JPH02225593A - Method for effective utilization of gas produced through catalytic cracking and method for reducing benzene content of gasoline - Google Patents

Abstract

Process for the production of petrol having a low benzene content and a high octane number, characterised in that a. a material discharged from a reforming reaction is fractionated into a light fraction enriched in benzene and a heavy fraction depleted in benzene, b. the said light fraction is reacted with a cracking gas containing at least one C2-C5 monoolefin, in contact with a dealuminised mordenite catalyst having an overall atomic ratio Si/Al greater than 20, so as to give an alkylated fraction and c. the said alkylated fraction is mixed with the said heavy fraction. Use of the resulting mixture as a fuel. <IMAGE>

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for the effective use of gases resulting from catalytic clubbing and a method for producing gasoline with a modified octane number of low benzene poverty.

PRIOR ART AND PROBLEM OF THE INVENTION The gases resulting from catalytic crabbing may be up to about 5% of the products coming from the p, c, c, equipment, but in practice they are Other than its internal use as a fuel, little or nothing is put to good use.

These gases generally consist predominantly of hydrogen, methane, ethane, ethylene and nitrogen, with carbon monoxide and carbon dioxide, propane, propene and small amounts of butane, butenes, pentane and pentenes. These gases contain monoolefins (ethylene, propene,
butene, pentene) is about 20 to 30ff1m%.

Therefore, in view of the large capacity of catalytic cracking units, it is very economically advantageous to convert these olefins into higher value added products.

On the other hand, legislators around the world, primarily in Europe, are rapidly trying to impose limits on gasoline, especially benzenepurate, for the sake of health administration. Probably < 199
From the beginning of 2000, the actually accepted limit content of around 5% will have to be severely reduced to at most 3%, and may even be lower.

The method according to the invention allows these two problems to be solved simultaneously. This method is therefore suitable for refiners that utilize catalytic reforming and catalytic clubking equipment simultaneously.

[Means for solving problems]

According to the method of the present invention, reformer 1 is separated into a benzene-rich light fraction and a benzene-poor heavy fraction, and the light fraction and a cracking product containing at least one 02-C5 monoolefin are separated. gas and mordenite I defined below.
The reaction is carried out in contact with a LII medium to obtain an alkylated fraction, and the alkylated fraction and the heavy fraction are mixed.

This alkylation reaction is carried out in the presence of an acidic zeolite catalyst arranged in fixed bed form at a temperature of 50-350°C (preferably 150-300°C), a pressure of 2-10 MPa (preferably 3-7 MPa), and a catalyst of 1 liquid hydrocarbon flow rate (space velocity) approximately 0.5 to IO volume per hour, benzene/
Olefin molar ratio 0.2-5 (preferably 0.6-1.
5).

Contained in catalytic cracking gases by oligomerization in the liquid or heterogeneous phase, in the presence of catalysts formed by the action of alkyl aluminum and nickel salts, or nickel-based catalysts supported on silica-alumina. Efforts have already been made to utilize the olefins contained in catalytic cracking gases by converting them into gasoline or jet fuel. In both cases, carbon monoxide (e.g. 0.1-2
% by weight) is very troublesome. This is because carbon monoxide is a poison to nickel-based catalysts due to the formation of nickel carbonyl. The use of such catalysts therefore requires an expensive preliminary separation by cryogenic physics of the lightest fractions of the feedstock (hydrogen, CO1COmethane).

In contrast, the zeolite catalyst used in the present invention, dealumination mordenite with an overall Si/Al atomic ratio of more than 20, preferably 30-75, treats the gases resulting from catalytic cracking without any pre-separation. can do. These gases may contain carbon monoxide, for example 0.1-2ffi%.

Several zeolite catalysts have already been proposed for the alkylation of benzene with ethylene, on the one hand, and with propene, on the other hand.

In 1975-1980, the use of H-type zeolites, in particular Mobil's 23M5 (EPO 104729), was proposed.

More recently, other zeolites, particularly cusa alone or together with faujasite.

436.432), some mordenites have been proposed, in some cases with Group 1 metals supported (US 3.85L, 004). Japanese patent (JP
58-218121i and JP5g-159427>
contains metal ions such as Mg, KSCa, low S
Single mordenite with i/A/atomic ratio (4,5-5) or H1 type (JP041670) is recommended.

Additionally, dealuminated mordenites and processes for their preparation are known: EP-0084748, I
EP-0097552, EP-0196965 (small pore mordenite) and PR-87/12932° These mordenites were used to convert methanol or to isomerize olefins.

These mordenites are preferably prepared as follows for best results.

