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Control of the product distribution in the hydrogenation of vegetable oils over nickel on silica catalysts
Author(s) -
GonzálezMarcos M. Pilar,
GutiérrezOrtiz José I.,
De Elguea Cristina GonzálezOrtiz,
Alvarez Jon I.,
GonzálezVelasco Juan R.
Publication year - 1998
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450760510
Subject(s) - nickel , catalysis , selectivity , product distribution , diffusion , sunflower oil , mass transfer , precipitation , chemistry , kinetic energy , chemical engineering , materials science , inorganic chemistry , organic chemistry , chromatography , thermodynamics , biochemistry , physics , quantum mechanics , meteorology , engineering
Several nickel on silica catalysts, prepared by impregnation or precipitation/deposition, and a commercial catalyst were tested for activity and selectivity in the sunflower seed oil hydrogenation. An average turn‐over frequency of 2.57 s −1 was found for the catalysts, assuming inaccessibility of nickel in pores smaller than 2 nm and a constant nickel surface concentration poisoned by the reaction mixture. After studying the mass‐transfer steps, the effect of temperature (373‐453 K) and pressure (101‐608 kPa) on reaction rates in the kinetic regime was analyzed, and the corresponding apparent activation energies and reaction orders were obtained. Conclusions on the effect of temperature and pressure on the selectivity to the preferential hydrogenation of polyunsaturates ( S o ) and to the formation of trans ‐isomers ((S trans ) 0 ) in the kinetic regime were derived from the results. Finally, a similar analysis was carried out when diffusion limitations were known to be present.