JP7280718B2 - Gasification method of carbonaceous material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for gasifying carbonaceous materials, particularly low-rank coal with a relatively low degree of coalification such as lignite.

Among coals, lignite and lignite, which have a low degree of coalification, are difficult to transport due to their high water content, and may ignite if dried. Patent Literature 1 discloses a method of heating and dehydrating such low-grade coal and adsorbing heavy oil to make a solid fuel with low spontaneous combustion. By using such a modified solid fuel, it is possible to make it easier to use low-rank coal with a low degree of coalification, but coal emits carbon dioxide per unit calorific value when used for combustion. There is also the issue of volume.

A process is also known in which coal is gasified by a method such as partial combustion to obtain a gas containing hydrogen and carbon monoxide as main components, and this is subjected to a methanation reaction on a catalyst to obtain methane (Non-Patent Document 1, 2). In this method, coal is converted into methane and carbon dioxide, so by separating the carbon dioxide and sequestering it underground, natural gas has the lowest carbon dioxide emissions per unit calorific value among fossil fuels. It can be used as a fuel with low environmental impact similar to

However, the gasification of coal by the partial combustion method usually requires a high temperature of 1000° C. or more, and the equipment cost is high. Further, when gasified at a high temperature, the generated gas is mainly carbon monoxide and hydrogen, so about 20% of the heat is lost due to heat generation when methane is generated by the methanation reaction.

The gasification reaction of carbon (coal) with water vapor (reaction formula 1) is an endothermic reaction, whereas the methanation reaction (reaction formula 2) is an exothermic reaction. When carbon is gasified with water vapor to obtain a gas mainly composed of hydrogen, carbon monoxide and carbon dioxide, and this is converted to methane by a methanation reaction, the general reaction is almost thermally neutral. If gasification and methanation can be performed simultaneously, the heat generated by methanation can cover the endothermic heat of gasification, and efficient gasification can be achieved. However, while gasification generally requires a high temperature to obtain an effective reaction rate, methanation proceeds only at equilibrium low temperatures. It is extremely difficult to react.

C + H ₂ O (g) → CO + H ₂ ΔH = +131.3 kJ/mol (endothermic) (1)
CO+3H ₂ →CH ₄ +H ₂ O (g) ΔH=−206.2 kJ/mol (exothermic) (2)

It is known that by using a catalyst, coal can be gasified at a relatively low temperature of about 700° C. using water vapor as a gasifying agent (Non-Patent Document 3). It is known that alkali metals such as K, alkaline earth metals such as Ca, and transition metals such as Fe, Co and Ni are effective for gasification.

In Patent Document 2, in the catalytic gasification of fluidized petroleum coke using steam, the reaction temperature was changed in the range of 593 ° C. to 816 ° C., and the methane concentration of the produced gas was compared. %, decreases to 27.5% at 704°C and to 14.1% at 816°C. The use of K ₂ CO ₃ , Li ₂ CO ₃ , CaCO ₃ as catalysts is disclosed.

In Patent Document 3, in the steam gasification of coking bituminous coal containing about 30% of volatile matter, the bituminous coal is treated with a hydroxide of Na, K or Li and a hydroxide or carbonate of Ca, Mg or Ba. By mixing with an aqueous solution containing and hydrothermally treating at 150 to 375 ° C and then subjecting it to gasification, a gasification rate equivalent to the gasification of raw coal at 825 ° C at a gasification temperature of 675 ° C was obtained. is shown. However, there is no description of specific gasification performance (reaction time and gasification rate).

US Pat. No. 5,300,003 compares the effects of K, Na and Ca on steam gasification of bituminous coal at 704° C. (1300° F.). It shows that when _K2CO3 is used at 10 and 15% by weight of coal, the gasification rate per hour is 72,100% respectively, and when _Na2CO3 is used at 5% by weight of coal, it is 21 _{% .} %, 41% when using 2.9% by weight of Ca(OH) _{2 (} calculated as CaO), whereas 5% by weight of _Na2CO3 and 8% by weight of Ca(OH) ₂ based on coal % (calculated as CaO) when used together, the result is 47 to 89%, and the gasification promoting effect of Na or Ca alone is small, but the combined use of Na and Ca has a gasification effect close to that of K. It shows what you get. Since Na and Ca are generally cheaper than K, they are significant from the viewpoint of reducing catalyst costs.

Non-Patent Document 3 shows the results of steam gasification of various coals (carbon content of 66.5% to 83.6% on an anhydrous ashless basis) using a calcium hydroxide catalyst at 600 to 700 ° C. It is According to it, in steam gasification at 700 ° C, the effect of the Ca catalyst was large for coal with a carbon content of 75% or less, and a gasification rate of 95% or more was obtained in 1 hour. For those exceeding 75%, the gasification rate after 1 hour remains at about 60%.
It is also shown that lowering the gasification temperature to 650°C to 600°C significantly reduces the gasification rate.

Non-Patent Document 4 shows the results of steam gasification at 650 ° C. with iron, cobalt, and nickel as catalysts, but cobalt and nickel showed a gasification rate of over 80% in 1 hour. On the other hand, in iron, it remains at 70%, which is lower than these. However, cobalt and nickel are much more expensive than iron, making them difficult to use.

