Template-Mediated Ni(II) Dispersion in Mesoporous SiO₂ for Preparation of Highly Dispersed Ni Catalysts: Influence of Template Type

Abstract

Supported Ni catalysts on three mesoporous SiO supports (i.e., SBA-15, MCM-41, and HMS) were prepared using a solid-state reaction between Ni(NO) and organic template-occluded mesoporous SiO. For comparison, supported Ni catalysts on mesoporous SiO synthesized by the conventional impregnation method were also included. The catalysts were characterized by scanning electron microscopy, X-ray diffraction, UV-vis diffuse reflectance spectroscopy, N adsorption, X-ray photoelectron spectroscopy, H temperature-programmed reduction, transmission electron microscopy, and transmission electron microscopy-energy-dispersive X-ray. The catalytic properties of the catalysts were evaluated using gas-phase catalytic hydrodechlorination of 1,2-dichloroethane. The results showed that upon grinding Ni(NO) with template-occluded mesoporous SiO, strong coordination between Ni and dodecylamine was identified in the Ni(NO)-HMS system. Additionally, the results of H temperature-programmed reduction revealed that NiO in calcined NiO/HMS was reduced at higher temperature than those in calcined NiO/SBA-15 and NiO/MCM-41, reflecting the presence of a strong interaction between NiO and mesoporous SiO in NiO/HMS. Consistently, the average particle sizes of metallic Ni were found to be 2.7, 3.4, and 9.6 nm in H-reduced Ni/HMS, Ni/SBA-15, and Ni/MCM-41, respectively, indicative of a much higher Ni dispersion in Ni/HMS. For the catalytic hydrodechlorination of 1,2-dichloroethane, Ni/MCM-41 synthesized by the solid-state reaction method exhibited a catalytic activity similar to that prepared by the impregnation method, while higher catalytic activities were observed on Ni/HMS and Ni/SBA-15 than on their counterparts prepared by the impregnation method. Furthermore, a higher conversion was identified on Ni/HMS than on Ni/SBA-15 and Ni/MCM-41, highlighting the importance of template type for the preparation of highly dispersed metal catalysts on mesoporous SiO.

Micro- and mesoporous supports for CO2 methanation catalysts: A comparison between SBA-15, MCM-41 and USY zeolite

“…Finally, the band gaps of NiO calculated from DRS UV-Vis data were compared to the Ni 0 sizes determined by TEM for the Ni-based catalysts ( Table 3). As reported 47,48 , Ni species size can influence the band gap, since the bigger the particles, the higher the amount of defects and/or vacancies present in the intergranular regions able to generate new energy levels responsible for the reduction of the band gap. Indeed, the results obtained for the samples of the present study confirm the relationship between the Ni 0 sizes and the calculated band gaps for NiO, indicating that the use of different supports influence the electronic properties of the Ni species.…”

Accelerated active phase transformation of NiO powered by Pt single atoms for enhanced oxygen evolution reaction

“…S1 and S2 † ). 35 , 36 Bulk Pt doped NiO nanocubes were obtained by impregnation, drying and calcination in air, and template removal via NaOH etching, and the nominal Pt loading amount was 0.5 wt%. Such an impregnation & calcination process can be consistently and cost-effectively up-scaled.…”

Functionalized Ordered Mesoporous Silicas (MCM-41): Synthesis and Applications in Catalysis

“…As a result, the template-containing catalyst displayed a higher catalytic activity, probably due to the presence of strong basic sites, which lead to a major grafting of metal nanoparticles within the silica matrix. Zheng et al [120], studied the same effect in a catalysis for the hydrodechlorination of 1,2-dicholoethane. By contrast to the later report, these authors reported that the strong electrostatic repulsive interactions between Ni (II) and CTAB lead to aggregation of Ni nanoparticles upon calcination resulting in a low dispersion of the nickel source (Ni(NO 3 ) 2 ) into the mesopores of MCM-41.…”