Highly Dispersed Ni Nanocatalysts Derived from NiMnAl-Hydrotalcites as High-Performing Catalyst for Low-Temperature Syngas Methanation

Abstract

Increasing the low-temperature performance of nickel-based catalysts in syngas methanation is critical but very challenging, because at low temperatures there is high concentration of CO on the catalyst surface, causing formation of nickel carbonyl with metallic Ni and further catalyst deactivation. Herein, we have prepared highly dispersed Ni nanocatalysts by in situ reduction of NiMnAl-layered double hydroxides (NiMnAl-LDHs) and applied them to syngas methanation. The synthesized Ni nanocatalysts maintained the nanosheet structure of the LDHs, in which Ni particles were decorated with MnOy species and embedded in the AlOx nanosheets. It was observed that the Ni nanocatalysts exhibited markedly better low-temperature performance than commercial catalysts in the syngas methanation. At 250 °C, 3.0 MPa and a high weight hourly space velocity (WHSV) of 30,000 mL·g−1·h−1, both the CO conversion and the CH4 selectivity reached 100% over the former, while those over the commercial catalyst were only 14% and 76%, respectively. Furthermore, this NiMnAl catalyst exhibited strong anti-carbon and anti-sintering properties at high temperatures. The enhanced low-temperature performance and high-temperature stability originated from the promotion effect of MnOy and the embedding effect of AlOx in the catalyst.

Improved Water–Gas Shift Performance of Au/NiAl LDHs Nanostructured Catalysts via CeO2 Addition

“…The review of the O 1s photoelectron regions after the curve fitting ( Figure 12 ) shows that the spectra of the as-prepared catalysts consist of two components, namely, less intense low energy peaks centered between 529.3 and 529.7 eV and more intense higher energy peaks between 531.1 and 531.7 eV ( Table 7 ). The low energy peaks are attributed to lattice oxygen named as O I associated with the NiAl layered structure [ 81 , 85 ] and oxygen in the CeO 2 lattice [ 86 , 87 , 88 ] in 3CeNiAl and Au/3CeNiAl samples. The high energy peaks recognized as surface adsorbed oxygen are named O II .…”

“…Genty et al stated [ 89 ] that the mobility of surface oxygen species plays an important role in the catalytic activity in oxidation reactions. The oxygen vacancies are important for the adsorption of oxygen species [ 85 ] from H 2 O vapor in the case of WGS reaction. In this connection, the number of oxygen vacancies in the spent catalysts are calculated by the integrated area ratios of O II /(O II + O I ) ( Table 7 ) by analogy to Lu et al [ 85 ].…”

La2O3‐Promoted Ni/Al2O3 Catalyst for CO Methanation: Enhanced Catalytic Activity and Stability

“…Figure is the X‐ray diffraction (XRD) patterns of the reduced catalysts. For 20NA, the three diffraction peaks at 44.7, 52.1, and 76.4° are the characteristic peaks of γ ‐Al 2 O 3 (JCPDS 00‐034‐0493), and the three diffraction peaks at 34.4, 45.9, and 67.0° are attributed to (111), (200), and (220) planes of metallic Ni (JCPDS 01‐070‐1849) . No diffraction peak of La 2 O 3 is observed on the XRD patterns of 20NA x L and 20NA1L‐Im, indicating that La 2 O 3 species disperse highly on the surface of the catalysts.…”

Perovskite LaNiO3 Nanocrystals inside Mesostructured Cellular Foam Silica: High Catalytic Activity and Stability for CO2 Methanation

“…Carbon dioxide (CO 2 ) is a well‐known greenhouse gas that can also be used as a zero‐ or even negative‐cost carbon feedstock in the production of valuable chemicals and fuels . CO 2 has been mainly converted to fuel and energy carriers such as methane, methanol, dimethyl carbonate, and dimethyl ether due to increasing demand of energy source . Among them, conversion of CO 2 to methane by the reduction of CO 2 via the Sabatier reaction (CO 2 + 4H 2 → CH 4 + 2H 2 O, ΔH = −165.0 kJ mol −1 ) is the most advantageous reaction with respect to thermodynamics, as CO 2 methanation reaction is considerably faster than other reactions of forming alcohols or hydrocarbons …”