CN110846099A - Method for removing organic sulfur in coal based on solar STEP thermal-electrochemical coupling - Google Patents

Abstract

The invention relates to a method for removing organic sulfur in coal based on solar STEP thermal-electrochemical coupling. The method comprises the following steps: (1) pretreating coal to obtain coal powder; (2) placing a solid material formed by mixing the coal powder and the solid electrolyte in a closed electrolysis device; and (3) electrolyzing the solid material at the temperature of 320-380 ℃ and the voltage of 1.8-3.0V, providing the heat energy required by electrolysis through a solar heat collection device, and providing the electric energy required by electrolysis through a photovoltaic cell. The invention provides a method for removing organic sulfur in coal based on solar STEP thermal-electrochemical coupling for the first time, and organic sulfur in coal, especially dibenzothiophene, is driven to be converted into stable sulfate radicals by utilizing solar photo-thermal and solar photo-electric processes so as to achieve the aim of purifying coal. The energy required by the method is completely derived from solar energy, and no additional energy is required to be added in the process.

Description

Method for removing organic sulfur in coal based on solar STEP thermal-electrochemical coupling

Technical Field

The invention relates to the technical field of coal treatment, in particular to a method for removing organic sulfur in coal based on solar STEP thermal-electrochemical coupling.

Background

China is a big coal-fired country, the utilization of coal is mainly combustion, but with the increase of the mining depth of coal, the content of sulfur in the coal is higher and higher, which means that the sulfur dioxide generated in the combustion process of the coal is increased. Sulfur dioxide is an acid gas, is one of the main pollutants of the atmosphere, can form sulfurous acid with water when being discharged into the atmosphere, and the sulfurous acid can be further oxidized in the air to generate sulfuric acid to generate acid rain, which is just a problem worried by people in the utilization process of coal at present. China is still in the middle stage of development, social development and economic development both need energy support, and coal is still the main source of energy in China for a long time in the future, so in order to ensure production, meet industrial requirements, and also protect the environment in which people live, people begin to research and develop green and environment-friendly utilization modes of coal, so that the utilization of coal can meet the requirement of environmental protection.

The electrochemical desulfurization technology is a mild desulfurization method which is carried out at lower temperature and normal pressure, the process is easy to realize, and the equipment required in industry is simple. This technology has been proposed as early as the sixties, and a great deal of research has been conducted on this technology after the seventies. Many scientists in foreign countries have carried out a lot of experiments on H-shaped electrolytic cells with diaphragms, fluidized bed electrolytic cells, electrolysis under alkaline conditions, electrolysis under acidic conditions and the like, but in the research process, the problems that the electrochemical desulfurization technology still has many problems and the investment of the electrolytic cells is too large still troubles researchers. The research of China on electrochemical desulfurization starts late, and in recent years, the research on a diaphragm-free electrolytic cell can remove more than 70% of inorganic sulfur and remove up to 60% of organic sulfur under a mild electrolysis condition, but the main problems of high cost and high energy consumption still cannot be fundamentally solved, and the research on the mechanism of electrochemical desulfurization is not carried out.

Although the organic sulfur content in coal is relatively low, organic sulfur is the most difficult part to remove, and is difficult to remove by simple chemical oxidation. The organic sulfur in coal is mostly present in the macromolecular structure of coal, so it is not present as an independent organic sulfur molecule, but is present as a sulfur-containing functional group in the coal structure. These functional groups typically include thiols, thioethers, dibenzothiophenes. At higher reaction temperatures, thiol groups and thioethers are unstable and decompose during desulfurization. However, dibenzothiophene has a stable structure and can be condensed with organic substances to form polymer sulfides even in the course of high-temperature carbonization.

Solar energy is one of the most safe, greenest and ideal alternative energy sources. The total amount of solar energy resources is huge, the radiation range is wide, the use process is clean, and the problem of resource exhaustion does not exist.

At present, no report of removing organic sulfur in coal by using solar energy is found.

Disclosure of Invention

The invention aims to provide a method for removing organic sulfur in coal based on solar STEP thermal-electrochemical coupling.

