CA1103226A - Hydrosol and catalyst preparation - Google Patents

Abstract

Abstract of the Disclosure Titania-alumina-silica hydrosols are prepared by reacting titanium and aluminum salts with an alkaline metal silicate solution at a pH of about 3. The hydrosol compositions may be dried to form inorganic-titania-alumina-silica gels or the hydrosols may be used as inorganic binders for the preparation of catalyst compositions which may contain clay and zeolites.

Description

~32Zti This application relates -to the preparation of inorganic hydrosols and more particu].arly to -ti-tania-alumina-sillca hydrosols which find utility as binders for catalytic composi-tions.
Catalyst compositions used for the conversion of hydrocarbons comprise finely divided inorganic materials such as clay and crystalline aluminosilicate zeolites bound toge-ther into discrete particles which may range from about 20 microns to 6 millimeters in size. These catalys-t particles must have a pore structure which permits entry of reactant molecules into the catalyst particle,. At the same time the catalyst particles must have physical strength and density characteristics which permit their extended use under commercial hydrocarbon processing conditions.
In the past many methods have been suggested for the preparation of commercially useEul hydrocarbon conversion catalysts which in some instances contain hydrosol binders.
- U.S. 3,867,308 to Elliott describes the preparation of petroleum cracking catalysts wherein a composite of clay and zeolite is bound together with an acidic silica hydrosol.
` U.S. 3,957,689 to Ostermaier et al. discloses a process for preparing catalysts in which a buffered silica-alumina hydrosol is combined wi-th clay and zeolite and subseque~tly spray dried.
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U. S. 4,022,714 to P.llio-tt describes a tikania or zirconia-silica hydrosol which is used i.n the preparation of zeoli-te/clay containiny c.racking catalysts.
It is an object of the present invention to provide an lmproved inorganic hydrosol which may be used as a binder in the manufacture of catalyst compositions.
It is a further object-l:o provide a hydrosol binder which may be used to prepare dense physically strong composites of clay and zeolites.
These and still fur-ther ob~ec-ts of the present invention will become clearly apparent to one skilled in the art in the following detailed description and drawing wherein the figure sets forth a flow diagram of the process used to prepare hydrosol in catalyst compositions as the present invention.
Broadly my inveDtion contemplates an inorganic :
hydrosol composition which comprises ti.tania alumina-silica hydrosol dispersed in aqueous media, and catalytic compositions which utilize the hydrosol às a binder.
More specifically, I have found that a titania-alumina-sil.ica hydrosol which is particularly useful for -the preparation of bound clay/zeolite catalyst compositions may.be prepared by combining mixed acid salt solutions of titanium and aluminum with alkali metal silicate solutions to form hydrosols having a pH of from about 2.5 to 3.5. The weight ranges of titania, alumina, silica and water in tlle hydrosol expressed ln terms r~ parts by weight ~l2~

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l`iO2 and A12O3 per par-t by weight SiO2 are as Eollows:
II2O = 6 to 25 parts per par-t SiO2 TiO2 = 0.01 to 0.12 parts per part SiO2 A12O3 = 0.01 to 0.15 parts per part SiO2 When the hydrosol binder is converted to a dried gel product,~it contains the following amount of SiO2, Tio2 and A12O3 expressed as percent by weight on a dry basis:
SiO2 = 78 to 98 TiO2 = 1 to 10 A12O3 = 1 to 12 When the presently contemplated hydrosols are used to prepare zeolite/clay containing catalytic cracking catalysts, from about 15 to 35% by weight (dry basis) of the hydrosol is comblned with from about 5 to 60% by weight zeolite and from about 5 to 80% by weight clay or other welghting agents such as alumina, silica- :
alumina, and silica.
The titanium salts used in the preparation of the hydrosols are soluble titanium salts, preferably soluble titanyl sulfate having the formula:

Tio SO4 H2SO4 8H2O or Ti(S4)2 ~ 9H2O
The aluminum salt lS preferably acid aluminum salts such as aluminum sulfate. The alkali metal silicate used in the preparation of the hydrosols is preferably sodium.silicate which has.a composition from 3.36 to

