Description:FIELD
The present disclosure relates to a process for the preparation of an attrition resistant high pore volume silica-alumina materials.
DEFINITIONS
As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used indicate otherwise.
Attrition index: The term “attrition index” refers to the amount of fines formed from silica-alumina material / catalysts due to physical abrasion, attrition, and/ or grinding of particles during its use in the catalytic conversion processes or testing units. Lower attrition index of <10 means, the material has high attrition resistant. Attrition index of a catalysts /material is measured by ASTM D5757 / Jet cup method.
Sol: The term “sol” refers to a liquid state of a colloidal solution.
Gel: The term “gel” refers to a solid or semi-solid state of a colloidal solution.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
The silica-alumina materials (SAM) are used as a support and a catalyst material in refining and chemical industry. Silica-alumina materials with desirable high pore volume, large surface area and pore diameter are the important characteristics of the materials. Additionally, SAM are relatively stable materials and have an adjustable shape and porosity. While their Bronsted acid sites and catalytic activity are undoubtedly lower than those of zeolites, their coking tendency is also lower, making them preferable for some special applications. Additionally, these materials exhibit tuneable characteristics for metal and cationic centres, making them extremely important and versatile catalytic supports. Due to the surface acid sites and localized structure, silica-alumina materials with a large pore volume find applications in industrially significant processes. High pore volume materials can accommodate higher amount of active metal components, and this prompts application for catalytic gasification of coal and biomass.
In the known process, sodium-containing silica sources were used to make high pore volume silica-alumina materials. The known processes utilize expensive organic aluminium and silica sources as their metal alkoxides. Their synthesis is complicated by the presence of sodium and the high cost of organic silica and alumina sources. Furthermore, removing the salt that is present in the silica-alumina mixture is a challenging process.
Attrition index, particle size, and bulk density of silica-alumina materials are the important characteristics for application in fluidized catalytic processes for coal and biomass gasification. Hence, the preparation of silica-alumina materials with aforementioned properties for various industrial catalytic application is desirable.
There is, therefore, felt a need to provide a process for making attrition resistant high pore volume silica-alumina materials that mitigates the aforementioned drawbacks or at least provide an alternative solution.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.
An object of the present disclosure is to ameliorate one or more problems of the background or to at least provide a useful alternative.
Another object of the present disclosure is to provide a process for the preparation of attrition resistant high pore volume silica-alumina material.
Still another object of the present disclosure is to provide high pore volume silica-alumina precursors by using sodium free silica and alumina sources by hydrothermal treatment of silica and alumina gel or sol.
Yet another object of the present disclosure is to provide a process for the preparation of attrition resistant high pore volume silica-alumina material that are simple, sustainable, and economical.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure relates to a process for the preparation of attrition resistant high pore volume silica-alumina material. In embodiment of the present disclosure, the process for preparation of attrition resistant high pore volume silica-alumina materials comprises preparation of high pore volume silica-alumina precursor by acidifying colloidal silica particles by using an acid to obtain an acidified silica having a predetermined pH. An aluminium precursor solution is separately prepared by dissolving an aluminium precursor in water under stirring at a temperature in the range of 20 oC to 40 oC. The obtained aluminium precursor solution is added to the acidified silica under stirring to obtain a silica-alumina sol. At least one base is added to the silica-alumina sol to attain a pH in the range of 7 to 8 to obtain a gel. The obtained gel is hydrothermally heated in an autoclave at a first predetermined temperature for a first predetermined time period to obtain a heated gel. The heated gel is cooled to a temperature in the range of 25oC to 40 oC followed by filtering to obtain solids and washing the solids with an aqueous ammonia solution having a pH in the range of 7 to 9 to obtain a wet cake of the high pore volume silica-alumina precursor. The wet cake is optionally dried at a second predetermined temperature for a second predetermined time period followed by calcining at a third predetermined temperature for a third predetermined time period to obtain the high pore volume silica-alumina precursor. Further, the wet cake of the high pore volume silica-alumina precursor or the high pore volume silica-alumina precursor is mixed with at least one binder, at least one stabilizer and water at a temperature in the range of 25 oC to 40 oC to obtain a slurry. The slurry is spray dried at a fourth predetermined temperature for a fourth predetermined time period to obtain a spray dried material in the form of microspheres. The obtained spray dried material is calcined at a fifth predetermined temperature for a fifth predetermined time period with a predetermined ramp rate to obtain the attrition resistant high pore volume silica-alumina material.
In accordance with the embodiments of the present disclosure, the acid is at least one selected from the group consisting of nitric acid, sulfuric acid, formic acid, and acetic acid.
In accordance with the embodiments of the present disclosure, the acid is a concentrated acid having a concentration of 65% and above.
In accordance with the embodiments of the present disclosure, the predetermined pH of acidified silica is in the range of 2.5 to 4.
In accordance with the embodiments of the present disclosure, the colloidal silica is a sodium free silica. In an embodiment of the present disclosure, the colloidal silica has a particle size in the range of 10 nm to 20 nm.
In accordance with the embodiments of the present disclosure, the aluminium precursor is at least one selected from the group consisting of aluminium nitrate, aluminium sulfate, aluminium acetate, aluminium formate, aluminium chloride, aluminium oxide, aluminium oxyhydroxide, and aluminium trihydroxides.
In accordance with the embodiments of the present disclosure, a non-ionic surfactant is added to the gel before hydrothermal heating. The non-ionic surfactant is block copolymer of polyethylene glycol and polypropylene glycol (Pluronic P123).
In accordance with the embodiments of the present disclosure, the base is selected from the group consisting of an aqueous ammonia solution, and organic amines.
In accordance with the embodiments of the present disclosure, the first predetermined temperature is in the range of 150oC to 200 oC.
In accordance with the embodiments of the present disclosure, the first predetermined time period is in the range of 20 hours to 30 hours.
In accordance with the embodiments of the present disclosure, the second predetermined temperature is in the range of 100 oC to 150 oC.
In accordance with the embodiments of the present disclosure, the second predetermined time period is in the range of 6 hours to 24 hours.
In accordance with the embodiments of the present disclosure, the third predetermined temperature is in the range of 500 oC to 700 oC.
