Research On The Influence Of Reaction Atmosphere And Temperature On The Physical And Chemical Properties Of Biomass Semi-coke

Biomass refers to forestry,specially grown crops,trees and plants,as well as organic,agricultural,agro-industrial and household waste.It has the characteristics of renewability,carbon neutrality and rich reserves,and is very promising for research.Its rational application and resource utilization are important steps to solve the energy crisis.The three substances（bio-oil,biochar,and gas）produced by biomass through pyrolysis technology have different degrees of industrial application,which is one of the high-quality means to effectively improve the utilization rate of resources.Biochar as a pyrolysis of the main solid product,with low cost,excellent performance,strong stability and other advantages,it has been applied in various fields.This article from the cellulose and lignin of the two as the biomass of the main component of departure.Study of the pyrolysis temperature and reaction atmosphere on the biomass Char physical and chemical nature of the impact.Then to sawdust as the research object,the study of homologous Bio-Oil on the sawdust pyrolysis biochar physical and chemical nature of the impact.The main research contents are as follows:（1）In the 400 to 700℃ temperature range,with cellulose as the raw material,N₂ or CO₂as the reaction atmosphere for the pyrolysis,the graduate substances Char physical and chemical nature of the impact.The results showed that the CO₂ by suppressing biochar pyrolysis and promotion of the volatiles of the secondary condenser,at 600℃,the following will improve the biochar yield,while reducing the Bio-Oil has aπ-conjugated structure of the organic matter abundance.While CO₂ as the reaction atmosphere to produce biochar in the carbon content will be significantly improved,and the oxygen content is correspondingly reduced.This indicates that the CO₂ atmosphere promotes the pyrolysis process of deoxygenation and dehydrogenation reactions.And in a CO₂ atmosphere under pyrolysis biochar is also more aromatic,thermal stability,energy density and the calorific value is also improved.As the pyrolysis temperature increase and CO₂ atmosphere,the biochar surface oxygen-containing functional groups of evolved significantly affected.（2）Using lignin as the experimental object,pyrolysis was carried out in N₂ and CO₂ at a temperature of 400 to 700℃,respectively,to study the physical and chemical properties of the semi-coke of the substance.The results showed that the CO₂ atmosphere interfered with the pyrolysis process and promoted the formation of bio-oil and biochar by inhibiting the further gasification of volatiles.More monocyclophenols are retained in the bio-oil,and phenols with a polycycle structure are formed through secondary condensation.The CO₂ atmosphere enhances the aromatization process,resulting in carbon-rich biochar with higher value.In Situ infrared characterization shows that CO₂ promotes the removal or transformation of aliphatic functional groups and enhances the carbonization of biochar.（3）Taking poplar sawdust as the research object,first perform rapid pyrolysis at 500℃ to obtain bio-oil,then impregnate it in sawdust,and obtain biomass semi-coke by pyrolysis to study its physical and chemical properties.Studies have shown that the cross-polymerization reaction between the organic matter impregnated in the bio-oil and the organic matter or active volatiles on the biochar improves the yield of the biochar.This led to the formation of additional aliphatic carbon deposits on the surface of the biochar,but these deposits did not improve the thermal stability of the biochar,but instead reduced the activation energy and ignition temperature of the combustion,and improved the combustion performance of the biochar.The carbon content in biochar has also been increased,while the oxygen content has been significantly reduced.This shows that impregnation with bio-oil will increase the degree of deoxygenation and carbonization in the pyrolysis reaction.In addition,the impregnation of bio-oil does not fill the pores on the surface of the biochar,but interacts with the biochar,promoting the formation of mesopores(S>2nm:178.6 m²g^-1 and the corresponding 117.6 m²g^-1),and creates a surface of biochar that lacks carbonyl groups.