Non-Patent Document 5 describes alkali metals (Na, K), alkaline earth metals (Mg, Ca), Al and transition metals (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo) catalyzed by steam and hydrogen-steam gasification of carbonaceous materials. The effects of binary and ternary catalysts using two or three components have also been studied, and Na + Ca, Ca + Fe, Na + Fe and Na + Ca + Fe are effective for gasification with water vapor, carbon dioxide or a mixed gas thereof. , and that Fe+Ca and Fe+Ca+Na are effective for gasification with hydrogen. However, the supported amount of the investigated catalyst is as low as about 0.25% to 1% for each component, and the gasification temperature is as high as 800°C. It is unclear whether a practical gasification rate can be obtained at a low temperature range of about 650°C.

In addition, various methods such as impregnation, ion exchange, and simply mixing coal with metal salts containing catalyst components are known as methods for supporting alkali metals and alkaline earth metals, which serve as catalyst components, on coal. ing. For example, Non-Patent Document 3 discloses a method in which coal is added to a slurry containing Ca(OH) ₂ , homogenized by kneading, and then dried.

Patent Document 4 discloses a method in which coal is immersed in a saturated Ca(OH) ₂ solution to incorporate calcium ions into the coal by ion exchange, dried, and then mixed with Na ₂ CO ₃ . there is In this document, Na ₂ CO ₃ is simply mixed _with coal _carrying Ca by ion exchange. It is conceivable that it could not support

Patent Document 5 discloses a catalyst-supporting coal composition in which an alkali metal is used as a catalyst component, and more than 50% of the catalyst component is ion-exchange-supported by the acid functional groups of coal.

However, it is unclear what kind of supporting method is suitable for obtaining a practical gasification rate at a low temperature range of 700° C. or less, especially about 550 to 650° C.

JP-A-7-233383 JP-A-47-23658 JP-A-51-122103 JP-A-54-122304 WO2009/018053

Perry M, Eliason D.; "C02 recovery and sequence at Dakota Gasification Company Inc.", Technical report, Gasification Technology Conference, 2004. Kopyscinski et al., Fuel, Vol. 89, 2010, p. 1763-1783 Yasuo Ohtsuka and Kenji Asami, Energy and Fuels, Vol. 9, 1995, p. 1038-1042 Yasuo Ohtsuka et al., Energy and Fuels, Vol. 1, 1987, p. 32-36 Tetsuya Haga et al., Applied Catalysis, Vol. 67, 1991, p. 189-202

The object of the present invention is to use an inexpensive catalyst, and at a low temperature range of 700 ° C. or less where methane production is advantageous in terms of chemical equilibrium, using water vapor as a gasification agent, a carbonaceous material such as low-rank coal at a high reaction rate. To provide a highly efficient and economical gasification method for low-rank coal by gasifying at.

The present invention provides a method for gasifying a carbonaceous material as described below.

The second characteristic configuration of the method for gasifying a carbonaceous material according to the present invention is 60 to 75 on an anhydrous and ashless basis.
A method for gasifying a carbonaceous material containing mass % carbon, wherein the carbonaceous material is an aqueous solution containing a water-soluble salt of calcium, an aqueous solution containing a water-soluble salt of sodium, and an aqueous solution containing a water-soluble salt of iron. Then, simultaneously or sequentially, the carbonaceous material is added with calcium in a mass ratio of 1.5% to 6% with respect to the carbonaceous material (dry mass) and 1 in a mass ratio with respect to the carbonaceous material (dry mass). a supporting step of supporting 5% to 6% sodium and 1.5% to 6% iron in mass ratio to said carbonaceous material (dry mass); a gasification step of contacting the material with a gasifying agent containing water vapor under a temperature condition of 550 to 700° C., wherein the gases obtained by the gasification step are hydrogen, carbon monoxide, carbon dioxide, and It is in that it contains methane.

In the carbonaceous material according to the present invention, if the carbon content of the carbonaceous material is within the above range, it is advantageous from the viewpoint of the gasification rate and post-treatment of the produced gas. Further, when the gasification temperature is within the above range, it is advantageous from the viewpoint of the gasification rate and the composition of the produced gas. Furthermore, the method for gasifying a carbonaceous material according to the present invention uses relatively inexpensive calcium and sodium, which is advantageous in that it can be performed at a lower cost than conventional gasification methods.

In the carbonaceous material according to the present invention, when a catalyst containing iron in addition to calcium and sodium is used, gasification is promoted especially at low temperatures of 600 ° C. or less, and the activity of iron for the CO shift reaction is high. Therefore, it is advantageous in that the CO concentration in the produced gas can be reduced.

A further characteristic configuration of the carbonaceous material gasification method according to the second characteristic configuration of the present invention is that the supporting step includes an aqueous solution containing a water-soluble salt of calcium, a water-soluble salt of sodium, and a water-soluble salt of iron. Second, it has an impregnation step of impregnating the carbonaceous material.

In the gasification method according to the present invention, the use of a loading step having an impregnation step is advantageous in that the loading amount can be easily controlled.

The method for gasifying carbonaceous materials of the present invention rapidly gasifies inexpensive carbonaceous materials such as low-grade coal in a low temperature range of 700° C. or less, so that alternative natural gas can be obtained economically with high efficiency. can be done.

Hereinafter, embodiments of the present invention will be described in detail.

