改性磷钨酸及其在生物柴油合成中的催化活性研究  

Study on the catalytic activity of modified phosphotungstic acid in biodiesel synthesis

作　　者：王立勤 唐钰 王锋 曹文秀 WANG Liqin;TANG Yu;WANG Feng;CAO Wenxiu(College of Materials and Chemical Engineering,Hunan City University,Yiyang,Hunan 413000,China)

机构地区：[1]湖南城市学院材料与化学工程学院,湖南益阳413000

出　　处：《湖南城市学院学报（自然科学版）》2023年第5期73-78,共6页Journal of Hunan City University:Natural Science

基　　金：湖南省教育厅科研项目(22C0524)。

摘　　要：采用改变焙烧温度的方式,制备不同酸量、结构的改性磷钨酸催化剂,研究其在生物柴油合成反应中的催化活性,并建立催化剂活性与性质的关系;利用X射线衍射仪和傅里叶变换红外光谱仪对催化剂的结构进行表征,采用间接滴定法对催化剂的总酸量进行表征,以甲醇和油酸的酯化反应为模型反应合成生物柴油﹒结果表明:1)随着焙烧温度的增加,催化剂酸量呈先增加后减小趋势;当焙烧温度为300℃时,磷钨酸酸量达最大值5.63 mmol/g;当焙烧温度小于等于500℃时,磷钨酸依然保持Keggin结构,且随着焙烧温度的提高,结晶度下降;当焙烧温度达600℃时,磷钨酸分解为产物WO_(3),其酸量仅为0.29 mmol/g﹒2)随着催化剂酸量的增加,其在油酸酯化反应中的催化活性提高,且当焙烧温度为300℃时,改性的磷钨酸催化活性最高﹒3)单因素优化试验结果表明,当催化剂用量为2 wt.%,醇油比为10꞉1,反应温度为90℃,反应时间为3 h时,油酸转化率达最大值97.2%.Modified phosphotungstic acid catalysts with different structures and acid amounts were prepared by adjusting the roasting temperature.The catalytic activityof the catalysts in biodiesel synthesis was studied.The relationship between catalyst activity and properties was established.The structure of the catalyst was characterized by X-ray diffractometer and Fourier transform infrared spectroscopy.The total acid content of the catalyst was characterized by indirect titration.Biodiesel was synthesized by esterification of methanol with oleic acid as a model reaction.The results indicate that:1)With the increase of calcination temperature,the acid content of the catalyst increases at first and then decreases.When the calcination temperature is 300°C,the amount of phosphotungstic acid reaches the maximum value 5.63 mmol/g;When the calcination temperature is less than or equal to 500°C,the phosphotungstic acid still retains the Keggin structure,and the crystallinity decreases with the increase of calcination temperature.When the roasting temperature reaches 600°C,the phosphotungstic acid is decomposed into WO_(3)and its acid content is only 0.29 mmol/g.2)The catalytic activity of the catalyst is increased with the increase of the acid amount of the catalysts.When the calcination temperature is 300°C,the catalytic activity of the phosphotungstic acid reaches maximum value.3)The results of single factor optimization test show that when the amount of catalyst is 2%,the ratio of methanol to oil is 10:1,the reaction temperature is 90°C,and the reaction time is 3 h,the oleic acid conversion reaches the maximum of 97.2%.

关 键 词：催化 磷钨酸 油酸 酯化反应 

分 类 号：TQ426[化学工程] TQ645