DD281757A5 - METHOD FOR MODIFYING A CRACK CATALYST - Google Patents

Abstract

The invention relates to a process for modifying a cracking catalyst used in the catalytic cracking of hydrocarbons for gasoline recovery. The aim and object of the invention is to provide a process for the modification of a cracking catalyst, which enables a stabilization of the structure of the catalyst and a high activity and selectivity for the gasoline recovery. According to the invention, this is achieved by hydrothermally treating the catalyst in a water vapor-containing atmosphere having a water vapor content of 2 to 100 parts by volume at a temperature in the range of 373 to 873 K, until the surface of the catalyst is not more than 25% of its original Groesze shrinks and the lattice constant ao of the unit cell of faujasite is at least 24.45 Ao and at most 24.60 Ao and the number of aluminum atoms in the zeolite lattice is at least 30 per unit cell. The steam-containing atmosphere is generated by evaporating the moisture adhering to the catalyst in a reactor. {Cleavage Catalyst; Activity; Selectivity; Gasoline production; Columns, catalytic; hydrocarbons; Atmosphere, containing water vapor; Lattice constant; Unit cell; Water vapor content}

Description

28) 757

Title of the invention

Process for modifying a cracking catalyst

Field of application of the invention

The invention relates to a process for modifying a cracking catalyst used in the catalytic cracking of hydrocarbons for gasoline recovery.

Characteristic of the known state of the art

The cracking of high-boiling petroleum fractions is the most common method of significantly increasing the yield of gasoline in the processing of crude oil. Particularly effective for this are methods, - apply the catalysts, the yield of gasoline gas significantly increases when using zeol ?thhaltigen catalysts. Microspherical catalyst particles consisting of an amorphous matrix of refractory oxides, preferably alumina and silica, are most commonly used, the matrix containing up to 20% by weight of faujasite-type zeolite whose alkali ions have been wholly or partially exchanged by rare earth ions as well as binders. For a high yield of high-boiling petroleum fraction to gasoline fuel cracking catalysts are required, which have both a high splitting activity and a high selectivity for a liquid product in the range of Vergaseikraftstoff (C ₅ ⁺ - 180-220 ⁰ C), wherein the octane number (OZ) a particularly important quality measure for the carburetor fuel fraction of the cracked product. However, in practice cracking catalysts with the highest activity provide low octane gasoline fuels and vice versa (DE-OS-2 523 117). According to RM Masagutov "Aluminosilicate Catalysts and the Alteration of their Properties in Cracking of Petroleum Products" (Russ.) Moscow 1975 sink ¹ ; the yield of carburetor fuel - gasoline when heating various zeolite-containing cracking catalysts to 75O ⁰ C by one third and up to half. It has

dry air as ambient atmosphere still the least influence. Heating also has a particularly reduced activity in a steam atmosphere, a process which occurs when the catalyst is stripped in practical operation. Volume 10 of the Encyklopadie der technischen Chemie by Ulimann, 4th edition page 675 of 1975 describes that the matrix in which the zeolite content of the cracking catalysts is embedded plays a decisive role in the steam treatment. Thus, the activity of a pure rare earth-exchanged Y-zeolite (SEHY) drops from 67.8% to 6.3% when cracking a standard feed (Mid Continental Gasoil). If, on the other hand, only 10% of the same zeolites are incorporated into a matrix, the activity only decreases from 67.5% to 58.2% after steaming.

In US Patent 4,080,284 it is disclosed that the activity of a fresh cracking catalyst to the activity of a dampfbehandelteh as 94: _69} is measured as% conversion behaves. The yield of carburetor fuel decreases from 53 % by mass in the case of the fresh catalyst to 45 % by mass in the steam-treated.

Another positive effect of a steam treatment is described in US Pat. No. 3,257,310, in which the activity of a steam-treated zeolite catalyst is about twenty percentage points higher than that of a fresh comparative catalyst. A comparison of one and the same catalyst in the fresh and in the steam-treated state shows, however, that at a WIiISV of 2, the activity decreases from 75% in the fresh state to 53% after a 10-hour steam treatment. The specific surface area of the cracking catalysts according to US 3257310 is reduced by 20-80% in the steam treatment, depending on the steam temperature and the exposure time. The effect described also in the monograph by Venuto and Habib "Fluid Catalytic Cracking, with Zeolite Catalysts", Marcel Dekker Inc. New York 1979, that with reduced surface area, the cracking activity decreases, but the selectivity for the gasoline fraction increases , However, the yield of carburetor fuel decreases despite the increased selectivity. Recent invention descriptions such. EP 0 134 330 and EP 0 134 also describe an increased selectivity of zeolite-containing catalysts after a steam treatment. It deals

However, in the two E_rfindungsbeschreibungen but high-silicon zeolites of the ZSM series whose activity by a caused by the steam treatment incorporation of aluminum ions, which are derived from the Al ₂ O -, - increases binder. This process is confirmed by NMR measurements, as described in the invention description EP 0 134 333.

Object of the invention

The aim of the invention is to provide a method for the modification of a cracking catalyst, which ensures a high activity and selectivity of the catalyst for the gasoline recovery while maintaining a high octane number.

Explanation of the essence of the invention

The object of the invention is to develop a process for the modification of a CraPk catalyst which makes it possible to stabilize the structure of the catalyst used in comparison to the high hydrothermal loads during the reaction.

