CN104148118B - A kind of method of utilizing the reactive halide of water to prepare modified aluminium oxide supports - Google Patents

Abstract

The invention discloses a kind of reactive halide of water that utilizes and process the method that boehmite is prepared modified aluminas, method comprises: in the process of boehmite temperature-programmed calcination, adopt the mode of inert gas bubbling, pass into volume fraction be 0.1 ~ 30% water reaction halide and the water mutual effect of boehmite roasting generation, then after drying, roasting, prepare the controlled modified aluminas of pore-size distribution and surface nature. The inventive method technique is simple, with low cost, can realize the controlled modulation of the distribution of aluminium oxide aperture and surface nature simultaneously, and realistic Production requirement, has broad application prospects in field of material preparation.

Description

A method for preparing modified alumina carrier by using water-reactive halide

technical field

The invention belongs to the technical field of material preparation, and in particular relates to a method for preparing modified alumina with concentrated pore size distribution by utilizing water-reactive halides.

Background technique

Porous supports are widely used in high-tech fields such as adsorption, catalysis, separation and microelectronics. The pore size distribution of the porous carrier is a key factor affecting the diffusion of the medium in the pores. In the field of catalytic materials, it has an important impact on the activity, selectivity and thermal stability of the catalyst, and also has an important impact on the separation performance of separation materials such as adsorbents. Therefore, developing an efficient, stable, and simple method for regulating the pore size distribution is a core challenge in this field.

The pore size distribution adjustment in the carrier synthesis and molding stages is mainly realized by adjusting the size and packing mode of the pore-forming particles. The pore size distribution can be adjusted by adding suitable templates and/or adjusting suitable preparation conditions, but these methods have Its disadvantages cannot be ignored, such as high synthesis cost, serious pollution of template agent, and it is not easy to realize large-scale industrial production. The pore size distribution of the formed carrier can be adjusted by appropriate chemical treatment (acid treatment, alkali treatment, water vapor treatment, etc.), hydrothermal treatment and other post-treatment methods, but these methods will cause certain damage to the structure of the carrier itself. For example, the crushing strength is reduced, and there are problems to be solved urgently such as the generation of a large amount of waste water, the complicated mechanism of action, and the difficulty of industrialization (D.L.Trimm, et al., Appliedcatalysis, 1986, 21(2), 215-238.).

Water-reactive halides can react with water and/or hydroxyl groups to form corresponding oxides (or hydroxides). The chemical vapor deposition reaction of water vapor and water-reactive halides has been used to modify porous membrane materials, and certain achievements have been made. Progress (M.Niwa, et al., Journal of Physics and Chemistry of Solids, 1989,50(5):487-496.), but this method usually needs to be carried out under vacuum conditions, and there are problems such as difficult control of the amount of water vapor, which is difficult Realize the controllable modulation of the pore structure properties and surface properties of the porous carrier. Some progress has been made in surface modification of porous supports by using high-temperature reactions (higher than 300°C) between water-reactive halides and porous supports such as molecular sieves (M.W.Anderson, et al., Zeolites, 1986, 6 (6 ):455-466.), but the reaction at high temperature will lead to serious damage to the framework of the porous support, such as dealumination, etc., and it is difficult to achieve controllable modulation of the pore structure and surface properties of the porous support. Utilize the reaction of water generated during the roasting process of water-reactive halides (silicon tetrachloride, titanium tetrachloride, etc.) A method for simultaneously realizing the modulation of the pore size distribution and surface properties of porous alumina supports has not been reported.

Contents of the invention

The object of the present invention is to provide a method for preparing modified alumina with concentrated pore size distribution. The method provided by the invention can utilize water-reactive halides (such as silicon tetrachloride, which is a by-product of the polysilicon industry) in industry, and has low cost, simple process, little pollution, and easy industrialization. At the same time, the control of the surface properties of porous supports can be achieved, which has broad application prospects.

