综述了目前聚3-羟基丁酸酯(poly-3-hydroxybutyrate,PHB)的几种主要降解技术,包括热裂解、水解、溶剂降解和酶解等.重点介绍了各种降解技术的产物分布和反应机理,并对影响PHB热稳定性的主要因素进行了总结和讨论.各种技术的所需反应温度总体趋势为:热裂解>水解≥溶剂降解>酶解.PHB热解工艺简单,通常情况下PHB主要降解为巴豆酸和其低聚物,过高反应温度(>500℃)则使PHB分解为二氧化碳和丙烯.水解和溶剂降解都是以针对性地断开PHB酯键为出发点,以获得高产率的PHB单体(3 -羟基丁酸、巴豆酸)或其酯类化合物(如巴豆酸甲酯).与热解、水解和溶剂降解技术相比,酶解法限制因素较多且工艺成本高,需要新的技术突破.提出了两个需进一步重点研究的方向:①PHB 催化热解脱羧制备高品位液体燃料;②直接转化富含PHB的微生物为高价值化学品.%This paper reviewed the main technologies for PHB depolymerization,including pyrolysis, hydrolysis,solvent treatment,and enzymolysis. The effect of process parameters,product distribution, and reaction mechanism on PHB depolymerization were discussed. The main factors affecting the PHB thermal stability were summarized. The required temperatures for a routine reaction are in the following order of:pyrolysis>hydrolysis≥solvent treatment>enzymolysis. Crotonic acid and its oligomers are usually the main products of pyrolysis at mild temperatures. However,a high pyrolysis temperature (e.g.,>500℃)would lead to a high yield of CO2 and propylene. Both hydrolysis and solvent treatment are mainly used to obtain targeted chemicals(e.g.,3-hydroxybutyric acid,crotonic acid,methyl crotonate),by selectively opening the ester bond in PHB. Compared with the other three technologies, new technical breakthrough is needed for enzymolysis due to its multiple limitations and high cost. Two potential research areas were proposed for further work:①catalyzed reforming of PHB for high-quality oil production,and ②direct conversion of PHB rich-in microbial biomass for valuable chemicals.
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