2.5 SiO2:Na2O whlch may contain from about 5 to 20%
by weight of the aforementioned sodium silicate dissolved ~ .
in water.
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32;~6 The catalysts which may be preparecl using the presently contemplated hydrosols may con~ain crys~alline aluminosilicates such as type Y zeolite, or modified forms of type X and type Y zeoli.te which may be thermally treated and ex~changed with rare earth ions as disclosed in V.S. 3,~02,996, 3,607,0~3, or 3,676,368. Furthermore, the zeolite may be thermally s-tabilized as shown in U.S. 3,293,192 or 3,~49,070. The catalysts in addition to zeolite may contain weighting agents such as clay which may be kaolin, metakaolin, or halloysite. Further-more, the weighting agent may include inorganic oxides such as alumina, and silica-alumlna.
The catal~sts prepared by the process disclosed herein are particularly useful for the processing .-or converting of petroleum hydrocarbons. Typically, these catalytic cracking catalyts are used in fluid or fixed bed cracking processes wherein a hydrocarbon feedstock is contacted with the~catalyst :
at a temperature of from about 700 to 1000F. Further~
more the presently contemplated titania-alumina-silica hydrosol binders find application in the preparation of other hydrocar.bon.conversion catalysts such as hydro-cracking catalyts, isomerization catalysts, and reforming catalysts as well as auto exhaust oxidation.catalysts. The hydrosol binders may be combined with alumina to form extrudates, beads, and pills that may be used as supports for a variety of catalysts. It is also contemplated that the hydrosols may be spray dried to form hard attrition resistant composites o~ titania-alumina-silica possessing ion exchange capability.

~3~6 A typical process which may be utilized to prepare the hydrosols in catalysts of the present inven-tion is set forth in the drawing. Reference to the drawiny reveals that the source of titanium salt solution which typically has a concentration of from about 1% to 10~ by weight Tio2 in wa-ter is connected to a mixed salt tank.
Also connec-ted to bhe mixed salt tank i6 a source of aluminum salt solution which has a concentration of from about 1 to 8 A12O3 % by weiyht in water. The mixed salt tank is connected to a mixing pump. A source of alkaii metal silicate solution is also connected to the mixing pump. The alkali metal silicate solution typically has a concentration of ~rom about 5 to 20% by weight alkaline metal silicate in water. The mixed titanium and aluminum salt solution, and alkaline metal silicate solution are metered to the mixing pump I in amounts which provide the desired ratios of E~2O, TiO2, and A12O3 to SiO2 indica~ed above. The pH of the hydrosol is maintained I at closely regulated levels of from about 2.5 to 3.5. In ¦ 20 general it is found that the mixed titania aluminum salt solution will possess a pH of about 0.7 to 2.2 and the alkall metal silicate solution will have an initial pH of from about 11.3 to 12Ø In general it is preferred to maintain the hydrosol at a temperature of from about 60 to 75E'. prior to use. It is found that the hydrosol is relatively stable at these temperatures and may be held for a period of from about 1/4 to 1 hour prior to utilization.

In the embodiment shown in the clrawing the hydrosol is prepared ln -the mixing pump and then conducted to the mixer, preferably a hiyh shear mixer. ~lso connected to the mlxer are sources of clay s:Lurry and zeolite slurry.
The clay slurry will typically comprise kaolin slurried in water in amounts where from abou-t 25 to 35% by weight kaolin is contained in the slurry. The zeoLite slurry will typically contain from about 20 to 30 weight percent zeolite mixed in water. The zeolite may be slurry p~l adjusted to p~I = 3.8 - 4.5 with minerai acid. In the process shown in the drawing the clay and zeolite slurries are metered into the mixer along with a hydrosol feed stream from the mixing pump. The hydrosol, clay and zeolite are continuously mixed in the mixer and then fed,to a spray '~
drier wherein the hydrosol-clay-zeolite slurry is dried.
Typically the spray drier is operated at an inlet gas temperature of from about 600 to 90-0F. and the gas outlet temperature of from about 300 to 400F. The spray dried catalyst product will typically possess a particle size -range of from about 20 to 300 microns. Subsequent to spray drying the catalyst composite is washed with water to remove soluble salts and may subsequently be ~chanyed with catalytically active or stabilizing ions such as rare earth.
The catalyst composites prepared by way of the present invention are found to posse'ss a tough uniform homogeneous structure which is particularly attrition resistant. Furthermore, the catalyst composites wi~l possess a surface area of from about 150 to 225 m /g and a water pore volume of from about 0.20 to 0.30 cc/g.

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and a nitroc~en pore volume o:E 0.0~ to 0.15 cc/g.
I-laving described the basic aspects o:E the present inven~ion the followiny examples are yiven to illustrate the speclfic embodiments thereof.
In the examples the Davison Att.ri-tion Index (D.I.) was determined as follows:
A 7 g. sample is screened to remove particles.in the 0 to 20 micron size range. The particles above 20 microns are then subjected to a 5 hour test in the standard ~oller Particle Size Analyzer usiny a 0.07 .inch jet and 1 inch I.D. U-Tube as supplied by American Instrument Company, Silver Spring, Maryland.
An air flow of 21 liters per minute is used. The Davison Index is calculated as follows:

Davison 0 - 20 micron material formed during test Index Original 20 ~ micron fraction X 100 The catalysts-were evaluated by comparing the activity of these catalysts with the activity of a standard catalyst containing rare earth faujasite. In this 20 comparison both catalysts are subjected to the standard -activity test described.by Ciapetta and ~enderson in the Oil and Gas Journal of October 16, 1967 at payes 88 to 93.