In the first step, the non-decomposable cations, generally Na", present in the starting mordenite are removed. To do this, it is necessary to remove the non-degradable cations present in the starting mordenite. The important point is that after this first step, which may be called decationization, almost all of the alkali cations have been removed (Na % is between 150 and 11000 p).
pi, preferably from 300 to 800 pp■), and the solid obtained is substantially undealuminated (% dealuminated 10%, preferably 5%), H-type or H-type precursor (NH4゛) It is to become. Preferably, the Nu + type shall be chosen as the H type precursor.

In the second step, the H-type or H-type precursor, which is hardly or never dealuminated, is heated at a temperature of 450°C.
or more, for example 450 to 650°C, preferably 550 to 6
Subject to steam treatment at 00°C.

The water content ff1 (volume f:L) of the firing atmosphere is advantageously 20
% or more, preferably 40% or more.

At the end of this second step, a solid is obtained which is characterized by the presence of a small amount of amorphous zones, which are precursors of a secondary porous lattice, and by a crystalline framework that is almost free of structural defects. The presence of amorphous zones in zeolites treated under high temperature and steam is a known phenomenon. However, the recommended operating conditions make it possible to limit the proportion of amorphous zones in the crystal to the greatest extent possible. The crystallinity determined by X-ray diffraction is generally 80% or more, more specifically 90% or more. Solids calcined under steam are also characterized by the presence of extra-reseau aluminum species within the structural pores and therefore require a subsequent acid attack. This is because most of these micropores are clogged. However, in order to obtain a good alkylation catalyst according to the invention, this acid attack must be exploited to the fullest.

Acid attack is the third step in this catalyst preparation.

At this stage, it is important to preserve or release the strong acid sites in the solid. The acid attack must therefore be strong enough, on the one hand, to remove the strong site poison, cationic aluminum, formed during the steam treatment, and on the other hand, to liberate the structural pores. Since the Brønsted type acidic sites attached to the lattice fence are of moderate or weak acidity, it is not essential to carry out their complete removal. However, the acid attack must not be too strong to avoid too much dealumination of the framework aluminum. The acidity retained due to acid erosion is a characteristic obtained after calcination under steam,
In particular, it is closely related to the crystal lattice. Si/Al ratio is 1
Acid solution (HC/SH
So HNO3, etc.) concentration 24ゝ0.5 to 5N, preferably 1 to 3N. If the skeleton has a higher St/Al ratio, the acid solution concentration is 5 to 20N.
1 Preferably 7 to 12N shall be used (S of the skeleton
The t/Al ratio is determined by infrared spectroscopy for ratios lO~40 and by 29S1 N, M, R,
).

Additionally, in order to obtain high S f /A / ratios, i.e. S t /A / ratios above 40, more particularly above 60, advantageously multiple cycles of calcination under steam-acid attack are used. You may.

The solids prepared according to the invention have an overall Si/At atomic ratio of 20 or more, preferably 30-75. These are 2755A 1-2730A"CIA-10-"
m), preferably 274OA' to 2735A1
has a grid volume of These preferably have structure A/-
The OH has sufficient acidity to interact with weak bases such as ethylene (infrared measurements at 77° C.) or weakly acidic compounds such as H2S (infrared measurements at 25° C.).

Furthermore, these solids should preferably be free of extralattice cationic species. These species were measured using the magic angle rotation technique at 21 A/N,
M, R, spectrum, Oppm (control A/(H20
) 63゛)
) (Width at half height is 5 pp- or less, preferably 2
pp- or less).

The method according to the invention can be envisaged as follows: - Formation coming from a contact reforming device;
First, it is separated in a distillation tower. At the bottom of the column, e.g. 85
The benzene-bubbled fraction with a boiling point above °C is collected. This is sent to a reservoir. At the top of this distillation column, the light reformate, e.g. The effluent of the alkylation section is then brought to the reaction temperature by simultaneous heat exchange with and passage through the furnace and then sent to the alkylation section containing the mordenite catalyst;
It is sent to a stripping column and at the top a light fraction consisting of hydrogen, carbon monoxide, carbon dioxide, nitrogen, oxygen, methane and ethane is taken off. This may be discharged towards the flame, but rather it may be used as fuel in the preheating furnace of the feed going to the alkylation section;
The fraction extracted from the bottom of this stripping column is sent to a stabilization column, and at the top, a light fraction rich in propane and butane is taken out. This is,
P, G, can be sold in (liquefied petroleum gas) form; - The gasoline fraction withdrawn from the bottom of this stabilizer column is sent to a storage vessel where approximately 85 Mix with fractions with boiling point above °C.

