DE2136796A1 - Process for the selective hydrogenation of petroleum fractions that boil in the gasoline sector - Google Patents

Description

The present invention relates to a process for the selective hydrogenation of petroleum fractions from aromatic hydrocarbons, Diolefins and olefins, as well as sulfur compounds, which of at least three consecutive catalytic steps.

There are numerous processes for the selective hydrogenation of petroleum fractions, in addition to one more or less important aromatic fraction still contain diolefins, olefins and sulfur compounds. The aim of these procedures is elimination of the undesired compounds by hydrogenation of the diolefins and olefins and by hydrodesulfurization, so that one Finally, the aromatic compounds of the batch lightly

can detach.

BATH ORIGINAL

The catalytic one-step process where practical

109887/1702

hydrogenation and desulfurization are carried out at the same time, were quickly abandoned as the temperature required to desulfurize the batch easily leads to polymerization of the unstable ones Connections leads. The resins formed by this polymerization impair the convenience of the process.

Multi-stage catalytic ^ processes (e.g. two or three stages), in which the hydrogenation and the desulfurization of the batch are carried out in sequence are also known. So far however, the proposed methods have disadvantages. The olefins present in the batch are hydrogenated by means of a classic P hydrogenation catalyst, it is difficult to avoid hydrogenation of some of the aromatics in the batch. One leads the process with the aim of upgrading the aromatics through, this hydrogenation leads to losses of over 10% of the End product. One uses the classic hydrogenation catalysts in the first part of the process when the unstable compounds (like the diolefins) are not yet fully hydrogenated, so it is difficult to form polymers in the gas phase To avoid compounds that are deposited on the catalyst and lead to a rapid deactivation of the same.

The present invention relates to a process for k selective hydrogenation in at least three stages, one being in each stage uses a catalyst whose components (active metal and support) are selected in each case so that one avoids the above disadvantages.

The present invention relates to a process for the selective hydrogenation of petroleum fractions in the gasoline sector boil and contain aromatic hydrocarbons, diolefins, olefins and sulfur compounds, characterized that he

1.) in a first reaction zone said batch in liquid form Phase with hydrogen in the presence of a hydrogenation catalyst which contains a metal of Group VIII,

10 9 8 8 7/1702 BAD

2.) in a second reaction zone, the products obtained are treated in the gas phase with hydrogen in the presence of a catalyst with a specific surface area of 20 to 90 m / g, which contains at least one metal from the group molybdenum and tungsten, which are deposited on a support, 3 .) In a third reaction zone, the products obtained are treated in the gas phase with hydrogen in the presence of a catalyst with a specific surface area of 120 to 500 m / g, which contains at least one metal from the group molybdenum and tungsten, which are deposited on a support.

Under a petroleum fraction boiling in the range of gasolines, is meant a fraction boiling from at least 80 wt .-% i 30-220 ⁰ C. In such a process it is always interesting to treat a batch rich in aromatics; the process can be applied, for example, to those gasolines obtained by cracking (thermal, catalytic or steam cracking) of petroleum or gas oil or by coking the distillates.

The following are the reaction conditions for the inventive Procedure described in more detail.

The first reaction stage is carried out in the liquid phase, ie at least 50% by weight of the initial charge is always liquid at the exit of the first reaction zone, while the remaining fraction (if present) has been evaporated in the heating zone. The evaporation is based on the fact that the hydrogenation reaction is strongly exothermic. The internal temperature of the reaction zone is between 50 and 200 C; it should preferably not rise above 200 ° C. even at the exit of the zone if one wishes to avoid excessive polymerization. The liquid feed v; ith preferably at a temperature of 50 to 120 ⁰ C in the reaction zone introduced. The pressure must be high enough to keep the batch at least largely liquid; it is generally between 5 "and 60 kg / cm _f

ο preferably between 20 and 4-5 kg / cm.

