JPS6375092A - Production of high octane value gasoline from butane and/or 4c distillate occurring from cracking or catalytic reforming - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a process for the production of high-octane gasoline, a process made possible by a correct combination of steps. The initial feedstock is generally a butane fraction derived from, for example, a catalytic reforming unit or a catalytic cracking unit.

DESCRIPTION OF THE INVENTION The method according to the invention is suitable for refiners and/or refiners who own catalytic reforming equipment and/or catalytic clubking equipment.
or suitable for petrochemical companies, making it possible to attach higher value to the butane fraction, which is most often in excess.

The method according to the invention can be considered as follows.

Hydrocarbon fractions (usually pre-dried, desulphurized and denitrified and generally containing 4 carbon atoms per molecule, including isobutane and n-butane at this stage)
A fresh feed consisting mostly or entirely of paraffinic C4 fraction) is first sent to the dehydrogenation zone (step (a)) or isobutane and n-butane are at least partially butene and 2-butene) and 1,3-butadiene.

- The effluent withdrawn from the dehydrogenation zone of step (a) is then cooled by heat exchange with said fresh feed (step (b)) and then sent to the selective oligomerization zone (step (c)). . In this zone, the isobutene is mostly converted to high octane gasoline fraction.

The effluent withdrawn from the oligomerization zone of step (c) is preferably sent to a first fractionation zone (step (d)). In this zone, the following is recovered: - Hydrogen-rich α gas which also contains methane and ethane
Fraction. This fraction has a large proportion (i.e. at least 50% of the total ff1Et of said fraction)
% by weight, preferably at least 80% by weight) is recycled upstream of the dehydrogenation zone to help stabilize the dehydrogenation catalyst, and another portion is used internally in the refinery, e.g. in a hydrotreater. Can be: - Beta fraction containing mainly propane.

This fraction can be used, for example, as a fuel inside a refinery; - a gamma fraction containing in particular isobutane, n-butane, n-butene, butadiene and a small proportion of isobutene; and - a gamma fraction formed in step (c). A β fraction containing the high octane gasoline fraction. This is mostly at least 5
0% by weight, sent to high octane gasoline tank (pool). This beta fraction is preferably sent entirely to a high octane gasoline tank (pool).

More specifically, the β fraction coming out of step (d) is sent to the alkylation zone (step (e)). In this zone, at least a portion of the isobutane contained in this fraction reacts with the butenes to form alkylates that make excellent high octane gasoline for automobiles.

The effluent drawn off from the alkylation zone of step (e) is then sent, optionally after washing with water and/or decantation, optionally followed by a second
Drying is performed within the separation zone (step (f)). In this zone the following is recovered: - A fraction consisting essentially of n-butane and isobutane that did not react in step (e).

The fraction is largely (at least 50% by weight) recycled upstream of the dehydrogenation zone without separation from n-butane and isobutane. In this zone this fraction is mixed with the fresh feed and with the majority of the gaseous alpha fraction from step (d). The mixture is then sent to the dehydrogenation zone (step (a)). The fractions generally contain at least 95 ffiffi of isobutane and n-butane contained in the effluent leaving the alkylation zone under the conditions chosen for the fractionation.
% preferably at least 98% by weight. The entire fraction is preferably recycled to the dehydrogenation zone.

- A λ fraction containing said alkylate formed in step (e). This is mostly (at least 50% by weight)
Preferably all high octane gas tanks (pools)
It is a distillate rich in high-octane gasoline that is sent to In this gasoline tank, this fraction is in step (c)
(beta fraction from step (d)) formed in step (d).

The majority mixture of the δ and λ fractions results in a high octane gasoline fraction, which is recovered (in step (g));
In some cases, it is sent to a storage zone.

In the so-called dehydrogenation zone, the operating conditions are such that isobutane and n-butane are at least partially converted to isobutene and n-butene under conversion conditions close to thermodynamic equilibrium.

This dehydrogenation reaction occurs when the specific surface area is approximately 60 to approximately 4゜0I12.
/g of a preferably platinum-based catalyst supported on alumina and various cocatalysts.
Temperature of 0'C (preferably 550-600C), 0.0
It is carried out in the vapor phase under a pressure of 1 to IMPa (preferably 0.03 to 0.2 MPa) and a liquid hydrocarbon flow rate (space velocity) of about 1 to 1 O volume per hour per volume of catalyst. In order to ensure the stability of the catalyst, the hydrogen/hydrocarbon molar ratio at the inlet of the dehydrogenation reactor is preferably l/l -10ha.