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. - 8 -_xample I
Using a sys-tem similar to that shown in the drawing, 19.49 lbs.-of mixed titanium sulfate-aluminum sulfate mixed salt solution con-taining as oxides 3.85 W-t.
percent Tio2 and 3.89 Wt. percent Al2O3 was continuously introduced to mixing pump l. Simultaneously, 80.51 lbs. of sodium silicate of 18Be gravity and 3.36 SiO2/Na2O
ratio was continuously introduced to mixing pump. The two flowing streams reacted in the mixing pump and a hydrosol of 3.05 pM was continuously produced and collected.
One hundred pounds of hydrosol was transferred to a high speed mixer. While the hydrosol was being stirred, 32.6 lbs. of dry commercial KCS clay and 8.9 lbs. (dry basis) synthetiG Na-Y fau]asite as an aqueous slurry of 4.0 pH containing 33 percent solids were added.
The composite mixed aqueous slurry of titania-alumina-silica hydrosol, KCS clay and synthetic Y faujasite was pumped to a commercial spray dryer having a rotating ~¦ 20 dispersing vane which rotated at 11,850 rpm and was dried at a dryer gas inlet temperature of 625F. and a gas outlet temperature of 350F. The spray dried material was '~ : washed with hot water to remove the sodium sulfate, exchanged with rare earth chloride so]ution, water washed and dried. The resulting catalyst had the pr~perties set forth in the Table.

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~xamp e Il In a manner similar to Example I, 21.~ lhs.
of mixed titanium sulfate~aluminum sulfa-te mixed sal-t solution containing as oxldes 3.85 Wt. % TiO2 and 3.89 ~t.
A12O3 was continuously reacted with 78.56 lbs. of sodium sillcate of 20Be gravity and 3.36 SiO2/Na2O
ratio in the mixing pump to form a hydrosol of 3~05 plI.
One hundred lbs. of mixed hydrosol was transferred to a high speed mixer. While the hydrosol was beiny 10 stirred, 35.6 lbs. of dry commercial KCS kaolin clay and 9.7 lbs. (dry basis) synthetic Na-Y faujasite as an aqueous slurry of 4.0 pll containing 35 Wt. ~ solids were added.
The composite mix of hydrosol, YCS clay and synthetic Y faujasite was pumped to a commercial spray drier and dried at a dryer gas inlet-of 625F and a gas outle-t - temperature of 350F. The spray dried material was washed with hot water to rèmove the sodium sulfate, exchanged with rare earth chloride solution, water washed and dried.
The properties of the catalyst are set forth in the Table.

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~xample I _ II
Total Volatiles % by Wt. 10.11 10.53 A12O3, Wt. % (dry basis) 33.80 33.85 Re2O3, Wt. ~ (dry basis) 3.20 3.42 Na2O, Wt. % (dry basis) 0.55 0.39 SOa, Wt. % (dry basis) 0.11 0.03 TiO2, Wt. % (dry basis) 2.97 2.98 Surface Area (m2/g) 179 168 Pore Volume (N) 0.12 0.11 Pore Diameter ' 26 26 Pore Volume (H2O) 0.24 0.24 D.I. 3 5 J.I. 0.1 0.7 Average Bulk Density (cc/g) 0.77 0.79 Average Particle Size(microns) 60 78 Microactivity after steaming at 1350F.
Sample, % conversion 81.2 81.5 Standard, % conversion 75.0 75.0 Binder Wt. % A123 6.5 6.8 Wt. % TiO2 6.5 6.8 Wt. ~ SiO2 87.0 86.4 Catalyst Wt. ~ Binder 24.8 24.0 Wt. %-Clay 58.8 57.6 Wt. % Na-Y 2eolite 16.4 18.4 After 1 Hour @ 1500F Thermal Pretreat of Sample _ D.I. 2 ` 6 J.I. - 0-9 0.2 Average Bulk Density (g/cc) 0.83 0.84 Peak Height ~ . .
1000F. 56 57 1600F. ~ 50 51 Microactivity @ 1350F.
Sample, ~j conversion 77 9 78.6 Standard, ~i conversioll 69.9 69.9 ., ~

