WO2021165884A1

WO2021165884A1 - A method for nano-silica production

Info

Publication number: WO2021165884A1
Application number: PCT/IB2021/051401
Authority: WO
Inventors: Karim ONIY AGHMIUNI; Taher RAHIMI AGHDAM; Omid KARBALAEE
Original assignee: Oniy Aghmiuni Karim; Rahimi Aghdam Taher; Karbalaee Omid
Priority date: 2020-02-19
Filing date: 2021-02-18
Publication date: 2021-08-26

Abstract

A method for producing a participated nano-silica has been developed. The method comprises at least sixth steps including preparation of a first solution, preparation of a second solution such that the first solution comprises at least one precursor of silicon and the second solution comprises at least one acid, mixing the first and the second solution in at least one reactor in at least three steps to obtain a slurry, filtrating the slurry to obtain a cake, drying the cake to obtain a dried silicate cake, and disintegrating the dried cake to achieve the participated nano silica. The produced participated nano-silica has a particle size less than 100 nm.

Description

A method for nano-silica production

The present disclosure application claims priority from IR Patent Application, Application No 139850140003010810, filed on 19 February, 2020, which is incorporated by reference herein in its entirety

The present subject matter is, in general, related to production of chemical materials, and more particularly, but not exclusively, to a method for producing of a participated nano-silica with a particle size less than 100 nm.

Precipitated nano-silica is one of the most used nanoparticles in many industries such as tire and rubber industries, toothpaste, paints and coatings, cement and concrete, cosmetics, plastics, papers, food industries, and construction. However, the most rapidly growing usage of the participated silica is for the plastic market, especially the tire industry due to the decrease in the application of carbon black and the development of green tires in the automobile industries of the world.

These days, the substitution of amorphous precipitated silica materials for carbon black as the reinforcing filler has a growing trend in the tire industry, particularly for formulating the tread of tires of passenger and lorry cars. The particular property of the surface area of silica compared to carbon black cases different mechanical properties compared to carbon black due to the interaction between silica and elastomer. Using silica alone causes a significant increase in a viscosity of the compounds and leads to problems in the processing and vulcanization operations. Therefore, using silica as a filler accompanied by silane functionalities has been favorable to improve processability and reinforcing performance. So that, in order to balance out the rolling resistance, slippage, and abrasion resistance properties of tires, silica-filled compounds are used widely

As mentioned above, Precipitated silica has been used for a long time as a reinforcing filler in different elastomers. Obviously, the reinforcing filler needs to be distributed well throughout the polymer matrix to achieve the properties suitable for the elastomeric matrix. Nevertheless, one of the fundamental problems associated with this kind of fillers is the ability to distribute favorably in elastomeric matrices. Another problem associated with producing a nanostructure of this kind of fillers is obtaining an utterly uniform structure with a particle size less than 100 nm as well as mesoporous pores.

Different methods and raw materials can be used to synthesize a plurality of silica nanoparticles in the laboratory scale. However, different pricey reactants used for synthesizing the nanoparticles in the laboratory cannot be used to produce the nanoparticles on an industrial scale because using such reactants is not cost-effective, and process control can be proved to be problematic for preparing the products. In addition, using these reactants on higher scales is also of concern due to environmental issues. Therefore, a more facile and environmental-friendly method is required that can be used to produce the silica nanoparticles on the industrial scale.

Then, a continues, cost-effective, environmental-friendly method for producing a participated nano-silica on the industrial scale has been developed such that can produce the participated nano-silica with the particle size less than 100 nm.

This summary is intended to provide an overview of the subject matter of this application, and is not intended to identify essential elements or key elements of the subject matter, nor is it intended to be used to determine the scope of the claimed implementations. The proper scope of this application may be ascertained from the claims set forth below in view of the detailed description below and the drawings.

In one general aspect, the present disclosure is directed to an exemplary method for producing of a participated nano-silica. The exemplary method may comprise preparing a first solution comprising at least one precursor of silicon and water, preparing a second solution comprising at least one acid and water, mixing the first solution and the second solution in at least three steps such that a slurry may obtain, filtering the slurry to remove a salt residual and obtain a cake of silicone, drying the cake of silicon to obtain a dried silicate cake, and disintegrating the dried silicate cake to obtain the participated nano-silica.