The hydrocarbon feedstock used in the present process is a feedstock containing primarily hydrocarbons containing 4 carbon atoms. They are essentially free of hydrocarbons having 2 carbon atoms and generally contain at least 80% by weight, preferably at least 90% and most preferably at least 95% by weight of hydrocarbons having 4 carbon atoms. The remaining portion generally consists of hydrocarbons containing 3 carbon atoms and/or hydrocarbons containing 5 carbon atoms. Said hydrocarbons containing 5 carbon atoms generally account for less than 5% by weight, preferably less than 3% by weight, based on the weight of the feedstock. The feedstock used is generally at least 30% by weight of an isobutane-normal butane (n-butane) mixture, preferably at least 4off!, based on the total Tfffl of the feedstock. Contains n%. The feedstocks are typically dried, desulfurized and denitrified prior to their introduction into the dehydrogenation zone. The water, sulfur and nitrogen content of the feedstock introduced into the dehydrogenation zone is
Advantageously 50 ppm by weight and 10 ppm by weight each
and 5 F-m ppm or less, preferably about 10
Flea mppm52! Il amount ppa+ and 1wt pp11
It is as follows.

Among the various cocatalysts of platinum-based dehydrogenation catalysts supported on alumina, any cocatalyst familiar to those skilled in the art may be used. As examples of promoters, mention may be made of alkali and alkaline earth metals such as potassium, lithium, sodium, cesium, rubidium, barium, strontium and calcium. Similarly, gallium, indium, germanium, tin, zinc, mercury, steel,
Silver, gold, titanium, arsenic, antimony, bismuth, iridium, rhodium, ruthenium, atomic number 57-71
Rare earths such as lanthanum, and halogens such as chlorine can also be used. It is also possible to use several promoters at the same time. For example, at least one metal or metalloid different from the promoter halogen is preferably used in combination with at least one halogen, such as tin and chlorine.

In general, the catalyst contains, based on the alumina support, 0.05 to 5% by weight of platinum (calculated as metallic element), preferably 0.1 to 2% by weight of platinum, promoter metals and/or metalloids. 0.05 to 10% by weight (calculated as metal or metalloid elements), preferably 0.1 to 5% by weight of said promoter, most preferably 0.2 to 3% by weight, and even at least one halogen ( 0.1-10% by weight of halogen (calculated by weight of halogen), preferably 0.5-5% by weight of halogen, most preferably 0.5-2ffi
Including ffi%.

The so-called selective oligomerization reactions are generally carried out in the liquid phase, for example in the presence of an acidic catalyst arranged in fixed bed form. The conditions in the oligomerization zone are generally such that isobutene is reacted to a conversion of 80 wt.
ns2-butene) advantageously remains below about 3% by weight, preferably below 2% by weight, and very advantageously below 1% by weight. The oligomerization reaction is
Generally about 10 to about 250°C, preferably about 20 to 150°C
°C, advantageously at a temperature of about 50 to 100 °C, about 0.1 to 1
per volume of catalyst per hour under a pressure of 0 MPa, preferably from about 0.5 to about 2 MPa, advantageously from about 0.7 to about 2 MPa.
605-5, preferably about 0°1-4, advantageously about 0.
It is carried out at a liquid hydrocarbon flow rate (space velocity) of 2 to 2.5 volumes.

The catalyst used in this selective oligomerization reaction is selected from silica, alumina, silica magnesia and boron fist alumina. Furthermore, catalysts obtained by treatment of transitional alumina using acidic derivatives of fluorine, optionally with the addition of silicic acid esters, may be selected. Preferably, silica-alumina is used with a silica content of 60-95% by weight, optionally containing about 0.1-0.5% by weight of chromium oxide and/or zinc oxide.