In order to achieve the above object, the present invention adopts the following technical scheme: a preparation method of modified alumina with concentrated pore size distribution is formed by utilizing water-reactive halides and adsorbed water on the surface and channels of alumina carrier precursors and roasting decomposition Water reacts to generate corresponding nano-scale solid oxides, thereby covering, blocking, and modulating the pore size distribution and surface properties of the porous alumina carrier. Described method comprises the following steps:

(1) Load the alumina carrier precursor in the reactor, and purge with dry inert gas at room temperature~50℃ for 0.5~24h, and the space velocity of the inert gas is 100~10000h ^-1 ;

(2) Use an inert gas with a space velocity of 100~10000h ^-1 as the purge gas, the reactor pressure is 0.1~0.3MPa (absolute pressure), and the reactor is heated at a heating rate of 2~10°C/min. When the reaction When the temperature of the bubbler rises to 40~100°C, inert gas bubbles are used to carry water-reactive halides to interact with the precursor of the alumina carrier. The temperature of the bubbler is 30~150°C, and the space velocity of the inert gas is 100~1000h ^-1 ; when the temperature of the reactor rises to 110~170°C, switch to dry inert gas for purging; when the temperature of the reactor rises to 350~650°C, stop heating and roast at 350~650°C for 2 After ~8h, cool to room temperature to obtain a porous alumina carrier with concentrated pore size distribution.

The inert gas is one or more of nitrogen, helium and argon.

Preferably, the alumina carrier precursor is one or more of pseudoboehmite, boehmite, and gibbsite.

Preferably, the water-reactive halide is one of silicon tetrachloride, titanium tetrachloride, tin tetrachloride and germanium tetrachloride.

Preferably, the inert gas is one or more of nitrogen and argon.

Preferably, the reactor is one of a corrosion-resistant fixed-bed reactor and a corrosion-resistant fluidized-bed reactor.

Preferably, in the step (1), the purging temperature is room temperature, and the purging time is 0.2-0.3h.

Preferably, in the steps (1) and (2), the space velocity of the inert gas is 200~400h ^-1 .

Preferably, in the step (2), the pressure of the reactor is 0.1-0.2 MPa.

Preferably, in the step (2), the heating rate of the reactor is 2-5° C./min.

Preferably, in the step (2), the temperature of the bubbler is 35-100°C, the temperature for starting the bubbling is 50-90°C, and the temperature for stopping the bubbling is 120-150°C.

Preferably, in the step (2), the calcination temperature is 450-550° C., and the calcination time is 4-6 hours.

The modified alumina is an oxide/alumina composite carrier with concentrated pore size distribution, and the oxide is one or more composite oxides of silicon oxide, titanium oxide, tin oxide, and germanium oxide.

Significant advantage of the present invention is:

(1) For the first time, the present invention utilizes water-reactive halides to react with water generated during the roasting process of alumina carrier precursors to prepare modified alumina, and the operation process is simple.

(2) The present invention can utilize industrial by-products of water-reactive halides (such as silicon tetrachloride, which is a by-product of the polysilicon industry), with low cost, meets actual production needs, and is easy to popularize and apply on a large scale.

(3) The present invention does not destroy the main structure of the porous carrier.

(4) The controllable introduction of metal and/or non-metal oxides can control the surface properties of porous supports while regulating the pore size distribution.

(5) The porous carrier prepared by the method of the present invention has less pore volume with a pore size distribution of less than 4 nm, concentrated in 4-10 nm, and is suitable for preparing catalyst carriers, adsorbent carriers, etc. in the medium mesopore range.

detailed description

The method for regulating the pore size distribution of the porous carrier according to the present invention will be further described through specific examples below.

Example 1: Fill 0.5kg of pseudo-boehmite (produced by Aluminum Corporation of China Shandong Branch, P-DF-03, ignition loss ≤ 24%) in a glass-lined fixed-bed reactor, and use dry nitrogen at 40°C Under purge for 0.2h, the space velocity of nitrogen is 300h ^-1 ; dry nitrogen is used as purge gas, the reactor pressure is 0.1MPa (absolute pressure), and the temperature of the fixed bed reactor is raised at a rate of 2°C/min. When the temperature of the reactor rises to 50°C, nitrogen bubbles are used to carry the water-reactive halide silicon tetrachloride to interact with pseudo-boehmite. The temperature of the bubbler is 35°C, and the space velocity of nitrogen is 300h ^-1 ; when the reactor temperature rises to 120°C, switch to dry nitrogen for purging; when the reactor temperature rises to 450°C, stop heating, and after roasting at 450°C for 5h, cool to room temperature to obtain a concentrated pore size The distributed porous alumina carrier, its pore structure parameters are shown in Table 1.

