Influence of Microwave Irradiation on the Structural Properties of Carbon-Supported Hollow Copper Nanoparticles and Their Effect on the Synthesis of Dimethyl Carbonate

New Strategies on Green Synthesis of Dimethyl Carbonate from Carbon Dioxide and Methanol over Oxide Composites

Dimethyl carbonate is a generally used chemical substance which is environmentally sustainable in nature and used in a range of industrial applications as intermediate. Although various methods, including methanol phosgenation, transesterification and oxidative carbonylation of methanol, have been developed for large-scale industrial production of DMC, they are expensive, unsafe and use noxious raw materials. Green production of DMC from CO2 and methanol is the most appropriate and eco-friendly method. Numerous catalysts were studied and tested in this regard. The issues of low yield and difficulty in tests have not been resolved fundamentally, which is caused by the inherent problems of the synthetic pathway and limitations imposed by thermodynamics. Electron-assisted activation of CO2 and membrane reactors which can separate products in real-time giving a maximum yield of DMC are also being used in the quest to find more effective production method. In this review paper, we deeply addressed green production methods of DMC using Zr/Ce/Cu-based nanocomposites as catalysts. Moreover, the relationship between the structure and activity of catalysts, catalytic mechanisms, molecular activation and active sites identification of catalysts are also discussed.

Carbon nanotube-supported Cu-based catalysts for oxidative carbonylation of methanol to methyl carbonate: effect of nanotube pore size

The inner diameter of CNTs significantly affected the location, dispersion, autoreduction and stability of Cu species and thus the catalytic activity and stability for oxidative carbonylation of methanol to dimethyl carbonate.

Multiscale Simulation of Morphology Evolution of Supported Pt Nanoparticles via Interfacial Control

The structural and electronic properties of the interface are critical for the morphology of supported metal nanoparticles and thus the performance in catalysis, photonics, biomedical research, and other areas. To reveal the intrinsic mechanism of the formation of various morphologies, a multiscale simulation strategy is adopted to bridge the macroscopic structures by experimental observations and microscopic properties by theoretical calculations. This strategy incorporates the density functional theory (DFT) for the interaction energy calculation, the molecular dynamics (MD) simulation for the structure evolution, and theoretical model for the correlation with contact angles. The interaction energies between Pt atoms (four-atom clusters) and substrates are applied for the force field parametrization in the following MD simulation. Simulation results show the binding energies and structural properties such as radial distribution function and coordination number for supported metal nanoparticles with various sizes in detail. Notably, the contact angles of supported nanoparticles are well correlated by the strength of metal-support interactions. This work yields guidelines on the structure modulation of supported metal nanoparticles via interfacial control.

Hollow porous Cu particles from silica-encapsulated Cu2O nanoparticle aggregates effectively catalyze 4-nitrophenol reduction

A hollow metal micro/nanomaterial with a porous wall is one of the most attractive structures for catalysts. The synthesis of hollow porous Cu particles remains a challenge due to their air-sensitive characteristics. In this study, we report a facile and scalable method for the preparation of high-quality hollow porous Cu particles in the range of 500 nm-1.5 μm with a well-defined structure from Cu₂O nanoparticle aggregates (NPAs). The synthetic procedure involves the silica-encapsulation and depth-controlled reduction of Cu₂O NPAs followed by heat-treatment in air and selective removal of the encapsulating layer. The catalytic performance of the hollow porous Cu particles was evaluated through the catalytic reduction of 4-nitrophenol with NaBH₄ as a model reaction. The hollow porous Cu particles exhibited a high activity factor, K = 186 s^-1 g^-1, which is the highest K value obtained among the unsupported Cu catalysts to date. And the K value is better than that of some noble metal catalysts, such as Au, Ag, and Pd. In addition, the catalyst could be easily separated from the reaction system and still possessed high activity as well as stability in recycled reactions.