阅读说明：本技术 一种小晶粒拟薄水铝石及其制备方法、氧化铝 (Small-grain pseudo-boehmite, preparation method thereof and alumina ) 是由 周峰 李广战 王少武 韩皓 孔杰 蔡军 姚毅 于 2021-08-06 设计创作，主要内容包括：本发明提供了一种小晶粒拟薄水铝石及其制备方法、氧化铝,方法包括：将铝酸钠溶液和二氧化碳气体进行两段碳酸化分解反应,得到拟薄水铝石碳化浆液,所述碳酸化分解反应的终点pH值10～11.5；所述二氧化碳气体的通入流量为1.0m～(3)/h～5.0m～(3)/h；将所述拟薄水铝石碳化浆液进行老化反应,后固液分离,得到小晶粒拟薄水铝石。该方法通过控制分解反应条件,将终点pH值控制在10～11.5,利用两段碳酸化反应来控制原晶粒的生成,通过温控控制晶粒长大,利用高温对碳化液进行长时间老化处理,后经洗涤烘干粉碎包装等制得在进行酸化时更加均匀,所得铝溶胶目测透彻,具有良好的胶溶性能。(The invention provides a small-grain pseudo-boehmite, a preparation method thereof and alumina, wherein the method comprises the following steps: performing two-stage carbonation decomposition reaction on the sodium aluminate solution and carbon dioxide gas to obtain pseudo-boehmite carbonation slurry, wherein the pH value of the endpoint of the carbonation decomposition reaction is 10-11.5; the flow rate of the carbon dioxide gas is 1.0m 3 /h～5.0m 3 H; and carrying out aging reaction on the pseudoboehmite carbonized slurry, and carrying out solid-liquid separation to obtain the small-grain pseudoboehmite. The method comprises the steps of controlling the decomposition reaction condition, controlling the end-point pH value to be 10-11.5, controlling the generation of original crystal grains by utilizing two-stage carbonation reaction, controlling the growth of the crystal grains by controlling the temperature, carrying out long-time aging treatment on a carbonated solution by utilizing high temperature, washing, drying, crushing, packaging and the like to obtain the product In the process ofThe acidification is more uniform, and the obtained aluminum sol has thorough visual inspection and good peptization performance.)

1. A preparation method of small-grain pseudo-boehmite is characterized by comprising the following steps:

performing two-stage carbonation decomposition reaction on the sodium aluminate solution and carbon dioxide gas to obtain pseudo-boehmite carbonation slurry, wherein the end point pH value of the carbonation decomposition reaction is controlled to be 10-11.5, and the introduction flow of the carbon dioxide gas is 1.0m³/h～5.0m³/h；

And carrying out aging reaction on the pseudoboehmite carbonized slurry, and carrying out solid-liquid separation to obtain the small-grain pseudoboehmite.

2. The method for preparing small-grained pseudoboehmite according to claim 1, characterized in that Al in said sodium aluminate solution₂O₃The concentration of (B) is 10g/L to 50 g/L.

3. The method of claim 1, wherein the two-stage carbonation decomposition reaction comprises: a first stage carbonation decomposition reaction and a second stage carbonation decomposition reaction;

in the one-stage carbonation decomposition reaction, CO₂The flow rate is controlled to be 1.0m³/h～4.0m³H, controlling the initial temperature to be 10-25 ℃, controlling the final temperature to be 15-30 ℃ and controlling the reaction time to be 0-15 min;

in the two-stage carbonation decomposition reaction, CO₂The flow rate is controlled to be 1.5m³/h～5.0m³The initial temperature is controlled to be 15-30 ℃, the final temperature is controlled to be 15-30 ℃, and the reaction time is 1-20 min.

4. The method for preparing the small-grain pseudo-boehmite according to claim 1, wherein in the aging reaction, the reaction temperature is 90 ℃ to 100 ℃ and the reaction time is 2h to 40 h.

5. The method for preparing small-grained pseudoboehmite according to claim 1, characterized in that it further comprises, after solid-liquid separation:

and washing the solid obtained by the solid-liquid separation by using soft water at the temperature of 80-100 ℃ until the pH value of the solid is 7.0-7.5.

6. The method for preparing small-grain pseudo-boehmite according to claim 1, wherein the sodium aluminate solution is obtained by dissolving an aluminum hydroxide raw material and a liquid caustic soda at a temperature of 102-120 ℃ and diluting and blending.

