JPS6349719B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the gasification of carbonaceous feedstocks such as oil, petroleum residues, coal and the like, and more particularly to the
It relates to a catalytic gasification operation carried out in the presence of an alkali metal-containing catalyst.

It has long been recognized that certain alkali metal compounds can be used to catalyze the gasification of carbonaceous materials such as coal and other carbonaceous solids. Studies have shown that potassium carbonate, sodium carbonate, cerium carbonate and lithium carbonate can be extracted from steam, hydrogen, carbon dioxide, oxygen, etc. from bituminous coal, subbituminous coal, lignite, petroleum coke, organic waste and similar carbonaceous materials. It has been shown to substantially accelerate the rate of reaction with solids to produce methane, carbon monoxide, hydrogen, carbon dioxide and other gaseous products. However, other alkali metal salts, such as alkali metal chlorides, have lower catalytic activity compared to the corresponding carbonates. Due to the relatively high cost of cerium carbonate and the low effectiveness of lithium and sodium carbonates, most of the experimental work in this field conducted in the past has been directed to the use of potassium carbonate.

In addition to the use of individual alkali metal salts as catalysts for the gasification of carbonaceous materials, it has been proposed to use mixtures of alkali metal salts. When mixtures of such alkali metal salts are used to promote the gasification of carbonaceous feedstocks, the mixture promotes less of the gasification reaction than when equal amounts of the more active alkali metal compound are used alone. However, it is also expected that the gasification reaction will be promoted more than when an equal amount of the less active alkali metal salt is used.

In gasification processes using alkali metal-containing catalysts, the cost of the catalyst is an important factor in determining the total cost of the product gas. Potassium carbonate is
Relatively expensive.

Other alkali metal compounds such as potassium chloride, potassium sulfate, sodium carbonate, sodium chloride, and sodium sulfate are significantly less expensive than potassium carbonate, but these compounds exhibit a fraction of the catalytic activity of potassium carbonate. It only shows that. If the above-mentioned compounds and other abundant and inexpensive potassium and sodium compounds are effectively used as gasification catalysts, the initial investment cost of the catalyst can be substantially reduced and the amount of catalyst available It would be highly desirable to eliminate the need for costly secondary recovery techniques to reduce the amount of make-up alkaline compound required to maintain the required levels of alkaline compounds.

The present invention provides an improved method for catalytic gasification of carbonaceous feedstocks. According to the present invention, oil, petroleum residue, bituminous coal, subbituminous coal, lignite, organic waste, petroleum It has been found that the catalyst costs incurred during the gasification of coke and other carbonaceous feedstocks can be significantly reduced, while at the same time unexpectedly high gasification rates can be obtained. Laboratory tests have shown that surprisingly high gasification rates can be obtained by injecting a mixture of coal, potassium chloride or sulfate, and sodium carbonate or sulfate into the reaction zone and then gasifying the coal. Ta. These gasification rates are substantially higher than expected based on the lower activity of the individual potassium and sodium compounds compared to potassium carbonate. This is an important and unexpected finding. This is because the observed gasification rates are sufficiently high to allow mixtures of these inexpensive potassium and sodium salts to be used as gasification catalysts instead of the substantially more expensive potassium carbonate. It is from. Because of the amount of catalyst required in catalytic gasification operations, the total savings enabled by the present invention in large scale gasification plants may be significant.

Generally speaking, potassium compounds with relatively low catalytic activity compared to potassium carbonate, and stronger salts of sodium or lithium and weaker salts of sodium or lithium, which are converted to weaker salts under the reaction conditions in the reaction zone. Unexpectedly high gas velocities are obtained when the carbonaceous feedstock is introduced into the reaction zone together with a mixture of sodium or lithium compounds selected from the group consisting of: For certain relatively uncatalyzed mixtures of potassium and sodium compounds, the gasification rates obtained are such that potassium carbonate alone is introduced into the reaction zone with the feedstock in an amount that produces the same alkali metal to carbon atomic ratio as the mixture. The speed is approximately the same as that obtained when Apparently, the sodium or lithium compounds activate the less catalytically active potassium compounds, thereby exerting a substantial catalytic effect on the gasification rate of the carbonaceous feedstock.