In accordance with the embodiments of the present disclosure, the third predetermined time period is in the range of 1 hour to 5 hours.
In accordance with the embodiments of the present disclosure, the binder is selected from the group consisting of a reactive colloidal silica, and psuedoboehmite alumina.
In accordance with the embodiments of the present disclosure, the stabilizer is selected from the group consisting of urea, ammonium carbonate, ammonium bicarbonate, sodium hexametaphosphate, polycarboxylate ether, citric acid, oxalic acid, ammonium salt of polyacrylic acid, polydiallydimethylammonium chlorides, hexamethylene tetraamine (HMTA), ethylene diamine tetra-acetic acid (EDTA), polyacrylamide and their derivatives.
In accordance with the embodiments of the present disclosure, the surfactant is selected from octylphenol ethylene oxide condensate, cetrytrimethylammonium bromide, block copolymer of polyethylene glycol and polypropylene glycol (pluronic P123 block copolymer), and octylphenol ethoxylate.
In accordance with the embodiments of the present disclosure, the slurry has a solid content in the range of 10 mass% to 30 mass%, and the slurry has water content in the range of 70 mass% to 90 mass%.
In accordance with the embodiments of the present disclosure, the fourth predetermined temperature is in the range of 150oC to 450oC; and the fourth predetermined time period is in the range of 15 minutes to 60 minutes.
In accordance with the embodiments of the present disclosure, the spray drying is done by using a spray dryer having an inlet temperature in the range of 350 oC to 450 oC and an outlet temperature in the range of 150 oC to 200 oC.
In accordance with the embodiments of the present disclosure, the fifth predetermined temperature is in the range of 500oC to 700 oC, and the fifth predetermined time period is in the range of 1 hour to 5 hours.
In accordance with the embodiments of the present disclosure, the predetermined ramp rate is in the range of 1oC/min to 5 oC/min.
The present disclosure further provides an attrition resistant high pore volume silica-alumina material, characterized by having an attrition index less than 10%; a pore volume greater than 0.7 cc/g; and a specific surface area in the range of 100 m2/g to 400 m2/g.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING

The present disclosure will now be described with the help of the accompanying drawing, in which:
Figure 1 illustrates a process flow diagram for the process of preparation of high pore volume silica-alumina material by spray-drying in accordance with the present disclosure; and
Figure 2 illustrates a process flow diagram of preparation of high pore volume silica-alumina precursor by hydrothermal treatment in accordance with the present disclosure.
DETAILED DESCRIPTION
The present disclosure relates to a process for the preparation of an attrition resistant high pore volume silica-alumina material.
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details, are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed elements.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
The silica-alumina materials (SAM) are used as support and catalyst materials in refining and chemical industry. Silica-alumina materials with desirable high pore volume, large surface area and pore diameter are the important characteristics of the materials.
Manufacturing of silica-alumina materials is a known process, which utilizes expensive organic aluminium and silica sources as their metal alkoxides. Their synthesis is complicated by the presence of sodium and the high cost of organic silica and alumina sources. Furthermore, removing the salt that is present in the silica-alumina mixture is a challenging process.
Attrition index, particle size, and bulk density of silica-alumina materials are the important characteristics for application in fluidized catalytic processes for coal and biomass gasification. Hence, the preparation of silica-alumina materials with aforementioned properties for various industrial catalytic application is desirable.
The present disclosure relates to a process for the preparation of an attrition resistant high pore volume silica-alumina material.
The process for preparation of attrition resistant high pore volume silica-alumina materials comprises the following steps:
In a first step, high pore volume silica-alumina precursor is prepared by acidifying colloidal silica particles by using an acid to obtain an acidified silica having a predetermined pH.
In an exemplary embodiment of the present disclosure, the colloidal silica is a sodium free silica. The particle size of the colloidal silica is in the range of 10 nm to 20 nm.
Colloidal silica is the dispersed phase of silica nanoparticles in an aqueous ammonia solution having the pH range of 8 to 10 and silica particles present in the form of polymeric chain. When acidified, it converts into monomeric reactive silica particles. Higher particle size may affect the reactivity of the acidified silica and the surface properties of final product. Sodium-free silica makes the process viable and minimize the cumbersome washing to remove sodium ion from the highly viscous gel material, when used sodium containing silica. It is known that the presence of sodium ions poisons the acid sites in silica-alumina material which affects the catalytic activity. It may be noted that, when sodium silicate is used as a silica source, the pore volume of the silica-alumina material is found to be smaller than that using sodium free silica under similar reaction conditions.
In accordance with the embodiments of the present disclosure, the colloidal silica has a silica content in the range of 10% to 40%. In another embodiment of the present disclosure, the colloidal silica has a silica content in the range of 25% to 35%. In an exemplary embodiment, the colloidal silica has a silica content of 30%. The colloidal silica is stabilized by using the aqueous ammonia solution.
In accordance with the embodiments of the present disclosure, the acid is at least one selected from the group consisting of nitric acid, sulfuric acid, formic acid and acetic acid. In an exemplary embodiment, the acid is nitric acid. In another exemplary embodiment, the acid is sulfuric acid.
In accordance with the embodiments of the present disclosure, the acid is a concentrated acid having a concentration of 65% and above. In an exemplary embodiment, the acid has a concentration of 65%. In another exemplary embodiment, the acid has a concentration of 95%.
In accordance with the embodiments of the present disclosure, the predetermined pH of the acidified silica is in the range of 2.5 to 4. In an exemplary embodiment, the predetermined pH of the acidified silica is 3.5.
Separately, an aluminium precursor solution is prepared by dissolving an aluminium precursor in water under stirring at a temperature in the range of 20 oC to 40 oC. In an exemplary embodiment, the temperature of preparing aluminium precursor solution is 25 oC.
In accordance with the embodiments of the present disclosure, the aluminium precursor is at least one selected from the group consisting of aluminium nitrate, aluminium sulfate, aluminium acetate, aluminium formate, aluminium chloride, aluminium oxide, aluminium oxyhydroxide, and aluminium trihydroxide. In an exemplary embodiment, the aluminium precursor is aluminium nitrate. In another exemplary embodiment, the aluminium precursor is aluminium sulfate.
