Covalent Amide-based Framework with Pd Nanoparticles Catalytic Carbon Dioxide Hydrogenation to Formic Acid

Covalent Amide-based Framework with Pd Nanoparticles Catalytic Carbon Dioxide Hydrogenation to Formic Aci

Ir-CeO2催化剂上CO选择氧化反应的研究

质子交换膜燃料电池的电极催化剂很容易被氢源中微量的CO毒化而显著降低其催化效率。CO选择氧化是消除富氢气氛中微量CO最简单、最有效的方法。本论文选择CeO2担载的Ir为CO选择氧化催化剂展开研究。 系统研究了制备方法、载体、金属担载量、预处理条件、氧气浓度、原料气体组成对Ir-CeO2催化剂上CO选择氧化反应活性和选择性的影响。发现沉积沉淀法制备的Ir-CeO2催化剂在CO选择氧化反应中也表现出了很好的催化活性。 氯离子存在会显著降低Ir-CeO2催化剂的反应活性。研究发现：氯离子的存在不仅会抑制CO在Ir上的吸附与活化，而且更重要的是使CeO2失去了活化氧的能力，从而严重降低了其CO氧化的催化活性。而且，氯离子的存在还会抑制表面碳酸盐的生成，从而失去了通过碳酸盐的分解而实现CO转化的反应途径。 采用氧化还原-共沉淀法制备出了高活性、高选择性的Ir-in-CeO2催化剂，详细研究了制备参数对反应活性的影响。发现Ir对CeO2的活化程度直接决定了其催化性能，只有被Ir适度活化的CeO2才具有最好的催化性能。当Ir-in-CeO2催化剂用于CO选择氧化反应时，CO氧化在被活化的CeO2上进行，由于暴露在表面Ir物种很少，抑制了H2的解离和氧化，从而使该催化剂能够在较宽的温度范围内保持高的CO2选择性

逆水气变换反应中K对Pt/mullite催化剂促进作用的研究

Promoting Role of Potassium in the Reverse Water Gas Shift Reaction on Pt/mullite Catalys

Influence of pre-treatment temperature on catalytic performance of rutile TiO2 supported ruthenium catalyst in CO2 methanation

Influence of pre-treatment temperature on catalytic performance of rutile TiO2 supported ruthenium catalyst in CO2 methanatio

Theoretical i nsights into s upported metal catalysts for highly s elective CO 2 -to -CO conversion

Theoretical i nsights into s upported metal catalysts for highly s elective CO 2 -to -CO conversio

Pd Supported on Nitrogen Doped Carbon as an Efficient Bifunctional Catalyst for Formate-based Carbon-neutral Hydrogen Storage System

Pd Supported on Nitrogen Doped Carbon as an Efficient Bifunctional Catalyst for Formate-based Carbon-neutral Hydrogen Storage Syste