According to the present invention, the use of a catalyst containing a mixture of inexpensive potassium and sodium compounds reduces initial catalyst costs and make-up catalyst costs while at the same time making it possible to achieve high gasification rates. The use of such mixtures also eliminates the need for costly secondary catalyst recovery operations. As a result, the present invention allows for considerable savings in gasification operations and the production of product gas at significantly lower costs than would normally be the case.

Referring now to the accompanying drawings, the method illustrated in FIG.
It is a method of gasifying organic waste or similar carbonaceous solids. Although not limited to this particular gasification method, the present invention utilizes an alkali metal compound to promote the reaction of steam, hydrogen, carbon dioxide, or similar gasifying agent with a carbonaceous feedstock and a carbide ( various fixed beds, such as those that recover coke or other solid products containing alkali metal residues;
It will be appreciated that it can be used in both moving bed and fluidized bed gasification operations. Many such operations are described in the technical literature and are well known to those skilled in the art.

In the illustrated method, a solid carbonaceous feedstock, such as bituminous coal, subbituminous coal, lignite, or the like, which has been crushed and sieved to a particle size of about 8 mesh or smaller by U.S. sieve standards, is used to prepare the coal. The system is supplied via line 10 from a plant or storage facility (not shown). The solids introduced via line 10 are fed into a hopper or similar vessel 12 from where they are passed via line 13 to a raw material preparation zone 14. The illustrated raw material preparation zones are:
A screw conveyor or similar device (not shown) powered by a motor 16 and a soluble material introduced via line 18 onto the solids as they are moved through the preparation zone by the conveyor. A series of spray nozzles or similar devices 17 for spraying the solution of the alkali metal compound and nozzles or the like 19 for introducing the steam into the preparation zone from line 20 to heat the solids and drive out the moisture. including. The alkali metal solution supplied via line 18 is mixed with soluble sodium and potassium salts or other sodium and potassium compounds as indicated by lines 22 and 23, respectively, in a mixing vessel 2.
1 and dissolved in water or other suitable solvent solution introduced through these. It is also possible to use an alkali metal solution recycled from the catalyst recovery zone via line 25 as described below. Steam is withdrawn from the preparation zone 14 via line 28, typically in a condenser or heat exchanger for recovery of heat and condensate, which can be used as make-up water or the like. (not shown).

The potassium compound introduced into the mixing vessel via line 23 is typically an inexpensive compound with relatively low catalytic activity compared to potassium carbonate. As used herein, the term "relatively low catalytic activity compared to potassium carbonate" refers to the presence of a potassium compound in an amount sufficient to produce an atomic ratio of potassium cations to carbon atoms of about 0.03 or greater. gasification rate obtained from gasifying a carbonaceous material in do. Examples of such potassium compounds include potassium chloride, potassium sulfate and similar potassium salts of strong acids. The term "strong acid" as used herein refers to approximately 1×
means an organic or inorganic acid with an ionization constant greater than 10 ^-3 .

The sodium compound introduced into the mixing vessel 21 via line 22 is typically a strong acid sodium which is temporarily or permanently converted to a weak acid salt of sodium when subjected to gasification conditions in the presence of a potassium compound. salt or the sodium salt of a weak acid. The term "weak acid" as used herein means an organic or inorganic acid having an ionization constant of less than about 1x10 ^-3 at 25°C. Examples of suitable sodium compounds that are salts of weak acids include sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium sulfide, sodium oxalate, sodium acetate, and the like. Examples of sodium salts of strong acids that can be used in combination with potassium sulfate to be temporarily or permanently converted to weaker acid salts include sodium chloride, sodium sulfate, and sodium nitrate. The practical sodium compound used usually depends on its availability, cost, solubility and the potassium compound used.

