Synthesis Of The N-O-N/N-S-N Type Cuprous Chelates And Their Catalytic Performance Study For Methanol Oxidation Carbonylation

Cuprous chloride complexes used in oxidative carbonylation of methanol in liquid phase has a history of more than 20 years,but how to achieve intense co-ordination of catalyst among the catalytic efficiency,service-life and corrosive is still a challenging research topic.It is worth noting that the coordinating-atom and the overall structure of the ligand are the decisive factor of catalyst performance,and which have been ignored for many years.Over the years,our laboratory has designed and synthesized a variety of N-N-N type tridentate ligands,and has accumulated a large number of research achievements in the preparation of dimethyl carbonate from methanol liquid phase oxidative carbonylation experiment catalyzed by cuprous chelates.In this paper,we explored the relationship between catalytic behaviour and the coordinating strength.New types of complexes from N-O-N and N-S-N tridentate ligand were synthesized instead of the original N-N-N type ligand.The new cuprous chloride chelates were used in methanol liquid phase oxidative carbonylation,laying a theoretical and practical basis for the development of industrial application-type catalyst.The first chapter is a literature review of dimethyl carbonate(DMC)and its catalysts.The current synthesizing methods of DMC were introduced,and diffirent catalytic mechanisms were analyzed.Finally,the research topic of this thesis is expounded.The second and third chapters are about the synthesis of 2,5-bis(2-pyridyl)-3,4-dihydroxy furan and its derivatives,2,5-bis(2-pyridyl)-3,4-dihydroxy thiophene and its derivatives,as well as their cuprous chloride complexes.Dipyridyl methyl ethers(or thioethers)were firstly synthesized mainly from 2-pyridine methanol,sodium sulfide and2-chloromethylpyridine hydrochloride,then ring-closed reactions were carried out with diethyl oxalate.Finally,a series of ligands were obtained by O-alkylation.The structures of all compounds had been confirmed by various characterization techniques.In the fourth chapter,it was tested in oxidative carbonylation of methanol in liquid phase for the new complexes’catalytic property,which was under simulated industrial conditions.All reactions had been completed in a high-pressure reactor at 120℃and 2.4 MPa in 5 hours,and the catalytic data,such as methanol conversion rate,DMC selectivity,time-space conversion rate,were obtained by gas chromatography.Experiments have found that2,5-bis(2-pyridyl)-3,4-dihydroxy furan hexylated cuprous chloride complex has a good comprehensive catalytic effect.The average time-space conversion rate is 0.903(g.DMC/g.cat.h),The selectivity of DMC is 72.3%,and the corrosion rate is 2.5g/(m~2·h).Compared with the catalytic performance of terpyridine-cuprous chloride complexes,it showed better catalytic activity.Similar complex with thiophen ligand exhibited poor comprehensive catalytic effect.The research results provide an important idea for the design of efficient catalysts for oxidative carbonylation in the future.