Study On Catalytic Degradation Of Sulfate Lignin And Resveratrol By Co (salen) Catalytic Paper

Lignin is a complex three-dimensional phenyl-propanoid polyphenol, together with cellulose, hemicellulose for the main skeleton of the plant, lignin as a macromolecule polymer is considered as the second most abundant organic natural compound next to cellulose. However, due to its complex structure and complicated degradation, the research and utilization of lignin were limited. In spite of this, lignin is one of the biomass chemical raw materials on earth, and is used in a wide range of applications for biobased economy due to its large production, renewability, nonhazardness as well as different functional groups. The attention to lignin is also increasing in the field of chemical industry, energy, materials and other fields.In today’s society, with the increase of people’s awareness of environmental protection, laws and regulationst, the development of environmental-friendly, green and recyclable catalyst become one of the research direction in the field of catalysis. The immobilization of catalyst into inorganic fibers becomes the focus of study.In this study, the catalyst paper composed of ceramic fiber and Co(salen) was prepared using a papermaking technique, called Co(salen) catalyst paper. Catalytic performance of the Co(salen) catalyst paper was analyzed by BET, XRD, ICP-AES and the catalyst paper was used as catalyst for oxidation of kraft lignin and lignin model compound (veratryl alcohol). Residul kraft lignins in catalytic processes were characterised by GC-MS, GPC,1H NMR,13C NMR and 2D HSQC NMR to understand the performance of catalyst paper on the structural changes of kraft lignin and lignin model compound. In addition, the utilization of Co(salen) catalyst paper is a new useful exploration in the lignin degradation for the production of high value-added chemicals.Conclusions presented in this study were summarized as follows:Co(salen) powders were homogeneously scattered over a ceramic fiber network to give a catalyst paper and the mixture of Co(salen) powders and ceramic fiber was prepared. The pore diameter of the Co(salen) catalyst paper and Co(salen)-ceramic fiber mixture was 6.21 μm and 13.07 μm by mercury intrusion analysis. The Brunauer-Emmet-Teller(BET) calculated the specific surface areas of Co(salen) catalyst paper and Co(salen)-ceramic fiber mixture was 864 m2·g-- and 601 m2·g-1. The cobalt content in the Co(salen) catalyst paper and Co(salen)-ceramic fiber mixture was 0.76 wt% and 0.51 wt% by ICP-AES.The Co(salen) catalyst paper was used in the degradation of kraft lignin and lignin model compound in comparison with Co(salen)-ceramic fiber mixture and Co(salen) powders. The catalyst paper exhibited an improved effect as compared to the mixture and the Co(salen) powders according to the chemical compositions from kraft lignin by GC-MS and GPC, which is due to the structural effect of an interconnected 3D-network. Under the optimum reaction conditions, the TON of veratryl alcohol catalyzed by Co(salen) catalytic paper, Co(salen)-ceramic fiber mixture and Co(salen) powders were 51,45 and 25. In the catalytic degradation of kraft lignin, the catalyst paper demonstrated itself to be twice as active as the Co(salen) powders with oil yield of 23.27% and a phenolic compound yield of 2.32 mg 2,6-dimethoxyphenol,2.63 mg syringaldehyde, and 3.80 mg vanillin/kg kraft lignin.The content and leaching of Co are tested by ICP-AES. The result showed that the Co content in the Co(salen) catalyst paper and the catalysts have no change during the reaction, which indicate that Co(salen) catalyst paper was stable along with excellent recycling performance.