7. A small grained pseudoboehmite prepared by the method of any one of claims 1-6.

8. The small grained pseudoboehmite according to claim 7, characterized in that the small grained pseudoboehmite has a grain size of ≦

9. An alumina obtained by calcining the small-grained pseudoboehmite according to any one of claims 7 to 8.

Technical Field

The invention relates to the technical field of non-metallurgical alumina preparation, in particular to small-grain pseudo-boehmite, a preparation method thereof and alumina.

Background

The pseudo-boehmite can be used as a binder of a semi-synthetic rare earth Y-type molecular sieve cracking catalyst, a binder of aluminum silicate refractory fibers, a catalyst for preparing ethylene by alcohol dehydration, an ethylene oxide catalyst and the like, and can also be used as a raw material for producing a catalyst carrier, active alumina and other aluminum salts.

At present, the company applies carbonization method to produce ordinary pseudo-boehmite, namely CO is introduced into sodium aluminate solution₂Carbonating and decomposing the gas to generate pseudo-boehmite slurry, aging, filtering, washing, drying and crushing to obtain the common pseudo-boehmite product with the grain size ofAnd the requirements of various users with special requirements cannot be met.

Therefore, how to develop a small-grain pseudo-boehmite with a lower grain size and a preparation method thereof becomes a technical problem to be solved urgently.

Disclosure of Invention

The invention aims to provide small-grain pseudo-boehmite, a preparation method thereof and alumina, and the small-grain pseudo-boehmite

In order to achieve the above object, the present invention provides a method for preparing small-grain pseudo-boehmite, comprising:

performing two-stage carbonation decomposition reaction on the sodium aluminate solution and carbon dioxide gas to obtain pseudo-boehmite carbonation slurry, wherein the pH value of the endpoint of the carbonation decomposition reaction is controlled to be 10-11.5; the above-mentionedThe flow rate of carbon dioxide gas is 1.0m³/h～5.0m³/h；

Carrying out aging reaction on the pseudoboehmite carbonized slurry, and then carrying out solid-liquid separation to obtain small-grain pseudoboehmite

Further, Al of the sodium aluminate solution₂O₃The concentration of (B) is 10g/L to 50 g/L.

Further, the two-stage carbonation decomposition reaction comprises: a first stage carbonation decomposition reaction and a second stage carbonation decomposition reaction;

in the one-stage carbonation decomposition reaction, CO₂The flow rate is controlled to be 1.0m³/h～4.0m³H, controlling the initial temperature to be 10-25 ℃, controlling the final temperature to be 15-30 ℃ and controlling the reaction time to be 0-15 min;

in the two-stage carbonation decomposition reaction, CO₂The flow rate is controlled to be 1.5m³/h～5.0m³The initial temperature is controlled to be 15-30 ℃, the final temperature is controlled to be 15-30 ℃, and the reaction time is 1-20 min.

Further, in the aging reaction, the reaction temperature is 90-100 ℃, and the reaction time is 2-40 h.

Further, the method further comprises the following steps after solid-liquid separation:

and washing the solid obtained by the solid-liquid separation by using soft water at the temperature of 80-100 ℃ until the pH value of the solid is 7.0-7.5.

Further, the sodium aluminate solution is obtained by dissolving an aluminum hydroxide raw material and liquid caustic soda at the temperature of 102-120 ℃, and diluting and blending.

The invention also provides the small-grain pseudo-boehmite prepared by the method.

Further, the small-grain pseudo-boehmite

The invention also provides alumina, which is obtained by roasting the small-grain pseudo-boehmite.

One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

the invention provides a small-grain pseudo-boehmite and a preparation method thereof, wherein the method comprises the following steps: performing two-stage carbonation decomposition reaction on the sodium aluminate solution and carbon dioxide gas to obtain pseudo-boehmite carbonation slurry, wherein the pH value of the endpoint of the carbonation decomposition reaction is controlled to be 10-11.5; the flow rate of the carbon dioxide gas is 1.0m³/h～5.0m³H; and carrying out aging reaction on the pseudoboehmite carbonized slurry, and then carrying out solid-liquid separation and washing to obtain the small-grain pseudoboehmite. The method comprises the steps of controlling the decomposition reaction conditions, controlling the pH value of the end point to be 10-11.5, controlling the generation of original crystal grains by utilizing two-stage carbonation reaction, controlling the growth of the crystal grains by controlling the temperature, carrying out long-time aging treatment on a carbonized liquid by utilizing high temperature, washing, drying, crushing, packaging and the like to obtain the small-crystal-grain pseudo-boehmiteThe acidification is more uniform, and the obtained aluminum sol is visual and has good peptization performance.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to derive other drawings without creative efforts.

