Fabrication and characterization of mesoporous yolk-shell nanocomposites as an effective reusable heterogeneous base catalyst for the synthesis of ortho-aminocarbonitrile tetrahydronaphthalenes

Mesoporous yolk-shell nanocomposites (MYSNs) were loaded with a mobile CaMg core inside the silica shell. CaMg@MYS nanocomposites have been effectively prepared inside the inner cavity of a novel structure that consists of hollow mesoporous silica spheres. Tetraethyl orthosilicate (TEOS) and an amount of cetyltrimethylammonium bromide (CTAB) are coated on the carbon spheres used as a hard template in the multi-step synthetic procedure. In this method, the target products were obtained in high to excellent yields between 87-96% and quick response times between 10-20 minutes under mild conditions. The CaMg@MYS catalyst shows promise as an efficient and reusable catalyst in multicomponent processes. The CaMg@MYS multi-yolk spheres compared to metal oxide nanostructures indicated both high catalytic performance and a significant factor as a novelty. To identify each product, FT-IR, ¹H NMR, and melting point techniques were applied. Also, in order to characterize the prepared catalysts, FT-IR, XRD, FE-SEM, EDS, elemental mapping, and HR-TEM techniques were applied.

One-step hydrothermal preparation of Ta-doped ZnO nanorods for improving decolorization efficiency under visible light

In this work, Ta-doped ZnO (Ta-ZnO) nanomaterials were synthesized by the hydrothermal method at different temperatures (110, 150, and 170 °C) for the photodegradation of methylene blue (MB) under visible light. Ta doping significantly affects the crystal defects, optical properties, and MB photocatalytic efficiency of ZnO materials. The optical absorption edge of Ta-ZnO 150 was redshifted compared to undoped ZnO, correlating to bandgap narrowing (E _gTa-ZnO = 2.92 eV; E _gZnO = 3.07 eV), implying that Ta doped ZnO is capable of absorbing visible light. Besides, Ta-doping was the reason for enhanced blue light emission in the photoluminescence spectrum, which is related to the oxygen defect V ⁰ _O. It is also observed in the XPS spectra, where the percentage of oxygen in the oxygen-deficient regions (O_531.5 eV) of Ta-ZnO150 is higher than that of ZnO150. It is an important factor in enhancing ZnO's photocatalytic efficiency. The MB degradation efficiency of Ta-doped ZnO reached the highest for Ta-ZnO 150 and was 2.5 times higher than ZnO under a halogen lamp (HL). Notably, the influence of hydrothermal temperature on the structural, morphological, and photoelectrochemical properties was discussed in detail. As a result, the optimal hydrothermal temperature for synthesizing the nanorod is 150 °C. Furthermore, photocatalytic experiments were also performed under simulated sunlight and natural sunlight. The nature of the photo-oxidative degradation of MB was also investigated.

Lignin-based adsorbent-catalyst with high capacity and stability for polychlorinated aromatics removal

The utilization of lignin as carbonaceous material for pollution adsorption provides an alternative way for lignocellulose valorization. Here in, lignin-based adsorbents (i.e., LC-A, LC-B, and LC-C) were prepared and used for the removal of o-DCB (a toxic gaseous pollutant). LC-B exhibited the best adsorption capacity (718.2 mg/g) when comparing with LC-A (93.1 mg/g), LC-C (10.2 mg/g), and activated carbon (72.7 mg/g). LC-B also demonstrated excellent recycling stability with the adsorption capacity of 710.8 mg/g after five runs. More importantly, LC-B supported Ru adsorbent catalyst could effectively remove o-DCB with removal rate >80% under a wide range of temperature (50-300°C). The excellent performance of lignin-based adsorbents could be attributed to its abundant pore structure, high specific surface area (1618.55 m²/g), enhanced graphitization degree as well as the abundant hydroxyl functional groups. The present work provided a cost-effective strategy for pollution control by lignin-based material.

Effect of Ce doping on the structure–activity relationship of MoVOx composite metal oxides

Ce-doped MoVOx with disperse rod-shaped exhibits excellent catalytic performance in selective oxidation of benzyl alcohol.