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以Dawson型磷钨酸钇(Y_2P_2W_(18)O_(62)·nH_2O)为活性组分,多壁碳纳米管(MWCNTs)为载体,通过浸渍法制备了负载型磷钨酸钇催化剂。利用FTIR,XRD,SEM,TG,Py-IR,NH3-TPD,N2吸附-脱附等手段对催化剂进行表征,考察了催化剂催化正丁醇与乙酸液相反应合成乙酸正丁酯的性能。表征结果显示,催化剂具有Dawson结构,且同时具有Br觟nsted酸中心和Lewis酸中心,与Y_2P_2W_(18)O_(62)·nH_2O相比,催化剂出现了弱酸中心,总酸量减小,催化剂的比表面积及热稳定性均明显提高。实验结果表明,在n(正丁醇)∶n(乙酸)=2.0∶1.0、催化剂用量为反应物的1.7%(w)、反应温度125℃、反应时间2.0 h的条件下,酯化率为97.4%。催化剂重复使用5次时,酯化率仍可达80.7%。
Dawson-type yttrium phosphotungstate (Y_2P_2W_ (18) O_ (62) · nH_2O) as active component and multi-walled carbon nanotubes (MWCNTs) as carrier were prepared by impregnation method. The catalysts were characterized by means of FTIR, XRD, SEM, TG, Py-IR, NH3-TPD and N2 adsorption-desorption. The catalytic performance of the catalysts for the synthesis of n-butyl acetate from n-butanol and acetic acid was investigated. The characterization results show that the catalyst has a Dawson structure with both Brünsted acid sites and Lewis acid sites. Compared with Y_2P_2W_ (18) O_ (62) · nH_2O, the catalyst has a weak acid site and a reduced total acid amount. Specific surface area and thermal stability were significantly improved. The experimental results show that under the condition of n (n-butanol): n (acetic acid) = 2.0:1.0, the amount of catalyst is 1.7% (w), the reaction temperature is 125 ℃ and the reaction time is 2.0 h, 97.4%. When the catalyst is reused 5 times, the esterification rate still reaches 80.7%.