Desulfurization Performance Of Zinc-Cobalt-based Composite Desulfurizer And Their Secondary Utilization For Catalytic Hydrogenation

Coal will still be the one of energy consumption in China for a long time in the future.In the process of clean and efficient utilization of coal,some sulfides will inevitably be produced,mainly including inorganic sulfur hydrogen sulfide and organic sulfur COS and thiophene.These sulfides will not only poison the downstream catalysts and hinder the clean and efficient utilization of coal,but also pollute the environment and harm human health.Therefore,the removal of sulfides is crucial in the process of clean and efficient utilization of coal.Zinc oxide has high desulfurization efficiency and is usually used as a gatekeeper desulphurizer in industry.However,its desulfurization activity is very low at room temperature due to the influence of kinetics.Moreover,ZnO desulfurizer is difficult to regenerate,after use will be abandoned,which not only causes a waste of resources,but also will form solid waste and pollution of the environment.Co₃O₄ can also be used as a desulfurizer for sulfides removal at room temperature,and more importantly,its sulfides can be used as active components or promoters of hydrogenation catalysts.The precursors of hydrogenation catalysts are usually metal oxides,which need to be presulfurization by specific sulfurization agents process before hydrogenation can be realized,which will seriously pollute the environment.Therefore,if can combine the above two processes,that is,the Co species can be introduced into the zinc oxide desulfurizer,so that it can not only desulfurize efficiently at room temperature,but also be reused as a high-value hydrogenation catalyst.It can not only reduce solid waste pollution,but also reduce the presulfurization process,which is of great significance to realizing the effective utilization of resources.In this paper,for the purpose of resource utilization of the spent desulfurizer,the used Zinc-Cobalt-based desulfurizer effects of Zn/Co molar ratio and Fe doping on the structure and desulfurization performance of zinc-cobalt-based desulfurizer,and the hydrodesulfurization activity of the sample after desulfurization was explored,to obtain the composition of desulfurizer with both good desulfurization activity and hydrogenation catalytic activity.The main research contents and the obtained conclusions are as follows:（1）The performance of Zinc-cobalt-based desulfurizer with different Co contents was prepared.The results showed that with the Co contents were 5%,30%,and 70%,the phase composition changed,mainly ZnO,ZnO/Co₃O_4,and Co₃O₄,respectively.When the content of Co is 30%,the desulfurization performance is the best,and the breakthrough sulfur capacity reaches 160.1mg/g.The reason for the improvement of desulfurization performance is that the addition of a small amount of Co increases the dispersion of ZnO and improves the texture properties of the desulfurizer.（2）The hydrogenation experiments of thiophene and COS with zinc-cobalt desulfurizer show that the catalytic performance is positively correlated with the content of Co,and the hydrogenation performance of COS is better than that of thiophene.When Co content is more than 30%,the hydrogenation performance is the best,and the conversion of COS and thiophene can reach 100%and 51%,respectively.It is 4.6 times and 2 times higher than that of commercial Co Mo hydrogenation catalysts under the same conditions,which may be related to the formation of Co S in the process of desulfurization.（3）The effects of different reaction temperature（180℃-350℃）and reaction atmosphere（H₂ and water vapor）on the desulfurizer after use was studied.The hydrogenation properties of COS and thiophene increase with increasing temperature.As low as 200℃,COS conversion can reach 100%,while thiophene conversion is only 79%even at 350℃.It was also found that the increase of H₂content was beneficial to the forward catalytic reaction,while the presence of water vapor produced competitive adsorption with COS,which hindered the forward catalytic reaction.（4）)The influence of Fe on desulfurization performance and hydrogenation performance was investigated by doping Fe with different proportions in zinc-cobalt desulfurizer.The desulfurization performance of the desulfurizer decreases and then increases with the addition of Fe,and the maximum sulfur penetration capacity is 126.8mg/g.Although the introduction of Fe leads to the grain growth of Co₃O₄,it inhibits the grain growth of ZnO and increases the specific surface area of the desulfurizer.The mesoporous volume of 3-4nm in the desulfurizer increased,and the mesoporous volume of 3 nm decreased significantly after desulfurization,indicating that the main reaction of this kind of pore occurred in the process of desulfurization.（5）When Fe modification desulfurizer is used to catalyze the hydrogenation of organic sulfur,the conversion is reduced,but the H₂S selectivity of COS and thiophene is improved.The addition of Fe promoted the crystal growth of Co₃O₄,which led to the low reacting activity with H₂S.