NL8103069A - METHOD FOR PREPARING CATALYTIC CRACKING CATALYSTS - Google Patents

Description

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Process for the preparation of catalytic cracking catalysts

The invention relates to the preparation of catalytic cracking catalysts, in particular to aluminum-exchanged type Y zeolite containing catalysts, with which high octane cracked gasoline can be prepared.

Cracking catalysts with zeolite promoters, which give J gasoline at significant yields in the catalytic cracking of petroleum gas oil feeds, have been used commercially for years.

Canadian Patent 81 * 8966 discloses a catalytic cracking catalyst containing a thermally stabilized type Y zeolite, containing Z144S, which can be exchanged for a variety of metal cations, including aluminum ions. The gasoline fractions prepared with ZiMJS zeolite-containing cracking catalyst have good octane numbers.

U.S. Pat. Nos. 3,293,192, 3,375,065, 3.12,996,33,0,070 and 3,595,611 describe processes for preparing thermally stabilized type Y zeolites, such as Z11 * US zeolite. The process described in these patents 20 typically includes exchanging a counter-sodium type Y zeolite / ammonium ions, calcining and further ammonium / metal cat exchange.

US patent 3.1 * 55.81 * 2 describes the preparation of an ammonium / aluminum exchange type Y zeolite, which is used in the preparation of catalytic cracking catalysts.

The zeolite-containing cracking catalysts prepared by known methods yield significant yields of cracked gasoline. However, it is often observed that very active rare earth exchanged zeolite cracking catalysts produce large amounts of medium octane gasoline. In contrast, hydrogen-exchanged zeolite catalysts, which are "particularly selective for the" preparation of high octane gasoline fractions, often exhibit lower activity.

Accordingly, it is an object of the invention to provide a catalytic cracking catalyst that is both highly active and selective in the preparation of high octane gasoline.

Another object is to provide a process for the preparation of commercial amounts of zeolite promoted cracking catalysts capable of cracking petroleum feeds. with high conversion rate to achieve significant yields of high octane gasoline.

A further object is a thermally stable, highly active, aluminum-exchanged type Y

zeolite which contains very low levels of sodium ions.

Yet another object is to provide an economically feasible process for preparing aluminum-exchanged thermally stabilized zeolites that have a particularly low sodium content.

These and other objects of the invention will become apparent from the following detailed description and examples.

Broadly speaking, the invention contemplates the preparation of novel catalytically active aluminum-exchanged crystalline alumino-silicate type Y zeolites which can be used for the preparation of active cracking catalysts which are selective for high octane gasoline.

More specifically, it has been found that improved gasoline selective zeolites can be prepared by the following method.

(1) a sodium type Y zeolite (NaY) is exchanged with an ammonium salt solution to lower the soda (NagO) to below about ^ percent by weight.

81 0 3 0 6 9 - 3 - (2) the ammonium exchanged zeolite (NH 2 NaY) is calcined at a temperature of 538 to 815 ° C.

(3) The calcined zeolite is then reacted with an acid aluminum salt solution and a pH of about 3.1 to 2.0 to decrease the soda content of the zeolite to below about 0.8 wt.%.

The zeolite prepared by this method can be combined with an inorganic oxide matrix, either after the acid-aluminum salt exchange, that is, after step (3), or after calcination, that is, after step (2). When the calcined zeolite from step (2) is combined with a matrix, the combined calcined zeolite / matrix mixture is subjected to an acid-aluminum-15 salt solution treatment.

The sodium type Y zeolite used in the invention has a silica / alumina ratio of from about 5 to 2 and a unit cell size of from about 2U to 60 to 65. Typical soda Y zeolites contain from about 20 to 22% by weight alumina (Al 2 O 3), 68 to 65% by weight silicon dioxide (SiO 2) and 13 to 12% by weight sodium (Na 2 O). Sodium type Y zeolites are easily obtained from commercial sources.

The sodium salt solution used to reduce the sodium level of the initial sodium Y zeolite is preferably ammonium sulfate. However, solutions of ammonium chloride or ammonium nitrate can be used. An ammonium salt solution typically contains from about 3 to 10 weight percent of the salt dissolved in water. The ammonium salt solution is contacted with the sodium Y zeolite 30 for a period of about 10 to 120 minutes, preferably at the temperature ranging from about 60 to 100 ° C to achieve the desired level of soda removal, i.e. reduction of the Na 2 O content to below b%, preferably to below 3% by weight. Typically the sodium Y ^ 35 zeolite is contacted with from about 1 to 3 batches of 8103069 - 1 »-

V

the ammonium salt solution.

Following contact with the ammonia salt solution, the NaNH 2 Y zeolite is heated, i.e., calcined, at a temperature of about 538 to 815 ° C.

Preferably, the calcination takes place over a period of about 120 to 180 minutes, using conditions where the zeolite is kept in a self-steaming condition. During the calcination step, the initial unit cell size of the sodium Y zeolite is reduced by about 0.2 S, that is, the unit cell size of the calcined zeolite will be in the range of from about 2h5 to 2U, 52 lb.