BATH ORIGINAL 109887/1702

In this phase, the liquid batch is treated with a hydrogenation catalyst brought into contact, which contains a metal from group VIII of the periodic table, e.g. nickel, cobalt, Palladium or platinum. Nickel is the preferred metal] .. The metals used are preferably used in metal form; they can be deposited on supports and used in solid or liquid bed. You can do it too use as a suspension, e.g. Raney-Hickel or -obalt. at a preferred embodiment of the invention is used a supported catalyst and a fixed bed. The catalyst support consists of the usual support materials, e.g. aluminum oxide, Silicon oxide or mixtures thereof, magnesium oxide, clay,

W zeolite, etc. It is preferable to choose those carriers whose surface is slightly acidic (aluminum oxide or silicon oxide). The natural acidic surface of the support can also be neutralized by adding alkali or alkaline earth oxides. The supported catalysts usually contain 5 to 50% by weight of the active metal. The spatial velocity (VVH), ie the amount of the introduced charge per liter of catalyst and per hour can vary, for example, between 0.5 and 5, depending on the activity of the catalyst and depending on the content of unsaturated compounds in the charge. The amount of hydrogen introduced into the reaction zone can be varied so that the molar ratio hydrogen /

k hydrocarbons between about 0.1 to 1 is.

There is a substantial one at the exit of the first reaction zone Quantity of the batch still in the liquid state; this part is evaporated in the usual way, avoiding the formation of resin; E.g. only 90 to 99% of the liquid is evaporated.

Now, the gaseous batch enters the second reaction zone at a temperature of preferably ⁰ to 300 2 John C. The charge and the hydrogen are then brought into contact with a carrier catalyst. This catalyst contains a metal (molybdenum or tungsten), which alone or in a mixture with one or more metals of group VIII (e.g. cobalt or

109887/1702 ORIGINAL BATHROOM

*? 1 * 3 C * 7 Q C

Nickel "or their mixtures) can be used. The active elements of the catalyst are deposited on a support, which must have a particularly small surface: this surface is between, for example, 20 and 90 m / g. Suitable supports may be mentioned : Aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, etc. It is preferable to use practically neutral supports, ie those with a weak acidity of the surface (what is meant by a weak acidity of the support is indicated below). The temperature at the beginning of the reaction zone is between 230 and 360 ^° G; in order to avoid too great a temperature increase (because of the exothermic hydrogenation reaction), it is possible to introduce a fraction of the charge that originates from the first stage or in the The pressure inside the zone fluctuates between 25 and 60 kg / cm. The amount of hydrogen introduced is preferably so large oss that the molar ratio hydrogen / olefins is between 5 and Iß and that the partial pressure of the hydrogen at the level of the catalytic bed is 8 to 30 kg / cm. The rate at which the batch is introduced (VVH) is preferably between 4x and 20, the volume of the batch being measured in liquid form.

The second stage catalyst contains either a metal of the group molybdenum and tungsten or a mixture of these two metals with one or more metals of group VIII a preferred embodiment is chosen as the catalyst the pairs molybdenum-cobalt, molybdenum-nickel, tungsten-cobalt, Tungsten-nickel. The above catalysts can also be used in oxidized form; it is preferred to use them but in sulfurized form. If you have a good sulfuration wants to maintain the catalyst, it is preferably carried out in the presence of such an amount of hydrogen sulfide that dos volume ratio hydrogen sulfide / hydrogen between 200 and 4-000 ppm. For this purpose one can use the gas genius the third stage (where the desulfurization of the batch is terminated) · existing hydrogen sulfide in the circuit

• BATH 10 9887/1702

2736796

turn around.

If the catalyst consists only of molybdenum or V / o irr am, the proportion of .active elements is preferably 6 to 4-0 % By weight of the metal (expressed as oxide).