FIG. 1 is a flow chart of a method for preparing small-grained pseudoboehmite according to an embodiment of the present invention;

fig. 2 is a flow chart of a method for preparing small-grain pseudo-boehmite according to an embodiment of the present invention.

Detailed Description

The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that these specific embodiments and examples are for the purpose of illustrating the invention and are not to be construed as limiting the invention.

Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. If there is a conflict, the present specification will control.

Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.

In order to solve the technical problems, the embodiment of the invention provides the following general ideas:

in order to achieve the above object, the present embodiment provides a method for preparing small-grained pseudoboehmite, comprising:

step S1, preparation of sodium aluminate solution: and controlling the temperature to be between 102 and 120 ℃, and dissolving an aluminum hydroxide raw material and liquid caustic soda at high temperature to obtain a sodium aluminate solution. Then, adding the sodium aluminate solution into a blending tank, diluting and blending the sodium aluminate solution with distilled water, and controlling Al of the sodium aluminate₂O₃The concentration is 10-50 g/L. If Al is present₂O₃The concentration of less than 10g/L is difficult to control because the reaction process and the end point duration are short, and the slurry after the reaction is too thin, thereby greatly influencing the production capacity. And Al₂O₃The concentration of the slurry is more than 50g/L, so that the slurry is too viscous to lose good fluidity in the aging process of the carbonization liquid, and the next process is difficult to carry out.

And step S2, putting the sodium aluminate solution into a carbonation decomposition tower, and carrying out two-stage carbonation decomposition reaction, wherein the pH value of the reaction end point is controlled to be 10-11.5, so as to obtain the pseudo-boehmite carbonation slurry.

The two-stage carbonation decomposition reaction comprises: a first stage carbonation decomposition reaction and a second stage carbonation decomposition reaction;

in the one-stage carbonation decomposition reaction, CO₂The flow rate is controlled to be 1.0m³/h～4.0m³H, the initial temperature is controlled to be 10-25 ℃, and the final temperature is controlled to be 15 ℃The reaction time is 0min to 15min at 30 ℃;

in the two-stage carbonation decomposition reaction, CO₂The flow rate is controlled to be 1.5m³/h～5.0m³The initial temperature is controlled to be 15-30 ℃, the final temperature is controlled to be 15-30 ℃, and the reaction time is 1-20 min.

The reasons for the above technical scheme are divided into two stages of carbonation decomposition reaction:

the carbonation decomposition of the pseudo-boehmite is divided into three stages of an induction stage, a seed crystal nucleation stage and a seed crystal growth stage, and the one-stage carbonation reaction is completed in the induction stage and the seed crystal nucleation early stage; in the first-stage carbonation reaction, the initial temperature of the sodium aluminate solution is controlled at 10-25 ℃ and CO is controlled₂The flow rate is controlled to be 1.0-4.0 m³H, completion of sodium aluminate solution and CO₂The gas is rapidly mixed, and a large amount of micro-crystal nuclei explode in the early stage of seed crystal nucleation;

the two-stage carbonation reaction is completed at the later stage of seed crystal nucleation and the initial stage of seed crystal growth, and in the two-stage carbonation reaction, the reaction temperature of slurry is controlled to be 15-30 ℃, and CO is controlled₂The flow rate is controlled to be 1.5 to 5.0m³And h, in order to control the original crystal grains generated in the decomposition reaction to slowly grow, and simultaneously, the pH value of the reaction end point is controlled to be 10-11.5, the final temperature is controlled to be 15-30 ℃, so that the carbonization liquid can be smoothly aged and qualified.

If the initial temperature is less than 10 ℃, CO₂The flow rate is less than 1m³The reaction time is too long, and a large amount of micro-crystal nuclei cannot burst; if the initial temperature is higher than 30 ℃, CO₂The flow rate is more than 5m³The rapid growth of the subsequent crystal grains due to the large amount of outbreak of the microcrystal core is not beneficial to the subsequent control of the original crystal grains in the productWithin the range.

Controlling the pH of the reaction end point to be 10-11.5 is important for the crystal phase purity of the finally formed pseudoboehmite, the pseudoboehmite with a crystal phase purity can be prepared in the pH range, a large amount of dawsonite heterophases are formed in the product when the pH is less than 10, and a large amount of gibbsite heterocrystals exist in the pseudoboehmite prepared with the pH more than 11.5.