The drawings show special embodiments of the invention.

A conduit (1) sends the formate leaving the catalytic reforming device to a distillation column (2);
Collect the fraction with a boiling point of 85°C or higher at the bottom of the
This is sent via conduit (3) towards storage tank (4). At the top of the distillation column (2), a temperature of 85° C. is applied via conduit (5).
A fraction with a boiling point below is taken off and mixed with the gas arriving from the catalytic cracking device via conduit (8). The resulting mixture is then sent via conduit (7) to a heat exchanger (8) and then via conduit (9) to a preheating furnace (
10) and finally via conduit (11) to the inlet of the alkylation reactor (12). At the outlet of the alkylation reactor (12), the effluent is introduced by a conduit (13) into a heat exchanger (8) and then exiting from this heat exchanger, this effluent is passed through a conduit (14) into a Sent to ripping tower (15). This stripping tower (1
5) At the top of hydrogen, carbon monoxide, carbon dioxide,
A mixture of nitrogen, oxygen, methane and ethane is removed and is either discharged via line (I6) towards the flame or sent via line (17) towards the preheating furnace (10) of the alkylation section where it is May be used as fuel. The product is withdrawn at the bottom of this stripping column (15) and is sent via line (18) to the stabilization column (19). At the top of the stabilizer column (19), a mixture consisting of propane and butane is recovered and discharged via a conduit (20) towards a storage of liquefied petroleum gas (LPG) and subsequently commercialized. This stable tower (19
), the gasoline is extracted from the bottom of the pipe (21
) to the storage tank (4), where this gasoline is
A conduit (
3) with the fraction boiling above 85°C. The resulting mixture is removed via conduit (22). This is a gasoline fraction with low benzene poverty and high octane number.

EXAMPLES The following examples illustrate the invention but do not limit its scope.

Example IA Three catalysts B1, B2, B3 are prepared.

The raw material used to prepare these various catalysts is a small-pore mordenite from Société Simique de Grande Barrois, designated A11tc 150. Its chemical formula in anhydrous state is N a ,
A/02 (S io 2 ) 5.5, its benzene adsorption capacity is 1% by weight relative to the dry solid weight, and its sodium content is 5.3 ff1m%. 500 g of this powder are immersed in a 2M ammonium nitrate solution and the suspension is brought to 95° C. for 2 hours. The volume of ammonium nitrate solution introduced is four times the weight of dry zeolite (V/P-4). This cation exchange operation is repeated three times. After the third ion exchange, the product was washed with water at 20°C.
Wash with V/P-4 for 20 minutes.

The sodium content in weight percent relative to the dry zeolite varies from 5.5% to 0.2%. The product is then filtered and the various lofts are subjected to calcination under a closed atmosphere at more or less elevated temperatures depending on the degree of skeleton dealumination desired (Table 1). The firing time is fixed at 2 hours. The water vapor partial pressure inside the reactor is about 9026.

After this calcination step, the crystallinity of the various solids is 90% or more.

Each solid is then subjected to an acid attack using a higher concentration of nitric acid during the previous step, the greater the dealumination rate obtained in the framework (Table 1). During the acid attack, the solids are refluxed in a nitric acid solution for 2 hours using a V/P-8. The product is then filtered and washed with a large amount of distilled water.

The S i /A /atomic ratios obtained for each solid are listed in Table 1.

Each modified solid is then shaped by kneading with an aluminum mold binder in the proportion of 20 parts by weight of binder and then passing through a die.

The resulting extrudates with a diameter of 1.2+ am are then dried and calcined in temperature steps of about 1 hour at 150-550°C.

Table I (Margin below) 1 After firing Hayashi After acid erosion Example IB Three catalysts B'l, B'2, and B'3 are prepared.

These catalysts differ from those described in Example IA in the following ways. In other words, the raw materials used to prepare these were Al1t (not mordenite called 3150, but TO called TSZ 800 NAA) from Grand Baroise, a manufacturer of Sochete-sha Simic de Jars.
It is large-pore mordenite made by YO-8ODA. The chemical formula of this in anhydrous state is Na, Al
02 (Sin2) 50, and its sodium content is 5.7%.

All steps of ion exchange, calcination, acid attack, shaping and calcination are carried out under the same conditions as described in Example IA. The St/Al atomic ratios obtained differ only very slightly (Table ■).

Table after calcination and forest acid erosion (blank below) Example 2 Three catalysts B1, B2, prepared in Example IA
B3 was tested for alkylation of the top fraction (boiling below 85° C.) of the formate exiting the catalytic reforming device with the gas exiting the catalytic crabking device.

