Mineral oils: processes and products – Refining – Sulfur removal
Reexamination Certificate
1999-01-19
2001-02-13
Utech, Benjamin L. (Department: 1764)
Mineral oils: processes and products
Refining
Sulfur removal
C208S108000, C208S146000, C208S152000, C208S153000, C208S157000, C208S25100H
Reexamination Certificate
active
06187174
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to refining and converting heavy hydrocarbon fractions containing, inter alia, asphaltenes and sulphur-containing and metallic impurities. More particularly, it relates to a process for improving the activity of continuously added fresh catalyst in an ebullated bed hydroconversion process with an apparatus for in-line addition of fresh catalyst and extraction of used catalyst, for example the H-Oil process described in United States patents U.S. Pat. No. 4,521,295 or U.S. Pat. No. 4,495,060 or U.S. Pat. No. 4,457,831 or U.S. Pat. No. 4,354,852 or in the NPRA article, March 16-18, San Antonio, Tex., paper number AM 97-16.
SUMMARY OF THE INVENTION
The present invention relates to a method of conditioning and treating a catalyst before introducing it into a high temperature, high pressure reactor.
The process can be defined as a process for converting a heavy hydrocarbon fraction with a Conradson carbon of at least 10% by weight, and a metal content of at least 50 ppm, normally at least 100 ppm and usually at least 200 ppm by weight. The feeds which can be treated comprise at least 0.5% by weight of sulphur, normally more than 1% by weight of sulphur, frequently more than 2% by weight of sulphur and usually up to 4% or even up to 10% by weight of sulphur, and at least 1% by weight of C
7
asphaltenes. The asphaltenes content (resulting, for example, from solvent extraction of C
7
) in feeds treated in the context of the present invention is normally over 2%, usually over 5% by weight, and can equal or even exceed 24% by weight.
The hydrocarbon feed is treat ed in a hydroconversion section in the presence of hydrogen, the section comprising at least one three-phase reactor containing at least one ebullated bed of hydroconversion catalyst, operating in riser mode for liquid and for gas, said reactor comprising at least one means for extracting catalyst from said reactor and at least one means for adding fresh catalyst to said reactor, under conditions which produce a liquid effluent with a reduced Conradson number, and reduced metals and sulphur contents.
The conditions for treating the feed in the presence of hydrogen are normally as follows. At least one conventional granular hydroconversion catalyst is used in the hydroconversion zone. That catalyst can be a catalyst comprising group VIII metals, for example nickel and/or cobalt, usually in combination with at least one group VIB metal, for example molybdenum. A catalyst comprising 0.5% to 10% by weight of nickel or cobalt, preferably 1% to 5% by weight of nickel or cobalt (expressed as the nickel or cobalt oxide) and 1% to 30% by weight of molybdenum, preferably 5% to 20% by weight of molybdenum (expressed as molybdenum oxide MoO
3
) can be used on a support, for example a support containing a mineral oxide, preferably selected from the group formed by alumina and silica. The catalyst is usually in the form of extrudates or beads.
The absolute pressure is normally 5 to 35 MPa, usually 10 to 25 MPa, and the temperature is about 300° C. to about 500° C., normally about 350° C. to about 450° C. The hourly space velocity (HSV) of the liquid and the partial pressure of hydrogen are important factors which are selected as a function of the characteristics of the feed to be treated and the desired conversion. The HSV of the liquid is usually about 0.1 to about 5 h
−1
, preferably about 0.15 to about 2 h
−1
, and the quantity of hydrogen mixed with the feed is about 50 to 5000 Nm
3
/m
3
.
