Ohashi Yasunori, Watanabe Takashi
Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
ACS Omega. 2018 Nov 29;3(11):16271-16280. doi: 10.1021/acsomega.8b01454. eCollection 2018 Nov 30.
The development of a novel pretreatment system using catalysts with high safety and low cost is pivotal to establish lignocellulosic biorefinery. We evaluated 16 Lewis acid catalysts for microwave solvolysis pretreatment to enhance enzymatic saccharification of woody biomass and found that very cheap and safe food additives, alum, are effective for the pretreatment, giving high sugar yield comparable to that of AlCl, a strong Lewis acid catalyst effective both for softwood and hardwood. In microwave solvolysis of Japanese cedar, and using alum in ethylene glycol/water (9/1, w/w), the maximum sugar yields after enzymatic saccharification reached 47.8, 51.0, and 59.7% based on the weight of each wood. The same reactions in glycol/water (9/1, w/w) gave the sugar yield, 34.5, 54.1, and 58.5%, indicating differential reactivity of the Lewis acid/solvent system depending on wood species. We found that efficiency and selectivity of pretreatment with a flocculating and astringent agent, Al(SO), was promoted by microwave. Reaction of Japanese beech wood with Al(SO) in 50% aqueous 1-propanol by microwave and conventional heating revealed that microwave irradiation suppressed excessive degradation of carbohydrates into furfural derivatives. Saccharification of the wood pretreated by microwave with 8 and 1 filter paper units of cellulolytic enzymes gave sugar yields per wood of 50.3 and 43.9%, whereas the same reaction in an autoclave resulted in 48.9 and 34.7% yields, demonstrating that microwave irradiation accelerated the saccharification and the effect was remarkable with a lower enzyme dosage.
开发一种具有高安全性和低成本的新型预处理系统对于建立木质纤维素生物精炼厂至关重要。我们评估了16种用于微波溶剂分解预处理以提高木质生物质酶糖化的路易斯酸催化剂，发现非常便宜且安全的食品添加剂明矾对预处理有效，其糖产率与AlCl相当，AlCl是一种对软木和硬木均有效的强路易斯酸催化剂。在日本雪松的微波溶剂分解中，以及在乙二醇/水（9/1，w/w）中使用明矾，酶糖化后的最大糖产率分别达到各木材重量的47.8%、51.0%和59.7%。在乙二醇/水（9/1，w/w）中的相同反应给出的糖产率分别为34.5%、54.1%和58.5%，表明路易斯酸/溶剂体系的反应活性因木材种类而异。我们发现微波促进了絮凝剂和收敛剂Al₂(SO₄)₃预处理的效率和选择性。通过微波和传统加热使日本山毛榉木材与Al₂(SO₄)₃在50%的1-丙醇水溶液中反应，结果表明微波辐射抑制了碳水化合物过度降解为糠醛衍生物。用8和1滤纸单位的纤维素分解酶对经微波预处理的木材进行糖化，每木材的糖产率分别为50.3%和43.9%，而在高压釜中进行相同反应的产率为48.9%和34.7%，这表明微波辐射加速了糖化，并且在较低酶用量下效果显著。
