CN101927194B - Preparation method of aluminum hydroxide powder containing lanthanum, phosphorus and titanium elements - Google Patents

Abstract

The invention relates to a preparation method of aluminum hydroxide powder containing lanthanum-phosphorus-titanium element, which is characterized by the following steps: preparing sodium metaaluminate solution; preparing an aqueous solution of a compound containing lanthanum; preparing an aqueous solution of a compound containing phosphorus; preparing Titanium-containing compound suspension; under stirring conditions, carbon dioxide gas is passed into sodium metaaluminate solution, lanthanum-containing compound aqueous solution, phosphorus-containing compound aqueous solution and titanium-containing compound suspension. The reaction is carried out in the mixed solution to form a precipitate; the above-mentioned solid-liquid mixture is filtered, and the filtered solid is washed, dried and pulverized to obtain aluminum hydroxide powder containing lanthanum-phosphorus-titanium element. The prepared aluminum hydroxide powder containing lanthanum-phosphorus-titanium element is very uniform due to the combination of lanthanum-phosphorus-aluminum element, so that the hydrofining catalyst containing lanthanum-phosphorus-titanium element is more than that without lanthanum-phosphorus-titanium element. Titanium hydrorefining catalysts have better low-temperature catalytic activity; larger pore volume and specific surface area.

Description

Preparation method of aluminum hydroxide powder containing lanthanum-phosphorus-titanium element

technical field

The invention relates to a method for preparing aluminum hydroxide powder containing lanthanum-phosphorus-titanium elements, and belongs to the field of chemical catalysts.

Background technique

The distillate oil hydrotreating catalyst in petroleum refining and the distillate oil hydrofinishing catalyst based on coal oil basically use activated alumina as the carrier. With the continuous deterioration of the quality of distillate oil to be processed, due to the limitation of the performance of activated alumina itself, it is more and more difficult for pure alumina carrier to meet the special performance requirements of various hydrorefining catalysts. The requirements for the carrier of hydrofining catalysts are that they should have large pore volume and specific surface area; moderate surface acid strength and good low-temperature catalytic activity, so as to meet the long-term stable operation of the catalyst under harsh service conditions . Due to the relatively poor thermal stability of the pure alumina carrier, the pore volume and specific surface area will decrease rapidly with the increase of the temperature under the normal pressure heating state with the increase of the calcination temperature. The alumina carrier of most hydrogenation catalysts is required to be calcined at a higher temperature to meet the requirements of the catalyst for the acid strength and phase of the carrier surface, and the smaller pore volume and specific surface area of the alumina carrier are relatively small. A large limit limits the catalyst's reactivity and long-term stable operation.

In addition, while the catalyst maintains a high catalytic activity, it is more desirable that the catalyst has good low-temperature catalytic activity. Pure alumina support is difficult to meet the requirements of the catalyst on the performance of the support.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for preparing aluminum hydroxide powder containing lanthanum-phosphorus-titanium element. Excellent thermal stability and moderate surface acid strength; large pore volume and specific surface area; good low-temperature catalytic activity and selectivity.

The technical scheme adopted by the present invention to solve its technical problems is: provide a kind of preparation method of aluminum hydroxide powder containing lanthanum-phosphorus-titanium element, its feature comprises the following steps:

(1) Prepare a sodium metaaluminate solution with a concentration of 10-45gAl ₂ O ₃ /l;

(2) preparing an aqueous solution of a lanthanum-containing compound whose lanthanum-containing concentration is 0.1 to 10 gLa/l;

(3) preparing an aqueous solution of a compound containing phosphorus with a phosphorus concentration of 0.1 to 10 gP/l;

(4) preparing a titanium-containing compound suspension with a titanium-containing concentration of 5 to 15 gTi/l;

