Study On Pyrolysis Of Phyllostachys Pubescens And Effect Of Pretreatments

Because of the depletion of fossil fuels and environmental pollution problem caused by fossil fuel usage, the exploitation and utilization of bioenergy have been paid more and more attention to during recent years. Bamboo is an ideal renewable resource as one of the most important forest resources in China with wide distribution and large amount. In this article, pyrolysis behavior of Phyllostachys pubescens in both TG and a home-made stainless steel tube fluidized reactor was studied. Water and dilute sulfuric acid leaching were taken as pretreatment before pyrolysis. Effects of leaching on feedstock properties and pyrolysis features were clarified. Results here will contribute to the understanding the disciplines of pyrolysis, also provide guide for product processing design and high value-added product development.First, pyrolysis of Phyllostachys pubescens materials were investigated by TG at lower (5-50 K/min) and higher (100-200 K/min) heating rates respectively in the temperature range of 313-773 K and N2 atmosphere. Both model-fitting method and model-free method were used to calculate the weight loss kinetics. Pyrolysis at different conditions was discussed based on comparison and analysis of the kinetics results combined with existed pyrolysis mechanism. Results from the kinetic model fit experimental data pretty well and also can reflect real reaction process.After kinetic study, the pyrolysis of Phyllostachys pubescens was carried out in a home-made tube fluidized reactor. Liquid products were collected then analyzed by GC/MS and GC. Effects of heating rates and final reaction temperatures on pyrolysis products yields (solid, liquid and gas) and concentrations of furfural, phenol and guaiacol in liquid product were studied. Probable pyrolysis reactions leading to phenolic compounds were discussed. It’s concluded that at lower heating rate or lower final reaction temperature, semi-cellulose and cellulose decomposite before lignin. The primary light organic molecule compounds undergo further reactions producing phenols. Decomposition of lignin is promoted when heating rate or final reaction temperature becomes higher, giving birth to most phenolic compounds in liquid product, and secondary reactions of semi-cellulose and cellulose products is depressed.The original feedstock was pretreated by water and dilute sulfuric acid leaching under different leaching time and acid concentrations before pyrolysis. Both original and pretreated sample were pyrolyzed in both TG and tube furnace reactor under different pyrolysis conditions (heating rates and final reaction temperatures). Weight loss kinetics and pyrolysis products of original and pretreated samples were analyzed. Influences of pretreatment on pyrolysis characters were deeply investigated. Effect of water and dilute sulfuric acid leaching on feedstock properties include:(1) Removal of metal ions. Pretreatment can sharply remove metal ions in feedstock. Reductions of ash content by water leaching and dilute sulfuric acid leaching are almost the same. (2) Change of polymer structures. Acid leaching will break polymer physical structures. (3) Addition of slight water content by water leaching and acidic ions by acid leaching. This will influence distribution of pyrolysis products. (4) Changes of main chemical component contents. From the perspective of pyrolysis kinetics, the most important factor of water and acid leaching is metal ion removal, which makes weight loss reactions occur easier. From the perspective of product formation, results show that pretreatments have changed pathways of product formation and increased evidently furfural concentration in liquid product. This result provides some prospects on production of furan and its derivatives.