Surprisingly, when the mixture of potassium and sodium compounds described above is injected into the catalytic gasification zone together with the carbonaceous feedstock and gasified in the zone, the mixture of potassium and sodium compounds described above, when injected into the catalytic gasification zone and gasified in the zone, reacts more slowly than would normally be expected by one skilled in the art. It was found that a high gasification rate could be obtained. Apparently, when a potassium compound with low catalytic activity is activated by a sodium compound, this has a substantial catalytic effect on the gasification rate of the carbonaceous feedstock. Typically, a concentration of sodium compound sufficient to produce a sodium to potassium molar ratio of 1.0 will fully activate the potassium compound. However, in some mixtures, smaller amounts of the sodium compound can be used to activate the potassium compound without much loss of activity.

The actual mechanism by which sodium compounds activate potassium compounds in the presence of carbonaceous feedstock and under gasification conditions is not completely understood. However, it is believed that certain interactions occur between the compounds, which convert the less catalytically active strong salt salt of potassium into the catalytically active weaker salt salt. For example, the following equation would represent the reaction that occurs when the potassium compound used is potassium sulfate and the sodium compound used is sodium carbonate.

As can be seen in formulas (1) and (2), the anion bound to the potassium compound and the anion bound to the sodium compound exchange with each other to form K ₂ CO ₃ and
Na ₂ SO ₄ is produced, which is reduced to Na ₂ S under gasification conditions in the presence of carbon, hydrogen or carbon monoxide. _Na2S then undergoes ion exchange _{with K2SO4} to produce _K2S and additional _Na2SO4 , which _is also reduced to _Na2S . The net result of these reactions is that the catalytically less active K ₂ SO ₄ , a strong acid salt of potassium, is converted to the catalytically active K ₂ CO ₃ and K ₂ S, which are weak acid salts of potassium. . The Na ₂ S produced is also catalytically active and this appears to increase the total catalytic activity obtained with the original combination. K ₂ CO ₃ , which is a weak acid salt;
K ₂ S and Na ₂ S are believed to react with the acidic carbonaceous solids to form alkali metal-carbide "salts" which would be the active sites during gasification. Thus, in cases where the potassium compound is K ₂ SO ₄ and the sodium compound is Na ₂ CO ₃ , both the potassium and sodium cations complete the catalysis of the gasification of the carbonaceous solids.

If the potassium compound is potassium sulfate and the sodium compound is sodium sulfate, then
The following equation appears to represent the reaction that occurs.

In the case illustrated above, anion exchange cannot occur between K ₂ SO ₄ and Na ₂ SO ₄ . This is because the anions are of the same type. However, Na ₂ SO ₄ , which is a strong acid salt, becomes a weak acid salt under gasification conditions in the presence of carbon, carbon monoxide or hydrogen.
It is theorized that it is reduced to Na ₂ S, which then undergoes anion exchange with K ₂ SO ₄ to form K ₂ S and Na ₂ SO ₄ . The Na ₂ SO ₄ thus produced also
Reduced to Na ₂ S in the presence of carbon, carbon monoxide or hydrogen. The net result of these reactions is the production of catalytically active K ₂ S and Na ₂ S, and therefore
Similar to the examples illustrated in equations (1) and (2) above, both potassium and sodium cations complete the catalysis of the gasification of carbonaceous solids.

Equations (5) and (6) shown below appear to represent the mechanism by which potassium sulfate is activated by sodium chloride.

As can be seen from the above, potassium and sodium compounds exchange anions, thereby producing Kcl and Na ₂ SO ₄ . Na ₂ SO ₄ is then reduced to Na ₂ S under gasification conditions and in the presence of carbon, hydrogen or carbon monoxide, which undergoes anion exchange with Kcl to form catalytically active K ₂ S and catalytically inactive NaCl (which is one of the first reactants) is produced. Thus, unlike the examples illustrated in equations (1) to (4) above, only potassium cations complete the catalytic action of the gasification reaction.

