铈改性甲醇合成铜基催化剂的制备及其性能

doi:10.3969/j.issn.0438-1157.2014.07.038

摘要/Abstract

摘要： 采用反加共沉淀法，以硝酸铜、硝酸锌、硝酸铝溶液为原料，碳酸钠溶液为沉淀剂，硝酸铈为助剂，制备了铈（Ce）改性的甲醇合成铜基催化剂（CuZnAlCe），并通过X射线衍射（XRD）、N₂等温吸附、热重-差热分析（TG-DTA）、扫描电子显微镜（SEM）、程序升温还原（TPR）等手段进行表征，采用微型固定床反应装置进行催化活性及稳定性评价，考察了Ce含量对CuZnAlCe催化剂结构和催化性能的影响。结果表明，Ce的引入可以改善催化剂活性中心的分散度，使催化剂比表面积增加，整体的结构变得更加松散，催化剂更容易被还原。随着Ce含量的增加，CO的转化率不断增大，当Ce含量为2%时CO转化率最大，可达47.6%。但Ce含量过量时使催化剂还原温度升高，CO的转化率降低。此外，适当的Ce含量改性可以提高铜基催化剂的热稳定性。

关键词: 反加共沉淀法, 铈改性, 铜基催化剂, 甲醇合成

Abstract: Cerium modified Cu-based catalysts (CuZnAlCe) for methanol synthesis from syngas were prepared by anti-coprecipitation method with Na₂CO₃ solution as a precipitant, Cu(NO₃)₂, Zn(NO₃)₂ and Al₂(NO₃)₃ solution as raw materials. The structure and morphology of CuZnAlCe were studied by X-ray diffraction, thermal gravimetry-differential thermal analysis, N₂ adsorption-desorption measurement, scanning electron microscopy, and temperature programmed reduction. The catalytic activities of the prepared catalysts for methanol synthesis were evaluated on micro fixed-bed reaction system. It showed that the addition of Ce improved the dispersion of active sites and provided a high surface area, which play an important role in the stability and activity of CuZnAlCe. The CO conversion reached an optimum value to 47.6% over the Ce modified Cu-based catalyst at the Cu/Ce molar ratio of 1:0.02, while the catalytic activity and stability decreased when the loading of Ce was excessive. Proper loadings of Ce could improve the thermal stability of Cu-based catalysts.

Key words: anti-coprecipitation, Ce modification, Cu-based catalysts, methanol synthesis

中图分类号:

O643

胡菊, 潘亚林, 黎汉生, 吴芹, 王金福. 铈改性甲醇合成铜基催化剂的制备及其性能[J]. 化工学报, 2014, 65(7): 2770-2775.

HU Ju, PAN Yalin, LI Hansheng, WU Qin, WANG Jinfu. Preparation and properties of cerium modified Cu-based catalysts for methanol synthesis[J]. CIESC Journal, 2014, 65(7): 2770-2775.

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