The above general aspect may have one or more of the following features. In an exemplary implementation, the precursor of silicon may comprise any type of silicate salt. In an exemplary implementation, the precursor of silicon may comprise a mixture of at least two silicate salts. In an exemplary implementation, the acid may comprise at least one organic acid, at least one inorganic acid, or a mixture thereof. In an exemplary implementation, the three steps of mixing may comprise mixing the first solution and the second solution in any order such that a pH value of a mixed solution may be adjusted in a range of 9 to 12, adding the first solution and the second solution in any order such that the pH value of the mixed solution may be adjusted in a range of 7 to 10, and adding the second solution such that the pH value may be adjusted in a range of 4 to 6. In an exemplary implementation. the three steps of the mixing may be performed in a temperature in a range of 40-90 °C. in an exemplary implementation, drying the cake may be performed utilizing a spin flash drier, a rotary drum drier, an atomizer, or a fluid bed drier. In an exemplary implementation, mixing of the first and the second solution may be performed in a continuous condition, a semi- continuous condition, or a discontinuous condition. In an exemplary implementation, the participated nano-silica may comprise a plurality of specific properties. In an exemplary implementation, the specific properties may include BET specific surface area in a range of 50-350 m ².g ^-1, CTAB specific surface area in a range of 50-300 m ².g ^-1, a particle size in a range of 10-100 nm, an agglomerate size in a range of 1-100 μm, a minimum pore size of 15 nm, and a minimum pore volume of 1.2 cm ³.g ^-1. In an exemplary implementation, disintegrating the dried silicate cake may be performed utilizing a grinding device, a granulation device, or a combination thereof.

In another general aspect, the present disclosure is directed to an exemplary method for producing of a participated nano-silica. The exemplary method may comprise preparing a first solution comprising at least one precursor of silicon and water, preparing a second solution comprising at least one acid and water, mixing the first solution and the second solution in at least three steps to obtain a slurry, such that the three steps may comprise mixing the first solution and the second solution in any order such that a pH value of a mixed solution may be adjusted in a range of 9 to 12, adding the first solution and the second solution in any order such that the pH value of the mixed solution may be adjusted in a range of 7 to 10, and adding the second solution such that the pH value may be adjusted in a range of 4 to 6, and the three steps may be performed in a temperature in a range of 40 to 90 °C, obtaining a cake of silicon utilizing a filtering step of the slurry. The exemplary method may further comprise drying the cake of silicon to obtain a dried silicate cake, and disintegrating the dried silicate cake to obtain the participated nano-silica.

The above general aspect may have one or more of the following features. In an exemplary implementation, the precursor of silicon may comprise at least one silicate salt, a mixture thereof, or any type of silicate salt. In an exemplary implementation, the acid may comprise at least one organic acid, at least one inorganic acid, or a mixture thereof. In an exemplary implementation, drying the cake may be performed utilizing a spin flash drier, a rotary drum drier, an atomizer, or a fluid bed drier. In an exemplary implementation, mixing of the first and the second solutions may be performed in a continuous condition, a semi- continuous condition, or a discontinuous condition. In an exemplary implementation, the participated nano-silica may comprise a plurality of specific properties. In an exemplary implementation, the specific properties may include BET specific surface area in a range of 50-350 m ².g ^-1, CTAB specific surface area in a range of 50-300 m ².g ^-1, a particle size in a range of 10-100 nm, an agglomerate size in a range of 1-100 μm, a minimum pore size of 15 nm, and a minimum pore volume of 1.2 cm ³.g ^-1. In an exemplary implementation, disintegrating the dried silicate cake may be performed utilizing a grinding device, a granulation device, or a combination thereof.

The drawing figures depict one or more implementations in accordance with the present teachings, by way of example only, not by way of limitation. In the figures, like reference numerals refer to the same or similar elements.

Fig.1

illustrates a flowchart of an exemplary method for producing of a participated nano-silica, consistent with one or more exemplary embodiments of the present disclosure.

Fig.2

illustrates a flowchart of an exemplary three steps of mixing, consistent with one or more exemplary embodiments of the present disclosure.

Fig.3

illustrates an X-ray pattern of a participated nano-silica, consistent with one or more exemplary embodiments of the present disclosure.

Fig.4

illustrates FESEM images of a participated nano-silica in two different magnifications, consistent with one or more exemplary embodiments of the present disclosure.

Fig.5

illustrates EDS spectrum of a participated nano-silica, consistent with one or more exemplary embodiments of the present disclosure.

Fig.6

illustrates element mapping of a participated nano-silica, consistent with one or more exemplary embodiments of the present disclosure.

In the following detailed description, numerous specific details are set forth by way of examples in order to provide a thorough understanding of the relevant teachings. However, it should be apparent that the present teachings may be practiced without such details. In other instances, well-known methods, procedures, components, and/or circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present teachings. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present disclosure is defined only by the appended claims.