' i, ' EX ~lllp 1~ :[II
A sc~mple of spray dried hydrosol was prepared -~as follows:
23.0 lbs. of mixed tit~nium sulfate-aluminum sulfate solution con-taining as oxides 2.81 W-t percent TiO2 and 3.75 Wt. percent A12O3 was con-tinuously reacted wi-th 83.15 lbs. of sodium silicate of 18Be gravity and 3.36 SiO2/Na2O ratio in a mixing pump to form a hvdrosol of 3.0 pII.
The 106.15 lbs. of mixed hydrosol was pumped to a commercial spray dryer and dried at a dryer gas inlet of 625F. and a gas outlet temperature of 350F. The spray dried material was washed with hot water to remove sodium sulfate and drled. The dried titania-alumina-silica compound had the following chemical analysis and physical properties:
Tio2 Weight % (dry basis) = 7.17% Bulk Density - 0.58 g/cc `A12O3 Weight % (dry basis) = 9.62% Surface Area = 200 m2/g SiO2 Welght % (dry basis) = 82.15% P.V. (H2O) = 0.22 cc/g Na2O Weight % (dry basis) = 0.31% - P.V. (N2) = 0.11 cc/g - SO~ Weight % (dry basis) = 0.75%
Example IV
In a manner similar to Example III, 68.3 lbs. of mixed titanium sulfate-aluminum sulfate solutions containing - as oxides 1.29 W-t. pércent TiO2 c~nd 1.32 Wt. percent A120 was continuously reacted with 74 lbs. of sodium silicate ! of l6.5Be gravity and 3.36 SiO2/Na2O ratio in the mixing pump to form a hydrosol of 3,15-pH.

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The 142.3 pounds of mixed hydrospl was pumped -to a commercial spray dryer and dried at a dryer gas in].et of 600F. and a yas outlet temperature of 350F. The spray dried material was washed with hot water to remove sodium sulfate, exchanged with xare ear-th chloride solution, water washed and dried.
The product had a surEace area of 220 m2/y, contained 5.84 Wt. percent (D.B.) Re2O3 and had a catalytic ac-tivity of 14.4 percent conversion compared to a standard catalyst activity of 71.4 percent conversion.
This behavior indica-tes the dried matrix possesses some catalytic activity as well as cation exchanyeability.
The above examples clearly indicate that the hydrosols of the present invention may be used to prepare valuable cracking catalyst compositions.
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Claims (12)

I CLAIM:

1. A titania-alumina-silica hydrosol which comprises the following amounts by weight TiO2, Al2O3, SiO2 and H2O:
(a) 0.01 to 0.12 parts TiO2 per part SiO2, (b) 0.01 to 0.15 parts Al2O3 per part SiO2, and (c) 6 to 25 parts H2O per part SiO2, said hydrosol having a pH of from about 2.5 to 3.5.

2. The hydrosol of Claim 1 wherein said TiO2 is derived from soluble titanium sulfate and said Al2O3 is derived from aluminum sulfate.

3. The hydrosol of Claim 1 which is obtained by combining an aqueous solution of a titanium salt and an aluminum salt with a solution of alkali metal silicate.

4. The hydrosol of Claim 3 wherein said alkali metal silicate is sodium silicate.

5. A particulate titania-alumina-silica dried product having the composition expressed as percent by weight SiO2, TiO2 and Al2O3 as follows:
(a) SiO2 - 78 to 98, (b) TiO2 - 1 to 10, and (c) Al2O3 - 1 to 12.

6. A process for preparing hydrocarbon conversion catalysts which comprises:
(a) preparing an aqueous slurry of a crystalline aluminosilicate zeolite and a titania-alumina-silica hydrosol binder, said hydrosol binder comprising the following amounts by weight TiO2, Al2O3, SiO2 and H2O
(1) 0.01 to 0.12 parts TiO2 per par-t SiO2, (2) 0.01 to 0.15 parts Al2O3 per part SiO2, and (3) 6 to 25 parts H2O per part SiO2 said hydrosol having a pH of from about 2.8 to 3.2; and (b) spray drying said slurry to form discrete catalyst particles.

7. The process of Claim 6 wherein said slurry has a pH of about 3.0 to 3.9 prior to drying.

8. The process of Claim 7 wherein the slurry is maintained at a temperature of from about 65 to 75°F prior to drying.

9. The process of Claim 8 wherein said slurry is spray dried to obtain a catalyst having a particle size of from about 20 to 300 microns.

10. The process of Claim 9 wherein said catalyst is washed to remove soluble impurities.

11. The process of Claim 10 wherein said catalyst is exchanged with a solution of rare earth cations.

12. The process of Claim 6 wherein said zeolite is a type Y zeolite having a silica to alumina ratio of about 3.5 to 5.5.