Effects of addition mode on Zn–Co double metal cyanide catalyst for synthesis of oligo(propylene‐carbonate) diols

Abstract

Zn-Co double metal cyanide (DMC) complexes are promising catalytic systems for copolymerization of epoxide and CO 2 . In the work reported, Zn-Co DMC catalysts were prepared by parallel-flow dropping, forward dropping and reverse dropping methods, aiming to provide an insight into the effect of addition mode on catalyst structure and catalytic performance. Catalytic properties were evaluated using the copolymerization reaction of propylene oxide (PO) and CO 2 in the presence of chain transfer agent. The results indicated that the factors that affect crystalline state are different for different modes. And excess zinc chloride is the prerequisite for organic ligands to be retained in the catalyst and affect the structure. In addition, a catalyst with flower-like morphology was obtained with the parallel-flow dropping method which provided larger surface area. An appropriate O/Zn value ensured abundant active PO which would suppress the backbiting process by forming consecutive PO units adjacent to CO 2 units. Oligo(propylene-carbonate) diols with average molecular weight of 1020 g mol −1 , CO 2 incorporation of 24.92% and W PC of 5.14 wt% were obtained at 80°C and 2 MPa.

Facile preparation and synergy study of DMC/ZnGA composite catalyst for the synthesis of oligo (propylene‐carbonate) diols

“…The fragment ion peaks at 857, 755, 653 and 551with relative low relative abundance were observed which were attributed to the species of HO‐(PO‐CO 2 ) m ‐H + Na + . And this species was not observed in the oligomers with lower carbonate unit content which verified the value of composite catalyst …”

“…Zn‐Co DMC catalyst was prepared with t‐BuOH as complexing agent and PPG‐3000 as co‐complexing agent by parallel‐flow dropping mode . In a typical synthesis, 2 g K 3 [Co (CN) 6 ] was dissolved in 35 ml deionized water to prepare solution 1.…”

“…The oligo (propylene‐carbonate) polyols with a molecular weight of 1000–2000 g/mol are rarely reported, while it has great application prospect in the synthesis of polyurethane products. Recently, our group synthesize an oligo (propylene‐carbonate) diols with the molecular weight concentrated at 1000 g/mol with Zn‐Co DMC catalyst, while its carbonate content is only 18.3–36.8 mol% which still has quite large space for improvement …”

DMC-Mediated Copolymerization of CO2 and PO—Mechanistic Aspects Derived from Feed and Polymer Composition

“…It seems that the importance of the protonation is not adequately considered in the mechanistic description [116][117][118][119][120][121][122], and with that the susceptibility of a catalyst to incorporate CO 2 in the backbone. This is, so far as we can understand, the catalytic action today, a crucial extension to mechanisms proposed in the open literature [70,[123][124][125][126].…”

Co-Ni Cyanide Bi-Metal Catalysts: Copolymerization of Carbon Dioxide with Propylene Oxide and Chain Transfer Agents

“…The application of non-alternating CO 2 /PO cooligomers is especially attractive because, in some cases, they may substitute poly(propylene glycol)s (PPGs) thereby decreasing the consumption of fossil derived PO [1,22]. Oligo(ethercarbonate)s (structure 4 in Scheme 1) can be efficiently produced by CO 2 /PO cooligomerization in the presence of Zn-Co metal cyanide catalysts and chain transfer agents (CTAs) [22][23][24][25][26][27][28][29][30][31][32][33][34]. Usually, polyols or polycarboxylic acids (structure 5 in Scheme 1) are employed to control molecular weight of the final products.…”