Tuned acidity in zeotypes: A descriptor to unravel the direct conversion of methane to methanol?
Doktorsavhandling, 2020
In this study, Al, B, Fe, Ga, and Ti are incorporated in the MFI framework of silicalite zeotypes. The zeotype crystallites are imaged with scanning and transmission electron microscopy, and the MFI framework structure is characterized with X-ray diffraction, nitrogen sorption and Raman spectroscopy. The process from the as synthesized samples to the corresponding materials in the acid form is examined with in situ infrared spectroscopy, with and without ammonia and nitric oxide as probe molecules. Furthermore, the following series of increasing acidity is observed by means of infrared spectroscopy: 0 = pure silicalite = Ti-silicalite < B-silicalite < Fe-silicalite < Ga-silicalite < Al-silicalite.
The influence of the zeotype acidity during methane exposure and temperature programmed desorption of methanol has been investigated in situ with infrared spectroscopy. The results show that the presence of iron promotes methane activation and that methanol is more strongly bound to the zeotype in the presence of stronger acid sites. Because methane activation and methanol extraction are two of the key steps in the direct conversion of methane to methanol, our results indicate that Al-free zeotypes with tuned acidity pinpoint important catalyst design parameters needed for this reaction.
methane
methanol
zeotype
catalysis
MFI
zeolite
infrared spectroscopy
Författare
Simone Creci
Chalmers, Kemi och kemiteknik, Tillämpad kemi, Polymerteknologi
Tuned Acidity for Catalytic Reactions: Synthesis and Characterization of Fe- and Al-MFI Zeotypes
Topics in Catalysis,; (2019)
Artikel i vetenskaplig tidskrift
Local anisotropy in single crystals of zeotypes with the MFI framework structure evidenced by polarised Raman spectroscopy
Physical Chemistry Chemical Physics,; Vol. 22(2020)p. 1640-1654
Artikel i vetenskaplig tidskrift
Methoxy ad-species in MFI zeotypes during methane exposure and methanol desorption followed by in situ IR spectroscopy
Catalysis Today,; Vol. In Press(2020)
Artikel i vetenskaplig tidskrift
Simone Creci, Anna Martinelli, Szilvia Vavra, Per-Anders Carlsson and Magnus Skoglundh - Acidity as descriptor for methanol desorption in B-, Ga- and Ti-MFI zeotypes
Ämneskategorier
Materialteknik
Kemiteknik
Annan naturvetenskap
Infrastruktur
Chalmers materialanalyslaboratorium
Styrkeområden
Materialvetenskap
ISBN
978-91-7905-422-9
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4889
Utgivare
Chalmers tekniska högskola
Opponent: Unni Olsbye, University of Oslo, Norway