Generally, the alkylation reaction is carried out in the presence of a dissolved catalyst, i.e., in the liquid phase or in the presence of a solid catalyst employed preferably in fixed bed form, at a temperature of about -20 to about +200°C and at a pressure of about 10 KPa to about 20 MPa. Performed under pressure. Therefore, in the liquid phase, in the presence of strong inorganic acids such as hydrofluoric acid or sulfuric acid, with or without the addition of Lewis acids such as boron trifluoride, antimony pentafluoride and also aluminum trichloride, and/or optionally may be operated in the presence of Brønsted acid. Furthermore, it is possible to carry out the operation in the vapor phase in the presence of a solid catalyst of the polyvalent metal phosphate, arsenate or stannate type to which boron trifluoride is added. Likewise, alkylations carried out in the presence of catalysts having a zeolite structure, with or without silica-alumina, e.g. optionally with at least one metal such as nickel, palladium, rhodium, platinum, etc. There are also methods.

More particularly, the alkylation reaction may be carried out at temperatures near ambient temperature and at moderate pressures.

During start-up of the unit, add isobutane supplement and
It is preferred to obtain a suitable isobutane/n-butene molar ratio at the entrance to the alkylation zone, preferably from about 6/1 to about 14 Ha.

This ratio yields an alkylate with optimal octane number.

The isobutane/n-butene molar ratio is preferably maintained at the above value in that zone during the entire operating time of the device.

The first fractionation zone generally consists of at least three fractionation columns. Generally, an alpha fraction is recovered at the top of the first column, a beta fraction at the top of the second column, a gamma fraction at the top of the third column and a beta fraction at its bottom. Second
A fractionation zone generally consists of at least one fractionation column.

Generally, a fraction is recovered at the top of this column and a λ fraction at its bottom.

The drawings show embodiments of the invention, but do not limit the invention to this particular embodiment. Those skilled in the art can make various modifications to the flowsheet of this drawing without departing from the scope of the invention.

A fresh feed of butane and/or C4 fraction is introduced into the apparatus via conduit (1). This is then passed from the top of the fractionation column (12) to conduits (1s) (14) and (2).
9) and the unconverted butane coming from the top of the fractionation column (27) via conduits (28) and (29). The resulting mixture is introduced via conduit (2) into the feed/effluent heat exchanger (3). Here the mixture is preheated and exits again via conduit (4). The preheated mixture passes through a furnace (5);
In this furnace the mixture is brought to the temperature required for the dehydrogenation reaction and then passed through the conduit (8) to the dehydrogenation zone (7).
) will be introduced. Upon leaving the dehydrogenation zone, the effluent enters the conduit (
8) and is introduced into the feed/effluent heat exchanger (3). Here this effluent is cooled to the temperature expected for the selective oligomerization reaction and then generally passes through conduit (9) to the selective oligomerization zone (after compression by compression means not shown in the drawings). 10). On leaving the selective oligomerization zone, the effluent is generally depressurized by means not shown in the drawings and then introduced via conduit (11) into a fractionation column (12). Separation tower (
At the top of 12), a highly hydrogen-rich hydrogen-methane-ethane mixture is withdrawn from conduit (13). Most of this mixture is recycled via conduit (14) towards the dehydrogenation zone. Another part is discharged via a conduit (15) towards a hydrogen treatment zone located, for example, in a refinery. Separation tower (
The product withdrawn at the bottom of the conduit (16)
) and sent to the separation tower (17). At the top of this column (17), a mixture consisting mainly of propane, propene and a small amount of isobutane is recovered, which is transferred to the conduit (17).
8) and discharge towards another area of the refinery. Here the mixture can be used as fuel for the furnace. For example, this mixture can be used to refuel the furnace (5) of the dehydrogenation zone. The product withdrawn at the bottom of the fractionation column (17) is sent via conduit (19) towards the fractionation column (20). At the bottom of this fractionation column (20), high octane gasoline is recovered and sent via a conduit (21) to a high octane gasoline tank (pool') (22).

If it is not desired to send all of the fraction recovered at the bottom of the fractionation column (20) to the high octane gasoline tank (pool) (22), a withdrawal pipe not shown in the drawing can be connected, for example, to the bottom of the fractionation column (20) or A side pipe on the conduit (21) is provided.

