DE1107666B - Process for the partial oxidative degradation of lignite - Google Patents

Description

Process for the partial oxidative degradation of lignite The invention relates to a new and improved process for partial oxidative degradation of lignite and the extraction of the oxidation products made from it. lignite is generally a brown charcoal in which the original wood structure is still present can be seen and which still contains 25 to 450/0 water. Geoceric acid could be extracted from the lignite (C28Hs "O2) as well as montan wax can be obtained.

Lignite consists essentially of cyclic hydrocarbons and is used for the most part as fuel after looking at the water content of the lignite has dried to about 50/0 of its original water content. Consequently the drying of the lignite has hitherto been considered expedient, especially the lignite disintegrates into a fine and light powder in the air.

There has now been a new and improved method for oxidative Treatment of the lignite found after the lignite with its natural moisture content is oxidized, whereby one besides defined low molecular weight oxidation products can also win higher molecular weight degradation products that can be used as fuels.

The new process for the partial degradation of lignite with oxidizing acting degrading agents is characterized in that one is its natural Lignite with a water content is oxidized at temperatures between 50 and 3600 C. and the degradation products are separated from one another by extraction in a known manner.

According to the invention, halogens are used as decomposing agents with an oxidizing effect or a nitric oxide applied.

When carrying out the oxidative degradation of lignite using Elevated temperatures can either be done directly by introducing hotter heating Combustion gases in the reaction mixture or indirectly, through the application of the appropriate Heating processes are carried out.

The temperature at which the lignite is treated with the oxidant can be changed within wide limits and from below 0 up to 360 ° C. Using different temperatures results in different Results achieved.

The method according to the invention can be used at different pressures are executed. In general, good results can be achieved within a pressure range Achieve, which ranges from a significant negative pressure to about 8.75 kg / cm2.

Although halogens and nitrogen oxides are used as oxy- dation agent preferred good results can also be obtained using other oxidizing agents achieve, such as nitric acid, free oxygen, sulfur dioxide, sulfur trioxide, Hydrogen peroxide, sodium peroxide, manganese dioxide and potassium permanganate.

The practical implementation of the method according to the invention has shown that the presence of moisture is the oxidation process and thus the Promotes degradation of the lignite. In general it can be stated that lignite with a Water content of about 30 to 40 per cent and above that a better chemical reactivity than is the case with firmer coals. The water content of the lignite leads to a dissolution of the oxidizing agent in the lignite as well as an enlargement the inner surface of the lignite, if, with progressive oxidation, the water for the most part is removed from the lignite. By the well-known drying of the lignite At high temperatures, on the other hand, the surface of the liguit particles is melted smoothly, and surfaces that have been modified in this way require an extension of the implementation time and a less developed chemical change in the molecular structure of the lignite, since the oxidizing agents cannot easily penetrate into the interior of the particles.

The lignite can be mixed with water to remove certain foreign components, z. B. inorganic compounds of calcium, sodium and sulfur washed will. The reaction mixture becomes acidic due to the action of the oxidizing agent, and there is, among other things, such a change in the sulfur content of the Lignite that some of the sulfur present by washing with water after Oxidation process can be removed.

Here, the sulfur is usually obtained in the form of calcium sulfate. It is thus possible according to the invention to remove impurities that are expediently removed separates before the main oxidative degradation takes place. By washing one like that pretreated lignite with water succeeds at this point in the process stage to significantly reduce the lignite constituents that lead to ash and in almost completely removed in many cases.

After washing with water or immediately after acidification and or or the oxidation of the lignite, it is sometimes useful to use a Range of solvents, e.g. B. water, methanol, benzene, acetone, furfural and resp. or to treat carbon tetrachloride to produce products soluble in the solvents to extract and separate. Depending on the character of the applied Solvents or extraction agents can thus be used to make hydrophilic or hydrophobic products separate, the composition of which is also a function of the previously used oxidizing agent, whose amount and temperature is.

