Study On Solid-phase Sulfonation Of Polyphenylene Sulfide Nonwoven Fabric And Its Catalytic Performance

At present,most of the catalysts used in various acid-catalyzed reactions are homogeneous catalysts such as concentrated sulfuric acid and chlorosulfonic acid.However,some disadvantages of the catalysts are still significant,such as severe corrosion of the equipment,difficulty in separating from the products,which limit the development of the homogeneous catalysts.Therefore,it is important to develop novel environmental-friendly heterogeneous catalysts.This paper used sulfur trioxide（SO₃）solution as sulfonation agent to sulfonate the polyphenylene sulfide non-woven fabrics（PPS-NWF）under mild conditions to prepare sulfonated polyphenylene sulfide catalytic membrane（SPPS-NWF）.Then it was used as heterogeneous catalyst to prepare biodiesel and cyclohexanone ketal.The research results were as follows:Firstly,PPS-NWF was sulfonated by SO₃solution.The results of XPS and FT-IR indicated that the sulfonation reaction occurred successfully.X-ray photoelectron spectrometer proved that each repeated unit of PPS on the PPS fiber surface was almost attached to one sulfonic acid group.The obtained IEC of SPPS-NWF was between 0.2 and 1.8 mmol/g,while the surface IEC reach to a high value of 5.1 mmol/g.The IEC of SPPS-NWF increased with SO₃concentration and hardly changed with reaction time.As IEC increased,PPS-NWF became rougher,the specific surface area of the SPPS-NWF increased by two orders of magnitude as well as raw fabrics while pore size and the mechanical properties of the SPPS-NWF decreased.In addition,the prepared SPPS-NWF showed good thermal stability that the weight loss of sulfonic groups started at 284.5oC.Secondly,SPPS-NWF was used for the esterification reaction of oleic acid and methanol in the batch and flow-through mode.The results showed that in the batch mode,the conversion rate reach to 97.4%when the temperature was 65oC,the reaction time was 5 h,the amount of catalyst was 0.5 mmol/g（acid）,and the acid/alcohol mass ratio was 1:1.In the flow-through mode,it was found that the conversion reached a maximum of 98.0%under the conditions of the reaction temperature at 65oC,the residence time of 2104 s and the methanol/oleic acid mass ratio of 1:3.Moreover,SPPS-NWF showed good catalytic stability,exhibiting the conversion kept above 95%in the continuous esterification reaction for 50 h in a flow-through mode.Lastly,SPPS-NWF was used to catalyze the condensation reaction of cyclohexanone with glycerol in the batch and flow-through mode.The results showed that in the batch mode,the conversion reached to 97.1%under the conditions of the reaction temperature at 120oC,the molar ratio of glycerol/cyclohexanone of 1:1,the amount of cyclohexane of 7.1 m L,the reaction time of 45 min,and the amount of catalyst of 7.9 wt.%.In the flow-through mode,the cyclohexanone glycerol ketal conversion reached a maximum of 96.3%when the reaction temperature was 120oC,the molar ratio of glycerol/cyclohexanone was 1.4:1,and the residence time was1577.7 s.The SPPS-NWF showed great stability similarly in the condensation reaction that the conversion kept above 93%in the continuous condensation reaction for 20 h in a flow-through mode.The above results show that the synthesis process of SPPS-NWF is simple and effective,is green and environment-friendly.SPPS-NWF has excellent catalytic performance and good application prospect.