JPS5827630A - Method and apparatus for reacting powder and gas - Google Patents

Abstract

PURPOSE:To obtain a uniform reaction product, in an apparatus for reacting a powder and a gas, by fixing the powder by a medium having good gas permeability to uniformize the reaction of the powder and the gas. CONSTITUTION:In an apparatus for reacting a powder such as an Si powder and a gas such as a nitrogen containing gas, the powder 2 is fixed in a reaction tube 1 by a medium 2 having gas permeability such as a ceramic fiber 3 or a glass fiber. By this structure, the gas is flowed along the medium 2 and penetrated into the interior of the powder and, therefore, the powder and the gas are uniformly reacted to obtain a uniform reaction product such as Si3N4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for homogenizing reactions between gas and solid phases and an apparatus for carrying out this method.

Conventionally, when obtaining a product by reacting powder and gas, a method has been used in which a boat, crucible, or the like containing the powder is placed in a reaction apparatus and the gas is introduced into one reaction apparatus. For example, when silicon nitride (8+sNJ) is obtained by reacting Si powder with a gas containing nitrogen, a boat 5 filled with 8i powder 2 is placed in a reaction tube 1 as shown in FIG. Nt while heating
A method is used in which gas or NH gas is passed as shown by the arrow to react. However, in this method, the reaction progresses only on the surface of the filled material in the boat that is in contact with the gas, and since it is an exothermic reaction, only the surface portion is sintered, inhibiting the penetration of the gas into the inside of the filled pine, and reducing the nitriding rate. There was a drawback that the yield of αSt and N4 was low. (When reacted at 1300°C for 5 hours.

Nitriding rate: 23%, α5iBN, 65% and β8N,N.

When reacting at 1,350°C for 5 hours, the nitriding rate was 30, αS import was 57, and /8 import was N4.
It was 43 years old. ) On the other hand, the inventor 9 filled the center of the reaction tube 1 with 8i powder 2 as shown in FIG. 2, and filled both ends of the 81 powder with cotton-like ceramic #! The test was conducted by passing N, gas, and NH, gas from one end of the tube while heating the reaction tube by holding it down with a patch 3. However, 8i on the gas inflow side
The powder reacts and generates Si@N4, but it generates heat and S
i, Na solidifies and gas passage is poor, and even if the gas pressure is increased, it does not penetrate into the entire 8i powder.

In the gas absorption reaction of powder near normal temperature,
Conventionally, as shown in Figure 2, a method of filling powder and sending gas from one end of the reaction tube has been used, but as the reaction progresses, the powder absorbs gas and obstructs the passage of JIIL gas. Atsuku.

For example, when NH is absorbed into powder of N IClt.2NH, when the reaction has progressed approximately 2091 times, it becomes difficult for the gas to pass through thereafter, and the reaction stops.

More C! Even in the reaction of absorbing H, O gas into IO or CuSO4.H,O, in the conventional method it was necessary to apply considerable pressure to pass the gas into the tube.

The object of the present invention is to overcome these drawbacks and provide a method and apparatus for reacting powder and gas to obtain a uniform product.

The present invention involves fixing the powder with a continuous air-permeable medium in nine reaction tubes, and introducing a gas into the nine reaction tubes to cause the powder and gas to react! The present invention relates to a method for reacting powder and gas with lf characteristics, and a reactor for reacting powder and gas comprising a reaction tube provided with a continuous air-permeable medium and in which powder is fixed by the medium.

Combinations of powder and gas that can be applied in the present invention include Si powder and gas containing nitrogen, N1CJ, .2NH, powder and NH, gas, and air containing Ca and moisture.

Air containing CaC4 powder and moisture, CuSO4” H*O
Although this invention is generally applied to reactions between powders such as air containing Si powder and gases containing moisture, the present invention is preferable for obtaining St, N by reacting Si powders with gases containing nitrogen at a concentration of 1%. In the reaction, heating may be performed as necessary.

What is a continuous air permeable medium in a reaction tube?