After the extractable fractions have been separated off, the remaining lignite can be removed by using oxygen, nitrogen oxides, chlorine, bromine and other oxidizing agents of the type described above are further oxidized, the more so the further, even more complete bring about chemical changes and transformations of the lignite. In general it is usually appropriate to the oxidation and the separation of low molecular weight Carry out oxidation products from the lignite in several stages. The practical one Practice of the invention has shown that more than 90% of that is present in the lignite Hydrocarbons are converted to obtain technically useful products can.

The process according to the invention can be used to produce carboxylic acids win, which can be used as such, or esterified with alcohols to form esters will. These carboxylic acids are naturally accessible to further reactions, so that further oxygen-containing organic compounds can be obtained. Further useful products that are used in the further oxidation of the partially oxidized lignite are generated are compounds such as hydroxyl, carbonyl, aldehyde or more Contain carboxyl groups and their halogenation products, nitric acid esters and unsaturated tar asphalt compounds. These products can be selective through Hydrogenation can be converted into other useful products.

One of the main uses for the partial ligature degradation products is the production of lignite solutions in petroleum fractions. Such new connections can be made viscous and pliable or friable and brittle. Through the Mediation of such different physical Properties can be the corresponding Lignite degradation products receive special properties that are necessary for their further application are appropriate.

The procedure according to the invention thus results in a large number gained in valuable products that are used as starting compounds in the chemical industry Can find application. This applies in particular to the water-soluble carboxylic acids to. The previously known procedures for the oxidation of fuels preferably work with an oxygen-containing gas, but are rarely used water-soluble carboxylic acids obtained. The oxidative one continues to be found in the literature Degradation of fuels with the use of nitric acid possibly in one Autoclave has been described. However, in this case, too, are not worth mentioning Amount of water-soluble carboxylic acids obtained, but not defined products which only dissolve in organic solvents.

The invention will be described below with reference to the drawings explained in detail.

Fig. 1 is a flow diagram of the process of the invention for partial Oxidation of lignite; Fig. 2 and 3 give embodiments of the device for Oxidation of the lignite again; FIG. 4 is a part of the device according to FIG. 2.

In the procedure according to the invention, the lignite is preferred partially oxidized and the reaction products obtained from the oxidized lignite.

The preferred procedure is illustrated in FIG. In the Device 1 is lignite in the presence of water, which is optionally acidified is ground to form a slurry.

The lignite is crushed to a grain size of one clear mesh size of 0.84 mm.

The resulting mixture is then partially oxidized by it in a first reaction vessel 2 in contact with a gaseous oxidizing agent, e.g. nitrogen oxides and / or a halogen, e.g. B. chlorine or bromine, in contact brings. Such oxidizing agents are supplied from a storage container or device 3. In a second reaction vessel 4, the implementation takes place End led. Vapors produced during the oxidation from the second reaction vessel 4 are at least partially returned to the first reaction vessel 2, or the same are in a distillation column 5 from the lower-boiling fractions stripped and collected as condensate. The condensate can be in different fractions Boiling points are separated.

The insoluble residue from the oxidative degradation can alone or in a mixture with crude kerosene, coal tar products, coke oven tars and / or natural oils be used as fuel. The residue from the second reaction vessel 4 can also filtered in the device 6, resuspended and again with nitrogen oxides and then treated with crude kerosene, coal tar products, coke oven tars and / or or natural oils can be mixed. Petroleum, coal tar products, coke oven tar and / or the natural oils can also partially z. B. by treatment with Nitric acid, nitrogen oxides or a halogen are treated and then with the partially oxidized lignite are mixed.

In the initial stages of the process it is useful to use the lignite with an oxidizing acid, e.g.

Nitric acid, in order to accelerate the oxidation of lignite.

The oxidation products also contain polycarboxylic acids, which by Crystallization or solvent extraction of the condensates and / or the residues, obtained from lignite oxidation can be obtained. The products of the Oxidative degradation of ligaments can be used as fuel oils. The same can but also further through solvent extraction processes, cracking, hydrogenation, dehydrogenation, Hydroforming processes and through the use of others in the petroleum industry known processes are processed.

The invention is illustrated by the following examples in which the amounts are by weight, unless otherwise stated.

Example 1 An apparatus according to FIG. 2 was used.

