New insights on the effect of the H2/CO ratio for enhancement of CO methanation over metal-free fibrous silica ZSM-5: Thermodynamic and mechanistic studies

I. Hussain, A. A. Jalil*, C. R. Mamat, T. J. Siang, A. F.A. Rahman, M. S. Azami, R. H. Adnan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

54 Scopus citations

Abstract

Thermodynamic and experimental facts of CO methanation were conducted by the Gibbs energy minimization method to produce substituted natural gas (SNG). The microemulsion technique was used to synthesized metal-free fibrous silica ZSM-5 (FSZSM-5) to compare with the catalytic activity results with the thermodynamic results. The catalysts were characterized by FESEM, TEM, XRD, BET, FTIR, and ESR. While spent catalysts were evaluated by TGA/DTA, TEM, EDX, and Raman spectra to study the change in morphology and carbon deposition. In-situ FTIR spectroscopy was used to investigate the possible reaction mechanism. The FSZSM-5 was proved the best catalyst than ZSM-5 due to unique fibrous morphology, high BET surface area (610 m2/g), high basicity, and extensive oxygen vacancies. The FSZSM-5 exhibited a higher CO methanation activity of 56% CO conversion and 78% CH4 selectivity using H2/CO = 5:1 at 450 °C. Increasing the H2: CO ratio favored methanation activity to produce CH4 and to resist carbon deposition in the following order: 5:1 > 3:1 > 2:1 > 1:1. Furthermore, the in-situ FTIR results supported the proposal that the dissociation of linear adsorbed CO over oxygen vacancies appeared to control the rate of CH4 formation by hydrogenation of adsorbed C*. These results will be beneficial to understand better and optimize the CO methanation reaction process in the preparation of highly active catalysts for SNG production.

Original languageEnglish
Article number112056
JournalEnergy Conversion and Management
Volume199
DOIs
StatePublished - 1 Nov 2019
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2019 Elsevier Ltd

Keywords

  • Effect of H/CO ratio
  • Enhancement of CO methanation
  • Mechanistic insights
  • Metal-free fibrous silica ZSM-5
  • Thermodynamics

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Nuclear Energy and Engineering
  • Fuel Technology
  • Energy Engineering and Power Technology

Fingerprint

Dive into the research topics of 'New insights on the effect of the H2/CO ratio for enhancement of CO methanation over metal-free fibrous silica ZSM-5: Thermodynamic and mechanistic studies'. Together they form a unique fingerprint.

Cite this