In accordance with the embodiments of the present disclosure, the aluminium precursor is present in an amount in the range of 20 mass% to 50 mass% with respect to the total amount of the aluminium precursor solution. In an embodiment, the aluminium precursor is present in an amount of 30 mass% with respect to the total amount of the aluminium precursor solution. In an exemplary embodiment, the aluminium precursor is present in an amount of 43% with respect to the total amount of the aluminium precursor solution. In the embodiment, water is present in an amount in the range of 50 mass% to 80 mass% with respect to the total amount of the aluminium precursor solution.
The obtained aluminium precursor solution is added to the acidified silica under stirring to obtain a silica-alumina sol. The so obtained silica-alumina sol has a very low pH i.e., in the range of 2 to 4 and is highly acidic in nature in which reactive monomeric silica species is present along with dissolved aqueous aluminium precursor.
The silica alumina ratio (SiO2:Al2O3 of 95:5, 80:20, 70:30, 60:40, 40:60, 30:70, 20:80, 5:95) in the silica alumina precursor is varied by adding the aluminium precursor solution and the acidified silica in a stoichiometric amount.
At least one base is added to the silica-alumina sol to attain a pH in the range of 7 to 8 to obtain a gel. The so obtained gel is a precipitate of silica-alumina formed by acid-base reaction. The gel will not be formed from silica-alumina sol in the absence of a base. So, the base is added to the silica-alumina sol to attain a pH in the range of 7 to 8 to obtain a gel.
In accordance with the embodiments, the non-ionic surfactant is added to the gel before hydrothermal heating. In an exemplary embodiment, the non-ionic surfactant is 1 wt% pluronic P123. The addition of non-ionic surfactant to the gel before hydrothermal heating improves the total pore volume and pore diameter of the silica alumina precursor.
In accordance with the embodiments of the present disclosure, the base is selected from the group consisting of an aqueous ammonia solution, and organic amines. In an exemplary embodiment, the base is 25% aqueous ammonia solution.
The so obtained gel is hydrothermally heated in an autoclave at a first predetermined temperature for a first predetermined time period to obtain a heated gel. The hydrothermal temperature can also be referred as aging temperature in the present disclosure.
In accordance with the embodiments of the present disclosure, the first predetermined temperature is in the range of 150 oC to 200 oC. In another exemplary embodiment, the first predetermined temperature is 175 oC. The temperature below 150 oC requires comparatively more time as illustrated in Examples 1 to 3. The temperature above 200 oC will not provide desired properties of the catalyst.
In accordance with the embodiments of the present disclosure, the first predetermined time period is in the range of 20 hours to 30 hours. In an exemplary embodiment, the first predetermined time period is 24 hours.
The heated gel is cooled to a temperature in the range of 25oC to 40 oC followed by filtering to obtain solids and washing the solids with an aqueous ammonia solution having a pH in the range of 7 to 9 to obtain a wet cake of the high pore volume silica-alumina precursor.
The wet cake is optionally dried at a second predetermined temperature for a second predetermined time period followed by calcining at a third predetermined temperature for a third predetermined time period to obtain the high pore volume silica-alumina precursor.
In accordance with the embodiments of the present disclosure, the second predetermined temperature is in the range of 100 oC to 150 oC. In an exemplary embodiment, the second predetermined temperature is 120 oC.
In accordance with the embodiments of the present disclosure, the second predetermined time period is in the range of 6 hours to 24 hours. In an exemplary embodiment, the second predetermined time period is 12 hours.
In accordance with the embodiments of the present disclosure, the third predetermined temperature is in the range of 500 oC to 700 oC. In an exemplary embodiment, the third predetermined temperature is 600 oC.
In accordance with the embodiments of the present disclosure, the third predetermined time period is in the range of 1 hour to 5 hours. In an exemplary embodiment, the third predetermined time period is 3 hours.
The step of filtration and washing of the solids of silica-alumina precursor is performed to remove the sulfate and/or nitrate from ammonium precursors, and to remove excess of ammonia.
In a second step, the wet cake of the high pore volume silica-alumina precursor or the high pore volume (HVP) silica-alumina precursor is mixed with at least one binder, at least one stabilizer and water at a temperature in the range of 25 oC to 40 oC to obtain a slurry.
In accordance with the embodiments of the present disclosure, the binder is selected from the group consisting of a reactive colloidal silica and psuedoboehmite alumina. In an exemplary embodiment, the binder is the reactive colloidal silica.
In accordance with the embodiments of the present disclosure, the stabilizer is selected from the group consisting of urea, ammonium carbonate, ammonium bicarbonate, sodium hexametaphosphate, surfactants, polycarboxylate ether, citric acid, oxalic acid, ammonium salt of polyacrylic acid, polydiallydimethylammonium chlorides, hexamethylene tetraamine (HMTA), ethylene diamine tetra-acetic acid (EDTA), polyacrylamide and their derivatives. In an exemplary embodiment, the stabilizer is urea. In another embodiment of the present disclosure, the surfactant is selected from octylphenol ethylene oxide condensate, cetrytrimethylammonium bromide, block copolymer of polyethylene glycol and polypropylene glycol (pluronic P123 block copolymer), and octylphenol ethoxylate. In an exemplary embodiment, the surfactant is octylphenol ethylene oxide condensate (Triton X-100).
In accordance with the embodiments of the present disclosure, the binder is present in an amount in the range of 5 mass% to 45 mass% with respect to the total amount of the slurry; and the stabilizer is present in an amount in the range of 0.5 mass% to 5 mass% with respect to the total amount of the slurry. In an exemplary embodiment, the binder is present in an amount of 30 mass% with respect to the total amount of slurry; and the stabilizer is present in an amount of 1 mass% with respect to the total amount of the slurry.
In accordance with the embodiments of the present disclosure, the slurry has a solid content in the range of 10 mass% to 30 mass%; and the slurry has water content in the range of 70 mass% to 90 mass%. In an exemplary embodiment, the slurry has a solid content of 13%.
