【作者】 郁盛健；

【导师】 蒋平平；

【作者基本信息】 江南大学 ， 化学工艺， 2012， 硕士

【摘要】 酯化反应是化学工业中一类非常重要的酸催化反应,可用于合成很多重要的化工原料与中间体。为解决目前工业生产中酯化催化剂存在的分离困难、不可回收、环境污染等突出问题,寻找高活性、低价格、可复用、无污染的新型纳米固体酸催化剂已成为当前研究的热点。本文采用新的合成工艺制备了多种新型纳米固体酸催化剂,并以催化醋酸丁酯的反应为探针,进一步研究了纳米固体酸催化剂在酯化反应中的应用。采用直接研磨法制备了一系列SO₄^2-/ZrO₂型固体酸催化剂。其中无定形的Zr（OH）₄可作为制备纳米SO₄^2-/ZrO₂催化剂载体的优秀前驱体;而采用氨基磺酸为酸化原料制备的催化剂硫含量更高、比表面积更大、活性更强;在最佳煅烧温度500℃下,催化剂呈无定形态,为不规则的纳米网状结构;同时发现酸化剂的加入抑制了ZrO₂四方晶相的形成,随着原料S:Zr摩尔比的增加,催化剂的比表面积和孔容以及SO₄^2-的含量都呈现出先增大后减小的趋势,并且在S:Zr摩尔比为2:1时,催化酯化反应的活性最高,反应30 min,醋酸的转化率即可达到92.71 %,同时重复使用5次,催化活性没有降低。以偏钨酸铵和磷钨酸为W源,采用等体积浸渍法制备了一系列WO_x/ZrO₂型复合金属氧化物催化剂。采用不同W源制备的催化剂都为纳米片状结构,并且用磷钨酸浸渍的催化剂直径更小只有约10 nm;随着煅烧温度的升高,WO₃逐渐析出,催化剂的比表面积降低,单位W密度则随之升高;随着WO₃负载量的增加,ZrO₂由四方相向单斜相转变,催化剂的比表面积先增加之后稍有降低,单位W密度也随之增加。考察了WO_x/ZrO₂催化剂催化合成醋酸丁酯的活性,发现在煅烧温度为750℃,WO₃负载量为10 %时催化酯化活性最高,同时催化剂的重复使用性能良好,可重复4次无明显降低,而活性降低的主要原因是由于催化剂表面积炭,可以通过氧化烧炭法再生。更多还原

【Abstract】 The esterification reaction is an important acid catalytic reaction in chemical industy. And esters are very important chemical intermediates and materials. However the drawbacks traditional acid catalyst suffered are obvious, such as the difficulty for the separation of the catalyst from the reaction mixture, unreusable of catalyst and environmental pollutions. To research a new nanosized solid acid catalyst with high activity, low price, reusability and environmentalfriendly has become a hot topic. This paper adopts a new synthesis process to prepare a series of nanosized solid acid catalysts, and further studied the catalyst activity in the esterification of acetic acid with n-butanol.Nanosized sulfated zirconia has been synthesized by the incorporation method. And the amorphous zirconium hydroxide is an excellent supporter. Catalyst prepared with sulfamic acid gets higher content of sulfate group, bigger BET surface area and higher activity. The catalyst is amorphous phase and displays a disordered structure with a number of wormhole-like and interconnected channels. The presence of sulfate restrains the tetragonal crystal of zirconia. As the increase of the mole rateio of S:Zr, the BET surface area and the content of sulfate group of the catalyst present a first increases, then decreases trends. When S:Zr = 2, the catalytic activity get the highest point. The conversion of acetic acid reaches 92.73 % even with a reaction time of 30 min. The catalyst can be reused as there is no loss in catalytic activity during the five cycles.A series of nanosized tungtated zirconia was prepared by impregnation method with ammonium metatungstate and phosphotungstic acid. The catalysts displayed the nano flake structure, and catalyst prepared by phosphotungstic acid shows smaller diameter only about 10 nm. With the increase of calcination temperature, WO₃ crystals were separated out, and the BET surface area of the catalyst was reduced, and the W surface density was increased. The increasing of the WO₃ load transforms tetragonal phase to monoclinic phase, the W surface density was increased, and the BET surface area of the catalyst present a first increases, then decreases trends. Then we studied the catalyst activity in the esterification of acetic acid with n-butanol. The optimum preparation condition of catalyst is the calcination temperature at 750℃and the WO₃ load is 10 %. The catalyst can be reused as there is little loss in catalytic activity during the four cycles. And can be regeneration by oxidation charcoal burner method.更多还原