JPS58171480A - Catalytic gasification of coal - Google Patents

Abstract

PURPOSE:To accelerate the gasification of coal, and to improve the conversion of the reaction at a temperature lower than the conventional gasification temperature, by reacting coal with CO2 and steam at high temperature in the presence of a catalyst composed of lead or tin. CONSTITUTION:(A) Coal or a carbonized product (preferably having a particle diameter of 0.01-0.05mm.) is gasified by reacting with (B) CO2 and/or steam preferably at a high temperature above 850 deg.C and below 900-950 deg.C in the presence of (C) lead or tin. The amount of the catalyst (C) is preferably 0.01-0.02atom of the catalyst metal per 1atom of carbon in the component (A), and the amount of the component (B) is 1-2mol per 1mol of carbon atom in the component (A). The reaction is preferably carried out under normal pressure -10kg/cm<2>G. EFFECT:Advantageous in view of the material and the thermal efficiency of the gasification furnace.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for catalytic gasification of coal or its carbides.

Methods of gasifying coal by reacting it with steam, oxygen-containing gas, hydrogen, carbon dioxide, or a mixture thereof have been practiced for a long time, and various methods have been proposed. However, these methods require high temperatures of 900 to 100[theta]C or higher, and the gasification rate of coal is not necessarily sufficient.C) None. At the same time as increasing the reaction rate, studies are also progressing on catalytic gasification of coal for the purpose of desulfurization and denitrification.
)1''], and alkali metals and some transition metals are known to increase the reaction rate of coal with steam, hydrogen or air.However, these catalysts still require improvement in terms of activity. There is still room for this, and a catalyst with even higher activity is desired.

As a result of our search for a highly active catalyst for catalytic gasification of coal with carbon dioxide and/or steam, the present inventors found that
The present invention was completed by discovering that lead and tin significantly accelerate the gasification rate at high temperatures of goθ°C or higher.

The catalytic gasification method of coals of the present invention is characterized by gasifying coal or carbide by reacting it with carbon dioxide and/or water vapor at high temperature in the presence of lead or tin.

A wide variety of coals can be used in the present invention, including low-grade coals such as lignite. Also, carbide of coal can be used similarly. Furthermore, carbides of substances other than coal can also be used. The particle size of the coal supplied to the gasification process can vary widely depending on the gasification method employed, but is preferably a particle size of θ/n or less, particularly preferably a particle size of θ0/~0.0! ;ran.

The amount of catalyst present is the catalyst metal θ per carbon/atom in raw coal.
00/~o, o s atoms, especially 0. It is preferable that it is O/~0.02 atoms. The catalyst may be added as an oxide or as a mineral acid salt such as a sulfate;
Further, it may be added as an acid salt such as acetate or oxalate, or it may be added to raw coal as metal powder. The catalyst can be added by mixing raw material coal with the above catalyst precursor or catalyst in solid form, impregnating coal with a solution or suspension of the catalyst precursor, or using Catalyst R? A solid or aqueous solution of the J precursor is treated with carbon dioxide and/or
Alternatively, depending on the gasification method employed, a method such as blowing it together with steam and making it adhere to the coal can be used.

The gasifying agents carbon dioxide and water vapor are added alone or in combination. The mixing ratio is determined depending on the composition of the first gas, but for example, if the Co,/'H20 molar ratio is 0.
A range of 7 to IO is used. These gasifying agents are
Additionally, it can be used with appropriate amounts of hydrogen or oxygen-containing gases. The amount of these gases is determined to be the amount necessary to maintain the reaction temperature. The amount of carbon dioxide or water vapor is preferably 7 to 2 moles or 7 to 2 moles, respectively, per mole of carbon in the raw coal.

The reaction pressure is preferably normal pressure to /OkYcrla.

The reaction temperature is the temperature at which the catalyst, lead or tin, becomes metallic.
The temperature is preferably oθ°C or higher, particularly 330°C or higher. The upper limit of the reaction temperature is limited by the reactor material, etc., but is preferably 900~q! ;o℃. The gasification rate increases significantly at the above reaction temperature, but this is because lead or tin is in a metal state and molten at a high temperature of gOO℃ or higher, and the surface tension of the molten metal is small. This may be due to good contact between the coal and the catalyst under the reaction conditions.

As the reaction method, various methods such as fixed bed, fluidized bed, transport bed, and molten bed are used. Further, any of a continuous type, a discontinuous type, an internal heating type, and an external heating type can be used. Preferably, a continuous internal heating type is used.

Lead or tin used as a catalyst is discharged together with ash from the gasification stage. Some carbon (e.g. 70% of ash)
By leaving lead or tin in the ash, lead or tin exists in the ash in a metallic state, so it can be easily recovered from the ash using an appropriate method.