The embodiment of the invention is divided into two sections of carbonation decomposition reactions, which is more favorable for controlling the grain size in the product in the follow-up processWithin the range.

Step S3, high-temperature aging process parameters: and heating the slurry to 80-100 ℃, optimally 90-100 ℃, and keeping the residence time in the high-temperature aging tank for 2-40 hours, optimally 6-24 hours. The aging temperature and the aging time give perfect growth conditions to the crystal grains, the higher the value is, the higher the crystallinity is, and the basic aging condition that the crystallinity reaches more than 80 percent is that the temperature is kept for more than 4 hours at 90 ℃.

And (3) after the slurry is aged to be qualified, performing solid-liquid separation in a static washing filter press, performing static washing by using hot water at the temperature of 60-100 ℃, wherein the optimal washing water temperature is 80-100 ℃, the washing water temperature is lower than 80 ℃, the washing effect is greatly reduced, and when the content of sodium oxide in the product is less than or equal to 0.3%, the lower the washing water temperature is, the higher the water consumption is. And unloading the product after the product is washed to be qualified. Finally, drying, crushing, packaging and other processes are carried out to obtain the small-grain pseudo-boehmite product.

The small-grained pseudoboehmite according to the present application and the production method thereof will be described in detail with reference to examples, comparative examples, and experimental data.

Example 1

2L of sodium aluminate solution is prepared, the alumina concentration is 10g/L, and the first-stage aeration speed is 1.0m³H, duration of 3min, second stage aeration speed of 1.5m³H, the time length is 12 min; putting the sodium aluminate solution into a carbon decomposition tower, measuring the initial temperature of the sodium aluminate solution at 25 ℃, starting a cooling device, and turning on CO₂Starting carbonation decomposition by gas inlet valve, controlling total reaction time for 15min, controlling pH to 11 at the end point of reaction, and closing CO₂The gas inlet valve is used for pumping the carbonization liquid into a high-temperature aging tank, heating to 95 ℃ for 20min, and preserving heat for aging for 8 hours; and after the aging is qualified, putting the mixture into a static washing filter press for liquid-solid separation, washing a filter cake with distilled water at 95 ℃ until the filter cake is qualified, and then putting the filter cake into a drying, crushing and packaging product. The performance index of the obtained product is compared with the index of the industry standard product as follows:

TABLE 1 comparison of the invention samples with the industry Standard product indexes

As can be seen from Table 1, the small grain pseudo-boehmite obtained in example 1 of the present inventionAnd all indexes meet the industrial standard.

Example 2

2L of sodium aluminate solution is prepared, the alumina concentration is 40g/L, and the first-stage aeration speed is 1.5m³H, duration 6min, second stage aeration speed 1.8m³H, the time length is 19 min; putting the sodium aluminate solution into a carbon decomposition tower, measuring the initial temperature of the sodium aluminate solution at 15 ℃, starting a cooling device, and turning on CO₂Starting carbonation decomposition by gas inlet valve, controlling total reaction time to 25min, controlling pH to 10 at reaction end point, and closing CO₂The gas inlet valve is used for pumping the carbonization liquid into a high-temperature aging tank, the carbonization liquid is heated to 100 ℃ and takes 25min for heat preservation and aging for 24 hours; and after the aging is qualified, putting the mixture into a static washing filter press for liquid-solid separation, washing a filter cake with distilled water at 100 ℃ until the filter cake is qualified, and then putting the filter cake into a drying, crushing and packaging product. The performance index of the obtained product is compared with the index of the industry standard product as follows:

TABLE 2 comparison of the invention sample with the industry Standard product index

As can be seen from Table 2, the small-grained pseudo-boehmite obtained in example 2 of the present inventionAnd all indexes meet the industrial standard.

Example 3

2L of sodium aluminate solution is prepared, the alumina concentration is 10g/L, and the first-stage aeration speed is 1.0m³H, duration 4min, second stage aeration speed 1.2m³H, the time length is 11 min; putting the sodium aluminate solution into a carbon decomposition tower, measuring the initial temperature of the sodium aluminate solution at 25 ℃, starting a cooling device, and turning on CO₂Starting carbonation decomposition by gas inlet valve, controlling total reaction time to be 15min, controlling pH to be 11.5 at reaction end point, and closing CO₂The gas inlet valve is used for pumping the carbonization liquid into a high-temperature aging tank, heating to 95 ℃ for 20min, and preserving heat for aging for 8 hours; and after the aging is qualified, putting the mixture into a static washing filter press for liquid-solid separation, washing a filter cake with distilled water at 95 ℃ until the filter cake is qualified, and then putting the filter cake into a drying, crushing and packaging product. The performance index of the obtained product is compared with the index of the industry standard product as follows:

TABLE 3 comparison of the invention sample with the industry Standard product index

As can be seen from Table 3, the small grain pseudo-boehmite obtained in example 3 of the present inventionAnd all indexes meet the industrial standard.

