NO811314L - PROCEDURE FOR CONVERSION OF COALS, Peat and THREE TO HYDROCARBON MATERIALS - Google Patents

Description

The present invention relates to further develop-

ling of a method described in application no. 063824 submitted on August 6, 1979, application no. 114,207 submitted on January 22, 1980 and application no. 140,604 submitted on April 15, 1980.

In the first-mentioned application, a method has been described for producing an alkali metal reagent and a reaction based on this reagent with oxygen, nitrogen and sulfur in coal.

Application no. 1114.207 describes the application of the method described in the first-mentioned application on coal of different types and peat, as well as the use of water or steam in the method, which can be used either in portions or continuously. Application No. 114,207 also contains a description of different conditions, so that a product mixture can be obtained by using different temperatures, reagents, types of coal, in addition to different reaction steps. In application no. 114,207, an addition of sulfur to stabilize a reagent as a less hydrolysed polysulphide is further described.

Application no. 140,604 describes a number of methods for the production of reagents, stabilization of these reagents by using hydrogen sulphide in the hydro-treating carbonaceous material, as well as stepwise reactions. It has now been found that, in addition to stabilizing the reagent for coal and peat, an addition of hydrogen sulphide will have surprising advantages based on the difference in chemical composition of coal or peat and the carbonaceous materials described in the present application.

The present invention relates to the further development of the inventions described in the above-mentioned applications and relates to the conversion of coal into different component parts, either essentially gaseous components or a variable ratio between gaseous and liquid components, and this also includes essentially liquid products , and where a recovery of a reagent and hydrogen sulphide which is provided as part of the conversion process is carried out. The invention further describes the conversion of these gaseous components into other distillates, and more particularly the invention concerns the conversion of coal into desired conversion products such as hydrocarbons in liquid or gaseous form by reacting coal in one or more steps with a special reagent, which can be the same or different for every other step, but in each step, the reagent is present in the presence of water or steam as well as hydrogen sulphite. The procedure is carried out at low to moderate temperatures and between atmospheric pressure and pressure of less than 0.4 kg/cm 2 .

Furthermore, the invention relates to the conversion of coal into various preselected components, either essentially gaseous components, gas or liquid components or essentially liquid components by means of specific reagents, whereby coal or peat: in the presence of a reagent, water, steam and hydrogen sulphide and optionally sulphur, is converted into usable and valuable decomposition materials or compounds of coal or peat. Said products are either essentially gaseous hydrocarbons obtained in a single-step reaction, or essentially liquid hydrocarbons obtained in a single step, or gaseous and light, liquid products (by the term "light" is meant low-boiling liquids) from a single step. These products can then be reacted in one or more further steps in the presence of various reagents, steam and hydrogen sulphide to produce liquid distillates.

At high temperatures, said coal in the presence of said reagent, hydrogen sulphide and steam, can also produce certain amounts of hydrogen.

It is well known that liquid and gaseous hydrocarbon sources, such as petroleum and natural gas, are depleted very quickly, and that today intensive research is being carried out in order to be able to meet the future need for other types of energy, starting materials or chemical compounds. One of the most readily available sources of hydrocarbon materials is coal. However, until now there has been no easy process by means of which hydrocarbons could be produced from coal without large capital investments. Although various methods are known for converting coal at high temperatures, e.g. above 600°C, and at high pressures e.g. above 25 atmospheres, for the gasification of coal, so far no low-temperature, low-pressure process has been available that can readily convert coal into hydrocarbon components.

In connection with the present invention, the following patents have been consulted: U.S. Patent Nos. 1,300,816, 1,413,005, 1,729,943, 1,904,586, 1,938,672, 1,974,724, 2,145,657, 2,950,245, 3,112,257, 3,185,641, 3,252,378, 3,252,378, 378 . 3,944,480, 3,960,513, 3,957,503, 4,003,823, 4,007,109, 4,018,572, 4,030,893, 4,057,422, 4,078,917, 4,119,528, 4,147,611, 4,157,612,4,145 717, 4,160,721, and 4,210,526.

