CN1420082A

CN1420082A - Process for preparing active alumina

Info

Publication number: CN1420082A
Application number: CN 02158286
Authority: CN
Inventors: 方维平; 盛景云; 王跃敏
Original assignee: Xiamen University
Current assignee: Xiamen University
Priority date: 2002-12-19
Filing date: 2002-12-19
Publication date: 2003-05-28
Anticipated expiration: 2022-12-19
Also published as: CN1168659C

Abstract

A process for preparing the active aluminium oxide includes preparing the solution of sodium metaaluminate from powdered aluminium hydroxide and sodium hydroxide, introducing high-concentration CO2 gas mixture, colloidizing at 20-70 deg.C, regulating pH=9-11, filtering, washing the filtered cake, drying at 60-100 deg.C to obtain alpha-AlO(OH), and calcining at 500-700 deg.C. Its advantages are high reaction speed, low CO2 consumption and low cost.

Description

A kind of preparation method of activated alumina

(1) technical field

The present invention relates to a kind of preparation method of activated alumina.

(2) background technology

Activated alumina refers to γ-Al ₂O ₃, η-Al ₂O ₃And composition thereof.Because activated alumina has flourishing hole and good thermostability, is widely used in support of the catalyst and siccative and sorbent material etc.During the preparation activated alumina, general its precursor---the pseudo-boehmite of preparation earlier carries out high-temperature roasting again and makes it the crystalline phase conversion.In the various methods that prepare pseudo-boehmite, minimum with sodium metaaluminate and carbonic acid gas neutralisation cost, declared many patents with regard to this method both at home and abroad.The disclosed production technique of CN1057443A patent application wherein, its master operation be feedstock production, become glue, aging, washing, solid-liquid separation and drying.This technology is in becoming the glue process, and the sour gas that feeds sodium metaaluminate is for containing CO ₂The CO of 35～45% (V) ₂-air Mixture.Because CO in the gas mixture ₂Content is lower, and the neutralization reaction time is long, generates gibbsite easily, makes the finished product porosity low, and made activated alumina product pore volume is less than 0.75mlg ^-1The CN1254684A patent application is used low temperature (15～25 ℃) and low sodium aluminate solution (20～35g Al instead for solving the low problem of product porosity ₂O ₃L ^-1), but still adopt lower concentration CO ₂And air Mixture, the side effect that this method is brought is: when 1) produce summer, must use cooling apparatus, increase energy expenditure; 2) production efficiency is lower.The prepared activated alumina pore volume of this method is 0.88mlg to the maximum ^-1

(3) summary of the invention

Purpose of the present invention aims to provide the preparation method of the activated alumina that a kind of technology is simple, production cost is low, the product porosity is high.

Its step of the preparation method of the said activated alumina of the present invention is as follows:

1) be mixed with dense sodium aluminate solution with aluminium hydrate powder (gibbsite) and sodium hydroxide, the causticity of control solution is than [NaOH/Al (OH) ₃] be 1.2～1.5mol, get the dense sodium aluminate solution for preparing, being diluted to concentration with deionized water is 15～75gAl ₂O ₃L ^-1, preferably be controlled at 25～50Al ₂O ₃L ^-1

2) 0%～8% of the adding vehicle weight water glass or sodium phosphate or dobell's solution in the sodium aluminate solution of dilution.

3) gained solution is placed in the reactor, feed CO by the reactor bottom ₂The CO of content 〉=90% (V) ₂Gas mixture adds agitator and stirs, and becomes the glue temperature to be controlled at 20～70 ℃, is preferably 30～60 ℃, regulates CO ₂The feeding amount of gas mixture when the pH value reaches 9～11, is preferably at 9.5～10.5 o'clock, stops to feed CO ₂Gas mixture.

4) with step 3 gained dope filtration, and to use deionized water wash filter cake, the water yield be 20 times of filter cake.

5) under 60～100 ℃, best 70～90 ℃ of down dry filter cakes by step 4 gained no longer dewater to filter cake, obtain pseudo-boehmite.

6) will be by step 5 gained material in 450～800 ℃, best 500～700 ℃ of roasting 2～6h promptly obtain activated alumina.

