GB1584900A - Production of cracking catalyst - Google Patents

Description

(54) PRODUCTION OF CRACKING CATALYST (71) We, W.R. GRACE & CO., a corporation organized and existing under the laws of the State of Connecticut, United States of America, of Grace Plaza, 1114 Avenue of the Americas, New York, New York 10036, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: Hydrocarbon conversion catalysts which comprise inorganic oxide hydrogels and various quantities of zeolite and/or clay have heretofore been prepared by a variety of manufacturing techniques.

Typically, an alkaline sodium silicate slurried with a zeolite and/or clay and/or aluminate solution is mixed with a mineral acid or acid salt to form a precipitated inorganic oxide hydrogel catalyst composite. An aqueous slurry of the hydrogel may then be spray dried to form discrete spheroidal particles. The particles may be washed and/or ion exchanged to remove soluble sodium and sulphate ions and further fired and/or thermally treated to form active catalyst compositions.

United States Patent 2,384,946 to Marisic describe a method for preparing amorphous hydrogel particles which have catalytic cracking activity wherein a rapidly gelling silica hydrosol is sprayed into a fluid medium such as oil or air; and the sprayed sol particles gel or set to form particles of hydrogel.

United States Patent 2,428,895 to Shoeld discloses a method for making silica-alumina containing gels wherein separate streams of alkali metal silicate and aluminium sulphate are mixed upon a rotating surface and the reaction product is centrifugally dispersed in the form of gel particles.

In United States 3,867,308 to Elliott, a catalyst preparation method is disclosed wherein an acidic silica sol (partially gelled sodium silicate solution) is prepared which contains clay.

A zeolite component is slurried in acid solution, and then added to the silica sol. The resultant mixture is then immediately spray dried before gellation of the silica sol is complete to provide spheroidal catalyst particles which comprise clay and zeolite bound in a silica-hydrogel matrix.

While the above noted Marisic and Shoeld patents disclose the preparation of amorphous hydrogen catalysts by the spray forming of rapidly gelling silica and/or alumina sols, these references do not disclose the preparation of catalysts which contain substantial quantities of zeolite and/or clay solids. The Elliott patent describes a process for spray drying an acidic silica sol/zeolite containing catalyst before gellation occurs, Elliott does not disclose a process wherein a rapidly gelling zeolite containing catalyst mixture is formed by spray atomization and gellation occurs prior to any substantial drying of the catalyst particles.

It is an object of the present invention to provide an improved method for preparing inorganic oxide hydrogel bound catalysts in particulate form.

In the accompanying drawings, Figure 1 is a block diagram which sets forth a flow sheet that outlines a catalyst preparation method of the present invention; and Figure 2 is a cross-section view of a typical spray chamber and nozzle device which may be used in the practice of the present invention.

Broadly, our invention contemplates a process for preparing particulate inorganic oxide hydrogel zeolite/clay containing catalyst compositions wherein a basic alkali metal inorganic oxide slurry of zeolite and/or clay is combined with an acidic component to form a quick-gelling fluid mixture, and the mixture is immediately dispersed as droplets into a gaseous medium wherein the droplets gel to form discrete catalyst particles.

More specifically, we have found that microspheroidal catalyst compositions which contain at least 50% by weight and preferably 70 to 90% clay and/or zeolite may be prepared by an air-set technique which comprises the following steps: a) A basic, i.e. alkaline, slurry of an alkali metal silicate or aluminate or gellable mag nesium salt in aqueous solution, and zeolite and/or clay is prepared.

b) Said basic slurry is combined with an acid component comprising a mineral acid and/or acid salt to form a liquid mixture which gels rapidly, e.g. in less than 10 seconds.

c) The liquid mixture is dispersed before it gels in the form of droplets into a gaseous medium such as air and said dispersed droplets are permitted to gel, i.e. set to form cohesive inorganic oxide hydrogel particles with sufficient strength to be collected. They are suitably dispersed as droplets having diameters in the range 5 microns to 0.6 mm, and suitably they gel to microspheres having an average particle size of 50 to 75 microns.

d) The particles are collected and if desired, washed, ion exchanged and dried to produce a catalytically active composition.

