Catalytic coal gasification by utilizing chlorides

[73] Assignee: Tohoku University, Sendai, Japan
[21] Appl. No.: 105,351
[22] Filed: Oct. 6, 1987

[30] Foreign Application Priority Data

Oct. 9, 1986 [JP] Japan 62-239358

[51] Int. CI.* C10J 3/14; C10J 3/16

[52] U.S. a 48/202; 48/206;

48/210

[58] Field of Search 48/197 R, 202, 203,

48/206, 210, 209; 252/373

[56] References Cited

U.S. PATENT DOCUMENTS

4,069,304 1/1978 Starkover et al 48/202

4,092,125 5/1978 Stanbaugh et al 48/210

4,200,439 4/1980 Lang 48/202

4,204,843 5/1980 Neavel 48/210

4,318,712 3/1982 Lang et al 48/202

4,500,323 2/1985 Siegfried et al 48/202

4,508,543 4/1985 Peter 48/202

4,551,155 11/1985 Wood et al 48/202

4,558,027 12/1985 McKee et al 48/197 R

FOREIGN PATENT DOCUMENTS 2530600 1/1977 Fed. Rep. of Germany 48/202

OTHER PUBLICATIONS

Johnson, Kinetics of Coal Gasification, John Wiley & Son, 1979, pp. 271-278.

"Catalytic Activity of Potassium Halides in Water Vapour Gasification of Graphite", by Klaus J. Huttinger et al., Fuel, 1984, vol. 63, Jan., pp. 9-12. "Water Vapour Gasification of Carbon-Improved Catalytic Activity of Potassium Chloride Using Anion Exchange", by Klaus J. Huttinger, et al, Fuel, 1985, vol. 64, Apr., pp. 486-490.

"Anion effects in Alkali-Catalysed Steam Gasification", Fuel, 1986, vol. 65, Oct., pp. 1324-1329. Hashimoto, et al., "Relation Between the Gasification Rate of Carbons Supporting Alkali Metal Salts and the Amount of Oxygen Trapped by the Metal", Fuel, vol. 65, pp. 489-494 (Apr. 1986).

Primary Examiner—Peter Kratz

Attorney, Agent, or Firm—Fleit, Jacobson, Cohn & Price

A process of catalytic coal gasification characterized by mixing an inexpensive, low rank coal with an aqueous solution of inexpensive, widely existing alkali metal or alkaline earth metal chlorides, such as Nacl, KC1, or the like; adding a pH adjuster such as ammonia to the resulting mixture to adjust pH to 5 —12, whereby an ion exchange is effected between said metal and hydrogen in the coal, thereby loading only metals as a catalyst on the coal; washing the coal with water to remove chloride by-products; and running steam onto the catalystloaded coal at high temperatures and high pressures.

3 Claims, 2 Drawing Sheets

1

CATALYTIC COAL GASIFICATION BY
UTILIZING CHLORIDES

BACKGROUND OF THE INVENTION 5

1. Field of the Invention

The present invention relates to a process of catalytic gasification of coal by using a highly active alkali metal or alkaline earth metal catalyst for coal gasification, 1Q loaded onto a coal, which catalyst is prepared by mixing an inexpensive, low rank coal, such as lignite, brown coal, subbituminous coal and the like, with an aqueous solution of an inexpensive salt such as NaCl, KC1 and the like, as a starting material for the catalyst, and only ^ the alkali metal or alkaline earth metal is introduced into the coal as the catalyst.

2. Description of the Prior Art

Coal gasificatiion techniques have been developed for a long time and utilized in the manufacture of syn- 20 thetic gases and hydrogen gas. Recently, processes of catalytic coal gasification have been actively developed, which are directed to an increase in efficiency of gasification. The processes of catalytic coal gasification promote gasification reactions catalytically, wherein a 25 catalytically active material fed into a gasification furnace together with a coal, is interposed between the coal and a gasifying agent.

