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Heterogeneous catalyst

Dario Formenti, Francesco Ferretti, Florian Korbinian Scharnagl, Matthias Beller
The reduction of nitro compounds to the corresponding amines is one of the most utilized catalytic processes in the fine and bulk chemical industry. The latest development of catalysts with cheap metals like Fe, Co, Ni, and Cu has led to their tremendous achievements over the last years prompting their greater application as "standard" catalysts. In this review, we will comprehensively discuss the use of homogeneous and heterogeneous catalysts based on non-noble 3d-metals for the reduction of nitro compounds using various reductants...
December 5, 2018: Chemical Reviews
Cesar Plascencia, Larry A Curtiss, Cong Liu
Single-site heterogeneous catalysts (SSHC) have received increasing attention due to their well-defined active sites and potentially high specific activity. Detailed computational studies were carried out on a set of potential SSHC's i.e., silica supported metal ions, to investigate the reactivity of these catalysts with H2 as well as to evaluate the performance of density functional theory (DFT) methods in conjunction with triple-ζ quality basis sets (i.e., cc-pVTZ) on reaction energetics. The ions considered include 4d and 5d metals as well as several post-transition metal ions...
December 5, 2018: Journal of Physical Chemistry. A
Karen Hakobyan, Thomas Gegenhuber, Christopher S P McErlean, Markus Muellner
The continuous amalgamation of photocatalysis into existing reversible deactivation radical polymerisation processes has initiated a rapidly propagating area of polymer research in recent years. We introduce bismuth oxide (Bi2O3) as a heterogeneous photocatalyst for polymerisations, operating at room temperature with visible light. We demonstrate formidable control over degenerative chain-transfer polymerisations, such as macromolecular design by interchange of xanthate (MADIX) and reversible addition-fragmentation chain transfer (RAFT) polymerisation...
December 3, 2018: Angewandte Chemie
Yanlan Wang, Didier Astruc, Alaa S Abd-El-Aziz
Since the development of metallopolymers, there has been tremendous interest in the applications of this type of materials. The interest in these materials stems from their potential use in industry as catalysts, biomedical agents in healthcare, energy storage and production as well as climate change mitigation. The past two decades have clearly shown exponential growth in the development of many new classes of metallopolymers that address these issues. Today, metallopolymers are considered to be at the forefront for discovering new and sustainable heterogeneous catalysts, therapeutics for drug-resistant diseases, energy storage and photovoltaics, molecular barometers and thermometers, as well as carbon dioxide sequesters...
December 3, 2018: Chemical Society Reviews
Fatemeh Rezaei, Davide Vione
Heterogeneous Fenton processes with solid catalysts have gained much attention for water and wastewater treatment in recent years. In the field of solid catalysts, zero valent iron (ZVI) is among the most applicable due to its stability, activity, pollutant degradation properties and environmental friendliness. The main limitation in the use of ZVI in heterogeneous Fenton systems is due to its deactivation in neutral and alkaline conditions, and Fenton-like processes have been developed to overcome this difficulty...
November 29, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
J Matthias Kahk, Johannes Lischner
Core-level X-ray Photoelectron Spectroscopy (XPS) is often used to study the surfaces of heterogeneous copper-based catalysts, but the interpretation of measured spectra, in particular the assignment of peaks to adsorbed species, can be extremely challenging. In this study we present a computational scheme which combines the use of slab models of the surface for geometry optimization with cluster models for core electron binding energy calculation. We demonstrate that by following this modelling strategy first principles calculations can be used to guide the analysis of experimental core level spectra of complex surfaces relevant to heterogeneous catalysis...
November 30, 2018: Physical Chemistry Chemical Physics: PCCP
Chenyue Sun, Grigorii Skorupskii, Jin-Hu Dou, Ashley M Wright, Mircea Dinca
The installation of metallo-ligands in metal-organic frameworks (MOFs) is an effective means to create site-isolated metal centers towards single-site heterogeneous catalysis. Although trispyrazolyborate (Tp) and tripyrazolylmethane (Tpm) form one of the most iconic classes of homogeneous catalysts, neither has been used as a metalloligand for the generation of MOFs thus far. Here, we show that upon in-situ metallation with CuI, a tricarboxylated Tpm ligand reacts with ZrOCl2 to generate a new MOF exhibiting neutral scorpionate-like chelating sites...
