WO1999002260A1

WO1999002260A1 - Catalyst composition comprising a molecular sieve and an aluminium phosphate containing matrix

Info

Publication number: WO1999002260A1
Application number: PCT/EP1998/004980
Authority: WO
Inventors: Avelino Corma
Original assignee: Shell Internationale Research Maatschappij B.V.
Priority date: 1997-07-11
Filing date: 1998-07-08
Publication date: 1999-01-21

Abstract

A catalyst composition comprising a particulate acidic molecular sieve material and a matrix material containing amorphous aluminium phosphate, wherein the atomic ratio of Al to P of the aluminium phosphate is in the range of from greater than 1.0 to 1.5. The catalyst composition may be used as a fluid catalyst cracking catalyst.

Description

CATALYST COMPOSITION COMPRISING A MOLECULAR SIEVE AND AN ALUMINIUM PHOSPHATE CONTAIN^¬ ING MATRIX

The present invention relates to a catalyst composition including zeolite material, which catalyst composition is suitably used in a hydrocarbon conversion process such as fluid catalytic cracking or hydrocracking of hydrocarbon-containing feedstocks .

Such a catalyst is described in USA patent specification No. 4 873 211. This publication discloses that a suitable, steam-stable catalyst composition comprises particulate zeolite material and a matrix material containing amorphous aluminium phosphate, which matrix material is furthermore free from alumina and magnesia. The known amorphous aluminium phosphate is obtained from precipitated aluminium phosphate gel. The atomic ratio of Al to P of the aluminium phosphate gel is preferably in the range of from 0.9 to 1, and according to the example the atomic ratio of Al to P of the aluminium phosphate is 0.96.

There is a need to improve the activity of the catalyst according to USA patent specification No. 4 873 211 while preferably maintaining the desired steam stability of this catalyst.

Applicant has now found that a more active catalyst composition is obtained when extending the atomic ratio of Al to P into the super-stoichiometric domain. An additional advantage is that the steam stability is not negatively influenced by altering the catalyst composition of the prior art catalyst according to the invention. Steam stability, or the ability to be stable under the influence of steam, is an important feature of catalyst compositions. For example, in regenerating catalyst of a fluid catalytic cracking process it is inevitable that the catalyst composition is contacted with steam at elevated temperatures, which, as is generally known, affects the retention of the zeolite material . The catalyst composition according to the present invention comprises a particulate acidic molecular sieve material and a matrix material containing amorphous aluminium phosphate, wherein the atomic ratio of Al to P of the aluminium phosphate is in the range of from greater than 1.0 to 1.5.

USA patent specification No. 5 194 412 discloses a fluid catalytic cracking catalyst composition consisting of a zeolite and an aluminium phosphate matrix. The Al to P mol ratio may be between 0.4 and 1.4. The examples illustrate a Al to P mol ratio of 0.68 and 1. A difference with the present invention is that only highly crystalline aluminium phosphate is disclosed in this document. Applicant has found that improved steam stability is obtained when an amorphous aluminium phosphate matrix is used.

The acidic molecular sieve to be employed in the process of the present invention is suitably any known crystalline microporous acidic hydrocarbon conversion catalyst or mixtures thereof. Preferably the molecular sieve comprises a shape selective material having pore dimensions suited for the selective conversion of a desired feedstock, more preferably having pore dimensions in the range 0.3-0.9 nm. Examples of suitable crystalline microporous acidic hydrocarbon conversion catalysts having pore dimensions in the range 0.7 to 0.9 nm include faujasite type zeolites, for example zeolites Y and X, for example in stabilised (i.e. zeolite USY) , zeolite beta and zeolite omega. Examples of suitable crystalline microporous acidic hydrocarbon conversion catalysts having pore dimensions in the range 0.3 to 0.7 nm include crystalline microporous silica (silicalite) , silicoaluminophosphates such as SAPO-5 and SAPO-11, aluminium phosphates such as ALPO-11, titanium aluminophosphates and -silicates such as TAPO-11 and TASO-45, boron silicates and crystalline (metallo) silicates such as ferrierite, erionite, theta and the ZSM-type zeolites such as ZSM-5, ZSM-11, ZSM-12, ZSM-35, ZSM-23, and ZSM-38 wherein the metal may comprise aluminium, gallium, iron, scandium, rhodium and/or chromium, and mixtures thereof. Preferably the acidic molecular sieve is a crystalline alumina silicate (hereinafter referred to as zeolite) , as for example described above. Preferably the zeolite is in its acidic hydrogen form. Preferably, the atomic ratio of Al to P of the amorphous aluminium phosphate is larger than 1.01. More preferably the atomic ration is larger than 1.05. A suitable range is from 1.1 to 1.5, preferably from 1.15 to 1.5 and more preferably from 1.15 to 1.4. Most preferably this ratio is smaller than 1.35.

