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

Marcela M. Marcelino, Gary A. Leeke, Guozhan Jiang, Jude A. Onwudili, Carine Tondo Alves, Ana Luiza F. de Sousa, Delano M. de Santana, Felipe A. Torres, Silvio A. B. Vieira de Melo, Ednildo A. Torres

Research output: Contribution to journalArticlepeer-review


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.
Original languageEnglish
Article number872
Number of pages26
Issue number4
Early online date13 Feb 2024
Publication statusPublished - 13 Feb 2024

Bibliographical note

Copyright © 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

Data Access Statement

The authors confirm that the data supporting the findings of this study are available within the article.


  • coconut shell
  • supercritical water gasification
  • nickel loading


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