Diffusion-controlled synthesis of Cu-based for the Rochow reaction

Abstract

The properties of materials are strongly dependent on their structures. The diffusion effect is a main kinetic factor that can be used to regulate the growth and structure of materials. In this work, we developed a systematic and feasible strategy to synthesize Cu 2 O solid spheres and hexahedrons by controlling the diffusion coefficients. These Cu 2 O products can be successively transformed into corresponding Cu hollow spheres and hexahedrons as well as CuO porous spheres and hexahedrons by controlling hydrogen diffusion in hydrazine hydrate solution and controlling oxygen diffusion in air, respectively. The formation of these transformations was also discussed in detail. Tested for Rochow reaction, the as-prepared Cu 2 O solid and CuO porous spheres exhibit higher dimethyldichlorosilane selectivity and Si conversion than Cu hollow spheres, which is attributed to the active sites for CH 3 Cl adsorption formed in Cu x Si phase after the removal of oxygen atoms in Cu 2 O and CuO in the formation of dimethylchlorosilane. The present work not only develops a feasible method for preparing well shape-defined Cu 2 O solid spheres and hexahedrons but also clarifies the respective roles of Cu, Cu 2 O and CuO in dimethyldichlorosilane synthesis via Rochow reaction.

Recent Advances in Rochow‐Müller Process Research: Driving to Molecular Catalysis and to A More Sustainable Silicone Industry

“…; (3) focusing on different perspectives. For instance, some researchers paid their primary attention to the thermodynamics, while some others to kinetics, and the rest emphasized more on the electronic structures or effects of catalyst‐promoter systems themselves . In general, the synergetic interactions of promoters with the main active components of the catalysts in different systems are of interest but not very clear.…”

“…The discovery of the indium promoter helped to explain the effects of Zn, Sn, and P. Zhang et al reported that in a Rochow‐Müller system, the catalytic function can be generated via two types of interfaces (Figure a) . “Interface” 1 is the “P−N junctions” generated between P‐type CuO and N‐type In 2 O 3 .…”

Cu2O/2D COFs Core/Shell Nanocubes with Antiphotocorrosion Ability for Efficient Photocatalytic Hydrogen Evolution

“…Powder X-ray diffraction (XRD) pattern demonstrates that the Cu 2 O nanocube has the characteristic peaks located at ∼30°, ∼36°, ∼43°, ∼62°, and ∼74°, ascribed to the (101), (111), (200), (220), and (311) facets, respectively (Figure S3). , The surface exposed Cu atom of Cu 2 O nanocube can provide anchor sites for PyTTA, which is important for conducting the following Schiff base reaction between PyTTA and TPA. , SEM image of as-made Cu 2 O/PyTTA-TPA COFs hybrid shows the uniform nanocube morphology (Figure S4). TEM image of Cu 2 O/PyTTA-TPA COFs nanocubes reveal that they have the typical core/shell structure (Figure b).…”

Effect of Copper Catalyst Content and Zinc Promoter on Carbon Formation in the Direct Synthesis of Methylchlorosilanes

“…The broad product distribution and the small impurities in the metallurgical grade silicon (i.e., Fe, Al, Ca, etc.) add to the complexity. ,,, Several Cu-based compounds such as CuO, Cu 2 O, CuCl, and also combinations thereof have been used as the catalyst precursors in the MCS synthesis. − CuCl is regarded as efficient in this respect, since it not only reduces the induction period but also increases the selectivity toward M2 . Several other metals are reported to enhance the catalytic activity, selectivity, and stability of copper in the direct process. − For example, there is a general agreement in the literature that zinc (Zn) increases the selectivity toward M2, , and that its copromotion with tin (Sn) results in a synergistic relationship that increases both reaction rate and M2 selectivity. , …”

“…The reaction between chloromethane (CH 3 Cl, also called methyl chloride) and silicon (Si) to synthesize methylchlorosilanes (MCS), also known as the Müller-Rochow Synthesis or the Direct Process, is currently the most convenient and economical way to produce MCS industrially. Almost 90% of the starting materials for current silicone manufacturing are obtained with MCS monomers. − On an industrial scale, ground metallurgical grade silicon is mixed with a copper-based catalyst − and minor amounts of various other promoter elements − in a fluidized bed reactor under gaseous CH 3 Cl, at temperature and pressure ranging between 280–350 °C and 1–10 bar. , This quite unique gas (CH 3 Cl)–solid (Si)–solid (Cu-based catalyst) heterogeneous reaction exhibits a complicated dependency on reaction temperature, (partial) pressure(s), reactor type, residence time distribution, and phase/component interactions. , The latter incorporates nature, purity, size distribution, morphology, and proportion of silicon to copper catalyst precursor and promoters . Moreover, a range of methylchlorosilanes, (CH 3 ) x SiCl 4– x , is formed although the dominant and main product of interest is dimethyldichlorosilane, (CH 3 ) 2 SiCl 2 , also referred to as “M2” .…”