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Effects of Support on the Formation and Activity of Gold Catalysts for Ethanol Conversion to Butanol
Petroleum Chemistry ( IF 1.4 ) Pub Date : 2021-06-18 , DOI: 10.1134/s0965544121050145
S. A. Nikolaev , A. V. Chistyakov , P. A. Chistyakova , D. I. Ezzhelenko , E. Yu. Liberman , T. V. Konkova , M. V. Tsodikov

Abstract

Using a combination of physicochemical methods, such as TEM, SEM, EDS, XPS, NH3–TPD, and N2 adsorption, the study investigates the structure of a number of supports (Al2O3, SiO2, TiO2, ZrO2, and C) and of Au/support catalyst samples (Au = 0.5%). The concentration of highly active 2–4 nm gold particles in Au catalysts is influenced by the support’s texture; this concentration increases in the following order: Au/TiO2 < Au/ZrO2 < Au/C < Au/SiO2 << Au/Al2O3. The acidity of Au catalysts is influenced by the support’s nature; this acidity decreases in the following order: Al2O3 > TiO2 > ZrO2 > SiO2 >> Au/C. At 275°C, a carbon support is inactive in ethanol conversion to butanol. In the presence of oxide supports, the target reaction occurs at a relatively low rate by a bimolecular condensation mechanism. Over Au/Al2O3, Au/SiO2, Au/TiO2, or Au/ZrO2, the reaction occurs more rapidly by an aldol condensation mechanism. At an ethanol conversion of 14–18%, the butanol selectivity increases in the following order: Au/C(0) << Au/SiO2 (0.4%) < Au/ZrO2 (1.5%) < Au/TiO2 (2%) << Au/Al2O3 (78%). The high efficiency of Au/Al2O3 stems from the high density of the Aln+–O2– sites located on the support’s surface, and of the coordination-unsaturated Au0(KH) atoms located on the surface of 2–4 nm gold particles.



中文翻译:

载体对乙醇转化为丁醇的金催化剂的形成和活性的影响

摘要

该研究结合使用 TEM、SEM、EDS、XPS、NH 3 –TPD 和 N 2吸附等物理化学方法,研究了多种载体(Al 2 O 3、SiO 2、TiO 2、ZrO图 2和 C) 和 Au/载体催化剂样品 (Au = 0.5%)。Au 催化剂中高活性 2-4 nm 金颗粒的浓度受载体质地的影响;该浓度按以下顺序增加:Au/TiO 2 < Au/ZrO 2 < Au/C < Au/SiO 2 << Au/Al 2 O 3. Au催化剂的酸度受载体性质的影响;这种酸度按以下顺序降低:Al 2 O 3 > TiO 2 > ZrO 2 > SiO 2 >> Au/C。在 275°C 时,碳载体在乙醇转化为丁醇的过程中是无活性的。在氧化物载体的存在下,目标反应通过双分子缩合机制以相对低的速率发生。在 Au/Al 2 O 3、Au/SiO 2、Au/TiO 2或 Au/ZrO 2 上,通过醇醛缩合反应发生得更快机制。在乙醇转化率为 14-18% 时,丁醇选择性按以下顺序增加:Au/C(0) << Au/SiO 2 (0.4%) < Au/ZrO 2 (1.5%) < Au/TiO 2 ( 2%) << Au/Al 2 O 3 (78%)。Au/Al 2 O 3的高效率源于位于载体表面的高密度 Al n + –O 2–位点,以及位于2–表面的配位不饱和 Au 0 (KH) 原子4 nm 金颗粒。

更新日期:2021-06-21
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