The reaction chamber 1 was made with 589 parts of lignite from the grain loaded with a clear mesh size of 0.84 mm. The burner 2 (see also Fig. 4) was used to generate the required heat of reaction with natural gas and oxygen operated. Nitric dioxide (NO) was added dropwise to vessel 3 with nitric acid produced from the container 4 onto the copper located in the vessel 3. Air became introduced from the T-shaped pipe 6. Compressed air can also flow through the pipe 5 be brought into the vessel 3 to the nitrogen dioxide through the line 6 and to lead the outer casing of the burner 2, where the nitrogen dioxide is heated and with is mixed with the combustion gases. The resulting hot gas mixture, which in the consists essentially of nitrogen dioxide, nitrogen, oxygen and carbon dioxide, was passed through the tube 7 into the lignite layer of the vessel 1. The temperature the gas mixture and the lignite were observed by the thermometers 9 and 10. The gases in the reaction chamber 2 had a temperature of about 1200 C. Die Gases above the lignite in the reaction chamber 1 had a temperature of approximately 600 C.

The gases were blown through the lignite layer for 4 hours. After this time the oxidation product was somewhat darker than the original dark brown one used lignite. 10 parts of this oxidation product were distilled with Washed water and filtered. The filtrate was acidic and gave on evaporation a considerable amount of a white, solid mixture, consisting mainly of small, consisted of flat, irregularly shaped crystals. It is a hygroscopic and water-soluble cyclic polycarboxylic acid, their physicochemical Data were not determined.

The vapors generated during the reaction were passed through the pipe 11, which has been cooled by the cooler 12, is performed. The condensate collected in the vessel 13. A pipe 14 connects the vessel 13 to a vacuum pump. The vessels 15 and 16 contained a coolant to control the reaction temperature in vessel 13, z. B. water mixed with ice or solid carbon dioxide.

After a test duration of 4 hours, the vessel 13 were given 10 parts of the condensate taken and with part of the filtrate of the reaction product from the vessel 1 united. The filtrate, when incorporated, gave the same crystals as from the filtrate of the reaction product from the reaction vessel 1 had been recovered.

In the present example, the burner 2 had a burner nozzle or mixing plate 17 according to FIG. 4.

The fuel gas (e.g. methane or hydrogen) was passed through a Line 18 controlled by a valve 19 was introduced and passed through an inner tube 20 to the burner nozzle or a mixing plate. The oxygen was released through one of the valve 22 controlled line 21 brought to the concentric outer space at a point 24, which was sealed against the outer space 20, so that the mixing of the oxygen and the combustible gas at the mixing plate or burner nozzle 9 takes place. The mixture from oxygen and fuel gas was ignited, the flame spreads in the combustion chamber 25 off.

After the burner was ignited, it was placed in the reaction chamber 27 inserted and fastened there.

The flame was observed through a sight glass 26. The flame size was regulated so as to increase the heat generation and thereby the reaction temperature steer. Inlet ports 28 and 29 controlled by valves 30 and 31 were used to introduce nitrogen dioxide or other oxidizing gases. Of the Channel 32 controlled by valve 33 was used to introduce further gases, e.g. B.

Air, nitrogen or carbon dioxide as an additional oxidizing agent or as a coolant. The mixture of oxidizing gases was released into the reaction chamber 1 through line 34, the coolant is introduced through line 35. The shaft 36 was used to hold the thermometer9 (cf.

Fig. 2) to determine the temperature of the gas mixture. The outer housing27, likewise the other pipes of the device from the sight glass 26 to the shaft 36 are made of stainless steel.

The other parts of the device are made of iron or brass. the Gas pressures in the present device were adapted to the fragile equipment. In the case of technical systems, the pressures are changed according to the end products, which are to be made from the lignite.

Example 2 The apparatus of Figure 3 was used.

848 parts of lignite of one grain size with a clear mesh size of about 3 mm were in the reaction vessel 37 up to the approximate level according to FIG covered with water so that the water level is above the top of the combustion chamber 39 of the submerged burner 40 was located.

