焦磷酸盐-磷酸盐复合催化剂高效催化乳酸脱水制丙烯酸

利用沉淀法制得焦磷酸盐与磷酸盐在浆状态下复配制备成复合催化剂,并用于催化乳酸脱水制丙烯酸.实验发现催化剂的组成对乳酸的转化率及丙烯酸的选择性有着重要的影响,当磷酸盐/焦磷酸盐质量比在30∶70～50∶50范围内,可以获得较高的乳酸的转化率和丙烯酸的选择性.催化反应条件如反应温度,乳酸进料浓度,液空速也被详细地进行了考察.此外,考察了该复合催化剂的稳定性.当催化剂连续运行56 h后,乳酸的转化率保持在96%以上,丙烯酸的选择性也高达57%.为了进一步揭示催化剂的结构与催化性能之间的关系,利用X射线粉末衍射、热重、扫描电镜和傅立叶红外等对催化剂进行了表征.

Highly efficient pyrophosphate/phosphate catalyst for the dehydration of lactic acid to acrylic acid

An efficient catalyst composed of calcium pyrophosphate and calcium phosphate was developed to catalyze dehydration of lactic acid to acrylic acid. The catalyst compositions have a drastic influence on conversion of lactic acid and selectivity toward acrylic acid. When the catalyst composition in mass ratio of calcium phosphate to calcium pyrophosphate was changed from 30 : 70 to 50 : 50, higher conversion of lactic acid and higher selectivity toward acrylic acid were achieved. Other parameters such as reaction temperature, lactic acid concentration, liquid hourly space velocity, were also discussed. In addition, as one of the most important factors for heterogeneous catalysts, the stability of catalyst was checked. After running 56 hours, the conversion of lactic acid yet maintained above 96%, and the selectivity of acrylic acid also maintained above 57%. Characterizations of the catalysts were performed by XRD, TG, SEM, and FTIR.