An insight into the Meerwein–Ponndorf–Verley reduction of α,β-unsaturated carbonyl compounds: Tuning the acid–base properties of modified zirconia catalysts
An insight into the Meerwein–Ponndorf–Verley reduction of α,β-unsaturated carbonyl compounds: Tuning the acid–base properties of modified zirconia catalysts
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DOI：
10.1016/j.jcat.2009.09.005
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发表时间：
2009-11
影响因子：
7.3
通讯作者：
F. Urbano;M. Aramendía;A. Marinas;J. Marinas
中科院分区：
文献类型：
--
作者：
F. Urbano;M. Aramendía;A. Marinas;J. Marinas
制备了一系列由纯ZrO 2和掺杂硼或碱土金属的ZrO 2组成的催化剂，并将其用于肉桂醛与异丙醇的Meerwein-Ponndorf-Verley还原反应，在此反应中，它们表现出中等活性和对肉桂醇的高选择性（高达98%）.发现催化剂制备过程及其改性（即，用硼或碱土金属掺杂）延迟结晶并增加催化剂表面上存在的羟基的数量，从而增加其催化活性。用吡啶和二氧化碳化学吸附法分别测定了催化剂的表面酸碱性质。在所研究的反应中，最活跃的网站似乎质子（布朗斯台德）酸网站的中高强度形成的ZrO 2与硼的改性，然而，由此获得的增加的活性是伴随着对肉桂醇的选择性损失。用碱土金属改性ZrO 2提高了其碱性，从而降低了其催化活性，提高了其对不饱和醇的选择性。
A series of catalysts consisting of ZrO2in pure form or modified by doping with boron or an alkaline-earth metal to enhance their acid and basic properties, respectively, were prepared and used in the Meerwein–Ponndorf–Verley reduction of cinnamaldehyde with 2-propanol, where they exhibited moderate activity and a high selectivity (up to 98%) towards cinnamyl alcohol. The catalyst preparation procedure and its modification (viz. doping with boron or an alkaline-earth metal) were found to delay crystallization and increase the number of hydroxyl groups present on the catalyst surface, and hence its catalytic activity. The surface acid and basic properties of the catalysts were determined by pyridine and carbon dioxide chemisorption, respectively. The most active sites in the studied reaction are seemingly proton (Bronsted) acid sites of medium–high strength formed by modification of the ZrO2with boron; however, the increased activity thus obtained is accompanied by a loss of selectivity towards cinnamyl alcohol. Modifying ZrO2with an alkaline-earth metal enhances its basicity, thereby reducing its catalytic activity and increasing its selectivity for the unsaturated alcohol.