JPH0135036B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for catalytic hydrodesulfurization of hydrocarbon oil residues with high metal content.

When refining mineral oils and especially hydrocarbon oils such as petroleum, the light products are usually first removed by distillation at atmospheric pressure, then the heavy fractions are separated by vacuum distillation, and the remaining residual oil (soil) is removed. deasphalted vacuum residue of a mineral oil
oil (hereinafter referred to as DAO) and asphalt are obtained. Heavy fractions obtained from vacuum distillation (also known as vacuum distillate fractions) and residual fractions, especially
DAO can be used inter alia as a heavy fuel or as a feedstock for catalytic pyrolysis. In order to emit the minimum possible amount of sulfur compounds into the atmosphere during the combustion of heavy fuels, it is necessary to make the sulfur content of the oil used as heavy fuel as low as possible. DAO and/or vacuum distillate
When using distillate fractions as feedstock for catalytic pyrolysis reactions, the metal content and coke deposition tendency of the feedstock used must be as low as possible in order to prevent rapid deactivation of the pyrolysis catalyst.

In order to meet the conditions set with respect to sulfur and metal content, vacuum distillation fractions and residual oil fractions (fractions remaining as residue in vacuum distillation or fractions obtained from such residues, e.g. ) generally have to be desulfurized and at least a portion of the metals present in higher amounts in the resid than in the vacuum distillation fraction must be removed. These metals consist mostly of nickel and vanadine, which can be present in significant amounts in hydrocarbon oils such as mineral oil.

As used herein, "high metal content" means such a high metal content that conventional hydrodesulfurization catalysts cannot tolerate.

Catalysts typically used for catalytic desulfurization weigh approximately 20 wt.
Metal levels in the feedstock higher than ppm cannot be tolerated. For higher metal contents,
This is because after a relatively short time an unacceptable pressure drop occurs across the catalyst. For this reason,
Residual oils with metal contents substantially higher than 20 ppm, such as DAO, cannot be desulfurized by these catalysts in an economically reasonable manner. The metal content of the resid can be very high, and even after mixing the entire resid to be desulphurized with the available vacuum distillation fraction, which contains only small amounts of metals, the mixture is The metal content may be too high for conventional catalytic desulfurization. It is of course possible to demetalize the residual oil fraction with suitable catalysts before desulfurization, but this often requires the construction and operation of an extra plant, which is not attractive.

The present invention provides a process which applies only catalytic hydrodesulfurization and which makes it possible to obtain products with the desired low sulfur and low metal contents without unacceptably shortening the life of the desulfurization catalyst. provide.

Therefore, the present invention provides a method for catalytic hydrodesulfurization of the residual oil of a hydrocarbon oil having a metal content higher than 20 ppmw, in which a part of the residual oil is converted into a distillate fraction of a hydrocarbon oil having a metal content lower than 20 ppmw. This mixture is passed over a catalyst in the presence of hydrogen, and the remainder of the residual oil is fed to the catalyst at one or more downstream points.

Hydrocarbon oils may include shale oil, oil recovered from tar sands, and mineral oils, especially petroleum.

As a distillate fraction of hydrocarbon oil such as mineral oil,
Vacuum distillate fractions, especially “flashed distillate oils”
It is very suitable to use high-boiling oils obtained from petroleum by vacuum flash distillation.The boiling range of flash distillate oils is generally
All or most of the temperature is between 300 and 550°C and the metal content is generally less than 5 ppm, especially less than 2 ppm.

Deasphalted vacuum resid (DAO) is very suitably used as resid; its metal content is generally quite high, for example 20-60 ppm.

By mixing at least a portion of the distillate fraction with a portion of the resid fraction, a mixture is obtained that has a significantly lower metal content than the resid fraction. The mixture includes:
It is preferable to use all of the flash distillate obtained in the vacuum distillation for the production of the residual oil, such that the metal content of the mixture is such that it can be hydrodesulphurized without hindrance by conventional desulphurization catalysts. A low amount of residual oil is incorporated into the mixture. The amount of metal that the mixture may contain will of course depend on the "metal sensitivity" of the particular desulfurization catalyst being used (a measure of the amount of metal that can still be present in the feed without causing problems). . It is preferred to use a desulfurization catalyst that can accommodate feedstocks containing up to 20 ppm of metals and still be operationally satisfactory.

The remainder of the resid fraction is provided at one or more points downstream of the catalyst. The point of the catalyst is also passed through the mixture which was fed as feed at the beginning of the process and which has already been completely or partially deflowed and demetallized, so that the residual oil is mixed with it and thus The resulting mixture also has a metal content that is not harmful to the desulfurization catalyst. If the resid has a very high metal content and the metal content of the mixture obtained during the addition of the entire resid at one downstream point becomes too high, then is supplied to the catalyst in that part,
Each part is further downstream than the previous one.

