The Pyrolysis Of Lignin And Its Model Compound Guaiacol

With the increasing consumption of fossil fuels and the deterioration of environmental problems,the conversion of lignin into biofuels has become an important research direction.Lignin can produce biofuels or chemicals through fast pyrolysis.Our research focuses on lignin and its model compounds.The research purposes are the preparation of high-efficiency catalysts,the improvement of pyrolysis conditions,the exploration of the pyrolysis mechanism and the search for new production processes.We hope to obtain a scheme that can make lignin fast pyrolysis to prepare high-value aromatic compounds and biofuels.Through the analysis of the experimental results,the research contents and results are summarized as follows:(1)The pyrolysis experiment found that the yield of PAH obtained by pyrolysis was the lowest at 550? by using guaiacol as raw material.The effects of catalysts were investigated through pyrolysis catalysis experiments.The maximum yield of monocyclic aromatic compounds was obtained by Ni La/HZ-SH catalysis,including Phenol(23.01%),2-Methylphenol(31.48%),etc.The Ni/La hierarchical catalyst that we prepared shown good thermal stability in the regeneration cycle test,and the relative yield of PAH decreased significantly from 8.10% to 2.68% which obtained after the regeneration test.Based on the experimental data and references to other literatures,the complete conversion mechanism of guaiacol was proposed.(2)Our research wants to explore the performance of lignin in pyrolysis under different temperatures and different catalysts.This part of the experiments investigated the effect of the catalyst Ni La/HZ-SH on the pyrolysis of lignin.The catalyst Ni La/HZSH significantly increased the yield of minor molecular aromatics which obtained from lignin pyrolysis,and some products made a breakthrough.When the pyrolysis temperature is 550?,under the action of the catalyst Ni La/HZ-SH,the highest pyrolysis lignin yield is 9.13%(less than 2%,non-catalyzed).(3)Lignin pretreatment could promote the selectivity of pyrolysis product production.The experiment explored the effect of ethanol hydrothermal pretreatment on the distribution and yield of corncob lignin(RL)pyrolysis products.It can be found from the DTG chart that the main temperature interval of pretreatment lignin pyrolysis is advanced,and the maximum pyrolysis yield is much higher than that of untreated lignin.The yields of minor molecule aromatics in the untreated lignin pyrolysis are less than 2%,which in the pretreatment lignin pyrolysis is 11.35%.Ni La/HZ-SH catalytic help pretreatment lignin gets the 18.49% yield in pyrolysis production.Comparing these three sets of data,we found that the selectivity of pyrolysis products of lignin is improved.Research in this article provided a Ni/La hierarchical HZSM-5 catalyst and successfully combined the hydrothermal pretreatment of ethanol with catalytic pyrolysis,which provides a new method for further improving the product selectivity of lignin pyrolysis oil.