The present invention adopts high concentration CO ₂Mix pneumatolytic glue, neutralization reaction speed is accelerated, gelation time shortens greatly, avoids or suppress the generation of gibbsite.Simultaneously since gelation time shorten, thereby the restriction that can make into the glue temperature relax, can save the cooling apparatus of production process; Because gelation time shortens, produce the CO of pseudo-boehmite per ton in addition ₂Consumption slightly descends, and improves the production unit utilization ratio or can reduce the volume of colloid generating kettle, greatly reduces production cost.In addition, when made activated alumina is used as support of the catalyst, sometimes need to add second component such as Si, P and B etc. carry out modulation to carrier surface character (solid acid concentration), so before becoming glue, in the sodium aluminate solution of dilution, add water glass or sodium phosphate or dobell's solution, and then feeding contains CO ₂Gas be neutralized into glue.By its porosity of activated alumina of explained hereafter provided by the present invention greater than 0.85mlg ^-1

(4) embodiment

Embodiment 1

Get industrial one-level aluminium hydrate powder and [contain Al ₂O ₃63% (w)] 150g and 40% (w) NaOH aqueous solution 148g, add deionized water 230g and under agitation be heated to 100 ℃, constant temperature 120min dissolves fully to aluminium hydroxide that to obtain concentration be 270gAl ₂O ₃L ^-1Sodium aluminate solution (NaOH/Al (OH) ₃The mol ratio is 1.3), being diluted to concentration with deionized water again is 25gAl ₂O ₃L ^-1Sodium aluminate solution, being controlled to the glue temperature is 60 ℃, feeds to contain CO ₂The CO of 98% (V) ₂-air gas mixture also adds agitator and stirs, and (needs 18min) and stop to feed gas and stirring when the pH value reduces to 10.2, and slurries carry out conventional solid-liquid separation, and filter cake is washed till neutrality with 60 ℃ of deionized waters, 90 ℃ of dry 8h, and 550 ℃ of roasting 3h promptly get γ-Al ₂O ₃, its main character is listed in table 1.

Embodiment 2

The preparation method is identical with embodiment 1, with dense sodium aluminate solution concentration dilution to 50g Al ₂O ₃L ^-1, the gained result lists table 1 in.

Reference example 1～2

In embodiment 1, with dense sodium aluminate solution concentration dilution to 75g Al ₂O ₃L ^-1With 85g Al ₂O ₃L ^-1, the products obtained therefrom main character is listed in table 1.

Table 1 embodiment 1～3 and reference example 1 product main character

Sample	Sodium aluminate solution concentration/lgAl ₂O ₃·L ^-1	Pore volume/mlg ^-1	Specific surface/m ²·g ^-1	The thing phase
Sample	Sodium aluminate solution concentration/lgAl ₂O ₃·L ^-1	Pore volume/mlg ^-1	Specific surface/m ²·g ^-1	The thing phase	Embodiment 1	????25	??0.964	????288	????γ-Al ₂O ₃
Embodiment 2	????50	??0.850	????272	????γ-Al ₂O ₃	Embodiment 1	????25	??0.964	????288	????γ-Al ₂O ₃
Embodiment 2	????50	??0.850	????272	????γ-Al ₂O ₃	Reference example 1	????75	??0.778	????265	????γ-Al ₂O ₃
Reference example 2	????85	??0.721	????220	7% gibbsite and γ-Al ₂O ₃	Reference example 1	????75	??0.778	????265	????γ-Al ₂O ₃

Implement 3～5

Changing over the glue temperature is 30 ℃, 45 ℃, 70 ℃, and all the other are with embodiment 1, product main character such as table 2.

Reference example 3: become the glue temperature to change 85 ℃ into, i.e. cost example, products obtained therefrom main character such as table 2.

Table 2 embodiment 4～6 and reference example 2 product main character

Sample	One-tenth glue temperature/℃	Pore volume/mlg ^-1	Specific surface/m ²·g ^-1	The thing phase
Sample	One-tenth glue temperature/℃	Pore volume/mlg ^-1	Specific surface/m ²·g ^-1	The thing phase	Embodiment 3	???30	????1.06	????293	???γ-Al ₂O ₃
Embodiment 4	???45	????0.990	????292	???γ-Al ₂O ₃	Embodiment 3	???30	????1.06	????293	???γ-Al ₂O ₃
Embodiment 4	???45	????0.990	????292	???γ-Al ₂O ₃	Embodiment 5	???70	????0.943	????275	???γ-Al ₂O ₃
Reference example 3	???85	????0.821	????260	8% gibbsite and γ-Al ₂O ₃	Embodiment 5	???70	????0.943	????275	???γ-Al ₂O ₃

Embodiment 6～8

In embodiment 1, add water glass, sodium phosphate and dobell's solution in the sodium aluminate solution after dilution respectively, the products obtained therefrom main character is listed in table 3.