In connection with the present invention, the following literature references have been reviewed: Letoffe, et al., Determination des Enthalpies de Formation des Polysulfures de Potassium, Journal de Chimie Physique, 71, pp 427-430, 1974;

John S. Thomas and A. Rule (other articles in this series are described by Thomas and Riding)

The Polysulfides of the Alkali Metals, Journal Chemical Soc, Part 3 pp 1063 et seq., 1973;

Blitz and Wilke-Dorfurt, Z^. Inorg. Chem., vol. 48, pp 297, 1906 (see also Ber., 53, pp 43, 1905);

van Krevelen, etaål., Fuel, 38, 256, 1959,

B. K. Mazumdar, et al., Fuel, 41, 121, 1962;

Hugot, Ann. Chim Phys., 21, 72, 1900;

W. Klemm, Z. Anorg. Chem., pp. 241, 281, 1939;

F.W. Bergstrom, J. Amer. Chem. Soc, 147, 1926;

F. Feher and H. Berthold, Z. Anorg. Chem., pp. 247, 1953; Thomas and Rule, J. Chem. Soc., 2819, 1914;

R. L. Erbeck, Dissertation. Abstract, Ann Arbor, Mich. 3254,

21, 1961;

Renegade and Costeanu, Bull, soc. Chim., 15, 721, 1911; Sabbatier, Ann. Chim. Phys. 22, 5, 1881;

Marrony, J. Chim. Phys., 56, 214, 221, 1959;

MMe Aline Auroux, CR. Ac ad-. Soc. Paris, 274 ppl297 to 1300, March 197 2;

Kuster und Herberlein "Beitrage zur Kenntnise der Polysulfide<1>Z. anorg Chem., pp 53-84, Nov. 1904.

It has now been found that when coal is treated with

a special reagent, it can be converted in the presence of this reagent and in the presence of water and/or steam and hydrogen sulphide into various hydrocarbon fractions which are either essentially gaseous with from one to five carbon atoms (C1 to C1), e.g. , methane, ethane, ethene, etc., or essentially everything

in liquid distillates or in a ratio between these types of fractions as required. Hydrogen is also produced.

At higher temperatures, gaseous hydrocarbons will essentially be produced, and when a different reagent is used in a different reactor, the gaseous hydrocarbons in the presence of steam or hydrogen sulphide can be further reacted so that other hydrocarbons can be obtained either in liquid or gaseous form. It has also been discovered that by changing the reagent and using vane-free and eutectic mixtures of sulphides as explained in more detail below, the above conditions can be reversed.

It has surprisingly been found that a hydrogen sulphide addition is significantly more advantageous than a sulfur addition as described in previous applications, because the hydrogen sulphide stabilizes the reagent more effectively and helps in the conversion of the thiosulphate to the tetrathionate (and 2e) so that 2 thiosulfations are formed.

There is some degradation of KHS to ^S

in the presence of water. This degradation is partial. When hydrogenating coal, both KHS and K2S should thus be present during the reaction. When sulfur is added, a less hydrolyzed and consequently a

more water-stable polysulphide, e.g. potassium pentasulfide. Hydrogen sulfide not only improves stabilization, but also lowers the amount of reagent required.

It has also been found that when mixtures of alkali sulphides are reacted, these can be added in the liquid state to coal to facilitate the reaction, e.g. as mixtures of polysulphides or hydrates.

When K^S and various polysulphide versions of this compound are reacted with coal, they will preferentially attack the oxygen, sulfur and nitrogen in the coal in a bound form so that these components are taken out of the coal. As derivative hydrocarbon components are formed in the presence of said reagent, steam or water, as well as hydrogen sulphide, the breaking of the bond will give different coal constituents and the said abstraction of oxygen, nitrogen and sulphur, make it possible to introduce hydrogen from water or hydrogen sulphide whereby one gets the formation hydroaromatic, aromatic and short-chain aliphatic compounds. The degree of attack on

the various components can be controlled so that you get a product that is essentially a gas or a product that is essentially a liquid, based on the reagents used, as well as the operating conditions used.

The invention is illustrated by means of two drawings, where: Figure 1 schematically shows hydrogen sulphide recovery from a system for the recovery of gaseous compounds.

Once the desired operating temperatures have been reached and hydrogen sulfide or steam and hydrogen sulfide have been introduced into the system, an inert gas such as nitrogen or helium, which was first used to purge the system of oxygen, will no longer be necessary. Hydrogen sulphide can then be introduced through the steam line.

Figure 1 is a schematic representation of a system for recovering hydrogen sulphide gas. A reactor 22, typically with a temperature from 3 50 to 390°C is added coal, a reagent in liquid form, water, in the form of steam and hydrogen sulphide gas. A cooling jacket 24 located around the cooler facilitates the cooling of the reaction gases. The first and heavier products are recovered from the bottom part 27 of the cooler. The gaseous products are sent to vessel 30, where you have water and alkanol (typically methane or ethane). Vessel No. 30 receives water or alkanol from the reactor when a reagent dissolved in an alkanol is used. The mixture of water and alcohol in vessel 30 is kept below the boiling point of the mixture and the lighter gases will pass as such and this applies, among other things, to C, to C,., as well as hydrogen sulphide.

