Experimental Study On Chemical Chain Catalytic Gasification Characteristics Of High-sulfur Petroleum Coke Based On Manganese Ore Oxygen Carrier

In the process of Chemical Looping Gasification（CLG）of petroleum coke,how to increase the reaction rate of petcoke gasification is a key issue that needs to be solved urgently.Drawing on traditional petroleum coke catalytic gasification research methods and combining it with the CLG process,this paper modifies the manganese ore as oxygen carrier and petroleum coke as fuel with K-based（K₂CO₃）catalysts respectively,and carries out the experimental study of the conversion characteristics during petroleum coke chemical looping catalytic gasification process.Firstly,based on the fluidized bed reactor,the experiments of petroleum coke of steam gasification and CLG were carried out to compare the difference of petroleum coke gasification characteristics and reveal the influence of the oxygen carrier on the gasification characteristics of petroleum coke.The results show that the increase of gasification temperature significantly promotes the conversion of petroleum coke.The addition of oxygen carrier shortens the reaction time,indicating that the oxygen carrier accelerates the progress of the gasification reaction and enhances the conversion of petroleum while consuming part of the gasification products.With the increase ofφ,which is the ratio of the oxygen needed to combust fuel completely and the oxygen that oxygen carrier can provide,the ability of oxygen carrier to oxidize synthesis gas is enhanced,and the carbon conversion rate is accelerated,but the synthesis gas content and cold gas efficiency are both reduced.Secondly,based on the fluidized bed reactor,the K-based catalyst was introduced to the manganese ore and petroleum coke respectively to study the effects of different temperatures（900℃～975℃）andφ（0.25～1）on the petroleum coke chemical looping catalytic gasification.The results show that K-based catalyst is easy to react with quartz sand as inert material to cause agglomeration of particles in the fluidized bed experiment.After manganese ore being modified by catalyst,the oxygen transfer capacity and reactivity of oxygen carrier are reduced.The fuel being modified by catalyst significantly promotes the conversion of petroleum coke.When the reaction temperature is 950℃andφ=1,the average carbon conversion rate is increased by 1.95 times.But the change of carbon conversion rate after the catalyst being introduced to the oxygen carrier is poor.After the fuel being modified by catalyst,the increase of reaction temperature andφlead to the decrease of H₂/CO while the H₂/CO after oxygen carrier being modified by catalyst increases with the increase of temperature,and decreases with the increase ofφ.Finally,a long-period chemical looping（catalytic）gasification experiment study of petroleum coke was carried out to reveal the cyclic stability and reactivity of oxygen carrier in the process of petroleum coke chemical looping catalytic gasification with the assistance of XRD and SEM-EDS/Mapping.The results show that the oxygen carrier gets active in a degree in cyclic process,and as the cyclic number increases,the relatively stable reaction performance is finally maintained.When the K-based catalyst is loaded on petroleum coke,it significantly catalyzes the gasification process of petroleum coke and the highest average carbon conversion rate（7.8%/min）,the highest H₂ concentration（50%）and the highest H₂/CO（2.32）are obtained.When the K-based catalyst is loaded on manganese ore,the corresponding average carbon conversion rate is 4.39%/min,which is slightly higher than that（3.91%/min）in the chemical looping non-catalytic gasification,the H₂ content is slightly increased,the CO content is slightly decreased,and H₂/CO is about 1.46,which is higher than that（1.25）of the chemical looping gasification.In the long cycles,the oxygen carrier after reaction was detected by XRD,and some new phases,such as Fe₂Si O₄,Mn₃Al₂（Si O₄）₃,KFe Si₂O₆ and K₂Si₄O₉ were formed.The migration behavior of atoms happens in redox process:in the cyclic experiment of catalyst being introduced to petroleum coke,the K atoms on the surface of modified petroleum coke accumulate on the surface of oxygen carrier;in the cyclic experiment where manganese ore was modified,the K atoms on the surface of the modified oxygen carrier are lost as the cyclic number increase and eventually remain relatively constant;Fe and Mn atoms continue to migrate to the surface of the oxygen carrier.