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1.
Mohammad A. Khalilzadeh Soo Young Kim Ho Won Jang Rafael Luque Rajender S. Varma Richard A. Venditti Mohammadreza Shokouhimehr 《Materials Today Chemistry》2022
The requirement of green and sustainable materials to prepare heterogeneous catalysts has intensified for practical reasons over the past few decades. Carbohydrates are possibly the most plentiful and renewable organic materials in nature with inimitable physiochemical properties, plausible low-cost and large-scale production, and sustainability features could be exploited in the generation of nanostructured heterogeneous catalysts. This review article outlines the organic transformations catalyzed by diverse carbohydrate-based nanostructured catalysts in greener and environmentally friendly processes. Selected examples are highlighted for a variety of organic reactions exploiting the proposed catalysts’ reactivity and reusability, and interactions with the intrinsic nature of the applied carbohydrate supports; advantages and speculated challenges of the introduced catalysts are deliberated as well. 相似文献
2.
《Comptes Rendus Chimie》2015,18(1):45-55
The aim of this work is to investigate the contribution of the binder (NiAl2O4) on the performances of the oxygen carrier NiO/NiAl2O4. To this purpose, oxidation/reduction cycles have been performed in a fixed bed reactor using CO as a fuel. The results reveal that the binder can react with the fuel to form CO2, and that its total reduction capacity increases with temperature. XRD characterizations performed on the binder (on the fresh and after several cycles) show a shift of the diffraction peaks of NiAl2O4 toward the ones of γ-alumina, which can be attributed to a progressive decomposition of NiAl2O4 to alumina and NiO. 相似文献
3.
《中国化学快报》2020,31(7):1899-1902
Herein, a series of carbazolyl cyanobenzene (CCB)-based organic photocatalysts with a broad range of photoredox capabilities were designed and synthesized, allowing precise control of the photocatalytic reactivity for the controllable reduction of aryl halides via a metal-free process. The screened-out CCB (5CzBN), a metal-free, low-cost, scalable and sustainable photocatalyst with both strong oxidative and reductive ability, exhibits superior performance for both dehalogenation and CC bond-forming arylation reactions. 相似文献
4.
Pt alloys with transition metals supported on carbon substrates are used as improved cathode electrocatalysts for fuel cells. Enhanced catalytic activity is attributed to the structure (Pt-Pt bond distance) and/or electronic effect (Pt d-electron vacancy). This work focuses on the development of Pt3Co/f-MWCNT catalysts (functionalized multiwalled carbon nanotubes [f-MWCNT]) using ethylene glycol as the dispersing and reducing agent. The aim is to in parallel achieve fine dispersion, quantitative deposition and alloy formation. As described herein, the pH value of the reaction suspension has a critical effect on the composition and morphology of the synthesized nanoparticles. High pH values favor the formation of Pt3Co alloy, nevertheless negatively influencing the dispersion. A discussion is made on the reduction/deposition mechanism and how to control the conditions to result in optimum properties. 相似文献
5.
6.
In an effort to reduce radiation exposure in the use of zircon minerals as opacity for the ceramic industry, it is required that the concentrations of UO2 and ThO2 contained in zircon must be less than 500 ppm. The purpose of this study was to reduce the concentration of UO2 and ThO2 in zircon minerals. The experimental investigation was initiated by synthesizing of calcium borate (CB), roasting of zircon concentrate with CB at various temperatures, and leaching with hydrochloric acid. The product quality of zircon minerals before and after roasting and leaching was characterized by Fourier Transform Infrared Spectrometer, X-Ray Diffractometer, and X-ray Fluorescence Spectrometer. The experimental results show that roasting zircon concentrate with CB at a zircon/CB ratio of 5/5 (weight/weight), a temperature of 1200 °C, a contact time of 3 h, and the leaching of the roasted results with 6 M HCl can reduce the total concentration of UO2 and ThO2 in zircon from 2008,1 ppm to 498.4 ppm. It can be concluded that the prototype zircon product from the experimental results has fulfilled the premium grade zircon with UO2 and ThO2 content of less than 500 ppm. 相似文献
7.