In vessel 31, the contents are cooled to approx..-35°C, and at this temperature liquid and C,.-compounds will be removed. Although most of and C,. the fractions are removed in vessel 31, but some will be carried over to vessel 32 where these are removed at -30°C with the C_ fraction in ethanol or methanol. A glass disc 33 removes any remaining fog from these components. At this stage, essentially only r^S and and C^ fractions will be present in the gas stream, which is then fed into a vessel containing KOH and alcohol, typically ethanol and methanol in water solution. Hydrogen sulphide will recreate the reagent that is collected as a precipitate, while the light fractional gases, i.e. total and fractions, will pass through. About 97% or more of said H2S is recovered as a reagent component and can be used again. No I^S is vented to the atmosphere. The alcohol-water fraction is vented from vessel 30 and is used to replace the alcohol taken out from vessel 3 5. However, this mixture must be cooled in the heat exchanger 36.

As mentioned earlier, the hydrogen sulphide can

is fed into the reactor as a separate stream or together with the steam. When the hydrogen sulphide is supplied separately, this happens at a temperature of 135°C or above, or at 170-190°C when it is mixed with steam. Typically, hydrogen sulphide will be used added and supplied together with the steam. Steam is not introduced into the reaction vessel before removing a methanol-water mixture used to introduce the reagent, because the water-methanol mixture will maintain the temperature at a

specific temperature range during this distillation. Hydrogen sulphide is present from the very beginning of the reaction.

After adding the steam or steam and continuing the addition of hydrogen sulphide, different lignites and sub-bituminous coals, depending on their composition, will give different distillation points for the production of significant quantities of gaseous hydrocarbons.

Gas production increases significantly when you reach 3 60°C, and at final temperatures between 380°C and 4 50°C there is very rapid gas production and some hydrogen is also produced. At a temperature between 360 and 380°C, carbonyl sulphide is also produced. In sub-bituminous coal, e.g. 4.7% by weight of the total hydrocarbon gas be carbonyl sulphide. When hydrogen sulfide is used and all other conditions are as before, carbonyl sulfide production appears to be suppressed.

Without being bound to one or more particular theories, it is assumed that the reaction via the water and the hydrogen sulphide molecules produces hydrogen which reacts with the coal when it is deoxygenated, desulphurised or denitrogenised. It is thus necessary in the present invention that oxygen is present in the coal, but advantages are also obtained when sulfur and nitrogen are present in the coal in the form of organic sulfur or nitrogen compounds. Better quality coal, e.g. bituminous coal, is not so easy to convert into gaseous hydrocarbons, although this can be done by suitable modification of the reaction conditions.

The present invention further relates to lignite

and sub-bituminous coal gasification, but all types of coal can be gasified or processed into liquid products, even wood in the form of tiles can be gasified. Furthermore, other cellulose-containing materials (cellulose, lignite, sugar, etc.) can be converted into gaseous and liquid products.

An anthracite coal with a content of 92% carbon can, after being partially oxidized, be converted into liquid and gaseous reaction products.

If the potassium in the coal ash is converted to hydrosulphide, there will be no loss of potassium hydrosulphide, and you will thereby obtain a very favorable reagent balance for the entire reaction, whether this happens in portions or continuously.

With hydrogen sulphide stabilization of the reagent, one can lower

the amount of reagent used, and excess sulfur and potassium from the coal is used, e.g. for said reagent, or for the production of hydrogen sulphide.

However, it must be emphasized that sufficient quantities of sulphur, hydrogen sulphide, hydrosulphide or polysulphide must be present to take up the sulfur that is secreted from the reagent or to take up oxygen or sulfur from the coal during deoxygenation, thereby preventing the secreted the sulfur dehydrogenates the coal at tempera-

trips above 17 5°C. Furthermore, the various reagents must be able to be maintained above 3 25°C, as a temperature increase above this level will result in a weak dehydrogenation of coal by means of molten alkali metal hydroxides. As the sulfur produces a formation of polysulfides and the alkali polysulfide is less hydrolysed with increasing sulfur content, the decomposition of the hydrolysis product that would otherwise occur due to the steam or other water present is prevented. However, hydrogen addition will provide the best stabilization, as explained below.