In the present invention, the gas conversion rate when tin is used as a catalyst is higher when carbon dioxide is used as a gasifying agent (11). In terms of effective use of carbon dioxide, it is preferable to install a carbon dioxide conversion plant near a factory that generates a large amount of carbon dioxide.

According to the present invention, it is possible to gasify coal with a high gasification rate and gas conversion rate at a temperature lower than the conventional gasification temperature. It is advantageous in terms of furnace material and thermal efficiency.

EXAMPLES The present invention will be specifically described below with reference to Examples.

Example/ As a raw material, a char having a carbon content of 9 mg wt % obtained by heat-treating a phenol resin at 000° C. in nitrogen gas and pulverizing it to a particle size of 7 q μm or less was used.

Tin oxide θ0 is used as a catalyst precursor for 1 g of this char.
Otsu g, lead oxide θ09fi, stannous sulfate 00 Otsu g, stannous oxalate θ0639 or stannous acetate θ093
g respectively, and with a mortar grinder, /
Grind and mix for hours. Each of the obtained mixtures was heated from room temperature to 1000°C at a heating rate of 10°C per minute using a thermobalance while flowing carbon dioxide at a flow rate of 23Qml per minute, and the conversion rate was calculated as a function of temperature in Figure 1. For comparison, a similar test was conducted on char shown in FIG. 2 without the addition of a catalyst.

As is clear from these results, when no catalyst is added, as shown by the curve / in Figure 1,
Even when heated to 100%, the conversion rate is only 6/6. On the other hand, curves C and 3 in Figure 1 are thermogravimetric curves when lead oxide and tin oxide are added, respectively, and it is clear that the addition of a catalyst increases the reaction rate, especially at temperatures above 50°C. It is recognized that this is true. Furthermore, as is clear from the results shown in FIG. 2, when tin is used as a catalyst, it is recognized that the catalytic activity is substantially unrelated to the form of tin addition.

Example stannous acetate/2. ! ;% aqueous solution 73ml and 3.5
Me was mixed with Charcot g used in Example/and impregnated, and a thermogravimetric curve was obtained in the same manner as in Example/.

The results are shown in FIG. 3 together with the results obtained using solid tin acetate in Example/.

As is clear from FIG. 3, no difference in catalytic activity was observed due to the difference in the addition method.

Example 3 A reaction tube with a diameter of 30 m and a length of sootrrm was placed vertically in an electric furnace, and a first particle with a particle size of 007 to 0.0 jtM was placed in the electric furnace.
10 g of coal (produced in Australia) having the composition shown in the table was added. This coal was mixed in advance by adding θQ ml of a 20% by weight solution of stannous acetate per kg of coal.

Table 1 Mixing ratio CO2/H20 from the bottom of this reaction tube (More)
Coal was gasified by maintaining the reaction tube temperature at 900° C. while supplying carbon dioxide and steam at a flow rate of 2 moles per hour. Three minutes after the reaction temperature reached 90g℃, the dry gas composition was H22/%, CoA3%.

CH, 0.7%, Co2/Otsuchi. It took 73 minutes for all of the coal to be gasified. Note that the amount of gasifier supplied was reduced in accordance with the amount of coal that decreased over time.

Similarly to the above, when the reaction temperature was set to gSθ°C and 9SO°C, the gasification completion time was 1IO minutes and 5 minutes, respectively. Incidentally, coal not impregnated with stannous acetate was gasified at 900° C. under the same conditions, but the gasification rate after 30 minutes was gθ.

Example q 07 kg of stannous acetate-impregnated coal similar to that used in Example 3 was charged into a test gasifier having an inner diameter of 3 cm and a height of gOcm. The particle size of the coal used was θ/~05.

This gasifier is supplied with 0.0% air. The coal was fed at a flow rate of 3/hr, and the combustion heat of the coal raised the temperature inside the furnace to 950'C. Then CO□10 mol/hr and
Gasification was carried out by supplying water until it dropped to . The average composition of the dry gas obtained during this period was 8220%, coigs.

CH, θ/%, C0, 22%. Check the furnace temperature 5
When the temperature reached 0℃, the supply of CO2 and H2O was
-1 Air is supplied again at a flow rate of Q,/m to carry out the oxidation reaction, and the temperature inside the furnace is raised to 9SO℃, -) (
- Gasification was performed by supplying C02, H, and O in the same manner as above.

[Brief explanation of drawings]

FIGS. 7, 2, and 3 are graphs showing the relationship between temperature and conversion rate to show the activity of the catalyst used in the method of the present invention. #ji person for patent Tokachi Tamai Figures 1 and 2

Claims (1)

[Claims] / A method for catalytic gasification of coal, which comprises reacting coal or carbide with carbon dioxide and/or water vapor at high temperature in the presence of lead or tin to gasify it.