Modification of Zn-Co DMC catalyst and its application in the synthesis of poly(ether-carbonate) polyols
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摘要: 双金属氰化物(double mental cyanide,DMC)是一种用于二氧化碳与环氧丙烷(PO)共聚反应的催化剂。DMC催化剂是具有晶体结构的有机金属配合物,其催化活性与结晶度密切相关。加入配体、共配体能够破坏立方晶体结构、增加无定形态结构从而降低结晶度。研究证明,以叔丁醇为配体的DMC催化剂活性较高,但是对共配体的使用则鲜有报道。本研究使用不同共配体(Span80、Tween80、D400、D2000)对DMC催化剂改性以达到两个目的:一是降低结晶度,提高催化剂活性;二是减小催化剂粒径。此外,利用PO与CO2的共聚反应对催化剂性能进行考察。结果表明,使用D2000作为共配体改性后的DMC+D2000催化剂,催化活性为1547 g/gcat,聚合产物中碳酸酯单元占聚合部分的质量分数为25.3%,选择性为92.1%。Abstract: Double mental cyanide (DMC) is a catalyst for the ring-opening copolymerization of carbon dioxide and propylene oxide. DMC catalysts are organometallic complexes with crystal structure, and their catalytic activity is closely related to crystallinity. The addition of ligand and co-ligand can destroy the cubic crystal structure, increase the amorphous structure and reduce the crystallinity. A number of studies have proved that tert-butanol as the ligand DMC catalyst has high activity, but there are few reports on the use of co-ligand. In this paper, DMC catalyst was modified with different co-complexing agents (Span80, Tween80, D400, D2000), which decrease crystallinity, catalyst particle size and eventually increase catalyst activity. The properties of the catalyst were investigated by copolymerization of PO with CO2. The results showed that the catalytic activity of DMC+D2000 modified with D2000 as co-ligand was 1547 g/gcat. The molar fraction of carbonate unit in the polymerization product was 25.3%, and the selectivity was 92.1%.
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Key words:
- double mental cyanide catalyst /
- crystallinity /
- CO2
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表 1 共配体的种类及结构
Table 1 Types and structures of co-complexing agents
Types Mn Functional group Solubility Structure Span80 428 –OH + Tween80 1365 –OH +++ D400 400 –NH2 ++ D2000 2000 –NH2 – Solubility:Degree of dissolution of the sample in water,(+):soluble;(–):insouble 表 2 不同条件下CO2与 PO共聚反应
Table 2 Copolymerization of PO and CO2 catalyzed under different conditions
Entry CTA/PO (mass ratio) Reaction period/h t/℃ p/MPa Mna/(g·mol−1) CU' b/mol% Selectivityc s/% 1 0.25 20 80 2 1058 19.0 94.7 2 0.25 12 80 2 1204 23.8 91.8 3 0.16 12 80 2 2109 21.2 92.2 4 0.25 12 70 2 791 14.1 95.4 5 0.25 12 90 2 1820 25.2 82.7 6 0.25 12 100 2 1915 15.1 82.9 7 [18] 0 4 80 0.5 6700 0 - 8 [25] 0.048 10 80 3.8 6050 32.0 5 The Zn-Co double mental cyanide catalyst was used in copolymerization; entry1 is one-step method, entries 2–6 are continuous method;
a: Mn=56.1*1000f /Qv; b: the molar fraction of carbonate linkages in the produced polymer; [carbonate]/([carbonate] + [ether]) ratio determined by 1H NMR spectra;
c: the weight percentage of poly(ether-carbonate) polyols in the total crude product表 3 不同催化剂作用的CO2与 PO共聚反应a
Table 3 Copolymerization of PO and CO2 catalyzed by different catalysts a
Entry Catalyst Mnb/(g·mol−1) ${f}_{ {\rm{CO} }_2}^{\prime }$c/mol/% CU' d/mol/% Selectivitye s/% PDIf Yieldg/(g·${\rm{g}}^{-1}_{\rm{cat}} $) 1 DMC 1204 19.2 23.8 91.8 1.24 1235 2 DMC+S80 603 32.9 42.9 87.4 1.22 646 3 DMC+T80 1148 16.6 19.8 95.0 1.27 1079 4 DMC+D2000 1679 20.1 25.3 92.1 1.30 1547 5 DMC+D400 803 34.8 53.3 89.4 1.50 934 a: Reaction conditions: W(catalyst)=40 mg, CTA/PO (mass ratio)=0.25; stage of activation: t1=120 ℃; the stage of adding ingredients: t2=80 ℃, p2=2.0 MPa, t2=10 h; b: Mn=56.1*1000f /Qv; c: the molar fraction of carbon dioxide insertion in the produced polymer; d: the molar fraction of carbonate linkages in the produced polymer; e: the weight percentage of poly(ether-carbonate) polyols in the total crude product; f: Polydispersity index determined by gel permeation chromatograph; g: Yield/% = mPO/ mcat 表 4 不同催化剂催化CO2与 PO共聚反应对比
Table 4 Comparison of different catalysts for the copolymerization of PO and CO2
No. co-complexing
agentCTA/PO/DMC
(g/g/mg)CTA t(℃)/
p(MPa)Mna/
(g·mol−1)CU' b/
mol%Selectivityc
s/%PDId 1[17] − 47/76/100 PPG400 80/2 1020 25 94.9 1.06 2[25] − 2.5/25.6/10 H2O 80/5 15200 58 79.5 2.3 3[28] − 13/83/10 BPA 95/4 2000 31 87 2.88 4[29] PEG1000 30/90/41 PPG725 105/2 2660 9.4 99.6 5.97 5 D2000 30/120/60 PPG400 80/2 1679 25 92.1 1.3 a: Mn=56.1*1000f/ Qv; b: the molar fraction of carbon dioxide insertion in the produced polymer; c: the molar fraction of carbonate linkages in the produced polymer; d: the weight percentage of poly(ether-carbonate) polyols in the total crude product -
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