Intercalating lithium into the lattice of silver nanoparticles boosts catalytic hydrogenation of carbon-oxygen bonds

Monitoring Photoinduced Interparticle Chemical Communication In Situ

Monitoring interparticle chemical communication plays a critical role in the nanomaterial synthesis as this communication controls the final structure and stability of global nanoparticles (NPs). Yet most ensemble analytical techniques, which could only reveal average macroscopic information, are unable to elucidate NP-to-NP interactions. Herein, we employ stochastic collision electrochemistry to track the morphology transformation of Ag NPs in photochemical process at the single NP level. By further statistical analysis of time-resolved current transients, we quantitatively determine the dynamic chemical potential difference and interparticle communication between populations of large and small Ag NPs. The high sensitivity of stochastic collision electrochemistry enables the in situ investigation of chemical communication-dependent transformation kinetics of NPs in photochemical process, shedding light on designing nanomaterials.

Selective Hydrogenation of Dimethyl Oxalate to Methyl Glycolate over Boron-Modified Ag/SiO2 Catalysts

The addition of boron (B) as a promoter to the Ag/SiO₂ catalyst for the selective hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG) was investigated. A comparison of the preparation method for incorporation of B found that the addition during the ammonia evaporation deposition-precipitation synthesis of the Ag/SiO₂ catalyst (Ag-B/SiO₂) was inferior to incipient wetness impregnation introduction of the Ag/SiO₂ catalyst (B/Ag/SiO₂). Moreover, the effects of B contents (0.5-5 wt %) on the physicochemical properties and catalytic performance of the B/Ag/SiO₂ catalysts were investigated by XRF, N₂-physisorption, XRD, FTIR, TEM, EDX mapping, H₂-TPR, NH₃-TPD, XPS, and catalytic testing. The results indicated that both the catalytic activity and stability of the Ag/SiO₂ catalyst were noticeably enhanced after the introduction of B. The B/Ag/SiO₂ catalyst with 1 wt % B showed the best catalytic performance of 100% DMO conversion and 88.3% MG selectivity, which could be attributed to the highest dispersion of the active metal and the smallest Ag particle size stabilized by the strong interaction between silver and boron species.

Catalysis of Alloys: Classification, Principles, and Design for a Variety of Materials and Reactions

Alloying has long been used as a promising methodology to improve the catalytic performance of metallic materials. In recent years, the field of alloy catalysis has made remarkable progress with the emergence of a variety of novel alloy materials and their functions. Therefore, a comprehensive disciplinary framework for catalytic chemistry of alloys that provides a cross-sectional understanding of the broad research field is in high demand. In this review, we provide a comprehensive classification of various alloy materials based on metallurgy, thermodynamics, and inorganic chemistry and summarize the roles of alloying in catalysis and its principles with a brief introduction of the historical background of this research field. Furthermore, we explain how each type of alloy can be used as a catalyst material and how to design a functional catalyst for the target reaction by introducing representative case studies. This review includes two approaches, namely, from materials and reactions, to provide a better understanding of the catalytic chemistry of alloys. Our review offers a perspective on this research field and can be used encyclopedically according to the readers' individual interests.

Synthesis of methyl glycolate by hydrogenation of dimethyl oxalate with a P modified Co/SiO2 catalyst

A P-modified Co/SiO₂ catalyst was reported for the first time in the selective hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG) reaction and the synthesized Co₈P/SiO₂ exhibited 94.6% conversion of DMO and 88.1% selectivity to MG during a 300 h continuous test. The doping element of P in the catalyst was indispensable and played an important role in improving the catalytic performance of the Co/SiO₂ catalyst.

Ni-Modified Ag/SiO2 Catalysts for Selective Hydrogenation of Dimethyl Oxalate to Methyl Glycolate

Ni-modified Ag/SiO₂ catalysts containing 0~3 wt.% Ni were obtained by impregnating Ni species onto Ag/SiO₂ followed by calcination and reduction. The catalysts’ performance in the hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG) was tested. Ag-0.5%Ni/SiO₂ showed the highest catalytic activity among these catalysts and exhibited excellent catalytic stability. The effects of the Ni content on the structure and surface chemical states of catalysts were investigated by XRF, N₂-sorption, XRD, TEM, EDX-mapping, FT-IR, H₂-TPR, UV–vis, and XPS. The better catalytic activity and stability of Ni-modified Ag/SiO₂ (versus Ag/SiO₂) are ascribed to the improved dispersion of active Ag species as well as the higher resistance to the growth of Ag particles due to the presence of Ni species.