Влияние состояния TiO2 на окислительную делигнификацию древесины осины и соломы пшеницы

The influence of preparation methods on structural characteristics of TiO2 catalysts was studied by the XRD, SEM, BET, DTA-DSC, FTIR techniques. Catalytic activity of obtained titanium dioxide samples was compared in reaction of oxidative delignification of aspen wood and wheat straw by hydrogen peroxide in acetic acid- water medium. The use of titanium dioxide in rutile modification allows to produce a cellulose product with lower content of a residual lignin, as compared to TiO2 in anatase modification. The increase of surface area of the TiO2 catalyst reduces its activity in wood and wheat straw delignificationМетодами РФА, СЭМ, БЭТ, ДТА-ДСК, ИКС изучено влияние способов получения катализаторов TiO2 на их структурные характеристики. Сопоставлена каталитическая активность полученных образцов диоксида титана в реакции окислительной делигнификации древесины осины и соломы пшеницы пероксидом водорода в среде «уксусная кислота–вода». Использование диоксида титана в модификации рутил позволяет получить целлюлозный продукт с более низким содержанием остаточного лигнина, чем при использовании TiO2 в модификации анатаз. Увеличение удельной поверхности катализатора приводит к уменьшению степени делигнификации древесины осины и соломы пшениц

A Universal Approach to the Synthesis of Noble Metal Nanodendrites and Their Catalytic Properties

A universal approach is presented for high-yield synthesis of Au, Pt, and Pd nanoflowers using the surfactant sodium N-(4-n-dodecyloxybenzoyl)-L-isoleucinate (SDBIL). The pH-dependent self-assembly using SDBIL is critical for nanoflower growth. The Pt and Pd nanoflowers show superior catalytic activity for Suzuki–Miyaura and Heck coupling reactions over spherical counterparts

Nitro group reduction and Suzuki reaction catalysed by palladium supported on magnetic nanoparticles modified with carbon quantum dots generated from glycerol and urea

Glycerol and urea were used as green and cheap sources of carbon quantum dots (CQD) for modifying Fe3O4 nanoparticles (NPs). The obtained CQD@Fe3O4 NPs were used for the stabilization of palladium species and the prepared catalyst, Pd@CQD@Fe3O4, was characterized using various techniques. This magnetic supported palladium was applied as an efficient catalyst for the reduction of aromatic nitro compounds to primary amines at room temperature using very low palladium loading (0.008 mol%) and also for the Suzuki–Miyaura cross-coupling reaction of aryl halides as well as challenging heteroaryl bromides and aryl diazonium salts with arylboronic acids and with potassium phenyltrifluoroborate. This magnetically recyclable catalyst was recovered and reused for seven consecutive runs in the reduction of 4-nitrotoluene to p-toluidine and for ten consecutive runs in the reaction of 4-iodoanisole with phenylboronic acid with small decrease of activity. The catalyst reused in the Suzuki reaction was characterized using transmission electron microscopy, vibrating sample magnetometry and X-ray photoelectron spectroscopy. Using experiments such as hot filtration and poisoning tests, it has been shown that the true catalyst works under homogeneous conditions according to the release–return pathway of active palladium species.Iran National Science Foundation, Grant/Award Number: 95844587; the Generalitat Valenciana, Grant/Award Number: PROMETEOII/2014/017; the Spanish Ministerio de Economía, Industria y Competitividad, Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER, EU), Grant/Award Number: CTQ2016‐81797‐REDC and CTQ2016‐76782‐P; the Spanish Ministerio de Economía y Competitividad (MINECO), Grant/Award Number: CTQ2014‐51912‐REDC and CTQ2013‐43446‐P

Chain transfer kinetics of acid/base switchable n-aryl- n-pyridyl dithiocarbamate RAFT agents in methyl acrylate, n-vinylcarbazole and vinyl acetate polymerization

This is an accepted manuscript of an article published by American Chemistry Society in Macromolecules on 14/05/2012, available online: https://doi.org/10.1021/ma300616g ©American Chemical Society. The accepted version of the publication may differ from the final published version.The structures of the "Z" and "R" substituents of a RAFT agent (Z-C(S)S-R) determine a RAFT agent's ability to control radical polymerization. In this paper we report new acid/base switchable N-aryl-N-pyridyl dithiocarbamates (R = -CH 2CN, Z = -N(Py)(Ar)) which vary in substituent at the 4-position of the aryl ring and the use of these to control molecular weight and dispersity. In their protonated form, the new RAFT agents are more effective in controlling polymerization of the more activated monomer, methyl acrylate (MA), whereas in their neutral form they provide more effective control of the polymerization of less activated monomers, N-vinyl carbazole (NVC) and vinyl acetate (VAc). For each polymerization, the apparent chain transfer coefficient (C trapp) shows a good correlation with Hammett parameters. Dithiocarbamates with more electron-withdrawing aryl ring substituents have the higher C trapp. This demonstrates the influence of polar effects on C trapp and supports the hypothesis that the activity of these RAFT agents is determined by the availability of the lone pair of the dithiocarbamate nitrogen.The authors gratefully acknowledge the Capability Development Fund of CSIRO Materials Science and Engineering for financial support.Published versio

A Landscape of Lignocellulosic Biopolymer Transformations into Valuable Molecules by Heterogeneous Catalysis in C’Durable Team at IRCELYON

This review article highlights part of the research activity of the C’Durable team at IRCELYON in the field of sustainable chemistry. This review presents a landscape of the work performed on the valorization of lignocellulosic biopolymers. These studies intend to transform cellulose, hemicellulose and lignin into valuable molecules. The methodology usually consists in evaluating the behavior of the biopolymers in the absence of catalyst under various conditions (solvent, temperature), and then to assess the influence of a catalyst, most often a heterogeneous catalyst, on the reactivity. The most significant results obtained on the upgrading of cellulose and lignin, which have been mainly investigated in the team, will be presented with an opening on studies involving raw lignocellulose