Irregularly shaped non-spherical supported catalyst, and a process for hydroconverting heavy oil fractions

Abstract

The present invention concerns a catalyst for hydrotreating and / or hydroconverting heavy metal-containing hydrocarbon feeds, said catalyst comprising a support in the form of mainly irregular and non-spherical alumina-based agglomerates the specific shape of which results from a crushing step, and containing at least one catalytic metal or a compound of a catalytic metal from group VIB and / or group VIII (groups 8, 9 and 10 of the new periodic table notation), optionally at least one doping element selected from the group constituted by phosphorus, boron and silicon (or silica which does not form part of that which may be contained in the selected support) and halogens, said catalyst essentially being constituted by a plurality of juxtaposed agglomerates each formed by a plurality of acicular platelets, the platelets of each agglomerate generally being oriented radially with respect to each other and with respect to the centre of the agglomerate. The specific shape of the catalyst improves its performance when using it for hydroconverting / hydrotreating heavy metal-containing hydrocarbon feeds.The invention also concerns the use of said catalyst alone or as a mixture in a fixed bed or ebullated bed reactor.

Description

FIELD OF THE INVENTION[0001]The present invention concerns a catalyst for hydrotreating and / or hydroconverting heavy metal-containing hydrocarbon feeds, said catalyst comprising a support in the form of mainly irregular and non-spherical alumina-based agglomerates the specific shape of which results from a crushing step, and comprising at least one catalytic metal or a compound of a catalytic metal from group VIB (group 6 in the new periodic table notation) and / or group VIII (groups 8, 9 and 10 of the new periodic table notation), optionally at least one doping element selected from the group constituted by phosphorus, boron and silicon (or silica which does not form part of that which may be contained in the selected support) and halogens, said catalyst essentially being constituted by a plurality of juxtaposed agglomerates each formed by a plurality of acicular platelets, the platelets of each agglomerate generally being oriented radially with respect to each other and with respec...

AI Technical Summary

Benefits of technology

[0028]The invention concerns a catalyst which can be used in fixed or ebullated bed hydrorefining (hydrotreatment) and / or hydroconversion of heavy metal-containing hydrocarbon feeds having both an improved activity, a high retention power, a high stability of performance and a high strength.

[0041]Without wishing to be bound by any particular theory, it appears that the improved properties of the catalyst of the present invention are due to improved diffusion of species into the interior of the catalyst grain and by association, the small size of the grains or fragments, their specific form resulting in a higher external surface area / grain volume ratio and to a thorny chestnut husk or sea-urchins porosity.

[0043]For an equal size, the specific shape of the grains or fragments, irregular and non-spherical, thus encourages intragranular diffusion phenomena. The hydrodemetallization (HDM) and hydroconversion functions of asphaltenes which are insoluble in n-heptane (HDAC7) are increased.

Problems solved by technology

That phenomenon may thus cause premature and major deactivation of the catalyst.

Pore obstruction goes hand in hand with a gradual reduction in their diameter, which increasingly limits diffusion of molecules and accentuates the concentration gradient and thus the heterogeneity of the deposit from the periphery to the interior of the porous particles, to the point that total obstruction of the pores mouth to the exterior occurs very rapidly: access to the almost intact internal porosity of the particles is thus impossible for the reagents and the catalyst is prematurely deactivated.

Catalysts with a bimodal porosity profile are highly active, but have a poorer retention capacity than catalysts with a polymodal porosity profile.

These catalysts, however, suffer from the disadvantage of being less active as regards initial activity than bimodal catalysts for HDM (hydrodemetallization), HDAC7 (hydroconverting asphaltenes which are insoluble in n-heptane), HDCCR (hydroconverting carbonaceous residues quantified by Conradson carbon analysis).

In processes for ebullated bed hydroconversion processing hydrocarbon feeds with high metal contents (Ni+V of more than 250 ppm, for example), the poorer initial performances of that catalyst with a thorny chestnut husk pore structure or sea-urchins pore structure requires a daily fairly large quantity of fresh makeup catalyst.

Similarly, in fixed bed processes for hydrorefining residues, the catalyst with a thorny chestnut husk or sea-urchins pore structure has a poorer performance (compared with bimodal catalysts) as regards the initial performance in the HDAC7, HDM, HDCCR functions, although they have a high retaining power which is necessary to process hydrocarbon feeds with a high metals content (Ni+V of more than 40 ppm, for example).

Thus, using that type of catalyst penalizes the performance of downstream HDS catalysts, which are thus poorly protected from asphaltenes, from Ni+V deposition and from coke deposition.