BaFe_(12)O_(19)@(CaO-CaAl_(12)O_(19))磁性固体碱催化甘油制备碳酸甘油酯

Preparation of glycerol carbonate from glycerol catalyzed by magnetic solid base Ba Fe^(12)O^(19)@(CaO-CaAl^(12)O^(19))

以九水硝酸铁、硝酸钡为原料采用溶胶凝胶法得到BaFe_(12)O_(19)前驱体,焙烧浸渍勃姆石溶胶后分散于Ca(NO_3)_2·4H_2O溶液,采用沉淀法合成了磁性固体碱催化剂BaFe_(12)O_(19)@(CaO-CaAl_(12)O_(19))。对其进行了磁滞回线、X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电镜(TEM)、CO_2-TPD表征。将制得的磁性固体碱催化剂应用于甘油和碳酸二甲酯的酯交换反应,考察反应条件对产物收率的影响。结果表明:催化剂有较强的碱强度且活性位包裹均匀、有较好的磁性;在m(Ca(NO_3)_2·4H_2O)∶m(BaFe_(12)O_(19)@AlOOH)=5∶1、反应温度85℃、反应时间2.5 h、n(甘油)∶n(碳酸二甲酯)=1∶5、催化剂用量5%条件下,甘油转化率达到99.43%,碳酸甘油酯收率达到99.38%。

BaFe12O19 precursor was obtained by sol- gel method using iron nitrate nonahydrate and barium nitrate as raw materials, and BaFe12O19 was obtained after calcination. BaFex2019 was impregnated with boehmite sol and dispersed in calcium nitrate tetrahydrate solution and then the magnetic solid base catalyst BaFe12O19@（CaO-CaAl12O19） was synthesized by precipitation method. The catalyst was char- acterized by magnetic hysteresis loop, X -ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and CO2 -TPD. The prepared magnetic solid base catalyst was applied to the transesterification reaction of glycerol and dimethyl carbonate to investigate the effect of different reaction conditions on the yield of the product. The results showed that the catalyst had strong alka- li strength and the active site was wrapped evenly and had better magnetic properties. Under the condi- tions of m（Ca（NO3）2·4H2O）： m（BaFe12O19@ AlOOH） = 5： 1, reaction temperature 85℃, reaction time 2.5 h, n（glycerol） ： n（ dimethyl carbonate） = 1 ： 5 and catalyst dosage 5%, the conversion of glycer- ol reached 99.43%, and the yield of glycerol carbonate reached 99.38%.