Used catalyst is partially replaced by fresh catalyst by gradually (periodically or continuously) extracting used catalyst from the bottom of the reactor and gradually(periodically or continuously) adding fresh or new catalyst to the top of the reactor, for example at regular time intervals, for example daily. The rate of replacing used catalyst with fresh catalyst can, for example, be about 0.05 kilograms to about 10 kilograms per cubic meter of feed. Such gradual extraction and replacement are carried out using apparatus enabling this hydroconversion step to be operated continuously. The reactor normally includes a re-circulation pump which maintains the catalyst in an ebullated bed by continuously recycling at least a portion of the liquid extracted from the head of the reactor and re-injecting it at the bottom of the reactor.
At least one catalyst can be used, ensuring both demetallisation and desulphurisation, under conditions which produce a liquid feed with a reduced metal content, reduced Conradson carbon and reduced sulphur content and which can produce a high rate of conversion of light products, i.e., in particular of gasoline fuel and gas oil fractions.
In its most general form, the present invention provides a process for converting a heavy hydrocarbon fraction comprising a section for hydroconversion carried out in the presence of hydrogen, the section comprising at least one three-phase reactor containing at least one ebullated bed of hydroconversion catalyst operating in riser mode for liquid and for gas, said reactor comprising at least one means for extracting used catalyst from said reactor and at least one means for adding fresh catalyst to said reactor, under conditions which produce a liquid feed with a reduced Conradson carbon, a reduced metal content, and a reduced sulphur content, characterized in that the catalyst or catalysts are pre-conditioned before being injected into the reactor or reactors, said pre-conditioning producing a catalyst which is at least partially sulphurised.
The heavy hydrocarbon fraction which is treated in the present invention is normally an atmospheric residue or a vacuum residue or a mixture of the two residues with a Conradson carbon of at least 10% by weight, a metal content of at least 50 ppm by weight, an asphaltene content of at least 1% by weight and a sulphur content of at least 0.5% by weight. This heavy hydrocarbon fraction can also be a vacuum distillate or a deasphalted oil with an initial boiling point of at least 300° C. and a sulphur content of at least 0.5% by weight, or a heavy coking distillate, or a heavy fluidised bed catalytic cracking distillate, or an aromatic extract, or a mixture of at least two of these products.
More particularly, the present invention concerns pre-treatment of fresh catalyst added to the ebullated bed reactor, in accordance with the steps described below.
The catalyst is transported from its storage point to a receptacle for nitrogen inerting. The catalyst is weighed then transferred under gravity to a further receptacle where the conditioning operations are carried out. This latter receptacle is pressurised under hydrogen and a petroleum cut which may have been heated can be injected, for example a heavy vacuum distillate (VGO).
Firstly, then, the catalyst is wetted using this petroleum cut, for example a VGO, at a temperature of 320° C., for example.
The receptacle is then pressurised under hydrogen to the pressure of the reactor, for example 20 MPa. The petroleum cut is then circulated and its temperature is adjusted to the operating conditions for forming the catalyst. In a conventional unit, the catalyst is injected in this form. The present invention consists of pre-conditioning the catalyst before introducing the catalyst into the reactor. This pre-conditioning can be offsite deposition of sulphur-containing compounds onto the catalyst followed by sulphurisation proper (passage from the oxide to the sulphide) near the hydroconversion reactor, or complete offsite sulphurisation of the catalyst (passage from the oxide state to the sulphide state).
A description of a number of pre-conditioning types will now be given:
a) The fresh catalyst can be mixed in a receptacle near the hydroconversion reactor (i.e., offsite, or ex situ) with a petroleum cut, for example a vacuum distillate (VGO) and with a sulphur-containing compound, said sulphur-containing compound normally being a sulphurisation additive with a high sulphur content which can, for example, be dimethyldisulphide (DMDS: 66%
Harle Virginie
Kasztelan Slavik
Kressmann Stephane
Morel Frederic
Institut Francais du Pe'trole
Millen White Zelano & Branigan P.C.
Preisch Nadine
Utech Benjamin L.
LandOfFree
Process for converting heavy petroleum fractions in an... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for converting heavy petroleum fractions in an..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for converting heavy petroleum fractions in an... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2559648