Study On Pyrolysis Characteristics Of Microalgae And Oil Shale

With the continuous development of economy and urbanization,the rapid growth of energy consumption has brought about serious energy crisis and environmental problems.As a third-generation biomass energy to alleviate the depletion of global fossil fuel reserves,microalgae has received more and more attention in its research and development.As an unconventional oil and gas resource,oil shale is rich in reserves and is an energy resource with great development potential.It has also received increasing attention.In order to achieve more efficient resource utilization and obtain higher quality products,separate pyrolysis studies are moving towards co-pyrolysis and catalytic pyrolysis.Based on the current situation of resource utilization of microalgae and oil shale at home and abroad,this paper focused on the research of liquid pyrolysis by co-pyrolysis and catalytic pyrolysis of microalgae and oil shale,and provides ideas and reference for its comprehensive development of resources.In this paper,a variety of experimental techniques and methods were used to study the reaction characteristics and product precipitation rules of microalgae and oil shale pyrolysis process,as follows:（1）The pyrolysis characteristics of microalgae,oil shale and their mixed samples were studied by thermal synthesis analyzer,and the synergistic effects that may exist during the reaction were analyzed.The pyrolysis weight loss of microalgae and oil shale can be divided into dry dewatering section,pyrolysis devolatilization section and carbonization section,and there was a weight loss main peak.As the mass fraction of the blended oil shale increased from30%to 70%,the TG curve of the mixed sample moved to the right high temperature range,the initial temperature increased from 276.5℃ to 280.0℃,and the termination temperature increased from 386.9℃ to 503.3℃.When the temperature was about 100℃ to 310℃,the mixture TG deviation valueΔW was positive,indicating that microalgae and oil shale had mutual inhibition in the lower temperature range.At high temperatures,ΔW was negative,which showed mutual promotion.（2）The generated gas phase product was detected by Fourier transform infrared spectroscopy.Co-pyrolysis promoted the formation of C-H（hydrocarbons）,while reduced the formation of C=O（acids,esters,ketones and aldehydes）,C-O（alcohols,phenols and ethers）,NH₃ and HCN.Catalysts HZSM-5 and CaO promoted the conversion of phenols,carbonyls,ethers and oxygen-containing heterocycles to hydrocarbons,CO and CO₂ by breaking bonds,recombination and aromatization reactions.（3）The distribution and relative content of pyrolysis products of microalgae,oil shale and their mixed samples were studied by rapid pyrolysis-gas chromatography-mass spectrometry.For the catalytic co-pyrolysis of microalgae and oil shale,with the increase of CaO ratio,the formation of aliphatic hydrocarbons generally showed an upward trend,from 9.57%to 17.48%,while the relative content of aromatic hydrocarbons increased first and then decreased.When the mass ratio of CaO to HZSM-5 was 1:3,the aromatic content reaches a maximum value,which was 2.09%higher than that of single HZSM-5.（4）The catalytic co-pyrolysis kinetics model of microalgae and oil shale was established by equal conversion rate FWO and Friedman method.As the oil shale blending ratio increased,the average activation energy of the mixture decreased,from 278.84 kJ/mol to 192.53 kJ/mol（from 265.51 kJ/mol to 189.63 kJ/mol）.When the CaO/HZSM-5 ratio was 3:1,the average activation energy reached a minimum of 257.29 kJ/mol（269.62 kJ/mol）.In summary,catalytic co-pyrolysis comprehensively utilized microalgae and oil shale,which improved the relative yield of product hydrocarbons and enhanced the energy value of pyrolysis oil,making it possible to replace fossil fuels for application prospects.