Study On The Copolymerization Of SO₂ And Epoxy Compound Catalyzed By Aminocellulose Supported SalenCr

In recent years,the high value-added utilization of sulfur dioxide?SO₂?has drawn extensive attention.The synthesis of polysulfite by copolymerization of SO₂ and epoxide is one of the research directions.At present,the catalytic system of the copolymerization reaction includes Lewis base?pyridine,quinoline,etc.?,Lewis acid?SnCl₄,SnCl₅,etc.?,Salen metal,and organic zinc?zinc glutarate,etc.?,of which the Salen metal catalyst has attracted the attention of researchers because of high catalytic efficiency,ease of synthesis,insensitivity to moisture,and suitability for a variety of catalytic systems.However,the inability to recycle and reuse is a technical bottleneck in the process of industrialization of the catalyst,and it is possible to break through this bottleneck by loading the homogeneous catalyst through a solid support.Amino-functionalized cellulose?AFC?was used as a carrier to support homogeneous SalenCr?tBu?catalyst?AFC-SalenCr?tBu??for the copolymerization of SO₂ with cyclohexene oxide?CHO?.The effects of different factors on the copolymerization were systematically investigated,and the thermal degradation kinetics of the polysulfite were analyzed.The main contents are as follows:1.Through schiff base reaction between salicylaldehyde with different substituents and ethylenediamine,the SalenCr?tBu?and SalenCr?Cl?catalysts were used for the copolymerization of SO₂ and CHO,respectively.The ¹H NMR analysis of the product showed that the catalyst of SalenCr?tBu?had better catalytic effect than SalenCr?Cl?catalyst.2.The FTIR,XPS and ICP characterization methods were used to prove that the AFC-SalenCr?tBu?catalyst was successfully prepared and used for the copolymerization of SO₂ and CHO.The optimum copolymerization conditions were determined by changing the reaction temperature,the molar ratio of catalyst to CHO and the reaction time,which was 90°C,1:1200,12 h,respectively.Under this reaction condition,the CHO monomer conversion rate was greater than 99%,and the polysulfite selectivity was 88.97%.The sulfite unit content was 62.85%,and the molecular weight was up to 40133 g/mol.AFC-SalenCr?tBu?can be recycled for 3 times without significant loss of catalytic activity.3.The thermal degradation kinetics of copolymer prepared by SalenCr?tBu?and AFC-SalenCr?tBu?catalysts were carried out at different heating rates using thermal gravimetric analyzer.The activation energy of the thermal degradation of the product was estimated using Flynn-Wall-Ozawa?FWO?,Kissinger and Coats-Redfern methods.The Kissinger method was used to calculate activation energy of the copolymer catalyzed by the two catalysts,which was 115.0KJ/mol,94.0KJ/mol,respectively.The fit of both lines was bove 0.99.