A Systematic Study of Isomorphically Substituted H-MAlPO-5 Materials for the Methanol-to-Hydrocarbons Reaction.
Chemphyschem
; 19(4): 484-495, 2018 Feb 19.
Article
em En
| MEDLINE
| ID: mdl-29250897
ABSTRACT
Substituting metals for either aluminum or phosphorus in crystalline, microporous aluminophosphates creates Brønsted acid sites, which are well known to catalyze several key reactions, including the methanol to hydrocarbons (MTH) reaction. In this work, we synthesized a series of metal-substituted aluminophosphates with AFI topology that differed primarily in their acid strength and that spanned a predicted range from high Brønsted acidity (H-MgAlPO-5, H-CoAlPO-5, and H-ZnAlPO-5) to medium acidity (H-SAPO-5) and low acidity (H-TiAlPO-5 and H-ZrAlPO-5). The synthesis was aimed to produce materials with homogenous properties (e.g. morphology, crystallite size, acid-site density, and surface area) to isolate the influence of metal substitution. This was verified by extensive characterization. The materials were tested in the MTH reaction at 450 °C by using dimethyl ether (DME) as feed. A clear activity difference was found, for which the predicted stronger acids converted DME significantly faster than the medium and weak Brønsted acidic materials. Furthermore, the stronger Brønsted acids (Mg, Co and Zn) produced more light alkenes than the weaker acids. The weaker acids, especially H-SAPO-5, produced more aromatics and alkanes, which indicates that the relative rates of competing reactions change upon decreasing the acid strength.
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1
Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Chemphyschem
Assunto da revista:
BIOFISICA
/
QUIMICA
Ano de publicação:
2018
Tipo de documento:
Article
País de afiliação:
Noruega