As previously mentioned, any weak acid salt of sodium can be used to activate the relatively non-toxic potassium compound, but only certain strong acid sodium salts are effective for this purpose. Generally speaking, only strong acid salts of sodium can be used which are temporarily or permanently converted to weak acid sodium salts under gasification conditions and in the presence of the potassium compound to be activated. The examples illustrated by equations (3)-(6) above represent two cases of activation of relatively uncatalyzed K ₂ SO ₄ by a strong acid sodium salt that is converted to a weak acid salt. In the example exemplified by equations (3) and (4), the strong acid sodium salt Na ₂ SO ₄ undergoes reduction and is thereby permanently converted to the weak acid salt Na ₂ S. In the example illustrated by equations (5) and (6), the strong salt NaCl is converted to the weak salt _Na2S in a two-step process.
converted into. First, NaCl participates in anion exchange with K ₂ SO ₄ to form the strong salt Na ₂ SO ₄ and then 24 undergoes reduction to Na ₂ S. However, _Na2S then exchanges anions with Kcl to reform the strong salt Nacl. Therefore, this example
This represents the case where a strong acid sodium salt is only temporarily converted to a weak acid salt. An example of a strong acid salt of sodium that is neither temporarily nor permanently converted to a weak acid sodium salt in the presence of K ₂ SO ₄ under gasification conditions and therefore does not activate K ₂ SO ₄ is Na ₃ PO It is ₄ .

The total amount of sodium and potassium compounds used should generally be sufficient to provide a total alkali metal to carbon atomic ratio of greater than about 0.03:1. Generally speaking, about 5% to about 50% by weight sodium and potassium compounds are used based on the coal or other carbonaceous feedstock. about 10 to about 35
Weight percent is generally preferred. The higher the mineral content of the feedstock, the more sodium and potassium compounds usually have to be used.

Referring again to FIG. 1, the feed solids impregnated with sodium and potassium compounds in feed preparation zone 14 are withdrawn via line 30 and sent to a feed hopper or similar vessel 31. From here, they are sufficiently elevated to allow their entrainment into the stream of steam, recycled product gas, inert gas or other carrier gas that is introduced into the system via line 34. It is discharged under pressure through a star wheel feeder or similar device 32 in line 33. The carrier gas and entrained solids are
It is routed via line 35 to manifold 36 and fed to gasifier 38 via multiple feed lines 37 and nozzles (not shown). In place of or in addition to the hopper 31 and star wheel feeder 32, feed systems that may be used include parallel lock hoppers,
Mention may be made of pressurized hoppers, continuously operated vented standpipes, or other devices for raising the incoming raw solids stream to the required pressure level.

Gasifier 38 consists of a refractory lined vessel containing a fluidized bed of carbonaceous solids extending above an internal grate or similar distribution device (not shown). The solids are maintained in a fluid state within the gasifier by a mixture of steam and oxygen injected through a bottom inlet tube 39 and multiple nozzles 40 connected to the manifold 41. Sufficient oxygen is added to the steam via line 42 to maintain the fluidized bed at a temperature within the range of about 1200 to about 2000°C. Gasifier pressure is typically between about 100 and about 2000 psig. Under these conditions, the added sodium and potassium compounds have an unexpected and substantial catalytic effect on the steam gasification reaction, thereby increasing the concentration of gases consisting primarily of hydrogen, carbon monoxide, and carbon dioxide. bring about generation. Other reactions also occur,
And some methane is usually produced depending on the gasification reaction.