This means that the permeable medium is continuous in the reaction tube. Figures 3, 4, 5 and 7 show a continuous permeable medium in the reaction tube. In the present invention, the powder is fixed by a continuous air-permeable medium.

The media in FIGS. 2 and 6 are not continuous in the reaction tube.

Examples of breathable media include cefmitsu, woven materials,
Porous glass or the like may be used as long as it does not change in quality or suppress the reaction during the reaction between the powder and gas, and the material, shape, diameter of the fiber, length of the fiber, directionality of the fiber, etc. There are no restrictions.

The porosity of the medium filled in the reaction tube is preferably in the range of 80 to 90. This is because if the porosity is too small, gas permeability will be reduced, and if it is too large, powder will enter the pores and obstruct gas flow.

Length 1) and thickness 1 of the powder layer filled in the reaction tube
) is preferably 3 or more.

This is because the larger the ratio of 1/l, the more the gas will penetrate into the powder and the reaction will be more uniform.

Further, the material of the reaction tube used in the present invention may be any material as long as it does not hinder the progress of the reaction, and is not limited to any material, but alumina is preferred from the viewpoint of heat resistance.

The present invention will be explained below with reference to Examples.

Example 1 As shown in FIGS. 3 and 5, the porosity is 851! Si powder of 325 mesh or less with m3 of cotton-like ceramic fiber
P) and filled with an alumina reaction tube IK having an inner diameter of 28 mm, or as shown in FIG. The Si powder 2 filled around the is fixed. The reaction tube filled with Si powder after being heated in this manner was placed in a horizontal electric furnace (not shown), and the reaction tube was heated at 150 d/min of N, gas and 50 d/min.
Nitriding was carried out at a temperature of 1300° C. for 5 hours while passing m/m of sugar gas through the reaction tube.

In FIGS. 3, 4, and 5, 6 is a refractory brick for fixing.

Comparative Example 1 As described above, as shown in FIG. 2, Si powder 2 having the same particle size as in Example 1 was filled in the center of a reaction tube 1 with an inner diameter of 281111 m, and both ends of the Si powder were covered with cotton-like ceramic fibers 3. It was fixed with bricks 6, and N gas and NH gas were passed through it while heating it in the same manner as in Example 1. However, in this case, unlike in Example 1, a gas pressure of 0.06 aim is required.

The results of Example 1 and Comparative Example 1 are shown in Table 1.

The nitridation rate, αS i, N content, and β subtraction, N content were measured using powder X-ray diffraction method.

Happy 1 Table 1I! I! From Example 1, the nitriding rate and αSi,
It is shown that silicon nitride with a high N4 content can be obtained.

Comparative Example 2 NiClt.2NH of 325 mesh or less in the longitudinal direction of a glass reaction tube 1' having an inner diameter of 28 mm as shown in FIG.

Powder 2' (αIgmol) and cotton-like glass fibers 3' were alternately filled, and the 9-order formula of NH and de-NH was repeated.

Ni C1@・2 NH, + 4 NH, 5Ni Cj
,・6NH.

Both the reaction rate and reaction rate were high for the first one or two times, but as the powder expanded due to repeated NH, reaction, fine powder was mixed into the glass fibers, and both the reaction rate and reaction rate gradually decreased. did. Additionally, due to the structure of this device, there is NH in the reaction tube.
, a pressure of 1 to 2 atm is required to pass the gas. In FIG. 6, 7 is a rubber stopper.

Example 2 As shown in FIG. 7, a glass reaction tube 1' with an inner diameter of 28 cm was prepared.
A gas flow body 4 with a diameter of about &0 cm obtained by intertwining stainless steel wires with a diameter of 34 μm arranged continuously so that the porosity is 905 G in the core of the inside, makes the gas flow. body 4
325 filled to be around VCII/l-6
NiC1, 2 NH, powder 2' (0,
18 mol) was fixed, and both ends of the powder 2' were held down with the same gas flow body 4 and rubber stopper 7.

(A) NH, 1.0 per minute! NH was converted into NH by flowing it into the reaction tube for 45 minutes at a flow rate of .