In a third step, the slurry is spray dried at a fourth predetermined temperature for a fourth predetermined time period to obtain a spray dried material in the form of microspheres.
In accordance with the embodiments of the present disclosure, the fourth predetermined temperature of the spray drier is in the range of 150 oC to 450 oC. In an exemplary embodiment, the fourth predetermined temperature is 180 oC. In an exemplary embodiment, the fourth predetermined temperature is 400 oC. In accordance with the embodiments of the present disclosure, the spray drying is done by using a spray dryer having an inlet temperature in the range of 350oC to 450oC and an outlet temperature is in the range of 150oC to 200oC. In an exemplary embodiment, the spray dryer is having the inlet temperature of 400oC and the outlet temperature of 180 oC.
In accordance with the embodiments of the present disclosure, the fourth predetermined time period is in the range of 15 minutes to 60 minutes. In an exemplary embodiment, the fourth predetermined time period is 25 minutes.
The stabilizers help to stabilize the slurry that helps to obtain the spray dried material with uniform shape and high strength.
In a final step, the spray dried material is calcined at a fifth predetermined temperature for a fifth predetermined time period with a predetermined ramp rate to obtain the attrition resistant high pore volume silica-alumina material.
In accordance with the embodiments of the present disclosure, the fifth predetermined temperature is in the range of 500 oC to 700 oC. In an exemplary embodiment, the fifth predetermined temperature is 600 oC.
In accordance with the embodiments of the present disclosure, the fifth predetermined time period is in the range of 1 hour to 5 hours. In an exemplary embodiment, the fifth predetermined time period is 3 hours.
In accordance with the embodiments of the present disclosure, the predetermined ramp rate is in the range of 1oC/min to 5 oC/min. In an exemplary embodiment, the predetermined ramp rate is 2oC/min.
In accordance with the embodiments of the present disclosure, the attrition resistant high pore volume silica-alumina material is characterized by having an attrition index less than 10%, a pore volume greater than 0.7 cc/g, and a specific surface area in the range of 100 to 400 m2/g. In an exemplary embodiment, the attrition resistant high pore volume silica-alumina material has the attrition index of 9 and the pore volume of 0.74 cc/g. In another exemplary embodiment, the attrition resistant high pore volume silica-alumina material has the attrition index of 7, and the pore volume of 0.70 cc/g.
The conventional processes require two steps of spray drying, one before hydrothermal heating and another after adding the binder and stabilizer to the alumina-silica precursor. The process of the present disclosure does not require a step of drying or spray drying before the hydrothermal heating.
The present disclosure provides to a process for the preparation of attrition resistant high pore volume silica-alumina materials. For the application of the silica-alumina material in fluidized catalytic processes for coal and biomass gasification, the properties of silica-alumina material such as attrition index, particle size, and bulk density are the important. Further, the attrition resistant high pore volume silica-alumina material can be used as a catalyst and a sorbent material for various industrial catalytic processes such as for the catalytic gasification/ co-gasification of biomass, pet coke and coal; as a bottom cracking additive/ catalyst components in the fluid catalytic cracking process; as a support material / sorbent for CO2 capture process; as a support material for metal impregnation for hydrocracking, hydro-treatment, hydro-isomerization, hydrogenation and dehydrogenation; and for the catalytic pyrolysis processes. The process of the present disclosure employs conventional raw materials which are cost-effective and environment-friendly. The process of the present disclosure does not utilize any organic source of silica and/or alumina.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.
EXPERIMENTAL DETAILS
Example 1: Process for the preparation of high pore volume silica-alumina precursor
Concentrated nitric acid (above 65%) was added dropwise into 267 g of sodium free colloidal silica (30% silica, pH 9.3) to form an acidified silica with desired pH value of 3.5. Separately, 150.1 g of aluminium nitrate was added into 200 ml of demineralized water at 25 oC to form an aqueous solution of aluminium nitrate (~3.5 M). The aqueous solution of aluminium nitrate was completely mixed to minimize any unwanted gel or particle formation. The obtained aqueous solution of aluminium nitrate was mixed with the acidified silica under stirring to obtain a silica-alumina sol. Then, 95 to100 ml of an aqueous ammonia solution (25%) was added into the silica-alumina sol to obtain a gel having pH of 7to 8. The gel had a solid content of approximately 13to 14%. This gel was transferred into 100 ml capacity Teflon-lined stainless-steel autoclave which was hydrothermally heated at 60°C temperature for 72 hours to obtain a heated gel. The autoclave containing the heated gel was allowed to cool to room temperature (27 oC) and the gel was filtered and washed with diluted ammonia water (pH, 7-9) to remove the soluble and residual salts and to obtain a wet cake. The wet cake was dried at 120°C for 12 hours and calcined at 600°C for 3 hours to obtain the high pore volume of silica alumina precursor having a silica to alumina ratio of 80:20 (refer Fig. 2 for the preparation of high pore volume silica-alumina precursor by hydrothermal treatment).
The calcined material showed a specific surface area of 263 m2/g, pore volume of 0.62 cc/g and an average pore diameter of 94 Å as shown in the Table 1.
Example 2: Process for the preparation of high pore volume silica-alumina precursor
Concentrated nitric acid (above 65%) was added dropwise into 267 g of sodium free colloidal silica (30% silica, pH 9.3) to form an acidified silica with desired pH value of 3.5. Separately, 150.1 g of aluminium nitrate was added into 200 ml of demineralized water at 25 oC to form an aqueous solution of aluminium nitrate. The obtained aqueous solution of aluminium nitrate was mixed with the acidified silica under stirring to obtain a silica-alumina sol. Then, 95to 100 ml of aqueous ammonia solution (25%) was added into the silica-alumina sol to obtain a gel having pH of 7to 8. The gel had a solid content of approximately 13 to14%. This gel was transferred into 100 ml capacity Teflon-lined stainless-steel autoclave which was hydrothermally heated at 120°C temperature for 24 hours to obtain a heated gel. The autoclave containing heated gel was allowed to cool to a room temperature (27 oC) and the gel was filtered and washed with diluted ammonia water (pH, 7-9) to remove the soluble and residual salts and to obtain a wet cake. The wet cake was dried at 120°C for 12 hours and calcined at 600°C for 3 hours to obtain the high pore volume of silica alumina precursor having silica to alumina ratio of 80:20.
