Construction of mesoporous Cu/ZrO2-Al2O3 as a ternary catalyst for efficient synthesis of γ-valerolactone from levulinic acid at low temperature
Construction of mesoporous Cu/ZrO2-Al2O3 as a ternary catalyst for efficient synthesis of γ-valerolactone from levulinic acid at low temperature
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介孔Cu/ZrO2-Al2O3三元催化剂的构建用于乙酰丙酸低温高效合成戊内酯
DOI：
10.1016/j.jcat.2019.10.031
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发表时间：
2020-01-01
影响因子：
7.3
通讯作者：
Dong, Wen-Sheng
中科院分区：
文献类型：
--
作者：
Li, Jifan;Li, Mengjie;Dong, Wen-Sheng
构建了一种含有金属Cu、ZrO 2衍生的氧缺陷和酸性Al 2 O3的三元贱金属催化剂，用于乙酰丙酸加氢合成γ-戊内酯。通过微调这三种活性组分的比例，获得了优异的催化性能。优化后的Cu/Zr-Al-3催化剂具有上级催化活性，质量活性高达220.5 mmol GVL·h（-1）·g（-1）surf. Cu在130摄氏度下，其比Cu/Al高近8倍，比Cu/Zr高9倍。更重要的是，Cu/Zr-Al-3还具有良好的循环稳定性，使其成为一种潜在的工业应用催化剂。ZrO 2的存在减弱了Cu-Al_2 O_3相互作用，形成了Zr-O-Al相互作用，并以Al_2O_3-ZrO_2固溶体的形式存在，促进了CuO物种的还原，从而促进了催化剂表面CuO活性位的形成。XPS和NH3程序升温脱附结果也证明了优化的三元催化剂上存在大量的氧空位和酸中心。乙酰丙酸可以通过其羧基或羰基强烈地吸附在氧空位上，然后容易地被解离在CuO位点上的活性H原子连接以形成活性中间体，而呈现在三元催化剂表面上的酸位点促进吸附的活性中间体随后的脱水和分子内酯化，从而促进c-戊内酯的形成。乙酰丙酸在氧空位上的吸附还通过形成可溶性Cu金属羧酸盐络合物避免了活性Cu金属的浸出，从而使优化的三元催化剂具有突出的循环稳定性。Cu/Zr-Al-3催化剂具有良好的上级催化活性和循环稳定性，主要是由于这些活性中心的协同作用。(C)2019爱思唯尔公司All rights reserved.
A ternary base metal catalyst, which contained metallic Cu, oxygen deficiencies derived from ZrO2, and acidic Al2O3, was constructed for the efficient synthesis of gamma-valerolactone by levulinic acid hydrogenation under mild conditions. Excellent catalytic performance was obtained by fine tuning the proportion of these three active components. The optimized Cu/Zr-Al-3 catalyst achieved superior catalytic activity with a high mass activity of 220.5 mmol GVL.h(-1).g(-1) surf. Cu at 130 degrees C, which was nearly eight times higher than Cu/Al and nine times higher than Cu/Zr. More importantly, Cu/Zr-Al-3 also possessed excellent recycling stability, making it as a potential catalyst for industrial applications. The presence of ZrO2 in the ternary catalysts weakened the Cu-Al2O3 interaction and formed Zr-O-Al interaction in the form of Al2O3-ZrO2 solid solution, which facilitated the reduction of CuO species and in turn enhanced the formation of more CuO active sites on the catalyst surface. The existence of a large number of oxygen vacancies and acid sites on the optimized ternary catalysts was also demonstrated by XPS and NH3 temperature-programmed desorption results. Levulinic acid can be adsorbed strongly on oxygen vacancies by its carboxylic or carbonyl groups and then readily attached by active H atoms dissociated on CuO sites to form active intermediates, while the acid sites presented on the ternary catalyst surface promote subsequent dehydration and intramolecular esterification of adsorbed active intermediates and consequently facilitate the formation of c-valerolactone. The adsorption of levulinic acid onto oxygen vacancies also avoided the leaching of active Cu metal via the formation of soluble Cu metal carboxylate complexes, resulting in outstanding recycling stability for the optimized ternary catalysts. The intimate synergies of these ternary active sites mainly accounted for the superior catalytic activity and excellent recycling stability of the Cu/Zr-Al-3 catalyst. (C) 2019 Elsevier Inc. All rights reserved.