At the top of this fractionation column (20), isobutane, n-
recovering a mixture consisting of butane and C4 olefins;
This is sent via conduit (23) towards the alkylation zone (24). At the outlet of the alkylation zone, the distillate is washed, for example with water, and the by-products are discharged, for example by decantation, through conduit (25). After washing, decantation and separation of the by-products, the effluent is passed through conduit (26) to
Send it to the separation tower (27). At the top of this fractionation column (27), the mixture of isobutane and n-butane which has not been converted in the various steps of the process is recovered.

This mixture is preferably recycled in its entirety to the dehydrogenation zone via conduit (28). In this zone this mixture is
It is first mixed with the recycle hydrogen coming from the conduit (14) at the top of the fractionation column (12). The resulting mixture in conduit (29) is then mixed with the fresh feed in conduit (1).

If additional isobutane or a mixture containing isobutane is required, it is introduced into the alkylation zone via conduit (32). Such an introduction typically takes place, for example, during start-up of the device.

If the isobutane/n-butane mixture recovered at the top of the fractionation column (20) is not completely recycled to the dehydrogenation zone, a withdrawal pipe, not shown in the drawing, can be used, for example in the fractionation column (20).
27) or on a side tube on the conduit (28).

The majority of the alkylate withdrawn at the bottom of the fractionation column (27) is sent via a conduit (30) to a high octane gasoline tank (pool) (22). Here, this alkylate is mixed with the high-octane gasoline obtained by selective oligomerization which leaves the bottom of the fractionation column (20) via line (21).

The mixture of these two fractions, forming the superior high octane gasoline, is then sent via conduit (31) towards the storage zone.

If it is not desired to send all of the fraction recovered at the bottom of the fractionation column (27) to the high octane gasoline tank (pool) (22), a withdrawal pipe not shown in the drawing can be connected, for example, to the bottom of the fractionation column (27) or to the conduit. (30) Prepare for the upper side pipe.

EXAMPLES Example 1 A C4 feed having the following weight composition coming out of a catalytic reforming device is treated.

Isobutane: 44.94 n-Butane: 54.95 1-Butene: 0.11 The operating conditions in the various zones of the apparatus are as follows: l) Dehydrogenation zone (7): Catalyst: Platinum Ten tin + chlorine.

Support: specific surface area 162m2xg-', pore volume 0.58
gamma alumina support of cm3Xg-'. The catalyst contains 0.3% platinum, 0.8% tin and 0.8% chlorine by weight relative to the support.
including.

・Reaction temperature: 580℃ ・Space velocity: 4h-' ・Hydrogen/hydrocarbon: 3/1 (mol).

2) Selective oligomerization zone (10): Catalyst: 90
Silica alumina with wt% silica Reaction temperature: 60°C Pressure 1.2 MPa Space velocity: 0.5 h''''1 3) Alkylation zone (24): Catalyst: Hydrofluoric acid Reaction temperature 230℃ ・Pressure pressure 1.5 MPa ・Isobutane/n-butene ratio: 8/1 (mol) ・Hydrofluoric acid volume (8 per hour per unit of n-butene volume)
5% by weight): 2 - Acid/hydrocarbon volume ratio; 1 The mass balance table for the various zones of the entire apparatus is shown in Table 1. According to Table 1, when 100 kg of C4 feedstock from the reforming equipment is processed, at the end of this method,
It can be seen that the following net generation is obtained.

・Selectively oligomerized gasoline: 26.3 kg (pipe line (21) in the drawing) ・Alkylate: 64.4 kg (pipe line (21) in the drawing)
30)) 90. 7kg or 100k of raw materials
90.7 kg of high octane gasoline per gram.

This high octane gasoline has the following octane number:

・Single taste RON: 98 Working single taste MON: 90 Example 2 Catalytic cracking (Fluidized bed catalytic cracking - Flui
d Catalytic Crack i ng
: Treat the C4 fraction with the following weight composition discharged from the FCC equipment.

Isobutane: 33.80 N-Butane: 11.09 1-Butene: 14.95 Isobutene: 12.6B 2-Butene: 27.53 The operating conditions in the various zones of the apparatus were the same as in Example 1. Ta.

The material balance table for the various zones of the entire device is shown in Table 2. From Table 2, 100 C4 raw materials from the FCC equipment
It can be seen that when processing kg, the following net generation is obtained at the end of the method.

