CN104353504A - Preparing method of spherical titanium-aluminum composite carrier - Google Patents

Abstract

The invention is a preparation method of a spherical titanium-aluminum composite carrier, which is characterized in that: adding deionized water and titanium dioxide to the aluminum glue and mixing uniformly; slowly adding alginate solution, and stirring at a high speed to form a suspension slurry; The slurry is dropped into the polyvalent metal cation solution to form spherical composite gel particles; the gel particles are taken out, dried and calcined to obtain a spherical titanium-aluminum composite carrier; wherein: the aluminum gel is alumina hydrogel or nano-alumina sol The amount of titanium dioxide added is 0.1 to 4 times the mass of aluminum sol in terms of Al ₂ O ₃ , and the crystal phase of titanium dioxide is selected as anatase phase; the weight solid content in the suspension slurry is 5 to 25% , Alginate weight content is 0.3～5%; Described alginate is one or more in sodium alginate, potassium alginate, magnesium alginate, ammonium alginate; Described polyvalent metal cation solution is 0.1 Salt solution of aluminum, zinc, calcium, copper, iron, ferrous, cobalt, manganese or nickel ions with mol/L～saturated concentration.

Description

A kind of preparation method of spherical titanium-aluminum composite carrier

technical field

The invention relates to the technical field of catalyst carriers, in particular to a method for preparing a spherical titanium-aluminum composite carrier.

technical background

Since the 1970s, _TiO2 has attracted much attention as a new type of catalytic material with unique properties. As a carrier, TiO ₂ has a strong interaction with the active components, which can change the adsorption and catalytic performance of the catalyst, and it has good photocatalytic performance, anti-coking and anti-poisoning capabilities. However, due to the few pores on the surface of TiO ₂ , the specific surface area is lower than that of other commonly used metal oxide supports, so that the amount of single-layer dispersed active components that can be loaded on TiO ₂ is very small; at the same time, its surface shrinks easily when heated, and it is easy to get from The anatase phase changes into a low-activity rutile phase; in addition, _TiO2 is not easy to form, and it is not suitable for direct use as a carrier in industry. Therefore, it is necessary to find a material that can support the high activity of TiO ₂ and has a large specific surface area, uniform pore structure, easy molding, and high mechanical strength to make up for the structural deficiency of TiO ₂ .

The introduction of Al ₂ O ₃ into TiO ₂ can produce a catalyst support with a higher specific surface area, and the presence of Al ₂ O ₃ will affect the electronic environment of Ti, thereby changing the chemical state of the catalyst surface atoms. Compared with conventional Al ₂ O ₃ , SiO ₂ and other supports, when TiO ₂ -Al ₂ O ₃ complex oxide is used as a catalyst support, it has many unique physical and chemical properties. It has been widely used in reactions such as ammonia, so it is favored by many researchers.

CN103861660A discloses a rolling forming method of a spherical titanium-aluminum composite oxide. The steps of the method are as follows: 1) Titanium dioxide with a particle size of 100-400 mesh and quick-release powder are mixed according to the mass ratio of 1:3-1:1. Fully mix in a three-dimensional mixer; 2) Add the above-mentioned mixed powder into a sugar coating machine, add a binder during the rolling process for rolling molding, and take it out when the particles with a diameter of 1.8-5mm are formed, and the amount of the binder is mixing 30-80% of the mass of the powder; 3) The spherical TiO ₂ -Al ₂ O ₃ composite oxide is obtained by curing, drying and roasting the shaped particles obtained in step 2). The method of the invention is simple, but the dust in the preparation process is large, the pore volume of the product is small, and the heap ratio is large.