(5) Under stirring conditions, carbon dioxide gas is passed into sodium metaaluminate solution, the compound aqueous solution containing lanthanum element, the compound aqueous solution containing phosphorus element and the compound suspension liquid containing titanium element are jointly formed and reacted, A precipitate is generated, and the composition of the precipitate based on the product is: Al ₂ O ₃ 68-95.6 wt%, La ₂ O ₃ 0.2-6.0 wt%, P ₂ O ₅ 2-9 wt%, TiO ₂ 2-17 wt% , during the reaction process, the volume concentration of carbon dioxide gas is 10-40%, after the reaction, the pH value of the mixed solution is 8-12, and the reaction temperature is maintained at 5-40°C during the entire reaction process;

(6) Filter the solid-liquid mixture produced in step (5), and wash, dry and pulverize the filtered solid to obtain aluminum hydroxide powder containing lanthanum-phosphorus-titanium element.

The aqueous solution of the compound containing lanthanum in the step (2) is an aqueous solution of sulfate, nitrate, acetate or chloride containing lanthanum.

The aqueous solution of the phosphorus-containing compound in the step (3) is an aqueous solution of phosphate.

The titanium element-containing compound suspension in the step (4) is a suspension of titanium oxide or metatitanic acid. Among them, metatitanic acid is preferred, and before the metatitanic acid is formulated into a titanium-containing compound suspension at a desired concentration, it should be ground with a colloid mill so that the particle size of the titanium-containing compound passes through a sieve of 800 mesh. Since the titanium-containing compound suspension is acidic, the pH value should be adjusted with an alkaline solution before being added to the reaction solution, and the pH value should be adjusted between 7 and 12, preferably between 9 and 10. The alkaline solution for adjusting the pH value can be aqueous solutions such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, ammoniacal liquor, wherein the aqueous solution of sodium bicarbonate and ammoniacal liquor is preferred.

The aqueous solution of the compound containing lanthanum, the aqueous solution of the compound containing phosphorus and the suspension of the compound containing titanium are added to the sodium metaaluminate solution during the process of feeding carbon dioxide gas, wherein the compound containing titanium is suspended The solution was finally added to the reaction mixture slurry. The addition of the lanthanum-containing compound solution is added to the reaction solution during the reaction, preferably in the middle of the reaction. The phosphorus-containing compound solution is added to the reaction solution during the reaction, preferably after the addition of the lanthanum-containing compound solution, and then added to the reaction solution. The titanium-containing compound suspension is added to the reaction solution during the reaction, preferably at the later stage of the reaction.

The aqueous solution of the compound containing lanthanum element in the step (2) is based on the product, and the content of the lanthanum element is calculated as lanthanum oxide and accounts for 0.2-6.0% of the total mass. Wherein the content of lanthanum element is preferably between 0.3% and 4%.

In the step (3), the phosphorus-containing compound aqueous solution is based on the product, and the phosphorus content is calculated as phosphorus pentoxide, accounting for 2-9% of the total mass. Wherein the content of phosphorus element is preferably 3-6%.

In the step (4), the titanium element-containing compound suspension is based on the product, and the content of the titanium element is calculated as titanium dioxide, accounting for 2-17% of the total mass. Wherein the content of titanium element is preferably 4-12%.

The washing temperature in the step (6) is 50-80°C, and the sodium oxide content in the washed product is less than 0.2wt%.

Among them, the preferred washing temperature is 60-75°C, and the sodium oxide content is preferably 0.03-0.1 wt%.

The drying method in the step (6) is normal pressure dynamic drying, the drying temperature is 50-150° C., the drying time is 0.5-1.5 hours, and the pulverization is jet pulverization, and the particle size of the pulverized product is 80-300 mesh.

The above preferred drying temperature is 100-130°C, the preferred drying time is 0.4-2.0 hours, and the preferred product particle size is 120-200 mesh.

The concentration of the above sodium metaaluminate solution is 10˜45 g Al ₂ O ₃ /l, preferably 15˜35 g Al ₂ O ₃ /l.

The above-mentioned carbon dioxide gas volume concentration is 10 to 40%, preferably 15 to 35%.

