Synthesis Of New Bismuth Catalyst And Investigation Of Catalytic Behavior For Cycloaddition Of Carbon Dioxide And Epoxides

Carbon dioxide is one kind of common greenhouse gas. The existence of themcaused global warming, the rise of sea level, land desertification and so on. Carbondioxide is used as the broadest and cheapest carbon resources mainly due to itsnontoxic, stable, easy to transfer and process. It is a new type of green energy.Preparation of chemical products to fix carbon dioxide is a hot research topic intoday’s society. The cycloaddition of carbon dioxide and epoxides is environmentallyprocess. Design and synthesis of efficient catalyst is the focus in the research.In this paper, two kinds of bismuth compounds were designed, the structure wascharacterized by1H NMR、UV-vis. At the same time the catalytic behaviors incycloaddition of carbon dioxide and epoxides was also discussed. A variety ofconditions such as reaction temperature, time, pressure, the ratio of co-catalyst tocatalyst were studied. The products were tested by1H NMR and GPC to judge theyield and the selectivity.The first type of catalyst was bismuth porphyrin catalyst system. They showed highcatalytic activity in cycloaddition of carbon dioxide and epoxides. As therepresentative of iodobismuth tetraphenylporphyrin, a variety of conditions such asreaction temperature, time, pressure, the ratio of co-catalyst to catalyst and axialgroup were studied for the reaction. The optimal condition was at140C,5h,5MPawith1equiv of cocatalyst. The yield was95%at that condition. The electron donatinggroup introducing to the catalyst system will improve the catalytic activity;withdrawing group will lead to a decline. IR and1H NMR showed all the productswere propylene carbonate with high selectivity without polycarbonate and polyether.The second type of catalyst was bridge bisphenol bismuth catalyst system whichcould catalyze the alternating copolymerization of carbon dioxide and styrene oxide.The experiments showed that the change of cocatalyst, temperature, pressure and timewould iMPact on the polymerization reaction. The optimal condition was cat: SO:cocat=1:1000:1、T=140℃、P=5MPa、Time=5h. The number average molecularweight up to17020of the polycarbonate was obtained.1H NMR showed all theproducts were alternating polycarbonate without propylene carbonate and polyether.As most catalysis reactions are carried out in two phases, in which the transferresistance is much higher, along with the difficulty of seperating of the unreactedresidue, by-product and the catalysts, the organic solvent is necessary for thesereactions. In order to find new environmentally green solvents, the solubilities of1,2-haxenediester and the derivatives in supercritical carbon dioxide were determined atdifferent conditions of pressures (8.8-18.8MPa) and temperatures (313K,333K, and353K). The modified compounds showed better solubility than the unmodifiedcounterparts in supercritical CO2and the solubilities increases with increasing pressure but decreases with increasing temperature. Besides, the experimentalsolubility data for those compounds were correlated with the Bartle model and theChrastil model and showed good agreement between the correlated results and theexperimental data. Furthermore, the partial molar volumes of those compounds wereestimated following the theory developed by Kumar and Johnston.