Research On The Pyrolysis Characteristics And Its Products Analysis Of Different Lignin

At present,the utilization rate of industrial lignin is less than 10%,and most of them are used as waste discharge.So this research hope can through to Pinus massoniana belong to softwood and Poplar belong to hardwood with different extraction method to extract different kinds of lignin(acid insoluble lignin,Alkali lignin,Milled wood lignin),and then under the different conditions of three different types of lignin was studied by thermogravimetric analysis and pyrolysis and catalytic pyrolysis,the pyrolysis characteristics of can get different kinds of wood,choose suitable conditions(temperature,catalyst,etc.)can improve the content of single phenolic components in the pyrolysis products of lignin pyrolysis,reduce the separation cost,while exploring the lignin pyrolysis mechanism for using lignin resource basis.Based on the thermogravimetric analysis of different kinds of lignin in masson pine and poplar wood,it was found that the main stage of lignin pyrolysis is the volatile phase,and the apparent activation energy of different kinds of lignin is mainly concentrated in 39-55KJ/mol.The structure and content of the pyrolysis products were analyzed by Py-GC-MS,acid insoluable lignin,alkali lignin and milled wood lignin from Masson pine were used as the raw material for pyrolysis on 5000C.The relative content of total phenols in pyrolysis products of milled wood lignin was 62.3%,and the relative content of Guaiacol was 9.75%,4-methyl-2-methoxy phenol was 8.56%.The relative content of total phenols in pyrolysis products of alkali lignin was 44.86%,the relative content of Guaiacol was 7.76%,acetic acid was 6.31%,and the relative content of total phenols in pyrolysis product of acid insoluble lignin was only 16.25%,the relative content of none phenolic components was more than 5%.The pyrolysis temperature increased from 400 to 700?,while the relative content of total phenols only increased from 59.78%to 62.31%and then increased to 65.72%and then decreased to 45.54%.The relative content of guaiacol and other phenolic compounds increased and then decreased with the increase of temperature,while the relative content of 4-vinyl-2-methoxy phenol decreased with the increase of temperature.The relative content of catechol catechol compounds with increasing pyrolysis temperature increased,the relative content of alkyl phenolic compounds containing methoxy groups are relatively low,also increased slightly increased with temperature.There are also some aldehydes and ketones in the pyrolysis products which contain the basic structure of guaiacol.The pyrolysis of acid insoluable lignin,alkali lignin and milled wood lignin from popular wood was studied under the condition of 500?.The relative content of total phenols in the pyrolysis products of milled wood lignin was 54.28%,and the relative content of 2-methoxy methyl phenol and other compounds were more than 5%.The relative content of total phenols in pyrolysis products of alkali lignin in 48.96%,the relative content of 2-methoxy phenol(5.7%)and some compounds were more than 5%,and the relative content of total phenols in pyrolysis product of acid insoluble lignin was only 37.65%,only the relative content of four kinds of compounds including sulfur dioxide(6.44%)are more than 5%.The structure and content of pyrolysis products from poplar wood were analyzed under different temperature.The relative content of total phenols was increased from 31.44%to 54.28%and then decreased to about 42.85%and then to 25.16%in the process of increasing the pyrolysis temperature from 400 to 700?.The relative content of guaiacol and other phenolic compounds increased and then decreased with the increase of temperature,while the relative content of 2-methoxy-4-vinyl phenol decreased with the increase of temperature.The structure and content of pyrolysis products from industrial alkali lignin were analyzed under different temperature and catalyst.the pyrolysis temperature increased from 400 to 700?,the relative phenolic content increased from 51.86%to 54.37%,then increased to 55.08%,and then increased to 40.86%.Guaiacol(2-methoxyphenol 2-)the relative content of from 400? when the relative content of 6.69%increased to 9.78%on 500? and then decreased to 7.07%on 600? to 5.40%on 700?;the relative content of 4-allyl-2-methoxy phenol from 400? when the relative content of 8.41%down to 5.30%on 500? then decreased to 5.28%on 600? and then decreased to 4.67%on 700?.The six kinds of molecular sieve catalysts ZSM-5(ratio of silica to alumina 25 and 50),HZSM-5(ratio of silica to alumina 25,50 and 130)and Ts-1(aluminum substituted by titanium)were used in the catalytic pyrolysis of milled wood lignin from Masson pine.The results showed that the six kinds of catalysts play a catalytic role in the pyrolysis of milled wood lignin from Masson pine,among which HZSM and Ts-1 catalysts are more effective.But there are also some substances such as 3-methyl phenol,guaiacol,4-ethyl-2-methoxy phenol,3,4-two methoxy toluene on Na zeolite(Si/Al ratio of 25)under the catalysis of relative content were increased,the relative content of 3,4-two methoxy toluene or even increased 40%left right.in Ti02,ZSM-5-25 two molecular sieve catalyst,there were decreased the total phenol content of industrial alkali lignin pyrolysis products,from 54.37%down to 50.13%and 48.94%respectively.Guaiacol is under the effect of-25 content in Na increased significantly,increased from 9.78%to 11.28%,but in the presence of Ti02,the relative content decreased from 9.78%to 9.15%;the relative content of catechol decreased slightly in two under the action of catalyst decreased from 12.42%to 12.11%and 12.19%.