Ni–Zn–Al-Based Oxide/Spinel Nanostructures for High Performance, Methane-Selective CO2 Hydrogenation Reactions

Abstract

In the present study, NiO modified ZnAl 2 O 4 and ZnO modified NiAl 2 O 4 spinel along with pure Al 2 O 3 , ZnAl 2 O 4 and NiAl 2 O 4 for comparison in the CO 2 hydrogenation reaction have been investigated. It was found that NiAl 2 O 4 , NiO/ZnAl 2 O 4 and ZnO/NiAl 2 O 4 catalysts exhibited outstanding activity and selectivity towards methane even at high temperature compared to similar spinel structures reported in the literature. NiO/ZnAl 2 O 4 catalyst showed CO 2 consumption rate of ~ 19 μmol/g·s at 600 °C and ~ 85% as well as ~ 50% of methane selectivity at 450 °C and 600 °C, respectively. The high activity and selectivity of methane can be attributed to the presence of metallic Ni and Ni/NiO/ZnAl 2 O 4 interface under the reaction conditions as evidenced by the XRD results.

Mixed Oxides NiO/ZnO/Al2O3 Synthesized in a Single Step via Ultrasonic Spray Pyrolysis (USP) Method

“…and ZnAl2O4 supports, respectively, or a possible overlap with the supports' diffraction peaks [41].…”

“…This indicated that spinel in obtained nanocomposites was non-stoichiometric.When the reaction temperature was increasing, the diffraction peaks of the samples were slightly expanded (Figure4). For NiAl 2 O 4 and ZnAl 2 O 4 samples, no peak characteristics of NiO and ZnO were seen, indicating the fine dispersion of these species on the NiAl 2 O 4 and ZnAl 2 O 4 supports, respectively, or a possible overlap with the supports' diffraction peaks[41].…”

Rational Design of Catalysts with Spinel Nanostructures for Thermal-Driven C1 Conversion

“…The strong interaction between Ni and spinel oxide supports could improve the dispersion of Ni particles and thus construct more metal−support interfaces. Park et al 125 developed MgAl 2 O 4 -and MnAl 2 O 4 -supported Ni catalysts, where Ni functioned as the H 2 dissociation site. The outstanding performance of methanation was due to the enhanced synergic effect of moderate basic sites and well-dispersed metallic Ni.…”

CO2 Conversion on N-Doped Carbon Catalysts via Thermo- and Electrocatalysis: Role of C–NOx Moieties

“… 11 − 13 The proper combination of reducible oxides with nonprecious metals or spinel structures can also lead to CH 4 formation during the CO 2 hydrogenation. 14 , 15 In the synthesis of methanol, mainly Cu and Cu-Zn oxide based catalysts are employed. 16 Producing long-chain hydrocarbons is also in the focus of research, typically employing tandem catalysts.…”

“…supported on semiconducting oxides (TiO 2 , CeO 2 , etc.) at ambient pressures. − The proper combination of reducible oxides with nonprecious metals or spinel structures can also lead to CH 4 formation during the CO 2 hydrogenation. , In the synthesis of methanol, mainly Cu and Cu-Zn oxide based catalysts are employed . Producing long-chain hydrocarbons is also in the focus of research, typically employing tandem catalysts. − In the EC CO 2 R, the most selective CO-producing catalysts are Au and Ag, − while formic acid is mostly obtained on Sn-based materials. , Cu is unique in this sense, being the only metal capable of forming alcohols and hydrocarbons with reasonable rates. − …”