If desired, a portion of the distillate fraction can also be fed at one or more downstream points. Very suitably, several catalyst beds are used in series. They are preferably arranged in several reactors.

Catalysts known per se, such as catalysts comprising one or more metals of groups B and groups of the periodic table (and/or compounds of said metals, such as their sulfides or oxides) deposited on a support. Hydrodesulfurization catalysts can be used. Cobalt and/or molybdenum and/or tungsten
Or catalysts containing nickel are very suitable.
Silica, alumina and silica-alumina are very suitable as supports. 2-6% by weight of nickel (calculated as oxide) and 8-16% by weight of nickel (calculated as oxide) on an alumina support with a surface area of 100-300 m ² /g and a pore volume of 0.3-0.7 ml/g.
Molybdenum in weight % (percentage based on carrier)
A catalyst containing is preferred. This is because this type of catalyst has a relatively low metal sensitivity, such that feedstocks with relatively high metal contents (up to about 20 ppm) can be used without undesirable effects. Preferably, the catalyst is sulfided before use.

The reaction conditions for hydrodesulfurization are conventional. 300
-450℃ temperature, 45-150 bar total pressure, 30-120
Hydrogen partial pressure in bar, feedstock space velocity of 0.1-8.0Kg per hour per kg of catalyst and per liter of feedstock
A hydrogen amount of 250-2000n is suitable. 330−390
℃ temperature, a total pressure of 70-95 bar, a hydrogen partial pressure of 50-80, a feedstock space velocity of 0.2-0.4 Kg per hour per kg of catalyst, and a hydrogen amount of 400-900 n per liter of feedstock are very suitable. .

Although it is also possible to pass the oil to be desulfurized and the hydrogen over the catalyst countercurrently, it is preferable to pass the oil to be desulfurized and the hydrogen over the catalyst in the same, preferably downward direction, in which case the hydrogen is completely or Can be partially dissolved in oil.

Next, the present invention will be explained with reference to the drawings. The figure is a schematic diagram and auxiliary components not essential to the essence of the invention, such as pumps, valves, heat exchangers and furnaces, have been omitted.

Residue is fed through line 1, a portion of which is mixed through line 2 with the distillate fraction fed from line 3. Hydrogen is fed to the mixture thus obtained through line 4, and this mixture of oil and hydrogen is fed through line 5 to reactor 6. The reactor is packed with one or more fixed catalyst beds. Under normal conditions in the reactor, the oil mixture introduced is desulfurized and then fed through line 7 to reactor 8.
The remainder of the residual oil is supplied to line 7 through line 9. In reactor 8 and subsequently connected reactors 10 and 11 (each containing one or more catalyst beds), the oil is further desulfurized and the product is discharged through line 12.

The product obtained can be separated into gas and liquid in known manner and, if desired, the desulfurized liquid obtained is separated by distillation into a desulfurized bottom oil fraction and a desulfurized distillate fraction. be able to.

Example: 100 parts of a sulfur distillate having a sulfur content of 2.3% by weight and a metal content of 2 ppm by weight has a sulfur content of 2.7% by weight and a metal content of 40 ppm by weight.
Add 36 parts DAO. The resulting mixture is
It has a metal content of 12.1ppm and a sulfur content of 2.4% by weight. The mixture is passed downwardly over the catalyst in the first reactor in the presence of hydrogen. At this stage the metal content of the mixture is reduced to <1 ppm.

The catalyst consisted of 3.7% by weight nickel oxide and 13.2% by weight molybdenum oxide (percentage based on support) deposited on an alumina support with a surface area of 246 m ² /g and a pore volume of 0.6 mm/g. It is. The catalyst is sulphurized before use.

A further 54 parts of the above DAO are then added to the 136 parts of the demetalized stream, so that the metal content of the mixture is again 12.1 ppm. This mixture is desulfurized by passing it through a second reactor with the same desulfurization catalyst to a final sulfur content of 0.45% by weight. The reactor temperature is gradually increased during the test to maintain the sulfur content at that level. At the same time the metal content is reduced to <1 ppm. The conditions are summarized below.

Conditions Space velocity 0.32Kg//h Hydrogen partial pressure (second reactor outlet) 70 bar Average reactor temperature at the start of the test 330℃ Average reactor temperature at the end of the test 370℃ Hydrogen/feedstock ratio 650n/ The above operating method By maintaining this, a catalyst life of 12000 hours is obtained; after which rapid deactivation of the catalyst occurs.

Example In a comparative test, a ΔS feedstock equal to the same amount of sulfur as in the example, i.e. 1.95% by weight S -
The product was prepared from 190 parts of DAO (same as that in the example; metal content 40 ppm, sulfur content 2.7% by weight), this time without dilution with flash distillate, and DAO
removed without downstream addition of. The same desulfurization catalyst as described in the example is used.

