Size-Tunable Ni Nanoparticles Supported on Surface-Modified, Cage-Type Mesoporous Silica as Highly Active Catalysts for CO₂ Hydrogenation

Abstract

In this study, ultrasmall Ni nanoparticles (Ni NPs) were controllably supported in the cage-type mesopores of −COOH-functionalized mesoporous silica SBA-16 (denoted as Ni­(x)@S16C, where x is the Ni loading) via wet impregnation under alkaline conditions, followed by thermal reduction. The particle sizes of the Ni NPs ranged from 2.7 to 4.7 nm, depending on the Ni loading. Under the appropriate alkaline conditions (i.e., pH 9) deprotonation of the carboxylic acid groups on the cage-type mesopore surfaces endowed the effective incorporation of Ni2+ precursors via favorable electrostatic interactions, and thus well-dispersed Ni NPs confined in the cage-type mesopores of SBA-16 were achieved. The combination of the cage-type mesopores and the surface functionality provided dual beneficial features to confine the immobilized Ni NPs and to tune their particle sizes. The remarkably enhanced catalytic activities of the Ni­(x)@S16C materials for CO2 hydrogenation and CH4 formation were demonstrated. The cage-type SBA-16 support provided a positive effect for the Ni NPs to enrich the surface sites, which can strongly adsorb CO and CO2, thus leading to high catalytic rates for CO2 and CO hydrogenation. The reaction mechanism, catalytic kinetics, and active sites were investigated to correlate to the high reaction rate for CO2 hydrogenation to form CH4.

Highly Loaded Mesoporous Ni–La2O3 Catalyst Prepared by Colloidal Solution Combustion Method for CO2 Methanation

“…Catalysts 2019, 9, x FOR PEER REVIEW 2 of 11 surface area, such as mesoporous silica [16][17][18]. However, the metal loading of a catalyst prepared using this method is low, and usually not higher than 30 wt %.…”

“…To increase the low-temperature activity of Ni-based catalysts, many methods have been proposed for preparing catalysts with a small Ni particle size [15]. A general strategy for increasing the dispersion of active components involves loading the active component on a carrier with a high surface area, such as mesoporous silica [16][17][18]. However, the metal loading of a catalyst prepared using this method is low, and usually not higher than 30 wt %.…”

A novel Core–Shell structured CuIn@SiO2 catalyst for CO2 hydrogenation to methanol

“…Hence, low‐cost, highly efficient and sustainable catalysts for methanol synthesis are required to better utilize CO 2 . Metallic Cu, Co, and Ni are widely used as the active species for CO 2 hydrogenation reaction and Cu is especially more beneficial for methanol formation from CO 2 hydrogenation than Co and Ni . However, the catalytic activity of a pure copper catalyst is almost negligible.…”

Structure sensitivity in CO2 methanation over CeO2 supported metal catalysts

“…Whereas, increasing turnover frequencies were observed with increasing Fe particle size for CO hydrogenation (97). Particle size effect of SiO2 supported Ni catalysts on CO2 methanation is also discussed recently (15,98). Vogt et al (15) reported maximum TOF for 2.5nm Ni catalysts, while Chen et.…”

“…al. (98) shows decreasing activity from 2.4 to 4.7nm. Interestingly, both report the highest CO2 methanation activity for catalysts with ~2.4nm particle size.…”