微波辅助的金属氯化物Lewis酸催化纤维素水解

Microwave-assisted hydrolysis of cellulose using metal chloride as Lewis acid catalysts

研究了微波辐射下四种金属氯化物Lewis酸的催化纤维素酸水解反应性能,发现CuCl2的催化性能最好。反应温度、反应时间、微波功率、催化剂用量和酸种类对纤维素水解转化率、葡萄糖和5-羟甲基糠醛(5-HMF)的选择性均有明显影响。与传统热反应相比,微波辐射明显加快纤维素酸水解速率,提高葡萄糖的选择性。0.5g纤维素和15g水,在微波功率800W,温度到达225℃时立即停止反应的条件下,当CuCl2用量为0.05mmol时,纤维素转化率和葡萄糖选择性达72.6%和62.3%;当CuCl2用量为0.15mmol时,5-HMF的选择性最高为13.2%;当CuCl2用量为0.30mmol时,纤维素的转化率高达90.6%,但葡萄糖选择性只有6.7%。

The hydrolysis of cellulose under microwave irradiation using various metal chlorides as Lewis-acid catalysts was investigated. It was found that the cellulose conversion and product selectivity is strongly dependent on the reaction parameters like reaction temperature, time, microwave power, chloride type and amount used. In comparison with the conventional heating method, the microwave irradiation can accelerate the cellulose hydrolysis and improve the selectivity to glucose with good conversion. Among the metal chlorides investigated, copper chloride is the best catalyst for the hydrolysis of cellulose. For 0.5 g of cellulose in 15 g of water, when quitting the reaction once the temperature reached 225 ℃ under a microwave power of 800 W, the cellulose conversion reached 72.6% with a glucose selectivity of 62.3% by using 0.05 mmol of copper chloride as catalyst; the increase of the copper chloride amount to O. 15 mmol led to a selectivity of 13.2% to 5-hydroxymethyl-2-furaldehyde （5-HMF） ; the further increase of the copper chloride amount to 0.30 mmol resulted in a cellulose conversion as high as 90.6% but a glucose selectivity of only 6.7%.