Dawson型磷钨酸／多壁碳纳米管催化合成四氢呋喃

Synthesis of Tetrahydrofuran on Phosphotungstic Acid/Multiwalled Carbon Nanotube Catalyst with Dawson Structure

以多壁碳纳米管(MWCNTs)为载体,用浸渍法负载磷钨酸 H_6P_2W_(18)O_(62)·nH_2O(P_2W_(18))制备了 P_2W_(18)/MWCNTs 催化剂,对该催化剂进行了傅里叶变换红外光谱(FTIR)表征,并考察了该催化剂催化1,4-丁二醇液相环化脱水制备四氢呋喃(THF)的性能。FTIR 表征结果表明,P_2W_(18)/MWCNT 催化剂具有 Dawson 型结构。通过正交实验和单因素实验探讨了催化剂用量、P_2W_(18)负载量、反应时间、反应温度对合成反应的影响,优化的工艺条件为:催化剂用量(相对于1,4-丁二醇的质量分数)为2.8%,催化剂中P_2W_(18)负载量(相对于催化剂的质量分数)为50%,反应时间45min,反应温度185～190℃;在此条件下,THF 的收率达96 75%。催化剂重复使用5次后,THF 的收率仍达到92.72%。还提出了该合成反应为碳正离子反应的机理。

H6P2W18O62·nH2O（P2W18） multiwalled carbon nanotubes （ P2W18/MWCNTs ） catalyst was prepared by impregnation and was used in synthesis of tetrahydrofuran from 1,4-butanediol. The structure of active component P2W18 and the catalyst itself was characterized by means of FTIR. P2W18 was proved to be of Dawson structure mainly and the catalyst was proved to be loaded with the P2W18. The effects of catalyst dosage, P2W18 loading amount, reaction time and temperature on the reaction were investigated by orthogonal experiments and single factor experiments. Under the optimized reaction conditions： catalyst mass fraction 2.8% of 1,4-butanediol, P2W18 mass fraction on P2W18/ MWCNTs catalyst 50%, reaction time 45 min and reaction temperature 185 - 190 ℃, yield to tetrahydrofuran can reach 96.75%. The catalyst can be reused for 5 times and yield to tetrahydrofuran keeps at 92. 72%. The carbonium ion reaction mechanism was presented. The process has the advantages of 1 ower investment, lower catalyst consumption, high yield and high product quality than the conventional furfural method.