Gas exiting the fluidized bed of gasifier 38 passes through the upper part of the gasifier. This upper part serves as a separation zone where particles that are too heavy to be entrained by the gas leaving the vessel are returned to the bed. If desired,
The separation zone may include one or more cyclone separators or similar devices to remove relatively large particles from the gas. Gas withdrawn from the upper part of the gasifier via line 43 is sent to a cyclone separator or similar device 44 to remove large fines. The overhead gas then enters a second separator 47 through line 46 where smaller particles are removed. The gas from which the solids have been separated is taken out as overhead from the separator 47 via line 48, and the fine powder is discharged downward via depressures 45 and 49. These fines can be returned to the gasifier or sent to the catalyst recovery zone of the process, as described below. After separation of the entrained solids from the crude product gas, the gas stream can be passed through suitable heat exchange equipment for heat recovery and then sent downstream for further processing.

Char particles containing carbonaceous material, ash and alkali metal residues are continuously withdrawn from the bottom of the fluidized bed in gasifier 38 via line 50. The particles flow downwardly through line 50 in countercurrent to the flow of steam or other elutriating gas introduced via line 51. A preliminary separation of the solids is then carried out on the basis of size and density differences. Light particles containing relatively large amounts of carbonaceous material tend to be returned to the gasifier, and heavier particles containing relatively large amounts of ash and alkali metal residues are passed through line 52 to fluidized bed withdrawal zone 53. continues to flow downward. At the bottom of the withdrawal zone, steam or other fluidizing gas is introduced via line 54 to maintain the bed in a fluidized state. Water can be introduced via line 55 to cool the particles and facilitate their further processing. The withdrawal speed is determined by the throttle valve 56 of the overhead pipe 57.
is controlled by adjusting the pressure in zone 53 by. Gas from conduit 57 is transferred to conduit 58
can be returned to the gasifier via the gasifier or can be discharged via the valve 59. From container 53, the solid particles are conveyed to hopper 62 via line 60, which includes valve 61. Carbide particles recovered from the crude product gas via deplegs 45 and 49 can be combined with the carbide particles withdrawn from the gasifier by sending them via line 63 to hopper 62.

The particles within the hopper 62 contain sodium and potassium residues consisting of water-soluble and water-insoluble sodium and potassium compounds. These particles are sent from the hopper 62 via a conduit 64 to a catalyst recovery device 65. Catalyst recovery equipment typically consists of a multistage countercurrent extraction system in which particles containing sodium and potassium residues are brought into countercurrent contact with water introduced via line 66. An aqueous solution of sodium and potassium compounds is recovered from this device, which can be recycled via lines 67 and 25 to the catalyst preparation device or mixing vessel 21. The particles, from which substantially all of the soluble sodium and potassium components have been extracted, are withdrawn from the catalyst recovery device via line 68. These solids usually contain substantial amounts of sodium and potassium present in the form of sodium and potassium aluminosilicates and other water-insoluble compounds. These compounds are formed in part by the reaction of ash in coal and other feedstocks with sodium and potassium compounds added to catalyze the gasification reaction. Generally speaking, the amount of added alkali metal component is approximately
As much as 15% to 50% is converted to alkali metal aluminosilicates and other water-soluble compounds. By using a mixture of inexpensive potassium and sodium compounds according to the process of the present invention in place of expensive potassium carbonate and other well-known catalysts, water-insoluble alkali metals can be recovered by costly and complicated secondary recovery methods. The need to recover and reuse bound sodium and potassium compounds as residue is eliminated.

In the embodiment of the invention described above, the feed solids are impregnated with a solution containing a mixture of sodium and potassium compounds prior to their introduction into the gasifier 38. It will be appreciated that other methods of introducing sodium and potassium compounds into the gasification zone can be used. For example, the compound can be mixed in the solid state with carbonaceous feedstock particles and then the mixture can be sent to a gasifier. In some cases, it may be desirable to introduce the feed solids, sodium compounds, and potassium compounds to gasifier 38 by separate lines. Other methods for separately introducing the sodium and potassium compounds into this system will be apparent to those skilled in the art.