The calcined material showed a specific surface area of 265°C m2/g, a pore volume of 0.67 cc/g and an average pore diameter of 101 ÅÅ as shown in the Table 1.
Example 3: Process for the preparation of high pore volume silica-alumina precursor
Concentrated nitric acid (above 65%) was added dropwise into 267 g of sodium free colloidal silica (30% silica, pH 9.3) to form an acidified silica with desired pH value of 3.5. Separately, 150.1 g of aluminium nitrate was added into 200 ml of a demineralized water at 25 oC to form an aqueous solution of aluminium nitrate. The obtained aqueous solution of aluminium nitrate was mixed with the acidified silica under stirring to obtain a silica-alumina sol. Then, 95 to 100 ml of an aqueous ammonia solution (25%) was added into the silica-alumina sol to obtain a gel having pH of 7 to 8. The gel had solid content of approximately 13% to 14%. This gel was transferred into 100 ml capacity Teflon-lined stainless-steel autoclave which was hydrothermally heated at 120°C for 72 hours to obtain a heated gel. The autoclave containing the heated gel was allowed to cool down to room temperature (27 oC) and the gel was filtered and washed with diluted ammonia water (pH, 7 to 9) to remove the soluble and residual salts to obtain a wet cake. The wet cake was dried at 120°C for 12 hours and calcined at 600°C for 3 hours to obtain the high pore volume of silica alumina precursor having silica to alumina ratio of 80:20.
The calcined material showed a specific surface area of 271 m2/g, a pore volume of 0.66 cc/g and a pore diameter of 97 Å as shown in the Table 1.
Example 4: Process for the preparation of high pore volume silica-alumina precursor in accordance with the present disclosure
Concentrated nitric acid (above 65%) was added dropwise into 267 g of soium free colloidal silica (30% silica, pH 9.3) to form acidified silica with desired pH value of 3.5. Separately, 150.1 g of aluminium nitrate was added into 200 ml of a demineralized water at 25 oC to form an aqueous solution of aluminium nitrate. The obtained aqueous solution of aluminium nitrate was mixed with the acidified silica under stirring to obtain a silica-alumina sol. Then, 95 to 100 ml of the aqueous ammonia solution (25%) was added into the silica-alumina sol to obtain a gel having pH of 7 to 8. The gel had a solid content of approximately 13% to 14%. This gel was transferred into 100 ml capacity Teflon-lined stainless-steel autoclave which was hydrothermally heated at 175°C temperature for 24 hours to obtain a heated gel. The autoclave containing the heated gel was allowed to cool to a room temperature (27 oC) and the gel was filtered and washed with diluted ammonia water (pH, 7-9) to remove the soluble and residual salts to obtain a wet cake. The wet cake was dried at 120°C for 12 hours and calcined at 600°C for 3 hours to obtain the high pore volume of silica alumina precursor having silica to alumina ratio of 80:20.
The calcined material showed a specific surface area of 237 m2/g, a pore volume of 1.22 cc/g and an average pore diameter of 207 Å as shown in the Table 1.
Example 5: Process for the preparation of high pore volume silica-alumina precursor in accordance with the present disclosure
Concentrated sulfuric acid (above 95%) was added dropwise into 267 g of colloidal silica (30% silica, pH 9.3) to form an acidified silica with desired pH value of 3.5. Separately, 126.1 g of aluminium sulfate was added into 200 ml of a demineralized water at 25 oC to form an aqueous solution of aluminium sulfate. The obtained aqueous solution of aluminium sulfate was mixed with acidified silica under stirring to obtain ~ 596 g of silica-alumina sol. Then, 85 to 90 ml of aqueous ammonia solution (25%) was added into the silica-alumina sol to obtain a gel having pH of 7 to 8. The gel had a solid content of approximately 14 to 15%. The silica-alumina gel was hydrothermally heated at 175°C temperature with for 24 hours to obtain a heated gel. This heated gel was cooled to room temperature (27 oC) and filtered and washed with a diluted ammonia water (pH, 7 to 9) to remove the soluble and residual salts to obtain a wet cake. The wet cake was dried at 120oC for 12 hours and calcined at 600oC for 3 hours to obtain the high pore volume silica-alumina precursor having silica to alumina ratio of 80:20.
The calcined material showed a specific surface area of 199 m2/g, pore volume of 1.08 cc/g and a pore diameter of 218 Å as shown in the Table 1.
Example 6: Process for the preparation of high pore volume silica-alumina precursor by using sodium silicate (Comparative example)
126.1 g aluminium sulfate was dissolved in 200 ml of demineralized water to obtain an aqueous aluminium sulfate solution. 140 ml 6N H2SO4 was prepared by adding 23 ml of concentrated H2SO4 (above 95%) into 117 ml of demineralized water. Sodium silicate solution (10% silica) was prepared by adding 271 g of liquid sodium silicate solution into a demineralized water to make up 800 ml solution.
200 ml of aqueous aluminium sulfate solution and 140 ml 6N H2SO4 were mixed together in a container. Then, 800 ml of sodium silicate solution were added slowly into the container. The final pH of this mixture was 3.2. The mixture was aged at a room temperature (27 oC) for 4 hours. Then, pH of the slurry was adjusted to 6.5 by adding 75 ml of 25% of aqueous NH3 solution. This slurry was hydrothermally heated in an autoclave at 175°C for 24 hours. After ageing, the slurry was filtered and washed 8 times with diluted ammonia water (pH, 7 to 9) to remove the impurities of sodium ions and soluble salts to obtain a wet cake. The silica-alumina wet cake contains 12% of solid content. The wet cake was dried at 120 oC for 12 hours and calcined at 600 oC for 3 hours to obtain the high pore volume silica-alumina precursor having silica to alumina ratio of 80:20.
The calcined material showed a specific surface area of 81 m2/g, a pore volume of 0.34 cc/g and a pore diameter of 170 Å as shown in the Table 1.