The hydrogen sulphide which is developed by the addition of elemental sulfur to the alkanol solvent

the formation of alkali metal hydrosulfide and the reaction between the sulfur replaced by oxygen during the conversion of coal to hydrocarbon compounds is used to form additional alkali metal hydrosulfide from the alkali metal hydroxide recycled in the process. Hydrogen sulphide becomes.however

also added to the reactor to stabilize the reagent, and the amount may therefore be greater than what is needed in the reaction.

As some potassium hydrosulfide was decomposed after hydrolysis, into potassium hydroxide and hydrogen sulfide.

This potassium hydroxide gives a medium at temperatures above

360°C and higher, whereby the calcium carbonate from the limestone (from the ash in the coal) reacts with the potassium sulphate (from reagent residue) so that calcium sulphate and a mixture of potassium hydroxide and potassium carbonate are formed. The potassium content in the coal ash was also extracted in the hydroxide form.

As shown above, steam was used at a temperature which is the same as that at which the reaction is to be carried out, i.e. this temperature depends on the coal type and level of decomposition as well as the desired products. Water that may be present in the coal can also be a water source and/or a steam source.

As the amount of sulfur in the reagent increases, i.e.

from sulfur in the coal and from added elemental sulfur or from the hydrogen sulphide, the reaction temperature is lowered. Thus, a reaction temperature of 380°C is lowered to 350°C, when e.g. the sulfur balance is representative of a theoretical compound for K2S3' and this is then maintained during the reaction. When this is the case, larger molecules are produced, e.g. pentane,1 such as isopentane and pentane.

The quality of the coal will affect the composition of the distillate, and the higher the quality of the coal, the higher the production of the liquid distillate will be under the same conditions, e.g. when using the theoretical K2S3 compound at the same temperature conditions.

When the temperature varies, the product composition will of course also change. Furthermore, as stated above, the amount of sulfur in the reagent can be changed, and this in turn will cause changes in the product composition.

One can thus vary the temperature, sulfur content in the reagent, the use of mixtures of reagents, e.g. dissolved forms or in the form of liquids, quality of coal, as well as using a recycling of alcohol-absorbed distillates to obtain the desired products.

The above mentioned variations can be carried out

using the following parameters: temperatures up to

425 to 4 50° but the distillation starts at 40 to 50°£, the sulfur content of the reagent (e.g. for potassium) K^ S but the sulfur content can go up to K„SC, sulfur or hydrogen sulphide addition, mixtures of these reagents, liquid or solid states of the reagents, one can contact a product stream with a different composition of reagents, this includes hydrogen sulphide, as well as quality of coal, (preferably from lignite to bituminous coal). When the method is applied to anthracite, the results are less favorable, although a distillate can be obtained at +380°C by using a reagent such as K^S^. Partial oxidation of high-quality coal will also give better results.

Furthermore, the amount of recycling can also be varied. The product composition can be up to approx. 280°C, is pressed against a composition which essentially gives liquid distillates with boiling points below 180°C. As the reaction temperature rises to 310°C, paraffin distillates will be formed when using the above-mentioned recycling of alcohol to the reaction vessel. As mentioned earlier and also under this recycling condition, water, i.e. steam at a temperature of approx. 135°C (and above) and hydrogen sulphide be present in order to get a satisfactory and beneficial reaction?

When starting the process at room temperature conditions (and raising the temperature), sulfur and preferably hydrogen sulfide is added to the coal or to the reagent to achieve the desired sulfur content in the reagent.

Under these conditions, the f^S formed in the system during the reaction between sulfur and the reagent will be removed from the gas flow and the washing system and recreate the reagent as shown in figure 1. As the temperature rises, and especially when steam is not broken, then any hydrogenation of the coal will occur due to the water content in the coal or the reagent. At approx. 13 5°C steam should be added if light distillates are desired. Typically, however, steam will be added at a temperature when a hydrate of the reagent starts and converts itself to a lower hydrate. For potassium-based reagent, a steam addition temperature will be approx. 170°C.

As oxygen is removed as well as nitrogen and organic sulphur, water or, to a lesser extent, also hydrogen sulphide (continuously produced by contact between the water and the reagents) give hydrogen to the coal in the positions where the coal is deoxygenated, desulphurised or denitrogenised, and the nitrogen will come comes out essentially as ammonia, while the sulfur comes out in the form of an alkali polysulphide and at lower temperatures it will form a mercaptan with the alkanol solvent. The mercaptans are absorbed in alcohol and in the KOH-alcohol solution. This overall reaction takes place through a reduction of hydrogen sulphide gas to sulfur and water, and a subsequent reaction between the sulfur and KOH to potassium thiosulphate and potassium sulphide. The potassium sulphide

can then take additional sulfur from hydrogen sulfide to form potassium polysulfide, and these are reagents used during the reaction.

