Study On Pyrolysis Characteristics Of Microalgae And Rice Husk

With the growth of world population and the continuous development of economy and society,people’s demand for consumption,travel and entertainment is increasing,which leads to the increasing global energy consumption.Environmental pollution and energy depletion are two major problems facing human society today.Microalgae,as the third generation biomass to alleviate the depletion of global fossil fuel reserves,has attracted more and more attention in its research and development.Rice husk,as an important agricultural and forestry waste,has a huge output in the world,and its development and utilization has been paid more and more attention.In order to achieve more efficient utilization of resources and obtain higher quality products,the research of single pyrolysis is developing towards mixed pyrolysis and catalytic pyrolysis.Based on the current situation of utilization of microalgae and rice husk resources at home and abroad,this paper focuses on the preparation of liquid fuel by co-pyrolysis and catalytic pyrolysis of microalgae and rice husk,which provides ideas and reference for the comprehensive development of its resources.In this paper,a variety of experimental techniques and methods were used to study the reaction characteristics and product precipitation law of microalgae and rice husk pyrolysis process,as follows:(1)The pyrolysis characteristics of microalgae,rice husk and their mixture were studied by thermogravimetric analyzer(TGA),and the possible synergistic effect in the reaction process was analyzed.The pyrolysis weight loss process of microalgae and rice husk can be divided into drying and dehydration stage,thermal devolatilization stage and carbonization stage.There is a main peak of weightlessness.With the mass fraction of blended rice husk increasing from 30% to 70%,the TG curve of the mixed samples shifted to the high temperature range on the right,the initial temperature increased from 271.9℃ to 282.8℃,and the residual mass fraction increased from 28.62% to 32.87%.When the temperature is between 100℃ and 310℃,the DTG deviation value △W of the mixture is positive,which indicates that microalgae and rice husk have mutual inhibition in the lower temperature range.At high temperature,△W is negative,and microalgae and rice husk show mutual promotion.(2)The distribution and relative content of pyrolysis products of microalgae,rice husk and their mixed samples were studied by pyrolysis-gas chromatography/mass spectrometry(Py-GC/MS).For the mixed catalytic pyrolysis of microalgae and rice husk,the addition of CaO increased the yield of aliphatic hydrocarbons,while the relative content of aromatic hydrocarbons decreased.ZSM-5 catalyst also showed similar effects.Both catalysts reduce the relative content of acids in the mixed pyrolysis products.(3)The kinetic model of mixed catalytic pyrolysis of microalgae and rice husk was established by FWO and KAS methods with equal conversion rate.With the increase of microalgae mixing ratio,the average activation energy of the mixture increased first,then decreased and then increased again.When the ratio of microalgae to rice husk is 1:1,the average activation energy is the lowest among the mixed samples,which is 205.63 kJ/mol(FWO)and 206.58 kJ/mol(KAS),respectively.The activation energy of mixed pyrolysis decreased with the addition of ZSM-5,but increased with CaO.To sum up,the mixed catalytic pyrolysis makes full use of microalgae and rice husk,improves the relative content of hydrocarbon products,improves the energy value of pyrolysis oil,and makes it possible to replace fossil fuels,which has a good application prospect.