The method for gasifying a carbonaceous material of the present invention is a method for gasifying a carbonaceous material containing 60 to 75% by mass of carbon on an anhydrous and ashless basis, wherein the carbonaceous material contains a water-soluble salt of calcium. A supporting step of supporting calcium and sodium on the carbonaceous material by simultaneously or sequentially contacting an aqueous solution and an aqueous solution containing a water-soluble salt of sodium; and a gasification step of contacting with a gasification agent containing water vapor under a temperature condition of ° C., wherein the gas obtained by the gasification step contains hydrogen, carbon monoxide, carbon dioxide, and methane. Characterized by

The method for gasifying a carbonaceous material of the present invention is, as one aspect, a method for gasifying a carbonaceous material containing 60 to 75% by mass of carbon on an anhydrous and ashless basis, wherein the carbonaceous material is added with calcium in a water solution. an impregnating step (an example of a supporting step) of impregnating the carbonaceous material with an aqueous solution containing an aqueous salt and a water-soluble salt of sodium; and a gasification step, wherein the gas obtained by the gasification step contains hydrogen, carbon monoxide, carbon dioxide, and methane.

The method for gasifying a carbonaceous material of the present invention is, as one aspect, a method for gasifying a carbonaceous material containing 60 to 75% by mass of carbon on an anhydrous and ashless basis, wherein the carbonaceous material is dissolved in an aqueous solution of calcium. An adsorption step (example of a supporting step) of immersing the carbonaceous material in an aqueous solution containing an aqueous salt and an aqueous solution containing a water-soluble salt of sodium, separating the liquid by filtration, and then drying, and the carbonaceous material supporting calcium and sodium, a gasifying step of contacting with a gasifying agent containing water vapor under a temperature condition of ~700°C, wherein the gas obtained by the gasifying step comprises hydrogen, carbon monoxide, carbon dioxide, and methane. It is characterized by In the adsorption step, the carbon material may be immersed in a mixed aqueous solution containing a water-soluble salt of calcium and a water-soluble salt of sodium and then filtered and dried. The aqueous solution containing the organic salt may be soaked, filtered and dried separately.

In one aspect of the carbonaceous material gasification method of the present invention, the aqueous solution preferably further contains a water-soluble iron salt. Since iron is highly active in the CO shift reaction, it is effective in reducing the CO concentration in the produced gas and promotes gasification at low temperatures.

As the carbonaceous material, any carbonaceous material containing 60 to 75% by mass of carbon on an anhydrous and ashless basis and solid at room temperature may be used, but brown coal or lignite is usually used. In addition, biomass such as wood may be heat-treated (semi-carbonized) at about 250 to 400° C. in an inert gas atmosphere to adjust the carbon content to the range described above.

A carbonaceous material with a higher carbon content will have a slower gasification rate, making it difficult to gasify at a practical rate. Conversely, carbonaceous materials with a lower carbon content, such as wood that has not been semi-carbonized, gasify quickly, but produce a large amount of tar during gasification, making post-treatment of the product gas difficult. become necessary.

The gasification temperature is 550-700°C. At temperatures below 550° C., it becomes difficult to gasify at a practical rate even with a highly active catalyst. On the other hand, if the temperature is higher than 700°C, methane will not be generated in equilibrium even when gasification is performed under high pressure, and the heat generated by methanation cannot compensate for the endothermic heat of the gasification reaction, so external heating is required. gasification cannot proceed. Moreover, if the temperature is higher than 700° C., the gasification reaction itself can proceed not only with the catalyst disclosed in the present invention but also with a conventionally known catalyst such as potassium. The lower limit of the gasification temperature is preferably 600°C, more preferably 650°C.

In the carbonaceous material gasification method of the present invention, a calcium salt and a sodium salt are used in combination as catalysts for promoting gasification. These are impregnated and supported on carbonaceous materials and act as gasification catalysts. Specifically, a mixed aqueous solution containing calcium salts and sodium salts is prepared using water-soluble compounds such as nitrates and carbonates. obtain. A gas containing hydrogen, carbon monoxide, carbon dioxide and methane is obtained by contacting this with a gasifying agent containing water vapor at a predetermined temperature.

The amount of catalyst component supported on the carbonaceous material can be controlled by a known method, for example, by the method exemplified below. When the equilibrium adsorption method exemplified first is used, an aqueous solution containing the component to be supported is prepared, the carbonaceous material is immersed in this, the liquid is separated by filtration, and then dried (ion exchange method ) yields a catalyst-supported carbonaceous material. In this case, the supported amount depends on the concentration of the aqueous solution in which the carbonaceous material is immersed and the duration of immersion in the aqueous solution. Therefore, by controlling these conditions in the impregnation step, a carbonaceous material carrying an arbitrary amount of catalyst can be obtained. In the present invention, calcium and sodium may be supported simultaneously or sequentially. When simultaneously supported, a mixed aqueous solution containing a calcium salt and a sodium salt is used as the above aqueous solution. In the case of sequential loading, an aqueous solution containing either a calcium salt or a sodium salt is used as the above aqueous solution to load one of the metals, and then an aqueous solution containing the other salt is used to load the other metal. Let Similarly, when three or more components are supported, all components may be supported simultaneously, or some or all of the components may be supported sequentially.

When the evaporation to dryness method exemplified second is used, a mixed aqueous solution containing calcium salts and sodium salts is prepared, the carbonaceous material is immersed in this, and then the water is removed by evaporation to support the catalyst. A carbonaceous material is obtained. In this case, the supported amount is determined by the amount of metals (calcium and sodium) contained in the aqueous solution.