Hydrogen was used as fuel. Oxygen was used for maintenance used for combustion in the burner. Nitrogen dioxide and air were in the burner brought through line 41 and passed down into the annular space 42 between the inner tube 43 for the supply of oxygen and hydrogen and the outer casing 44. The flame was generated inside the combustion chamber 39 and the heat generated by the nitrogen dioxide and the air, which by the Tube 41 were inserted into the annular space 42 between the tubes 43 and 44 forwarded that are not arranged concentrically to one another are.

The nitrogen dioxide, air, and products of combustion mixed when they entered the aqueous lignite suspension at point 45.

Additional water was drawn from a separate funnel 46 for maintenance of the liquid level added above the upper end 38 of the burner housing. The temperature was observed by the thermometer 47. The reaction vapors arrived up through the pipe 48 into the template 49 and from there to the cooling pipe 50, where they were cooled by the cooler 51. The condensate was collected in vessel 52. It was under vacuum via tube 53, as were vessels 49 and 37.

The exact physicochemical values of the products obtained were not determined, since the present procedure essentially depends on to modify the lignite so that valuable compounds and fuels are preserved without the need to carry out a destructive distillation, so does the constitutional water and the chemically bound water from the Remove starting material.

Example 3 The device used was similar to that of FIG Exception that a template as in Fig. 3 between the reaction chamber 1 and the Condensate collecting vessel has been switched. 848 parts of liguit were saturated with water and brought into the reaction chamber 1. The oxygen-hydrogen flame was ignited. The nitrogen dioxide gas was introduced into the moist ligature layer. The temperature was in the reaction chamber 1 for about 11/4 hours to about 100 to 1200 C held. Then the burner was turned off. Nitrogen dioxide and air became continued to pass through the lignite continuously for 11/4 hours. Gray-brown fumes arose and entered into the template. The gas in the reaction chamber 1 had a temperature of 360 C before the oxygen-hydrogen flame was extinguished. Then the temperature dropped to 1800 C.

The liquid in the template was bluish red litmus paper and had a burnt wood smell similar to the creosote smell. The reaction chamber 1 was covered with a black-brown, tar-like condensate.

Example 4 100 parts of lignite of an average particle size of about 3 mm were wetted with water and then in a reaction vessel as described Kind oxidized with chlorine and air. That was wet, originally almost black lignite dried and turned lighter brown as the water was removed and the reaction took place. The reaction vessel was heated until the gases in it were above the lignite layer had a temperature of about 40SC. 83.5 parts of reaction product, pulled on the lignite used, were obtained from the reaction vessel.

Example 5 100 parts of a water-leached lignite from a average particle size of about 3 mm were added to the reaction vessel 37 a device similar to that used in Example 3, brought. Bromine and air were passed through the lignite, the temperature in the lignite from initially 16.80 C rose to 300 C when introducing bromine. The amount of air was increased until the temperature dropped to about 200C. The moist, originally almost black one Lignite became lighter in color until it was roughly brown, creating another beneficial change of the source material is displayed.

Example 6 40 parts of raw, undried lignite of one grain size with a mesh size of 0.84 mm were treated with nitrogen dioxide for 2 hours and air (2o / oNO2 and 989 / o air) at about 290C. The one in the reaction vessel remaining lignite was washed with water and then dried on filter paper. 31 parts of dark brown solids remained after filtering. The filtrate on evaporation to dryness gave about 100% of the use of a pale yellow solid substance, which indicates a beneficial change in the lignite. The water-soluble residue of the oxidized lignite showed due to its appearance that it has undergone a great change.

Example 7 589 parts of raw, undried lignite of one grain size with a mesh size of 0.84mm were filled with nitrogen dioxide approximately at 1130 C according to Example 1 oxidized. The resulting material was brown, different but differ from the original lignite by changing the solution and color properties.

Claims (2)

PATENT CLAIMS: 1. Process for the partial degradation of lignite with oxidizing dismantling agents at elevated temperature in the presence of water characterized in that one has its natural water content Lignite is oxidized at temperatures between 50 and 3600 C and the degradation products in known way separates from each other by extracting. 2. The method according to claim 1, characterized in that the Carries out oxidation with nitrogen oxides or halogens as oxidizing agents. Considered publications: German Patent Specifications No. 743 325, 766 204, 766206, 766205, 862 896, 864992, 892895, 912 331.