摘要
以六水合硝酸锌、三水合硝酸铜、尿素为原料,采用水热法制备了不同铜锌物质的量比n(n=1/4、3/7、2/3、1和3/2,对应铜摩尔分数分别为20%、30%、40%、50%和60%)的铜-氧化锌催化剂,用SEM、XRD、H2-TPR、BET等方法对铜-氧化锌催化剂进行了结构表征。研究了铜摩尔分数对催化剂形貌及乙酸乙酯加氢反应的影响。结果表明,水热法制得的铜-氧化锌催化剂均为纳米片自组装成的开放型纳米花结构。当铜摩尔分数为40%时,纳米片厚度小于50 nm,纳米花直径约10μm,乙酸乙酯转化率最高,铜摩尔分数过低或过高时加氢活性下降。表征发现,铜摩尔分数为40%的催化剂中铜与氧化锌的结合强度适中,活性位分散均匀。考察了水热条件对催化性能的影响,在最优水热条件(130℃、10h)下合成的催化剂乙酸乙酯转化率达到94%[加氢反应条件为220℃、氢气压力3 MPa、氢气与乙酸乙酯物质的量比20、液时空速2.0 g酯/(g催化剂·h)]。在催化剂稳定性(300 h)测试中乙酸乙酯转化率保持在92%以上。
Cu-ZnO catalysts with different Cu-Zn molar ratios(n=1/4, 3/7, 2/3, 1 and 3/2, corresponding to copper molar fraction of 20%, 30%, 40%, 50% and 60%) were prepared by hydrothermal method using zinc nitrate hexahydrate, copper nitrate trihydrate and urea. The structure of Cu-ZnO catalysts was characterized by SEM, XRD, H2-TPR and BET techniques. The effects of copper molar fraction on the morphology of catalyst and hydrogenation of ethyl acetate were studied. The results showed that the prepared Cu-ZnO catalysts were open nanometer flower structures which are self-assembled by nanometer sheets. When the copper molar fraction was 40%, the thickness of the nanosheet was less than 50 nm, the diameter of the nanoflower was about 10 μm, and ethyl acetate had the highest conversion rate. When the molar fraction of copper was too high or too low, the hydrogenation activity of ethyl acetate decreased. It was found that the binding strength of Cu and ZnO was moderate and the active sites were well dispersed in the catalyst with copper molar fraction of 40%. The effects of hydrothermal conditions on the catalytic performance were investigated. The optimal hydrothermal conditions for the preparation of were Cu-ZnO catalyst as follows: temperature 130 ℃ and reaction time of 10 h. The conversion rate of ethyl acetate reached 94% under the conditions of reaction temperature of 220 ℃, hydrogen pressure of 3 MPa, molar ratio of hydrogen to ethyl acetate of 20, liquid hourly space velocity of 2.0 g ethyl acetate/(g catalyst·h). The conversion rate of ethyl acetate remained above 92% in the stability test of catalyst(300 h).
作者
鲁旖
吴浩飞
江志东
LU Yi;WU Haofei;JIANG Zhidong(School of Chemistry and Chemical Engineering,Shanghai Jiao Tong University,Shanghai 200240,China)
出处
《精细化工》
EI
CAS
CSCD
北大核心
2021年第5期988-993,共6页
Fine Chemicals
关键词
乙酸乙酯
乙醇
催化加氢
铜-氧化锌催化剂
水热法
纳米花自组装
催化技术
ethyl acetate
ethanol
catalytic hydrogenation
Cu-ZnO catalysts
hydrothermal synthesis
self-assembled nanoflowers
catalysis technology