The hydrocarbon composition, i.e. the gaseous fractions obtained at different temperatures, can be further processed in other reactors with other reagents, e.g. one with a higher sulfur content and at a lower temperature than in the first stage, where the reaction temperature is from 340 to 390°C. In the next stage, e.g. the temperature should be between 280 and 340°C with increasing sulfur content in the reagent.

In a third step, the temperature can be from 225 to 280°C or from 180 to 225°C. As the dehydrogenation reaction competes with the hydrogenation reaction, an increasing sulfur content in the reagent and the presence of the sulfur will result in a dehydrogenation of the product stream which is initially gaseous. This gas stream can then be treated to achieve the desired product composition, e.g. API number for a preselected product. In other words, the first gaseous products can be converted into products according to need.

As mentioned earlier, the above method can be improved by adding hydrogen sulphide to the reagent during the coal or coal product hydrogenation step, i.e. alkali metal sulphides, mixtures of sulphides, e.g. in hydrated form. The addition of hydrogen sulphide appears to keep the reagent in a stable state, so that the reaction as soon as it is started with a particular reagent or reagent mixture will give, with little variation from the same starting material, when all other conditions are held constant, essentially the same products or mixtures of products. An appropriate arrangement of the reagents, their compositions in each individual step, temperature conditions and water addition will be further improved by an addition of hydrogen sulphide, so that a greater range of variation can be achieved with regard to products, and a more precise degree of hydrogenation ( this includes dehydrogenation of one or more product streams when this is desired).

With suitable alkali metal sulphides, mixtures of sulphides and mixtures of the aforementioned sulphide hydrates with hydrogen sulphide, it provides the desired reagent stability, and the selected product. Thus, when the reagent is kept in an active state by the addition of hydrogen sulphide, you will achieve that the amount of reagent is reduced, you get a better yield and you get better product control.

The reasons for the addition of hydrogen sulphide can be seen from the subsequent reactions.

When sulfur from the coal is present, the following reaction will occur:

which ig.ij.en leads to the decomposition of & 2S2 is f01(?end:

Thus, if H2S is present, KOH will be converted into KHS, and if some KOH forms the thiosulphate, this will be converted into K2S5«

Other reactions are the following:

(x can e.g. be 2.5, etc, depending on the temperature).

Consequently, sufficient H2S must be present for the reactions to take place under such conditions that the reagent is stable, i.e. that the sulfur is taken up either when it is secreted from the coal or from the reagent, and that hydrogen sulphide means that the reagent is not hydrolysed. The thiosulphate which is possibly developed by the oxygen from the coal is regenerated during the reaction to the desired ^ 25s sulphate« The reagent is thus kept at the desired hydrolysis level of H2S.

Of the various reagents, the following are preferred because of their stability and availability of sulfur, KHS, NaHS, K2S, K2S2, K2S3, and of these one has the following preferred order: K2S2, K2S and then K2S3. The other sulphides are unstable due to their melting points, e.g. melts Na2S2 at 445°C, Na2S4 at 275°C, or emits sulfur at 760 mm, e.g. gives K_S._ at 300°C KS. +S,

Z 3— 4 K2S4 at 460 C gives K2S3+ S, and K2S3 gives K2S2 + S at 780 C.

The melting points for the alkali sulphides given above are the following: for K2S at 948°C, K9S2 at 470°<S, K2S3 at 279°C (solidification point); K2S4at 145 C,

K2S5 at 206°C, and K2Sg at 190°C. The melting point for mixtures of the sulphides (pure or eutectic mixtures) is as follows: for K2S - K2S2 it is 350°C, for K2S2 - K2S3 it is 225°C, for K2S3, for K2S3 - K2S4 it is approx. 11© °C and for K2S4- K2S5 it is 183°C. Based on the parameters mentioned above, suitable temperature conditions will be chosen depending on decomposition and/or melting points so that a solid reagent or a stable liquid reagent can be used to coat the coal. Of course, the different hydrates of the alkali sulphides will have different melting and/or decomposition points, which is of course also the case for the eutectic mixtures. These temperature points can easily be determined thermographically, which is well known in the industry.

The coal conversion process takes place without the reagent becoming unstable, i.e. the alkali sulphide hydrate becomes unstable, which is due to the fact that the hydrogenation of coal takes place rather than a reagent decomposition, and that an addition of the hydrogen sulphide supports the stabilization of the reagent. While the reaction of coal takes place with suitable amounts of reagent, the addition of hydrogen sulphide will also reduce the amount of reagent required, because the reagent is then in a more stable form, whereby the method is also improved here. The use of hydrogen sulphide at least doubles the product recovery when all other conditions are the same.