Table 3 embodiment 7～9 product main character

Sample	Second component concentration/wt%	Pore volume/mlg ^-1	Specific surface/m ²·g ^-1	The thing phase
Sample	Second component concentration/wt%	Pore volume/mlg ^-1	Specific surface/m ²·g ^-1	The thing phase	Embodiment 6	??SiO ₂??4	????0.983	????285	????γ-Al ₂O ₃
Embodiment 7	??P ₂O ₅?4	????1.02	????282	????γ-Al ₂O ₃	Embodiment 6	??SiO ₂??4	????0.983	????285	????γ-Al ₂O ₃
Embodiment 7	??P ₂O ₅?4	????1.02	????282	????γ-Al ₂O ₃	Embodiment 8	??B ₂O ₃?5	????0.993	????305	????γ-Al ₂O ₃

Reference example 4: in embodiment 1, the CO of used gas mixture ₂Concentration changes 40% into, and required time is 35min.Its product main character sees Table 4.

The comparison of table 4 embodiment 1 and reference example 3

Sample	Gas mixture CO ₂Concentration/% (V)	Become glue required time/min	Pore volume/mlg ^-1	Specific surface/m ²·g ^-1	The thing phase
Sample	Gas mixture CO ₂Concentration/% (V)	Become glue required time/min	Pore volume/mlg ^-1	Specific surface/m ²·g ^-1	The thing phase	Embodiment 1	??95	??18	????0.964	????288	??γ-Al ₂O ₃
Reference example 3	??40	??35	????0.705	????195	12% gibbsite and γ-Al ₂O ₃	Embodiment 1	??95	??18	????0.964	????288	??γ-Al ₂O ₃

Claims

1. the preparation method of an activated alumina makes activated alumina with carbonic acid gas by sodium metaaluminate after becoming the glue reaction, it is characterized in that said preparation method's step is as follows:

1) be mixed with dense sodium aluminate solution with aluminium hydrate powder and sodium hydroxide, the causticity of control solution is than [NaOH/Al (OH) ₃] be 1.2～1.5mol, get the dense sodium aluminate solution for preparing, being diluted to concentration with deionized water is 15～75gAl ₂O ₃L ^-1

2) 0%～8% of the adding vehicle weight water glass or sodium phosphate or dobell's solution in the sodium aluminate solution of dilution;

3) gained solution is placed in the reactor, feed CO by the reactor bottom ₂The CO of content 〉=90% (V) ₂Gas mixture adds agitator and stirs, and becomes the glue temperature to be controlled at 20～70 ℃, regulates CO ₂The feeding amount of gas mixture when the pH value reaches 9～11, stops to feed CO ₂Gas mixture;

4) with step 3 gained dope filtration, and to use deionized water wash filter cake, the water yield be 20 times of filter cake;

5) at 60～100 ℃ of down dry filter cakes by step 4 gained, no longer dewater to filter cake, obtain pseudo-boehmite;

6) will be by step 5 gained material in 450～800 ℃, roasting 2～6h promptly obtains activated alumina.

2. the preparation method of a kind of activated alumina as claimed in claim 1, the concentration that it is characterized in that sodium aluminate solution in the step 1 is 25～50Al ₂O ₃L ^-1

3. the preparation method of a kind of activated alumina as claimed in claim 1 is characterized in that becoming in the step 3 the glue temperature to be controlled at 30～60 ℃.

4. the preparation method of a kind of activated alumina as claimed in claim 1 is characterized in that the pH value is controlled at 9.5～10.5 stopped reaction in the step 3.

5. the preparation method of a kind of activated alumina as claimed in claim 1 is characterized in that the drying temperature in the step 5 is 70～90 ℃.

6. the preparation method of a kind of activated alumina as claimed in claim 1 is characterized in that the maturing temperature in the step 6 is 500～700 ℃.