CN104402028A - Forming method for spherical aluminium oxide through oil-water column process - Google Patents

Abstract

The invention relates to a method for forming an oil-water column of spherical alumina, which is characterized in that: adding pseudo-boehmite to an alginate solution and stirring to form an alginic acid-pseudo-boehmite suspension; The material is dropped into the oil-water column composed of the upper oil phase and the lower multivalent metal cation salt solution phase to form composite spherical gel particles; the gel particles are taken out, acid-treated, dried and roasted to obtain spherical alumina products. The method has the advantages of fast molding speed, high efficiency, high product strength, good sphericity, no pollution in the preparation process, simple and feasible operation steps, and easy realization of industrialized production.

Description

A kind of oil-water column forming method of spherical alumina

technical field

The invention relates to the technical field of catalyst carriers, in particular to an oil-water column forming method for spherical alumina, in particular to a forming method for preparing spherical alumina particles by utilizing the sol-gel performance of alginic acid and adopting the oil-water column method.

Background technique

The oil ammonia column method is a common method for preparing spherical alumina, silica and composite supports. It is to drop the sol into the oil ammonia column, the sol particles shrink into balls in the upper oil phase, gel solidify in the lower ammonia water, and the gel particles are aged, dried and roasted to obtain spherical solid particles. The spherical alumina prepared by this method has good sphericity, uniform particle size and high strength, and is widely used as a fixed bed and moving bed catalyst carrier.

Alginic acid is a natural biological material with sol-gel properties and is widely used in the preparation of microcapsules, hydrogels and other materials. The method of preparing spherical alumina particles by alginic acid-assisted molding method was proposed recently. It utilizes the fast sol-gel performance of alginic acid and the embedding performance of the three-dimensional network structure when forming a gel, and carries out spherical alumina particles in the water column. The preparation of particles, compared with the traditional rolling ball method and oil molding method, this molding method has the advantages of fast molding speed, high efficiency, low cost, and no pollution in the preparation process.

USP4542113 discloses a method for preparing spherical alumina particles. In this method, 1 to 10% by weight of urea is added to the aluminum sol, and then dropped into an oily ammonia column to form. Ammonia phase 50-90%.

CN1204964C discloses a method for forming a spherical aluminum oxide column. In this method, alumina sol is dripped into an oily column consisting of an upper oil phase of 0.1 to 4.5 mm and a lower electrolyte solution phase of 10 to 300 cm to form a spherical column. The gel particles are then aged for 0.5-10 hours, then dried and calcined to obtain the product.

CN103011213A discloses a method for preparing spherical alumina by using an oily ammonia column. In this method, aluminum sol and nonionic surfactant are simultaneously dropped into the oily ammonia column to form balls.

CN102718241A discloses a method for preparing spherical alumina by an alginic acid-assisted molding method. In this method, sodium alginate-pseudoboehmite suspension is dropped into aluminum, calcium, barium, copper, zinc, manganese or cobalt ions Molding in aqueous solution, after molding or during the molding process, treat it in an aqueous solution of pH 1~4 for 10~120 minutes to increase the mechanical strength of the product, and then dry and roast to obtain spherical alumina.

The aqueous phase of the above-mentioned oil ammonia column method is ammonia water, and the acidity of the aluminum sol is neutralized by the ammonia water, so that the aluminum sol is gelled. However, ammonia water will volatilize during use and cause environmental pollution, and the strength of sol droplets after gelation in ammonia water is very low, and a long-term aging treatment is required to increase the degree of curing before the next step of drying and other treatments can be carried out, resulting in The preparation time is long and the efficiency is low.

The above-mentioned alginic acid-assisted molding method is a water column molding method, which has high molding efficiency and low cost. However, due to the different binding modes of alginic acid and different metal cations, and the surface tension of the ionic salt solution is also different, resulting in great differences in the sphericity of the gel particles during molding. Among them, the sphericity of the product is better when molded in calcium and zinc ion solutions, but more impurity ions will be introduced, which is not conducive to the preparation of high-purity alumina; when molded in aluminum ion solution, no additional impurity ions will be introduced, but the product Low sphericity. Therefore, the purity and sphericity of the product cannot be taken into account by this method.

Contents of the invention

The purpose of the present invention is to provide a method for preparing spherical alumina by the oil-water column method to solve the problems of long aging time, low efficiency and environmental pollution of the oil-ammonia column method described in the technical background, and the product purity of the alginic acid-assisted molding method Problems that cannot be balanced with sphericity.