Comparative example 1

2L of sodium aluminate solution is prepared, the alumina concentration is 10g/L, and the first-stage aeration speed is 1.0m³H, duration of 3min, second stage aeration speed of 1.5m³H, the time length is 17 min; putting the sodium aluminate solution into a carbon decomposition tower, measuring the initial temperature of the sodium aluminate solution at 25 ℃, starting a cooling device, and turning on CO₂Starting carbonation decomposition by gas inlet valve, controlling total reaction time to be 20min, controlling pH to be 9 at the end point of reaction, and closing CO₂The gas inlet valve is used for pumping the carbonization liquid into a high-temperature aging tank, heating to 95 ℃ for 20min, and preserving heat for aging for 8 hours; and after the aging is qualified, putting the mixture into a static washing filter press for liquid-solid separation, washing a filter cake with distilled water at 95 ℃ until the filter cake is qualified, and then putting the filter cake into a drying, crushing and packaging product. The performance index and the industry standard of the product are obtainedThe product indexes are compared as follows:

TABLE 4-COMPARATIVE EXAMPLE 1 COMPARATIVE EXAMPLES OF SAMPLES AND INDUSTRIAL STANDARD PRODUCTS INDEX

As can be seen from table 4, in comparative example 1, a large amount of dawsonite heterophase was formed in the product obtained when the reaction pH was less than 10.

Comparative example 2

2L of sodium aluminate solution is prepared, the alumina concentration is 40g/L, and the first-stage aeration speed is 1.5m³H, duration of 5min, second stage aeration speed of 1.8m³H, the time length is 11 min; putting the sodium aluminate solution into a carbon decomposition tower, measuring the initial temperature of the sodium aluminate solution at 15 ℃, starting a cooling device, and turning on CO₂Starting carbonation decomposition by gas inlet valve, controlling total reaction time for 16min, controlling pH at reaction end point to 12, and closing CO₂The gas inlet valve is used for pumping the carbonization liquid into a high-temperature aging tank, the carbonization liquid is heated to 100 ℃ and takes 25min for heat preservation and aging for 24 hours; and after the aging is qualified, putting the mixture into a static washing filter press for liquid-solid separation, washing a filter cake with distilled water at 100 ℃ until the filter cake is qualified, and then putting the filter cake into a drying, crushing and packaging product. The performance index of the obtained product is compared with the index of the industry standard product as follows:

TABLE 5-COMPARATIVE EXAMPLE 2 COMPARATIVE EXAMPLES OF SAMPLES AND INDUSTRIAL STANDARD PRODUCTS

As can be seen from Table 5, in comparative example 2, a large amount of gibbsite heterocrystals was present in the pseudo-boehmite prepared at a reaction pH of more than 11.5.

Comparative example 3

Preparing 2L of sodium aluminate solution, the aluminum oxide concentration is 40g/L, putting the sodium aluminate solution into a carbon decomposition tower, measuring the initial temperature of the sodium aluminate solution at 15 ℃, starting a cooling device, and turning on CO₂The gas inlet valve begins to carbonate and decompose, and the aeration speed is 1.8m³H, controlling the total reaction time to be 23min, controlling the pH value of the reaction end point to be 10, and closingCO cut-off₂The gas inlet valve is used for pumping the carbonization liquid into a high-temperature aging tank, the carbonization liquid is heated to 100 ℃ and takes 25min for heat preservation and aging for 24 hours; and after the aging is qualified, putting the mixture into a static washing filter press for liquid-solid separation, washing a filter cake with distilled water at 100 ℃ until the filter cake is qualified, and then putting the filter cake into a drying, crushing and packaging product. The performance index of the obtained product is compared with the index of the industry standard product as follows:

TABLE 6-comparative example 3 product to example 2 product index comparison Table

As can be seen from Table 6, compared with the single-stage carbonation decomposition reaction in the comparative example 3, the two-stage carbonation decomposition reaction in the example 2 is more beneficial to the subsequent control of the grain size in the productWithin the range.

Finally, it should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.