The calcined zeolite is then subjected to treatment (exchange / reaction) with an acid-aluminum salt solution. Preferably, the saline solution is aluminum sulfate, which has been acidified with enough sulfuric acid to obtain a pH of about 3.7 to 2.0, and preferably 2.7. Although aluminum sulfate is the preferred acid salt, aluminum chloride or aluminum nitrate can be used with suitable hydrogen chloride or nitric acid additions.

As a result of contact with the acidic aluminum salt, the remainder of the residue sodium ions present in the calcined zeolite are exchanged for aluminum ions.

Preferably, the contact with the acidic aluminum salt is repeated using successive fresh baths of aluminum salt solution until the sodium content of the zeolite is reduced to below 1% by weight Na 2 O and preferably below 0.8% wt% Na 2 O 2. As a result of this exchange step, the unit cell of the calcined zeolite is 2.52 to 2ktk5. In addition, it is noted that as a result of the above-described process, the alumina content of the zeolite is from about 23 to about 13% depending on the pH of the exchange slurry. It is further noted that when aluminum oxide is removed from the zeolite, the total surface area of the zeolite, which is initially 650 m / g, is increased. This indicates, i). 35 that the total crystalline structure of the zeolite is intact ...

\ 81 0 3 0 6 9 ** _ - 5 - remains. In many cases, zeolites subjected to calcination and acid exchange conditions lose crystallinity.

Following the exchange with the aluminum salt-5 solution, the zeolite is subjected to exchange with an ammonium salt solution, typically ammonium sulfate. This ammonium sulfate exchange results in further sodium removal to form a zeolite composition containing less than about 0.5 weight percent Na 2 O 2.

The zeolites prepared by the above-described process are advantageously combined with an inorganic oxide matrix to obtain highly active gasoline-selective cracking catalysts. Typically, the matrix component contains clay and an inorganic oxide binder such as silica, alumina, silica-alumina sols, and silica, alumina, silica-alumina gels. Combining the zeolite with the matrix component can be accomplished by the methods described in U.S. Pat. Nos. 3,957,689, 3,867,308, and 3,912,619. Hydrocarbon cracking catalysts containing the zeolite of the present invention contain from about 30% to 50% by weight of zeolite, from about 5% to 35% by weight of clay, and the rest inorganic oxide sol or gel binder. Furthermore, the catalysts may contain components such as aluminum oxide and small amounts of platinum, which result in the preparation of catalysts that control carbon monoxide oxidation and / or sulfur emissions from the catalytic cracking process. Furthermore, the new aluminum thermally exchanged zeolites of the invention can be combined with other zeolites such as rare earth exchanged and type 7 zeolites to obtain a catalyst with multiple zeolite promoters.

The catalysts obtained by using the new zeolite are very active. In addition, the catalysts are capable of forming gasoline fractions, which have an unusually high octane number when the catalytic cracking process 81 0 3 0 6 9 - 6 - high is performed at a relative / conversion, i.e. from about 60 to 70 % conversion. The gasoline fractions obtained with the present catalysts have an octane rating of about 90 to 91 research and about J8 to 79 engine.

The invention will be illustrated in the following examples.

Example I

(a) a sodium type Y zeolite (NaY) was exchanged with ammonium sulfate solution to obtain a sodium / ammonium type Y zeolite (Na, NH ^ Y), containing 3.55 wt.

Na ^ O contained. The Na, NH ^ Y was heated at 1250 ° E for 3 hours to obtain a calcined Ha, NH ^ Y, which has the following properties: 2 area - 757 m / g 15 crystallinity - 97% of standard unit cell - 2h, h9 S SiOg - 71.99 wt / S AlgOs - 23,% by weight (b) The calcined Na, NI, Y zeolite, prepared 20 in (a), was treated with a 0.05 M aluminum sulfate solution for 1 * 5 min. at a pH of 3.3. This product was then exchanged twice with a dilute ammonium sulfate solution to obtain a zeolite having the following properties: crystallinity - 89% of standard 25 NagO - 0.26 wt.

SiOg - 73, wt. $

AlgO2 - 23.62 w / s

(c) A second sample of the calcined Na, NH 4, Y prepared in (a), was treated with a 0.05 M aluminum sulfate solution for U 5 min at pH 2.6 and 95 ° C, followed by two exchanges with dilute ammonium sulfate solution.

The zeolite obtained has the following properties: crystallinity - 105% of standard

NagO - 0.25 wt%% SiOp - 80.6 wt%, AlgO ^ - 16.1 wt ^

P

81 03 0 6 9 - τ -

Example II

(a) A sample cracking catalyst was prepared and evaluated for cracking activity, which sample contained HO% by weight of the zeolite prepared in Example I (c). The catalyst comprises a clay / silica-alumina sol matrix, which contained 35 weight percent clay and 25 weight percent silicon dioxide. The catalyst sample, after treatment with 20% steam for 12 hours at 1520 ° F, had the following properties.