CN103861658A discloses a method for preparing a spherical titanium-aluminum composite oxide carrier, which is characterized in that: firstly, titanium oxide and aluminum oxide powders are fully mixed, and then the mixed powder is added in batches to soluble seaweed with a mass concentration of 0.5-3.5%. In the aqueous salt solution, after stirring and homogenizing, the obtained titanium oxide-alumina-alginate suspension is dropped into the aqueous solution of calcium nitrate to gel to form titanium oxide-alumina-calcium alginate composite pellets; then The composite pellet is prepared by immersing the composite pellet into an aqueous solution containing acetic acid and chitosan to further coat and cross-link, and finally washing, drying and roasting. The method of the invention is simple and easy, with mild conditions, low energy consumption and less discharge of waste water and waste gas. The prepared spherical titanium-aluminum carrier has the characteristics of large-scale adjustment of titanium-aluminum ratio, smooth surface, high strength and low wear. However, titanium oxide and aluminum oxide are mixed powders, which are difficult to disperse uniformly, which is not conducive to giving full play to the performance of the two. After molding, a coating cross-linking reaction is required, which will cause the migration of internal aluminum oxide, resulting in the oxidation of the ball from the inside to the outside. The content of titanium is gradually reduced.

Contents of the invention

The purpose of the present invention is to provide a low-cost, high-efficiency and environmentally friendly preparation method of spherical titanium-aluminum composite carrier.

The invention is a preparation method of a spherical titanium-aluminum composite carrier; it is characterized in that: adding deionized water and titanium dioxide to the aluminum glue and mixing uniformly; slowly adding alginate solution, and stirring at a high speed to form a suspension slurry; Dropping the slurry into the polyvalent metal cation salt solution to form spherical composite gel particles; taking out the gel particles, drying and roasting to obtain spherical titanium-aluminum composite carriers;

Wherein: the aluminum gel is alumina hydrogel or nano-alumina sol; the alumina hydrogel is preferably made of alkali metal aluminate and acid reaction, aluminum salt or acidic aluminum sol and alkali reaction, aluminum amalgam Amorphous gels prepared by hydrolysis or aluminum alkoxide hydrolysis;

The amount of titanium dioxide added is 0.1 to 4 times the mass of aluminum sol calculated by Al ₂ O ₃ , and the crystal phase of titanium dioxide is selected as anatase phase;

The weight solid content in the suspension slurry is 5-25%, and the weight content of alginate is 0.3-5%;

The alginate is one or more of sodium alginate, potassium alginate, magnesium alginate, ammonium alginate;

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 or copper ion salt solution.

In the above technical solution, the drying temperature is preferably 80-120°C, and the calcination temperature is preferably 450-600°C.

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

①Using aluminum glue as the aluminum source, the water column molding method is used for molding. Since the aluminum glue itself has good bonding performance, the gel particles after molding do not need to be subjected to the acid treatment step commonly used in the existing water column process, and can be directly dried , Roasting, greatly shorten the production process steps, easy to realize industrial continuous production;

②Adding titanium dioxide with stable skeleton and acid insensitivity to alumina sol can not only maintain the original structure and properties of titanium dioxide, but also play a role of support and pore expansion, reducing the shrinkage of gel beads during the drying process, The product has high strength, large pore volume and small stack ratio;

③Alumina sol and titanium dioxide are mixed to ensure full contact and mixing of the two, which is beneficial to the dispersion of titanium dioxide and improves the activity of titanium dioxide;

Detailed ways

The preparation method of the spherical titanium-aluminum composite carrier of the present invention will be further described below in conjunction with specific examples, but the present invention is not limited thereby.

Example 1

At room temperature, use 15% nitric acid as the bottom liquid, gradually add sodium metaaluminate solution with a solid content of 10-20% by weight based on alumina for reaction under stirring, control the pH at the end point to 6-8.5, and directly carry out plate and frame filtration after the reaction and removing impurities to obtain an alumina hydrogel with a dry basis content of 15-30% by weight.

Example 2

Take 500g of alumina hydrogel with a dry basis content of 20% prepared according to Example 1; add 20g of anatase titanium dioxide and stir evenly; then slowly add 400g of sodium alginate solution with a concentration of 2% by weight and stir at a high speed to prepare Suspension slurry; drop the suspension slurry into an aluminum nitrate solution with an aluminum ion concentration of 1mol/L to form composite gel particles; take out the gel particles, dry at 120°C for 10 hours, and then bake at 550°C for 4 hours to obtain a spherical shape Titanium-aluminum composite carrier.

