Upgrading The Properties Of Bamboo And Its Pyrolysis Products Via Torrefaction Pretreatment At Different Atmospheres

Bamboo is a commercial crop in the mountainous area of China,with a wide cultivation area covering 540 million hectares.(1)Torrefaction pretreatment can effectively reduce the moisture content and O/C ratio biomass feedstock,increase energy density,grindability and hydrophobicity.However,the oxygen element migration path in the torrefaction pretreatment process is not clear,so the program temperature controlled tube furnace,TG-FTIR,PY-GCMS and other to begun the bamboo torrefaction experiment,expounded the oxygen removal pathway.The results show that with the increase of torrefaction temperature,the carbon content of solid products increase from 46.12%to 61.23%,the oxygen content decrease significantly from 47.47%to 33.93%,the energy density of solid products after torrefaction was significantly improved;the torrefaction liquid products were mainly composed of organic substances such as acids,phenols,furans and aldehydes,and the contents of acids,phenols and furans were up to 20.34%?22.05%and 31.42%,the content of aldehydes and ketones was less,8.26%and 10.43%,respectively;the torrefaction gas products were mainly H2O,CO2,CH4 and CO,among which the CO2 was the highest,followed by H2O,CH4,CO,and the content of gas product increases with the torrefaction temperature;According to the research and analysis of the three-phase products,the oxygen elements of the bamboo were mainly removed by H2O,CO2,CO and oxygen-containing organic compounds.(2)Pyrolysis as a mature thermochemical conversion technology,is widely used in various fields.However,a large amount of water(40-50%)and oxygenated organic matter(45-50%)in pyrolysis liquid products,which leads to poor quality of pyrolysis products.Torrefaction pretreatment can effectively improve the quality of pyrolysis products,but the mechanism of pyrolysis product formation through torrefaction pretreatment has not clearly.Therefore,the above instruments were used to carry out torrefaction and pyrolysis experiment,and to explore the torrefaction temperatures for the effect of pyrolysis gas,solid and liquid products.The results show that with the increased of torrefaction temperature,the C increase from 46.12%to 61.23%,the O decrease from 47.47%to 31.93%;pyrolysis gas products mainly consist of H2O,CO2,CH4,CO and H2,which CO2 content was the highest,with the deepen of torrefaction,CO2,CO,H2O,CH4 production decreased,H2 production increased;pyrolysis liquid products mainly Acids,phenols,furans and aldehydes.Which the content of acids,phenols and furans,12.69%,34.72%and 29.80%,respectively,and ketones and aldehydes are 9.32%and 11.87%.(3)Ammonia(NH3)is a high nitrogen/hydrogen ratio atmosphere,and the production of nitrogen-rich biomass by ammonia thermochemical conversion to produce nitrogen-containing chemicals has received extensive attention.The above instruments were used to carry out ammonia atmosphere torrefaction and pyrolysis experiments.The result shows the content of nitrogen increased significantly from 0.05%to 7.59%with the torrefaction temperature increased.The solid product functional group mainly consisted of quaternary-N,pyrrole-N and pyridine-N.The pyrolysis gas was mainly composed of H2O and CO2.CH4,CO,NH3,HCN,HCNO and NO,among which CO2 gas production was the highest,the conventional pyrolysis small molecule gas gradually decreases with the increase of pyrolysis temperature,while the trend of N-containing small molecule gas was opposite.The pyrolysis liquid product was mainly composed of acids,phenols,furans,ketones,esters and N-containing compounds.The relative content of N-containing substances in pyrolysis liquid production was up to 19.89%.Based on the above results,it can be seen that ammonia gas as a torrefaction atmosphere can effectively optimize the distribution of biomass nitrogen elements,and then develop a new method for preparing nitrogen-containing chemicals.(4)Based on the shape-selective catalytic ability of zeolite catalyst,the effects of torrefaction temperature,catalyst ratio and pyrolysis temperature on the catalytic pyrolysis products of bamboo under oxygen atmosphere was studied,and preparation process of triphenyl was explored.When the carrier gas atmosphere of the torrefaction pretreatment is 9%O2,the selective yield of BTX in the catalytic pyrolysis product was the highest,and the selective yield of triphenyl was up to 76.32%,which was mainly attributed to the pyrolysis of hemicellulose and cellulose.Oxygen-containing organic matter decarbonylation,decarboxylation and dehydration reaction in the pores of the zeolite catalyst,and phenolic substances produced by pyrolysis of lignin undergo deoxidation and cleavage reaction on the surface of the zeolite catalyst.From the results of PY-GCMS analysis,it can be seen that the preparation of triphenyl has the best benefit after torrefaction at 300? in 9%O2 atmosphere at catalytic ratio of 1:5 and pyrolysis temperature of 850?.It showed that reference for the energy utilization and industrial utilization of bamboo,and the preparation of high quality add-valube production for bamboo.Bamboo was a renewable potential feedstock for the production of bio-oil,bio-gas,and bio-char,using torrefaction pretreatment and subsequent thermochemical conversion technology.