During the whole reaction process, the reaction temperature is kept at 5-40°C, preferably 15-30°C, and the pH value at the end of the reaction is controlled at 8-12, preferably 9-11.

The beneficial effects of the present invention are: the introduction of lanthanum-containing, phosphorus-containing, and titanium-containing compounds in the reaction process of sodium metaaluminate solution and carbon dioxide has simple preparation process, easy operation, no pollutant removal, and no environmental pollution; the produced The aluminum hydroxide powder containing lanthanum-phosphorus-titanium element is very uniform due to the combination of lanthanum-phosphorus-aluminum element, so that the hydrofining catalyst containing lanthanum-phosphorus-titanium element is better than that without lanthanum-phosphorus-titanium element The hydrorefining catalyst has better low-temperature catalytic activity; it has larger pore volume and specific surface area.

Detailed ways

Example 1

Add 10g of Al ₂ O ₃ /l sodium metaaluminate solution into the reactor, and control the temperature of the solution at 40°C. Under agitation, carbon dioxide gas with a concentration of 10% (v) was introduced to react. When the pH value of the reaction solution reached 12, adding a concentration of lanthanum acetate aqueous solution of 0.1gLa/l. After the aqueous solution of lanthanum acetate has been added, an aqueous solution of ammonium dihydrogen phosphate having a concentration of 10 gP/l is then added. After adding the ammonium dihydrogen phosphate aqueous solution, then add the metatitanic acid suspension with a concentration of 5 gTi/l and a pH value of 10.

Continue feeding carbon dioxide gas to react, when the pH value of the reaction solution reaches 8, stop the reaction. The precipitate that generates is based on the composition of the product: Al ₂ O ₃ 88.8wt%, La ₂ O ₃ 0.2wt%, P ₂ O ₅ 9wt%, TiO ₂ 2wt%, the precipitate is filtered, with deionized water Washing at 50°C, the sodium oxide content in the product after washing is 0.03wt%. Dry with a dynamic dryer at a temperature of 50°C for 1.5 hours. The dried product is pulverized to 300 orders with a jet mill, and both obtain the product of the present invention.

Example 2

Add 45g Al ₂ O ₃ /l sodium metaaluminate solution into the reactor, and control the solution temperature at 5°C. Under agitation, carbon dioxide gas with a concentration of 4O% (v) was introduced to carry out the reaction. When the pH value of the reaction solution reached 11, adding a concentration of lanthanum nitrate aqueous solution was 10gLa/l. After the aqueous solution of lanthanum nitrate has been added, an aqueous solution of diammonium hydrogen phosphate having a concentration of 0.1 gP/l is then added. After adding the diammonium hydrogen phosphate aqueous solution, a titanium oxide suspension with a concentration of 17 gTi/l and a pH value of 10 was then added.

Continue feeding carbon dioxide gas to react, when the pH value of the reaction solution reaches 10, stop the reaction. The composition of the generated precipitate based on the product is: Al ₂ O ₃ 75 wt%, La ₂ O ₃ 6 wt%, P ₂ O ₅ 2 wt%, TiO ₂ 17 wt%. The resulting precipitate was filtered and washed with deionized water at 80° C., and the sodium oxide content in the product after washing was 0.2 wt%. Dry with a dynamic dryer at a temperature of 150°C for 0.5 hours. The dried product was pulverized to 80 orders with a jet mill, and both obtained the product of the present invention.

Example 3

Add 30g Al ₂ O ₃ /l sodium metaaluminate solution into the reactor, and control the solution temperature at 30°C. Under stirring, carbon dioxide gas with a concentration of 30% (v) was introduced to react. When about 20 minutes after the start of the reaction, an aqueous solution of lanthanum chloride having a concentration of 4 gLa/l was added. After the aqueous solution of lanthanum chloride has been added, a solution of ammonium dihydrogen phosphate with a concentration of 6 gP/l is then added. After the addition of the ammonium dihydrogen phosphate solution, a titanium oxide suspension with a concentration of 10 gTi/l and a pH value of 11 was added.