There have been reported various substances, such as alkali metal salts, alkaline earth metal salts, VIII group 30 transition metals, etc., which promote coal gasification reactions. Particularly, it has been known that alkali metal carbonates, such as K2CO3, ... and the like, have a very prominent catalytic effect on steam gasification reactions. In C.C.G. processes that the EXXON 35 group is developing, the steam gasification of coal is effected at 700° C. using K2CO3 as a catalyst. However, snce the K2CO3 catalyst reacts with mineral matter in the coal, the complete recovery of the catalyst from reaction residues is substantially impossible. This would be a big problem from an economical point of view. Accordingly, attention has been paid to preparation of highly active gasification catalysts, using inexpensive materials for the catalysts. 45

Because of low prices and existence in large quantities, alkali chlorides such as NaCl, KC1 and the like, therefore, may be preferable as materials for the catalysts. However, the use of these chlorides as a coal gasification catalyst presents two major problems. One 50 is the inactivity of these chlorides for gasification reaction, and the other is corrosion of gasification apparatuses caused by hydrogen chloride generated from said chlorides. Therefore, it is necessary to activate the inactive chlorides to provide good gasification catalysts and 55 further to remove chlorine in advance, so that an appropriate catalyst loading method to be used therefor has been required to be developed.

SUMMARY OF THE INVENTION

60

An object of the present invention is to provide processes of catalytic coal gasification, utilizing chlorides, which processes comprise using alkali chlorides, as a material for catalyst, which are inexpensive but are inactive substance per se for coal gasification reactions, 65 and removing chlorine from the chlorides in a catalyst preparation step, to prepare highly active gasification catalysts.

2

Further object of the present invention is to manufacture synthetic gases and town gases by effective coal gasification processes.

The above objects can be achieved by a catalytic coal gasification process by utilizing chlorides, in accordance with the present invention, which process is characterized by mixing a coal with an aqueous solution of a chloride of at least one metal selected from the group consisting of alkali metals and alkaline earth metals; adding a pH adjustor to a mixture of said coal and the chloride to maintain a pH value in the range between 5 and 12, whereby an ion exchange is effected between said metal(s) and hydrogen in the coal, thereby introducing only said metal(s) as a catalyst into the coal in an amount of 1 ~ 10% by weight based on the coal; washing the coal with water to remove chlorides secondarily produced by said ion exchange; and running a gasifying agent such as steam at a temperature of 500° ~ 800° C. under a pressure of 1~100 atm. onto the coal loaded with said catalyst and dechlorinated, to effect a catalytic coal gasification reaction.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which:

FIG. 1 shows a graph of coal conversion against reaction time in the present invention wherein NaCl and KC1 were used as a starting material for the catalyst and, ammonia and Ca(OHh werre used as a pH adjuster; and

FIG. 2 is a graph illustrating a relation between Naloading amount and reaction rate in a specimen prepared by using NaCl according to the present invention.

DETAILED DESCRIPTION OF THE
INVENTION

The general feature of the present invention is to prepare highly active coal gasification catalysts by introducing only alkali metals or alkaline earth metals into the coal, using inexpensive alkali metal or alkaline earth metal chlorides, such as NaCl, KC1 and the like, as a starting material for the catalysts. Now, when an ion exchange occurs between the above chlorides and the coal in an aqueous solution, the pH of the solution is so lowered that the ion exchange reaction is not allowed to proceed further. So, as a pH adjustor, ammonia or Ca(OH)2 is added gradually in the beginning and/or intermediary stage so as to maintain the pH of the catalystloaded solution between about 5 and 12.

The ion exchange and neutralization reactions in the present invention are represented by the following chemical reaction formulae.

lCOALt-COOH+NaCl-^HCl+|COAL|—COONa (1)

|COALt-OH + NaCl—HCl +|CO Al)—O—Na (2)

... ... ... (3)

2HCl + Ca(OH)2—CaCl2+2H20 (4)

By the ion exchange between H of —COOH or —OH groups in the coal and Na in NaCl, the Na is introduced into the coal, producing HC1. The producing HC1 reacts with ammonia, Ca(OH)2 or the like, added as a pH adjustor, yielding NH4CI, CaCh or the like which partly adheres on and around the coal. Ac