A more clear understanding of our present invention may be obtained by reference to Figure 1 which represents a block flow sheet that sets forth the method of our invention. In Figure 1, block 1 represents an alkali metal inorganic oxide solution source, block 2 is a source of slurried zeolite, and block 3 is a source of clay. The blocks 1, 2 and 3 are interconnected to block 4 which represents a mixing tank in which the basic, i.e. alkaline, slurry component used in the process is prepared. Block 5 represents a source of the required acidic component. The blocks 4 and 5 are connected to block 6, which represents a spray chamber. The block 6 is connected to 7 which represents a washing and ion exchange step which in turn is interconnected to block 8 which depicts a drying step.

The spray drying chamber indicated as block 6 of Figure 1 is shown in greater detail in Figure 2. Reference to Figure 2 reveals a conventional spray chamber which comprises a spray drier shell 10 into which a supply pipe 11 enters along with a second supply pipe 12, which is placed coaxially within the supply pipe 11. As shown in Figure 2, the outer supply pipe 11 is used to convey basic component whereas concentrically located pipe 12 is used to convey acid component into the drying chamber. The supply pipes 11 and 12 are connected to a nozzle device, which is connected to the supply pipes 11 and 12 by means of nozzle body 13 and nozzle retainer ring 14. A nozzle mixing plate 15 is located above the nozzle orifice plate 16. The mixing plate 15 is provided with inlet holes 17 which are located around a centrally located inlet hole 18. It is noted that the centrally located inlet hole 18 is interconnected to the centrally disposed acidic component inlet pipe 12, whereas the outer inlet holes 17 are connected with the basic component supply pipe 11.

Between the mixing plate 15 and the orifice plate 16 an internal space 20 is defined in which mixing of the acidic and basic components takes plate. The orifice plate 16 is provided with a nozzle orifice 21 through which the mixed acidic and basic components are sprayed into spray chamber 25. The spray chamber device is provided with a gas inlet 26, and at the bottom, an exit opening 27 for gelled particles is provided.

To perform the method of the present invention a basic component is prepared which may comprise a solution of an alkali metal silicate and/or aluminate and/or gellable, soluble magnesium salts. The alkali metal aluminate, silicate, or magnesium salt is dissolved in water in amounts which range for example from 10 to 30% by weight SiO2, Al2O3 and/or MgO by weight of the solution. At this point the pH of the solution will range from 10 to near 14. A zeolitic component such as Type X or Type Y zeolite and/or clay is added to the solution of alkali metal silicate or aluminate. The clay and/or zeolite are present in the alkali solution in amounts to provide greater than 50%, and preferably 70 to 90% by weight of the finished catalyst.

The acidic component comprises a mineral acid such as sulphuric, nitric, hydrochloric acid, or optionally a solution which includes or comprises an acidic salt such as aluminium sulphate, i.e. acid alum. While it is contemplated that the present process may be conducted using an acidic component which comprises concentrated acid, i.e. substantially 100% acid, it is generally preferred that the acids be used in diluted form, that is acid solutions which contain from 18 to 35% by weight H2SO4, or acid and/or acid salts equivalent thereto. The acidic component normally willl have a pH of 0.1 to 3.0.

As shown in Figure 1, the basic and acidic components are combined within the spray chamber. As shown in more detail in Figure 2, the combining of the basic and acidic components occurs within a mixing spray nozzle. While the spray nozzle of Figure 2 may be conveniently utilized it is also contemplated that other nozzle configurations may be used such as the spinning disc type, which rotate at a high speed within a spray chamber and disperse droplets of fluid through radially disposed holes in the disc.

At the point where the acidic and basic components are combined, that is combined in mixing chamber 20 as shown in Figure 2, the mixing should occur as rapidly as possible.

Subsequent to mixing, the mixture of acidic and basic components, which comprises a rapidly setting hydrogel, is forced through the orifice 21.

