Low-temperature Catalytic Pyrolysis Of Biomass To Produce 4-vinylphenol

Lignocellulosic biomass is an organic oxygen-containing polymer that can be used to prepare a variety of high value-added chemicals by directed pyrolysis.4-Vinylphenol(4-VP)is an important pharmaceutical and fine chemical chemical.Now it is currently produced primarily through cyclization and precision oxidation with expensive cost.Biomass contains a large number of benzene ring and hydroxyl functional groups,which is an ideal raw material for the preparation of 4-VP.How to improve product yield and selectivity is the focus of current research.In this thesis,a variety of biomass materials were used as raw materials to study the preparation of 4-VP by low temperature catalytic pyrolysis of biomass on a small fixed bed.The aim was to study the effect of the material type,pyrolysis temperature,catalyst type on the distribution of pyrolysis products and the yield of target products.The main conclusions are as follows:Preparation of 4-VP Characteristics by Rapid Pyrolysis of Various Biomass at low temperature was systematically studied,and suitable raw materials and pyrolysis temperatures were obtained.The results show that the main phenolic compounds for rapid pyrolysis of biomass include 4-VP,4-ethylphenol,phenol,4-vinylguaiacol,2-methoxy-4-(1-propenyl)Phenol,4-ethylguaiacol and 4-vinylguaiacol.Woody biomass(poplar,pine)produces more phenol and 4-vinyl guaiacol,while herbal biomass(cane skin,sugar cane,bamboo,corn stover,rice straw)produces more pyrolysis.4-VP,in which the sugar cane skin obtained the highest 4-VP yield.The increase of pyrolysis temperature is beneficial to the formation of the whole phenolic product.The 4-VP yield increases first and then decreases with the increase of temperature,and the excessive temperature makes the selectivity of 4-VP significantly lower.The bagasse was subjected to rapid pyrolysis at low temperature,and the highest 4-VP yield reached the 2.07 wt% at 300 °C.The low temperature pyrolysis characteristics of bagasse under solvent pretreatment and catalysis were studied,and suitable treatment solvents and treatment conditions were obtained.The results show that the pretreatment and catalyzed bagasse with methanol,ethanol,toluene and acetone can greatly increase the yield of 4-VP,and acetone has the best effect.Under the pretreatment and catalysis of acetone,the selectivity of phenolic substances and the yield of 4-VP increased first and then decreased with the increase of pyrolysis temperature,and reached the highest selectivity of phenolic substances at 300?.the highest selectivity of phenolic substances was 42.21% and the maximum yield of 4-VPwas 7.00 wt%,and the yield of 4-VP was increased by 2.4 times compared to the untreated raw material.At low acetone concentration,the yield of 4-VP increased significantly with the increase of acetone concentration.When the acetone concentration was 10%,the yield of 4-VP was 6.33wt%.With the increase of acetone concentration,the yield of 4-VP did not change much and the selectivity was greatly reduced.Therefore,pretreatment of biomass with acetone(concentration 10%)under 300? is the optimal conditions for the preparation of 4-EP and 4-VP by low-temperature catalytic pyrolysis of biomass.