Synergetic effect during co-pyrolysis of low-rank coal and polypropylene
The coal reserves in Xinjiang are rich,with a high proportion of low-rank coal.Among them,the coal in Hami region is general-ly characterized by high volatile content,which is suitable for the tar and gas by pyrolysis.However,there are many problems with pyroly-sis tar,such as high content of heavy components,high viscosity and easy to carry dust.Therefore,how to reduce the content of heav-y components in tar and improve the quality of tar is the key to realize high value utilization.Plastics and coal have similar pyrolysis inter-vals but the H/C atoms of plastics is much higher than that of coal.The hydrogen-rich components produced during pyrolysis could pro-mote the primary pyrolysis reaction of coal or inhibit the cross-linking phenomenon during coal pyrolysis.Volatiles interaction exists during co-pyrolysis of coal and plastics,which is closely related to the contact mode of raw materials.The co-pyrolysis of polypropylene(PP)and Naomaohu coal(NMH)were investigated by combing TG,TG-MS and TG-FTIR-GC/MS.TG-MS results show main pyroly-sis temperature range of the two rapid decomposition stages basically coincided,and the formation of·CH3 during PP pyrolysis.When PP layer is placed on top of NMH layer with different mass ratios,the weight loss characteristics and the volatiles evolution of NMH exhibit an obvious difference.The strongest synergy appears on the mass ratio of 8:2 for NMH and PP during the co-pyrolysis process.TG-FTIR-GC/MS experimental results reveal that the synergistic effect of NMH and PP changes the release form of oxygen because the radicals from PP pyrolysis facilitates the cleavage of covalent bonds of NMH,leading to the increase of CO and H2O yields but the decrease of CO2 yield.Compared with the theoretical calculated values,the relative content of alkene and alcohols increases by 30.58％and 16.18％,while those for CO2 and alkanes decreases by 8.89％and 14.43％,respectively.The activation energy of co-pyrolysis calculated by Fly-nne-Walle-Ozawa is 6.8 kJ/mol lower than the theoretical value,confirming that PP is conducive to the release of NMH volatiles.
Naomaohu coal and polypropyleneco-pyrolysissynergetic effectactivation energy
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