・Selectively oligomerized gasoline: 30.9 kg (Pipe (21) in the drawing) ・Alkylate: 59.1 kg (Pipe (30) in the drawing) 90 That is, 90 kg of high octane gasoline per 100 kg of feed material
It is.

This high octane gasoline has the following octane number:

・Single RON: 98.5 ・Single taste MON: 90.5 (Margin below)

[Brief explanation of the drawing]

The drawing is a flow sheet showing an embodiment of the invention. (12) (17) (20) (27)... Fractionation column, (3)... Heat exchanger, (5)... Furnace, (7)...
・Dehydrogenation zone, (lO)... selective oligomerization zone, (22)... high octane gasoline tank, (24
)...alkylation zone. Patent applicant: Institut Français du Betrole

Claims (10)

[Claims] (1) Contains at least 30% by weight of n-butane/isobutane mixture based on the total weight of the feedstock, 4 per molecule
A method for producing high octane gasoline from a hydrocarbon fraction containing essentially At least some of the isobutane and n-butane contained in the raw materials are replaced with isobutene, n-butane,
- converting the effluent to butene and 1,3-butadiene; (b) sending the effluent of the dehydrogenation zone (step (a)) to a heat exchange zone where the effluent is cooled by heat exchange with said fresh feed; (c) sending the cooled effluent from step (b) to a selective catalytic oligomerization zone so as to convert the isobutane contained in said effluent to a predominantly high octane gasoline fraction; , A method characterized by comprising the steps of: (2) Additionally, in step (d), the effluent from step (c) is sent to a first fractionation zone, where: an alpha fraction of the gas rich in hydrogen and containing methane and ethane; The fractions which are recycled towards the partial dehydrogenation zone are: - a β-fraction containing mainly propane, - a γ-fraction containing in particular isobutane, n-butane, n-butene, butadiene and a small proportion of isobutene, and - step (c) 2. The method of claim 1, wherein the δ fraction comprising the high octane gasoline formed in the fuel tank is recovered, the fraction being at least predominantly sent to a high octane gasoline tank (pool). (3) (e) sending the gamma fraction from step (d) to an alkylation zone where at least a portion of the isobutane contained therein is reacted with butenes also contained therein to form an alkylate; and (f) send the effluent of the alkylation zone (optionally after washing with water and/or decantation and optionally drying) to a second fractionation zone, in which: - the n that did not react in the previous step; - a κ fraction consisting essentially of butane and isobutane, said fraction being recycled for the most part upstream of the dehydrogenation zone, where this fraction is recycled from fresh said feed and said α from step (d); mixed with the majority of the gaseous fraction, said mixture then passing through the dehydrogenation zone (step (a))
and (g) a δ fraction containing said alkylate formed in step (e), which is at least predominantly sent to an octane gasoline tank (pool); 3. The method of claim 2, wherein a fraction of octane gasoline is recovered which is formed by a mixture of at least a major portion of the lambda fraction with at least a major portion of the lambda fraction. (4) The method according to any one of claims 1 to 3, wherein the new raw material is derived from a catalytic reforming device. (5) The method according to any one of claims 1 to 3, wherein the new raw material is derived from a catalytic cracking device. (6) The new feedstock contains at least 80% by weight of C4 hydrocarbons and at least 40% by weight of an n-butane-isobutane mixture, based on the total feedstock to be treated in the dehydrogenation zone. Claim 1
The method according to any one of items 1 to 5. (7) Process according to any one of claims 2 to 6, characterized in that at least 80% by weight of the alpha fraction obtained in step (d) is recycled to the dehydrogenation zone. (8) Claims 3 to 7, in which the entire κ fraction obtained in step (f) is recycled to the dehydrogenation zone 7.
The method described in any one of the following paragraphs. (9) During selective oligomerization step (c), step (b)
converting at least 90% by weight of isobutene contained in the effluent from the effluent into a high octane gasoline fraction;
A method according to any one of claims 1 to 8. (10) The selective oligomerization reaction is performed at a temperature of about 10 to 25
The process according to any one of claims 1 to 9, carried out at 0° C., a pressure of about 0.1 to 10 MPa, and a flow rate of liquid hydrocarbon of about 0.05 to 5 h per volume of catalyst per hour. Method.