The invention is a method for forming an oil-water column of spherical alumina, which is characterized in that: adding pseudo-boehmite and a pore-enlarging agent into an alginate solution, and stirring evenly to prepare a suspension of alginic acid-pseudo-boehmite Slurry; drop the suspension slurry into the oil-water column composed of the upper oil phase and the lower polyvalent metal cation salt solution phase to form composite spherical gel particles; take out the gel particles and treat them with an acidic solution; finally dry and roast Obtain spherical alumina product;

Wherein: the pore-enlarging agent is urea, urotropine, cellulose or activated carbon, and the amount of the pore-enlarging agent is 0-10% of the mass of pseudo-boehmite;

The alginate is one or more of sodium alginate, potassium alginate, magnesium alginate, and ammonium alginate, and the concentration of alginate is 0.3-5% by weight;

The quality of the pseudo-boehmite is 5% to 30% of the quality of the alginic acid solution;

The multivalent metal cation salt solution is a salt solution of aluminum, zinc, calcium, copper, iron, ferrous, cobalt, manganese or nickel ions at a concentration of 0.1mol/L to saturation, preferably 0.2 to 1mol/L of aluminum and zinc , calcium, copper or cobalt ion salt solution;

The oil phase is preferably one or more of kerosene, diesel oil, lubricating oil, heptane, octane, and liquid paraffin, and the height of the oil phase is 0.1 mm to 20 cm;

The hydrogen ion concentration of the acidic solution is 0.0001-2 mol/L, and the treatment time is 1-120 minutes, preferably 0.01-1 mol/L nitric acid solution, and the treatment time is 5-30 minutes.

The drying temperature in the above technical solution is preferably 80-120°C, and the calcination temperature is preferably 450-800°C.

Compared with the prior art, the inventive method has the beneficial effects of:

① The present invention combines the advantages of both the oily ammonia column method and the alginic acid-assisted method, and has the advantages of fast molding speed, high efficiency, high product strength, good sphericity, a wide range of particle sizes that can be prepared, and no pollution in the preparation process;

②The operation steps are simple and feasible, and it is easy to realize industrialized production.

Detailed ways

The oil-water column forming method of spherical alumina of the present invention will be further described below in conjunction with specific examples, but the present invention is not limited thereto.

In the examples, the particle sphericity is expressed by Zingg index, and Zingg index is defined as the ratio of particle length to flatness. Among them, the length is the ratio of the long and short diameters, and the flatness is the ratio of the short diameter to the thickness.

Example 1

Prepare spherical alumina by the method step of the present invention:

100 g of SB powder (pseudo-boehmite) produced by Sasol, Germany, was added to 300 g of a 3% by weight sodium alginate solution, fully stirred to form an alginate-pseudo-boehmite suspension, and set aside.

In the oil-water column with a height of 1.2m and a diameter of 30cm, the upper oil phase is lubricating oil with a height of 1mm, and the lower water phase is a 0.5mol/L aluminum nitrate solution with a height of 119cm. A pump is used to control the oil level to be stable.

Drop the alginic acid-pseudoboehmite suspension from the top of the oil-water column through a ball dropper. The drip nozzle at the bottom of the ball dropper is 2cm away from the oil surface. /Second. Suspension droplets shrink into balls in the oil phase, and smoothly pass through the oil-water interface into the water phase, and the droplets gel into solids in the water phase, and are discharged from the lower outlet of the column along the liquid flow.

Treat the gel particles with 0.01mol/L nitric acid solution for 10 minutes, take them out, dry at 80°C for 10 hours, dry at 120°C for 4 hours, and bake at 550°C for 4 hours to obtain γ-A ₂ O ₃ with smooth appearance and good sphericity The basic properties of the pellets are shown in Table 1.

Example 2

Prepare γ-A ₂ O ₃ pellets according to the steps in Example 1, the difference is: 500 g of sodium alginate solution with a concentration of 2% by weight is added during the batching, and it is fully stirred to form an alginic acid-pseudoboehmite suspension The height of the upper oil phase in the oil-water column is 15cm, and the height of the lower water phase is 104cm; the used drip nozzle aperture size is 3.0mm when dropping the ball, and the properties of the obtained pellets are shown in Table 1.

