Study On Green Catalytic Preparation Of Tetrahydrothiophene From Hydrogen Sulfide Waste Gas

As a clean energy,natural gas occupies an increasing proportion in China’s energy structure.However,as the most ideal gas warning agent,tetrahydrothiophene faces a huge market gap in China.At present,the mainstream method of producing tetrahydrothiophene at home and abroad is the tetrahydrofuran thiolation method.This method has high production cost and harsh reaction conditions,which limits the output of tetrahydrothiophene.Therefore,it is of great value and significance to develop a new process with lower production cost and milder reaction conditions.In this work,firstly,the powder heteropoly acid catalyst was used to verify the feasibility of producing 1,4-butanediol as raw material for tetrahydrothiophene.It was found that this reaction was divided into two steps in the same system.The first step was 1,4-Butanediol is dehydrated and condensed into tetrahydrofuran in the molecule.The second step is the reaction of tetrahydrofuran with hydrogen sulfide to generate tetrahydrothiophene.The selectivity of this reaction is very high,and almost no other by-products are formed.When the reaction raw materials and reaction time are sufficient,the selectivity of the reaction can reach 100%.Different heteropoly acids have different catalytic performance advantages in these two steps.When the molar ratio of silicotungstic acid to phosphomolybdic acid is 3:7,the reaction speed of the total reaction reaches the fastest.After selecting the best heteropoly acid catalyst,in order to facilitate industrial use,we loaded the selected powdered heteropoly acid on activated alumina,and optimized a series of process conditions.The best process conditions obtained are as follows:the optimal activation temperature of activated alumina is 600℃,the optimal loading is 6.4%,the optimal reaction temperature is 260℃,and the optimal mixing molar ratio is 3:7.The yield of tetrahydrothiophene is as high as 99.3%.In the actual production process,if the hydrogen sulfide ventilation is increased,the yield of the product can be higher.Not only that,the stability of the catalyst is good.After 42 hours of continuous reaction,the product’s The yield is always stable above 98.5%.