Study On Catalytic Pyrolysis Characteristics Of Daliuta Coal/Swelling Coal

Our country’s low-grade coal resources are relatively abundant,and how to realize the clean utilization of coal is particularly important.Due to its high volatility characteristics,low metamorphic coal is more suitable as a raw material for coal pyrolysis.Coal pyrolysis reaction is closely related to coal structure.The study of coal structure and coal pyrolysis characteristics is helpful to reveal the relationship between coal structure and coal pyrolysis products,and is of great significance to the realization of the hierarchical and qualitative utilization of coal.In this paper,FTIR,SEM and XRD were used to analyze the physical and chemical properties of Daliuta coal,methanol（abbreviated as JC）,tetrahydrofuran（abbreviated as SQFN）and methanol-tetrahydrofuran（abbreviated as JS）swelling coal samples,metal-loaded(Ca²⁺,Mn²⁺,Cu²⁺and Co²⁺)coal samples,JC/JS swelling coal samples and simultaneous loading of metals(Ca²⁺,Mn²⁺,Cu²⁺and Co²⁺)coal samples.TG-FTIR,quartz retort pyrolysis and Py-GC/MS were used to analyze how pretreatment effects the evolution of gas,pyrolysis product distribution,and components of tar during the process of heat loss and weight loss.The experimental results show that:（1）In the higher temperature state,the maximum weight loss peak temperature peak of the swollen coal sample is around 470℃,and aliphatic hydrocarbons and CH₄gas escape in the range of 150-350℃in the low temperature stage.The loaded metal has different promotion effects on coal pyrolysis to produce CO escape.With the increase of pyrolysis temperature,the load of metal Ca²⁺makes the amount of released CO from coal heat increase.（2）Compared with DLT,the tar yield of coal pyrolysis products has increased in varying degrees due to solvent swelling.Among them,DLT-JS tar has the highest yield.The main reason is that the swelling effect of the solvent makes the coal structure loose and improves the reactivity of the coal.（3）The initial temperature of swelling pretreatment coal pyrolysis semi-coke gasification increased to different degrees,indicating that different swelling solvent has different catalytic effects on coal pyrolysis semi-coke gasification reaction.Compared with DLT semi-coke,the gasification phenomenon of loaded metal ions occurs first,especially when the largest weight loss peak appears in the pyrolysis semi-coke gasification of DLT-Ca ion coal samples.And the semi-coke gasification phenomenon is more obvious.So it is the first to occur the gasification reaction.And we found the same pattern in simultaneous swelling and simultaneous loading of metal Ca²⁺pyrolysis semi-coke.（4）Compared with DLT,the content of aromatic hydrocarbons in pyrolysis products of swollen coal samples is different,and the relative content of phenol and methylphenol in acidic chemicals is also reduced to a certain limit.After loading metal ions,the relative content of acidic chemical substance dimethylphenol in the coal pyrolysis product decreases to a certain extent,and the loading of metal Co²⁺makes the relative content of benzene and xylene in the coal pyrolysis product gradually increase.（5）Compared with DLT,the Cu²⁺ion coal sample requires the lowest activation energy in the second stage,which indicates that the Cu²⁺ion coal sample has the best catalytic effect.The swelling and simultaneous loading of metal ions requires less energy in the second and third stages of the pyrolysis reaction.The magnitude of the activation energy indicates the excellent catalytic effect of the reaction.Therefore,the catalytic effect is Cu²⁺>Ca²⁺>Mn²⁺>Co²⁺.