Synthesis Of Acetylenic Acids And Acetylenic Esters From Carbon Dioxide Catalyzed By Ag/M-CeO₂

CO₂ is the main green house gas which causes global warming.It is also a nontoxic,non-flammable,abundant,inexpensive and renewable carbon resource.the transformation of CO₂ into value-added fine chemicals through chemical methods has been a strategical research subject for achieving harmonious ecological environment and socio-economic development.Synthesis of carboxylic acids and esters using CO₂ as the carboxylative reagent has become major topic with regard to the activation and catalytic conversion.In this project,mesoporous Ce O₂ with superior catalytic performance was selected as support and nano-Ag with different amounts was loaded as a new catalytic system to study its catalytic activity for carboxylation of terminal alkynes with CO₂ and carboxylation coupling of terminal alkynes,CO₂ and active chloride compounds.The main contents and conclusions include:KIT-6 mesoporos molecular was used as hard template to synthesize the mesoporous Ce O₂.Ag nanoparticles were successfully supported over the oedered mesoporous Ce O₂ to yield Ag/M-Ce O₂.The Ag/M-Ce O₂ were characterized by the means of BET,XRD,Raman,XPS,TEM,CO₂-TPD etc.The synthesized mesoporous Ce O₂?M-Ce O₂?has large specific surface area and regular ordered pore channels.Ag/M-Ce O₂ catalysts with different loadings still have regular ordered pore channels and large surface area.At the same time,silver nanoparticles are uniformly dispersed,and oxygen vacancies increase before loading.Among them,Ag?3.12%?/M-Ce O₂ is highly effective and selective catalytic system for the carboxylative coupling of a series of terminal alkynes,CO₂ and active chloride compounds.Under the optimum reaction conditions,the yield is 91%.We investigated the effect of different dosage of catalyst,alkali type,reaction time,reaction temperature and solvent on the reaction.The catalytic system has good applicability to some alkynes with different substituents and other active chlorides.At the same time,after five consecutive reuses,the activity of the catalyst didn't decrease significantly indicating its good reusability.It is further found that Ag?3.12%?/M-Ce O₂ catalysts exhibits high efficiency for the carboxylation with yield of 93%under the optimum reaction conditions.Catalytic reaction system has a wide range of substrate applicability for carboxylation of some terminal alkynes containing different functional groups.