Cesium-phosphorous-silicon mixed oxide (Cs-P-Si oxide), a typical acid–base bifunctional catalyst, efficiently catalyzes propylene carbonate synthesis from CO2 and propylene oxide under supercritical conditions (8-10MPa). This catalyst contains no halogens and requires no additional solvents.A portion of the catalyst was eluted into the product solution during catalysis. It was also found that Cs3PO4, one of the species that may be eluted from the Cs-P-Si oxide, is an effective non-halogen homogeneous catalyst.

A homogenous binary catalyst system, n-Bu4NBr/n-Bu3N, was found to be active for the synthesis of dimethyl carbonate from styrene oxide (SO), methanol, and supercritical CO2. Under the optimized conditions, the dimethyl carbonate yield could reach 84% at SO conversion of 98%. Several parameters were studied, i.e. catalyst precursors, reaction time and temperature, methanol/epoxide feed ratio in moles, and CO2 pressure. The best compromise for the one-pot synthesis was achieved with an equimolar amount of n-Bu4NBr/n-Bu3N. A possible mechanism for the present n-Bu4NBr/n-Bu3N-catalyzed one-pot synthesis of dimethyl carbonate was proposed.

Ruthenium and rhodium phosphine complexes catalyze the hydrosilation of olefins in dense carbon dioxide. The incorporation of polyfluorinated phosphine ligands in the conventional hydrosilation catalysts provides enhanced solubility in dense carbon dioxide resulting in a higher catalytic activity and selectivity; the best result was obtained using RuCl2[P(C6H4-p-CF3)3]3. The reaction is applicable to the synthesis of a fluorous silane coupling agent.

Polyfluoroalkyl phosphonium iodides, Rf3RPI (Rf=C4F9C2H4, C6F13C2H4, C8F17C2H4; R=Me, Rf), catalyzed propylene carbonate synthesis from propylene oxide and carbon dioxide under supercritical CO2 conditions, where propylene carbonate was spontaneously separated out of the supercritical CO2 phase. The Rf3RPI catalyst could be recycled with maintaining a high CO2 pressure and temperature by separating the propylene carbonate from the bottom of the reactor followed by supplying propylene oxide and CO2 to the upper supercritical CO2 phase in which the Rf3RPI remained.

Supercritical carbon dioxide is efficiently converted to dimethyl carbonate (DMC) via the reaction with methanol in the presence of a catalytic amount of dialkyltin oxide or its derivatives. The removal of water is the key to accomplishing the high conversion by shifting the equilibrium to dimethyl carbonate. Dehydration is successfully carried out by circulating the reaction mixture through a dehydrating tube packed with molecular sieve 3A. Under the effective dehydration conditions, the DMC yield is almost linearly dependent on the reaction time, catalyst amount, methanol concentration, and CO2 pressure.