Usually, the hydrogen sulphide addition will be on a space time rate basis and will typically be in the range from approx. 10 ml/min/litre to 30 ml per my. per liters in relation to the reactor space, and approx. 20 ml/min./litre is typical. Put another way, approx. half a grammole and less H2S be added for every 1000 ml of water removed by the hydrogenation reaction. In describing various sulfides and their decomposition temperatures and other reactions in this regard, reference is made to U.S. Pat. patent 4,210,526 issued July 1, 1980.

At the highest operating temperature, e.g. 4 50°C,

then K0SC will give sulphur, (which is very advantageous as will be explained below in connection with a dehydrogenation of the process stream). As the decomposition temperature is lowered at lower pressures, it is possible to fully realize a coal conversion at atmospheric pressure, although you lose some advantages that you get by

apply increased pressure, e.g. over approx. 5 atm., and increased costs etc. make this a less desirable method for carrying out the coal conversion method. For practical purposes, the variation of the pressure will be in the range from 1/2 atmosphere to approx. 5 atmospheres, while normal pressures are preferred.

Although the reaction mass of charcoal and reagent can be stirred, it is best to pre-coat the charcoal with reagent in the absence of oxygen, as oxygen tends to destroy the reagent.

For this reason, it has also been found more advantageous to use a liquid or a dissolved reagent. Liquid but stable reagents may be used to coat the coal at or above a suitable melting point for the selected reagent, or for a liquid eutectic mixture of such reagents.

Thus, a mixture of K2S3-K2S4 can be used above 110°C in a liquid state to coat the coal. As a solvent for the above reagent, it has been found very advantageous to use glycerol. Any solvent which will dissolve the sulphides and which will not affect their activity can be used. About. 88 grams of KHS can be dissolved so that you get 200 ml of glycerol solution. When the mixture is heated to 175°C (glycerol will decompose above 190°C)

water will be driven by the dissolved KHS mixture and the mixture will then contain K2S. xH20. Oxygen must also be excluded

from this reaction mixt. Said mixture can then easily be used for coating coal, and thus serve as a reagent.

As the degree of attack on sulphur, nitrogen and oxygen in the coal is a function of the reactant composition and amount of reactants, the following points can be mentioned. Gas conversion of coal is achieved when the strongest breakdown of the coal is obtained due to the reagent. Less vigorous decomposition produces lighter distillates. At 175°C, sulfur will begin to dehydrogenate the coal and the presence of sulfur is thus not desirable for coal conversion. A stable reagent is therefore used under these conditions. In the case of a transformation, i.e. a dehydrogenation and reaction of dehydrogenated compounds with each other, the above-mentioned reaction is important as this makes it possible to obtain liquids with different boiling points, or a preselected API number. Of course, coal-derived gases will be the ideal starting point for the conversion of hydrocarbons. As mentioned above, however, the quality of the coal will also affect the reactions. When it comes to poorer types of coal, the least degradation will be achieved when reagents with a high sulfur content are used. To obtain complete gasification, the amount of sulfur in the reagent should be lowered, e.g. by using K^S, while K_Sr is used for less powerful attacks. This is especially the case for peat when it is reacted with K_Sr, which essentially gives naphthalene.

The following examples illustrate the invention.

Example 1

A reaction vessel with a capacity of approximately 4 liters was equipped with a steam supply line, heating-cooling devices, a thermodome, a stirrer, and an outlet pipe for reaction gases. Hydrogen sulphide was added together with steam, but could also be added separately. The products are recovered in a cooler that was suitably cooled at the same time as the gs gases were collected as described in connection with the figures.

800 grams of Kenucky No. 9 coal with helium gas in the above vessel was added to a liquid mixture of I^S^ and K^S . 5H2O. The added amount of reagent mixture was 2 moles, i.e. one mole of each sulphide. One mole of I^S;} kle obtained from a mixture of I^S and ^S,. in water solution adjusted to an empirical formula of K^S^-A further 4 grams of KOH were added, which means that one drives' of NH^ at the process conditions. The mixture was stirred so that the coal particles were observed and moistened with the reagent.