The following detailed description is presented to enable a person skilled in the art to make and use the methods and apparatuses disclosed in exemplary embodiments of the present disclosure. For purposes of explanation, specific nomenclature is set forth provide a thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that these specific details are not required to practice the disclosed exemplary embodiments. Descriptions of specific exemplary embodiments are provided only as representative examples. Various modifications to the exemplary implementations will be readily apparent to one skilled in the art, and the general principles defined herein may be applied to other implementations and applications without departing from the scope of the present disclosure. The present disclosure is not intended to be limited to the implementations shown, but is to be accorded the widest possible scope consistent with the principles and features disclosed herein.

illustrates a flowchart of an exemplary method 100 for production of a participated nano-silica, consistent with one or more exemplary embodiments of the present disclosure. In an exemplary embodiment, the exemplary method 100 may comprise preparation of a first solution that may comprise at least one precursor of silicon 102, preparation of a second solution that may comprise at least on acid 104. In this exemplary embodiment, the exemplary method 100 may further comprise mixing the first aquas solution and the second aquas solution in at least three steps to obtain a slurry 106. Afterward, the exemplary method may comprise filtering the slurry such that may remove a salt residual and obtain a cake of silicon 108. Furthermore, the exemplary method 100 may further comprise drying the cake of silicon to obtain a dried silicate cake 110 and disintegrating the dried silicate cake to obtain the participated nano-silica 112.

In an exemplary embodiment, the first solution may comprise any type of silicate salt, for example, but not limited to, sodium silicate, potassium silicate. In an exemplary embodiment, the first solution may comprise a mixture of at least two precursors of silicon. In an exemplary embodiment, the precursor of silicon may comprise at least one silicate salt. In an exemplary embodiment, the precursor of silicon may comprise any kinds of silicon compound that are well known for those skilled in the art.

In an exemplary embodiment, a concentration of the precursor in the first solution may be in a range of 2% to 10% by weight. In an exemplary embodiment, the concentration of the precursor in the first solution may be at least 4% by weigh.

In an exemplary embodiment, the acid of the second solution may comprise at least one organic acid, for example, but not limited to, acetic acid, citric acid, oxalic acid and other inorganic acids that are well known for those skilled in the art. In an exemplary embodiment, the acid may comprise at least one inorganic acid, for example, but not limited to sulfuric acid, hydrochloric acid, nitric acid, and other inorganic acids that are well known for those skilled in the art. In an exemplary embodiment, the second solution may comprise a mixture of at least two acids. In this exemplary embodiment, the at least two acids may comprise at least two organic acids, at least two inorganic acids, and/or a combination thereof. In an exemplary embodiment, the second solution may comprise a mixture of at least one organic acid and at least one inorganic acid.

In an exemplary embodiment, a concentration of the acid in the second solution may be in a range of 2% to 30% by mass. In an exemplary embodiment, the concentration of the acid in the second solution may be at least 2% by mass.

illustrates an exemplary three steps 200 of mixing the first solution and the second solution 106, consistent with one or more exemplary embodiments of the present disclosure. In an exemplary embodiment, as illustrated in , the three steps 200 may comprise mixing the first solution and the second solution in any order such that a pH value of a mixed solution may be adjusted in a range of 9 to 12 (202), adding the first solution and the second solution in any order such that the pH value of the mixed solution may be adjusted in a range of 7 to 10 (204), and adding the second solution such that the pH value may be adjusted in a range of 4 to 6 (206).

In an exemplary embodiment, the three steps 200 of mixing the first and the second solution 106 may be performed utilizing at least one reactor. In this exemplary embodiment, the 202, 204 and 206 steps may be done in a semi-continuous condition and/or a discontinuous condition. In an exemplary embodiment, the three steps 200 of mixing the first and the second solution 106 may be performed utilizing at least three reactors such that the reactors may be provided a continuous condition to progress mixing the first and second solutions 106. In an exemplary embodiment, the reactors may operate in the semi-continuous condition and/or the discontinuous condition. In an exemplary embodiment, the first solution and the second solution may be added into the reactors in any order or simultaneously in both

steps

202 and 204. In an exemplary embodiment, the reactors may comprise at least one agitator such that the agitator may be configured to stirrer the first and the second solution to obtain the mixed solution, introduce the mixed solution as well as creating a backflow. In an exemplary embodiment, the agitator may comprise an axial agitator and/or a radial agitator. In an exemplary embodiment, the agitator may comprise a jet rotary agitator. In an exemplary embodiment, the reactor may comprise at least one axial or radial agitator and the rotary jet agitator. In an exemplary embodiment, the reactor may comprise a turbine agitator, an anchor agitator, a propeller agitator, a blade agitator, a universal agitator, and/or other agitators that are well known for those skilled in the art.

