Preparation Of Modified MMT And Its Catalytic Of Low Concentration Ethanol Dehydration To Ethylene At Low Temperature

Ethylene is the basic chemical raw materials and some synthetic drugs' Precursors.With the rapid development of global industry,the consumption of ethylene is increasing.At present,the main source of ethylene is oil cracking,but with the exhausting oil resources and rising prices,this path has been a huge impact.Preparation of ethylene from ethanol dehydration can relieve the pressure of ethylene production;this method has the advantages of simple process flow,low energy consumption and environment friendliness,and is considered to be the most promising route.Therefore,how to effectively use low concentration of ethanol to product ethylene at low temperature has become a hot topic of concern to researchers.In this paper,the montmorillonite was modified by sulfuric acid,polymer and heteropoly acid,the structure was characterized by XRD,BET,FT-IR,TG-DTA and NH₃-TPD.The modified montmorillonite was used as catalysts in low concentration of ethanol dehydrate to product ethylene at low temperature,in order to obtain the catalyst with high performance.The montmorillonite was modified under the conditions of acidification temperature 80 ?,acidification time 7h and sulfuric acid concentration ?=25%.The impurities of montmorillonite were eluted,the lamellar structure was stripped,and the shape of the hole became the accumulation hole of the flaky particles.Specific surface area increased from 21m2/g to 357m2/g,and the pore volume increased from 0.0436 cm3/g to 0.561 cm3/g.After loading the heteropoly acid not only overcame the shortcomings of acid active uneven distribution and so on,but also obtained high ethylene selectivity and ethanol conversion.When the reaction temperature was 300?,?Ethanol=30%,the selectivity of ethylene was about 93% and the conversion of ethanol was 89%.With sulfuric acid modified montmorillonite as matrix,the different amount of polymer could be introduced by ion exchange,and the layered structure of montmorillonite was restored.Interlayer polymers were transformed into the active center after calcination and distributed evenly in the channel.The results showed that the amount of polymer affects the stability and tolerability of the catalyst.When the amount of polymer is 70% of CEC,the catalyst has the high activity.When the reaction temperature was 300?,?Ethanol=30%,the conversion of ethanol was about 97%,and the selectivity of ethylene was close to 100%.In view of the low concentration of bio-fermented ethanol,we need to further reduce the concentration of raw materials.The heteropoly acid was loaded onto the above carrier,and studied its catalytic performance in the ?Ethanol = 20%.The results showed that when the amount of HPW is 15%,acid content and distributions are optimized.Each PW molecule could interact with more surface OH groups,so that the interaction between PW and the carrier enhanced,water resistance increased.Therefore,when the concentration of reactants was reduced,the catalyst still had a good catalytic activity.When the reaction temperature was 300?,?Ethanol=20%,the conversion of ethanol was 98% and the ethylene selectivity was close to 100%.After 12 h,the conversion of ethanol could still be about 95.7%.