The object is achieved by the inventive method for modifying a cracking catalyst for gasoline production on the qasis a fresh faujasithaltigen, aluminosilicate catalyst of microspherical shape, achieved in that the catalyst in a steam-containing atmosphere with a water vapor content of 2 to 100 parts by volume in% at a Temperature in the range of 353 K to 873 K is hydrothermally treated until the surface of the catalyst shrinks by not more than 25% of its original size and the lattice constant a of the unit cell of faujasite at least 24.45 A ⁰ and at most 24.60 A and the number the aluminum atoms in the zeolite grid is at least 30 per unit cell.

It is also essential to the invention that the steam-containing atmosphere is produced by evaporating the liquid adhering to the catalyst in a reactor. The steam-treated microspherical catalyst according to the invention consists of an amorphous matrix of high-melt

For example, oxides preferably contain alumina and silica containing up to 20 % by weight of faujasite zeolite whose alkali ions have been wholly or partially exchanged by rare earth ions. It has been found that this catalyst has a special internal structure, which is that under a dense surface, which can be seen even at magnifications of 1: 10,000 in the scanning electron microscope, no coarse pore openings, a from leaflets of 2 - 20 pm kartenhausähnlictv built-up core or a submucosal spheres of 2 - 10 pm pomegranate-like shaped core is located.

The inventive mild Uasserdampibehandlung the catalyst causes a post-maturation of the zeolitic microcrystallites. takes place in the loose inner catalyst structure. The size and stability of the zeolite microcrystals increases, while the Si / Al ratio increases and the unit cell of the faujasite shrinks. The advantages of the mild steam treatment are that destruction of the zeolite is largely avoided and that it is sterilized by dealumination against other uncontrollable hydrothermal effects, without the number of active sites, which is determined by the number of Al ions in the Zeolite, is reduced too much. Higher possibilities of mild steam treatment according to the inventive solution are the introduction of steam or steam-air mixtures in vessels with the catalyst at a moderately elevated temperature.

With the solution according to the invention, for the first time it has been shown that the mild steam treatment of faujasite-containing aluminosilicate catalysts of microspherical form contributes substantially to increasing the activity, benzene selectivity and stability of the catalyst to the high hydrothermal loads during the reaction.

By increasing the stability, the process according to the invention guarantees a reduction in the catalyst consumption and, by increasing the activity and selectivity for gasoline, an increase in the yield of the target product of the cracking reaction.

The method according to the invention will be explained in more detail below with reference to exemplary embodiments.

EMBODIMENTS Example 1

100 g of a non-predried, commercial microspherical cracking catalyst with an inner pomegranate structure are kept in a covered crucible in a 10 cm high layer at 773 K for 5 h. This treatment gives a stabilized catalyst. This is subjected in a standardized test apparatus, a comparison test with a non-stabilized cleavage catalyst of the same type. The feedstock used is hydrogenated vaccine distillate (= HVD). For the test, 25 g each of the stabilized and non-stabilized catalyst are used. The catalyst / oil ratio (ratio of amount of catalyst to the amount of feedstock employed per test cycle) is 1.3 (test A) or 3 (test B). The reactor temperature is 775 K. The yields of. Gasoline, gas and coke are shown in Table 1.

Table 1 Sales Mass% in% Gasoline proportion in % Gas mass toil in% Coke Massean part in Vo B 5 Catalyst with pomegranate structure A B 44 50 A B 32 33 A 9 B 12 A 3 3 unstabilized 60 70 47 52 11 15 2 stabilized

* after 10 test cycles

Example 2:

100 g of a catalyst for deepening of higher boiling petroleum fractions, which has a Kartsnhausstruktur inside, B h at 750 K treated with superheated steam and so stabilized. The experimental conditions correspond to those in Example 1.

2 8 f757

The results are shown in Table 2.

yield

Catalytic converter Sales Gasoline Gas Coke with house of cards Massean- Massean- Massean- Masseanstruktur part in% toil% in% part in% part in%

Not stabilized 40 ' 45 31 32 7 9 2 4 Siert 61 74 47 51 12 19 2 4 stable lisiert

after every 10 test cycles.

Of the stabilized and unstabilized catalysts, the BET surface area and the lattice constant of the zeolite unit cell are determined before and after 10 test cycles. The result is the following: (Table 3)

Surface m / _g lattice constant d. unit cell

Catalyst with "Garnet apple structure" in front to test in front to test not stabilized 120 45 24.72 24.64 stabilized 105 95 24.55 24.52 Catalytic converter with "card house structure" not stabilized 166 30 24.77 24,60 stabilized 130 123 24,50 24.45

From the example '.st, it can be seen that unstabilized catalysts in the course of the cratering process undergo a very considerable surface shrinkage, due to the destruction of the zeolite, and this explains the greatly reduced activity. On the other hand, the partially dealuminated

2 θ f 75

Contacts - characterized by a shrinkage of the unit cell of the zeolite - stable active.

Claims (2)

817 5 claims A process for modifying a cracking catalyst for gasoline recovery based on a faujasithaltigen aluminosilicate catalyst of microsphere form, characterized in that the catalyst in a water vapor-containing atmosphere having a water vapor content of 2 to 100 parts by volume in% at a temperature in the range of 353 K 873 K hydrothermally treated wij. ^% D, until the surface of the catalyst to not more than 25% shrink inrer original size and the lattice constant a of the unit cell of faujasite at least 24.45 Å and not more than 24,60 A ⁰ and the number of aluminum atoms in the zeolite lattice least 30 per unit cell is , 2. The method according to claim 1, characterized in that the water vapor-containing atmosphere is generated by evaporating the moisture adhering to the catalyst in a reactor.