In the evaporation to dryness method, all of the metal used is supported, so the amount of support can be easily controlled. On the other hand, the degree of dispersion of supported metals is generally higher in the equilibrium adsorption method, so even if the amount of catalyst components supported is the same as when the catalyst component is supported by the evaporation to dryness method, a higher catalytic effect is likely to be obtained. .

Here, if the amount of the catalyst component supported on the carbonaceous material is too small, there is no effect of promoting gasification. The mass ratio of each metal component is preferably 1.5% to 10%, more preferably 1.5% to 6%, even more preferably 2% to 6%, and 2 to 5%. is particularly preferred. In addition to the above calcium and sodium, when iron is further supported, the mass ratio of each metal component to the carbonaceous material (dry mass) is preferably 1.5% to 6%, preferably 2% to 6%. %, and particularly preferably 2 to 5%.

When the catalyst component is supported on the carbonaceous material by the equilibrium adsorption method (ion exchange method), a higher catalytic effect is likely to be obtained than when the catalyst component is supported by the evaporation to dryness method, as described above. small value. Specifically, when the equilibrium adsorption method (ion exchange method) is used, the mass ratio of each metal component to the carbonaceous material (dry mass) for both calcium and sodium is preferably 0.1 to 10%. .2 to 10% is more preferable.

The pressure of the gasification reaction is not particularly limited, but the higher the pressure, the more advantageous the methane production in equilibrium.
Therefore, when the purpose is to generate methane, the pressure is preferably 0.5 MPa or higher, more preferably 1 MPa or higher.

If the amount of water vapor as a gasifying agent is too small, the gasification reaction will not proceed at a sufficient rate, while if it is too large, the steam reforming reaction of methane will be favored in equilibrium. There is a problem that the energy efficiency of gasification decreases because the methane concentration in the gas decreases and the yield of methane decreases, and additional energy is required to generate steam. Therefore, in general, the molar ratio (S/C) of steam (water) S to the substance amount C of carbon atoms in coal is preferably 1 to 10, more preferably 1.5 to 5.0. do.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[Preparation of catalyst-supporting carbonaceous material and evaluation of gasification rate]
Samples A to U were prepared as shown below, and the gasification rate was evaluated for the samples A to U.
Note that samples A, I, M, N, O, R, S, and T prepared by supporting calcium and sodium, and samples B, J and prepared by supporting calcium, sodium, and iron, and , P are examples of the present invention. Samples G, H, and L prepared by supporting a catalyst containing potassium are reference examples of the present invention, and the other samples C, D, E, F, K, Q, and U are It is a comparative example of the present invention.

<<Sample A>>
Australian Loy Yang brown coal (brown coal X) was used as the carbonaceous material. The industrial analysis results of this lignite X were 59.3% moisture, 22.1% volatile matter, 18.2% fixed carbon, and 0.4% ash (all on a mass basis, the same applies below). In addition, the elemental composition based on the anhydrous ashless standard was C: 70.9%, H: 4.56%, O: 23.7%, N: 0.63%, and S: 0.26%.

The brown coal was dried to a moisture content of 17%, pulverized and classified to 53-150 μm.
The dry brown coal was then loaded with the catalyst using the evaporation to dryness method. Specifically, a mixed aqueous solution of calcium nitrate and sodium nitrate is prepared, mixed with the above-mentioned classified brown coal X, mixed well, dried under reduced pressure at room temperature, and further dried at 107° C. for 2 hours under nitrogen flow. Then, sample A was obtained. At this time, the concentrations of calcium nitrate and sodium nitrate were adjusted so that the amounts of Ca and Na contained in the mixed aqueous solution relative to the mass of dry brown coal were 5.1% Ca and 5.3% Na. .

After acidolysis of sample A, the supported amount was quantified by ICP analysis. The amounts of Ca and Na carried by sample A (the amount of metals carried per unit mass of dry brown coal) were 5.1% Ca and 5.3% Na.

Gasification evaluation of sample A was performed using a differential thermal balance (TG-DTA/HUM-1 manufactured by Rigaku Corporation). About 20 mg of sample A is loaded, and a gas consisting of 20% steam and the balance nitrogen is circulated at a flow rate of 300 mL / min, and the temperature is increased by 10 ° C. / min to a predetermined temperature (550 ° C., 600 ° C., 650 ° C., 700 ° C.). After the temperature was raised at a temperature rate, the temperature was maintained at a predetermined temperature, and the mass reduction rate (with respect to the sample amount excluding moisture, ash, and catalyst components) after 1 hour was taken as the gasification rate.

As shown in Table 1, the gasification rates at 550°C, 600°C, 650°C and 700°C were 58.6%, 79.8%, 95.3% and 94.2%, respectively.

<<Sample B>>
Sample B was obtained in the same manner except that the same brown coal X as in the preparation of sample A was used, and a mixed aqueous solution of calcium nitrate, sodium nitrate and iron (III) nitrate was used instead of the mixed aqueous solution of calcium nitrate and sodium nitrate. rice field. The amounts of Ca, Na, and Fe carried in sample B (the amount of metals carried per unit mass of dry brown coal) were 5.7% Ca, 6.0% Na, and 5.9% Fe.

Regarding sample B, gasification evaluation was performed in the same manner as sample A.

As shown in Table 1, the gasification rates at 550°C, 600°C, 650°C and 700°C were 65.5%, 84.7%, 96.5% and 95.4%, respectively.

<<Sample C>>
The same lignite X as in the preparation of sample A was used without supporting a catalyst (referred to as sample C).

Regarding sample C, gasification evaluation was performed in the same manner as sample A.

