Preparation, Characterization of Dawson-type Heteropoly Acid Cerium (III) Salt and Its Catalytic Performance on the Synthesis of n-Butyl Acetate

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• 作者：Xiaohua CAO (²ÜС»ª)^a ; ^b ; Jie REN (ÈνÜ)^a ; ^{renjie.r@263.net} ; Changlong XU (Ðì³£Áú)^b ; Kanghua ZHANG (ÕÅ¿µ»ª)^b ; Changchao ZHAN (Õ¼²ý³¯)^a ; ^b ; Jian LAN (À¶½¡)^b
• 关键词：cerous phosphotungstate ; Dawson structure ; catalyst ; esterification ; n-butyl acetate
• 刊名：Chinese Journal of Chemical Engineering
• 出版年：2013
• 出版时间：May, 2013
• 年：2013
• 卷：21
• 期：5
• 页码：500-506
• 全文大小：894 K

文摘

A novel cerium (III) salt of Dawson type tungstophosphoric acid (Ceb>2b>Pb>2b>Wb>18b>Ob>62b>¡¤16Hb>2b>O) was prepared by doping cerous nitrate in Hb>6b>Pb>2b>Wb>18b>Ob>62b>¡¤13Hb>2b>O powder and characterized by thermogravimetry and differential thermal analyses (TG/DTA), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), pyridine infrared spectroscopy (Py-IR) and scanning electron microscopy (SEM). Its catalytic activity was evaluated by the probe reaction of synthesis of n-butyl acetate with acetic acid and n-butanol. The effects of various parameters such as molar ratio of n-butanol to acetic acid, reaction temperature, reaction time, and catalyst amount have been studied by single factor experiment. The results show that Ceb>2b>Pb>2b>Wb>18b>Ob>62b>¡¤16Hb>2b>O behaved as an excellent heterogeneous catalyst in the synthesis of n-butyl acetate. The optimum synthetic conditions were determined as follows : molar ratio of n-butanol to acetic acid at 2.0: 1.0, mass of the catalyst being 1.44 % of the total reaction mixture, reaction temperature of 120 ¡ãC and reaction time of 150 min. Under above conditions, the conversion of acetic acid was above 97.8 % . The selectivity of n-butyl acetate based on acetic acid was, in all cases, nearly 100 % . The catalysts could be recycled and still exhibited high catalytic activity with 90.4 % conversion after five cycles of reaction. It was found by means of TG-DTA and Py-IR that the catalyst deactivation was due to the adsorption of a complex of by-product on the active sites on catalysts surface or the catalyst loss in its separation from the products. Compared with using sulfuric acid as catalyst, the present procedure with Ceb>2b>Pb>2b>Wb>18b>Ob>62b>¡¤16Hb>2b>O is a green productive technology due to simple process, higher yield, catalyst recycling and no corrosion for the production facilities.