Dr. Soukaina Bennaamane Barbara Rialland Lhoussain Khrouz Dr. Marie Fustier-Boutignon Dr. Christophe Bucher Dr. Eric Clot Dr. Nicolas Mézailles 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(3):e202209102
Ammonia, NH3, is an essential molecule, being part of fertilizers. It is currently synthesized via the Haber–Bosch process, from the very stable dinitrogen molecule, N2 and dihydrogen, H2. This process requires high temperatures and pressures, thereby generating ca 1.6 % of the global CO2 emissions. Alternative strategies are needed to realize the functionalization of N2 to NH3 under mild conditions. Here, we show that boron-centered radicals provide a means of activating N2 at room temperature and atmospheric pressure whilst allowing a radical process to occur, leading to the production of borylamines. Subsequent hydrolysis released NH4+, the acidic form of NH3. EPR spectroscopy supported the intermediacy of radicals in the process, corroborated by DFT calculations, which rationalized the mechanism of the N2 functionalization by R2B radicals. 相似文献
8.
Heng Liu Luozhen Jiang Javid Khan Xinxin Wang Jiamin Xiao Handong Zhang Haijiao Xie Prof. Lina Li Prof. Shuangyin Wang Prof. Lei Han 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(3):e202214988
The regulation of electron distribution of single-atomic metal sites by atomic clusters is an effective strategy to boost their intrinsic activity of oxygen reduction reaction (ORR). Herein we report the construction of single-atomic Mn sites decorated with atomic clusters by an innovative combination of post-adsorption and secondary pyrolysis. The X-ray absorption spectroscopy confirms the formation of Mn sites via Mn-N4 coordination bonding to FeMn atomic clusters (FeMnac/Mn-N4C), which has been demonstrated theoretically to be conducive to the adsorption of molecular O2 and the break of O−O bond during the ORR process. Benefiting from the structural features above, the FeMnac/Mn-N4C catalyst exhibits excellent ORR activity with half-wave potential of 0.79 V in 0.5 M H2SO4 and 0.90 V in 0.1 M KOH as well as preeminent Zn-air battery performance. Such synthetic strategy may open up a route to construct highly active catalysts with tunable atomic structures for diverse applications. 相似文献
9.
Jiehao Du Banggui Cheng Huiqing Yuan Yuan Tao Ya Chen Mei Ming Zhiji Han Richard Eisenberg 《Angewandte Chemie (International ed. in English)》2023,62(9):e202211804
We report the unprecedented electrocatalytic activity of a series of molecular nickel thiolate complexes ( 1 – 5 ) in reducing CO2 to C1–3 hydrocarbons on carbon paper in pH-neutral aqueous solutions. Ni(mpo)2 ( 3 , mpo=2-mercaptopyridyl-N-oxide), Ni(pyS)3− ( 4 , pyS=2-mercaptopyridine), and Ni(mp)2− ( 5 , mp=2-mercaptophenolate) were found to generate C3 products from CO2 for the first time in molecular complex. Compound 5 exhibits Faradaic efficiencies (FEs) of 10.6 %, 7.2 %, 8.2 % for C1, C2, C3 hydrocarbons respectively at −1.0 V versus the reversible hydrogen electrode. Addition of CO to the system significantly promotes the FEC1–C3 to 41.1 %, suggesting that a key Ni−CO intermediate is associated with catalysis. A variety of spectroscopies have been performed to show that the structures of nickel complexes remain intact during CO2 reduction. 相似文献
10.
Dr. Lun An Patricia De La Torre Dr. Peter T. Smith Dr. Mina R. Narouz Prof. Christopher J. Chang 《Angewandte Chemie (International ed. in English)》2023,62(5):e202209396
We present a supramolecular approach to catalyzing photochemical CO2 reduction through second-sphere porosity and charge effects. An iron porphyrin box ( PB ) bearing 24 cationic groups, FePB-2(P) , was made via post-synthetic modification of an alkyne-functionalized supramolecular synthon. FePB-2(P) promotes the photochemical CO2 reduction reaction (CO2RR) with 97 % selectivity for CO product, achieving turnover numbers (TON) exceeding 7000 and initial turnover frequencies (TOFmax) reaching 1400 min−1. The cooperativity between porosity and charge results in a 41-fold increase in activity relative to the parent Fe tetraphenylporphyrin ( FeTPP ) catalyst, which is far greater than analogs that augment catalysis through porosity ( FePB-3(N ), 4-fold increase) or charge (Fe p-tetramethylanilinium porphyrin ( Fe-p-TMA ), 6-fold increase) alone. This work establishes that synergistic pendants in the secondary coordination sphere can be leveraged as a design element to augment catalysis at primary active sites within confined spaces. 相似文献