Naomaohu Coal And Its Macerals Pyrolysis Behavior Under CO₂ Reforming Of Methane

The macerals in coal comes from different origin and are significant differences in chemical structure and properties,which show different effects on the pyrolysis conversion and product distributions.The integrated coal pyrolysis with CO₂reforming of methane?CP-CMR?has been reported to improve the tar yield.However,the effect of macerals in coal on this integrated process is still unknown.In this study,Naomaohu raw coal?NMH-R?and its macerals-rich coals,including vitrinite-rich coal?NMH-V?,inertinite-rich coal?NMH-I?and exinite-rich coal?NMH-E?were used to investigate the pyrolysis difference.The effect of temperature and different atmosphere including N₂ atmosphere and CO₂ reforming of methane?CRM?atmosphere on the product distribution,especially on the tar yield and composition were investigated.The obtained results can provide experimental evidence and theoretical foundation for the oriented conversion of coal.Under atmospheric pressure,different pyrolysis temperature and different atmosphere can both affect the coal pyrolysis results.As compared to N₂ atmosphere,the tar yield increase under CRM atmosphere.The highest tar yield for the macerals-rich coals show a little difference.With the increase of pyrolysis temperature,the tar yield showed a tendency of increasing first and then decreasing,and the chat yield decreased with the increase of pyrolysis temperature.The highest tar yield for the NMH-V and NMH-R is at 600 ^oC and 650 ^oC,respectively.At 600^oC,for raw coal,pyrolysis tar yield under CRM is 1.27 times higher than that under N₂ atmosphere,but for Exinite-rich coal,pyrolysis tar yield under CRM is only 1.11times higher than that under N₂ atmosphere.The fraction distribution and chemical composition were analyzed and it was found that CP-CRM can increase tar yield but decrease light tar content.Aliphatic hydrocarbons are centered on saturated aliphatic hydrocarbon and oxy-compounds are centered on phenols.CRM increase acid molecules in tars.Isotopic tracer results showed that free radicals produced in CRM process can stabilize the free radicals from coal pyrolysis,and its role is mainly to stabilize benzene-contained compounds in tar rather than aliphatic hydrocarbon.The CRM process had different impact on macerals,intensity and amounts of replacement are different among these coals.