Suitably the mass ratio of zeolite material to amorphous aluminium phosphate is in the range of from 0.4 to 20.

The BET surface area of the catalyst composition is preferably between 40 and 400 m^/g.

The catalyst composition of the present invention may further include fillers, such as clays, silica and alumina, a binder, such as alumina sols and silica sols and other materials for example alumina. The catalyst composition may furthermore comprise promoters for example LaP04 or LaAlPC>4.

The catalyst composition can be suitably prepared by any standard method. Examples of such methods are described in G.M. oltermann, J.S. Magee, S.D. Griffith, in "Fluid Catalytic Cracking Science and Technology", J.S. Magee and M.M. Mitchell, jr., Stud. Surf. Sci. Catal., Vol. 76, Elsevier, Amsterdam, 1993, p. 105-145.

The aluminium phosphate can be added during preparation of the catalyst in any suitable form, for example as a gel, a suspension, a sol or a solid, preferably by slurrying with the zeolite. The particle sizes of the catalyst composition are preferably in the range which is suitable for fluid catalytic cracking, which is suitably in the range of from 20 to 120 micrometer.

The catalyst composition according to the present invention containing a precipitated amorphous aluminium phosphate matrix can be used after it has been dried, for example spray dried. Alternatively the catalyst composition can be subjected to calcining under normal conditions, suitably at a temperature of between 400 and 900 °C in the absence of steam. The catalyst composition according to the invention may also be subjected to a hydrothermal treatment, for example by steaming the particles at a temperature of between 400 and 900 °C. The catalyst may be used for a number of applications, suitably hydroconversion applications, for example hydrocracking, catalytic dewaxing and isomerisation of paraffinic feedstocks. Preferred applications are processes which involve a steam regeneration of the catalyst. More preferably the catalyst is as a fluid catalytic cracking catalyst. Examples of such a fluid catalytic cracking process are described in Catalytic Cracking of Heavy Petroleum Fractions, Daniel DeCroocq, Institut Francais du Petrole, 1984 (ISBN 2-7108-455-7) .

The invention will now be described in more detail with reference to the below non-limiting examples. Example 1

The catalyst compositions used in the examples consist of particulate zeolite material dispersed in an amorphous aluminium phosphate matrix material .

The precursor of the matrix material is an aluminium phosphate gel. An aluminium phosphate gel was prepared as follows, a mixture of 13.58 g AICI3.6H2O, H3PO4 and 211.5 g of bi-distilled water was stirred and stored at 0 °C for 1 hour, wherein the amount of H3PO4 was so selected that the required atomic ratio of Al to P of the aluminium phosphate is obtained. To this mixture was added an aqueous ammonium solution (10%) at a rate of 60 ml/h until the pH was in the range of from 5 to 6.

The final sample was washed with isopropanol and dried in air at 100 °C.

In order to determine the effect of calcining the aluminium phosphate gel, the gels were calcined at 450 °C or at 650 °C for 5 hours. The BET surface areas of the calcined samples are given in Table 1.

Table 1. BET surface area of calcined aluminium phosphate matrix .

From Table 1 it can be concluded that under these conditions super-stoichiometric aluminium phosphate has a larger surface area. Example 2 To prepare a catalyst composition, particulate zeolite material was dispersed in the aluminium phosphate gel which had been stored for 10 hours at room temperature. Aluminium phosphate gels with different atomic ratios of Al to P were prepared by adjusting the mass ratio of phosphoric acid.

The zeolite material used in the experiments was prepared as follows. Particulate NaY zeolite (CBV-100 from PQ) having a particle size of about 20-50*10^"^ m was treated to exchange about 80 %m of Na⁺ by NH4Α Thereafter the ion-exchanged material was calcined with 100% steam for two hours at 500 °C to obtain an ultra stable Y zeolite having a unit cell size of 24.53*10^~10 m (to be referred to as USY-24.53) . The sample was twice exchanged with ammonium chloride and calcined at 500 ^CC to reduce the Na⁺-content to below 0.20 %m. Subsequently the sample was dispersed in a gel of aluminium phosphate.

To prepare a catalyst composition, particulate zeolite material was dispersed in the aluminium phosphate gel. The final sample was washed with isopropanol and dried in air at 100 °C. The dried powder was crushed, pelletized and sieved at 0.59-0.84 mm, and finally calcined at 650 °C and thereafter the samples were steamed at 750 °C for 5 hours (100% steam) . Table 2 gives the unit cell size of USY-24.53 as the zeolitic material in the sample after steaming, wherein the mass ratio of zeolite material to aluminium phosphate was 0.5. Table 2. Unit cell size after steaming at 750 °C for 5 hours .