The essence of the present invention is demonstrated by the results of laboratory gasification studies showing that unexpectedly high gasification rates can be obtained by using certain combinations of sodium and potassium compounds and lithium and potassium compounds as catalysts. and further exemplify the purpose. Approximately 30 to approx. US sieve standards in all tests
Approximately 2 grams of Illinois No. 6 coal, ground to 100 meshes, was mixed with varying amounts of finely divided alkali metal compounds and combinations of such compounds. The resulting mixture was then moistened with about 1 ml of distilled water and pyrolyzed in a retort under an inert nitrogen atmosphere at about 1400 ml for about 15 minutes. The obtained carbide (approximately 0.2 ~
(containing about 0.5 g of carbon) is then processed in a laboratory bench-scale gasifier at about 1300 〓
steam gasification at a humidity of 500 mL and essentially atmospheric pressure. The gasification rate obtained for each char sample was measured. The amount of carbon present was determined by incinerating the ungasified carbide, and the alkali metal cation to carbon atomic ratio was then calculated. The results of these tests are shown in Figures 2-10. In all cases, the gasification rate is % carbon present per hour over the interval 0 to 90% carbon softening rate.
expressed as the weight average rate of softening.

FIG. 2 shows steam gasification rate data obtained from char impregnated with varying concentrations of potassium carbonate, potassium sulfate, sodium carbonate, and mixtures of potassium sulfate and sodium carbonate. In Figure 2, the relatively expensive potassium carbonate produces a gasification rate that is significantly greater than the less expensive potassium sulfate and sodium carbonate, and is therefore significantly more active than either of the latter two compounds. It turns out that it is a gasification catalyst.

The dash line in Figure 2 indicates the gasification rate expected to be observed if a mixture of sodium carbonate and potassium sulfate in which sodium and potassium are equimolar (Na/k mole = 1.0) was used as a catalyst. represents. The predicted gasification rate for such a mixture yielding an atomic ratio of 0.066 alkali metal cations per carbon atom was calculated as follows.
An observed rate of approximately 9.0% carbon/hr for a potassium sulfate concentration resulting in an atomic ratio of 0.066 potassium cations/carbon atoms to 0.066 sodium cations/hr.
Add the measured value of approximately 51% carbon/hr for the sodium carbonate concentration resulting in the atomic ratio of carbon atoms, and divide the resulting value of 60% carbon/hr by 2 to give the expected value of 30% carbon/hr. Ta. Then, this speed is
0.033 of the cations are potassium cations and the other 0.033
is plotted against the atomic ratio of 0.066 cation/carbon atom, which is the sodium cation. The predicted gasification rates for mixtures of sodium carbonate and potassium sulfate where the sodium and potassium were equimolar but yielded other values of alkali metal cation to carbon atomic ratios were calculated in the same manner as above.

As can be seen in Figure 2, the actual gasification rate observed using a mixture of potassium sulfate and sodium carbonate is represented by the dash line, which can be obtained with an equal concentration of potassium carbonate. It was significantly higher than the predicted speed, which is close to the possible speed.
The observed gasification rate for a potassium and sodium cation/carbon atom atomic ratio of 0.066 was 83% carbon/hr compared to the expected 30% carbon/hr. Additionally, the observed rate of 83% carbon/hr for a mixture at an atomic ratio of potassium and sodium cations/carbon atoms of 0.066 is greater than the 9.0%/hr obtained with potassium sulfate at an atomic ratio of potassium cations/carbon atoms of 0.066. Much larger than hr,
and 51% carbon/hr obtained with sodium carbonate at a sodium cation/carbon atomic ratio of 0.066.
greater than. In view of the above, the gasification rates obtained using a mixture of potassium sulfate and sodium carbonate as a catalyst are surprising and unexpected.