If the catalyst contains at least two metals, the is Amount preferably 4 to 25% by weight of molybdenum or tungsten (as Oxide) and 2 to 15% by weight of Group VIII metal (as Oxide).

fc The gas flow exiting the second stage is preferred at a temperature of 300 to 35O ° C in the third reaction zone, where it is brought into contact with a catalyst which is a metal from the group molybdenum and tungsten alone or together with one or more metals from group VIII contains. The metals of the catalyst are preferably chosen from the above list (Co-Mo, Ni-Mo, Co-V /, Ni-W). The metal

or the metals are deposited on a support which must have a sufficiently large specific surface, for example the specific surface is 120 to 500 in ² / g. As a carrier, one can choose, for example, the transition or eta-aluminum oxides or silicon oxide-aluminum oxide. It is preferable to use slightly acidic carriers (compare the ψ explanation given below). The reaction temperature within the third zone is between 300 and 39O ⁰ G; the total pressure fluctuates, for example

P.

between 10 and 60 kg / cm, preferably between 30 and 50 kg / cm «The rate of introduction of the charge (VVH) is preferably between 0.5 and 5 liters per liter of catalyst per hour, v / obci dos volume of the charge in the liquid State is gemoGccn. The hydrogen is introduced in such a way that the partial pressure at the level of the catalytic bed is preferred

between 8 and 25 kg / cm and the molar ratio hydrogen / Olefins is between 5 and 15.

The third stage catalysts can be used in their oxidized form using "both a single metal and

10988.7 / 1702.

BADORiGlNAL

also, a metal chip can be used. This stage is preferably carried out in the presence of a catalyst in sulphurized form, it being advantageous to work in the presence of such an amount of hydrogen sulphide that the molar ratio of hydrogen sulphide / hydrogen is between 200 and 4,000 ppm. The catalyst made of a single metal (molybdenum or tungsten) preferably has a proportion of 5 to 35 % of the metal (as oxide).

If the catalyst consists of at least one metal pair of the type mentioned above, the amount of molybdenum or tungsten (as oxide) is preferably between 5 to 50% by weight and that of the metals of group VIII (as oxide) is preferably between 1 and 6 %.

The weight of the metals is given as oxide, since these metals are generally in the form of metal compounds on the Carriers are precipitated, whereupon they are converted into the metal oxides by heating and then reduced and / or sulfurized.

The acidity of the carrier used in the various process stages can be caused by the heat of adsorption of ammonia

—4
the carrier can be measured at a pressure of 10 mm Hg. The heat of adsorption / \ H is calculated as follows:

. "Released heat (in calories per gram of carrier)

Z \ Xi = ' ^w ■ -: "^ ————. Ι -

Z \ Xi:

Amount of ammonia adsorbed (in millimoles NH, per gram of carrier)

These two measurements are made by microgravimetry and by a differential thermal analysis is carried out at the temperature at which the catalyst is used.

A support is said to be practically neutral or slightly acidic if Δ H is less than O ₁ OA- (catalyst support of the second stage). A support is said to be slightly acidic if Δ H is between 0.04 and 0.1 (catalyst support of

109887/1702

BATH

third stage).

Example 1:

One uses a gasoline batch following the steam cracking Composition:.

Paraffins and naphthenic iono-olefins

Diolefins and cycloolefins aromatics and alkenyl aromatics Total sulfur

8.6% by volume 10.4% by volume # ppm.

The reaction conditions are as follows:

1st stage

80 C

Temperature at the inlet of the reactor

¹¹ "Exit"'"180 ⁰ C.' The catalyst "consists of nickel, which is deposited on aluminum oxide (12.5 # nickel as oxide). The specific

2 surface is 70 m / g.

pressure
VVH ■

Molar ratio hydrogen /

Hydrocarbons

30th
2

0.5

2 * level

Temperature at the beginning of the reactor

I «I)

Al

Luogang ""

Scir.print ■
Poruial pressure reagent

Volume ratio of hydrogen sulfide / hydrogen

oil ratio hydrogen / olefins WH

280 ⁰ O

320 ⁰ C
43 kg / cia '15 kg / cm ^p

ppm 10
6 "

109887/1702

BPD ORIGINAL

~ ⁹ ~

Catalyst: cobalt

Molybdenum

carrier

5.7 wt. $ As CoO (0.076 moles of the oxide per 100 g of the catalyst)

5.7 & ew, - $, as MoO ₅

(0.040 moles of the oxide per 100 g of the catalyst),

Alumina

So there are 0.116 moles of metal oxide per 100 g of the catalyst precipitated with a specific surface area of 70 m / g. the This catalyst is sulfurized by pretreatment with a mixture of hydrogen sulfide and hydrogen.

