Study On Biomass Pyrolysis Kinetics And Mechanisms

With the development of industrial civilization, the consumption of fossil fuels-oil,natural gas and coal–is accelerating year by year, and thus energy crisis andenvironment problems intensifies. The geopolitical problems happened recent yearsaggravate the energy shortage. Under this circumstance, finding out a suitablealternative energy resource and chemical raw material is crucial to cope with anypossible energy crisis. Biomass as a reliable renewable energy resource seems to be apromising solution.This paper brought about a research on the basic properties and pyrolysis behaviorof18fuel-oriental biomass materials, by the use of TG-FTIR experiments, and someother subsidiary analysis including proximate and ultimate analysis, chemicalcomposition analysis, ICP ion analysis and solid-phase FTIR analysis. Meanwhile anonline quantitative analysis of FTIR analyzer was applied on the gas phase products COand CO₂, CH₄and NH₃,in which the pyrolysis TG curve and the yield of products werecompared under different circumstance, with different particle sizes or heating rates.Further, some regular patterns of biomass pyrolysis were discussed, and a direct solvingmethod, elementary reaction method, based on distributed activation energy method wasput forward.The result of this research indicates that, though the element content, ash content,and combustible matter content have great distinction in different samples, thecomposition and pyrolysis characteristics are quite similar. The comparative analysisreflects that inbounding the set-up of this experiment, parameters such as atmosphere,particle size and heating rate did not distinctively influence reaction rates, butsignificantly changed the yield of gas phase products. In addition, the impact of metalions and organic groups on the pyrolysis process and the possible mechanisms was alsodiscussed.The corn cob sample and the tree root sample were carefully analyzed due to theirspecial pyrolysis behavior. An additional weight loss peak at relatively low temperature（²00℃） was observed in Corn cob sample, and an similar additional peak of tree rootwas found in relatively high temperature （⁵00℃）. FTIR analysis points out that in corn cob, there must be some component with structures similar to hemicellulose, but withlower polymerization degree. And in the root sample, it is considered some uniquemacromolecular components exist which would decompose in a relatively hightemperature forming significant yield of carbon monoxide.On the basis of the experiments, the elementary reaction method assumed that:1)all the biomass materials are constituted with a series of same components, and2) allthe macroscopic characters of biomass have some extent of additivity, which means, forexample, the CO yield of biomass material should be the sum of CO yield of all theelementary reactions. Exploratory research was performed on the yield of carbonmonoxide and methane for verification. Therefore，this elementary reactions method canboth reflect the kinetic behavior of biomass pyrolysis and calculate the total yield ofcertain gas phase products by use of TG curves.