聚碳酸酯在亚临界乙醇中的催化解聚

Catalytic depolymerization of polycarbonate in sub-critical ethanol

以氢氧化钠为催化剂、在投料比1∶6.3（20.0 g PC/126.2 g乙醇）、温度140-220℃、压力1.1-5.9MPa、反应时间15-60 min条件下,利用间歇式高压反应釜研究了聚碳酸酯（PC）在亚临界乙醇中的催化解聚,产物分别采用傅里叶红外光谱（FT-IR）、气质联谱（GC-MS）和气相色谱（GC）进行分析。结果表明,PC的解聚率随温度的升高、反应时间的延长而增加;主产物双酚A（BPA）的收率随反应温度升高、反应时间延长而下降。在投料比1∶6.3、温度170℃、反应时间15 min、压力1.7 MPa、催化剂投加量1.0 g·（160.0 ml乙醇）^-1条件下,PC解聚率为84.2%,BPA收率可达到95.7%。根据PC在亚临界乙醇中催化解聚产物的分析,并结合PC链结特点,提出了PC的催化解聚机理。通过实验数据关联,得出亚临界乙醇中PC催化解聚反应级数为一级,反应活化能为40.15 kJ·mol^-1。

Catalytic depolymerization of polycarbonate （PC） in sub-critical ethanol was performed in a batch reactor under pressures 1.1 MPa to 5.9 MPa and at temperatures 140℃ to 220℃ for 15 min to 60 rain. FT IR, GC-MS and GC were used to analyze the products, and the depolymerization ratio of PC and the yield of bisphenol A （BPA） were estimated. The results showed that the depolymerization ratio of PC increased with the increase of temperature and reaction time, while the yield of BPA decreased because of its decomposition at elevated temperatures and long reaction time. The optimal condition for the yield of BPA was 170℃ and 1.7 MPa, in which the depolymerization ratio of PC reached 84.2% in 15 rain and the yield of BPA was 95.7% of the expected value. Kinetic analysis showed the catalytic depolymerization reaction in sub-critical ethanol was a first-order reaction and its activation energy was 40.15 kJ· mol^-1.