Elucidating the role of confinement and shielding effect over zeolite enveloped Ru catalysts for propane low temperature degradation.

Volatile organic compounds (VOCs) are the main precursor for ozone formation and hazardous to human health. Light alkane as one of the typical VOCs is difficult to degrade to CO2 and H2O by catalytic degradation method due to its strong C-H bond. Herein, a series of ultrafine Ru nanoclusters (<0.95 nm) enveloped in silicalite-1 (S-1) zeolite catalysts were designed and prepared by a simple one-pot method and applied for catalytic degradation of propane. The results demonstrate that the enveloped Ru1@S-1 catalyst has excellent propane degradation performance. Its T95 is as low as 294 °C with moisture, and the turnover frequency (TOF) value is up to 5.07 × 10-3 s-1, evidently higher than that of the comparison supported catalyst (Ru1/S-1). Importantly, Ru1@S-1 exhibits superior thermal stability, water resistance and recyclability, which should be attributed to the confinement and shielding effect of the S-1 shell. The in-situ DRIFTS result reveals that the propane degradation over Ru1@S-1 follows the Mars-van-Krevelen (MvK) mechanism, where the hydroxy from the framework of zeolite can provide the active oxygen species. Our work provides a new candidate and guideline for an efficient and stable catalyst for the low-temperature degradation of the light alkane VOCs.

Determination of ADH in textiles using the HPLC-MS/MS method and the study of its adsorption behaviour towards formaldehyde.

In the textile industry, formaldehyde-based resins are used as finishers to make the fabrics crease-resistant, which are the main source of formaldehyde in textiles. In our practical study, there are cases that prove that textile products containing adipic dihydrazide (ADH) will continuously adsorb formaldehyde from the surrounding environment during storage. In this study, a high performance liquid chromatography-tandem mass spectrometry method was established for the precise determination of ADH in textiles. The method was optimized in terms of instrument conditions, extraction temperature, extraction time, and extraction mode. Under optimum test conditions, ADH was determined precisely with the linearity range of 0.05-2 mg L-1 and correlation coefficient (R 2) of 0.9993. Recovery rate and repeatability were tested; the data showed that the recovery rate of ADH in textiles was in the range of 85-100%, and the RSD (relative standard deviation) was less than 10%. The ADH-positive textile samples were placed in designed environments for some time to adsorb formaldehyde. The adsorbed amounts of formaldehyde in the textile samples first increase and then decrease with time. The maximum amount of formaldehyde a sample can adsorb increases with an increase in its ADH content and will stop increasing once its ADH content exceeds 1700 mg kg-1. The placement environment has a little effect on the maximum adsorption capacity of the samples towards formaldehyde, but can significantly affect the adsorption rate and equilibrium adsorption capacity.

Assessing the influence of side-chain and main-chain aromatic benzyltrimethyl ammonium on anion exchange membranes.

3,3'-Di(4″-methyl-phenyl)-4,4'-difluorodiphenyl sulfone (DMPDFPS), a new monomer with two pendent benzyl groups, was easily prepared by Suzuki coupling reaction in high yield. A series of side-chain type ionomers (PAES-Qs) containing pendant side-chain benzyltrimethylammonium groups, which linked to the backbone by alkaline resisting conjugated C-C bonds, were synthesized via polycondensation, bromination, followed by quaternization and alkalization. To assess the influence of side-chain and main-chain aromatic benzyltrimethylammonium on anion exchange membranes (AEMs), the main-chain type ionomers (MPAES-Qs) with the same backbone were synthesized following the similar procedure. GPC and (1)H NMR results indicate that the bromination shows no reaction selectivity of polymer configurations and ionizations of the side-chain type polymers display higher conversions than that of the main-chain type ones do. These two kinds of AEMs were evaluated in terms of ion exchange capacity (IEC), water uptake, swelling ratio, λ, volumetric ion exchange capacity (IECVwet), hydroxide conductivity, mechanical and thermal properties, and chemical stability, respectively. The side-chain type structure endows AEMs with lower water uptake, swelling ratio and λ, higher IECVwet, much higher hydroxide conductivity, more robust dimensional stability, mechanical and thermal properties, and higher stability in hot alkaline solution. The side-chain type cationic groups containing molecular configurations have the distinction of being practical AEMs and membrane electrode assemblies of AEMFCs.