After this, steam was added together with H2S i

a quantity of 80 ml/min at 50°C. The reaction was exothermic and it was not allowed to rise above 450°C, but the temperature was kept as much as possible between 350 and 390°C. Steam was added at a temperature of 135°C in an amount corresponding to the withdrawal of hydrocarbon or 130% thereof, and the product obtained was a clear yellower solution than when treated under the same conditions with 19 grams of KHS, up to 240° C, gave a complete distillation to a water-clear liquid hydrocarbon distillate (almost water-clear hydrocarbon) and with water-

similar viscosity. A total of 324 ml of distillate was recovered, including 12 liters of (N.T.P.) gas during the first reaction-in-stream. The product was analyzed with the following result:

Eczema 2

To illustrate the effect of the tt^-r addition, 110 grams of bituminous coal (on a dry ashless basis) were reacted with solid NaHS (technical grade), or KHS (in water solution) in a reaction vessel as described earlier, and the addition of H2S was 80 ml/min and 200 ml helium. Steam was added at 137°C in an amount which accounted for 130% of the hydrocarbon condensate outlet. Addition of KOH suppresses ammonia reactions inside the reactor and expels ammonia. The reaction becomes exothermic at 390°C. 252 liters of gas and 70 ml of liquid hydrocarbon condensate were recovered before the reaction becomes exothermic above 390°C.

When experiments were carried out on lignite with and without

H2S addition, yields were more than doubled when H2S addition was used. The other reagents were as indicated in example 1. The reaction was also exothermic above 390 C.

About. 3 mol H2S per mol K^^^ is required. Furthermore, 48 grams of coal-based oxygen were used when one mole of K2S2O3 was formed.

About. 4 2% of the wood is oxygen and approx. 2% anthra-sit. Between these limits, t^S was added based on the above reaction as a maximum as there are other competing reactions.

The above is a rough indication of the amount of H2S that is needed, but in practice smaller amounts will be used due to side reactions between diatomic hydrogen which combines with oxygen to form water.

When KHS and/or NaHS are used, these will give large amounts of gas, and the reaction will be exothermic above 390°C. K2S2 " ^H2° Plus K2S (emPir:i-skf based on equimolar amounts of K2S • 5H20 and K2S3) gives little gas and large amounts of liquid condensate from the same starting material, but the reaction is exothermic from the beginning, i.e. from about 50°C , and the reaction is self-sustaining at 390°C with little heat input K2S2 (derived from a melt of K2S • 5H20 plus sulfur) mixed with small amounts of K2S (prepared from hot aqueous KOH solution plus sulfur in a ratio of

6K0H + 4S) as reagent, gives liquid distillate and gas. The reaction becomes exothermic at 240°C when using the same starting material. In all three cases, the starting material was -200 mesh Kentucky No. 9 bituminous coal and the reaction conditions were otherwise identical as previously described. The aforementioned experiments show the possibilities of obtaining gas, gas and distillates, and possibly only distillates, and show that the exothermic reaction is very advantageous. During these exothermic reactions, completely negligible amounts of CO and CO,, are formed. The hydrogen sulphide was not detectable in the gas streams after washing. No COS was formed either.

The above is further illustrated in the following example.

Example. 3

Of the following reagent on Kentucky No. 9 charcoal:

of each of (1) and (2) above, and half a mole of each was used to prepare the reagent.

The coal analysis was as follows:

Example 3 shows a typical processing of coal and conversion of the same into liquid products.

It has been described above that a number of different hydrocarbons can be easily produced from coal by means of a flexible process which is carried out at low temperature, low pressure and, under certain conditions, also exothermicly.

Claims (27)