Table 1. Hydrothermal synthesis of high pore volume silica-alumina precursors: Effect of hydrothermal synthesis temperature (Aging temperature), precursors source, and aging time
Example No. Alumina source Silica source SiO2/
Al2O3 (%) Aging temperature$ (°C) Aging time# (h) Specific Surface area (m2/g) Total pore volume (cc/g) Average pore diameter
(Å)
1 Aluminium nitrate Colloidal silica 80/20 60 72 263 0.62 94
2 Aluminium nitrate Colloidal silica 80/20 120 24 265 0.67 101
3 Aluminium nitrate Colloidal silica 80/20 120 72 271 0.66 97
4 Aluminium nitrate Colloidal silica 80/20 175 24 237 1.22 207
5 Aluminium sulfate Colloidal silica 80/20 175 24 199 1.08 218
6## Aluminium sulfate Sodium silicate 80/20 175 24 81 0.34 170
*Surface area, pore volume and pore diameter of silica-alumina material was determined by N2 adsorption-desorption BET method; $ first predetermined temperature; #first predetermined time period; ##comparative example
Table 1 shows that silica-alumina precursors synthesized using aluminium nitrate, aluminium sulfate, colloidal silica, as their raw materials sources at the temperatures of 60°C, 120°C, and 175°C and time periods from 24 to 72 hours, respectively. Examples 4 and 5 suggested that 175 °C was the optimized hydrothermal temperature to obtain high pore volume silica-alumina precursors by using sodium free silica and aluminium precursor.
Example 7: Process for the preparation of high pore volume silica-alumina precursor in accordance with the present disclosure
Concentrated nitric acid (above 65%) was added dropwise into 267 g of silica free colloidal silica (30% silica, pH 9.3) to form an acidified silica with desired pH value of 3.5. Separately, 150.1 g of aluminium nitrate was added into 200 ml of demineralized water to form an aqueous solution of aluminium nitrate. The obtained aqueous solution of aluminium nitrate was mixed with the acidified silica under stirring to obtain a silica-alumina sol. Then, 95 to 100 ml of an aqueous ammonia solution (25%) was added into the silica-alumina sol to obtain a gel having pH of 7 to 8. The gel had a solid content of approximately 13 to 14%. This gel was transferred into 100 ml capacity Teflon-lined stainless-steel autoclave which was hydrothermally heated at 175°C temperature for 24 hours to obtain a heated gel. The autoclave containing the heated gel was allowed to cool to a room temperature (27 oC) and the gel was filtered and washed with diluted ammonia water (pH, 7 to 9) to remove the soluble and residual salts to obtain a wet cake. The wet cake was dried at 120°C for 12 hours and calcined at 600°C for 3 hours to obtain the high pore volume of silica alumina precursor having silica to alumina ratio of 70:30.
The calcined material showed a specific surface area of 290 m2/g, a pore volume of 1.05 cc/g and an average pore diameter of 160 Å as shown in the Table 2.
Example 8: Process for the preparation of high pore volume silica-alumina precursor in accordance with the present disclosure
Concentrated nitric acid (above 65%) was added dropwise into 267 g of silica free colloidal silica (30% silica, pH 9.3) to form an acidified silica with desired pH value of 3.5. Separately, aluminium nitrate (150.1 g) was added into 200 ml of demineralized water to form an aqueous solution of aluminium nitrate. The obtained aqueous solution of aluminium nitrate was mixed with the acidified silica under stirring to obtain a silica-alumina sol. Then, 95 to 100 ml of an aqueous ammonia solution (25%) was added into the silica-alumina sol to obtain a gel having pH of 7 to 8. The gel had a solid content of approximately 13 to14%. This gel was transferred into 100 ml capacity Teflon-lined stainless-steel autoclave which was hydrothermally heated at 175°C temperature for 24 hours to obtain a heated gel. The autoclave was allowed to cool to a room temperature (27 oC) and the gel was filtered and washed with a diluted ammonia water (pH, 7 to 9) to remove the soluble and residual salts to obtain a wet cake. The wet cake was dried at 120°C for 12 hours and calcined at 600°C for 3 hours to obtain the high pore volume of silica alumina precursor having silica to alumina ratio of 60:40.
The calcined material showed a specific surface area of 310 m2/g, a pore volume of 0.97 cc/g and an average pore diameter of 125 Å as shown in the Table 2.
Example 9: Process for the preparation of high pore volume silica-alumina precursor in accordance with the present disclosure
Concentrated nitric acid (above 65%) was added dropwise into the 267 g of sodium free colloidal silica (30% silica, pH 9.3) to form an acidified silica with desired pH value of 3.5. Separately, aluminium nitrate (150.1 g) was added into 200 ml of demineralized water at 25 oC to form aqueous solution of aluminium nitrate. The obtained aqueous solution of aluminium nitrate was mixed with the acidified silica under stirring to obtain a silica-alumina sol. Then, 95 to 100 ml of an aqueous ammonia solution (25%) was added into the silica-alumina sol to obtain a gel having pH of 7 to 8. The gel had a solid content of approximately 13% to 14%. This gel was transferred into 100 ml capacity Teflon-lined stainless-steel autoclave which was hydrothermally heated at 175°C temperature for 24 hours to obtain a heated gel. The autoclave was allowed to cool to a room temperature (27 oC) and the gel was filtered and washed with diluted ammonia water (pH, 7 to 9) to remove the soluble and residual salts to obtain a wet cake. The wet cake was dried at 120°C for 12 hours and calcined at 600°C for 3 hours to obtain the high pore volume of silica alumina precursor having silica to alumina ratio of 30:70.
The calcined material showed a specific surface area of 389 m2/g, a pore volume of 1.04 cc/g and an average pore diameter of 107 Å as shown in the Table 2.