The data shown in Figures 3-5 show that surprisingly high gasification rates can also be obtained using potassium sulfate in combination with various sodium salts other than sodium carbonate. Figure 3 shows
We show that unexpectedly high rates can be obtained using a mixture of potassium and sodium sulfate with equimolar potassium and sodium as gasification catalysts.
Figure 5 shows the same for a mixture of potassium sulfate and sodium nitrate with equimolar potassium and sodium. In both figures, the speed expected by one skilled in the art is represented by the dash line, which was calculated as described above with respect to FIG. FIG. 4 shows that surprisingly high gasification rates are obtained using a mixture of potassium sulfate and sodium chloride with equimolar potassium and sodium. In FIG. 4, the gasification rates for potassium sulfate alone and sodium chloride alone are on the same line. Therefore, this line also represents the expected gasification rate for a mixture of two salts with equimolar potassium and sodium.

Figures 6 and 7 show that catalysts consisting of mixtures of potassium chloride and one of various inexpensive sodium salts result in higher than predicted gasification rates when the catalyst concentration is above a certain value. Illustrate this. Figure 6 shows that potassium and sodium are surprisingly high when using an equimolar mixture of potassium chloride and sodium carbonate in concentrations sufficient to yield an atomic ratio greater than about 0.08 alkali metal cation/carbon atom. Show that speed can be obtained. Figure 7 shows the same for a mixture of sodium chloride and sodium sulfate with equimolar potassium and sodium. As in the previous figure, the predicted gasification rate is represented by the dash line, which was calculated as described with respect to FIG.

FIG. 8 illustrates that a catalyst consisting of a relatively uncatalyzed mixture of potassium and lithium salts (instead of sodium salts) also provides unexpectedly high gasification rates. In FIG. 8 it can be seen that surprisingly high gasification rates are obtained when the carbide is gasified in the presence of a mixture of potassium and lithium sulfate with equimolar potassium and lithium. As in the previous figure, the dart line represents the gasification rate as expected by one skilled in the art.

FIG.
The gasification rate obtained when No. 6 coal carbide is gasified is shown. In all cases, potassium sulfate was present in an amount such that the atomic ratio of potassium cations to carbon atoms was within the range of about 0.051 to about 0.057. The abundance of a particular sodium salt was varied over a range such that the ratio of sodium to potassium cations present per carbon atom was within the range of 0.25 to 1.0. This ratio (Na/k) is shown near each point plotted on the figure. For comparison purposes, a rate of 8% carbon/hr obtained using potassium sulfate alone (Na/k=0) is also shown in the figure.
The plotted data shows that for each combination of potassium sulfate and one of the three sodium salts, a very small amount of sodium salt (Na/k=0.25)
It can be seen that the presence of sodium salt resulted in a significant increase in the gasification rate over that of zero concentration of sodium salt. The gasification rate continued to increase as the amount of sodium salt in the mixture was increased to a sodium to potassium atomic ratio of 1.0.

FIG. 10 is a plot similar to Example 9, except that the gasification rates plotted are for catalysts consisting of mixtures of potassium chloride and varying amounts of sodium carbonate. For comparison purposes, the rate of 18% carbon/hr using potassium chloride alone (Na/k=0) is also shown in the figure. As can be seen in the drawing, a small amount of sodium carbonate (Na/k = 0.26~
0.49) does not substantially increase the gasification rate. The rate of gasification increases rapidly only when the amount of sodium carbonate in the mixture is sufficient to provide a sodium to potassium atomic ratio of 1.0 or greater. In view of the data shown in Figures 9 and 10, it appears that small amounts of certain sodium compounds catalytically activate potassium sulfate, which has low catalytic activity;
On the other hand, it can be concluded that a larger amount is required to activate potassium chloride, which has a lower catalytic activity.

