| Today that environmental pollution problems are still outstanding, accordingly the regulations of many countries in the world has become increasingly stringent for the sulfur content of coking benzene. However, in our existing coal industry, the content of sulfur compounds of coking benzene is relatively higher, which is difficult to meet the national standard. And also the presence of these sulfur compounds greatly limits the use value of coking benzene. Coking benzene is another important source of commercial benzene other than petroleum benzene. In the current situation that the world petroleum resource was depleting gradually day by day, this highlights the importance on coking benzene. Therefore, an energy-saving, high efficient and environment-friendly method to remove sulfur compounds from coking benzene should be developed. And it is currently a big problem to be solved to fully utilize China's abundant resources of coking benzene. In this study, we chose and studied several different methods to remove thiophene from coking benzene and optimized the desulfurization process, developing an efficiently method to remove thiophene at mild conditions. Therefore, this experiment is to find the best one from the results of different liquid acid treatment for coking benzene, and then cheap kaolin used as a carrier to prepare a series of solid acid catalysts. The modified kaolin solid acid catalysts are applied in the desulfurization reaction of coking benzene.At first part of this paper, a detailed literature review was summarized from those aspects, such as the source, composition and application for crude benzene, thiophene sulfur compounds, the study progress for coking benzene desulfurization technology and the application of the solid acid catalyst in the desulfurization of coking benzene. Firstly we do an overview for some basic common sense of coking benzene, which leads out the significance of coking benzene desulfurization. And then we analyze and sum up the advantages and disadvantages of some common desulfurization methods used at this stage. At last, we has also done a detailed introduction about the solid acid desulfurization applied in the coking benzene desulfurization, including the origin, development, application and existing problems of the solid acid catalyst, especially doing a thorough research for clay and metal oxide solid acid catalyst used in the coking benzene desulfurization.The second part is to specially study the pickling refined method. In the experiment, we used different acids to handle coking benzene and investigated the formation dosage of acid tar after different acids treatment, the loss rate of coking benzene, thiophene removal. The best treatment conditions have been found by optimizing the treatment conditions, which reduce pollution and conserve the resources. At last of this part, the solid acid catalysts prepared by acid treating kaolin are also applied in the desulfurization of coking benzene.In the third part, we prepared a series of solid acid catalysts by using sulfuric acid to modify the kaolin in different conditions, and which were used in the catalytic alkylation desulfurization experiments of benzene coking. In the experiments, we investigated the preparation condition and the desulfurization reaction conditions, and ultimately obtained a higher acidity of solid acid catalysts and optimal reaction conditions. This study showed that the catalyst prepared in the optimal conditions is very efficient. And it is valuable to further study the mechanism.In the fourth part, we prepared a single metal, double metal and three-metal oxide modified kaolin solid acid catalysts by different methods, such as dipping, solid ground mixing, precipitation. And further, we have done the evaluation for those catalysts in the desulfurization experiment. This process is still carried out by alkylation methods, in which acetic anhydride is used as an additive. Study found that the catalyst prepared by metal oxide modified kaolin is less effective. |
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