As shown in Table 1, the gasification rates at 600°C, 650°C and 700°C were 47.5%, 54.2% and 57.4%, respectively. It can be seen that the gasification rate is low when no catalyst is supported. Since the volatile content of lignite X is about 55% on a dry basis, the obtained results show that the fixed carbon content can hardly be gasified even at 700° C. in the absence of a catalyst.

<<Sample D>>
Sample D was obtained in the same manner except that the same lignite X as in the preparation of Sample A was used, and an aqueous solution of sodium carbonate was used instead of the mixed aqueous solution of calcium nitrate and sodium nitrate. The amount of Na supported on sample D was 4.9%.

Regarding sample D, gasification evaluation was performed in the same manner as sample A. As shown in Table 1, the gasification rates at 600°C, 650°C and 700°C were 60.3%, 88.1% and 94.0%, respectively.

<<Sample E>>
Sample E was obtained in the same manner except that the same lignite X as in the preparation of sample A was used, and an aqueous solution of calcium nitrate was used instead of the mixed aqueous solution of calcium nitrate and sodium nitrate. The amount of Ca supported on sample E was 5.1%.

Regarding sample E, gasification evaluation was performed in the same manner as sample A. As shown in Table 1, the gasification rates at 600°C, 650°C and 700°C were 64.2%, 86.9% and 97.4%, respectively.

<<Sample F>>
Sample F was obtained in the same manner except that the same lignite X as in the preparation of sample A was used, and an aqueous solution of iron (III) nitrate was used instead of the mixed aqueous solution of calcium nitrate and sodium nitrate. The amount of Fe supported on sample F was 5.5%.

Regarding sample F, gasification evaluation was performed in the same manner as sample A. As shown in Table 1, the gasification rates at 600°C, 650°C and 700°C were 53.4%, 64.8% and 80.8%, respectively.

<<Sample G>>
Sample G was obtained in the same manner except that the same lignite X as in the preparation of sample A was used, and an aqueous solution of potassium carbonate was used instead of the mixed aqueous solution of calcium nitrate and sodium nitrate. The amount of K carried in sample G was 4.8%.

Regarding sample G, gasification evaluation was performed in the same manner as sample A. As shown in Table 1, the gasification rates at 600°C, 650°C and 700°C were 70.0%, 95.2% and 97.7%, respectively.

<<Sample H>>
Sample H was obtained in the same manner except that the same lignite X as in the preparation of sample A was used, and an aqueous solution of potassium nitrate was used instead of the mixed aqueous solution of calcium nitrate and sodium nitrate. The amount of K carried in sample H was 5.1%.

For sample H, gasification evaluation was performed in the same manner as for sample A. As shown in Table 1, the gasification rates at 600°C, 650°C and 700°C were 73.0%, 97.1% and 97.1%, respectively.

Comparing the above results, the method of the present invention, in which both calcium and sodium are supported as catalysts, gives a gasification rate similar to that of potassium at 650°C, and faster than that of potassium at lower temperatures. It can be seen that the effect of promoting gasification is high. It is also found that when calcium, sodium or iron is used alone, the effect of promoting gasification is small.

<<Sample I>>
Australian Loy Yang brown coal (brown coal Y) was used as the carbonaceous material. Industrial analysis results of this lignite Y were 61.3% moisture, 20.2% volatile matter, 17.8% fixed carbon, and 0.7% ash (both on a mass basis, the same below). In addition, the elemental composition based on the anhydrous ashless standard was C: 66.8%, H: 5.30%, O: 26.9%, N: 0.57%, and S: 0.35%.

Sample I was prepared in the same manner as sample A, except that lignite Y was used instead of lignite X. The amount of Ca and Na supported in sample I (the amount supported in terms of metal per unit mass of dry brown coal) was 5.6% Ca and 5.6% Na.

Sample I was evaluated for gasification in the same manner as Sample A. As shown in Table 1, the gasification rates at 550°C, 600°C and 700°C were 59.4%, 76.7% and 98.0%, respectively.

《Sample J》
Sample J was obtained in the same manner except that the same lignite Y as in the preparation of sample I was used, and a mixed aqueous solution of calcium nitrate, sodium nitrate and iron (III) nitrate was used instead of the mixed aqueous solution of calcium nitrate and sodium nitrate. rice field. The amounts of Ca, Na and Fe supported on sample J were 5.5% Ca, 5.5% Na and 5.3% Fe.

Regarding sample J, gasification evaluation was performed in the same manner as sample A. As shown in Table 1, the gasification rates at 550°C, 600°C and 700°C were 64.5%, 82.9% and 96.8%, respectively.

《Sample K》
Sample K was obtained in the same manner as in the preparation of Sample I, except that the same lignite Y as in the preparation of Sample I was used, and an aqueous solution of sodium nitrate was used instead of the mixed aqueous solution of calcium nitrate and sodium nitrate. The amount of Na carried in sample K was 4.8%.

Regarding sample K, gasification evaluation was performed in the same manner as sample A. As shown in Table 1, the gasification rates at 600°C, 650°C and 700°C were 66.3%, 90.3% and 95.4%, respectively.

<<Sample L>>
Sample L was obtained in the same manner except that the same lignite Y as in the preparation of sample I was used, and a mixed aqueous solution of calcium nitrate and potassium nitrate was used instead of the mixed aqueous solution of calcium nitrate and sodium nitrate. The Ca and K loadings of sample L were 5.1% and 4.8%, respectively.