Example 3

Prepare γ-A ₂ O ₃ pellets according to the steps in Example 1, the difference is: 700 g of sodium alginate solution with a concentration of 0.5% by weight is added during the batching, and the alginate-pseudoboehmite suspension is formed by fully stirring , when dropping the ball, a 1mm drip tip was used, and the properties of the obtained ball are shown in Table 1.

Example 4

γ-A ₂ O ₃ pellets were prepared according to the steps in Example 1, except that the upper oil phase in the oil-water column was kerosene, and the acid treatment time was 50 minutes. The properties of the prepared pellets are shown in Table 1.

Example 5

γ-A ₂ O ₃ pellets were prepared according to the steps in Example 1, except that the upper oil phase in the oil-water column was diesel oil. The properties of the prepared pellets are shown in Table 1.

Example 6

γ-A ₂ O ₃ pellets were prepared according to the steps in Example 1, except that the upper oil phase in the oil-water column was liquid paraffin. The properties of the prepared pellets are shown in Table 1.

Example 7

γ-A ₂ O ₃ pellets were prepared according to the steps in Example 1, except that the water phase in the middle and lower layers of the oil-water column was 0.6 mol/L zinc nitrate solution. The properties of the prepared pellets are shown in Table 1.

Example 8

γ-A ₂ O ₃ pellets were prepared according to the steps in Example 1, except that the water phase in the middle and lower layers of the oil-water column was 0.3 mol/L calcium nitrate solution. The properties of the prepared pellets are shown in Table 1.

Example 9

The gamma-A ₂ O ₃ pellets were prepared according to the procedure in Example 1, except that 5 g of urea was added to the feed solution. The properties of the prepared pellets are shown in Table 1.

Example 10

The gamma-A ₂ O ₃ pellets were prepared according to the procedure in Example 1, except that 10 g of urea was added to the feed liquid. The properties of the prepared pellets are shown in Table 1.

Example 11

The gamma-A ₂ O ₃ pellets were prepared according to the procedure in Example 1, except that 5 g of activated carbon was added to the feed liquid. The properties of the prepared pellets are shown in Table 1.

Comparative example 1

Prepare γ-A ₂ O ₃ pellets according to the steps in Example 1, the difference is that there is only aluminum nitrate solution with a height of 119 cm in the 1.2 m high column

Comparative example 2

The gamma-A ₂ O ₃ pellets were prepared according to the steps in Example 1, except that there was only calcium nitrate solution with a height of 119 cm in the 1.2 m high column.

Table 1

Claims (5)

1. a profit post forming method for ball-aluminium oxide, is characterized in that: join in alginate solution by pseudo-boehmite, expanding agent, stirs and makes Lalgine-pseudo-boehmite suspendible slurry; Suspendible slurry is added dropwise in the profit post by upper oil phase and lower floor's multivalent metal cation salts solution phase composite and forms composite spherical gel particle; Take out gel particle, use acidic solution process; Final drying, roasting obtain ball-aluminium oxide product;

Wherein: described expanding agent is urea, urotropine, Mierocrystalline cellulose or gac, expanding agent add-on is 0 ~ 10% of pseudo-boehmite quality;

Described alginates is one or more in sodium alginate, potassium alginate, Lalgine magnesium, ammonium alginate, and the concentration of alginates is 0.3 ~ 5 heavy %;

The quality of described pseudo-boehmite is 5 ~ 30% of alginate solution quality;

Described multivalent metal cation salts solution is the salts solution of the aluminium of 0.1mol/L ~ saturation concentration, zinc, calcium, copper, iron, ferrous iron, cobalt, manganese or nickel ion;

Described acidic solution hydrogen ion concentration is 0.0001 ~ 2mol/L, and the treatment time is 1 ~ 120 minute.

2., according to method described in claim 1, it is characterized in that described multivalent metal cation salts solution is the aluminium of 0.2 ~ 1mol/L, zinc, calcium, copper or cobalt ion salts solution.

3., according to method described in claim 1, it is characterized in that described oil phase is one or more in kerosene, diesel oil, lubricating oil, heptane, octane, whiteruss, oil phase height 0.1mm ~ 20cm.

4., according to method described in claim 1, it is characterized in that described acidic solution is the salpeter solution of 0.01 ~ 1mol/L, the treatment time is 5 ~ 30 minutes.

5., according to method described in claim 1, it is characterized in that described drying temperature is 80 ~ 120 DEG C, maturing temperature is 450 ~ 800 DEG C.