relevance of the research is in urgent need to develop new methods and approaches to the synthesis of original, massive domestic sulfide catalyst systems with a high degree of activity and efficiency in hydrotreating of oil fuel fractions, a preparation of which is based on use of energy-saving and hi-tech approaches. The main aim of the research is to synthesize bicomponent bulk sulfide catalysts in a single step by a solid phase method, to investigate their activity in a model hydrogenolysis reaction of dibenzothiophene, to determine the composition of products and the most probable mechanism of the reaction. Methods of research: transmission electron microscopy, UV spectroscopy, X-ray fluorescence analysis, gas chromatography-mass spectrometry. Results. For the first time the authors have obtained in a single step the highly active bicomponent catalysts by direct mechanochemical combination of coarse cobalt (nickel) powders and molybdenum disulfide as promoter and precursors of the active component respectively. The systematic studies were performed to determine the effect of the ratio of initial reagents, duration of mechanoactivation on activity of dibenzothiophene hydrodesulfurization. The authors determined the optimal conditions for preparing Ni- and Co-containing systems providing ultra-low sulfur content (1-3 ppm) in a model dibenzothiophene hydrogenolysis and the composition of the reaction products. It was shown that the dibenzothiophene hydrogenolysis occurs concurrently with cracking and hydrogenation routes.

Keywords

• bulk sulfide catalysts
• coarse powder
• mechanical activation
• model reaction of hydrogenolysis