Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Silicon containing or process of making
Patent
1995-06-12
1997-04-01
Baxter, Janet C.
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Silicon containing or process of making
502250, 502240, 502252, 502329, B01J 2112
Patent
active
056165315
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a nickel/silica catalyst having a molar ratio Ni/SiO.sub.2 of 10 to 2.5 for hydrotreating unsaturated organic compounds, and to a method for the preparation of a nickel/silica catalyst having a molar ratio Ni/SiO.sub.2 of 10 to 2.5 in which method a water insoluble nickel compound is precipitated from an aqueous solution containing a soluble nickel compound and combined with the supporting material, the resulting product being collected by filtration, washed, dried, and optionally calcined and reduced (activated). Commercial products containing the catalyst may be obtained by dispersing the reduced catalyst in fat or by extrusion or pelletizing a mixture of a calcined, or alternatively a reduced and passivated, catalyst and a binder. The invention further relates to a method for hydrogenating animal and vegetable fats and oils.
Nickel/silica catalysts having a molar ratio Ni/SiO.sub.2 in the range of 10 to 2.5 for hydrotreating unsaturated organic compounds as such are known, for instance from the published European patent applications 0 145 094 and 0 167 201. The published patent applications disclose a method for the preparation of supported nickel catalysts, which catalysts optionally may comprise in addition to silica also alumina as a supporting material, in which method in a first step a water insoluble nickel compound is precipitated by combining an aqueous solution of a nickel compound with an aqueous solution of an alkaline precipitating agent, keeping the precipitate in suspension and adding in a following step an aqueous solution comprising a metal silicate e.g. sodium silicate and optionally a metal aluminate e.g. sodium aluminate to the suspension, optionally maturing the resulting precipitate in suspension, collecting the precipitate, drying the precipitate, washing the precipitate, optionally calcining the precipitate and subsequently reducing (activating) the precipitate.
Published European patent application 0 322 049 discloses that nickel/silica catalysts may contain an amount of a Group II metal in a molar ratio of X/Ni of 0.05 to 0.15. Group IIA metals, in particular magnesium and barium, are preferred. It is not disclosed in the patent application whether the presence of a Group II metal has a beneficial effect with regard to properties of the catalyst, such as activity and/or selectivity. From table I present in the European patent application it may however be deduced that the presence of magnesium results in an increase of the nickel surface area and, consequently, in an increase of the activity of the catalyst. It has been established in practice that magnesium contents resulting in a molar ratio Mg/Ni greater than 0.15 reduce the selectivity and the activity of these catalysts. With barium virtually only the pore volume of the catalyst seems to increase to some extent.
Although the methods disclosed in the patent applications referred to in the preceding paragraphs have certain advantages in comparison to other methods of preparation, nickel/silica catalysts may also be obtained by precipitating nickel and supporting material simultaneously from solution (coprecipitation method) or nickel may be precipitated on a supporting material present in suspension (impregnation method).
Surprisingly, it has now been found that zinc may decisively and effectively improve the quality of nickel/silica catalysts having a molar ratio Ni/SiO.sub.2 of 10 to 2.5, in particular as to their activity and/or selectivity in the hydrogenation of unsaturated animal and vegetable fats and oils. The improvement caused by the presence of zinc has also been found with nickel/silica catalysts which in addition contain magnesium as a promotor.
A nickel/silica catalyst according to the invention is characterized in therefore that the catalyst contains at least a small but effective amount of zinc to improve the activity and/or selectivity of the catalyst in the hydrogenation of unsaturated animal and vegetable fats and oils.
A catalyst according to a preferred embodiment of the invention
Feldhauser Brigitte
Koetsier Wicher T.
Lok Cornelis M.
Baxter Janet C.
Harding Amy M.
Unichema Chemie B.V.
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