Insights into the Zn Promoter for Improvement of Ni/SiO₂ Catalysts Prepared by the Ammonia Evaporation Method toward CO₂ Methanation

Abstract

As a pure combustible gas with a high calorific value, methane has long been favored, and that is why the CO2 methanation reaction is attracting more and more attention. However, it is still challenging for this reaction due to the chemical inertness of CO2 molecules, poor reaction efficiency at low temperatures, catalyst sintering at high temperatures, and carbon monoxide toxicity. Herein, the ammonia evaporation method was utilized to synthesize a series of Zn-modified Ni/SiO2 catalysts with high surface area and high dispersity of active metals. The 80Ni-Zn/SiO2 catalyst with an appropriate Ni/Zn molar ratio of 80:1 exhibited a high-performance breakthrough with a CO2 conversion greater than 80% at 300 °C, good stability for 40 h at 310 °C, and a gas hourly space velocity of 18,000 mL·g–1·h–1. These catalysts were further characterized by using a series of methods like in situ diffuse reflectance infrared Fourier transform spectroscopy to investigate the structural properties and potential reaction pathways. The effect of the Zn promoter on the Ni/SiO2 catalyst for CO2 methanation has been well investigated, namely, improving Ni dispersion and enhancing the H2 adsorption. The findings demonstrate the broad availability, affordability, and remarkable high-performance practicability of the raw ingredients for the production of Ni-based catalysts for commercial applications.

Enhanced CO2 Methanation over Ni/Na-HNTs: Effect of Pretreatment with NaOH

“… a Obtained from H 2 -TPR peak analysis. b Ni dispersion determined by H 2 -pulse chemisorption analysis. c T O F .25em ( normals − 1 ) = R normalC normalO 2 D N i , calculated at 275 °C. R C O 2 and D Ni are the CO 2 consumption rate and Ni dispersion, respectively. , …”

“… c T O F .25em ( normals − 1 ) = R normalC normalO 2 D N i , calculated at 275 °C. R C O 2 and D Ni are the CO 2 consumption rate and Ni dispersion, respectively. , …”

“…c = TOF (s ) 275 °C. R CO 2 and D Ni are the CO 2 consumption rate and Ni dispersion, respectively 15,46.…”

Effects of Organic Compounds on Ni/AlLaCe Catalysts for Ammonia Decomposition to Hydrogen

“…The first group consists of supported noble metal catalysts, Ru-based catalyst that is currently being reported demonstrates exceptional catalytic performance at low temperatures, − but large-scale applications of noble metal are difficult due to the high cost and scarcity. The second one is the common metal catalysts, such as Ni, − Fe, − Co. − Ganley et al compared several monometallic catalysts loaded on alumina and concluded by comparing the ammonia decomposition activities: Ru > Ni > Rh > Co > Ir > Fe > Pt > Cr > Pd > Cu > Te, Se, Pb …”

Defect-Rich and Boron-Doped Al2O3-Supported Ru Nanocatalyst for Enhanced CO2 Methanation Activity

“…As is known to all, fossil fuels will still continue to occupy an important position in the energy and source supply in the foreseeable future. Therefore, the topic of reducing the emission of CO 2 and finding effective strategies for carbon capture and utilization of CO 2 always attracts more and more attention. − Specifically, through chemical, biological, photochemical, or electrochemical pathways, CO 2 may be converted into various value-added chemicals (e.g., alcohols, alkenes, alkanes, and aromatics) and fuels. − For CO 2 conversion, catalytic CO 2 hydrogenation to produce methane is a desirable pathway because methane can be used as a storage fuel with several advantages, such as low storage cost, convenient transportation, and high energy density. , At present, supported precious metal (e.g., Ru, Pd, Pt − ) and nonprecious metal (e.g., Ni, Fe − ) catalysts have been widely explored in CO 2 methanation. Especially, supported Ru catalysts over oxide or nonoxide supports exhibited good catalytic methanation activity, − thanks to their strong ability for dissociating hydrogen and relatively low apparent activation energy (68–80 kJ·mol –1 ) .…”