Experimental Study And Mechanism Analysis Of Catalytic Pyrolysis Of Corn Stalk To Produce Hydrogen-Rich Gas

As a major agricultural country,China has a huge annual output of agricultural waste.Among them,the corn stalks are the secondary products in the process of corn production and processing.They have been treated as waste for a long time,and large-scale abandon or burning has caused serious social and environment problems.It is an effective way to deal with the problems of the environment and energy to develop the way of using the corn stalks and recover the energy from them.The main research content of this subject is to carry out the basic research on the pyrolysis of corn stalk in a tubular furnace.In order to obtain the optimal conditions for the pyrolysis of corn stalk with hydrogen-rich gas,this study first investigated the effect of temperature on the pyrolysis of corn straw,and then tried to use a catalyst to promote the conversion of intermediate products and the generation of high-value gas.Exploring the migration and transformation laws of substances based on the properties of gas-phase,solid-phase,and liquid-phase products,providing a theoretical basis for the resource utilization pathway of producing hydrogen rich gas from biomass.The research results are as follows:（1）Increasing the pyrolysis temperature can significantly improve the gas yield,and the H₂ yield in the gas component increases from 1.2 mL/g at 400℃to 54.1 mL/g at 800℃,and its proportion in the total pyrolysis gas also increases from 0.9%to 22.3%;However,further increasing the pyrolysis temperature will promote the conversion reaction of hydrogen to other gases,which will reduce the production of H₂ to 32.3 mL/g,accounting for 14.3%of the total pyrolysis gas.The relative content of phenols in the pyrolysis oil at 800℃is relatively low,while the relative content of aromatic hydrocarbons increases,resulting in the release of H₂ and CO,which corresponds to the increase of H₂ in the pyrolysis gas products.With the increase of pyrolysis temperature,the surface morphology of pyrolysis char is significantly improved.（2）Adding catalyst can change the process of pyrolysis reaction and affect the yield of pyrolysis reaction products.The best effect is achieved in the experimental group of 10%Ni/CaO＿sg catalyst.The mass ratio of pyrolysis gas increased from 27.8%to 46.5%.The yield of H₂ in the gas component increased from 54.1 mL/g to 142.0 mL/g,and the proportion of H₂ also increased from 22.3%to 32.1%.Under the catalysis of calcium oxide main agent,the disordered pyrolysis reaction of raw materials is more complete,and the yield of pyrolytic char is reduced.Then under the catalysis of 10%Ni/CaO＿sg,the heavy aromatics in the pyrolysis oil are cracked into lighter phenols.The content of alkanes and olefins is increased.All the above reactions promote the increase of the yield of pyrolysis gas and the increase of hydrogen components.SEM images showed that hydrocarbon decomposition or reforming may occur on the surface and inside of straw after adding catalyst,which is beneficial to the pyrolysis reaction.（3）10%Ni/CaO＿sg was modified to further improve the activity of nickel-based catalyst.The best effect was achieved in the experimental group of Ni₃Fe-CaO＿sg catalyst,and the mass ratio of pyrolysis gas increased from 46.5%to 50.4%.The yield of H₂ in the gas component increased from 142.0mL/g to 183.2 mL/g,and the proportion of H₂ also increased from 32.1%to 37.8%.The modified catalyst further promoted the decomposition of organic matter in the pyrolysis oil and was conducive to the generation of pyrolysis gas.