Generally speaking, it is found that the time required from the point of mixing to the point of dispersing into the chamber 25 will be a fractional part of a second. In any event, the reaction conditions are selected so that the bulk of the gellation reaction occurs subsequent to dispersing into the atmosphere of the chamber 25.

The combined, basic and acidic components preferably will have a temperature of from 10 to 1800C. The atmosphere within the spray chamber 25 is selected so as to be conducive to gellation of the particle. In order to provide a suitable gaseous medium with the chamber 25, a gas such as air, ammonia, hydrogen chloride, carbon dioxide, nitrogen or mixtures thereof is provided through the conduit 26 at a temperature from 19 to 4000C and preferably at a relative humidity of from dry gas to nearly saturated steam. From the time the droplets of quick gelling mixture are dispersed through the orifice 21 to the time they are collected at the bottom of the chamber 25, the particles will proceed through substantially complete gellation. This will generally require from 1/2 to 30 seconds, during which the droplets are dispersed in and proceed through the gaseous atmosphere of the chamber 25.

By dispersing the gellable mixture into the atmosphere it is found that the particles formed are substantially spheroidal in shape. By governing the orifice size, wheel speed, the mixture viscosity, concentration, feed rate, and reactant ratio and the temperature at which the mixture is sprayed and gelled, it is found that the particle size of the product may be varied from 15 microns to as high as 0.6 millimetres.

Furthermore, it is found that by variation of the temperature, concentration, pressure and time parameters the physical properties of the product in terms of attrition resistance, density, surface area, and pore volume may be closely controlled within desired limits.

Subsequent to exiting from the spray chamber through outlet 28 as shown in Figure 2 the gelled particles are collected and if desired, further processed to yield catalytic compositions. Typically, the compositions prepared by our novel method may comprise catalytic cracking catalyst compositions having an average particle size range of 50 to 5 microns.

Ordinarily these catalyst compositions by weight will contain from 5 to 40% zeolite, i.e.

crystalline alumino-silicate, 20 to 75% clay and from 10 to 50% inorganic oxide gel matrix which binds the overall composition. The zeolite contained in the catalyst may typically comprise a Type X or Type Y zeolite which may be advantageously heat treated and/or rare earth exchanged as disclosed in United States Patents 3,449,070, 3,402,996, 3,293,192, 3,607 and 3,676,368 prior to incorporation into the catalyst. It is also contemplated that the sodium form of Type X or Y zeolite as disclosed in United States Patents 2,882,244 and 3,130,007 may be incorporated in the catalyst and subsequently exchanged with non-alkali metal ions such as rare earth, hydrogen, and/or ammonium. Furthermore, the clay component may comprise raw kaolin clay or thermally modified clay such as metakaolin. These catalysts are found to possess excellent attrition characteristics and are highly active for the catalytic cracking hydrocarbons.

In the present Specification the attrition resistance of the catalysts is expressed in terms of Davison attrition index (DI). The activity of the catalysts for the catalytic cracking of hydrocarbons is stated in terms of percent conversion. DI and activity is determined by standard procedures described and referenced in United States Patent 3,650,988.

The following specific examples illustrate preferred methods for the practice of the present invention.

EXAMPLE I Using a system such as outlined in Figure 1, 155 grams of sodium silicate solution which contains 28% by weight 3.25 Na2O.SiO2 was combined in a mixer with 80 grams of sodium Type Y zeolite, and 155 grams of clay. This mixture possessed a pH of 11.5 at 270C. In another container nitric acid was combined with water to provide a 23% by weight nitric acid solution. This solution possessed a pH of about 0.6. The alkaline component mixture and the acidic mixture were then heated to a temperature of about 28"C and pumped at a pressure of about 100 atmospheres through a mixing nozzle similar to that shown in Figure 2. The nozzle possessed an orifice of 0.1 millimeters. A spray chamber similar to that shown in Figure 2 was utilized in which air was circulated through the chamber at a temperature of about 100"C. The mixture of basic and acidic components was pumped through the nozzle at a rate of about 4 liters per minute. The droplets exiting from the nozzle required about 1.5 seconds to pass through the spray chamber. The collected gel particles were found to possess a particle size ranging from 62 to 71 microns. These particles were subsequently washed with water and ammonium sulphate to lower the soda content to about 0.45% Na2O, subsequently exchanged with a solution of rare earth chloride to impart a rare earth concentration of about 3.0%, and finally dried at a temperature of about 200"C. This composition which had a zeolite content of 14%, a clay.c.on.t nt of 66% and a silica gel binder content of 20% by weight was found to possess a Davison attrition index of 10 and an activity for the cracking of hydrocarbons of about 70.