Regarding sample L, gasification evaluation was performed in the same manner as sample A. As shown in Table 1, the gasification rates at 600°C and 700°C were 78.8% and 97.0%, respectively. From the comparison with sample I, the gasification performance of the two-component catalyst of Ca and K is almost the same as that of Ca and Na, and the method of the present invention using Na, which is cheaper than K, is advantageous.

<<Samples M to P>>
Samples M, N, O, and P were prepared by using the same lignite Y as in the preparation of sample I, but with different loadings of Ca, Na, and Fe, and the gasification performance was evaluated.

As shown in Table 1, the gasification rate at 600° C. is 69.5 to 74.9%, which is higher than the sample K supporting 4.8% of Na alone, and the catalyst of the present invention composited with calcium and sodium. It is clear that the gasification performance is high.

<<Sample Q>>
The same lignite Y as in the preparation of Sample I was used without supporting a catalyst (Sample Q).

For sample Q, gasification evaluation was performed in the same manner as for sample A. As shown in Table 1, the gasification rate at 550°C was 45.7%. Comparing the results of sample I and sample J, it can be seen that gasification of fixed carbon proceeds even at a low temperature of 550° C. when the catalyst is supported.

<<Sample R>>
The same lignite Y as in the preparation of sample I was dried under reduced pressure at room temperature and classified to 53 to 150 μm. 30 g of this coal was boiled in 300 mL of an aqueous sodium nitrate solution (0.222 mol/L) for 3 hours to carry Na ion-exchanged on the coal, and then filtered to recover Na ion-exchanged coal. Next, a solution was prepared by suspending 3 g of Ca(OH) ₂ in 300 mL of ion-exchanged water, and the Na ion-exchanged carbon was added thereto. Ca ion exchange was performed over 3 days while stirring several times a day for about 1 hour each time. Ca—Na ion-exchanged carbon was recovered by filtration. It was dried at room temperature, further dried under reduced pressure, dried under reduced pressure at 107° C. for 2 hours, and classified to 53 to 150 μm to obtain Sample R. Sample R had an Na-supported amount of 0.24% and a Ca-supported amount of 5.1%.

For sample R, gasification evaluation was performed in the same manner as for sample A. As shown in Table 1, the gasification rate at 600°C was 79.2%. Comparing the results of sample I and sample N, it can be seen that gasification proceeds efficiently even with a very small amount of Na supported when the ion exchange method is used.

<<Sample S>>
The same lignite Y as in the preparation of sample I was dried under reduced pressure at room temperature and classified to 53 to 150 μm. A 300 mL sodium nitrate aqueous solution (0.222 mol/L) in which 3 g of Ca(OH) ₂ was suspended was prepared, and 30 g of the above coal was added thereto. Ca and Na ion exchange was performed over 3 days while stirring several times a day for about 1 hour each time. Ca—Na ion-exchanged carbon was recovered by filtration. It was dried at room temperature, further dried under reduced pressure, dried under reduced pressure at 107° C. for 2 hours, and classified to 53 to 150 μm to obtain Sample S. Sample S had an Na-supported amount of 1.0% and a Ca-supported amount of 4.8%.

Regarding sample S, gasification evaluation was performed in the same manner as sample A. As shown in Table 1, the gasification rate at 600°C was 81.9%. Comparing the results of sample I and sample N, it can be seen that gasification proceeds efficiently even with a small amount of Na supported when the ion exchange method is used. Although the required amount of Na is increased compared to the sample R, there is an advantage that the process is simple because Na and Ca are simultaneously ion-exchanged.

<<Sample T>>
The same lignite Y as in the preparation of sample I was dried under reduced pressure at room temperature and classified to 53 to 150 μm. A solution was prepared by suspending 2.4 g of Ca(OH) ₂ in 240 mL of ion-exchanged water, and 24 g of the above coal was added thereto. Ca ion exchange was performed over 3 days while stirring several times a day for about 1 hour each time. Ca ion-exchanged coal was recovered by filtration. Ca ion-exchanged charcoal dried at room temperature was thoroughly mixed with an aqueous sodium nitrate solution, dried under reduced pressure at room temperature, and further dried under reduced pressure at 107° C. for 2 hours to obtain sample T. At this time, the concentration of sodium nitrate was adjusted so that the mass ratio of Na contained in the sodium nitrate aqueous solution to the dry brown coal was 5%. Sample T had an Na-supported amount of 4.7% and a Ca-supported amount of 4.6%.

Regarding sample T, gasification evaluation was performed in the same manner as sample A. As shown in Table 1, the gasification rate at 550°C was 67.8% and the gasification rate at 600°C was 87.5%. Comparing the results of sample I and sample N, it can be seen that extremely high gasification performance is exhibited even at low temperatures when Ca is supported first by the ion exchange method and then Na is supported by the impregnation method.

<<Sample U>>
The same lignite X as in the preparation of sample A was air-dried at room temperature, dried under reduced pressure, pulverized, and classified to 53 to 150 μm. 0.2 g of Ca(OH) ₂ was added to 20 mL of distilled water and stirred. 2 g of the dried lignite was added thereto and stirred at room temperature for 18 hours to perform ion exchange.