November 30, 2018: Journal of the American Chemical Society
Jacques Charles Védrine
This review paper aims at presenting actual knowledges, recent results and challenges for the future in heterogeneous oxidation catalysis in liquid and gaseous phases on solid metal oxide catalysts. Metal oxides, used as catalysts, and their main structures and properties are summarized, and, subsequently, also their catalytic properties in selective and total oxidation reactions, reactions which were studied intensively, experimentally and theoretically, by Professor Jerzy Haber during his scientific life...
November 29, 2018: ChemSusChem
Yun-Bing Zhou, Zhi-Kai Liu, Xin-Yang Fan, Ren-Hao Li, Guo-Liang Zhang, Li Chen, Ying-Ming Pan, Hai-Tao Tang, Jia-Hao Zeng, Zhuang-Ping Zhan
A porous organic polymer (POL-Xantphos) was synthesized and employed as a heterogeneous ligand for selective hydrosilylation of alkynes. It exhibits high selectivity and catalytic efficiency toward a broad range of alkynes. Owing to the confinement effect of the micropore structure, POL-Xantphos was far superior to the monomeric Xantphos ligands in controlling the selectivity. By performing hydrosilylation in a flow reactor system, separation and regeneration of the Ni/POL-Xantphos catalyst are easily achieved without any loss in selectivity or activity...
November 29, 2018: Organic Letters
Akira Oda, Takahiro Ohkubo, Takashi Yumura, Hisayoshi Kobayashi, Yasushige Kuroda
Oxygenase reactivity toward selective partial oxidation of CH4 to CH3 OH requires an atomic oxygen-radical bound to metal (M-O• : oxyl intermediate) that is capable of abstracting an H atom from the significantly strong C-H bond in CH4 . Because such a reaction is frequently observed in metal-doped zeolites, it has been recognized that the zeolite provides an environment that stabilizes the M-O• intermediate. However, no experimental data of M-O• have so far been discovered in the zeolite; thus, little is known about the correlation among the state of M-O• , its reactivity for CH4 , and the nature of the zeolite environment...
November 29, 2018: Inorganic Chemistry
Maryam Mashhadinezhad, Farhad Shirini, Manouchehr Mamaghani
Nanoporous Na+ -montmorillonite perchloric acid as a novel heterogeneous reusable solid acid catalyst was easily prepared by treatment of Na+ -montmorillonite as a cheap and commercially available support with perchloric acid. The catalyst was characterized using a variety of techniques including X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDX), pH analysis and determination of the Hammett acidity function...
April 1, 2019: Journal of Nanoscience and Nanotechnology
Fang Ren, Yue Yin, Yunyu Wang, Zhiqiang Liu, Meng Liang, Haiyan Ou, Jinping Ao, Tongbo Wei, Jianchang Yan, Guodong Yuan, Xiaoyan Yi, Junxi Wang, Jinmin Li
High density of defects and stress owing to the lattice and thermal mismatch between nitride materials and heterogeneous substrates have always been important problems and limit the development of nitride materials. In this paper, AlGaN light-emitting diodes (LEDs) were grown directly on a single-layer graphene-covered Si (111) substrate by metal organic chemical vapor deposition (MOCVD) without a metal catalyst. The nanorods was nucleated by AlGaN nucleation islands with a 35% Al composition, and included n-AlGaN, 6 period of AlGaN multiple quantum wells (MQWs), and p-AlGaN...
November 26, 2018: Materials
Sari Rautiainen, Davide Di Francesco, Sarmad Katea, Gunnar Westin, Duangamol Tungasita, Joseph Samec
Herein, we present a catalytic reductive fractionation of lignocellulose using a heterogeneous cobalt catalyst and formic acid or formate as a hydrogen donor. The catalytic reductive fractionation of untreated birch wood yield monophenolic compounds in up to 34 wt% yield of total lignin, and this corresponds to 76% of the theoretical maximum yield. By model compound studies, we found that the main role of the cobalt catalyst is to stabilize reactive intermediates formed during the organosolv pulping by transfer hydrogenation and hydrogenolysis reactions...
November 28, 2018: ChemSusChem
Masazumi Tamura, Keitaro Matsuda, Yoshinao Nakagawa, Keiichi Tomishige
CeO2 calcined at 1273 K showed higher activity per surface area than other metal oxides in the ring-opening polymerization of trimethylene carbonate under neat conditions without any additives, providing metal-free and additive-free poly(trimethylene carbonate) diols with no ether bonds with high selectivity. It was demonstrated that CeO2 was a robust and reusable heterogeneous catalyst.