In an exemplary embodiment, the slurry resulted from step 10 8 may comprise at least 2% by weigh of dispersed silica in water. In an exemplary embodiment, the slurry may be filtered utilizing a separation process such as, but not limited to, filter press, rotary vacuum, drum filter, and other processes that are well known for those skilled in the art, to remove at least one impurity and obtain the cake of silicone. In an exemplary embodiment, the impurity may comprise any residual precursors of silicon such as any unreacted silicate salts, any formed salts during the mixing and reaction of the first and the second solutions. In an exemplary embodiment, the step 108 may be performed at least two times. In this exemplary embodiment, the obtained cake of silicon may be dispersed again into water and a pH value of a prepared suspension may be adjusted in a range of 6 to 7 utilizing a third solution and the prepared suspension may be filtered. In an exemplary embodiment, the third solution may comprise at least one alkali and water.

In an exemplary embodiment, a concentration of the silicon in the cake of silicon may be in a range of 15% to 22% by weight. In an exemplary embodiment, the concentration of the silicon in the cake of silicon may be at least 15% by weight.

In an exemplary embodiment, the cake of silicon may be dried to obtain the dried silicate cake (step 110) utilizing a drier apparatus. In an exemplary embodiment, the drier apparatus may comprise a spin flash drier, a rotary drum drier, an atomizer, a fluid bed drier, and/or other drier apparatuses that are well known for those skilled in the art. In an exemplary embodiment, the step 110 may be performed in a temperature in a range of 150 to 450 °C.

In an exemplary embodiment, the dried silicate cake may contain a concentration of moisture less than 10% by weight. In an exemplary embodiment, the dried silicate cake may be disintegrated (step 112) utilizing a grinding device, a granulation device, or a combination thereof such that the participated nano-silica may be obtained.

In an exemplary embodiment, the participated nano-silica may comprise a plurality of specific properties. In this exemplary embodiment, the specific properties may comprise BET specific surface area in a range of 50-350 m ².g ^-1, CTAB specific surface area in a range of 50-300 m ².g ^-1, a particle size in a range of 10-100 nm, an agglomerate size in a range of 1-100 μm, a minimum pore size of 15 nm, and a minimum pore volume of 1.2 cm ³.g ^-1.

Examples

EXAMPLE 1: Production of Nano-Silica Utilizing One Reactor and A Rotary Jet Agitator

30-liters silicate compound that contain a silicate concentration about 5% by weigh and 50-liters water was mixed to prepared a first solution (step 102). Then, a second solution was prepared such that the second solution contain a concentration of an acid about 2% by mass (step 104). Then, in first step of adding the solutions to the reactor (step 202), 80 liters of the first solution and 20 liters of the second solution were added into the reactor at a temperature of 60 °C and a first mixed solution was obtained. A pH value of the first mixed solution was adjusted in a range of 10-11. Follow that, in the second step of adding (step 204), the first solution and the second solution were added to the first mixed solution to obtain a second mixed solution such that the pH value of the second mixed solution was adjusted in a range of 8-9. Subsequently, the pH value of the second mixed solution was adjusted around 5 by adding the second solution to the reactor in the third step of adding (step 206) such that a slurry was obtained (step 106). In next step, the slurry that contain a plurality of silicate particles was filtered and washed to remove existing impurities such as residual silicate salts or silicates compound, and/or unreacted acid and a cake of silicon was obtained (step108). Afterward, the cake was dispersed in the water again and the pH value of the suspension was increased to a range of 6-5. Then. The filtration was carried out one more time and a final cake of silicon was dried utilizing a flash drier and a dried silicate cake was obtained (step 110) that had a humidity lower than 5% by weight. In final step (step 112), the dried silicate cake was grinded utilizing a mill and characterization tests was caried out.

Results of Characterization Experiments
X-ray Powder Diffraction (XRD)

illustrates a XRD pattern for produced precipitated nano-silica. As illustrated in the XRD pattern, a broad peak was appeared at 2θ about 22 degrees that the peak a characteristic peak for formation of participated nano-silica. Other prominent peaks related to impurities were not observed in the XRD pattern that confirmed the exemplary method has been caried out well and the participated nano-silica with a high quality was produced.
Field Emission Scanning Electron Microscope (FESEM)

A surface morphology of the produced participated nano-silica was investigated utilizing FESEM. illustrates two FESEM images of the participated nano-silica in two different magnifications. As illustrated in , the participated nano silica particles have a particle size less than 100 nm.
Energy-dispersive X-ray spectroscopy (EDS)