The solid content collected by filtration was dried naturally at room temperature, then dried under reduced pressure, and further dried at 107° C. for 2 hours under nitrogen flow to obtain sample U. The amount of Ca supported on sample U was 5.1%.
For sample U, gasification evaluation was performed in the same manner as for sample A. As shown in Table 1, the gasification rate at 600°C was 63.9%. Comparing the results of sample U and sample E, there is no significant difference in gasification rate between the two. That is, it can be seen that the gasification rate is hardly improved simply by changing the method of supporting Ca to ion exchange. Further, when comparing the results of sample T and sample U, it can be seen that both Ca and Na are required to be supported in order to obtain high gasification performance.

[Gasification test]
Gasification Tests 1-7 were performed as shown below. Gasification Tests 1, 2, and 4 using Sample I (described above) prepared with calcium and sodium supported, and Sample J (described above) prepared with calcium, sodium, and iron supported. Gasification Test 5 and Gasification Test 8 using Sample R (described above) prepared with loaded calcium and sodium are examples of the present invention. In addition, gasification tests 3 and 6 using sample V (described later) prepared by supporting potassium are reference examples of the present invention, and sample Q (described above) prepared without supporting a metal catalyst was used. Gasification Test 7 is a comparative example of the present invention.

<<Gasification Test 1 Sample I>>
Using Sample I, a fluidized bed gasification test was performed. The fluidized bed reactor is made of stainless steel, and the fluidized portion has an inner diameter of 22 mm, a height of 50 mm, and a volume of 20 mL. is heated to a predetermined temperature. A mixed gas of steam and nitrogen is introduced as a gasification agent through a stainless steel filter at the bottom of the reactor. On the other hand, the upper part of the reactor is equipped with a screw feeder, and coal samples are continuously introduced. In order to prevent dew condensation on the screw feeder section, a small amount of nitrogen gas is also introduced into the screw feeder section. The gas produced by gasification is introduced into a flowmeter and a gas chromatograph through traps of ice water (second stage) and dry ice (first stage) and analyzed.

The internal temperature of the reaction tube was controlled at 700° C., and the sample I was fed into the fluidized bed reactor continuously for 150 minutes at a feeding rate of 51.9 mg/min (1.91 mmol/min as carbon feed rate).
As a gassing agent, water was introduced at a flow rate of 74.1 mg/min mixed with 40 mL/min of nitrogen. Nitrogen was also introduced at 48 mL/min from the screw feeder. Water was continuously added for 60 minutes after the end of adding sample I. After the addition of water, nitrogen continued to flow until the replacement of the gas in the reaction tube was completed, and all the gasified gas was recovered. As shown in Table 2, the product gases were 314 mmol hydrogen, 53 mmol carbon monoxide (CO), 159 mmol carbon dioxide ( _CO2 ), 6.0 mmol methane, 2.7 mmol C2 (ethane and ethylene), 2.7 mmol C3 (propane and propylene ) contained 0.6 mmol. The carbon-based gasification rate was 78.2%. The S/C ((moisture content in the sample and water vapor supplied as a gasification agent)/(carbon in the sample) molar ratio) in this test was 3.08.

<<Gasification Test 2 Sample I>>
Using Sample I, a gasification test in a fluidized bed was conducted in the same manner as gasification test 1 except for the following.
Input rate of sample I: 54.7 mg/min (2.02 mmol/min as carbon supply rate), flow rate of water as gasifying agent: 108.2 mg/min.

As shown in Table 2, the product gas contained 355 mmol hydrogen, 47 mmol carbon monoxide, 184 mmol carbon dioxide, 6.6 mmol methane, 2.8 mmol C2 (ethane and ethylene), 0.7 mmol C3 (propane and propylene). board. The carbon-based gasification rate was 80.5%. In this test, S/C (molar ratio of (moisture in the sample and water vapor supplied as a gasifying agent)/(carbon in the sample)) was 4.24.

<<Gasification Test 3 Sample V>>
Sample V was obtained in the same manner except that the same lignite Y as in Sample I was used, and an aqueous solution of potassium nitrate was used in place of the mixed aqueous solution of calcium nitrate and sodium nitrate. The amount of K carried in sample V was 4.1%.

Using Sample V, a gasification test in a fluidized bed was conducted in the same manner as gasification test 1 except for the following.
Input rate of sample V: 44.5 mg/min (2.15 mmol/min as carbon supply rate), flow rate of water as gasifying agent: 69.2 mg/min.

As shown in Table 2, the product gas contained 356 mmol hydrogen, 67 mmol carbon monoxide, 162 mmol carbon dioxide, 8.2 mmol methane, 3.3 mmol C2 (ethane and ethylene), 0.8 mmol C3 (propane and propylene). board. The carbon-based gasification rate was 76.5%. The S/C ((moisture content in the sample and water vapor supplied as a gasification agent)/(carbon in the sample) molar ratio) in this test was 2.55.

<<Gasification Test 4 Sample I>>
Using Sample I, a gasification test in a fluidized bed was conducted in the same manner as gasification test 1 except for the following.
Temperature inside the reaction tube: 650° C., input rate of sample I: 45.5 mg/min (1.68 mmol/min as carbon supply rate), flow rate of water as gasifying agent: 65.0 mg/min.

As shown in Table 2, the product gas contained 231 mmol hydrogen, 27 mmol carbon monoxide, 126 mmol carbon dioxide, 5.3 mmol methane, 1.9 mmol C2 (ethane and ethylene), 0.5 mmol C3 (propane and propylene). board. The carbon-based gasification rate was 65.1%. The S/C ((moisture content in the sample and water vapor supplied as a gasification agent)/(carbon in the sample) molar ratio) in this test was 3.08.

