There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Jenny Schneider,*,† Masaya Matsuoka,‡ Masato Takeuchi,‡ Jinlong Zhang, Yu Horiuchi,‡ Masakazu Anpo,‡ and Detlef W. Bahnemann*,† †Institut fur Technische Chemie, Leibniz Universitaẗ Hannover, Callinstrasse 3, D-30167 Hannover, Germany ‡Faculty of Engineering, Osaka Prefecture University, 1 Gakuen-cho, Sakai Osaka 599-8531, Japan Key Lab for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237, China

Understanding TiO2 photocatalysis: mechanisms and materials.

Metal–organic frameworks (MOFs), also known as porous coordination polymers (PCPs), synthesized by assembling metal ions with organic ligands have recently emerged as a new class of crystalline porous materials. The amenability to design as well as fine-tunable and uniform pore structures makes them promising materials for a variety of applications. Controllable integration of MOFs and functional materials is leading to the creation of new multifunctional composites/hybrids, which exhibit new properties that are superior to those of the individual components through the collective behavior of the functional units. This is a rapidly developing interdisciplinary research area. This review provides an overview of the significant advances in the development of diverse MOF composites reported till now with special emphases on the synergistic effects and applications of the composites. The most widely used and successful strategies for composite synthesis are also presented.

Metal–organic framework composites

Metal-organic frameworks (MOFs) are an emerging class of porous materials with potential applications in gas storage, separations, catalysis, and chemical sensing. Despite numerous advantages, applications of many MOFs are ultimately limited by their stability under harsh conditions. Herein, the recent advances in the field of stable MOFs, covering the fundamental mechanisms of MOF stability, design, and synthesis of stable MOF architectures, and their latest applications are reviewed. First, key factors that affect MOF stability under certain chemical environments are introduced to guide the design of robust structures. This is followed by a short review of synthetic strategies of stable MOFs including modulated synthesis and postsynthetic modifications. Based on the fundamentals of MOF stability, stable MOFs are classified into two categories: high-valency metal-carboxylate frameworks and low-valency metal-azolate frameworks. Along this line, some representative stable MOFs are introduced, their structures are described, and their properties are briefly discussed. The expanded applications of stable MOFs in Lewis/Bronsted acid catalysis, redox catalysis, photocatalysis, electrocatalysis, gas storage, and sensing are highlighted. Overall, this review is expected to guide the design of stable MOFs by providing insights into existing structures, which could lead to the discovery and development of more advanced functional materials.

Stable Metal-Organic Frameworks: Design, Synthesis, and Applications.

Note: Times Cited: 875 Reference EPFL-ARTICLE-206025doi:10.1021/cr0501846View record in Web of Science URL: ://WOS:000249839900009 Record created on 2015-03-03, modified on 2017-05-12

Complex Hydrides for Hydrogen Storage

A three-way catalyst composition comprising a platinum group metal (PGM) component and an inorganic oxide, wherein the Infrared (IR) intensity ratio of bridge CO to atop CO on the PGM is less than 3:1 under standard CO adsorption procedure. The inorganic oxide may be doped with 10-30wt% of a dopant selected from La, Sr, Si, Ba, Y, r, Nd and Ce. Preferably, the PGM is Pd. Also described, is a catalyst composition comprising a platinum group metal (PGM) component and an inorganic oxide, wherein the Infrared (IR) intensity ratio of gem-dicarbonyl CO to atop CO on the PGM is less than 5:1 under standard CO adsorption procedure. Again, the inorganic oxide may be doped with 10-30wt% of a dopant selected from La, Sr, Si, Ba, Y, r, Nd and Ce. Preferably, the PGM is Rh. Catalyst articles for treating exhaust gas comprising a substrate and one of the two catalyst compositions are also described. A catalyst article for treating exhaust gas, an emission treatment system and a method of treating an exhaust gas from an internal combustion engine, using the three-way catalyst, are also described.

