Preparation And Modification Of Catalysts For Methane Anaerobic Aromatization

With the rapid development of the industry,our country’s demand for benzene is increasing day by day.At present,obtaining benzene from the petroleum route is the mainstream route.However,the international environment is becoming more and more complex,and international conflicts are becoming more and more serious.As a major manufacturing country,my country’s demand for benzene continues to increase.,oil resources are relatively scarce in my country,and the situation of "rich coal,lean oil,and little gas" continues,which is a potential threat to my country’s energy security;)The development of technology can well solve the problems encountered at present.In recent years,the development of unconventional natural gas and combustible ice in my country and internationally has been gradually accelerated,and the proven reserves have been increasing.If these resources can be effectively utilized,it will have a profound impact on our country.After about 30 years of development,MDA technology is now close to industrial production,but there are still some problems that need to be solved urgently.The catalyst coke seriously leads to deactivation,which seriously affects the industrialization process of MDA reaction.In this paper,green,non-polluting and low-cost HZSM-5 molecular sieves were prepared by a template-free method,and the effect of molecular sieves with different silicon-alumina ratios on the MDA reaction was explored.The active metal Mo was impregnated on HZSM-5 with ammonia water to improve the performance of the catalyst.The effects of ammonia concentration,ammonia treatment time and ammonia treatment temperature on the reaction of MDA were respectively explored.The research has led to the following conclusions:The HZSM-5 molecular sieve synthesized by the template-free method has a smooth surface,regular morphology,uniform particle distribution,and mainly micropores.The preparation method is simple,the preparation cost is low,and it is green and pollution-free.After loading Mo,it was applied to the MDA reaction.,the selectivity of benzene and aromatics are up to 60.0% and 70.0%,respectively.The Mo/HZSM-5 catalyst was prepared by immersion in ammonia water,which greatly enhanced the stability and anti-coking performance of the catalyst.The morphology of the Mo precursor was changed by immersion in ammonia water,and the size of the ammonium molybdate ion was reduced,so that the Mo precursor entered the The resistance of the catalyst pores is reduced,and more Mo precursors can enter the pores of the molecular sieve to generate active sites and improve the catalytic performance of the catalyst;in addition,the pores of the molecular sieve will also be etched during the process of impregnating Mo with ammonia water.The pore volume of the catalyst increases,which reduces the resistance of the product to diffuse out of the molecular sieve and reduces the amount of carbon deposition on the catalyst.In the MDA reaction,the selectivity of benzene and aromatics reached 65.0% and 80.0%,respectively.