Microwave Assisted Catalytic Pyrolysis Of Lignite For Oil Production

As the basis of human survival and development,the clean and efficient utilization of energy has always been the focus of people's attention in social development.At present,the leading energy source supporting China's sustainable development still is traditional fossil energy,especially the abundant coal resources.However,with the decrease of limited high-quality coal,the clean and efficient utilization of the low-grade coal with large proportion is especially important.Lignite,as a typical low-grade coal,is mainly used for direct combustion power generation currently,with low efficiency and serious pollution.In order to relieve environmental pressure and meet the energy demand of rapid economic development,clean and efficient utilization of lignite has been one of the important research topics in China.As a new pyrolysis method,microwave pyrolysis is widely used in biomass,coal,municipal sludge and other pyrolysis processes due to its advantages of energy-saving,high-efficiency,selective-heating,clean and environmental protection.To increase the total tar yield and the light component content,microwave assisted catalytic pyrolysis were conducted in this study.In this study,a self-made microwave pyrolysis device and low-temperature pyrolysis device were used to investigate the effect of catalysts on the total tar yield and light component content with Mengdong lignite.FTIR?GC-MS analysis of tars and FTIR analysis of chars were studied.The optimal microwave pyrolysis power is 700W and the optimal pyrolysis temperature is 700?by maximum tar yield.Ca/Fe@Al₂O₃ catalysts with different Ca/Fe molar ratio were prepared,and the effects on total tar yield and light components on microwave pyrolysis and conventional pyrolysis were studied.The results show that the total tar yield under 3Ca/Fe@Al₂O₃ catalytic effect was highest 8.23%with the light component content of 57%on microwave pyrolysis,and the light component content under 9Ca/Fe@Al₂O₃ catalytic effect was maximum 67%with the total tar yield of 7.81%;The total tar yield and the light component content were also greatly improved on conventional pyrolysis,but the maximum total tar yield is only 3.07%with the light component content of 50%,far behind that on microwave pyrolysis,and indicating that microwave catalytic pyrolysis is a more effective method to improve the tar yield and the light component content.Fe₂O₃@ZSM5 catalysts with different Fe₂O₃ loading were prepared.It was found that the Fe₂O₃@ZSM5 catalyst with 10%Fe₂O₃ loading has better effect than 9Ca/Fe@Al₂O₃,both the total tar yield of 9.47%and the light component content of 70%were highest on microwave pyrolysis;While the 5%Fe₂O₃@ZSM5 catalyst has the better effect on conventional pyrolysis,This is because the conventional catalytic mechanism mainly depends on the pore channel and acid site.Excessive load of Fe₂O₃ will cause the pore channel blockage,resulting in the decline of catalytic activity.Besides the pore structure of molecular sieve,the microwave hot spot effect and the dielectric loss factor of catalyst are also important.As a result,the optimal Fe₂O₃ loading capacity,tar yield and light weight of catalytic pyrolysis under different heating modes are different.