(B) Next, NH was removed at 250° C. for 180 minutes while introducing dry air at a flow rate of 0.21 per minute.

This operation of NH and Bl was repeated 10 times. The NH conversion rate for each repetition showed little variation as shown in Table 2.

Table 2 Example 3 NiC11.2 NH of Example 2, 325
Fill with 0.38 tnol of CaO powder below mesh size.

As a result of flowing air containing cH and O instead of NH and gas at room temperature at a flow rate of 360° per minute, the production rate of Ca(OH) was 81.81 after 21 hours.

NH, gas substitute F) I/CH, air containing O was flowed at the same flow rate as in the example. However, since almost no flow occurred when no pressure was applied, a pressure of Q, 12 atm was applied, and after 21 hours, 7G, 9-00a (OH) was produced.

Example 4 In place of the CaO powder in Example 3, 53 mol of CaCj of 325 mc2 or less and powder Q were filled, and air containing HIO was flowed at a flow rate of 360 -/min.

The amount of H and O absorbed reached 0.89 mol after 18 hours.

Comparative Example 4 The same Ca as in Example 4 was used instead of the CaO powder in Comparative Example 3.
It was filled with C1m powder and air containing H80 was flowed at the same flow rate. However, the amount of absorption will not be the same unless the air pressure is increased as the absorption progresses.

The differential pressure after 18 hours to obtain the same amount of absorption is 0.24 atm
Met.

Example 5 An average of 100 mesh was used as a substitute for CaO powder in Example 3.
Filled with 0.32d of Cu SO,-H,0 powder,
Air containing lo was passed through at a flow rate of 360 d/min.

The rate of absorbing H and O to produce Cu804.5H,0 was 221 after 20 hours.

Comparative Example 5 The same Cu as in Example 5 was used instead of CaO powder in Comparative Example 3.
804・H! 0 and air containing H,0 was passed through at the same flow rate. However, unless the air pressure is increased as the absorption of H and O progresses, the amount of absorption at the same rate will not be achieved. In this case, the differential pressure is 0.062 atm after 20 hours.

According to the method for reacting powder and gas according to the present invention.

Since the gas can easily pass through the reaction tube, there is almost no need to apply gas pressure, and the gas can penetrate well into the powder, resulting in good reaction uniformity.

Furthermore, according to the powder-gas reaction device of the present invention, the gas flows along a medium with good air permeability such as ceramic fibers, and the powder in contact with the flow path is cooled by the gas fluid. It has the effect of preventing solidification of the product.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, FIG. 2, and FIG. 6 are cross-sectional views showing a conventional method and apparatus for reacting powder and gas, and FIG. 4, 'M5 and 7 are sectional views showing a method and apparatus for reacting powder and gas according to an embodiment of the present invention. Explanation of symbols 1.1'...Reaction tube 2.2'...Powder 3
...Ceramic fiber m3'...Glass fiber 4...Gas flow medium 5...Boat 6...Refractory brick
7...Gomu Orange Agent Patent Attorney Kunihiko Wakabayashi II2] No. 27 No. 37
Figure 4 Figure 5

Claims (1)

[Claims] 1. Powder, which is characterized by fixing the powder with a continuous air-permeable medium in a reaction tube, and introducing gas into the reaction tube to cause the powder and gas to react. How gases react. 2. The method for reacting powder and gas according to claim 1, wherein the powder is 84 powder and the gas is a nitrogen-containing gas. & Powder is N1CJt・2NH, powder is N1CJt・2NH, gas is N
A method for reacting a powder with a gas according to claim 1, which is H1l gas. Table 1. The powder fixed in the reaction tube is a powder having a ratio of the length A') of the packed bed of powder to the thickness 1) of 3 or more. Method of reaction between powder and gas. A powder and gas reaction apparatus comprising a reaction tube in which a continuous air-permeable medium is provided and powder is fixed by the medium. The powder-gas reaction device according to claim 5, wherein the medium having air permeability has a porosity of 80 to 9,091.