Studies On The Catalytic Conversion Of CO 2 To The Synthesis Of Cyclic Carbonates And N-methylamines

Carbon dioxide is the main component of greenhouse gases,and is also a kind of cheap carbon oxygen resources,therefore the comprehensive utilization of carbon dioxide has received more and more attention.In addition,to deal with the problems of environmental pollution,use CO2 to synthesize valuable chemicals is a significant issue.Furthermore,carbon dioxide activation and chemical conversion is the most important research topics in the field of green chemistry.Biodiesels is useful as clean renewable energy source for the replacement of dwindling petroleum.A main by-product of biodiesels,consequently,the transformation of glycerol to high value-added products has scientific significant and use value.Among the technologies of glycerol conversion,the synthesis of glycerol carbonate from glycerol and CO2 are one of the most attractive routes.In addition,N-methyl or N,N-dimethyl amine compound are the vital part of the N-methylation of amines,carbon dioxide as the methylation carbon source,hydrogen as reduing agent to preparation N-methyl or N,N-dimethyl amine compound had more excellent economical and environmental friendly.This study on carbon dioxide activation,the design of the catalyst and converted to the target product glycerol carbonate and N-methyl and N,N-dimethyl amine compounds has carried on the detailed research,and obtain the following main research results.The conversion of CO2 with glycerol to glycerol carbonate was investigated in the presence of 2-cyanopyridine.It was found that 2-cyanopyridine not only acted as the dehydrating agent to break the thermodynamic limit of the reaction,but also activated the carbonyl bond of CO2 to catalyze the present carbonylation as confirmed by FTIR experimental spectra.Moreover,it closely depends on the stereo-structure of cynaopyridine,that 3-cynaopyridine and 4-cynaopyridine do not have such activating function.The theoretical calculation demonstrated that 2-cyanopyridine could bond CO2 to form a five-ring through the conjugating nitrogen with oxygen atoms of CO2,thus the CO2 was activated and reacted with glycerol to produce glycerol carbonate.With increasing of CO2 pressure the yield of glycerol carbonate increased,and a 18.7%yield was obtained which is one of the best values compared to the results reported up to now.PdGa/TiO2 nanometer catalyst was synthesized,and discuss its in methylation of N-methylaniline with CO2/H2 to N,N-dimethylaniline catalytic activity under the condition.The result indicated that PdGa/TiO2 has better catalytic activity than Pd/TiO2 and the PdGa/TiO2 catalyst exhibited 98%conversion and 94%selectivity under the reaction conditions(180 ?,4 MPa H2,6 MPa CO2,10 h),which are the best results reported up to now for the heterogeneous N-methylation with CO2 as methylation reagent over the supported metal catalysts.The PdGa/TiO2 catalyst was well characterized by using TEM,TPR,XPS,CO-adsorption IR and high-pressure in situ FTIR,It was confirmed that PdGa alloy nanoparticles were formed and highly dispersed on the TiO2 support,and the electron-deficient Pd derived from the interaction with Ga,and improve the ability of activate CO2 and transferred it into formate,which is the key step for the present methylation.