Anti‐Coking Ni/SiO₂ Catalyst for Dry Reforming of Methane: Role of Oleylamine/Oleic Acid Organic Pair

Abstract

We demonstrate the synthesis of silica‐supported Ni catalyst in the presence of oleylamine (OAm) and oleic acid (OAc) as the ligand and surfactant. Compared with OAm or OAc alone, Ni/SiO2 prepared with OAm/OAc organic pair showed a much smaller Ni particle, a much stronger metal–support interaction (MSI), an enhanced initial conversion of both CO2 and CH4 and a prolonged stability over 16 h with zero carbon deposition. How the OAm/OAc organic pair affects the catalyst formation mechanism is proposed: OAc intimately interacts with silica by hydrogen bond formed between the carboxylic group and silanol group; OAm forms a complex with Ni and promotes the adsorption of Ni on silica through the basic property of amine ligand; amide formation between the carboxylic group of OAc and the amine group of OAm makes use of both additives; in addition, a stronger steric hindrance is given by the more complex aliphatic chain network of the pair, retarding the growth of Ni particles.

Sandwich‐Like Silica@Ni@Silica Multicore–Shell Catalyst for the Low‐Temperature Dry Reforming of Methane: Confinement Effect Against Carbon Formation

“…The reducibility of catalysts was examined by using temperature‐programmed reduction (TPR; Figure ). All the catalysts show two reduction peaks; one in the relatively low temperature range of 540–580 °C, which is usually attributed to the reduction of Ni 2+ species that interact weakly with the support, mainly NiO in our case . The other is at a high temperature of 750–780 °C, which could be assigned to the reduction of Ni 2+ species in the PS phase with a strong metal–support interaction .…”

Ni-Silica-based Catalysts for CH4 Reforming by CO2 with Enhanced Stability: Recent Designs and the Impacts of Ni Confinement, Promoters, and Core-Shell Structures

“…Organic additives may also be useful in this regard. Gao et al (Table 1, entry 15) [42] prepared 5% Ni/SiO 2 catalysts promoted with oleylamine (OAm) and/or oleic acid (OAc) using an incipient wetness impregnation method. In this approach, OAm and/or OAc were used as surfactants, ligands, and/or reducing agents added on purpose to the solution of nickel nitrate prior to the impregnation in order to improve the dispersion of Ni on silica due to the strong interaction of the Ni precursors with OAm and OAc.…”

“…In this approach, OAm and/or OAc were used as surfactants, ligands, and/or reducing agents added on purpose to the solution of nickel nitrate prior to the impregnation in order to improve the dispersion of Ni on silica due to the strong interaction of the Ni precursors with OAm and OAc. Using a mixture of OAm and OAc with the spheres of mesoporous silica (particles size = 40-60 mm, specific surface area = 753 m 2 g -1 , mean pore size = 7.5 nm) produced, after calcination, small NiO particles in the Ni/SiO 2 -OAmc material, and therefore, after reduction by H 2 , to small Ni 0 NPs (Table 1, entries 5, 15) [32,42]. Using this approach, the authors managed to achieve 5% Ni/silica with a nickel dispersion of c.a.…”

From Colloidal Monodisperse Nickel Nanoparticles to Well-Defined Ni/Al2O3 Model Catalysts

“…Oleic acid is one of the most frequently applied surfactants for colloidal NP synthesis, also used in impregnation protocols for the preparation of supported NPs. [10][11] In the case of Ni-based colloidal synthesis, several protocols have been reported wherein oleic acid is used either solely or in combination with other (excluding P-containing) surfactants. [12][13][14][15][16] None of these works achieved particle size control in the 1-10 nm range.…”