Study On Preparation And Application Of ZnO/attapulgite Composite Catalyst

CO₂ is the main cause of global warming gases,but will it as a resource from a different Angle,non-toxic harmless CO₂ itself,is the most abundant resources of C1 in nature reserves,the CO₂ recycling use,can effectively alleviate the greenhouse effect not only,still can get high value-added industrial waste products,create economic benefits.CO₂ and epoxy compound synthesis of cyclic carbonate is one of the way of the CO₂ recycling use,atom utilization rate can reach 100%,in line with the"atomic"in economics,product cyclic carbonate in the field of medicine,fibres and synthetic plays an important role,the preparation of high catalytic efficiency,high cycle performance is good,low cost,simple synthesis catalyst of cyclic carbonate production is very important.This paper aims to use the special structure of attapulgite to build a composite catalyst for efficient conversion of CO₂,which is mainly divided into the following parts:（1）The methods of synthesizing cyclic carbonate in the literature were reviewed,and the classification and research progress of the catalysts for synthesizing cyclic carbonate from CO₂ and epoxy compounds were reviewed.The physicochemical properties,modification methods and application of attapulgite were systematically introduced,and the design and synthesis ideas of the catalysts were briefly described.（2）Attapulgite as a kind of natural one-dimensional nanomaterials,with a 2:1 type chain structure,continuous tetrahedral and octahedral discrete form attapulgite unique weak alkaline channel structure,the CO₂ adsorption effects of kind of acid gases,the larger specific surface area and smaller size fits as a kind of nano carrier composite with other materials.The metal sites of Mg,Al and Fe on the surface have a certain catalytic effect on the reaction of CO₂ and epoxy compounds,and can form a synergistic catalytic effect with the active component supported.Based on these characteristics of attapulgite,we designed and synthesized ZnO/ATP composite catalyst.Attapulgite acts as the carrier to disperse and control the size of ZnO,and forms synergistic catalysis with ZnO to further improve the catalytic efficiency.The experimental results show that the catalyst has excellent catalytic activity in the reaction of epoxy styrene and CO₂,and has good catalytic effect on a variety of epoxy compounds.After 6 times of catalysis and 5 times of cycle,the catalyst still maintains high catalytic activity,and has good catalytic cycling performance.The catalytic mechanism of the catalyst was speculated and discussed.（3）For heterogeneous catalysts for synthesis of cyclic carbonate often require cocatalyst to guarantee the high selectivity and high conversion rate of the product,cocatalyst usually contain halogen.However,look from the angle of green chemistry,halogen residues can cause pollution to the environment,from the perspective of industrial production,the catalyst promoter and product separation difficulties,each loop have to rejoin the cocatalyst,not conducive to continuous production.Based on the difficulty of recovery of cocatalyst in heterogeneous catalytic system and the excellent physical adsorption of attapulgite,we designed ZnO/ATP-CTAB multifunctional composite catalyst with the concept of semi-homogeneous catalyst,so that the functions of catalyst and cocatalyst can be integrated.At high temperature,CTAB falls off and participates in the reaction.After cooling,the catalyst adsorbs CTAB again to realize the recovery of cocatalyst.The experimental results show that the catalyst has a high catalytic effect on the reaction of CO₂ and epoxy compounds,and keeps the catalytic activity after five cycles,which provides a new research idea for the recovery and fixation of cocatalyst in heterogeneous catalysts.