Analyze and characterize the product: particle size: 2.0±0.05mm; average strength: 90N/particle; pore volume: 0.85ml/g; specific surface area: 250m ² /g.

Example 3

Take 500 g of alumina hydrogel with a dry basis content of 20% prepared according to Example 1; add 100 g of anatase titanium dioxide, 600 g of sodium alginate solution with a concentration of 3% by weight, and stir at a high speed to uniformly make a suspension slurry; Drop the suspension into an aluminum nitrate solution with an aluminum ion molar concentration of 0.5 mol/L to form composite gel particles; take out the gel particles, dry them at 120°C for 10 hours, and then bake them at 550°C for 4 hours to obtain spherical titanium-aluminum composites. carrier.

Analyze and characterize the product: particle size: 2.15±0.05mm; average strength: 55N/particle; pore volume: 0.65ml/g; specific surface area: 215m ² /g.

Example 4

Take 500 g of alumina hydrogel with a dry basis content of 20% prepared according to Example 1; add 300 g of anatase titanium dioxide and 900 g of a 3% by weight sodium alginate solution, and stir at a high speed to uniformly prepare a suspension; Drop the suspension into an aluminum nitrate solution with an aluminum ion molar concentration of 0.5 mol/L to form composite gel particles; take out the gel particles, dry them at 120°C for 10 hours, and then bake them at 550°C for 4 hours to obtain spherical titanium-aluminum composites. carrier.

Analyze and characterize the product: particle size: 1.95±0.05mm; average strength: 35N/particle; pore volume: 0.42ml/g; specific surface area: 180m ² /g.

Example 5

Take 300g of nano-alumina sol (produced by Hangzhou Wanjing New Material Co., Ltd., model JR14W-1, with an alumina content of 30%); add 100g of anatase titanium dioxide and 100g of deionized water and stir evenly; add 300g of seaweed with a concentration of 4% by weight sodium nitrate solution, stirred evenly to make a suspension slurry; the suspension slurry was dropped into an aluminum nitrate solution with an aluminum ion molar concentration of 0.5mol/L to form composite gel particles; the gel particles were taken out and dried at 120°C for 10 hours, and then calcined at 550°C for 4 hours to obtain a spherical titanium-aluminum composite carrier.

Analyze and characterize the product: particle size: 2.0±0.05mm; average strength: 55N/particle; pore volume: 0.75ml/g; specific surface area: 240m ² /g.

Claims (4)

1. the preparation method of a spherical titanium aluminium complex carrier; It is characterized in that: in aluminium glue, add deionized water, titanium dioxide mixes; Slowly add alginate solution, high-speed stirred makes suspendible slurry; Spherical composite gel particle is formed by suspendible slurry instillation multivalent metal cation solution; Take out gel particle, carry out drying, roasting obtains spherical titanium aluminium complex carrier;

Wherein: described aluminium glue is alumina hydrogel or nano alumina sol;

The addition of described titanium dioxide is with Al ₂o ₃0.1 ~ 4 times of Alumina gel quality of meter, the crystalline phase of titanium dioxide elects Anatase as;

In described suspendible slurry, weight solid content is 5 ~ 25%, alginate weight content is 0.3 ~ 5%;

Described alginate is one or more in sodium alginate, potassium alginate, alginic acid magnesium, ammonium alginate;

Described multivalent metal cation solution is the salting liquid of the aluminium of 0.1mol/L ~ saturated concentration, zinc, calcium, copper, iron, ferrous iron, cobalt, manganese or nickel ion.

2., according to method described in claim 1, it is characterized in that described alumina hydrogel is the unformed gel prepared with acid reaction, aluminium salt or acidic aluminum sol and alkali reaction, aluminium amalgam hydrolysis or aluminium alcoholates hydrolysis by alkali metal aluminate.

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

4., according to method described in claim 1, it is characterized in that described baking temperature is 80 ~ 120 DEG C, sintering temperature is 450 ~ 600 DEG C.