A kinetic study of Zn halide/TBAB-catalysed fixation of CO2 with styrene oxide in propylene carbonate

Abstract

Synthesis of styrene carbonate (SC) via the fixation of CO2 with styrene oxide (SO) has been investigated using a combination of zinc bromide (ZnBr2) and tetrabutylammonium halides (TBAX) as acid-base binary homogeneous catalysts. The combination of ZnBr2 and TBAB had a synergistic effect, which led to about 6-fold enhancement in the rate of SC formation as compared to using TBAB alone as a catalyst. Propylene carbonate (PC) was chosen as a green solvent for a comprehensive study of reaction kinetics. The reaction followed a first-order kinetics with respect to SO, CO2, and TBAB, whereas a fractional order was observed for the ZnBr2 when used in combination with the TBAB. Arrhenius and Eyring’s expressions were applied to determine the kinetic and thermodynamic activation parameters, where activation energy (Ea) of 23.3 kJ mol−1 was obtained for the SC formation over the temperature range of 90-120°C. The thermodynamic analysis showed that positive values for enthalpy (ΔH‡ = 18.53 kJ mol−1), Gibbs free energy (ΔG‡ = 79.74 kJ mol−1), whereas a negative entropy (ΔS‡ = –162.88 J mol−1 K−1) was obtained. These thermodynamic parameters suggest that endergonic and kinetically controlled reactions were involved in the formation of SC from SO and CO2.

Photo-Responsive Signatures in a Porous Organic Polymer Enable Visible Light-Driven CO2 Photofixation

“…To gain deeper insight into the mechanistic pathway for the conversion of STE to STC involving CO 2 fixation, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was carried out. Figure g shows a distinct band at 863.70 cm –1 that can be assigned to the C–O frequency in the reactant styrene epoxide . Initially, the epoxide binds with the metal center of the ZnCl 2 cocatalyst, which is reflected in the in situ DRIFT spectra with a C–O frequency of 680.28 cm –1 .…”

“…Figure 6g shows a distinct band at 863.70 cm −1 that can be assigned to the C−O frequency in the reactant styrene epoxide. 64 Initially, the epoxide binds with the metal center of the ZnCl 2 cocatalyst, which is reflected in the in situ DRIFT spectra with a C−O frequency of 680.28 cm −1 . The metalcoordinated epoxide exhibited a much lower stretching frequency (680.28 cm −1 ) compared to the free epoxide (863.70 cm −1 ) due to the weaker metal-coordinated C−O bond.…”

Highly Exposed NH2 Edge on Fragmented g‐C3N4 Framework with Integrated Molybdenum Atoms for Catalytic CO2 Cycloaddition: DFT and Techno‐Economic Assessment

“…It should be noted that without the addition of nucleophilic anions, such as Br − from TBAB (Figure 3e), Mo 2 GCN was unable to selectively produce PC because the opened ring of PO could not close. [ 41 ] Among the halide anions, Br − was reported to have the optimal nucleophilicity and leaving ability, which means Br − is sufficient to maintain the PO's ring opening step and does not hinder the ring from closing. [ 42 ] In a general CO 2 cycloaddition reaction ( Figure ), [Step 1] prior to the ring opening, the epoxide ring should be activated by initiating the coordination bond between electron‐deficient Mo atoms (Lewis acid group) and the O atom (epoxide ring) of PO.…”

“…This was predominantly owing to the substantial differences in the purchase prices of the catalyst materials (Table S9, Supporting Information). Using the bulk price trend extrapolation for each material outlined in Figure 7g,h and the combined price data points obtained from the websites of American, [ 41 ] Chinese, [ 42 ] and Japanese [ 42 ] chemical manufacturers and wholesalers, the total prices of the required amounts of EMImCl and Mo 2 GCN were estimated. Even when accounting for the synthesis costs of Mo 2 GCN, which were assumed to be 5% of the total combined cost of the individual ingredients, the initial price of the catalyst was 893 USD.…”

Chemical Fixation of Carbon Dioxide into Cyclic Carbonates Catalyzed by Porous Materials

“…Epoxide and CO 2 could be efficiently catalyzed into cyclic carbonate by DAT-1 with TBAF, TBACl, TBABr or other co-catalysts. [61] TBABr had the best catalytic effect, and the deionization ability of halide ions was Br À > Cl À > F À . The use of cocatalyst played a crucial role in the ring opening of epoxides and the insertion of CO 2 .…”