After „0 - 0.17% by weight ^ 2 10 area - 258 m / g pore volume - 0.22 cc / g Η ,, Ο pore volume - 0.02 cc / g microactivity * - 67.5 voi., % conversion unit cell - 2U, 22% ^ * Determined at 16 wt. hour space velocity.

3 catalyst / oil ratio at 900 ° F.

(b) A catalyst sample was prepared by combining percent by weight of the calcined Na, NH 4 Y zeolite of Example I (a) in the matrix described in (a). The catalyst was spray-dried and then washed with water at 140 ° F. 10 pounds of the washed catalyst was rinsed three times at 100 ° F with? Diluted 10 pounds (3 ° Be ').! ? ammonium sulfate solution at pH 5. The catalyst was then washed with dilute ammonium hydroxide solution at pH 7.5 · 2 ^ (c) A catalyst sample was prepared by a method similar to that in (b) above. However, after washing with water, 10 pounds of the catalyst were mixed with 35 pounds of aluminum sulfate solution containing 0.5% by weight Al 2 O 3. The exchange took place at pH 2.7 and 140 ° F. The catalyst was then washed with 10 pounds of dilute ammonium sulfate solution at pH 5. The catalyst was slurried again with 3 pounds of the aluminum sulfate solution and finally washed with dilute ammonium hydroxide solution.

(d) A method similar to that described in (c) was continued. However, after washing with water, 10 pounds of 81 0 3 0 6 9

-e _ V

8 of the catalyst rinsed three times with 3 ¾ pounds aluminum sulfate solution containing 0.5 wt. # ΑΙ ^ Οβ at a pH of 2.6. The catalyst was then washed with dilute ammonium hydroxide solution at a pH of 7.5 · The catalysts prepared in (b), (c) and (d) of Example II had the following properties: Catalyst (Example) II (b) 11 (c) Ill (d) total volatiles (wt.) 10.20 11.03 10.33

Na20 (wt. #) 0.k2 0.21 0.78 10 area (m ^ / g) 195 203 200 microactivity (# conversion} 65, k 68.7

Example III

To illustrate the octane-enhancing selectivity of the catalysts of the invention, a sample of the catalyst prepared in Example II (c) was compared with a sample of the non-aluminum sulfate-exchanged catalyst of Example II (b), The following liquid cracking catalyst pilot unit data was developed at bO w, hour space velocity, catalyst / oil ratio at 950 ° C after deactivating the catalysts with 20 # steam at 1520 ° F for 12 hours: catalyst (example) 11 (c) 11 (b) conversion, vol. % 62.0 62.0 C5 + petrol, vol.? » fresh food 52.5 5, 0.025 octane number

Research 90.3 88, U

Engine 78.9 77.9

Light Cycle oil, vol. # Fresh food 25.9 26.5

Coke, wt. # Fresh food 2.7 2.7

From the above data, it can be concluded that the aluminum sulfate-exchanged catalyst of the invention (Catalyst 11 (c)) gives gasoline of higher octane than the non-aluminum sulfate-exchanged catalyst (Catalyst 11 (b)).

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Claims (11)

A process for the preparation of a catalytically active crystalline alumina desilicate zeolite comprising: (a) exchanging a sodium type Y zeolite 5 with an ammonium salt solution to reduce the soda content of the zeolite to below about 4% by weight Na 2 O; b) Calcination of the ammonium exchanged zeolite at a temperature of about 537 to 815 ° C; and (c) reacting the calcined zeolite 10 with an acidic aluminum salt solution to decrease a pH of about 2.0 to 3, · νοοΓ from the sodium content to below about 9% by weight Ka 2 O. 2. Process according to claim 1, characterized in that the silica / alumina ratio of the sodium zeolite varies from about U7 to 5 * 2. Process according to claim 1, characterized in that the ammonium salt is ammonium sulfate. A method according to claim 1, characterized in that the aluminum salt is aluminum sulfate. Catalytically active crystalline aluminum oxide silicate zeolite obtained by the process according to claim 1. The zeolite of claim 5, wherein the zeolite has a unit cell of about 24.45 to 24.52 units and an aluminum content of about 20 to 22% by weight. Al ^ O ^ and a surface greater than 650 m / g. Catalyst composition containing the zeolite of claim 5 mixed with an inorganic oxide matrix. Catalyst according to claim 7, characterized in that the zeolite contains from about 30 to 40% by weight of the catalyst. Catalyst according to claim 7, characterized in that the matrix contains clay in an inorganic oxide binder selected from the group consisting of silicon dioxide, aluminum oxide, silica-alumina sols and gels. A process for catalytic cracking of hydrocarbons for obtaining high octane gasoline fractions comprising contacting the hydrocarbons at catalytic cracking conditions with the catalyst of claim 7 Process according to claim 10, characterized in that the catalyst is a fluid cracking catalyst. 81 0 3 0 6 9