Precious metal and silica-alumina based catalyst and hydroisomer

Details Precious metal and silica-alumina based catalyst and hydroisomer Precious metal and silica-alumina based catalyst and hydroisomer

1996-04-03

1999-03-09

Caldarola, Glenn A.

Mineral oils: processes and products

Chemical conversion of hydrocarbons

Reforming

208216PP, 502332, 502333, 502334, 502235, 502238, 502258, 502261, 502263, C10G 3506, B01J 2356

Patent

active

058795391

DESCRIPTION:

BRIEF SUMMARY
SUMMARY OF THE INVENTION

The present invention concerns a catalyst used in hydroconversion processes for feeds with reduced metal contents.
The present invention also concerns a hydroconversion and hydroisomerization process for feeds with boiling points which are essentially above 350.degree. C. and with reduced metal contents.
The process is particularly advantageous for the hydroisomerization treatment of feeds (such as hydrocracking residues) to obtain very high added value products such as kerosine, gas oils and lubricating oils.
A number of catalysts can be used to carry out the hydroisomerization reaction. U.S. Pat. No. 4,,929,795, for example, describes the use of a catalyst composed of 0.6% by weight of platinum deposited on a halogenated alumina containing 7.2% by weight of fluorine to obtain lubricating oils from paraffins. We have developed a halogen-free catalyst which can be used in a simpler process since the catalyst just described requires continuous injection of the fluorinated compound into the catalytic unit.
U.S. Pat. No.4,428,819 describes a catalyst containing a zeolite which is used to carry out the isomerization of a mixture of paraffins from oil mixed with a lubricating oil obtained by catalytic deparaffination with a view to improving the cloud point. Finally, U.S. Pat. No. 4,547,283 describes a hydroisomerization catalyst for paraffins from oil containing at least one active metal from group 2A, 3A, 4A and/or 4B of the periodic classification of the elements on a support which is preferably silica.
We have developed a catalyst which is easier to use by avoiding the use of the zeolite or addition of supplemental elements during manufacture of the catalyst.
All the catalysts which are currently used for hydroconversion are bifunctional, combining an acidic function with a hydrogenating function. The acidic function is provided by supports with large surface areas (generally 150 to 800 m.sup.2 g.sup.-1) with surface acidity, such as halogenated aluminas (in particular chlorinated or fluorinated), phosphorous-containing aluminas, combinations of boron oxides and aluminium, amorphous silica-aluminas and silica-aluminas. The hydrogenating function is provided either by one or more metals from group VIII of the periodic classification of the elements, such as iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum, or by combination of at least one metal from group VI such as chromium, molybdenum and tungsten with at least one metal from group VIII.
The balance between the acidic and hydrogenating functions is a fundamental parameter which governs the activity and selectivity of the catalyst. A weak acidic function and a strong hydrogenating function produces catalysts which are less active and selective as regards isomerization while a strong acidic function and a weak hydrogenating function produces very active and selective catalysts as regards cracking. A third possibility is to use a strong acidic function and a strong hydrogenating function to obtain a very active but also very selective isomerization catalyst. It is thus possible, by judicious choice of each of the functions, to adjust the activity/selectivity balance of the catalyst.
Our research on a number of silica-aluminas has led to the discovery that, surprisingly, the use of a catalyst comprising a particular silica-alumina can produce catalysts which are very active but also very selective in certain reactions such as isomerization of feeds as defined below.
More precisely, the catalyst of the invention is essentially constituted by 0.05-10% by weight of at least one precious metal from group VIII deposited on an amorphous silica-alumina support which contains 5-70% by weight of silica and has a BET specific surface area of 100-500 m.sup.2 /g, the catalyst having: defined above reduced by 3 nm and the average diameter as defined above increased by 3 nm, of more than 40% of the total pore volume,
In more detail, these characteristics are:
Silica content: composed of silica SiO.sub.2 and alumina

REFERENCES:
patent: 5157187 (1992-10-01), Le et al.

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