From the above, it can be seen that the present invention makes it possible to use a mixture of inexpensive alkali metal salts as a catalyst and at the same time obtain gasification rates almost as high as can be obtained by the use of expensive potassium carbonate. It will be apparent that a method for gasifying carbonaceous materials is provided. As a result, the total cost of product gas can be substantially reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic flowchart of a coal gasification process carried out in accordance with the present invention. Figure 2 shows that unexpectedly high gasification rates can be obtained by using a mixture of potassium sulfate and sodium carbonate with equimolar potassium and sodium to catalyze the gasification of carbonaceous materials. It is a plot.
Figure 3 shows that unexpectedly high gasification rates are obtained by catalyzing the gasification of carbonaceous materials using a mixture of potassium and sodium sulfate with equimolar potassium and sodium. It is a plot. Figure 4 is a plot showing that unexpectedly high gasification rates can be obtained by catalyzing the gasification of carbon materials using a mixture of potassium sulfate and sodium chloride with equimolar potassium and sodium content. It is. Figure 5 shows that unexpectedly high gasification rates are obtained by using a mixture of potassium sulfate and sodium nitrate with equimolar potassium and sodium to catalyze the gasification of carbonaceous materials. It is a plot. Figure 6 shows
1 is a plot showing that unexpectedly high gasification rates can be obtained by using a mixture of potassium chloride and sodium carbonate with equimolar potassium and sodium to catalyze the gasification of carbonaceous materials. Figure 7 shows that unexpectedly high gasification rates are obtained by using a mixture of potassium chloride and sodium sulfate with equimolar potassium and sodium to catalyze the gasification of carbonaceous materials. It is a plot. FIG. 8 is a plot showing that unexpectedly high gasification rates can be obtained by using a mixture of potassium and lithium to catalyze the gasification of carbonaceous materials. FIG. 9 is a plot showing that the addition of small amounts of various sodium salts activates relatively uncatalyzed potassium sulfate, thereby rapidly increasing the rate of gasification of carbonaceous materials. Figure 10 shows that relatively uncatalyzed potassium chloride catalytic gasification activity can be substantially improved by adding sodium carbonate in an amount sufficient to produce a sodium to potassium molar ratio of 1.0 or greater. This is the plot shown. In FIG. 1, reference numerals representing main parts are as follows. 14: Raw material preparation zone, 21: Catalyst preparation zone, 38: Gasifier, 53: Fluidized bed withdrawal zone, 65: Catalyst recovery device.

Claims (1)

Claims: 1. Potassium salts of organic or inorganic acids having an ionization constant greater than about 1×10 ^-3 and strong salts of sodium or lithium and sodium or lithium salts which are converted in the reaction zone to weak acid sodium or lithium salts. contacting the carbonaceous feedstock under gasification conditions with a catalyst selected from the group consisting of weak acid salts of lithium and comprising a mixture with a sodium or lithium compound in an amount sufficient to activate said potassium salt; the potassium salt and the sodium or lithium compound are present in a concentration sufficient to produce a sodium or lithium to potassium atomic ratio of at least about 0.25, and the total amount of the potassium salt and the sodium or lithium compound is greater than 0.03:1. A process for the catalytic gasification of a carbonaceous feedstock, characterized in that the atomic ratio of potassium and sodium or lithium to carbon in the carbonaceous feedstock is sufficient to provide. 2. The method of claim 1 further characterized in that the carbonaceous feedstock comprises coal. 3. The method according to claim 1 or 2, further comprising impregnating the carbonaceous feedstock with an aqueous solution of a potassium salt and a sodium or lithium compound prior to introducing the carbonaceous feedstock into the reaction zone. Method. 4. Claims 1 to 3 further characterized in that the potassium salt consists of a salt selected from the group consisting of potassium sulfate, potassium chloride, and mixtures thereof.
The method described in any of the paragraphs. 5. Claims 1 to 3 further characterized in that the sodium compound is selected from the group consisting of sodium carbonate, sodium bicarbonate, sodium sulfate, sodium hydroxide, sodium chloride, sodium sulfide, sodium nitrate, and mixtures thereof.
The method described in any of the paragraphs. 6. A method according to any one of claims 1 to 5, further comprising gasifying the carbonaceous feedstock with steam. 7. A method according to any one of claims 1 to 5, further comprising gasifying the carbonaceous feedstock with hydrogen.