EXAMPLE H To illustrate various operating conditions which may be used in the practice of the invention, a series of catalyst preparation runs were made using the general processing scheme set forth in Figure 1. A commercially available Niro spray machine was used to disperse the reaction mixture. The spray machine included a rotating disc which centrifugally dispersed the mixture at a speed of 12,000 to 15,000 rpm. through orifices having a diameter of 2.5 mm. The alkaline zeolite slurry was the same as in Example I and the reactants were at 260C prior to mixing. The flow rates (amounts) of the alkali and acid reactant streams were varied to obtain catalyst products which possessed the indicated pH when slurried 50% by weight with water. The spray formed catalyst products were exchanged with rare earth ions as shown in Example I to a level of about 3 to 4% by weight.

The catalysts contained about 14% by weight zeolite, 65% by weight clay, and 21% by weight silica gel binder. The catalyst possessed catalytic cracking conversion activity of about 71. The processing conditions and catalyst properties are summarized in the Table set forth below: TABLE Run Acid Acid Product Outlet Spray Surface Bulk NazO No. Concen- Slurry Chamber Air Area Density % by tration (% pH Temperature (m2/g) (g/cc) (g/cc) by weight) ( C) 1 HNO3 22 4.5 26 206 0.54 0.44 2 HNO3 22 4.5 65 156 0.68 0.58 3 HNO3 22 4.5 93 144 0.70 0.55 4 HNO3 22 4.5 150 164 0.75 0.57 5 HNOa 22 9.5 65 130 0.64 0.87 6 HNO3 22 9.5 93 127 0.66 0.70 7 HNO3 35 4.5 65 145 0.66 0.71 8 H2SO4 22 4.5 65 129 0.65 0.50 9 H2SO4 22 9.5 65 119 0.66 0.70 WHAT WE CLAIM IS: 1. A method for producing particulate hydrocarbon conversion catalysts comprising an inorganic hydrogel binder composited with at least 50% by weight zeolite and/or clay which comprises: (a preparing a basic slurry which comprises an aqueous solution of alkali metal silicate and/or aluminate and/or a gellable magnesium salt with zeolites and/or clay sus pended therein; (b) combining said basic slurry with an acidic component comprising a mineral acid and/or acid salt dissolved in water to produce a quick-gelling mixture; (c) dispersing said mixture before it gels into a gaseous atmosphere in droplet form. and permitting said dispersed droplets to gel to discrete particles of catalyst. and (d) collecting said discrete particles.

2. A method according to claim I wherein said basic slurry includes a member selected from the group consisting of Type X zeolite. Type Y zeolite. clay, and mixtures thereof.

3. A method according to claim l or 2 wherein said catalyst comprises from 70 to 90% by weight clay and/or zeolite.

4. A method according to any preceding claim wherein said discrete particles are washed and ion exchanged to remove soluble salts.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (18)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   binder content of 20% by weight was found to possess a Davison attrition index of 10 and an activity for the cracking of hydrocarbons of about 70.

   EXAMPLE H To illustrate various operating conditions which may be used in the practice of the invention, a series of catalyst preparation runs were made using the general processing scheme set forth in Figure 1. A commercially available Niro spray machine was used to disperse the reaction mixture. The spray machine included a rotating disc which centrifugally dispersed the mixture at a speed of 12,000 to 15,000 rpm. through orifices having a diameter of 2.5 mm. The alkaline zeolite slurry was the same as in Example I and the reactants were at 260C prior to mixing. The flow rates (amounts) of the alkali and acid reactant streams were varied to obtain catalyst products which possessed the indicated pH when slurried 50% by weight with water. The spray formed catalyst products were exchanged with rare earth ions as shown in Example I to a level of about 3 to 4% by weight.

