Effects Of Pretreatment On Pyrolysis Characteristics Of Loofah Sponge

Thermal conversion technology,known as pyrolysis,has emerged as a promising approach for the high-value utilization of biomass by converting it into clean fuels and chemical products.Due to the highly complex biochemical composition and physical structure of biomass,pyrolysis products exhibit a wide range of complex and variable components.Pretreatment of raw materials can not only significantly change the composition of biomass,but also improve the heat and mass transfer characteristics of biomass.The pretreatment of feedstock prior to pyrolysis is an effective means of investigating the thermal characteristics of biomass.This process not only significantly alters the composition of the biomass,but also improves its characteristics of heat and mass transfer.Loofah sponge is a special biomass material with well-developed pore structure and abundant cellulose and hemicellulose,which has great potential in the pyrolysis for furan compounds.The main components of loofah sponge are cellulose and hemicellulose,making it a high-quality feedstock for producing furan compounds via pyrolysis.This paper investigated the effect of pre-treatment on the pyrolysis characteristics of loofah sponge by using loofah sponge as raw material.At the same time,this paper proposed a high-value utilization method for the co-production of furan compounds and supercapacitor materials by pyrolyzing NH4HSO4-loaded loofah sponge.1.The Effect of Water washing/alkali washing pretreatment on the pyrolysis characteristics of loofah spongeLoofah sponge was washed by deionized water and dilute alkali solution,and biomass pyrolysis experiments were carried out by thermogravimetric-Fourier transform infrared spectrometer and pyrolysis-gas chromatography/mass spectrometry(Py-GC/MS).The effects of pretreatment methods on the composition,pyrolysis characteristics and pyrolysis product distribution of loofah sponge were systematically investigated.Both pretreatments can significantly reduce the content of ash and extract in loofah sponge,and increase the content of cellulose,thus significantly affecting the pyrolysis characteristics of loofah sponge.After water washing and alkali washing pretreatment,the thermogravimetric curve of loofah sponge moved to the high temperature zone,and the activation energy decreased.Based on Py-GC/MS experiments,washing pretreatment significantly changed the pyrolysis product distribution of loofah sponge.Washing pretreatment helps to increase the relative peak area of acids and ketones in pyrolysis products,while alkali washing pretreatment helps to increase the relative peak area of ketones in pyrolysis products.2.Enhancing pyrolysis NH4HSO4-loaded loofah sponge for the co-production of furan compounds and supercapacitor materialsTo realize the high-value utilization of the whole components of loofah sponge,a new method for the preparation of furan compounds and activated carbon by pyrolysis of salt-loaded loofah sponge was proposed.A series of loofah sponge samples loaded with NH4HSO4,(NH4)2SO4,NaHSO4 and(NH4)2CO3 were prepared.Based on a small pyrolysis reaction device,the effects of pyrolysis temperature,salt type and loading amount on the yield of furan compounds were systematically investigated.The results showed that NH4HSO4 was beneficial to the formation of furan compounds.When the ratio of NH4HSO4/loofah sponge was 1:1 and the pyrolysis temperature was 350℃,the total yield of furan compounds was the highest,reaching 3.27 wt%.The pyrolytic carbon obtained under this conditions can be directly activated at high temperature to prepare activated carbon with good electrochemical performance.When the current density is 1 A·g-1,its specific capacitance can reach 212.1 F·g-1,which is a good supercapacitor material.