Active site isolation in bismuth-poisoned Pd/SiO2 catalysts for selective hydrogenation of furfural
Active site isolation in bismuth-poisoned Pd/SiO2 catalysts for selective hydrogenation of furfural
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DOI：
10.1016/j.apcata.2018.11.016
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发表时间：
2019-01-25
影响因子：
5.5
通讯作者：
Rebrov, Evgeny V.
中科院分区：
文献类型：
--
作者：
Cherkasov, Nikolay;Exposito, Antonio Jose;Rebrov, Evgeny V.
采用铋中毒法研究了糠醛加氢反应中钯催化剂活性中心的分离。在间歇式反应器中，在各种反应温度和压力下，在5wt%Pd/SiO2催化剂上氢化FA在水中的溶液。糠醇（FAL）是一种中间产物，其进一步加氢为四氢糠醇（TFAL）或环戊酮（CPA）和环戊醇（CPOL）。虽然施加高于30巴的氢气压力对氢化动力学几乎没有影响，但反应温度影响产物分布，并且主要产物从TFAL（在50 ℃下）变为FAL（100和150 ℃）。中毒的催化剂与Bi减少可用的活性位点的数量，但对翻转频率几乎没有影响，最有可能是因为没有电子效应的Bi对Pd纳米粒子。Bi中毒催化剂上的主要反应产物是FAL，没有FA低聚产物。在150 ℃的反应温度下，以57%的产率形成CPA。考虑到Bi优先毒化Pd的台阶位点，Pd和Pd-Bi催化剂之间的产物分布的比较以及合金Pd-Cu催化剂的文献数据表明，在Pd-Bi催化剂中观察到的活性位点隔离是增加FAL和CPA选择性和消除低聚物副产物的原因。
Active site isolation in furfural (FA) hydrogenation was studied by poisoning a Pd catalyst with bismuth. A solution of FA in water was hydrogenated over a 5 wt% Pd/SiO2 catalyst in a batch reactor at various reaction temperatures and pressures. Furfuryl alcohol (FAL) was an intermediate product which was further hydrogenated into tetrahydrofurfuryl alcohol (TFAL) or cyclopentanone (CPA) and cyclopentanol (CPOL). While application of hydrogen pressure above 30 bar had little effect on the hydrogenation kinetics, a reaction temperature affected product distribution and the main product changed from TFAL (at 50 degrees C) to FAL (100 and 150 degrees C). Poisoning the catalyst with Bi decreased the number of available active sites but had little effect on the turn-over frequencies, most likely because of the absence of electronic effects of Bi on Pd nanoparticles. The main reaction product over the Bi-poisoned catalyst was FAL with no FA oligomerisation products. At a reaction temperature of 150 degrees C, CPA was formed with a 57% yield. Considering that Bi preferentially poisons step sites of Pd, the comparison of the product distribution between the Pd and Pd-Bi catalyst as well as the literature data for the alloy Pd-Cu catalysts indicates that the active site isolation observed in the Pd-Bi catalysts is responsible for the increasing FAL and CPA selectivities and elimination of oligomer by-products.