Example 10: Process for the preparation of high pore volume silica-alumina precursor in accordance with the present disclosure
Concentrated nitric acid (above 65%) was added dropwise into 267 g of colloidal silica (30% silica, pH 9.3) to form an acidified silica with desired pH value of 3.5. Separately. 150.1 g of aluminium nitrate was added into 200 ml of a demineralized water at 25 oC to form an aqueous solution of aluminium nitrate. The obtained aqueous solution of aluminium nitrate was mixed with the acidified silica under stirring to obtain a silica-alumina sol. Then, 95 to 100 ml of an aqueous ammonia solution (25%) was added into the silica-alumina sol to get the final pH between 7 to 8. The addition of 1 wt% Pluronic P123 non-ionic surfactant (mol. wt. ~5800 g/mol) into the silica-alumina gel. The precipitated gel had a solid content of approximately 13 to 14%. This gel was transferred into 100 ml capacity Teflon-lined stainless-steel autoclave which was hydrothermally heated at 175°C temperature for 24 hours to obtain a heated gel. The autoclave was allowed to cool to a room temperature (27 oC) and the gel was filtered and washed with a diluted ammonia water (pH, 7 to 9) to remove the soluble and residual salts to obtain a wet cake. The wet cake was dried at 120°C for 12 hours and calcined at 600°C for 3 hours to the high pore volume of silica alumina precursor having silica to alumina ratio of 30:70.
The calcined silica-alumina material showed a specific surface area of 295 m2/g, a pore volume of 1.35 cc/g and an average pore diameter of 184 Å as shown in the Table 2. Addition of 1 wt. % P123 increased the pore volume.
Table 2. Hydrothermal synthesis of high pore volume silica-alumina precursors: Effect of silica and alumina ratio
Example No. Alumina source Silica source SiO2/
Al2O3 (%) Aging temp.** (°C) Aging time*** (h) Specific surface area (m2/g) Total pore volume (cc/g) Average pore diameter (Å)
4 Aluminium nitrate Colloidal silica 80/20 175 24 237 1.22 207
7 Aluminium nitrate Colloidal silica 70/30 175 24 290 1.05 160
8 Aluminium nitrate Colloidal silica 60/40 175 24 310 0.97 125
9 Aluminium nitrate Colloidal silica 30/70 175 24 389 1.04 107
10# Aluminium nitrate Colloidal silica 30/70 175 24 295 1.35 184
#Addition of 1 wt. % P123; **first predetermined temperature; ***first predetermined time period
The surface area, the pore volume and the average pore diameter of the silica-alumina precursor were determined by N2 adsorption-desorption BET method. The Table 2 showed that effect of silica and alumina ratio changed the pore volume marginally. Further, the high pore volume silica-alumina precursors can be prepared with varying silica-alumina ratios.
Example 11: Process for the preparation of attrition resistant high pore volume silica-alumina material (a comparative example)
2 kg of silica-alumina precursor (on dry basis) batch was prepared by spray-drying of high pore volume silica-alumina slurry. The slurry of high pore volume (HPV) silica-alumina precursor having silica/alumina ratio of 80/20 of example 4 and/or 5. 1.3 kg of reactive colloidal silica (30 wt%) and / or alumina as binders. Slurry was spray-dried at the spray-dryer inlet air temperature of 400 °C and outlet air temperature of approximately 180 °C for 25 minutes to obtain microspheres. The microspheres of the spray-dried material calcined at 600 °C for 3 hours with the ramp rate of 2 °C/min to obtain the attrition resistant high pore volume silica-alumina material. The properties of calcined silica-alumina materials are given in the Table 3 (refer Fig. 1 for the process of preparing of the high pore volume silica-alumina materials by spray-drying).
Example 12: Process for the preparation of attrition resistant high pore volume silica-alumina material in accordance with the present disclosure
2 kg of HPV silica-alumina (on dry basis) slurry batch was prepared. The slurry comprises 40 wt% silica and 60 wt% alumina. This high pore volume silica-alumina precursor was taken from example 9. This slurry comprises of milled silica-alumina precursor powder of average particle size less than 5-micron, 1.3 kg of reactive colloidal silica (30 wt%) as a binder and 20 g of urea as a stabilizer. The final HPV silica-alumina slurry was spray-dried with spray-dryer inlet air temperature of 400 °C and outlet air temperature ~180 °C in 25 minutes. Spray-dried material calcined at 600 °C for 3 hours with the ramp rate of 2 °C/min to obtain attrition resistant high pore volume silica-alumina microspheres. The properties of the calcined silica-alumina material are given in the Table 3.
Example 13: Process for the preparation of attrition resistant high pore volume silica-alumina material in accordance with the present disclosure
2 kg of HPV silica-alumina (on dry basis) slurry batch was prepared which comprises 40 wt% silica and 60 wt% alumina. This high pore volume silica-alumina precursor was obtained from mixtures of example 8, 9 and 10. This slurry comprises milled silica-alumina precursor powder of average particle size less than 5-micron, 1.3 kg of reactive colloidal silica (30 wt%) as a binder and 20 g of Triton X-100 as a slurry stabilizer. The final slurry was spray-dried with spray-dryer inlet air temperature of 400 °C and outlet air temperature approximately 180 °C in 25 minutes. Spray-dried material calcined at 600°C for 3 hours with the ramp rate of 2 °C/min to obtain attrition resistant high pore volume silica-alumina microspheres. The properties of calcined silica-alumina material are given in the Table 3.
Table 3. Physicochemical properties of spray-dried calcined silica-alumina materials
Example No. SiO2/
Al2O3 (wt %) Stabilizer/
additive Attrition Index
(wt %) Average bulk density
(g/cc) Average particle size (µ) Total Pore volume, (cc/g)*
11** 70/30 - >15 0.50 80 0.84
12 40/60 Urea 9 0.53 90 0.74
13 40/60 Triton X-100 7 0.54 100 0.70
*Total pore volume was determined by N2 adsorption-desorption BET method; **comparative example (without stabilizer). Spray-dried silica-alumina materials showed the specific surface area values in the range of 100 m2/g to 400 m2/g.
The spray-dried high pore volume silica-alumina materials are not limited to the silica-alumina composition as mentioned in the Table 3 but can be prepared from 5 wt% to 95 wt% silica and the amount of the alumina can be balanced and vice-versa using high pore volume silica and alumina precursors, reactive binders and slurry stabilizers.
