Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
Bioresour Technol. 2016 Nov;219:338-347. doi: 10.1016/j.biortech.2016.08.002. Epub 2016 Aug 3.
This study aimed to transform food waste into a value-added chemical, hydroxymethylfurfural (HMF), and unravel the tangled effects induced by the metal catalysts on each single step of the successive conversion pathway. The results showed that using cooked rice and bread crust as surrogates of starch-rich food waste, yields of 8.1-9.5% HMF and 44.2-64.8% glucose were achieved over SnCl4 catalyst. Protons released from metal hydrolysis and acidic by-products rendered Brønsted acidity to catalyze fructose dehydration and hydrolysis of glycosidic bond. Lewis acid site of metals could facilitate both fructose dehydration and glucose isomerization via promoting the rate-limiting internal hydride shift, with the catalytic activity determined by its electronegativity, electron configuration, and charge density. Lewis acid site of a higher valence also enhanced hydrolysis of polysaccharide. However, the metals also catalyzed undesirable polymerization possibly by polarizing the carbonyl groups of sugars and derivatives, which should be minimized by process optimization.
本研究旨在将食物垃圾转化为增值化学品羟甲基糠醛（HMF），并揭示金属催化剂对连续转化途径中每个单一步骤所产生的复杂影响。结果表明，使用煮熟的米饭和面包皮作为富含淀粉的食物垃圾的替代物，在 SnCl4 催化剂的作用下，HMF 的产率为 8.1-9.5%，葡萄糖的产率为 44.2-64.8%。金属水解释放的质子和酸性副产物产生了 Brønsted 酸度，从而催化果糖脱水和糖苷键水解。金属的路易斯酸位可以通过促进限速的内部氢迁移来促进果糖脱水和葡萄糖异构化，其催化活性取决于其电负性、电子构型和电荷密度。较高价态的路易斯酸位还可以通过极化糖和衍生物的羰基来促进多糖的水解。然而，金属也可能通过极化糖和衍生物的羰基来催化不必要的聚合反应，这可以通过工艺优化来最小化。