The unit cell size of the samples with an Al/P atomic ratio of less than 1 could not be determined, this could be attributed to the formation of tridymite.

From Table 2 it can further be concluded that for super-stoichiometric amorphous aluminium phosphate the unit cell size of the zeolite material is retained at a level which is above that of the control (without ALPO4 ) . Example 3

In order to determine the cracking activity the following experiments were carried out in an automized Micro Activity Test unit, which allowed cyclic experiments to be carried out, this means that the full cycle of stripping-reaction-stripping and regeneration was done. The conditions were: time on stream 30 s; reaction temperature 520 °C; cat/oil ratio 0.70-2.50 g/g; gasoil feed 2.14-0.60 g; and regeneration at a temperature of 525 °C for 3.5 hour.

The amount of catalyst was 3.00 g, and the feed was a vacuum gasoil having properties as set out in Tables 3a and 3b . Table 3a. Properties of vacuum gasoil used in the experiments .

Table 3b. Distillation curve ASTM D1160 (in °C)

Table 4 gives the activity as the total conversion for a catalyst composition comprising USY-24.53 and aluminium phosphate as prepared in accordance with above- described method. The mass ratio of USY-24.53 to aluminium phosphate was 0.5, and the control did not contain aluminium phosphate. The total conversion is the total yield as percentage of the feed, wherein the total yield is the amount of gases, gasoline, lco plus coke. Table 4. Total conversion (in %) for the catalyst compositions of the invention compared to a catalyst composition with no aluminium phosphate ( Αontrol' ) as a function of the catalyst-to-oil mass ratio.

Table 4 shows clearly the significant improvement in activity of the catalyst composition of the present invention .

Table 5 gives the second order kinetic rate constant for a catalyst-to-oil ratio of 1.5 as a function of the Al to P atomic ratio for a catalyst composition comprising USY-24.53 and aluminium phosphate, wherein the mass ratio of zeolite material to aluminium phosphate is 0.5. The comparative experiment is done with USY-24.53 with no aluminium phosphate ( ^λcontrol' ) . The second order rate constant is equal to x/(l-x), wherein x is the total conversion as defined above. Table 5. Second order kinetic rate constant as a function of the Al to P atomic ratio.

From Table 5 can be concluded that the catalyst compositions according to the present invention with the super-stoichiometric amorphous matrix perform better than the catalyst compositions not according to the invention.

Separately it was found that the total conversion of an amorphous aluminium phosphate matrix with no zeolite material is less than the total conversion obtained for thermal cracking, this suggests that the aluminium phosphate matrix itself has no catalytic activity. Therefore the effect discussed with reference to Tables 4 and 5 originates from an unexpected interaction of the zeolite material with the aluminium phosphate matrix. Example 4

To illustrate the improvement of the present invention when another zeolitic material is used, the above described micro activity tests on the gasoil as described for Example 3 were carried out with a catalyst composition including zeolite-beta in place of USY-24.53. The catalyst compositions were prepared as described above with reference to the catalyst compositions including USY-24.53. The mass ratio of zeolite-beta to aluminium phosphate was 0.5, and the control did not contain aluminium phosphate. The activities as total conversions are given in Table 6. Table 6. Total conversion (in %) for the catalyst compositions of the invention containing zeolite-beta compared to a catalyst composition with no aluminium phosphate ( Αontrol' ) as a function of the catalyst-to- oil mass ratio.

Table 6 shows clearly the significant improvement in activity of the catalyst composition with zeolite-beta of the present invention.

Claims

C L A I M S

1. A catalyst composition comprising a particulate acidic molecular sieve material and a matrix material containing amorphous aluminium phosphate, wherein the atomic ratio of Al to P of the aluminium phosphate is in the range of from greater than 1.0 to 1.5.

2. Catalyst composition as claimed in claim 1, wherein the atomic ratio of Al to P of the aluminium phosphate is greater than 1.01.

3. Catalyst composition as claimed in claim 2, wherein the atomic ratio of Al to P of the aluminium phosphate is greater than 1.05.

4. Catalyst composition according to any one of claims 1-3, wherein the atomic ratio of Al to P of the aluminium phosphate is smaller than 1.35.

5. Catalyst composition according to any one of the claims 1-4, wherein the mass ratio of the acidic molecular sieve material to aluminium phosphate is in the range of from 0.4 to 20.

6. Catalyst composition according to any one of claims 1-5, wherein the acidic molecular sieve material is a zeolite, preferably in its acidic hydrogen form.

7. Use of a catalyst according to any one of claims 1-6 in a hydroconversion process.

8. Use according to claim 7 wherein the catalyst is used as a fluid catalytic cracking catalyst.