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The effect of surface chemistry on the performances of Pd-based catalysts supported on activated carbons
Catalysis Science & Technology ( IF 4.4 ) Pub Date : 2017-08-14 00:00:00 , DOI: 10.1039/c7cy01005b A. Lazzarini 1, 2, 3, 4, 5 , R. Pellegrini 5, 6, 7 , A. Piovano 8, 9, 10 , S. Rudić 11, 12, 13, 14 , C. Castan-Guerrero 5, 15, 16, 17 , P. Torelli 5, 15, 16, 17 , M. R. Chierotti 1, 2, 3, 4, 5 , R. Gobetto 1, 2, 3, 4, 5 , C. Lamberti 1, 2, 3, 4, 5 , E. Groppo 1, 2, 3, 4, 5
Catalysis Science & Technology ( IF 4.4 ) Pub Date : 2017-08-14 00:00:00 , DOI: 10.1039/c7cy01005b A. Lazzarini 1, 2, 3, 4, 5 , R. Pellegrini 5, 6, 7 , A. Piovano 8, 9, 10 , S. Rudić 11, 12, 13, 14 , C. Castan-Guerrero 5, 15, 16, 17 , P. Torelli 5, 15, 16, 17 , M. R. Chierotti 1, 2, 3, 4, 5 , R. Gobetto 1, 2, 3, 4, 5 , C. Lamberti 1, 2, 3, 4, 5 , E. Groppo 1, 2, 3, 4, 5
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In this work we investigated in detail the effects of nitric acid on the surface chemistry of two carbons, activated by steam and by phosphoric acid, meant to identify the nature and the concentration of the oxidized surface species. To this aim, the oxidized carbons were characterized by means of a large number of complementary techniques, including micro-Raman spectroscopy, N2 physisorption, Boehm titration method, 13C solid state nuclear magnetic resonance, X-ray photoelectron spectroscopy, diffuse reflectance infrared and inelastic neutron scattering spectroscopy. Carboxylic and carboxylate groups are mainly formed, the latter stabilized by the extended conjugation of the π electrons and being more abundant on small and irregular graphitic platelets. We demonstrated that the presence of oxygen-containing groups acts against the palladium dispersion and causes the appearance of an appreciable induction time in hydrogenation reactions. The carbon with more oxygenated surface species (and in particular more carboxylate groups) must be chosen in the hydrogenation of polar substrates, while it is detrimental to the hydrogenation of nonpolar substrates.
中文翻译：
表面化学对活性炭负载的Pd基催化剂性能的影响
在这项工作中，我们详细研究了硝酸对被蒸汽和磷酸活化的两个碳的表面化学的影响，旨在确定被氧化表面物种的性质和浓度。为此，通过大量辅助技术对氧化碳进行了表征，包括微拉曼光谱法，N 2物理吸附，Boehm滴定法，13C固态核磁共振，X射线光电子能谱，漫反射红外和非弹性中子散射光谱。主要形成羧酸基和羧酸基，后者通过π电子的扩展共轭而稳定，并且在小的和不规则的石墨血小板上含量更高。我们证明了含氧基团的存在会影响钯的分散并在氢化反应中引起明显的诱导时间。在极性底物的氢化中必须选择具有更多被氧化的表面物种（特别是更多的羧酸根基团）的碳，同时不利于非极性底物的氢化。
更新日期：2017-09-19
中文翻译：
表面化学对活性炭负载的Pd基催化剂性能的影响
在这项工作中，我们详细研究了硝酸对被蒸汽和磷酸活化的两个碳的表面化学的影响，旨在确定被氧化表面物种的性质和浓度。为此，通过大量辅助技术对氧化碳进行了表征，包括微拉曼光谱法，N 2物理吸附，Boehm滴定法，13C固态核磁共振，X射线光电子能谱，漫反射红外和非弹性中子散射光谱。主要形成羧酸基和羧酸基，后者通过π电子的扩展共轭而稳定，并且在小的和不规则的石墨血小板上含量更高。我们证明了含氧基团的存在会影响钯的分散并在氢化反应中引起明显的诱导时间。在极性底物的氢化中必须选择具有更多被氧化的表面物种（特别是更多的羧酸根基团）的碳，同时不利于非极性底物的氢化。
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