The acidity test of the carrier gives a <Δ Η = 0.03

. step

Initial temperature '

Starting temperature.

Total pressure

Partial pressure of hydrogen 'V.V.H.

Volume ratio of water sulphide

substance / hydrogen Catalyst: cobalt

molybdenum

carrier

32O ⁰ G
340 G

43 kg / cm kg / cm *

1200 ppm

2.2% by weight, as CoO 12.2% by weight, as MoO ₇

y ff ^^

Aluminum oxide H = 0.07

The catalyst has a specific surface area of 300 m 2 / g. This catalyst is through a previous treatment with Hydrogen sulphide / hydrogen sulphurised. The properties the batch before and after the treatment are summarized in Table I with the corresponding result of a comparative example. · ·. . ·

BATH ORIGINAL

1 oaa's? / 1? 02

Comparative example IA:

The same batch as in Example 1 becomes a three-stage Subjected to hydrogenation treatment: The first stage is identical to that described in Example 1, but is used in the second Stage a platinum catalyst on aluminum oxide (1 wt Platinum); the catalyst has a very large specific surface area (220 in / g) and platinum is used in the metal form, In the third stage, a cobalt-molybdenum catalyst with a content of 2.2% by weight CoO and 12.1 wt .- # MoO_, which is based on the same aluminum oxide as in Example 1, This catalyst will be like Previously sulfurized as described in Example 1. The properties of the batch and final product are in the table below I reproduced,

TABLE I.

unit Batch 74 3example Example IA Ξ i properties % VoI, 27 30th End product End product Paraffins +
naphthenes - 8.6 774Q- 47 52 l'Ionoolefine 10.4 20th O O Diolefins +
Cycloolefins η - 54- O O Aromatics +
Alkenyl aromatics g / cm- ' 0.79 53 '- "48 Specific
Weight. . gBr- ₂ / 100g 66 3. 0.785 0.778. Bromine number mgMA / s 1 ■ 1 M.A.V. mg / 100 ml O O ilorzc before
act mg / 100ral 2 2 Resins poten
tially ppm 3 3.2 Gccamtschwe-
Tel., ■ ".... 4th 4th

109887/1702

BATH ORIGINAL

^! The BroEisahi was determined according to ASTM D 1159-61 -Tcet. MAV

means potassium anhydride value; the determination was carried out with the aid of the "UOP method 326-58". This to determine _the: tests used existing and potential resins are ASTK D 381-61 and ASTX D $ 87.

From the table it can be seen (bromine number and M.A.V.) that the hydrogenation of olefins is practical in both processes

\ is identical; However, the composition of the products obtained is different. In example 1, this is limited

■ Loss of aromatics in the hydrogenation to one unit, while in Comparative Example IA the loss is 6.

. The process according to the invention therefore provides a yield improvement of about 10 % compared to the known process.

·. on a product of similar quality.

• Packing example IB:

; The same batch as in Example 1 is a three-stage '. Subjected to hydrogenation using the same reaction conditions and the same catalysts; however, the Co-Mo catalyst used in the second stage has a very large specific surface area (220 m ² / g. The product obtained contains 51 vol- # aromatics and alkenyl aromatics (compared to 53 # in Example 1)

Verpjlcichs example IC:

A three-stage batch is carried out with the same batch as in Example 1 Hydrogenation by using the same reaction conditions and the same catalysts; However the volume ratio of hydrogen sulfide / hydrogen in the second reaction stage is equal to 100. The product obtained contains 51.5 vol .- # aromatics and alkenyl aromatics, furthermore 100 mg / 100 ml of resins, while in Example 1 the product contained only 2 mg / 100 ml of resins.

