Palladium-Nafion SAC-13 catalysed depolymerisation of lignin to phenols in formic acid and water

Guaiacol, pyrocatechol and resorcinol, were isolated and quantified as the major products from catalytic pyrolysis of lignin of various origin. The novel procedure utilises formic acid as the hydrogen source in combination with a palladium catalyst and Nafion^® SAC-13 as a solid acid catalyst with water as reaction medium. The reaction is conducted at moderate pyrolysis temperature and short reaction time. Several palladium based catalysts and different types of lignin were investigated. The lignins and the model compounds demonstrated various chemical behaviour, under identical reaction conditions; various phenols were formed from the lignins, while the model compounds were hydrodeoxygenated, demethylated and demethoxylated.     

Hydrodehalogenation of 4-chlorophenol and 4-bromophenol over Pd–Fe/Al2O3: influence of catalyst reduction conditions

The reduction of monometallic Pd/Al₂O₃ and bimetallic PdFe/Al₂O₃ catalysts produced by co-impregnation or sequential impregnation of the support with metal salts was possible not only under high temperature hydrogen treatment but also at 30 °C under the action of aqueous phenol solution and hydrogen. According to the XPS data, both reduction routes provided sufficient degrees of Pd reduction required for fast hydrodehalogenation of 4-chlorophenol and 4-bromophenol to phenol in aqueous solutions. The degree of Pd reduction was higher in the co-impregnated bimetallic PdFe catalyst, which was more efficient in transformation of 4-bromophenol; the bimetallic catalysts were more stable than the monometallic Pd one in the conversion of 4-chlorophenol.     

The Catalytic Mechanism of Human Transketolase

We have computationally determined the catalytic mechanism of human transketolase (hTK) using a cluster model approach and density functional theory calculations. We were able to determine all the relevant structures, bringing solid evidences to the proposed experimental mechanism, and to add important detail to the structure of the transition states and the energy profile associated with catalysis. Furthermore, we have established the existence of a crucial intermediate of the catalytic cycle, in agreement with experiments. The calculated data brought new insights to hTK′s catalytic mechanism, providing free-energy values for the chemical reaction, as well as adding atomistic detail to the experimental mechanism.     

New less toxic zeolite‐encapsulated Cu(II) complex nanomaterial for dual applications in biomedical field and wastewater remediation

A new dual‐functional Cu(II) complex and its nanohybrid form encapsulated into NaY zeolite cavities were synthesized. The synthesized compounds were characterized using elemental analyses, X‐ray fluorescence, infrared, ¹H NMR, electronic, electron spin resonance and mass spectra, powder X‐ray diffraction, surface area and transmission electron microscopy in addition to conductivity and magnetic susceptibility measurements. The encapsulated Cu(II) complex was catalytically tested for degradation of industrial wastewater. The decolorization and mineralization results indicate that the Cu(II) complex encapsulated into zeolite host is an effective heterogeneous catalyst for real industrial wastewater remediation. In addition, both free and encapsulated Cu(II) complexes were tested as anti‐microbial and anti‐tumour agents. The results show that the Cu(II) complex encapsulated into zeolite has a high activity (IC₅₀ = 14.4 μg ml^?1). The results of in vivo toxicity experiments indicate that the Cu(II) complex encapsulated into zeolite is a less toxic biocompatible material (LD₅₀ = 1245 mg kg^?1). The catalytic properties, cytotoxicity and toxicity of the new nanohybrid Cu(II) complex encapsulated into zeolite make it a promising eco‐friendly and biocompatible material for water remediation and biomedical applications.     

Research on mechanism of gas liquid separation in SO2 removal from flue gas by liquid absorption with catalysed reaction

The desulphurised experiment of an organic physical solvent of dimethyl sulphoxide (DMSO) mixed with a relatively small amount of Mn(II) catalyst, based on the novel desulphurisation technology using the organic solvent as absorbent, is studied. Results indicate that Mn(II) plays a significant catalytic role. Compared with pure physical solvent of DMSO, the purification efficiency of SO₂ with a small amount of catalyst has been much improved, and its absorption and reaction mechanism by liquid absorption with catalysed reaction are discussed.     

