NL7904849A - PROCESS FOR THE CATALYTIC HYDROGENIZING DESULPHASISING A RESIDUAL FRACTION OF A HYDROCARBON OIL. - Google Patents

Description

g 655A EAT

Applicants for Shell International Besearch Society B.7.,

Carel van Bylandtlaan 30 * 1s-Gravenhage

Short designation: "Process for the catalytic hydrodesulfurization of a residual fraction of a hydrocarbon oil"

The invention relates to a process for catalytically hydrogenating desulfurization of a residual fraction of a high metal content hydrocarbon oil.

When refining hydrocarbon oils, such as mineral oils and in particular petroleum, the light products are usually first removed by distillation under atmospheric pressure, then heavier fractions are separated by means of vacuum distillation, and the residual residue (the so-called short residue) is removed. deasphalted, whereby deasphalted vacuum residue 10 of a mineral oil (hereinafter also referred to as DAO) and asphalt are obtained. The heavier fractions (also referred to as vacuum distillate fractions) and the residual fractions, in particular DAO, can be used, inter alia, as a heavy fuel or as a feed material for catalytic cracking. In order to discharge as little sulfur compounds into the environment as possible when burning heavy fuel, it is necessary that the sulfur content of oils to be used as heavy fuel is as low as possible. If DAO and / or vacuum distillate fractions are used as feed for a catalytic cracking reaction, the metal content and the carbon deposit tendency of the feed to be used must be as low as possible to avoid rapid deactivation of the cracking catalyst.

In order to meet the requirements with regard to sulfur and metal content, in general both vacuum distillate fractions and residual fractions (including fractions that are residual in vacuum distillation) must be 790 4 8 49 i - 2 - τ r fractions. left behind or obtained from such a residue (eg short residue, DAQ, asphalt) are desulfurized, and at least a part of the metals, which are present in the residual fractions in a larger amount than in the vacuum distillate fractions, are removed. These metals are largely composed of nickel and vanadium, which can occur in not insignificant amounts in hydrocarbon oils, such as mineral oils.

In this application, a "high metal content" is understood to mean a metal content which is so high that the conventional catalysts for hydrogenation and desulfurization cannot withstand it.

The catalysts customary in catalytic desulfurization are not resistant to amounts of metal in the feed greater than + 20 parts by weight per million (ppm), because in the case of larger amounts of metal, inadmissible pressure drop across the catalyst occurs after a relatively short time. Therefore, with these catalysts, a residual fraction, eg, DAO sulfur, which has a metal content significantly higher than 20 ppm, cannot be economically viable. The metal content of the residual fraction can be so high that even after mixing all the desulfurization residual fraction with available vacuum distillate fractions (the latter fractions containing only small amounts of metal), the metal content of the mixture is still too high to desulfurize with conventional catalysts . It is, of course, possible to demetallize the residual fraction before desulfurization using an appropriate catalyst, but this requires the construction and operation of additional plants, which in many cases is unattractive.

The invention now provides a process in which products with desirable low sulfur and metal contents can nevertheless be obtained, using only catalytically hydrogenating desulfurization and without the lifespan of the desulfurization catalyst becoming unacceptably short.

The invention therefore relates to a process for 790 4 8 49 * - 3 - catalytic hydrodesulfurization of a residual fraction of a high metal content hydrocarbon oil, characterized in that a mixture of part of said residual fraction and at least at least a portion of a distillate fraction of a lower metal hydrocarbon oil in the presence of hydrogen is passed over a catalyst, and the remainder of the residual fraction is fed to the catalyst at one or more downstream locations.

As hydrocarbon oils can be mentioned mineral oils, such as slate oil, oil obtained from tar sands, and in particular petroleum.

As distillate fraction of a hydrocarbon oil, such as of a mineral oil, a vacuum distillate fraction is very suitably used, in particular a so-called "flashed distillate", which is a high-boiling oil obtained by vacuum distillation from petroleum. Generally, the boiling range of a flashed distillate is wholly or largely between 300 and 550 ° C, and the metal content is generally less than 5, especially less than 2 ppm.

As a residual fraction, a deasphalted vacuum residue (DAO) is very suitably used; the metal content thereof is generally considerably higher, and is, for example, of 20-60 ppm.

By mixing at least a part of the distillate fraction with a part of the residual fraction, a mixture can be obtained with much lower metal content than that of the residual fraction. Preferably, all flashed distillate made available in the vacuum distillation to prepare the respective residual fraction is used for this mixture and so much residual fraction is incorporated into the mixture that its metal content is so low that the mixture is without objection using a conventional desulfurization catalyst. can be hydrodesulfurized. The amounts of metal that the mixture can contain depend on the "metal sensitivity" (an indication of the amount of metal that may still be present in the feed 35 without causing problems) of 7904849 f * - - 4 - the specific desulfurization catalyst to be used. Preferably, a desulfurization catalyst is used which still satisfactorily fulfills its function when using feeds with up to 20 ppm metal.