TiO2促进的Ir/Al2O3催化剂用于氧化亚氮直接分解

Introduction Doping transition metal oxides or alkali and alkaline earth metal oxides into noble metal based catalysts is an extensively used method to adjust the physiochemical properties of the catalysts and improve the catalytic activities [1]. However, TiO2 doped Al2O3 catalysts have been scarcely investigated, especially for the catalytic decomposition of N2O. In this work, an obvious activity improvement on direct N2O decomposition has been obtained on Ir/AlTix catalysts, and possible reasons have been explored with different characterization techniques. The high dispersity of Ir particles and special textural features of the catalysts have been assumed to closely correlate with the high activities. Results and discussion 5 wt % Ir/AlTix catalysts with different atomic ratios of Ti/Al (x) were prepared with an impregnation method. Great improvement on the catalytic activities of direct N2O decomposition has been observed on the TiO2 doped catalysts (Fig. 1), which is obviously varied with the Ti/Al ratio. The highest activity was obtained on the Ir/AlTi1 catalyst, completely decomposing N2O at 350 oC, a fairly low temperature under the same test conditions. The reasons for the activity improvement have been detailedly investigated. The Ir particle sizes were found less than 3 nm and abundantly exposed on the surface of the doped catalyst (Fig. 2a), while the majority of Ir on the single oxide based catalysts were agglomerated into larger particles (Fig. 2b and 2c). The high dispersity of Ir particles may be responsible for the activity improvement of the TiO2 doped catalysts. More interestingly, SEM images revealed that rough surfaces with the fluffy structures were formed on the doped catalysts (Fig. 2d), in contrast, the surfaces of the single TiO2 or Al2O3 catalysts remained smooth and clean. These surface irregularities probably acted as obstacles to the immigration of Ir during the calcination process, finally resulting in the high dispersity of Ir particles as well as the high catalytic activities. Further studies on the role of TiO2 are still in progress. Fig. 1. N2O activities of TiO2 doped Ir/Al2O3 catalysts Fig. 2. TEM and SEM images Conclusions TiO2 doped Ir/Al2O3 catalysts greatly promoted the catalytic activity of direct N2O decomposition, probably due to the high dispersity of Ir particles induced by the irregular surfaces. References [1] Junhua Li, Yongqing Zhu, Rui Ke, Jiming Hao, Applied Catalysis B: Environmental 80 (2008) 202–213.Introduction Doping transition metal oxides or alkali and alkaline earth metal oxides into noble metal based catalysts is an extensively used method to adjust the physiochemical properties of the catalysts and improve the catalytic activities [1]. However, TiO2 doped Al2O3 catalysts have been scarcely investigated, especially for the catalytic decomposition of N2O. In this work, an obvious activity improvement on direct N2O decomposition has been obtained on Ir/AlTix catalysts, and possible reasons have been explored with different characterization techniques. The high dispersity of Ir particles and special textural features of the catalysts have been assumed to closely correlate with the high activities. Results and discussion 5 wt % Ir/AlTix catalysts with different atomic ratios of Ti/Al (x) were prepared with an impregnation method. Great improvement on the catalytic activities of direct N2O decomposition has been observed on the TiO2 doped catalysts (Fig. 1), which is obviously varied with the Ti/Al ratio. The highest activity was obtained on the Ir/AlTi1 catalyst, completely decomposing N2O at 350 oC, a fairly low temperature under the same test conditions. The reasons for the activity improvement have been detailedly investigated. The Ir particle sizes were found less than 3 nm and abundantly exposed on the surface of the doped catalyst (Fig. 2a), while the majority of Ir on the single oxide based catalysts were agglomerated into larger particles (Fig. 2b and 2c). The high dispersity of Ir particles may be responsible for the activity improvement of the TiO2 doped catalysts. More interestingly, SEM images revealed that rough surfaces with the fluffy structures were formed on the doped catalysts (Fig. 2d), in contrast, the surfaces of the single TiO2 or Al2O3 catalysts remained smooth and clean. These surface irregularities probably acted as obstacles to the immigration of Ir during the calcination process, finally resulting in the high dispersity of Ir particles as well as the high catalytic activities. Further studies on the role of TiO2 are still in progress. Fig. 1. N2O activities of TiO2 doped Ir/Al2O3 catalysts Fig. 2. TEM and SEM images Conclusions TiO2 doped Ir/Al2O3 catalysts greatly promoted the catalytic activity of direct N2O decomposition, probably due to the high dispersity of Ir particles induced by the irregular surfaces. References [1] Junhua Li, Yongqing Zhu, Rui Ke, Jiming Hao, Applied Catalysis B: Environmental 80 (2008) 202–213

温和条件下水合肼催化分解制氢研究进展

水合肼（N2H4·H2O）的氢质量分数高达8.0%，完全分解时副产物仅为N2，且在温和条件下物理化学性质较为稳定，因此可以作为一种理想的移动氢源，在一些特殊场合为燃料电池提供氢气。本文概述了温和条件下水合肼分解制氢反应所使用的催化体系，具体包括金属纳米粒子、复合氧化物及负载型催化剂。简要介绍了肼分解过程的机理，并分析了影响水合肼分解制氢选择性的因素，包括催化剂中活性金属的特性、反应条件及助剂的性质对催化剂选择性的影响。总结了现阶段水合肼分解制氢催化剂的优缺点，为进一步开发高效、高选择性的水合肼分解制氢催化剂提供借鉴，并为涉及N-H键及N-N键断裂的其他反应催化剂设计提供参考