【作者】 王栩；

【导师】 张增强；

【作者基本信息】 西北农林科技大学 ， 应用化学， 2010， 硕士

【摘要】 生物柴油是一种环境友好型、可再生、易于生物降解的绿色环保燃料。目前多采用大豆油、菜籽油等动植物油脂的酯交换反应制备,可以通过均相催化及非均相催化两种方式,其中非均相催化剂由于易再生、可循环使用,对设备腐蚀性小,后处理简便等优点,可以明显简化工艺环节,降低生产成本,是近年来的研究热点。常用的非均相催化剂可以分为固体酸催化剂及固体碱催化剂,其中后者催化活性高,反应时间短,反应条件温和,后处理简便,因此受到广泛重视。粉煤灰是燃煤电厂排出的工业废渣,它的主要成份是SiO₂和Al₂O₃,具有吸附、离子交换性能,因此粉煤灰可以作为良好的催化剂载体,目前普遍使用的催化剂载体是氧化铝、氧化钙、氧化镁、氧化硅、二氧化钛、分子筛等,关于粉煤灰负载型催化剂并未大规模研究应用。本实验通过浸渍法制备了一系列应用于生物柴油酯交换反应的粉煤灰负载型催化剂,选择了碱金属和碱土金属氢氧化物、硝酸盐、碳酸盐、醋酸盐、氨化物等多种负载的前驱体,从中筛选出具有最高催化活性的催化剂,测定碱强度以及总碱量（H_≥35）,并运用SEM,IR,XRD等多种测试手段对其结构进行了分析表征,利用正交实验方法分别对其制备条件以及酯交换反应的条件进行优化。实验结果表明,在该系列催化剂中,NaOH/NaNO₃/粉煤灰负载型催化剂对棉籽油合成生物柴油的酯交换反应具有最高的催化活性,通过正交实验得到该催化剂最佳制备条件为NaOH含量为20%、NaNO₃含量为20%、催化剂煅烧温度270℃、煅烧时间4h;该催化剂催化棉籽油的酯交换反应的最佳反应条件为:醇油摩尔比为10:1,反应温度为70℃,反应时间为80min,催化剂用量为1.2%。当将该催化剂在此条件下应用于棉籽油的酯交换反应时,棉籽油的转化率可达到98.75%,并且催化剂在重复使用四次后,活性基本不变,可以循环使用。通过碱强度测定和结构表征,证明该固体碱催化剂已经具有活性中心,固体碱催化剂碱强度高达H_≥43,总碱量（H_≥35）达到5.12mmol/g,符合固体碱的定义。利用粉煤灰作为生物柴油催化剂的载体,体现了废物的再利用,即减轻了环境压力,又能缓解能源危机,因此本研究成果具有较大的实用和经济价值。更多还原

【Abstract】 Biodiesel was environment-friendly renewable and easy-to-biodegradable. It is produced by transesterification of soybean oil, rapeseed oil and other animal or plant oil with methanol in the presence of homogeneous and heterogeneous catalyst. Traditional biodiesel production technologies of homogeneous catalysts had deficiencies, such as difficult to separate catalysts and bring about some environmental problems. So the research focus on the heterogeneous catalyst in recent years. Common heterogeneous catalysts can be divided into solid acid catalyst and solid base catalyst. The solid base catalyst was higher catalytic activity so could short the reaction time. And the reaction conditions were mild too.Coal fly ash is discharged from industrial waste of coal-fried power plant. It mostly contains SiO₂ and Al₂O₃ with adsorption and ion-exchange properties. Therefore, fly ash can serve as a good catalyst carrier. The main catalyst carrier concludes alumina, calcium oxide, magnesium oxide, silica, titanium dioxide, zeolite and so on. Catalysts with fly ash as carrier were not applied widely.A series of solid base catalysts with fly ash as carrier were prepared by impregnation and applied into the biodiesel production. Chose alkali metal and alkaline earth metal hydroxide, nitrate, carbonate, acetate, hydrazine as the precursor loaded on fly ash. The catalyst which has the highest activity was obtained, and its base strength and the total alkali content （H_≥35） was determinate. The catalyst was also analyzed and characterized by SEM, IR and XRD. Orthogonal analysis can optimize the best preparation conditions for the highest activity of the catalyst.The results showed that the catalyst with NaOH and NaNO₃ loaded on fly ash has the highest activity. The optimum conditions for catalyst preparation were obtained as follows: NaOH content of 20%, NaNO₃ content of 20%, the catalyst calcination temperature of 270℃and the calcination time of 4h. The optimum reaction conditions for the transesterification between cottonseed oil and methanol were determined as methanol/oil mole ratio of 10:1, catalyst dosage（catalyst/oil） of 1.2%, reaction time of 80min and reaction temperature of 70℃. The base catalyst exhibits excellent catalytic activity and the conversion of biodiesel production reaches over 98.75% under the optimum reaction conditions. After the catalyst was used repeatedly four times, the activity decreased less. The characterization showed that the catalyst had active sites. The highest base strength （H- ）of the base catalyst reaches over 43, and the basicity is 5.12mmol/g. Using fly ash as a carrier of biodiesel catalyst reflects the recycling of waste, reduces the environmental pressure, eases the energy crisis. Therefore, this study has great practical and economic value.更多还原