The use of the stabilizers such as urea and triton X-100 improved the attrition index value to <10, which was desirable as shown in the example no. 12 and 13.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a process for the preparation of an attrition resistant high pore volume silica-alumina material that:
• is simple, cost-effective, and efficient;
• is used in fluidized catalytic process;
• provide high pore volume silica-alumina precursor; and
• provides attrition resistant high pore volume silica-alumina materials;
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation. , Claims:WE CLAIM:
1. A process for the preparation of an attrition resistant high pore volume silica-alumina material, said process comprising the following steps:
A) preparing high pore volume silica-alumina precursor by
(a) acidifying colloidal silica particles by using an acid to obtain an acidified silica having a predetermined pH;
(b) separately, preparing an aluminium precursor solution by dissolving an aluminium precursor in water under stirring at a temperature in the range of 20 oC to 40 oC;
(c) adding said aluminium precursor solution to said acidified silica under stirring to obtain a silica-alumina sol;
(d) adding at least one base to said silica-alumina sol to attain a pH in the range of 7 to 8 to obtain a gel;
(e) hydrothermally heating said gel in an autoclave at a first predetermined temperature for a first predetermined time period to obtain a heated gel;
(f) cooling said heated gel to a temperature in the range of 25oC to 40 oC followed by filtering to obtain solids and washing said solids with an aqueous ammonia solution having a pH in the range of 7 to 9 to obtain a wet cake of said high pore volume silica-alumina precursor;
(g) optionally, drying said wet cake at a second predetermined temperature for a second predetermined time period followed by calcining at a third predetermined temperature for a third predetermined time period to obtain said high pore volume silica-alumina precursor;
B) mixing at least one binder, at least one stabilizer and water to said wet cake of said high pore volume silica-alumina precursor of step (f) or said high pore volume silica-alumina precursor of step (g) at a temperature in the range of 25 oC to 40 oC to obtain a slurry;
C) spray drying said slurry at a fourth predetermined temperature for a fourth predetermined time period to obtain a spray dried material in the form of microspheres; and
D) calcining said spray dried material at a fifth predetermined temperature for a fifth predetermined time period with a predetermined ramp rate to obtain said attrition resistant high pore volume silica-alumina material.
2. The process as claimed in claim 1, wherein said acid is at least one selected from the group consisting of nitric acid, sulfuric acid, formic acid, and acetic acid.
3. The process as claimed in claim 1, wherein said acid is a concentrated acid having a concentration of 65% and above.
4. The process as claimed in claim 1, wherein said predetermined pH of said acidified silica is in the range of 2.5 to 4.
5. The process as claimed in claim 1, wherein said colloidal silica is a sodium free silica.
6. The process as claimed in claim 1, wherein said colloidal silica has a particle size in the range of 10 nm to 20 nm.
7. The process as claimed in claim 1, wherein said aluminium precursor is at least one selected from the group consisting of aluminium nitrate, aluminium sulfate, aluminium acetate, aluminium formate, aluminium chloride, aluminium oxide, aluminium oxyhydroxide, and aluminium trihydroxide.
8. The process as claimed in claim 1, wherein a non-ionic surfactant is added to said gel before hydrothermal heating; wherein said non-ionic surfactant is a block copolymer of polyethylene glycol and polypropylene glycol.
9. The process as claimed in claim 1, wherein said base is selected from the group consisting of an aqueous ammonia solution and organic amines.
10. The process as claimed in claim 1, wherein said first predetermined temperature is in the range of 150oC to 200oC.
11. The process as claimed in claim 1, wherein said first predetermined time period is in the range of 20 hours to 30 hours.
12. The process as claimed in claim 1, wherein said second predetermined temperature is in the range of 100 oC to 150 oC.
13. The process as claimed in claim 1, wherein said second predetermined time period is in the range of 6 hours to 24 hours.
14. The process as claimed in claim 1, wherein said third predetermined temperature is in the range of 500 oC to 700 oC.
15. The process as claimed in claim 1, wherein said third predetermined time period is in the range of 1 hour to 5 hours.
16. The process as claimed in claim 1, wherein said binder is selected from the group consisting of reactive colloidal silica, and psuedoboehmite alumina.
17. The process as claimed in claim 1, wherein said stabilizer is selected from the group consisting of urea, ammonium carbonate, ammonium bicarbonate, sodium hexametaphosphate, polycarboxylate ether, citric acid, oxalic acid, ammonium salt of polyacrylic acid, polydiallydimethylammonium chlorides, hexamethylene tetraamine (HMTA), ethylene diamine tetra-acetic acid (EDTA), polyacrylamide and their derivatives.
18. The process as claimed in claim 17, wherein said surfactant is selected from octylphenol ethylene oxide condensate, cetrytrimethylammonium bromide, block copolymer of polyethylene glycol and polypropylene glycol, and octylphenol ethoxylate.
19. The process as claimed in claim 1, wherein said slurry has a solid content in the range of 10 mass% to 30 mass%, and said slurry has water content in the range of 70 mass% to 90 mass%.
20. The process as claimed in claim 1, wherein said fourth predetermined temperature is in the range of 150oC to 450oC; and said fourth predetermined time period is in the range of 15 minutes to 60 minutes.
21. The process as claimed in claim 20, wherein said spray drying is done by using a spray dryer having an inlet temperature in the range of 350 oC to 450 oC and an outlet temperature in the range of 150 oC to 200 oC.
22. The process as claimed in claim 1, wherein said fifth predetermined temperature is in the range of 500oC to 700 oC; and said fifth predetermined time period is in the range of 1 hour to 5 hours.
23. The process as claimed in claim 1, wherein said predetermined ramp rate is in the range of 1oC/min to 5 oC/min.
24. An attrition resistant high pore volume silica-alumina material is characterized by having
a. an attrition index less than 10%;
b. a pore volume greater than 0.7 cc/g; and
c. a specific surface area in the range of 100 m2/g to 400 m2/g.

Dated this 03rd day of February, 2024

_______________________________
MOHAN RAJKUMAR DEWAN, IN/PA – 25
of R.K.DEWAN & CO.
Authorized Agent of Applicant

TO,
THE CONTROLLER OF PATENTS
THE PATENT OFFICE, AT MUMBAI