Example 2: Fill 0.5kg boehmite (manufactured by Zibo Baida Chemical Co., Ltd., BD-BS03, alumina content ≥ 83%) into a glass-lined fixed-bed reactor, blow with dry nitrogen at 35°C Sweep for 0.5h, the space velocity of nitrogen is 400h ^-1 ; dry nitrogen is used as the sweeping gas, the reactor pressure is 0.12MPa (absolute pressure), the temperature of the fixed bed reactor is raised at a rate of 4°C/min, when the reaction When the temperature of the bubbler rises to 60°C, nitrogen bubbles are used to carry the water-reactive halide titanium tetrachloride to interact with boehmite. The temperature of the bubbler is 35°C, and the space velocity of nitrogen is 400h ^-1 ; When the temperature of the reactor rises to 130°C, switch to dry nitrogen for purging; when the temperature of the reactor rises to 550°C, stop the temperature rise, and after calcination at 350°C for 8 hours, cool to room temperature to obtain porous oxide with concentrated pore size distribution. Aluminum carrier, its pore structure parameters are shown in Table 1.

Example 3: Pack 0.5kg of boehmite (manufactured by Zibo Baida Chemical Co., Ltd., BD-BS03, with alumina content ≥ 83%) in a glass-lined fixed-bed reactor, and purge with dry nitrogen at 40°C 0.5h, the space velocity of nitrogen is 300h ^-1 ; dry nitrogen is used as the purge gas, the reactor pressure is 0.15MPa (absolute pressure), the temperature of the fixed bed reactor is raised at a rate of 10°C/min, when the reactor When the temperature rises to 50°C, the water-reactive halide tin tetrachloride interacts with boehmite in the form of nitrogen bubbling, the temperature of the bubbler is 50°C, and the space velocity of nitrogen is 600h ^-1 ; when the reaction When the temperature of the reactor rises to 150°C, switch to dry nitrogen for purging; when the temperature of the reactor rises to 550°C, stop heating up, and after calcination at 550°C for 4 hours, cool to room temperature to obtain porous alumina with concentrated pore size distribution The carrier, its pore structure parameters are shown in Table 1.

Example 4: Pack 0.5 kg of gibbsite (manufactured by Zibo Yaohe Aluminum Co., Ltd., HP, with an Al content of 64.5%) in a glass-lined fixed-bed reactor, and purge 0.5 kg with dry nitrogen at 40 ° C. h, the space velocity of nitrogen is 500h ^-1 ; dry nitrogen is used as the purge gas, the reactor pressure is 0.2MPa (absolute pressure), and the fixed bed reactor is heated at a heating rate of 4°C/min. When the reactor temperature When the temperature rises to 60°C, the water-reactive halide germanium tetrachloride is carried to interact with gibbsite by nitrogen bubbling, the temperature of the bubbler is 35°C, and the space velocity of nitrogen is 400h ^-1 ; when the reaction When the temperature of the reactor rises to 150°C, switch to dry nitrogen for purging; when the temperature of the reactor rises to 650°C, stop heating up, and after calcination at 550°C for 8 hours, cool to room temperature to obtain porous alumina with concentrated pore size distribution The carrier, its pore structure parameters are shown in Table 1.

Example 5: Fill 0.5kg of pseudo-boehmite (produced by Aluminum Corporation of China Shandong Branch, P-DF-03, ignition loss ≤ 24%) in a glass-lined fixed-bed reactor, and use dry nitrogen at 45°C Purge down for 0.2h, the space velocity of nitrogen is 300h ^-1 ; dry nitrogen is used as purge gas, the reactor pressure is 0.25MPa (absolute pressure), and the temperature of the fixed bed reactor is raised at a rate of 5°C/min. When the temperature of the reactor rises to 50°C, the water-reactive halide titanium tetrachloride interacts with the pseudo-boehmite by nitrogen bubbling, the temperature of the bubbler is 45°C, and the space velocity of nitrogen is 300h ^-1 ; when the reactor temperature rises to 120°C, switch to dry nitrogen for purging; when the reactor temperature rises to 500°C, stop heating, and after roasting at 650°C for 2h, cool to room temperature to obtain a concentrated pore size The distributed porous alumina carrier, its pore structure parameters are shown in Table 1.