Continue feeding carbon dioxide gas to react, when the pH value of the reaction solution reaches 12, stop the reaction. The precipitate that generates is based on the composition of the product: Al ₂ O ₃ 78wt%, La ₂ O ₃ 3wt%, P ₂ O ₅ 7wt%, _TiO 12wt%, the precipitate is filtered, and deionized water is used at 70 ℃ washing, the sodium oxide content in the product after washing is less than 0.08wt%. Dry for 1 hour at a temperature of 120° C. using a dynamic dryer. The dried product is pulverized to 120 orders with a jet mill, and both obtain the product of the present invention.

Example 4

Add 20g Al ₂ O ₃ /l sodium metaaluminate solution into the reactor, and control the solution temperature at 15°C. Under agitation, carbon dioxide gas with a concentration of 25% (v) is introduced to react. When the pH value of the reaction solution reached 12, adding a concentration of lanthanum acetate aqueous solution was 2gLa/l. After adding the aqueous lanthanum chloride solution, a solution of diammonium hydrogen phosphate with a concentration of 2 gP/l was then added. After adding the diammonium hydrogen phosphate solution, the metatitanic acid suspension with a concentration of 4 gTi/l and a pH value of 12 was then added.

Continue feeding carbon dioxide gas to react, when the pH value of the reaction solution reaches 11, stop the reaction. The composition of the generated precipitate based on the product is: Al ₂ O ₃ 86 wt%, La ₂ O ₃ 2 wt%, P ₂ O ₅ 4 wt%, TiO ₂ 8 wt%. The precipitate is filtered and washed with deionized water at 65°C, and the sodium oxide content in the product after washing is less than 0.12wt%. Dry with a dynamic dryer at a temperature of 110° C. for 0.7 hours. The dried product was pulverized to 200 orders with a jet mill, and both obtained the product of the present invention.

Comparative example 1

In Example 3, except that phosphorus, lanthanum, and titanium element compounds were not added, other reaction processes and control conditions remained unchanged.

Alumina carrier samples were prepared by using the lanthanum-phosphorus-titanium-containing aluminum hydroxide powder prepared in Examples 1-4 and the pure aluminum hydroxide powder prepared in Comparative Example 1, respectively. Weigh aluminum hydroxide powder with oxide weight of 100 grams, add 4 grams of scallop powder, 3 grams of glacial acetic acid and an appropriate amount of deionized water, knead and extrude cylindrical strips of Φ2.0. After the strips were dried at 120°C for 4 hours, they were baked in a muffle furnace at 750°C for 4 hours. Power failure, natural temperature down to normal temperature, corresponding to the preparation of lanthanum-phosphorous or pure alumina carrier samples. Under the same conditions, the acid strength, pore volume and specific surface area of these samples were measured, and the results are listed in Table 1.

Table 1: Acid strength, pore volume and specific surface area of alumina supports

Sample serial number  Total acid strength, mmolpy/g Pore volume, ml/g Specific surface area, m2/g Example 1 0.316 0.724 356 Example 2 0.272 0.658 295 Example 3 0.305 0.685 312 Example 4 0.292 0.705 331 Comparative example 1 0.125 0.604 278

As can be seen from Table 1, under the same preparation conditions, the lanthanum-phosphorus-titanium alumina carrier produced by the lanthanum-phosphorous-titanium aluminum hydroxide powder prepared by the present invention has a larger total acid strength, pore volume and specific surface area.