Process for converting coal or peat into gaseous hydrocarbons or volatile distillates or mixtures thereof by reacting coal or peat with, as a reagent, a hydrosulfide, a sulfide or a polysulfide of an alkali metal or mixtures of such, characterized by . that the conversion reaction is carried out in the presence of water or hydrogen sulphide and possibly sulfur at temperatures between 50 and up to 450°C in one or more steps where the temperature in each step can be the same or different, and where said reagent can be the same or different based on the sulfur content of the reagent, after which volatile liquid distillates or hydrocarbon gases are recovered. 2. Process for converting coal, peat or wood into gaseous hydrocarbons or volatile distillates or mixtures thereof, by reacting coal, peat or wood, and as a reagent, an alkanol solution of an alkali metal hydrosulphide, a sulphide, a polysulphide, or a mixture thereof, characterized in that the conversion reaction is carried out at temperatures from 50°C or higher, in the presence of water such as water of hydration, pure water or steam, with hydrogen sulphide present and where said reaction is continued. in one or more steps at temperatures up to 450°C, and wherein the temperature is the same or different in each step, and the reagent is the same or different based on the sulfur content of the reagent, and further carrying out said reaction under exothermic conditions in at least a first step, recovering the volatile liquid distillates and hydrocarbon gases. 3. Method according to claim 2, characterized in that elemental sulfur is added to an alkanol solution of said alkali metal hydrosulphide. 4. Process according to claim 2, characterized in that said alkali metal hydrosulfide is potassium hydrosulfide. 5. Method according to claim 2, characterized in that said alkali metal sulfide is sodium hydrosulfide. 6. Method according to claim 2, characterized in that said alkali metal hydrosulphide is a mixture of rubidum, potassium and sodium hydrosulphides and sulphides. 7. Method according to claim 2, characterized in that hydrogen sulphide is recovered. 8. Method according to claim 2, characterized in that said coal is lignite coal. 9. Method according to claim 2, characterized in that said coal is sub-lignite. 10. Method according to claim 2, characterized in that said coal is anthracite coal, partially oxidized anthracite coal, bituminous or sub-bituminous coal. 11. Method according to claim 2, characterized in that peat is reacted. 12. Method according to claim 2, characterized in that said alkali metal is potassium. 13. Method according to claim 2, characterized in that part of the distillate is treated in another step with a reagent with a higher sulfur content in the presence of hydrogen sulphide. 14. Method according to claim 2, characterized in that the reaction is carried out at temperatures between 13 5 and 4 50°C. 15. Method according to claim 14, characterized in that the reaction is carried out at temperatures between 170 and 380°C. 16. Continuous method for converting coal, peat or wood into gaseous hydrocarbons and volatile distillates, characterized in that the coal, peat or wood is fed continuously into a reaction zone, coated with a reagent and where said zone is kept at between 50 and 450° C, and where said coal, peat or wood is treated in such a way as to expel atmospheric oxygen, and where a hydrosulfide, a sulfide or a polysulfide of an alkali metal or mixed alkali metals or mixtures of the hydrosulfide, sulfides and polysulfides of said metals are used as a reagent for coating the said coal, turf or wood; introducing hydrogen sulphide, water or steam into at least one reaction zone at temperatures between 160 and 450°C; reacts continuously in at least one zone at a predetermined temperature and at a predetermined reagent composition, said coal, peat or wood or their decomposition products with 1) a predetermined reagent based on the sulfur content of said reagent, its hydrate form, or its melting points or the same, or 2) mixtures of said reagents in the presence of said supplied water, steam or hydrogen sulphide; it recovers volatile and/or gaseous products from said reaction zone; recovering hydrogen sulfide from said reaction zone; recovers coal, peat or wood ash from said reaction zone; recovers unreacted reagent in said coal, peat or wood ash and the alkali metal content as alkali metal hydroxides; reacting said alkali metal hydroxides with at least a portion of the hydrogen sulfide given off during said reaction, and reconstituting said reagent and recovering hydrogen sulfide for supplying it to the reaction; introduces a sufficient amount of said reconstituted reagent into said reaction zone, so that said reaction between the coal, peat or wood or their decomposition products and said reagent continues. 17. Method according to claim 16, characterized in that the first reaction zone is kept at a fixed predetermined temperature for the production of gaseous hydrocarbons. 18. Method according to claim 16, characterized in that the reaction zone is kept at a temperature which is suitable for recovery of a predetermined liquid hydrocarbon fraction. 19. Method according to claim 17, characterized in that gaseous hydrocarbon is treated in another reaction zone with another reagent to produce liquid distillates. 20. Method according to claim 17, characterized in that lignite coal is the coal that is reacted. 21. Method according to claim 17, characterized in that potassium sulfide, potassium polysulfide, a potassium hydrosulfide or hydrates thereof, or a mixture thereof is used as a reagent. 22. Method according to claim 17, characterized in that said reaction is exothermic in a first reaction zone. 23. Method according to claim 17, characterized in that the temperature in said reaction zone is between 170° and 450°C. 24. Method according to claim 17, characterized in that said hydrocarbon product, whether in liquid or gaseous form, is treated in separate steps with said alkali reagent with increasing sulfur content in discrete increasing temperature ranges below 400°C, but above 100°C. 25. Method according to claim 24, characterized in that the gaseous hydrocarbons are washed with an alkali metal hydroxide solution, whereby hydrogen sulphide is removed from said gaseous hydrocarbons as a reaction product with said alkali metal, and then said reagent is recovered for recycling thereof. 26. Method according to claim 17, characterized in that a theoretical composition of & 2S3 p^ basis of material balance is used as said reagent. 27. Method according to claim 17, characterized in that anthracite coal or oxidized anthracite coal is reacted with said reagent.