Improved twc catalysts containing high dopant support

Operando spectroscopies (in situ Ce and W L3-edge X-ray absorption near-edge structure, ultraviolet–visible (UV–vis), and infrared (IR) spectroscopies, combined with online analysis of gas-phase products) were exploited to elucidate reduction/oxidation half-cycles in the selective catalytic reduction of NO with NH3 (NH3–SCR) over WO3-loaded CeO2. The Ce4+ species was reduced by NO + NH3 to yield N2 and Ce3+ species (reduction half-cycle), which was then reoxidized by O2 (oxidation half-cycle). The oxidation state of the W6+ species remained unchanged under redox conditions. IR and theoretical results indicated that the reduction half-cycle started with the reaction of W6+–OH and adjacent Ce4+–O with NO to afford Ce3+ species and gaseous HONO, which was converted to NO+ species on the catalyst. The NO+ species then reacted with NH3 to generate N2. 

Operando Spectroscopic Study of Reduction and Oxidation Half-Cycles in NH3–SCR over CeO2-Supported WO3

Sulfated zirconia (ZrS) has been widely used as an acid catalyst in industrial processes for the isomerization of n-alkanes. Despite the excellent catalytic properties of this material, its catalytically active structure has been hardly identified to date. In this study, we investigated the crystal structure and acid properties of crystalline Zr3SO9, which was reported 30 years ago by Kato et al. Zr3SO9 was a hexagonal-shaped plate consisting of a (101) plane of the tetragonal ZrO2 phase with S species uniformly dispersed in the form of SO42–. Zr3SO9 exhibits an outstanding catalytic activity for acid reactions, which is superior to those of typical acid catalysts. The introduction of H2O into Zr3SO9 altered the nature of the acid sites, and almost all Lewis acid sites (LAS) were transformed into Brønsted acid sites (BAS). Spectroscopic analyses and density functional theory calculations revealed that the Zr sites adjacent to SO42– functioned as a LAS, while the H2O coordinated to this Zr site acted as a BAS. Moreover, Pt-loaded Zr3SO9 demonstrated a stable catalytic activity in the isomerization of n-butane under continuous gas-flow conditions, which was significantly higher than that of Pt-loaded ZrS that is employed as an industrial catalyst for this reaction. 

Acid Catalysis over Crystalline Zr3SO9: Role of the Local Structure in Generating Acidity

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Multi-functionality of rhodium-loaded MOR zeolite: production of H2via the water gas shift reaction and its use in the formation of NH3

For the hydrogenation of a tertiary amide (N-acetylpiperidine), Lewis acidic support materials (Nb2O5 and MoOx/TiO2) increase the catalytic activity of Pt metal nanoparticles by a factor of >100. In situ infrared (IR) study shows that coordination of the C=O group of amide to surface Lewis acid sites weakens the C=O bond, and the activated amide undergoes hydrogen transfer from H species on Pt sites. Among 19 types of heterogeneous catalysts tested, Pt/Nb2O5 shows the highest catalytic activity. Pt/Nb2O5 is generally effective for the selective hydrogenation of various tertiary amides and ɛ-caprolactam to the corresponding amines under additive-free and solventless conditions and shows an order of higher turnover number (TON) than previously reported catalysts. Pt-MoOx/TiO2 is the secondary most effective and is reusable 10 times after the reaction.

Takashi Toyao

Papers

Improved twc catalysts containing high dopant support

Operando Spectroscopic Study of Reduction and Oxidation Half-Cycles in NH3–SCR over CeO2-Supported WO3

Acid Catalysis over Crystalline Zr3SO9: Role of the Local Structure in Generating Acidity

Multi-functionality of rhodium-loaded MOR zeolite: production of H2via the water gas shift reaction and its use in the formation of NH3

Lewis Acid‐Promoted Heterogeneous Platinum Catalysts for Hydrogenation of Amides to Amines.