Application of mesoporous carbon nitride as a support for an Au catalyst for acetylene hydrochlorination

One-step preparation of well-dispersed spindle-like Fe2O3 nanoparticles on g-C3N4 as highly efficient photocatalysts

Photocatalysis has attracted wide attention due to its outstanding advantages in dealing with sewage. And compounds of metal oxides and g-C₃N₄ that possess Z-type heterojunctions have become the star photocatalysts in degrading pollutants. In this paper, a novel one-step method for the preparation of highly efficient photocatalyst of Fe₂O₃/g-C₃N₄, using Fe (NO₃)₃ and urea as raw materials, is described. Under the optimized condition, the one-step synthesized photocatalyst of FeGCN-0.10 showed higher photocatalytic performance compared with the multi-step prepared photocatalyst, and the rate of removing basic fuchsin was 92% (210 min), which was 19.5% higher than that of the latter. Furthermore, different methods were also applied for characterizing Fe₂O₃/g-C₃N_4. Structural characterization results confirmed the composites of Fe₂O₃/g-C₃N₄. Morphological characterization results showed that spindle-like Fe₂O₃ particles were distributed more evenly on the layered g-C₃N₄ compared with the impregnation method. Optical characterization results demonstrated the high intensity of the separated photo-generated electron-hole pairs and of Fe₂O₃/g-C₃N₄, which uncovered the removing mechanism of basic fuchsin.

A study on the rules of ligands in highly efficient Ru–amide/AC catalysts for acetylene hydrochlorination

The electron donor ability and steric hindrance of substituents on amide ligands jointly affect the modification effect of ligands on ruthenium based catalysts for acetylene hydrochlorination.

Carbon-Based Materials for the Development of Highly Dispersed Metal Catalysts: Towards Highly Performant Catalysts for Fine Chemical Synthesis

Single-atom catalysts (SACs), consisting of metals atomically dispersed on a support, are considered as advanced materials bridging homogeneous and heterogeneous catalysis, representing the catalysis at the limit. The enhanced performance of these catalysts is due to the combination of distinct factors such as well-defined active sites, comprising metal single atoms in different coordination environments also varying its valence state and strongly interacting with the support, in this case porous carbons, maximizing then the metal efficiency in comparison with other metal surfaces consisting of metal clusters and/or metal nanoparticles. The purpose of this review is to summarize the most recent advances in terms of both synthetic strategies of producing porous carbon-derived SACs but also its application to green synthesis of highly valuable compounds, an area in which the homogeneous catalysts are classically used. Porous carbon-derived SACs emerge as a type of new and eco-friendly catalysts with great potential. Different types of carbon forms, such as multi-wall carbon nanotubes (MWCNTs), graphene and graphitic carbon nitride or even others porous carbons derived from Metal–Organic-Frameworks (MOFs) are recognized. Although it represents an area of expansion, experimentally and theoretically, much more future efforts are needed to explore them in green fine chemical synthesis.

Progress and Challenges of Mercury-Free Catalysis for Acetylene Hydrochlorination

Activated carbon-supported HgCl2 catalyst has been used widely in acetylene hydrochlorination in the chlor-alkali chemical industry. However, HgCl2 is an extremely toxic pollutant. It is not only harmful to human health but also pollutes the environment. Therefore, the design and synthesis of mercury-free and environmentally benign catalysts with high activity has become an urgent need for vinyl chloride monomer (VCM) production. This review summarizes research progress on the design and development of mercury-free catalysts for acetylene hydrochlorination. Three types of catalysts for acetylene hydrochlorination in the chlor-alkali chemical industry are discussed. These catalysts are a noble metal catalyst, non-noble metal catalyst, and non-metallic catalyst. This review serves as a guide in terms of the catalyst design, properties, and catalytic mechanism of mercury-free catalyst for the acetylene hydrochlorination of VCM. The key problems and issues are discussed, and future trends are envisioned.

Hydrogen Production from Formic Acid over Au Catalysts Supported on Carbon: Comparison with Au Catalysts Supported on SiO2 and Al2O3

Characteristics and catalytic activity in hydrogen production from formic acid of Au catalysts supported on porous N-free (Au/C) and N-doped carbon (Au/N-C) have been compared with those of Au/SiO2 and Au/Al2O3 catalysts. Among the catalysts examined, the Au/N-C catalyst showed the highest Au mass-based catalytic activity. The following trend was found at 448 K: Au/N-C > Au/SiO2 > Au/Al2O3, Au/C. The trend for the selectivity in hydrogen production was different: Au/C (99.5%) > Au/Al2O3 (98.0%) > Au/N-C (96.3%) > Au/SiO2 (83.0%). According to XPS data the Au was present in metallic state in all catalysts after the reaction. TEM analysis revealed that the use of the N-C support allowed obtaining highly dispersed Au nanoparticles with a mean size of about 2 nm, which was close to those for the Au catalysts on the oxide supports. However, it was by a factor of 5 smaller than that for the Au/C catalyst. The difference in dispersion could explain the difference in the catalytic activity for the carbon-based catalysts. Additionally, the high activity of the Au/N-C catalyst could be related to the presence of pyridinic type nitrogen on the N-doped carbon surface, which activates the formic acid molecule forming pyridinium formate species further interacting with Au. This was confirmed by density functional theory (DFT) calculations. The results of this study may assist the development of novel Au catalysts for different catalytic reactions.

An efficient Au catalyst supported on hollow carbon spheres for acetylene hydrochlorination

Mesoporous hollow carbon spheres (HCS) were prepared and applied as the support of Au catalyst for acetylene hydrochlorination. Au/HCS exhibited excellent stability for acetylene hydrochlorination.

Wheat flour-derived N-doped mesoporous carbon extrudate as superior metal-free catalysts for acetylene hydrochlorination

The As metal free catalysts, the wheat flour/gluten derived granular N-doped mesoporous carbons featured superior catalytic performance for acetylene hydrochlorination.

Recent advances in functional mesoporous graphitic carbon nitride (mpg-C3N4) polymers

Mesoporous micro-/nanostructures acting as supports for catalysts or used directly in catalysis reactions generally show fascinating performances that could lead to great potential for application. In the past few decades, extensive efforts have been devoted to the exploration and enrichment of graphitic carbon nitride (g-C₃N₄) based research. Especially, mesoporous g-C₃N₄ (mpg-C₃N₄) with controllable porosity and electronic/atomic structure can bring to bear unique physicochemical properties and has been widely applied in the fields of photocatalysis, adsorbents, sensors and chemical templates. However, a comprehensive summary on mpg-C₃N₄ micro/nanostructures is less reported and there is an urgent need to further promote the development of function-oriented mpg-C₃N₄-based materials. Herein, we will overview the significant advances in functional mpg-C₃N₄ polymers, including general synthesis strategies and growth mechanisms, modifications of electronic/atomic structures and interfacial properties (such as exfoliation, doping and hybridizing), as well as their current applications. Finally, several emerging issues and perspectives are also proposed.

Capping agent-free highly dispersed noble metal nanoparticles supported in ordered mesoporous carbon with short channels and their catalytic applications

Capping agent free synthesis of noble metal nanoparticles supported on ordered mesoporous carbon with short channels.

Novel AuCl3–thiourea catalyst with a low Au content and an excellent catalytic performance for acetylene hydrochlorination

In this work, we synthesized a novel non-mercuric catalyst with HAuCl₄·4H₂O and thiourea as precursors, and active carbon (AC) as a support.