Quantitative 1,10-Phenanthroline Catalyst-Poisoning Kinetic Studies of Rh(0) Nanoparticle and Rh4 Cluster Benzene Hydrogenation Catalysts: Estimates of the Poison Kassociation Binding Constants, of the Equivalents of Poison Bound and of the Number of Catalytically Active Sites for Each Catalyst
Quantitative 1,10-Phenanthroline Catalyst-Poisoning Kinetic Studies of Rh(0) Nanoparticle and Rh4 Cluster Benzene Hydrogenation Catalysts: Estimates of the Poison Kassociation Binding Constants, of the Equivalents of Poison Bound and of the Number of Catalytically Active Sites for Each Catalyst
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DOI：
10.1021/cs300330c
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发表时间：
2012-09-01
期刊：
影响因子：
12.9
通讯作者：
Finke, Richard G.
中科院分区：
文献类型：
--
作者：
Bayram, Ercan;Finke, Richard G.
定量催化剂中毒研究具有根本的兴趣和重要性，因为（a）需要知道真实活性位点的数量以计算真实的转换频率;（产品摩尔数）/（实际活性位点的摩尔数）（时间），并且因为（B）定量催化剂中毒被证明是关键，所以在区分单一金属（M-1）的过程中需要数据片段，小金属簇（例如，M-4）或金属纳米颗粒（M-n）催化。在后一点的证据中，使用1，10-菲咯啉作为毒物的定量催化剂中毒实验被证明在最近鉴定Rh-4亚纳米簇作为以[RhCp*Cl-2]开始的系统中的真正苯加氢催化剂中是至关重要的（2）。（Cp*：（eta（5）-C-5（CH 3）（5）（Bayram等人，J. Am. 2011，133，18889）。然而，尽管这些定量中毒研究取得了成功，但有关此类中毒研究的五个问题仍未得到解答，本文提出并解决了这些问题。此外，本文对Rh（0）纳米颗粒和Rh-4亚纳米苯加氢催化剂的1，10-菲咯啉中毒的分析分别产生了强结合和弱结合毒物的动力学模型。还提供了毒物结合常数、完全毒化每种催化剂所需的当量数和每种催化剂上活性位点数的定量估计。弱结合毒物动力学模型，然后示出有直接的适用性，通过其应用到文献CS2定量中毒数据氨硼烷脱氢偶联开始与[Ru（COD）（cot）]（COD：环辛三烯和cot：环辛三烯）预催化剂分析现存的文献数据。然后在结论部分总结了结果的意义。
Quantitative catalyst poisoning studies are of fundamental interest and importance because (a) knowledge of the number of true active sites is required for calculation of the true turnover frequency = (moles of product)/(moles of actual active sites) (time), and because (b) quantitative catalyst poisoning is proving to be a key, required piece of data en route to distinguishing single metal (M-1), small metal cluster (e.g., M-4), or metal nanoparticle (M-n) catalysis. In evidence of the latter point, quantitative catalyst poisoning experiments using 1,10-phenanthroline as the poison proved to be crucial in the recent identification of Rh-4 subnanometer clusters as the true benzene hydrogenation catalyst in a system beginning with [RhCp*Cl-2](2) (Cp*: (eta(5)-C-5(CH3)(5))) at 100 degrees C and 50 atm initial H-2 pressure (Bayram et al. J. Am. Chem. Soc. 2011, 133, 18889). However and despite the success of those quantitative poisoning studies, five questions about such poisoning studies remained unanswered, questions posed and then addressed herein. In addition, the analysis herein of the 1,10-phenanthroline poisoning of both Rh(0) nanoparticle and Rh-4 subnanometer benzene hydrogenation catalysts results in kinetic models for, respectively, strong-binding and weak-binding poisons. Also provided are quantitiative estimates of the poison binding constants, of the number of equivalents required to completely poison each catalyst, and of the number of active sites on each catalyst. The weak-binding poison kinetic model is then shown to have immediate applicability toward analyzing extant literature data via its application to literature CS2 quantitative poisoning data for ammonia-borane dehydrocoupling beginning with a [Ru(cod)(cot)] (cod: cyclooctadiene and cot: cyclooctatriene) precatalyst. The significance of the results is then summarized in a Conclusions section.