Example 2:

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109887/1702

The same batch is used as in the previous examples; the procedure differs from example 1 only by the Use of a sulfurized molybdenum catalyst (MoS ") an alumina carrier in the second sutfe. The specific Surface is 70 m / g. (This catalyst contains 16.6 wt. Molybdenum, as MoO- * <& «&. 0.116 fetch of the oxide.)

Kan receives the following values:

Composition unit Batch product Paraffins + naphthenes % Vol. 27 iionoolefine - 8.6 1.1. Diolefins + cycloolefins - 10.4 - Aromatics + alkenyl aromatics' - 54 53-5, specific weight g / cm ^ 0.793 0.7855 üroiu number £ Br ₂ / lQ0 g 66 1.8 S.A .. V. mg M.A ../ g ■ 74 0 Resins present mg / 100 ml 50 2 ¹¹ potentially mg / 100 ml 7740 2 · Total sulfur ppm 20th 5

When comparing these results with those of Example 1, it shows that the process with a molybdenum catalyst in the second stage goes very well; albeit the elimination of unwanted compounds »(03 efine and sulfur) is slightly less complete, the aromatics yield is better (loss of only 0.5 units).

/ Pat ent of sayings:

109887/1702

BATH ORIGINAL

Claims (1)

Claims Process for the selective hydrogenation of petroleum fractions, which boil in the range of gasoline and aromatic ■ Hydrocarbons, diolefins, olefins, as well as sulfur! contain compounds, characterized in that one - in a first reaction zone said batch in ; ■ liquid phase with hydrogen in the presence of a ! 'Treated hydrogenation catalyst, which is a metal of the VIII. Group contains, the products obtained in a second reaction zone j in the gas phase with hydrogen in the presence of a catalyst with a specific surface area of 20 "to 90 m / g traded, which contains at least one metal of the group molybdenum and tungsten, which are deposited on a carrier, - In a third reaction zone, the products obtained are treated in the gas phase with hydrogen in the presence of a catalyst with a specific surface area of 120 to 500 m ² / g, to which at least one metal from the group molybdenum is deposited. 2.) Process according to claim 1, characterized in that the catalyst of the third stage in sulfurized Shape is used. J.) Method according to claim 1, characterized in that that the second stage catalyst in sulfurized Γ, 'Form is v / ends. 4.) Method according to claim 2, characterized in that that so much hydrogen sulfide is introduced into the third reaction zone that the volume ratio Hydrogen sulfide / hydrogen is between 200 and 4000 ppm. 109887/170 2 ORIGINAL BATHROOM 5 ·) Method according to claim 3, characterized in that so much hydrogen sulfide is introduced into the second reaction zone that the volume ratio hydrogen sulfide / hydrogen is between 200 and 4000 ppm. 6.) Process according to claim 1, characterized in that the catalyst of the second stage is a metal from the Group contains molybdenum and tungsten and a Group VIII metal. 7.) The method according to claim 1, characterized in that the catalyst of the third stage is a metal from the Group contains molybdenum and tungsten and a Group VIII metal. 8.) Process according to claim 6, characterized in that the Group VIII metal used is nickel or cobalt. 9 ·) Process according to Claim 7, characterized in that the Group VIII metal used is nickel or cobalt. 10.) Method according to claim 8, characterized in that the catalyst of the second stage of 4 to 25 wt .-% of a molybdenum or tungsten compound (as oxide) and 2 to 15% by weight of a nickel or cobalt compound (as oxide). 11.) The method according to claim 9 »characterized in that the catalyst of the third stage from 4 to 25 wt .-% a molybdenum or tungsten compound (as oxide) and 2 to 15% by weight of a nickel or cobalt compound (as oxide) exists. 12.) Process according to claim 1, characterized in that the catalyst of the first stage consists of a metal of the Group VIII, which is essentially in metallic form. _{109887 / l702} BATH ORIGINAL