Using the impregnation method, under the same operating conditions, 12 grams of molybdenum oxide, 20 grams of tungsten oxide and 4 grams of nickel oxide were loaded on the alumina carriers of Example 1 and Comparative Example 1 respectively to prepare two coal tar fractions Hydrofining catalyst. Using high temperature coal tar distillate as raw material, under the process conditions of hydrogen partial pressure of 15Mpa, liquid space velocity of 0.3h ^-1 , and hydrogen-to-oil ratio (v/v) of 1500, the catalytic activity of hydrotreating was evaluated. The catalyst in Example 1 had a desulfurization rate of 99.3% and a nitrogen removal rate of 84% at a reaction temperature of 360°C; the catalyst in Comparative Example 1 had a desulfurization rate of only 85% and a nitrogen removal rate of only 81% at a reaction temperature of 385°C. The evaluation results show that when the reaction temperature of the catalyst of Example 1 is 25°C lower than that of the catalyst of Comparative Example 1, its hydrodesulfurization rate and hydrodenitrogenation rate are still higher than those of the catalyst of Comparative Example 1. The nitrogen rate is high, which shows that the catalyst made of the aluminum hydroxide powder containing lanthanum-phosphorus-titanium element of the present invention does have good low-temperature catalytic activity.

Claims (7)

1. preparation method who contains lanthanum-phosphorus-titanium elements aluminium hydroxide powder, its feature may further comprise the steps:

(1) compound concentration is 10～45g Al ₂O ₃The sodium aluminate solution of/l;

(2) preparation contains the compound water solution that contains lanthanum element that lanthanum element concentration is 0.1～10gLa/l;

(3) preparation phosphorus element-containing concentration is the compound water solution of the phosphorus element-containing of 0.1～10gP/l;

(4) preparation titaniferous concentration of element is the titanium-containing compound suspension of 5～15gTi/l;

(5) under stirring condition, carbon dioxide is fed sodium aluminate solution, contains in the compound water solution of compound water solution, phosphorus element-containing of lanthanum element and the common mixed solution of forming of titanium-containing compound suspension and react, generate sediment, this sediment is consisting of of benchmark: Al with the product ₂O ₃68～95.6wt%, La ₂O ₃0.2-6.0wt%, P ₂O ₅2～9wt%, TiO ₂2～17wt%, in the course of reaction, feeding the carbon dioxide volumetric concentration is 10～40%, and after reaction finished, the pH value of mixed liquor was 8～12, and it is 5～40 ℃ that entire reaction course keeps reaction temperature;

(6) solid-liquid mixtures that produces in the step (5) is filtered, and wash leaching solid, dry, pulverize, make and contain lanthanum-phosphorus-titanium elements aluminium hydroxide powder.

2. the preparation method who contains lanthanum-phosphorus-titanium elements aluminium hydroxide powder according to claim 1 is characterized in that the compound water solution that contains lanthanum element in the described step (2) is sulfate, nitrate, acetate or the muriatic aqueous solution that contains lanthanum element.

3. the preparation method who contains lanthanum-phosphorus-titanium elements aluminium hydroxide powder according to claim 1, the compound water solution that it is characterized in that the phosphorus element-containing in the described step (3) is the phosphatic aqueous solution.

4. the preparation method who contains lanthanum-phosphorus-titanium elements aluminium hydroxide powder according to claim 1 is characterized in that the titanium-containing compound suspension in the described step (4) is the suspension of titanium oxide or metatitanic acid.

5. the preparation method who contains lanthanum-phosphorus-titanium elements aluminium hydroxide powder according to claim 1, it is characterized in that describedly containing the compound water solution of lanthanum element, the compound water solution and the titanium-containing compound suspension of phosphorus element-containing is to join in the sodium aluminate solution in carbon dioxide feeding process, wherein titanium-containing compound suspension joins in the reaction mixed serum at last.

6. the preparation method who contains the lanthanum element aluminium hydroxide powder according to claim 1 is characterized in that the wash temperature in the described step (6) is 50～80 ℃, and the sodium oxide content in the product of washing back is less than 0.2wt%.

7. the preparation method who contains the lanthanum element aluminium hydroxide powder according to claim 1, it is characterized in that the drying mode in the described step (6) is that normal pressure is dynamically dry, baking temperature is 50～150 ℃, be 0.3～1.5 hour drying time, and pulverize to air-flow and pulverize, pulverizing the back product granularity is 80～300 orders.