The rest of the residual fraction is fed to the catalyst at one or more places downstream. Since this place (s) of the catalyst is also passed (or are passed) by the already partially or fully desulfurized and demetallized mixture which has been fed as feed at the beginning of the process, the residual fraction is mixed with it and has thus obtained mixture again has a metal content which is not harmful to the desulfurization catalyst. If the residual fraction has a very high metal content, and the metal content of the mixture obtained by adding the entire remainder of the residual fraction in one location downstream becomes too high, the remainder of the residual fraction is fed in different portions, each portion downstream of the previous one to the catalyst.

If desired, part of the distillate fraction can also be fed downstream at one or more locations.

Very suitably several catalyst beds are used in series, which are preferably arranged in several reactors.

As the catalyst known per se hydrodesulfurization catalysts can be used, such as catalysts consisting of a support on which one or more metals of groups VIB and VIII of the.

Periodic Table (and / or compounds of these metals such as sulfides or oxides thereof) are provided. Very suitable are catalysts containing cobalt and / or nickel together with molybdenum and / or tungsten. Silas, alumina and silica alumina are very suitable as carriers. Preference is given to catalysts containing 2-wt.% Nickel (calculated as oxide) and 8-wt.% Molybdenum calculated as oxide (percentages on support) on an alumina support with a surface area of 100-300 m / g and a pore volume of 0.3-0.7 ml / g, because such catalysts have a relatively low metal sensitivity, ie feeds 35 with relatively high metal content (up to + 20 ppm) can be used 790 4849 Ί, v - 5 - without unwanted consequences. The catalysts are "preferably sulfided before use.

The reaction conditions during hydrodesulfurization are the usual ones. Suitable are temperatures of 300-450 ° C, a total pressure of 45-150 bar, a hydrogen partial pressure of 30-120 bar, a spatial flow rate of 0.1-8.0 kg feed per kg catalyst per hour and an amount of hydrogen of 250-2000 nl per 1 feed. Very suitable are temperatures of 330 to 390 ° C, a total pressure of 70 to 95 bar, a hydrogen-10 partial pressure of 50 to 80 bar, a spatial flow rate of 0.2-0.4 kg feed per kg catalyst per hour, and an amount of hydrogen of 400-900 nl per 1 feed.

Desulfurized oil and hydrogen can be passed countercurrently over the catalyst, but it is preferred to pass the desulfurized oil and hydrogen in the same, preferably downward, direction over the catalyst, with the hydrogen wholly or partly in the oil can be solved.

The invention is elucidated with reference to the figure.

This figure is schematic, and auxiliary equipment such as pumps, valves, heat exchangers, cookers have been omitted for the essence of the invention.

Line 1 is fed residual fraction, part of which is mixed via line 2 with distillate fraction supplied via line 3. The mixture thus obtained is fed hydrogen via line 4, and the mixture of oil and hydrogen is fed via line 5 to reactor 6.

This reactor is filled with one or more fixed bed catalyst.

Under the conditions prevailing in this reactor, the oil mixture supplied is desulfurized, and then fed to reactor 8 via line 7. The rest of the residual fraction is fed to line 7 via line 9. In reactor 8, and downstream reactors 10 and 11 (each reactor contains one or more catalyst beds), the oil is further desulfurized, and the product is discharged through line 12.

The product obtained can be separated in known manner in gas and liquid, and the desulfurized liquid obtained can be separated by distillation into desulfurized residual fraction and desulfurized distillate fraction, if desired.

Example I

To 100 parts of flashed distillate with a sulfur content of 2.3% by weight and a metal content of 2 parts by weight per million (ppm), 36 parts of DAO with a sulfur content of 2.7% by weight and a metal content of 40 ppm are supplied. The resulting mixture has a metal content of 12.1 ppm and a sulfur content of 2.4 wt.%. The mixture is passed down a catalyst in the first reactor in the presence of hydrogen, reducing the metal content of the mixture to (1 ppm).

The catalyst consisted of an alumina support with a surface area of 246 m / g and a pore volume of 0.6 ml / g, on which 3> 7 wt.% Nickel oxide and 13 2 wt.% Molybdenum oxide (percentages based on support) was applied. The catalyst was sulphided before use.

Subsequently, 54 parts of the above-mentioned DA0 are again added to the 136 parts of demetallized stream, whereby the metal content of the mixture is again brought to 12.1 ppm. This mixture is fed to a second reactor with an identical desulfurization catalyst and desulfurized therein to a final sulfur content of 0.45% by weight. In order to maintain the sulfur content at this level, the reactor temperatures are gradually increased during the test. The metal content hereby drops to O ppm. The conditions are summarized in the table below.

Conditions 30 Flow rate, kg / l / hr 0.32

Hydrogen partial pressure, bar (outlet 2nd reactor) 70 "

Average reactor temperature ° C at the start of the test 330 °, „„ ° C at the end of the test 370 35 Hydrogen / feed ratio, nl / l ___ <____________650 7904849 X.

