本文關鍵詞： 負載型納米金催化劑 活性位點 尺寸效應 CO氧化 水煤汽轉換反應　出處：《山東大學》2016年碩士論文　論文類型：學位論文

【摘要】：在本論文中,我們選用Ce02納米棒作為載體,并選用了合適的負載方法制備了一系列納米金催化劑,具體研究內(nèi)容如下：一、不同尺寸金物種(原子、團簇、顆粒)催化CO氧化活性的研究在棒狀納米二氧化鈰載體表面通過膠體沉積法,沉積沉淀法以及還原氣氛的處理分別制備出含有金原子/團簇/顆粒的負載型金催化劑,通過球差校正的HADDF-STEM直接觀察到不同尺寸的金物種,并使用in-situ XAFS、in-situ DRIFTS等一系列原位表征手段探究了反應條件下金的價態(tài)和配位結構,得到了反應過程中不同金物種對CO的吸附強度,從而說明了金屬態(tài)的金顆粒具有最好CO氧化催化活性。二、不同尺寸金物種(團簇、顆粒)對水汽轉換反應活性的研究同樣采用膠體沉積法和沉積沉淀法分別制備兩種尺寸不同的負載型金催化劑,通過XAFS、H2-TPR、XPS等一系列表征手段對催化劑進行表征。我們發(fā)現(xiàn)經(jīng)過水汽轉換反應,沉積沉淀法制備的催化劑中的金原子被還原成金團簇,這說明水汽轉換反應氣氛具有還原性。由于二氧化鈰載體對Au具有很強的穩(wěn)定作用,因此反應過程中,對于沉積沉淀法制備的催化劑即使金物種被還原,催化劑仍然具有較小的尺寸以及很好的催化性能。這說明對于水汽轉換反應而言,催化活性的來源是小尺寸的金物種。三、不同煅燒溫度載體對催化活性影響的研究對納米棒狀二氧化鈰載體進行不同溫度的煅燒,通過沉積沉淀法對不同溫度煅燒系列載體進行負載,并使用XRD、H2-TPR、O2-TPD、XPS、Raman光譜和DRIFTS等對催化劑進行了表征。制備得到的催化劑在CO氧化中表現(xiàn)出了較大的活性差異,其中載體經(jīng)過500℃煅燒載金催化劑的催化活性最好,這可能與此條件下處理的載體的特殊表面結構相關。
[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，

本文編號：1443185