Investigation of coke formation on Ni-Mg-Al catalyst for hydrogen production from the catalytic steam pyrolysis-gasification of polypropylene

Chunfei Wu, Paul T. Williams*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

87 Citations (Scopus)

Abstract

Co-precipitated Ni-Mg-Al catalyst was prepared and investigated in relation to the production of hydrogen from the catalytic steam pyrolysis-gasification of polypropylene using a two-stage reaction system. Coke formation on the Ni-Mg-Al catalyst was investigated by using temperature-programmed oxidation (TPO), X-ray diffraction (XRD), scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDXS), transmission electron microscopy (TEM) and focused ion beam (FIB)/scanning electron microscopy (SEM). The coke formation mechanism on the Ni-Mg-Al catalyst is proposed. It is suggested that the Ni-Mg-Al catalyst is initially reduced during the gasification process, the reactions of decomposition/reforming of hydrocarbons gases occur on the surface and inside the catalyst; this resulted in partial fragmentation of the catalyst into small particles. Layered carbons, perhaps containing monoatomic carbon, metal carbides, etc., are suggested to be a transition layer for the formation of filamentous carbons. The addition of Mg into the Ni-Al catalyst was found to increase the catalytic activity and the physical stability of catalyst. In addition, increasing the calcination temperature from 750 to 850 °C reduced the surface area of the fresh Ni-Mg-Al catalyst, increased the NiO crystal size, and resulted in a decrease of catalytic activity in the pyrolysis-gasification of polypropylene; however, a more stable catalyst was obtained with higher calcination temperature.

Original languageEnglish
Pages (from-to)198-207
Number of pages10
JournalApplied Catalysis B: Environmental
Volume96
Issue number1-2
DOIs
Publication statusPublished - 26 Apr 2010
Externally publishedYes

Keywords

  • Catalyst
  • Coke
  • Gasification
  • Magnesium
  • Nickel
  • Polypropylene

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology
  • Environmental Science(all)

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