摘要
通过研究反应温度、反应时间和催化剂用量对尿素与1,2-丙二醇(PG)合成碳酸丙烯酯(PC)的影响,考察6种镧化合物的催化活性;用FTIR方法对反应路径进行研究;用XRD、TGA和元素分析等方法对反应后所得黄色沉淀物进行表征,推断合成PC的反应机理。实验结果表明,尿素与PG合成PC的反应为两步反应:第一步为尿素经异氰酸与PG生成中间产物2-羟丙基氨基甲酸酯(HPC),第二步为HPC转化成PC(动力学控制步骤);La Cl3催化剂的活性最高,在160℃、3 h、La Cl3用量2.3%(w,基于体系的质量)的反应条件下,尿素转化率和PC收率可分别达到96.9%和94.3%。表征结果显示,在反应过程中La Cl3能溶于反应体系,La3+可与NH3分子发生络合形成活性中间化合物La(NH3)3Cl3,有利于HPC转化为PC。
The catalytic activities of six lanthanum compounds for the synthesis of propylene carbonate（PC） from urea and 1, 2-propylene glycol（PG） were evaluated and the effects of reaction temperature, reaction time and catalyst dosage on the PC synthesis were investigated. The reaction paths were studied by means of FTIR. Some yellow precipitant was obtained after the synthesis and then was characterized by means of XRD, TGA and elemental analysis to study the reaction mechanism. The experimental results showed that the synthesis of PC from urea and PG could be divided into two steps： firstly, urea was converted into isocyanate species, which reacted with PG to form an intermediate, 2-hydroxypropyl carbamate（HPC）, and then HPC was converted into PC（dynamic control step）. Among these catalysts, LaCI3 exhibited the highest catalytic activity. Under the optimal reaction conditions of 160 ℃, 3 h and catalyst dosage 2.3%（w, based on the weight of the reaction system）, the urea conversion and PC yield could reach 96.9% and 94.3%, respectively. In addition, the characterization results demonstrated that LaC13 could be dissolved in the reaction system, and a complex, La（NH3）3Cl3, formed, which was beneficial to the HPC conversion to PC.
出处
《石油化工》
CAS
CSCD
北大核心
2015年第10期1182-1187,共6页
Petrochemical Technology
基金
中国科学院战略性先导科技专项资金项目(XDA05010108)
山东省自然科学基金项目(ZR2012BL07
ZR2012BL06
ZR2013BL019)
山东省优秀中青年科学家科研奖励基金项目(BS2011SF026)
枣庄学院国家级大学生创新创业训练计划项目(311190805
311190806)
关键词
尿素
1
2-丙二醇
碳酸丙烯酯
氯化镧催化剂
urea
1, 2-propylene glycol
propylene carbonate
lanthanum chloride catalyst