   The catalysts contained about 14% by weight zeolite, 65% by weight clay, and 21% by weight silica gel binder. The catalyst possessed catalytic cracking conversion activity of about 71. The processing conditions and catalyst properties are summarized in the Table set forth below: TABLE Run Acid Acid Product Outlet Spray Surface Bulk NazO No. Concen- Slurry Chamber Air Area Density % by tration (% pH Temperature (m2/g) (g/cc) (g/cc) by weight) ( C) 1 HNO3 22 4.5 26 206 0.54 0.44 2 HNO3 22 4.5 65 156 0.68 0.58 3 HNO3 22 4.5 93 144 0.70 0.55 4 HNO3 22 4.5 150 164 0.75 0.57 5 HNOa 22 9.5 65 130 0.64 0.87 6 HNO3 22 9.5 93 127 0.66 0.70 7 HNO3 35 4.5 65 145 0.66 0.71 8 H2SO4 22 4.5 65 129 0.65 0.50 9 H2SO4 22 9.5 65 119 0.66 0.70 WHAT WE CLAIM IS: 1. A method for producing particulate hydrocarbon conversion catalysts comprising an inorganic hydrogel binder composited with at least 50% by weight zeolite and/or clay which comprises: (a preparing a basic slurry which comprises an aqueous solution of alkali metal silicate and/or aluminate and/or a gellable magnesium salt with zeolites and/or clay sus pended therein; (b) combining said basic slurry with an acidic component comprising a mineral acid and/or acid salt dissolved in water to produce a quick-gelling mixture; (c) dispersing said mixture before it gels into a gaseous atmosphere in droplet form. and permitting said dispersed droplets to gel to discrete particles of catalyst. and (d) collecting said discrete particles.
2. 2. A method according to claim I wherein said basic slurry includes a member selected from the group consisting of Type X zeolite. Type Y zeolite. clay, and mixtures thereof.
3. 3. A method according to claim l or 2 wherein said catalyst comprises from 70 to 90% by weight clay and/or zeolite.
4. 4. A method according to any preceding claim wherein said discrete particles are washed and ion exchanged to remove soluble salts.
5. 5. A method according to any preceding claim wherein said basic component has a pH

   of from 10 to near 14.
6. 6. A method according to any preceding claim wherein said acid component is sulphuric, hydrochloric or nitric acid, or aluminium sulphate, or a mixture thereof.
7. 7. A method according to any preceding claim wherein the acidic component has a pH of0.1 to 3.0.
8. 8. A method according to claim 7 wherein the time between combining the basic slurry with the acidic component and gelation of the droplets to particles is up to 10 seconds.
9. 9. A method according to any preceding claim wherein said quick-gelling mixture has a pH of 3.5 to 9.5.
10. 10. A method according to claim 9 wherein said quick-gelling mixture has a temperature of 10 to 1800C.
11. 11. A method according to any preceding claim wherein said quick-gelling mixture is dispersed as droplets having a diameter of 5 microns to 0.6 millimeters.
12. 12. A method according to claim 11, wherein said droplets gel to hydrogel microspheres having an average particle size of from 50 to 75 microns.
13. 13. A method according to any preceding claim wherein said particulate hydrogels comprise a fluid cracking catalyst composition which contains 5 to 40 percent by weight zeolite, 25 to 75 percent by weight clay, and the balance inorganic oxide hydrogel.
14. 14. A method according to claim 13 wherein said zeolite is a rare-earth exchange Type X or Type Y zeolite.
15. 15. A method according to claim 14 wherein said clay is kaolin.
16. 16. A method according to claim 1. substantially as herein described.
17. 17. Hydrogel particles comprising an inorganic binder and a zeolite and/or clay particles bound thereby. when made by a process according to any preceding claim.
18. 18. Use of particles according to claim 17 for cracking petroleum hydrocarbons.