Pd supported on ZnII-CrIII mixed oxide as a catalyst for one-step synthesis of methyl isobutyl ketone
Pd supported on ZnII-CrIII mixed oxide as a catalyst for one-step synthesis of methyl isobutyl ketone
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DOI：
10.1016/j.jcat.2008.04.025
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发表时间：
2008-07-01
影响因子：
7.3
通讯作者：
Kozhevnikov, Ivan V.
中科院分区：
文献类型：
--
作者：
Al-Wadaani, Fahd;Kozhevnikova, Elena F.;Kozhevnikov, Ivan V.
以Pd为载体的复合氧化物是一种高效的双功能催化剂，可用于丙酮和氢气在气相和液相中一步合成甲基异丁基酮(MIBK)。该反应包括丙酮在酸催化下缩合成均三甲基氧化物，然后加氢生成MIBK。二异丁基酮(DIBK)是这一过程中有用的副产品。以氢氧化锌和氢氧化铬为原料，采用共沉淀法制备了锌铬氧化物(锌/铬=20：1-1：30)。对锌铬氧化物的结构和酸性(即酸中心的性质、密度和强度)以及Pd在催化剂中的分散情况进行了全面的表征。对于连续气相法和间歇液相法，优选的催化剂配方均为0.3wt%Pd在具有Lewis酸位的非晶态锌(：R(1：1)氧化物(S-比表面积=132m(2)/g)上)，其NH3吸附热焓为-155kJ/mol。在丙酮转化率为38-40%的条件下，两种工艺均可生产MIBK，选择性为70-78%，MIBK+DIBK的总选择性为90%。有证据表明，甲苯基氧化物加氢生成MIBK是气相过程中的限速步骤。(C)2008 Elsevier Inc.保留所有权利。
Pd metal supported on Zn-II-Cr-III mixed oxide is an efficient bifunctional catalyst for the one-step synthesis of methyl isobutyl ketone (MIBK) from acetone and H-2 in the gas and liquid phases. The reaction involves acid-catalysed condensation of acetone to mesityl oxide, followed by its hydrogenation to MIBK. Diisobutyl ketone (DIBK) is a useful byproduct in this process. Zn-Cr oxides (Zn/Cr = 20: 1-1:30) are prepared by coprecipitation of Zn-II and Cr-III hydroxides. The texture and acid properties (i.e., the nature, density, and strength of acid sites) of Zn-Cr oxides, as well as the Pd dispersion in the catalysts, are thoroughly characterised. For both the continuous gas-phase process and the batch liquidphase process, the preferred catalyst formulation is 0.3 wt% Pd on the amorphous Zn-(:r (1:1) oxide (S-BET = 132 m(2)/g) having Lewis acid sites (1.2 mmol/g density) with an enthalpy of NH3 adsorption of -155 kJ/mol. Both processes produce MIBK with a selectivity of 70-78% and 90% MIBK + DIBK total selectivity at 38-40% acetone conversion. Evidence is provided that hydrogenation of mesityl oxide to MIBK is the rate-limiting step in the gas-phase process. (c) 2008 Elsevier Inc. All rights reserved.