Dawson型磷钨酸/多壁碳纳米管催化合成四氢呋喃

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。

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

H_2P_2W_(18)O_(62)?nH_2 O/multiwalled carbon nanotubes (P_2W_(18)/MWCNTs) catalyst was prepared by impregnation and was used in synthesis of tetrahydrofuran from 1,4-butanediol.The structure of active component P_2W_(18) and the catalyst itself was characterized by means of FITR.P_2W_(18) was proved to be of Dawson structure mainly and the catalyst was proved to be loaded with the P_2W_(18). The effects of catalyst dosage,P_2W_(18) 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,P_2W_(18) mass fraction on P_2W_(18)/ 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 furfura method.