Coupling of medium temperature desulfurization and hydrogenation catalysis of Zinc-Cobalt-Molybdenum composite desulfurizer

In the current field of industrial desulphurization, the treatment of solid waste generated by desulphurization agents is facing great challenges. In order to alleviate this pressure, the realization of solid waste resource reuse has become an urgent research topic. In order to better meet this challenge, researchers are working on improving and optimizing desulfurizers. Among them, molybdenum has been widely concerned because of its unique physical and chemical properties. Molybdenum modified Zinc-Cobalt compound desulfurizer was prepared by sol-gel method in order to improve its desulfurization performance and hydrogenation catalytic performance for thiophene after vulcanization. The phase composition and structure of the fresh desulfurizer and vulcanized sample were analyzed by XRD, XPS and nitrogen adsorption/desorption, and correlated with their desulfurization and hydrogenation properties. The results showed that molybdenum species enhanced the desulfurization and subsequent hydrogenation performance of Zinc-Cobalt desulfurizer by influencing the specific surface area, phase composition and forming specific active phase precursor. The introduction of molybdenum species interacts with cobalt to form CoMoO4 species, which is more reactive to H2S, and is also a precursor of CoMoS active phase, which will have a positive impact on desulfurization and subsequent hydrogenation performance. In addition, molybdenum modification improves the specific surface area of the desulfurizer, which is conducive to the exposure of the active site, thus improving the desulfurization performance. Under a condition of 350 ℃, the zinc-cobalt-molybdenum composite desulfurizer with a molybdenum molar fraction of 20% exhibits a breakthrough sulfur capacity of 223.6 mg/g. The formation of active phases of MoS2 and CoMoS after molybdenum modification is the key to the improvement of hydrogenation activity. Under the conditions of 250 ℃, 0.1 MPa pressure, C4H4S mass concentration of (150±10) mg/m3, H2 volume fraction of 10%, and a space velocity of 7800 h−1, the hydrogenation activity of the catalyst with a molybdenum molar fraction of 20% is 2.46 times that of the unmodified catalyst, indicating that molybdenum modification significantly enhances the hydrodesulfurization performance. In this study, the desulfurization ability of desulfurizer was improved by molybdenum modification, and the sulfurized products could be used as high efficient catalyst for thiophene hydrogenation. The coupling of desulfurization and hydrogenation process was realized, which provided a new way for the reuse of waste desulfurizer.