Preparation of compound magnetic Fe3O4/MgAl-layered double hydroxide and its application in biodiesel transesterification
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摘要: 使用共沉淀法制备磁性Fe3O4粒子,并以此为原料制备出Fe3O4/MgAl-LDH,将其焙烧产物Fe3O4/Mg(Al)O作为微藻油脂和甲醇发生酯交换反应的催化剂,利用产物生物柴油产率作为评价催化剂的活性指标,探究其酯交换活性。通过TG-DTG、XRD、SEM、EDS、TEM、N2吸附-脱附、VSM等表征手段对所制备样品进行表征。结果表明,MgAl-LDH、Mg(Al)O在Fe3O4表面生长,并具有一定的磁响应能力。在反应时间为4 h、醇油物质的量比为13:1的条件下,生物柴油产率高达90%。经过三次使用后,仍具有一定活性。在外磁场的作用下可完成催化剂与反应物的分离。Abstract: Magnetic Fe3O4 was synthesized by chemical coprecipitation method, and used as a raw material for preparing Fe3O4/MgAl-LDH. The calcined Fe3O4/Mg(Al)O was taken as the catalyst for the transesterification of microalgae oil with methanol, and the biodiesel yield was used to evaluate the activity of the catalyst. Several instruments including TG-DTG, XRD, SEM, EDS, TEM, N2 absorption-desorption and VSM were employed to characterize the catalysts. The results show that MgAl-LDH and Mg(Al)O are successfully formed on Fe3O4 particles which have a strong magnetic response. When the reaction time is 4 h and the methanol/oil mol ratio is 13:1, the biodiesel oil yield reaches to 90%. After using for three times the catalyst still has certain activity and can be easily separated and recycled.
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Key words:
- biodiesel /
- magnetism /
- transesterification /
- hydrotalcite
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表 1 微藻油脂的理化性质
Table 1 Physical and chemical properties of microalgae oil
Number Acid value w/(mgKOH·g-1) Saponification value w/(mgKOH·g-1) Moisture and volatile matter x/% Average molecular weight q/(g·mol-1) 1 0.93 188.346 0.18 898.00 2 0.93 188.137 0.18 899.00 3 0.94 188.570 0.17 896.00 Average value 0.93 188.351 0.18 898.00 表 2 不同样品的比表面积和孔结构
Table 2 Results of N2 absorption-desorption measurements for different samples
Catalyst BET surface area A/(m2·g-1) Total pore volume v/(cm3·g-1) Pore size d/nm Mg(Al)O 138 0.62 11.15 Fe3O4/ Mg(Al)O 228 0.92 13.50 -
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