Integrated Coal Pyrolysis With Steam Reforming Of Propane To Improve Tar Yield

In this paper,commercial Ni/Al₂O₃ was used as the reforming catalyst,and Yulin coal?YL?is used as the coal sample.Integrated coal pyrolysis with steam reforming of propane?CP-SRP?was created to increase the tar yield and research tar formation mechanism during the CP-SRP process.The coal pyrolysis experiment uses atmospheric pressure fixed-bed reactor device,and different pyrolysis is conducted through different atmospheres.The results showed that the tar yield of all coal pyrolysis processes increased with temperature and then decreased under different atmospheres,and reached a maximum at 600 ^oC.The introduction of reforming atmosphere was beneficial to the increase of tar yield.The tar yield increase was the most obvious in the SRP process,and the maximum tar yields were 1.17,1.14,and 1.11 times that coal pyrolysis under N₂ atmosphere?CP-N₂?,steam reforming of methane?CP-SRM?,and steam reforming of a large amount of methane mixed with a small amount of propane?CP-SRMP?processes,respectively.At the same time,the process parameters of the CP-SRP process were optimized,and the effects of water-carbon ratio S/C?the ratio of water molecules to low-carbon alkane carbon atoms?and propane flow on tar and char yields were investigated.The results show that tar yield firstly increased and then decreased with increasing S/C,and the yield of char continually decreases.Increasing propane flow can increase tar yield,but decrease char yield.The tar was analyzed by simulating distillation,nuclear magnetic resonance(¹H-NMR and¹³C-NMR),gas chromatography-mass spectrometry?GC/MS?.The results show that the increase of pyrolysis temperature can increase the light oil content in the tar of CP-SRP process,increasing the propane flow can increase the light oil and anthracene oil content in the tar,and the introduction of reforming atmosphere has little effect on tar fraction.The ¹H-NMR and¹³C-NMR results show that the introduction of reforming atmosphere can increase the aromatic hydrogen and aromatic side chain carbon content in tar,indicating that the free radicals generated during the reforming process can combine with coal pyrolysis free radicals and inhibit the condensation and polycondensation process.At the same time,the tar was analyzed by GC and GC/MS.The integrated process increased the content of benzenes,naphthalenes,phenols,aliphatics and PAHs components in the tar,but the benzenes content in the tar decreased during the CP-SRP process.The components detected in tars from CP-N₂,CP-SRMP,CP-SRM and CP-SRP account for 47.51%,53.71%,52.67%and 55.65%,respectively.Finally,C₃D₈?deuterated propane?and D₂O?heavy water?were used as tracers to study the tar formation mechanism in the CP-SRP process.D-NMR of tar and GC/MS analysis of naphthalene,anthracene,1-methyl-naphthalene,phenol and p-cresol reveal that deuterium was present in the tar in both aromatic ring and aliphatic chain.These indicate that both C₃D₈ and D₂O participate in the formation of tar and radicals like?H and?CH₃ produced by the reforming reaction combined with coal pyrolysis free radicals to inhibit polycondensation,thereby increase the tar yield.