Effect of Nickel Nanocatalyst Loading on Supercritical Water Gasification of Coconut Shell

Impregnation of metal catalysts into biomass before thermochemical conversion may provide benefits of increased selective reactivity to obtain desirable products. In this work, coconut shells impregnated with increasing loadings of nickel were successfully prepared using a room-temperature impregnat...

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Bibliographic Details
Published in:Energies (Basel) 2024-02, Vol.17 (4), p.872
Main Authors: Marcelino, Marcela, Leeke, Gary, Jiang, Guozhan, Onwudili, Jude, Alves, Carine, de Sousa, Ana, de Santana, Delano, Torres, Felipe, de Melo, Silvio, Torres, Ednildo
Format: Article
Language:English
Subjects:
Aqueous solutions
Biomass
Carbon dioxide
Catalysts
Climate change
coconut shell
Efficiency
Energy
Gases
Global temperature changes
Hydrogenation
Influence
Lignin
Nanoparticles
Natural gas
Nickel
nickel loading
Nitrates
Organic chemicals
Scanning electron microscopy
Spectrum analysis
supercritical water gasification
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Summary:Impregnation of metal catalysts into biomass before thermochemical conversion may provide benefits of increased selective reactivity to obtain desirable products. In this work, coconut shells impregnated with increasing loadings of nickel were successfully prepared using a room-temperature impregnation method using a nickel salt solution at 1 and 2 molar (M) concentrations. The physicochemical characterization of the 2 M impregnated sample revealed the presence of 5.6 wt% of nickel with a particle size of 13.5 nm. The nickel-impregnated samples’ supercritical water gasification (SCWG) was conducted with biomass loading ranging from 20 wt% to 30 wt%, at temperatures between 400 °C and 500 °C, and residence times from 20 to 60 min. Higher nickel loading, higher temperatures and longer reaction times promoted the production of H2 and CO2 up to 15 and 79 mol%. Higher nickel loading also led to an increased Hydrogen Gasification Efficiency value of up to 133%. The analysis of hydrochars suggested that increasing nickel loading enhanced the reduction in nickel ions to the Ni0 nanoparticles, leading to higher H2. Additionally, the chemical composition of the liquid product showed the significant ability of nickel to promote lignin decomposition into phenol, facilitating the phenol hydrogenation reaction and subsequent gas production.
ISSN:1996-1073
1996-1073
DOI:10.3390/en17040872