<<Gasification Test 5 Sample J>>
Using Sample J, a gasification test in a fluidized bed was conducted in the same manner as gasification test 1 except for the following.
Inner temperature of reaction tube: 650° C., input rate of sample J: 57.0 mg/min (carbon feed rate: 2.03 mmol/min), flow rate of water as gasifying agent: 77.0 mg/min.

As shown in Table 2, the product gas contained 276 mmol hydrogen, 31 mmol carbon monoxide, 161 mmol carbon dioxide, 5.3 mmol methane, 1.8 mmol C2 (ethane and ethylene), 0.5 mmol C3 (propane and propylene). board. The carbon-based gasification rate was 66.0%. In this test, S/C (molar ratio of (moisture in the sample and water vapor supplied as a gasifying agent)/(carbon in the sample)) was 3.00.

Comparing gasification test 4 and gasification test 5, the total amount of hydrogen, carbon monoxide, carbon dioxide, methane, C2 (ethane and ethylene), and C3 (propane and propylene) contained in the generated gas The ratio of carbon monoxide to gas was 6.9% in gasification test 4 and 6.5% in gasification test 5. That is, gasification test 5 using a catalyst containing Fe was able to reduce the carbon monoxide concentration in the generated gas more than gasification test 4 using a catalyst containing no Fe.

<<Gasification Test 6 Sample V>>
Using Sample V, a gasification test in a fluidized bed was conducted in the same manner as gasification test 1 except for the following.
Temperature inside the reaction tube: 650° C., input rate of sample V: 51.8 mg/min (2.50 mmol/min as carbon supply rate), flow rate of water as gasifying agent: 95.0 mg/min.

As shown in Table 2, the product gas contained 327 mmol hydrogen, 34 mmol carbon monoxide, 166 mmol carbon dioxide, 7.8 mmol methane, 2.7 mmol C2 (ethane and ethylene), 0.8 mmol C3 (propane and propylene). board. The carbon-based gasification rate was 57.3%. In this test, S/C (molar ratio of (moisture in the sample and water vapor supplied as a gasifying agent)/(carbon in the sample)) was 3.01.

Comparing gasification tests 4 and 5 with gasification test 6, the gasification methods of gasification tests 4 and 5 performed better than that of gasification test 6 at the carbon-based gasification rate at 650°C. , showing a remarkably high gasification rate.

<<Gasification Test 7 Sample Q>>
A gasification test in a fluidized bed was carried out in the same manner as in gasification test 1, except for the following, using sample Q (that is, lignite Y with no catalyst component supported). Inner temperature of reaction tube: 650° C., input rate of sample Q: 36.9 mg/min (1.81 mmol/min as carbon feed rate), flow rate of water as gasifying agent: 87.1 mg/min.

As shown in Table 2, the product gas contained 40 mmol hydrogen, 12 mmol carbon monoxide, 30 mmol carbon dioxide, 6.4 mmol methane, 1.9 mmol C2 (ethane and ethylene), 0.6 mmol C3 (propane and propylene). board. The carbon-based gasification rate was 19.4%. In this test, S/C (molar ratio of (moisture in the sample and water vapor supplied as a gasifying agent)/(carbon in the sample)) was 3.87. It is clear that the gasification rate is extremely low when no catalyst is supported.

<<Gasification Test 8 Sample R>>
Using Sample R, a gasification test in a fluidized bed was conducted in the same manner as gasification test 1 except for the following. Temperature inside the reaction tube: 650° C., input rate of sample R: 39.6 mg/min (1.64 mmol/min as carbon supply rate), flow rate of water as gasifying agent: 64.8 mg/min.

As shown in Table 2, the product gas contained 234 mmol hydrogen, 27 mmol carbon monoxide, 116 mmol carbon dioxide, 9.5 mmol methane, 2.3 mmol C2 (ethane and ethylene), 1.2 mmol C3 (propane and propylene). board. The carbon-based gasification rate was 65.6%. In this test, S/C (molar ratio of (moisture in the sample and water vapor supplied as a gasifying agent)/(carbon in the sample)) was 3.20. Compared with sample I, sample R had a smaller amount of sodium supported, but the gasification rate was equivalent to that of sample I.

Claims (2)

A method for gasifying a carbonaceous material containing 60 to 75% by mass of carbon on an anhydrous and ashless basis, comprising:
The carbonaceous material is brought into contact with an aqueous solution containing a water-soluble salt of calcium, an aqueous solution containing a water-soluble salt of sodium, and an aqueous solution containing a water-soluble salt of iron, simultaneously or sequentially. calcium in a mass ratio of 1.5% to 6% relative to the carbonaceous material (dry mass), sodium in a mass ratio of 1.5% to 6% relative to the carbonaceous material (dry mass), and the carbonaceous material (dry mass ) to support 1.5% to 6% iron by mass ratio,
a gasification step of contacting the carbonaceous material supporting calcium, sodium, and iron with a gasifying agent containing water vapor under a temperature condition of 550 to 700° C.;
A method for gasifying a carbonaceous material, wherein the gas obtained by the gasification step contains hydrogen, carbon monoxide, carbon dioxide, and methane. 2. The carbonaceous material gas according to claim 1 , wherein the supporting step comprises an impregnation step of impregnating the carbonaceous material with an aqueous solution containing a water-soluble salt of calcium, a water-soluble salt of sodium, and a water-soluble salt of iron. conversion method.