Effect Of Two-stage Pretreatment By Acid-washing And Torrefaction On Pyrolysis Characteristics Of Corn Stalk

As a renewable and clean energy,Biomass have drawn the attention of more and more countrie.Pyrolysis is an important biomass thermal conversion technology.Using this technology,biomass can be converted into oil,gas,coke.However,due to the high oxygen content and the presence of AAEMs,pyrolysis oil has high moisture content,high oxygen content,strong acidity,viscosity,poor stability and other issues.Therefore,it is necessary to take appropriate pretreatment method to reduce the oxygen content of the biomass and eliminate the effects of AAEMs.Torrefaction and acid-washing are both pre-treatment methods that can enhance the quality of biomass.Torrefaction pretreatment can remove oxygen from biomass,and acid-washing pretreatment can effectively remove alkali and alkaline earth metals(AAEMs).In this paper,a two-stage pretreatment method that contains torrefaction and acid-washing was proposed and the coupling effect on the pyrolysis characteristics of corn stalks was studied.Firstly,the corn stalks were washed with deionized water,the water phase of pyrolysis oil,5% acetic acid.ICP-MS analysis showed that water-washing and acid-washing had a good effect on AAEMs,and the acid-washing effect was better than that of washing.Secondly,after the two-stage pretreatment,the corn stalk samples were torrefacted at different temperatures.The yield indicates that the decrease in the torrefaction solid product of the sample after water-washing and acid-washing is slower than the original corn sample.Thirdly,the evolution of functional groups and pyrolysis kinetics of corn stalk were investigated by Fourier transform infrared and thermogravimetric analysis.The micro-chemical processes in the two-stage pretreatment of biomass were revealed.It provides a reference to appropriate two-stage pretreatment conditions.Finally,the corn stalk pyrolysis experimentsthe was done at 550℃.Two-stage pretreatment significantly changed the chemical composition of pyrolysis oil,mainly promote the increase in carbohydrate content,while phenols,acids,furan,ketone content are reduced.The levoglucan in carbohydrates is an important platform compounds.