November 28, 2018: Chemical Communications: Chem Comm
Katia González-Labrada, Romain Richard, Caroline Andriantsiferana, Héctor Valdés, Ulises J Jáuregui-Haza, Marie-Hélène Manero
Fluoroquinolones are extensively used in medicine due to their antimicrobial activity. Their presence in water inhibits microorganism activity in conventional wastewater treatment plants. This study aims to evaluate the technical feasibility of applying heterogeneous catalytic ozonation to eliminate ciprofloxacin (CIP) as a representative of fluoroquinolone antibiotics normally present in municipal wastewater discharges. Experiments were conducted in a semi-batch stirred slurry reactor, using 0.7 L of 100 mg L-1 CIP aqueous solution, at pH 3 and 30 °C...
November 27, 2018: Environmental Science and Pollution Research International
Gabriela Kratošová, Veronika Holišová, Zuzana Konvičková, Avinash P Ingle, Swapnil Gaikwad, Kateřina Škrlová, Aleš Prokop, Mahendra Rai, Daniela Plachá
Chemical, physical and mechanical methods of nanomaterial preparation are still regarded as mainstream methods, and the scientific community continues to search for new ways of nanomaterial preparation. The major objective of this review is to highlight the advantages of using green chemistry and bionanotechnology in the preparation of functional low-cost catalysts. Bionanotechnology employs biological principles and processes connected with bio-phase participation in both design and development of nano-structures and nano-materials, and the biosynthesis of metallic nanoparticles is becoming even more popular due to; (i) economic and ecologic effectiveness, (ii) simple one-step nanoparticle formation, stabilisation and biomass support and (iii) the possibility of bio-waste valorisation...
November 24, 2018: Biotechnology Advances
Xiaofeng Zhang, Qintie Lin, Haoyu Luo, Runlin Huang, Rongbo Xiao, Qianjun Liu
Rational modification of the surface structure and interface structure can effectively optimize the catalytic performance and stability of a heterogeneous catalyst. A CoO-CuO bimetallic catalyst with a special urchin-like structure was prepared by a hydrothermal urea precipitation method. This carbon nanosphere template method significantly improves the dispersibility of the material. The special urchin-like nanorod structure expands the specific surface area, resulting in excellent adsorption performance and high catalytic performance...
November 19, 2018: Science of the Total Environment
Yangxin Wang, Ningning Zhang, En Zhang, Yunhu Han, Zhenhui Qi, Marion Ansorge-Schumacher, Yan Ge, Changzhu Wu
In cooperative catalysis, the combination of chemo- and biocatalysts to perform one-pot synthetic route is a powerful tool for the improvement of chemical synthesis. Herein, UiO-66-NH2 was employed to stepwise immobilize Pd nanoparticles (NPs) and Candida antarctica lipase B (CalB) for the fabrication of biohybrid catalysts for cascade reaction. Distinct from traditional materials, UiO-66-NH2 has a robust but tunable structure which can be utilized with a ligand exchange approach to adjust its hydrophobicity, resulting in excellent catalyst dispersity in diverse reaction media...
November 26, 2018: Chemistry: a European Journal
Xin Jin, Tianqi Fang, Jinyao Wang, Mengyuan Liu, Siyuan Pan, Bala Subramaniam, Jian Shen, Chaohe Yang, Raghunath V Chaudhari
Conversion of biomass to chemicals provides essential products to human society from renewable resources. In this context, achieving atom-economical and energy-efficient conversion with high selectivity towards target products remains a key challenge. Recent developments in nanostructured catalysts address this challenge reporting remarkable performances in shape and morphology dependent catalysis by metals on nano scale in energy and environmental applications. In this review, most recent advances in synthesis of heterogeneous nanomaterials, surface characterization and catalytic performances for hydrogenation and oxidation for biorenewables with plausible mechanism have been discussed...
November 26, 2018: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
Belisa A Marinho, Raquel O Cristóvão, Rui A R Boaventura, Vítor J P Vilar
Water pollution by human activities is a global environmental problem that requires innovative solutions. Arsenic and chromium oxyanions are toxic compounds, introduced in the environment by both natural and anthropogenic activities. In this review, the speciation diagrams of arsenic and chromium oxyanions in aqueous solutions and the analytical methods used for their detection and quantification are presented. Current and potential treatment methods for As and Cr removal, such as adsorption, coagulation/flocculation, electrochemical, ion exchange, membrane separation, phyto- and bioremediation, biosorption, biofiltration, and oxidative/reductive processes, are presented with discussion of their advantages, drawbacks, and the main recent achievements...
November 24, 2018: Environmental Science and Pollution Research International
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