Effect of hydration on the surface basicity and catalytic activity of Mg-rare earth mixed oxides for aldol condensation
来源期刊：Journal of Rare Earths2018年第4期
论文作者：Zheng Wang Guanzhong Lu Wangcheng Zhan
文章页码：359 - 366
摘 要：Magnesium and rare earth mixed oxides（Mg3 REOx（RE=La, Y. Ce）） were prepared and characterized by Xray diffraction（XRD）, N2 adsorption-desorption, infrared spectra and microcalorimetry of CO2. The results reveal that the Mg3 CeOx catalyst is present in the form of Mg-Ce-O solid solution,while the Mg3 LaOx and Mg3 YOx catalysts are probably rare earth oxides dispersed on MgO surface. As a result, among the calcined Mg3 REOx catalysts, the Mg3 CeOx catalyst presents the highest rate constant for acetone aldolization, which is well correlated to its more homogeneous distribution of basic sites. In contrary, the Mg3 YOx catalyst exhibit the lowest catalytic activity for acetone aldolization. Upon hydration pre-treatment, the basic properties on the surface of the Mg3 REOx catalysts were changed markedly. The Mg3 YOx catalyst after hydration treatment shows the highest amount of basic sites on catalyst surface, and then exhibits the highest activity among the hydrated Mg3 REOx catalysts. These results make it possible to fine-tune basic sites for acetone aldolization.
Zheng Wang1,2，Guanzhong Lu1，Wangcheng Zhan1
1. Key Laboratory for Advanced Materials and REsearch Institute of Industrial Catalysis,School of Chemistry and Molecular Engineering, East China University of Science and Technology
摘 要：Magnesium and rare earth mixed oxides（Mg3 REOx（RE=La, Y. Ce）） were prepared and characterized by Xray diffraction（XRD）, N2 adsorption-desorption, infrared spectra and microcalorimetry of CO2. The results reveal that the Mg3 CeOx catalyst is present in the form of Mg-Ce-O solid solution,while the Mg3 LaOx and Mg3 YOx catalysts are probably rare earth oxides dispersed on MgO surface. As a result, among the calcined Mg3 REOx catalysts, the Mg3 CeOx catalyst presents the highest rate constant for acetone aldolization, which is well correlated to its more homogeneous distribution of basic sites. In contrary, the Mg3 YOx catalyst exhibit the lowest catalytic activity for acetone aldolization. Upon hydration pre-treatment, the basic properties on the surface of the Mg3 REOx catalysts were changed markedly. The Mg3 YOx catalyst after hydration treatment shows the highest amount of basic sites on catalyst surface, and then exhibits the highest activity among the hydrated Mg3 REOx catalysts. These results make it possible to fine-tune basic sites for acetone aldolization.
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