Catalyst comprising a zeolite Y globally non-dealuminated...

Details Catalyst comprising a zeolite Y globally non-dealuminated... Catalyst comprising a zeolite Y globally non-dealuminated...

2001-10-01

2004-04-13

Griffin, Walter D. (Department: 1764)

Mineral oils: processes and products

Chemical conversion of hydrocarbons

Cracking

C208S111010, C208S111050, C208S111300, C208S058000

Reexamination Certificate

active

06719895

ABSTRACT:

The present invention relates to a catalyst for hydrocracking hydrocarbon-containing feeds, said catalyst comprising at least one metal selected from group VIB and group VIII (group 6 and groups 8, 9 and 10 in the new notation for the periodic table: Handbook of Chemistry and Physics, 76
th
edition, 1995-96), preferably molybdenum or tungsten, cobalt, nickel or iron, associated with a support comprising an amorphous or low crystallinity oxide type alumina and a non dealuminated Y zeolite with a lattice parameter of more than 2.438 nm. The alumina matrix of the catalyst comprises boron and/or silicon and optionally phosphorous, and optionally at least one element from group VIIA (group 17, the halogens), in particular fluorine, and optionally at least one group VIIB element.
The present invention also relates to processes for preparing said catalyst, and to its use for hydrocracking hydrocarbon-containing feeds such as petroleum cuts, or cuts from coal containing sulphur and nitrogen in the form of organic compounds, such feeds possibly containing metals and/or oxygen.
Conventional hydrocracking of petroleum feeds is a very important refining process which produces lighter fractions such as gasoline, jet fuel and light gas oil from surplus heavy feeds, which lighter fractions are needed by the refiner so that he can match production to demand. The importance of catalytic hydrocracking over catalytic cracking is that it can provide very good quality middle distillates, jet fuels and gas oils.
All catalysts used for hydrocracking are bifunctional, combining an acid function and a hydrogenating function. The acid function is supplied by large surface area supports (150 to 800 m
2
/g in general) with a superficial acidity, such as halogenated aluminas (in particular fluorinated or chlorinated), combinations of boron and aluminium oxides, amorphous silica-aluminas and zeolites. The hydrogenating function is supplied either by one or more metals from group VIII of the periodic table, such as iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium or platinum, or by a combination of at least one metal from group VIB of the periodic table such as chromium, molybdenum or tungsten, and at least one group VIII metal, preferably non noble.
The equilibrium between the two, acid and hydrogenating, functions is the fundamental parameter which governs the activity and selectivity of the catalyst. A weak acid function and a strong hydrogenating function produces low activity catalysts which generally operate at a high temperature (390° C. or above), and at a low supply space velocity (HSV, expressed as the volume of feed to be treated per unit volume of catalyst per hour, and is generally 2 or less), but have very good selectivity for middle distillates. In contrast a strong acid function and a weak hydrogenating function produces very active catalysts but selectivities for middle distillates are poor. Further, a weak acid function is less sensitive to deactivation, in particular by nitrogen-containing compounds, than a strong acid function. The problem is thus the proper selection of each of the functions to adjust the activity/selectivity balance of the catalyst.
Weakly acid supports are generally constituted by amorphous or low crystallinity oxides. Weakly acidic supports include amorphous silica-aluminas. Certain catalysts on the hydrocracking market are constituted by silica-alumina combined with a combination of sulphides of groups VIB and VIII metals. Such catalysts enable feeds containing large quantities of heteroatomic poisons, sulphur and nitrogen, to be treated. The selectivity of such catalysts for middle distillates is very good. The disadvantage of such catalytic systems based on an amorphous support is their low activity.
Supports with a high acidity generally contain a dealuminated zeolite, for example a dealuminated Y type zeolite or USY (Ultra Stable Y zeolite), combined with a binder, for example alumina. Certain catalysts on the hydrocracking market are constituted by a dealuminated Y zeolite and an alumina combined either with a group VIII metal or with a combination of sulphides of group VIB and VIII metals. Such catalysts are preferably used to treat feeds containing less than 0.01% by weight of heteroatomic poisons, sulphur and nitrogen. Such systems are very active and the products formed are of high quality. The disadvantage of such catalytic systems based on a zeolitic support is that their selectivity for middle distillates is a little poorer than catalysts based on an amorphous support, and a high sensitivity to nitrogen content. Such catalysts can only tolerate low amounts of nitrogen in the feed, in general less than 100 ppm by weight.
The Applicant has discovered that to obtain a hydrocracking catalyst with good activity and good stability for feeds with high nitrogen contents, it is advantageous to combine an alumina type acidic amorphous oxide matrix doped with at least one element selected from boron and silicon, and optionally phosphorous and optionally at least one group VIIA element, in particular fluorine, with a highly acidic globally dealuminated Y zeolite.
The term “globally non dealuminated zeolite” means a Y zeolite with a faujasite structure (“Zeolite Molecular Sieves: Structure, Chemistry and Uses”, D. W. BRECK, J. Wiley & Sons, 1973). The lattice parameter of this zeolite may have been reduced by extracting aluminium from the structure or framework during its preparation but the global SiO
2/
Al
2
O
3
ratio is not changed since the aluminium atoms have not been chemically extracted. The zeolite crystals thus contain aluminium extracted from the framework in the form of extra-framework aluminium. Such a globally non dealuminated zeolite thus has a silicon and aluminium composition, expressed as the global SiO
2
/Al
2
O
3
ratio, equivalent to the non dealuminated starting Y zeolite. This globally non dealuminated Y zeolite can be in its hydrogen form, i.e., at least partially exchanged with metal cations, for example using cations of alkaline-earth metals and/or cations of rare earth metals with atomic number 57 to 71 inclusive.
The catalyst of the present invention generally comprises at least one metal selected from the following groups in the following amounts, as a percentage by weight with respect to the total catalyst mass:
0.1% to 30% of at least one group VIII metal and/or 1-40% of at least one group VIB metal (% oxide);
1% to 99.7%, preferably 10% to 98%, more preferably 15% to 95%, of at least one amorphous or low crystallinity alumina matrix;
0.1% to 80%, or 0.1% to 60%, preferably 0.1% to 50%, of at least one globally non dealuminated Y zeolite with a lattice parameter of more than 2.438 nm, a global SiO
2
/Al
2
O
3
mole ratio of less than 8, and a framework SiO
2
/Al
2
O
3
mole ratio, calculated using the Fichtner-Schmittler correlation (Cryst. Res. Tech. 1984, 19, K1) of less than 21 and above the global SiO
2
/Al
2
O
3
ratio;
0.1% to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10%, of at least one promoter element selected from the group formed by boron and silicon (% oxide);
and optionally:
0 to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10%, of phosphorous (% oxide);
0 to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10% by weight, of at least one element selected from group VIIA, preferably fluorine;
0 to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10% by weight, of at least one element selected from group VIIB, preferably manganese or rhenium.
The catalysts obtained in the present invention are formed into grains of different shapes and dimensions. They are generally used in the form of cylindrical or polylobed extrudates such as bilobes, trilobes, or polylobes with a straight or twisted shape, but they can also be produced and used in the form of compressed powder, tablets, rings, beads or wheels. The specific surface area is measured by nitrogen adsorption using the BET method (Brunauer, Emmett, Teller, J. Am. Chem. Soc., vol. 60, 309-316 (1938)) and is more than 140 m
2
/g,

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