负载型二氧化铈纳米金催化剂的制备及性能研究

发布时间：2018-01-19 07:19

  本文关键词： 负载型纳米金催化剂 活性位点 尺寸效应 CO氧化 水煤汽转换反应　出处：《山东大学》2016年硕士论文　论文类型：学位论文

【摘要】：在本论文中,我们选用Ce02纳米棒作为载体,并选用了合适的负载方法制备了一系列纳米金催化剂,具体研究内容如下：一、不同尺寸金物种(原子、团簇、颗粒)催化CO氧化活性的研究在棒状纳米二氧化铈载体表面通过胶体沉积法,沉积沉淀法以及还原气氛的处理分别制备出含有金原子/团簇/颗粒的负载型金催化剂,通过球差校正的HADDF-STEM直接观察到不同尺寸的金物种,并使用in-situ XAFS、in-situ DRIFTS等一系列原位表征手段探究了反应条件下金的价态和配位结构,得到了反应过程中不同金物种对CO的吸附强度,从而说明了金属态的金颗粒具有最好CO氧化催化活性。二、不同尺寸金物种(团簇、颗粒)对水汽转换反应活性的研究同样采用胶体沉积法和沉积沉淀法分别制备两种尺寸不同的负载型金催化剂,通过XAFS、H2-TPR、XPS等一系列表征手段对催化剂进行表征。我们发现经过水汽转换反应,沉积沉淀法制备的催化剂中的金原子被还原成金团簇,这说明水汽转换反应气氛具有还原性。由于二氧化铈载体对Au具有很强的稳定作用,因此反应过程中,对于沉积沉淀法制备的催化剂即使金物种被还原,催化剂仍然具有较小的尺寸以及很好的催化性能。这说明对于水汽转换反应而言,催化活性的来源是小尺寸的金物种。三、不同煅烧温度载体对催化活性影响的研究对纳米棒状二氧化铈载体进行不同温度的煅烧,通过沉积沉淀法对不同温度煅烧系列载体进行负载,并使用XRD、H2-TPR、O2-TPD、XPS、Raman光谱和DRIFTS等对催化剂进行了表征。制备得到的催化剂在CO氧化中表现出了较大的活性差异,其中载体经过500℃煅烧载金催化剂的催化活性最好,这可能与此条件下处理的载体的特殊表面结构相关。
[Abstract]:In this paper, we selected Ce02 nanorods as the carrier, and selected the appropriate loading method to prepare a series of nanocrystalline gold catalysts. The specific research contents are as follows: first, different sizes of gold species (atoms). Study on the Catalytic activity of Catalytic CO Oxidation on the Surface of Rod Nano-Cerium oxide by Colloidal deposition. The supported gold catalysts containing gold atoms / clusters / particles were prepared by deposition method and reduction atmosphere respectively. Different sizes of gold species were observed directly by spherical aberration corrected HADDF-STEM. A series of in-situ characterization methods such as in-situ XAFSF-in-situ DRIFTS were used to investigate the valence state and coordination structure of gold under reaction conditions. The adsorption intensity of CO by different gold species in the reaction process was obtained, which indicated that the gold particles in the metal state had the best catalytic activity for CO oxidation. Secondly, the gold species (clusters) with different sizes were obtained. In the same way, two kinds of supported gold catalysts with different sizes were prepared by colloid deposition method and deposition precipitation method, respectively, and the two kinds of supported gold catalysts were prepared by XAFSX H2-TPR. A series of characterization methods such as XPS were used to characterize the catalysts. We found that the gold atoms in the catalysts prepared by deposition precipitation were reduced to gold clusters after the water vapor conversion reaction. This indicates that the atmosphere of water vapor conversion reaction is reductive. Because the cerium oxide carrier has a strong stabilizing effect on au, the catalyst prepared by deposition and precipitation method is reduced even for gold species during the reaction. The catalyst still has small size and good catalytic performance, which indicates that the source of catalytic activity for water vapor conversion reaction is small gold species. 3. Study on the effect of different calcination temperature carrier on the catalytic activity the nanorod cerium oxide carrier was calcined at different temperatures. The carrier was loaded by deposition precipitation method and XRD was used. The catalysts were characterized by the Raman spectra of H2-TPRO2-TPDO2-TPDOXPSN and DRIFTS, etc. The prepared catalysts showed great difference in activity in CO oxidation. The catalyst with gold carrier calcined at 500 鈩，

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