摘要
用共沉淀法制备了Ca-Al类水滑石并高温焙烧制得Ca-Al复合氧化物,将KF.2H2O和Ca-Al复合氧化物一起研磨并干燥得到KF/Ca-Al固体碱催化剂。采用正交试验考察了各因素对KF/Ca-Al固体碱催化活性的影响,得到的优化条件为:n(NaOH)/n(Na2CO3)为8,n(Ca)/n(Al)为3,焙烧温度为923 K,焙烧时间为9 h。以优化条件下制得的KF/Ca-Al固体碱为催化剂,在n(醇)/n(油)为9,m(催化剂)/m(油)为0.04,反应温度为338 K,反应时间为1 h的条件下,蓖麻油转化率可达98.5%。采用Hammett指示剂法、XRD、TG-DTG、SEM对Ca-Al类水滑石、KF/Ca-Al固体碱进行表征。结果表明:KF/Ca-Al固体碱强度(H-)在7.2～18.4之间;KF/Ca-Al固体碱由KCaCO3F、KCaF3、CaAl2F4(OH)及Ca3Al2(OH)12晶相构成;Ca-Al类水滑石在300～680 K及680～1 000 K有2个明显的失重台阶;KF/Ca-Al固体碱呈不规则孔状结构。
Ca-Al composite oxide is prepared by high temperature calcination of Ca-Al hydrotalcites obtained by coprecipitation method, then grinded together with KF .2H2O to produce KF/Ca-Al solid base catalyst. The influence factors on catalytic activity of KF/Ca-Al solid base catalyst are studied by orthogonal experiments. The optimal conditions are ：8 molar ratio of NaOH and Na2CO3 ,3 molar ratio of Ca and Al,923 K of calcination temperature and 9 hours of calcination time. Using obtained KF/Ca-Al as catalyst for conversion of Castor oil to biodiesel, the conversion rate of Castor oil can reach 98% under the following conditions ：9 molar ratio of alcohol and oil ,0. 04 molar ratio of catalyst and oil ,338 K of reaction temperature and 1 hour of reaction time. Hammett indicator method, XRD, TG-DTG and SEM are used to characterize the structures of the hydrotalcite and KF/Ca-Al solid base catalyst. The results show that base strength （H） of KF/Ca-Al solid base is around 7. 2- 18.4. The solid base catalyst is composed of KCaCO3 F, KCaF3, CaAl2F4 （OH） and Ca3 Al2 （OH）12 crystal phases. Ca-Al hydrotalcite has two obvious loss-weight stages around 300 -680 K and 680 - 1 000 K. KF/Ca-Al shows the irregular hole structure.
出处
《现代化工》
CAS
CSCD
北大核心
2013年第5期74-78,共5页
Modern Chemical Industry
基金
山西省高校科技开发项目(2010130)