- 7 -

By adhering to the manner of operation described above, a catalyst life of 12,000 hours was achieved, after which rapid deactivation of the catalyst occurs.

Example II

5 In a comparative test, 190 parts DAO

(identical to that of example I, metal content 40 ppm, sulfur content 2.7 wt%) now without dilution with flashed distillate and without downstream DAO supply the same amount of sulfur as in under example I dv. Δia 1.95 according to S. A desulfurization catalyst identical to that described in Example 1 is used.

Conditions

Throughput rate, kg / l / hr 0.80 15 Barrel of dust particle voltage, bar (reactor outlet) - 70

Average reactor temperature, ° C at the start of the test 330 ° '' ° C at the end of the test 370

Hydrogen / Nutrient ratio nl / l 650 20 Due to the high metal content of the DAO, the catalyst service life now appears to be drastically limited to 1750 hours, so about 15% of the service life obtained in example I. After this, a rapid deactivation of the catalyst occurs. on.

Example III

In a comparative test, 100 parts of flashed distillate and 90 parts of DAO (both identical to those used in Example i) are mixed together and passed as such over a desulfurization catalyst (identical to that described in Example i). The sulfur and metal content of this mixture 30 were 2.5 wt% and 20 ppm, respectively. The same amount of sulfur as in Example 1 is removed (ΔSyn <product of 1.95% by weight).

790 4849 S '~' - 8 - _________ Conditions ___________________

Feed rate, -kg / l / hr 0.54

Hydrogen partial pressure, bar (reactor outlet) 70 5 Average reactor temperature, ° C at the start of the test 330 „„ „° C at the end of the test 370

Hydrogen / Nutrient ratio nl / l 650

The life of the desulfurization catalyst is now 59 hours, 49% of that achieved in Example 1. After this, rapid deactivation of the catalyst occurs.

Example 17

In a comparative test, 100 parts of flashed distillate and 90 parts of DAO (both identical to those used under Example 1) are mixed together and passed as such over a Ni / Mo desulfurization catalyst (identical to that of Example 1). . The S content and metal content of this mixture were 2.5 µm and 20 ppm m, respectively. The same spatial throughput rate as in Example 1 is maintained. The metal content of the product is reduced to 0 ppm. The amount of sulfur removed (ΔS feed product) is 2.3 wt.%.

Conditions

Throughput, kg / l / hr 0.32

Hydrogen partial pressure, bar 7 ° (reactor outlet) 25 Average reactor temperature, ° C at the start of the test 33 ° n n »° C tt .. end tf„ „370

Hydrogen / nutrition ratio, nl / l 65 °

The life of the desulfurization catalyst is now 4100 hours, 34% that of Example 1. After this, rapid deactivation of the catalyst occurs.

7904849

Claims (11)

A method for catalytically hydrodesulfurizing a residual fraction of a high metal content hydrocarbon oil, characterized in that a mixture of a part of said residual fraction and at least a part of a distillate fraction of a lower metal content hydrocarbon oil, is passed over a catalyst in the presence of hydrogen, and the remainder of the residual fraction is fed to the catalyst at one or more downstream locations. A method according to claim 1, characterized in that the hydrocarbon oil is a mineral oil. Process according to claims 1-2, characterized in that the residual fraction is a deasphalted vacuum residue of a mineral oil. 15 Process according to one or more of the preceding claims, characterized in that the distillate fraction of a hydrocarbon oil is a vacuum distillate fraction. Process according to claim 4i, characterized in that the vacuum distillate fraction is a flashed distillate. Process according to claim 5t, characterized in that all flashed distillate which is made available in the vacuum distillation to prepare the respective residual fraction is incorporated into the mixture with a part of the residual fraction. 7. Process according to one or more of the preceding claims, characterized in that the catalyst contains cobalt and / or nickel, together with molybdenum and / or tungsten (and / or compounds of these metals) on a support. 8. Process according to claim 7, characterized in that the catalyst contains 2-6 wt.% Nickel (calculated as ozyde) and 8-16 wt.% Molybdenum (calculated as oxide) on an alumina support with a surface area of 100 -300 m / g and a pore volume of 0.3-0.7 ml / g. 9. Process according to one or more of the preceding claims, characterized in that the oil to be desulphurised and the hydrogen are passed over the catalyst in the same direction in 790 4 8 49 - 10%. 10. Process according to one or more of the preceding claims, characterized in that the hydrodesulfurization is carried out at a temperature of 300-450 ° C, a total pressure of 45-150 har, a hydrogen partial pressure of 5 ° to 120 har, a spatial throughput rate. of 0.1-8.0 kg feed per kg catalyst per hour, and an amount of hydrogen of 250-2000 nl per 1 feed. 11. Process according to claim 10, characterized in that the hydrogenating desulfurization is carried out at a temperature of 330-390 ° C, a total pressure of 70 to. 95 har, a hydrogen partial voltage of 50 to 80 har, a spatial throughput of 0.2-0.4 hg feed per kg catalyst per hour, and an amount of hydrogen of 400-900 nl per 1 feed. 7904849