EDS and element mapping were applied to investigate composition elements and distribution pattern of the elements, respectively. The results of the EDS and element mapping are illustrated in and , respectively. The results show that the produced participated nano-silica was mainly composed of silicon, oxygen, and the elements such as aluminum, sodium, and sulfur are existing weight percent less than 2% weight.
BET Surface Analysis

Specific surface area, pore volume, and average pore diameter of nano-silica particles were investigated utilizing BET surface Analysis. The results of BET were reported in Table.1 below:

Parameter	Value	Unit
Specific surface area	172.19	[m ² g ^-1]
Pore volume (p/p ₀=0.990)	1.0865	[cm ³ g ^-1]
Average pore size	25.239	[nm]

:

Claims

A method for producing a participated nano-silica, comprising:
preparing a first solution comprising at least one precursor of silicon and water;
preparing a second solution comprising at least one acid and water;
mixing the first solution and the second solution in at least three steps to obtain a slurry;
filtering the slurry to remove a salt residual and obtain a cake of silicone;
drying the cake of silicon to obtain a dried silicate cake; and
disintegrating the dried silicate cake to obtain the participated nano-silica.
The method according to claim 1, wherein the precursor of silicon comprises any type of silicate salt.
The method according to claim 1, wherein the precursor of silicon comprises a mixture of at least two silicate salts.
The method according to claim 1, wherein the acid comprises at least one organic acid, at least one inorganic acid, or a mixture thereof.
The method according to claim 1, wherein the three steps of mixing comprise:
mixing the first solution and the second solution in any order wherein a pH value of a mixed solution is adjusted in a range of 9 to 12;
adding the first solution and the second solution in any order wherein the pH value of the mixed solution is adjusted in a range of 7 to 10; and
adding the second solution wherein the pH value is adjusted in a range of 4 to 6.
A method according to claim 1 and 5, wherein the three steps of the mixing is performed in a temperature in a range of 40-90 °C.
The method according to claim 1, wherein drying the cake is performed utilizing a spin flash drier, a rotary drum drier, an atomizer, or a fluid bed drier.
The method according to claim1, wherein the mixing is performed in a continuous condition, a semi- continuous condition, or a discontinuous condition.
The method according to claim 1, wherein the participated nano-silica comprises a plurality of specific properties including BET specific surface area in a range of 50-350 m ².g ^-1, CTAB specific surface area in a range of 50-300 m ².g ^-1, a particle size in a range of 10-100 nm, an agglomerate size in a range of 1-100 μm, a minimum pore size of 15 nm, and a minimum pore volume of 1.2 cm ³.g ^-1.
The method according to claim 1, wherein disintegrating the dried silicate cake is performed utilizing a grinding device, a granulation device, or a combination thereof.
A method for producing of a participated nano-silica, comprising:
preparing a first solution comprising at least one precursor of silicon and water;
preparing a second solution comprising at least one acid and water;
mixing the first solution and the second solution in at least three steps to obtain a slurry,
wherein the three steps comprise:
mixing the first solution and the second solution in any order wherein a pH value of a mixed solution is adjusted in a range of 9 to 12;
adding the first solution and the second solution in any order wherein the pH value of the mixed solution is adjusted in a range of 7 to 10; and
adding the second solution wherein the pH value is adjusted in a range of 4 to 6,
wherein the three steps are performed in a temperature in a range of 40 to 90 °C;
obtaining a cake of silicon utilizing a filtering step of the slurry;
drying the cake of silicon to obtain a dried silicate cake; and
disintegrating the dried silicate cake to obtain the participated nano-silica.
The method according to claim 11, wherein the precursor of silicon comprises at least one silicate salt, a mixture thereof, or any type of silicate salt.
The method according to claim 11, wherein the acid comprises at least one organic acid, at least one inorganic acid, or a mixture thereof.
The method according to claim 1, wherein drying the cake is performed utilizing a spin flash drier, a rotary drum drier, an atomizer, or a fluid bed drier.
The method according to claim 11, wherein the mixing is performed in a continuous condition, a semi- continuous condition, or a discontinuous condition.
The method according to claim 11, wherein the participated nano-silica comprises a plurality of specific properties including BET specific surface area in a range of 50-350 m ².g ^-1, CTAB specific surface area in a range of 50-300 m ².g ^-1, a particle size in a range of 10-100 nm, an agglomerate size in a range of 1-100 μm, a minimum pore size of 15 nm, and a minimum pore volume of 1.2 cm ³.g ^-1.
The method according to claim 11, wherein disintegrating the dried silicate cake is performed utilizing a grinding device, a granulation device, or a combination thereof.