Preparation of Mesoporous Ni–alumina Catalyst by One-step Sol–gel Method: Control of Textural Properties and Catalytic Application to the Hydrodechlorination of o-dichlorobenzene

Abstract

Mesoporous Ni-alumina catalysts (Ni-alumina-pre and Ni-alumina-post) were synthesized by one-step sol-gel method using micelle complex comprising lauric acid and nickel ion as a template with metal source and using aluminum sec-butoxide as an aluminum source. The Ni-alumina catalysts showed relatively high surface areas (303 m 2 /g for Ni-alumina-pre and 331 m 2 /g for Ni-alumina-post) and narrow pore size distributions centered at ca. 4 nm. Highly dispersed Ni particles were observed in the Nialumina catalysts (ca. 5.2 nm for Ni-alumina-pre and ca. 6.8 nm for Ni-alumina-post) after reduction at 550°C, while a catalyst prepared without a template (NiAl-comp) exhibited inferior porosity with large metal particles (ca. 12.3 nm). Mesoporous Nialumina catalysts with different porosity were obtained by employing different hydrolysis step of aluminum source. When aluminum source was hydrolyzed under the presence of micelle complex, a supported Ni catalyst with highly developed framework mesoporosity was obtained (Ni-alumina-post). On the other hand, when aluminum source was pre-hydrolyzed followed by mixing with micelle solution, the resulting catalyst (Ni-alumina-pre) retained high portion of textural porosity. It was revealed that the hydrolysis method employed in this research affected not only textural properties but also metal-support interaction in the Nialumina catalysts. It was also found that the Ni-alumina-pre catalyst exhibited weaker interaction between nickel and alumina than the Ni-alumina-post, leading to higher degree of reduction in the Ni-alumina-pre catalyst. In the hydrodechlorination of o-dichlorobenzene, the Ni-alumina catalysts exhibited better catalytic performance than the NiAl-comp catalyst, which was attributed to higher metal dispersion in the Ni-alumina catalysts. In particular, the Ni-alumina-pre catalyst showing 1.5 times higher degree of reduction and larger amounts of o-dichlorobenzene adsorption exhibited better catalytic performance than the Nialumina-post catalyst.

The influence of nickel loading on reducibility of NiO/Al₂O₃ catalysts synthesized by sol-gel method

“…These peaks were attributed to the reduction of bulk NiO species with different extent interactions with the support. The second set appeared around 800 • C (high temperature reduction peak) corresponding to the reduction of NiAl 2 O 4 phases [20,21]. The XRD patterns of these samples showed no diffraction peaks corresponding to the presence of NiO species.…”

Hydrogenation of Liquid Styrene by Alumina Supported Nickel Catalysts: Comparison between Classical and Non-Classical Methods

“…It can be seen that the 13.8wt% Ni-Al 2 O 3 /C exhibits a strong peak at 400 K. According to Kim and co-workers [14], this peak can be attributed to bulk oxides which do not interact with the support. The availability of higher Ni content in this catalyst enabled the growth of the particles, which increased the size of particles [14,15]. This can result in a weaker interaction between the oxide particles with the support.…”

Preparation of nickel-mesoporous materials and their application to the hydrodechlorination of chlorinated organic compounds

“…It has been claimed that the textural porosity, resulting from void spaces between primary particles, would favor the introduction of a reactant into the framework pores, leading to facile diffusion of reactant onto the active sites [49][50][51][52][53][54]. We successfully prepared mesoporous Ni-Alumina catalysts by a one-step sol-gel method [55] and controlled their textural properties by employing different hydrolysis methods [56]. [5].…”

“…The hydrodechlorination reaction was conducted at 300°C after reduction with a mixed stream of H 2 (20 ml/min) and N 2 (20 ml/min) at 500°C for 2 h. W/F = 0.645 g-cat h/liter. Figure 4 shows the schematic procedure for the preparation of mesoporous Ni-Alumina catalysts by a one-step sol-gel method [56]. The prepared catalysts were denoted as Ni-Alumina-post and Ni-Alumina-pre, according to the hydrolysis step used (post-hydrolysis and pre-hydrolysis).…”

“…The catalytic activities of Ni-Alumina-pre, Ni-Alumina-post, and NiAl catalysts in the hydrodechlorination of o-dichlorobenzene (DCB) are summarized in Table 1 [56]. HCl, chlorobenzene, and benzene were produced in the hydrodechlorination of o-dichlorobenzene (DCB).…”