Before fractionation, the liformate had the weight composition and characteristics shown in Table 1.

After that, this reformate was added to 0lde of 80 theoretical plates.
The following 2
Two fractions were collected: - 32% by weight of the total glue formate at an initial temperature of ~85°C.
Fractions: 85° C. to end point fraction of 68% by weight of the total glue formate.

The main characteristics of these two flats are also shown in Table ■.

The gas coming out of the contact crabking device had the following composition (wt%): φHydrogen: 1.3G Carbon monoxide (co): 0.51% carbon oxide (cO
2) : 0.17 ・Nitrogen: 5.50 Monomethane: 28.52 Qethane: 20.90 Monoethylene: 19.30 ・Propani 3.55 ・Propene: 17.75 ・Butane: 1.50 ・Butene: 2.50 - Pentane: 0.43 (blank below) Table ■ Table ■ The operating conditions used for the alkylation reaction are as follows Knee temperature: 260°C φ pressure; 4.5 MPa - 1 times the weight of the catalyst Weight flow of liquid reformate ff1
(initial point ~85 °C fraction) (initial point of rifformate ~85 °C) Benzene/olefins (c2+03+04) molar ratio -0,82 After 120 hours of fractionation after leaving the reactor, 3 catalyst Bl ,
The products obtained for B2 and B3 are shown in 4 tables each.
It had the main characteristics shown in.

Inspection of the results shows that it is preferable to operate with the catalyst recommended by the present invention and to use dealuminated mordenite with an overall St/Al atomic ratio of 30 to 75. Mordenites with a solid, overall St/Al atomic ratio of less than 80 are clearly less selective and they result in the formation of paraffins (methane, ethane, propane, butane and pentane). Mordenites with an overall SL/AI atomic ratio of 75 or higher are slightly more selective, but less active. This is because the olefins (ethylene, propene, butene, pentene) contained in the raw materials are not completely converted.

In the case of catalyst B2, the product obtained at the bottom of the stability column (19) of the diagram was mixed with the fraction withdrawn at the bottom of the distillation column (2) of the same diagram.

104 kg of gasoline were obtained in this way. That is a 4% yield increase.

This gasoline had the following characteristics: Density at 20°C: 0.790 ◆^STM distillation curve Cooking curve at 23°C 30% by volume near 1°C 50% by volume: 116°C 70% by volume: 149 @0 90g amount %: 178 'C 95 volume %: I91" (End point "C: 21g" (.

・Octane number is 98 instead of 95 for the original formate. ・Gasoline benzene poorer is 8.62% by weight to 3.
It decreased to 19 times ffi%. That is a decrease of 63%.

Example 2B Three catalysts 13'l, B' prepared in Example IB
2 and B'8 were also tested under the same operating conditions and using the same raw materials as Ijt81S82 and B3. The results obtained, shown in Table V, are very similar to those obtained with catalysts old, B2 and B3. As in the case of Example 2, the overall SL/Al
It has been found that it is preferable to carry out the operation with mordenite having an atomic ratio of 30 to 75.

(Margin below) Table V

[Brief explanation of the drawing]

The drawing is a flow sheet showing an embodiment of the invention. (2)... Distillation column, (4)... Storage tank, (8)...
・Heat exchanger, (10)... Preheating furnace, (12)...
- Alkylation reactor, (15)...Stripping column, (19)...Stabilizing group. Patent applicant: Institut Français ψ du Betrole

Claims (5)

[Claims] (1) A method for producing gasoline having a low benzene content and a high octane number, comprising: (a) fractionating the reforming effluent into a benzene-rich light fraction and a benzene-poor heavy fraction; (b) ) said light fraction and at least one C_
2-C_5 monoolefin-containing cracking gas in contact with a dealuminated mordenite catalyst having an overall Si/Al atomic ratio of 20 or more to obtain an alkylated fraction, and (c) said A method characterized in that the alkylated fraction and the heavy fraction are mixed. (2) A method according to claim 1, wherein the cracking gas contains 0.1 to 2% by weight of carbon monoxide. (3) Mordenite is produced by: 1) Treating mordenite H or NH with a gas containing water vapor at a temperature of 450 to 650°C; 2) Treating the product of step 1) with an acid having a concentration of 0.5 to 20N. 3. A process according to claim 1 or 2, wherein the product is a product produced from . (4) A method according to claim 3, wherein the starting mordenite is small-pore mordenite. (5) The overall Si/Al atomic ratio of mordenite is 30~
75. A method according to one of claims 1 to 4, wherein the method is 75.