镁铁水滑石的制备及其对小球藻油脂合成生物柴油的催化性能

摘要

MgFe-hydrotalcites (MgFe-LDH) were prepared by using improved urea method and used as the catalysts in the synthesis of biodiesel oil from chlorella protothecoides oil. The hydrotalcites were characterized by XRD, FT-IR, SEM as well as Fourier self-deconvolution and band curve-fitting analyses;the effects of pH value, Mg/Fe mol ratio, temperature and time to prepare the hydrotalcites on their properties and catalytic performances were investigated. The results showed that the MgFe-LDH with Mg/Fe mol ratio of 3 and 4 (Mg3Fe and Mg4Fe), prepared at 110℃ and pH value of 9. 5 for 10 h exhibits high symmetrical crystalline structure. The brucite-like layer of Mg3Fe and Mg4Fe hydrotalcites are stable under calcination for a completely decomposition, compared with the Mg2Fe hydrotalcite with Mg/Fe mol ratio of 2, Mg3Fe and Mg4Fe upon calcination exhibit higher crystallinity and more active sites and higher catalytic activity. For the synthesis of biodiesel oil from chlorella protothecoides oil over the Mg3Fe catalyst, with methanol/oil molar ratio of 6 in the feed, the biodiesel oil yield reaches 87% after reaction 1.5 h;the catalyst can be reused for three times without serious deactivation.%用改良尿素法制备了镁铁水滑石(MgFe-LDH),对其在小球藻油脂合成生物柴油反应中的催化性能进行了研究.利用XRD、FT-IR、SEM及FT-IR拟合、去卷积分析等技术对所制备的MgFe-LDH进行了表征,考察了pH值、Mg/F摩尔比、反应温度和时间对其结构和性能的影响.结果表明,Mg/F摩尔比为3或4、pH值为9.5,在110℃条件下反应10h,所制备的MgFe-LDH(Mg3Fe或Mg4Fe)结晶度最高,粒径均匀,结构规整.与Mg/Fe摩尔比为2的MgFe-LDH(Mg2Fe)相比,Mg3Fe或Mg4Fe在完全分解焙烧时,其层板结构保持稳定,具有较高的晶体结晶度、较多的催化活性位和较高的催化活性.以Mg3Fe金属氧化物为催化剂,在醇/油摩尔比为6时反应1.5h,生物柴油产率可达87％；该催化剂循环使用3次,仍具一定催化活性.