The Application Of Nano Ceria In The Preparing Monomer Of Polyester Via Catalytic Conversion Of Lignin

As an amorphous and three-dimensional network aromatic polymer,lignin is the only renewable aromatic compound on earth as known.Aromatic compunds such as aromatic ketones,aldehydes,acids and so on were used as an important chemical intermediates and platform molecules,which could be obtained from directional catalytic oxidation of lignin.Recently,Terephthalic acid(PTA)regarded as an important resource for industrial production of polybutylene terephthalate(PBT)and poly(ethylene terephthalate)(PET),which was mainly gained by oxidative petroleum cracking of p-xylene.Howerver,with the increasing severity of tension supply and pollution caused by fossil resources,it is urgent to develop a more green and eco-friendly method for production of aromatic compound.Therefore,it is a very practical significance of work to that prepares aromatic acid from lignin.Catalysts are the key to the oreintational tranformation of lignin.The catalyst used in the oxidation of lignin mainly includes organometallic catalyst,noble metal catalyst,acid or base catalyst,metallic oxide,etc.Among them,nano ceria was widely concerned because of its excellent performance.However,the relevant research mainly focused on it as a carrier,and there is no further research and application on it as a catalyst.In this article,the results of experiments showed that the nano cerium with different morphology and structure could be directly used as the catalyst in the process of catalytic oxidation of lignin,and showed that clear structure-activity relationship,aromatic acid methyl ester was prepared form lignin.Firstly,four different morphology and structure of nano ceria were prepared,including the nano rod-shaped,globular,tetrahedron and octahedral.Secondly,the model molecule of lignin was synthesized with the β-O-4 type bond,the relation between the shape of nano ceria and model molecules in the catalytic oxidation was analyzed.The structure-activity relationship of cerium oxide nanoparticles was obtained,namely:the nanorods,nano ball cerium oxide mainly catalytic broke the C-C bond.The nano-octahedral and nano-tetrahedral oxidation ceria preferentially broke the C-O bond.The nano-octahedral cerium has the most selectivty of aromatic compounds.Finally,the catalytic oxidation process of the real lignin was studied by using the octahedral nano oxide as a catalyst.Through the catalytic oxidation of ethanol lignin,the aromatic acid and its methyl esters was prepared from the catalytic oxidation of lignin,and its mechanism of action was discussed.Through the applied research of the nano ceria in the catalytic oxidation of lignin and its model molucule,the reaseach purpose was realized with the derecterly preparing of aromatic acid and its methyl ester.This article provides a new method for the green production of polyester monomer,also provides a new method to solve the problem of bottleneck problem of cotton stalk recycling usage in Xin Jiang.