Study On The Secondary Reaction Of Shendong Coal Pyrolysis Volatiles Passing Through The Semi-coke Layer

China is a big producer and consumer of coal resources.How to cleanly and efficiently use coal resources is the focus of scholars' research.Through pyrolysis technology,coal can be transformed into high value chemical products and high calorie gas.At the same time,coal can also remove sulfur,nitrogen and others.Therefore,research on pyrolysis technologies is a general trend.Pyrolysis is the first step in the thermal conversion of coal.It is always accompanied by the occurrence of secondary reactions in the pyrolysis process.The secondary reactions have great influence on the composition of the pyrolysis final products.Therefore,this article mainly explores the effect of secondary reactions on the composition and distribution of pyrolysis products when volatile matter passes through char.It was found that under N₂atmosphere,the char can reduce tar yield.At 500°C,the tar yield was decreased by 7.1%;the gas yield was increased,the increase was the most at 550°C,and the gas yield was increased.9.9%;Under H₂ atmosphere,tar yield can be improved.The effect of the tar yield at 550°C is the greatest,with an increase of about 21.8%;the gas yield is reduced,and it is the highest at 550°C,about 17.9%.GC-MS analysis of tar oil showed that under the N₂ atmosphere,the yield of aliphatic hydrocarbons decreased after the addition of char,and the yield of PAHs first decreased and then increased slightly.Phenols and oxygen compound yield increased.Under H₂ atmosphere,the content of PAHs decreased and the PAHs content increased before500°C.After 500°C,the content of PAHs decreased slightly.With the increase of temperature,the content of monocyclic aromatics and phenols also increased.Atomic substance content as a whole showed a decreasing trend with increasing temperature.In order to explore the influence of char on volatiles,the coal tar model compounds were prepared to simplify the secondary reaction factors,and the secondary reactions of volatiles in the char layer were simulated.The coal activated carbon and?-Al₂O₃ carriers were investigated.The pyrolysis behavior was analyzed by using an on-line gas mass spectrometer for pyrolysis gas phase products.The results show that,under N₂ atmosphere,activated carbon mainly promotes the decomposition of light components in tar,and generates small molecule gases such as CO₂ and C₁-C₃ alkane gases and monocyclic aromatic hydrocarbons;it can be seen by comparing the pyrolysis products of?-Al₂O₃ carriers.The pyrolysis products and species obtained by the activated carbon carrier are much richer than the pyrolysis products of the?-Al₂O₃ carrier.The pyrolysis rule under H₂ atmosphere is similar to that of N₂,but overall;more C₁-C₃ alkane gas is obtained under H₂ atmosphere.Finally,the pyrolysis rules of n-propylbenzene and?-naphthylmethylether on different carriers were investigated.It was found that the activated carbon carrier can promote the decomposition under the H₂atmosphere,and the?-Al₂O₃ carrier has no promotion effect.