Asymmetric Catalytic Assembly of Triple-Columned and Multilayered Chiral Folding Polymers Showing Aggregation-Induced Emission (AIE)

Unprecedented chiral multilayer folding 3D polymers have been assembled and regulated by uniform and differentiated aromatic chromophore units between naphthyl piers. Screening catalysts, catalytic systems and monomers were proven to be crucial for asymmetric catalytic Suzuki–Miyaura polycouplings for this assembly. X-ray crystallography of the corresponding dimers and trimers revealed the absolute configuration and the intermolecular packing pattern. Up to 61 960 M_w/41 900 M_n and m/z 4317 for polymers and oligomers, as confirmed by gel permeation chromatography (GPC) and MALDI-TOF MS, indicated that these frameworks were composed of multiple stacked layers. The resulting multiple π-assemblies exhibited remarkable optical properties in aggregated states (photoluminescence in solids and aggregation-induced emission in solutions), as well as reversible redox properties in electrochemical performance.     

Recombination of hydrogen atoms on fine-grain graphite

The probability of recombination of hydrogen atoms on surfaces of fine-grain graphite EK98 was investigated as a function of surface roughness. The source of hydrogen atoms used in this experiment was weakly ionised plasma created with an inductively coupled radiofrequency generator at pressures from 30 Pa to 175 Pa in hydrogen. Hydrogen atom density was measured by means of fibre optic catalytic probes. The recombination coefficient of the graphite samples was determined by observing their impact on the spatial distribution of the atom density in a closed side-arm of the reactor. Smith's diffusion model was used to calculate the values of the recombination coefficient. The measured recombination coefficient was found to increase much faster than the measured effective surface. This discrepancy is explained by the fact that on a surface which is not perfectly flat, there is a finite probability for multiple collisions. Impinging atoms collide more than once with the surface before they are reflected into the surface, which results in a larger probability of recombination.     

Silicotungstic acid modified Ce‐Fe‐Ox catalyst for selective catalytic reduction of NOx with NH3: Effect of the amount of HSiW

The HSiW(x)/Ce‐Fe catalysts were used to research the effect of silicotungstic acid contents on the catalytic activity in the selective catalytic reduction of NO_x with NH₃. Doping different contents of silicotungstic acid affected surface species and redox property as well as the catalytic activity. With the increasing amount of HSiW (x = 5%, 10% and 20%), the redox reaction between Fe³⁺/Fe²⁺ and Ce⁴⁺/Ce³⁺ enhanced, which could improve the ratio of Ce³⁺ and Fe³⁺. And then, more Ce³⁺ increased the ratio of chemisorbed oxygen (O_α). Besides, the type and strength of acid sites over HSiW(_x)/Ce‐Fe was affected by the HSiW contents. These factors facilitated the catalytic performance. Thus, the NO_x conversion of HSiW(x)/Ce‐Fe(x = 20%) was higher than 90%, which maintained in a wide temperature range between 200 and 400 °C.     

Promotional effect of acidic oxide on catalytic activity and N2 selectivity over CeO2 for selective catalytic reduction of NOx by NH3

The CeO₂, CeO₂‐ZrO₂ and CeO₂‐WO₃ catalysts were prepared by hydrothermal method and used to the selective catalytic reduction of NO_x by NH₃. The addition of ZrO₂ or WO₃ into CeO₂ was favorable for pore structure, and then improved the number of active sites. Besides, the introduction of ZrO₂ into CeO₂ could improve the Lewis acid sites while WO₃ could contribute to the generation of Brønsted and Lewis acid sites, which could improve the catalytic performance and N₂ selectivity. The CeO₂‐WO₃ catalyst exhibited optimal catalytic activity with above 90% NO_x conversion performance at 220–425 °C and approximately 100% N₂ selectivity at 150–425 °C.     

非酶催化法测定食品中微量铜的研究进展

随着人们生活水平的提高和健康意识的增强,食品安全越来越受到关注.非酶催化分析法具有灵敏度高,且操作简单,检测快速的特点,本文综述了近年来非酶催化法在食品铜含量测定中的应用情况,分析了其局限性,并对其应用前景进行了展望.