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Zirconium‐based intermetallics as heterogeneous catalysts for the fischer‐tropsch reaction: II. Zr‐Ni‐Cu catalysts
Author(s) -
AlShammary A. F. Y.,
Caga I. T.,
Tata A. Y.,
Winterbottom J. M.,
Harris I. R.
Publication year - 1992
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.280550411
Subject(s) - catalysis , intermetallic , copper , fischer–tropsch process , alloy , nickel , zirconium , methane , hydrogen , hydrocarbon , selectivity , materials science , chemistry , metallurgy , inorganic chemistry , organic chemistry
Abstract Intermetallic alloys of the general formula Zr 50 Ni x Cu 50‐x (where 0 ⩽ × ⩽ 50) were prepared by argon arc melting and powdered by hydrogen decrepitation. These materials were used as catalysts for the H 2 /CO reaction in the temperature range 300–400°C, in the pressure range 1–9 barg and for H 2 /CO ratios in the range 1 to 5. Derived catalysts were prepared by air treatment of the hydrided alloys and were subjected to identical investigations to the latter. The hydrided and derived catalysts behaved in a very similar manner in terms of selectivity, which increased with respect to higher hydrocarbon production with (i) increasing total pressure, (ii) decreasing values of H 2 /CO and (iii) increasing copper to the extent where CH 4 contents was < 50% of the products. Increased temperature gave rise to increasing methane production. The activity of the alloy system exhibited a sharp activity maximum at the nickel‐rich end of the series and the copper‐rich alloys were almost ten times less active. The initial rate equation was observed to be of the form:\documentclass{article}\pagestyle{empty}\begin{document}$$ r = k\,p_{H_2 }^m p_{CO}^n $$\end{document}However, whereas n = 0, m varied between 0.5 and 1.2 for both series of catalysts. The presence of copper promotes the formation of higher hydrocarbons, especially the formation of ethene. It is presumed that the presence of copper at the surface inhibits the polyerization of CH X species and favours the CO insertion.