The Construction And Performance Study Of Polyethersulfone-based Membrane Reactor For The Utilization Of Cellulosic Biomass

With the depletion of fossil fuel resources,the conversion of renewable cellulose biomass resources to biofuels?biodiesel and bioethanol,etc.?and high value-added chemical products have become the focus of international research.Heterogeneous catalysis has become the most promising technology for cellulose conversion with the advantages of environmental protection,no secondary separation of the product and recyclability.However,under the influence of diffusion control,the catalytic efficiency of solid catalyst for cellulose conversion in most heterogeneous catalysis reaction is low.Therefore,combining with other technologies for rapid and efficient degradation of cellulose by solid catalysts has become the key to the effective conversion of cellulose biomass resources.In this study,a catalytic membrane reactor was prepared by combing polyethersulfone?PES?with solid catalyst,and used for cellulose conversion with high efficiency.The membrane technology and catalytic reaction were coupled in the same process to enhance the catalytic efficiency of cellulose conversion.The mian research contents and results are as follows:1. Preparation of highly dispersed sulfonated GO and its degradation of cellulose:the high dispersion of GO-SO₃H and the effective degradation of cellulose were achieved by introducing the solvent N,N-dimethylacetamide?DMAc?into the GO-SO₃H aqueous solution,which can make cellulose soluble and have high electron number.When the volume ratio of H₂O₂/DMAc is 1:10,the GO-SO₃H dispersion system has the best hydrolysis efficiency on cellulose.When the crystalline cellulose was hydrolyzed by the highest GO-SO₃H dispersion,the yield of reducing sugar and glucose were 52.4%and 45.1%,respectively,and the selectivity of glucose was86.1%.Moreover,when the amorphous cellulose was hydrolyzed under the same reaction conditions,the yield of reducing sugar and glucose reached 78.3%and 69.7%,respectively.In the same time,the selectivity of glucose was 89.0%.2. Preparation of GO?SO₃H?/PES catalytic membrane with direct catalytic channels and its efficient degradation of cellulose:highly dispersed GO-SO₃H catalyst was immobilized in PES membrane by blending method to prepare a contact catalytic membrane reactor GO?SO₃H?/PES?GPMMMs?.By regulating membrane forming parameters and process,GO-SO₃H was enriched on the pore surface of the membrane after pre-segregation and segregation process.GPMMMs were used to hydrolyze cellulose in a forced-flow mode to achieve rapid,efficient and continuous degradation of cellulose.When the mass ratio of catalyst in membrane to cellulose is 1/5 and the reaction temperature is 150?,the maximum hydrolysis efficiency of GPMMM-6 on cellulose under dynamic conditions was 98.2%and the maximum glucose yield was92.0%.3. Preparation of m GO-SO₃H-PDA/PES catalytic membrane and its separation and catalytic properties of cellulose:the composite catalytic membrane reactor m GO?SO₃H?-PDA/PES was prepared by the method of“suction filtration-polymerization”.The m GO-SO₃H-PDA/PES catalytic membrane could realize the hydrolysis of cellulose and synchronous separation of sugar production,avoiding the further degradation of sugar products in circular surface hydrolysis of cellulose.Under the flow velocity of 6.8 m L/min,the yield of TRS in separated hydrolysate was 93.2%,the glucose yield was 85.5%.4. Preparation of[Fe O₄]/PES catalytic membrane and study on its oxidative degradation performance of cellulose:the isolated iron Fenton catalyst[Fe O₄]was immobilized in PES membrane by blending method to obtain a contact catalytic membrane reactor?[Fe O₄]/PES?.Fenton reaction was promoted by forced flow mode,and the direct conversion of cellulose to reducing sugar was realized in dynamic Fenton reaction.When the p H of the solution was 6,the amount of H₂O₂ added was196 m M,the reducing sugar yield reached 27.8%after 0.5 h of reaction.