Conditions Space velocity 0.80Kg//h Hydrogen partial pressure (reactor outlet) 70 bar Average reactor temperature at start of test 330℃ Average reactor temperature at end of test 370℃ Hydrogen/feed ratio 650n/ High metal content of DAO Therefore, the catalyst life is now 1750 hours, or about 15% of the life obtained in the example.
drastically decreased. Rapid deactivation of the catalyst then occurs.

Example In a comparative test, 100 parts of flash distillate and 90 parts of DAO (both the same as used in the example) were thoroughly mixed and applied in neat form over a desulfurization catalyst (same as that described in the example). Pass. The sulfur content and metal content of this mixture are 2.5% by weight and 20 ppm, respectively. Remove the same amount of sulfur as in the example (ΔS feed - 1.95% by weight product).

Conditions Space velocity 0.54Kg//h Hydrogen partial pressure (reactor outlet) 70 bar Average reactor temperature at the start of the test 330℃ Average reactor temperature at the end of the test 370℃ Hydrogen/feedstock ratio 650n/ The life of the desulfurization catalyst is now over is 5900 hours, or 49% of that obtained in the example. Rapid deactivation of the catalyst then occurs.

Example In a comparative test, 100 parts of flash distillate and 90 parts of DAO (both the same as used in the example) were mixed thoroughly and the Ni/Mo
Pass over a desulfurization catalyst (same as that in the example). The S-content and metal content of this mixture are 2.5% by weight and 20 ppm, respectively.

Using the same space velocity as in the example. The metal content of the product is reduced to <1 ppm. The amount of sulfur removed (ΔS feed-product) is 2.3% by weight.

Conditions Space velocity 0.32Kg//h Hydrogen partial pressure (reactor outlet) 70 bar Average reactor temperature at the start of the test 330℃ Average reactor temperature at the end of the test 370℃ Hydrogen/feedstock ratio 650n/ Desulfurization catalyst life is 4100 time, 34% of that in the example
It is. Rapid deactivation of the catalyst then occurs.

[Brief explanation of drawings]

The figure is a schematic diagram of one embodiment of the method of the invention. 1, 9... Residual oil supply line, 3... Distillate fraction supply line, 4... Hydrogen supply line, 5... Oil-
Hydrogen-mixture supply lines, 6, 8, 10, 11...
...Reactor.

Claims (1)

[Claims] 1. In a catalytic hydrodesulfurization method for a residual oil of a hydrocarbon oil having a metal content higher than 20 ppmw, a part of the residual oil is converted into a distillate fraction of a hydrocarbon oil having a metal content lower than 20 ppmw. mixed with at least a portion of
A process characterized in that this mixture is passed over a catalyst in the presence of hydrogen and the remainder of the resid is fed to the catalyst at one or more downstream points. 2. The method according to claim 1, wherein the hydrocarbon oil is mineral oil. 3. The method according to claim 1 or 2, wherein the residual oil is a deasphalted vacuum residual of mineral oil. 4. The method according to any one of claims 1 to 3, wherein the distillate fraction of the hydrocarbon oil is a vacuum distillation fraction. 5. The method according to claim 4, wherein the vacuum distillation fraction is a flash distillate. 6. Process according to claim 5, characterized in that all the flash distillate obtained in the vacuum distillation for the production of the residual oil is incorporated into a mixture with a part of the residual oil. 7. The method according to any one of claims 1 to 6, characterized in that the catalyst contains cobalt and/or nickel as well as molybdenum and/or tungsten (and/or a compound of these metals) on a carrier. . 8 The catalyst has a surface area of 100-300 m ² /g and a surface area of 0.3-0.7
2- on an alumina support with a pore volume of ml/g.
6% by weight of nickel (calculated as oxide) and 8-16% by weight of molybdenum (calculated as oxide)
8. A method according to claim 7, characterized in that the method comprises: 9. Claim 1, characterized in that the oil to be desulfurized and the hydrogen are passed over the catalyst in the same direction.
The method according to any one of items 1 to 8. 10 Temperature of 300-450°C, total pressure of 45-150 bar,
Hydrogen partial pressure of 30−120 bar, 0.1− per kg of catalyst per hour
10. A process according to claim 1, characterized in that the hydrodesulfurization is carried out at a feed space velocity of 8.0 Kg and a hydrogen content of 250-2000 n per liter of feed. 11 Temperature of 330-390°C, total pressure of 70-95 bar,
Hydrogen partial pressure of 50−80 bar, 0.2− per kg of catalyst per hour
11. Process according to claim 10, characterized in that the hydrodesulfurization is carried out at a feed space velocity of 0.4 Kg and a hydrogen content of 400-900 n per liter of feed.