Ce cooperated layered double oxide with enhanced base sites activity for the synthesis of polycarbonate diols
Kaiyan Zhao and Xiaowei Tantai contributed equally to this work.
Funding information: CNPC Northeast Refining & Chemical Engineering Co., Grant/Award Number: GKF 20210040
Abstract
The development of highly efficient alkaline catalysts with abundant base sites is of paramount importance for the synthesis of polycarbonate diols (PCDLs). And the application of heterogeneous catalysts is an effective strategy to address the effect of residual catalysts on the quality of PCDLs. Here, Ce cooperated layered double oxide (LDO-Ce) was used as a catalyst for the preparation of PCDLs via transesterification between dimethyl carbonate (DMC) and 1,4-butanediol (BDO). CO2 temperature-programmed desorption (CO2-TPD) profiles demonstrated that the introduction of Ce led to an increase in strong base sites of LDO-Ce, thus endowing LDO-Ce with excellent catalytic performance. Besides, LDO-Ce possessed satisfactory specific surface area and pore size. A possible catalytic mechanism was proposed to illustrate the transesterification process. The effects of the reaction conditions on the hydroxyl value, yield, and BDO conversion were further investigated in detail. The yield of PCDLs with a hydroxyl value of 112.2 mg KOH/g (corresponding to a number average molecular weight [Mn] of 1000 g/mol) was 92.44% under its optimum reaction conditions (w (catalyst) = 0.5%, n(DMC)/n(BDO) = 1.25, T-transesterification = 130°C, t-transesterification = 5 h, T-polycondensation = 170°C, t-polycondensation = 4 h, P-polycondensation = 10 kPa). Moreover, LDO-Ce was easily removed after the transesterification process (Step 1), ensuring the quality of PCDLs, and it was recycled three times without significant loss of catalytic activity.
CONFLICT OF INTEREST
There are no conflicts of interest to declare.
Open Research
DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding author upon reasonable request.