Example 6: Fill 0.5kg of pseudo-boehmite (produced by Aluminum Corporation of China Shandong Branch, P-DF-03, ignition loss ≤ 24%) in a corrosion-resistant fluidized bed reactor, and use dry nitrogen Fluidized treatment at 35°C for 0.5h, nitrogen space velocity is 5000h ^-1 ; dry helium is used as purge gas, reactor pressure is 0.3MPa (absolute pressure), fluidized bed reactor is 8°C/ The temperature was raised at a heating rate of min. When the temperature of the reactor rose to 50°C, nitrogen bubbles were used to carry the water-reactive halide silicon tetrachloride to interact with pseudo-boehmite, and the temperature of the bubbler was 30°C. , the space velocity of nitrogen is 8000h ^-1 ; when the temperature of the reactor rises to 150°C, switch to dry nitrogen for purging; , and cooled to room temperature to prepare a porous alumina carrier with concentrated pore size distribution, and its pore structure parameters are shown in Table 1.

Comparative example 1: Fill 0.5kg of pseudo-boehmite (produced by Aluminum Corporation of China Shandong Branch, P-DF-03, ignition loss ≤ 24%) in a fixed-bed reactor, and blow it with dry nitrogen at 40°C Sweep for 0.2h, the space velocity of nitrogen is 300h ^-1 ; dry nitrogen is used as the sweeping gas, the reactor pressure is 0.1MPa (absolute pressure), and the temperature of the fixed bed reactor is raised to 450°C at a heating rate of 2°C/min , and kept at 450°C for 4h, and then cooled to room temperature. The pore structure parameters of the prepared alumina carrier are shown in Table 1.

The above-mentioned embodiments are only several implementation modes of the present invention, and the descriptions are more specific and detailed, but should not be construed as limiting the patent scope of the present invention. All chemicals used are commercially available. It should be noted that for those skilled in the art, some improvements can be made on the basis of the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention shall be determined by the appended claims.

Table 1 Pore structure parameters of alumina support

The above examples illustrate that the modified alumina prepared by the method of the present invention has a concentrated pore size distribution, the pore volume below 4nm is less, and the pore volume distributed in the range of 4-10nm accounts for more than 70% of the total pore volume, which is comparable to Compared with the comparative example, the method has obvious improvement, and the operation process is simple, and can be applied to the modulation process of the pore structure and surface properties of porous carriers such as alumina, silicon oxide and molecular sieve.

Claims (5)

1. a preparation method for modified aluminas, is characterized in that, comprises the following steps: (1) is by alumina support predecessorBe seated in reactor, with dry inert gas, at room temperature～50 DEG C, purge 0.5～24h, the air speed of inert gas is100～10000h^-1; (2) taking air speed as 100～10000h^-1Inert gas be sweep gas, reactor absolute pressure is 0.1～0.3MPa, reactor heats up with the heating rate of 2～10 DEG C/min, in the time that temperature of reactor rises to 40～100 DEG C, with lazyProperty gas sparging mode, carry one in the reactive halide silicon tetrachloride of water, titanium tetrachloride, butter of tin, germanium tetrachlorideKind interact with alumina support predecessor, bubbler temperature is 30～150 DEG C, the air speed of inert gas is 100～1000h^-1; In the time that temperature of reactor rises to 110～170 DEG C, switch dry inert gas and purge; When temperature of reactor literDuring to 350～650 DEG C, stop heating up, at 350～650 DEG C, after roasting 2～8h, be cooled to room temperature, make aperture and concentrate distributionPorous alumina carrier.

2. the preparation method of modified aluminas according to claim 1, is characterized in that, described alumina support predecessorFor one or more in boehmite, boehmite, gibbsite.

3. the preparation method of modified aluminas according to claim 1, is characterized in that, described inert gas is heliumOne or more in gas, argon gas.

4. the preparation method of modified aluminas according to claim 1, is characterized in that, described reactor is corrosion-resistantOne in fixed bed reactors, corrosion-resistant fluidized-bed reactor.

5. the preparation method of modified aluminas according to claim 1, is characterized in that, described modified aluminas is holeOxide/the alumina composite carrier distributing is concentrated in footpath, and described oxide is in silica, titanium oxide, tin oxide, germanium oxideOne.