In order to achieve the purpose, the invention provides the following technical scheme:

a method for removing organic sulfur in coal based on solar STEP thermal-electrochemical coupling comprises the following STEPs:

(1) pretreating coal to obtain coal powder;

(2) placing a solid material formed by mixing the coal powder and the solid electrolyte in a closed electrolysis device; and

(3) the solid material is electrolyzed at the temperature of 320-380 ℃ and the pressure of 1.8-3.0V, the heat energy required by the electrolysis is provided by a solar heat collecting device, and the electric energy required by the electrolysis is provided by a photovoltaic cell.

Preferably, the electrolysis is carried out at 320 ℃ and 2.0V.

Preferably, the solid electrolyte is powdered sodium hydroxide.

Preferably, the mass ratio of the pulverized coal to the solid electrolyte is 1: (10-15), preferably 1: 10.

Preferably, the electrolysis employs a two-electrode system, the electrodes all being nickel electrodes.

Preferably, the solar heat collecting device is a focusing solar heat collector; and

the solar photoelectric conversion device is a polycrystalline silicon photovoltaic cell.

Preferably, during the electrolysis, the voltage output by the solar photoelectric conversion device is regulated by a voltage stabilizer.

The thermal energy provided by the solar thermal collector is preferably regulated by a temperature control instrument equipped with a thermocouple.

Preferably, the pre-treatment comprises:

(a) crushing coal;

(b) screening the crushed coal;

(c) drying the screened coal; and

(d) and (4) performing deliming treatment on the dried coal.

Preferably, the coal below 120 meshes is screened out by screening;

drying the screened coal at 40-60 ℃ for 20-24 hours; and/or

The deashing treatment is carried out according to the following method: soaking the dried coal with absolute ethyl alcohol, adding 40% hydrofluoric acid solution, and placing the mixed material in a water bath device at 50-60 deg.C while heating and stirring; filtering the obtained material, cooling, adding 50% hydrochloric acid solution, stirring, filtering, washing and drying in sequence.

Advantageous effects

The technical scheme of the invention has the following advantages:

the invention provides a method for removing organic sulfur in coal based on solar STEP thermal-electrochemical coupling for the first time, and organic sulfur in coal, especially dibenzothiophene, is driven to be converted into stable sulfate radicals by utilizing solar photo-thermal and solar photo-electric processes so as to achieve the aim of purifying coal.

The energy (including heat energy and electric energy) required by the method provided by the invention is completely derived from solar energy, the heat energy required by the method is provided by a solar heat collecting device, the electric energy required by the method is provided by a solar photoelectric conversion device, and no additional energy is required to be added in the process.

The invention provides necessary heat energy for removing organic sulfur in coal by utilizing the photo-thermal effect of a long wavelength region, and provides necessary electric energy for removing organic sulfur in coal by utilizing a visible light region, thereby obviously improving the utilization rate of sunlight and realizing full-wave-band utilization of the sunlight.

The method provided by the invention has no problem of secondary pollution.

Drawings

FIG. 1 is a schematic diagram of desulfurization of dibenzothiophene by conventional electrochemical methods;

FIG. 2 is a schematic diagram of the desulfurization of dibenzothiophenes by the process of the present invention;

FIG. 3 is the desulfurization rates at different temperatures; temperature on the abscissa means Temperature (. degree. C.), and desulfurization rate on the ordinate means percent (%) of sulfur removal;

FIG. 4 is a graph showing the change in desulfurization rate under various electrolysis potential conditions; the abscissa Potential means the electrolytic Potential (V) and the ordinate desulfurization rate means the desulfurization (%);

FIG. 5 is a graph showing the relationship between the yield of clean coal and the desulfurization rate under different electrolysis potential conditions.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

The invention provides a method for removing organic sulfur in coal based on solar STEP thermal-electrochemical coupling for the first time. The method simultaneously utilizes the solar photo-thermal and solar photo-electric processes to drive organic sulfur components in the coal to be converted into stable sulfate radicals so as to achieve the aim of purifying the coal; the energy (including heat energy and electric energy) required by desulfurization in the method is completely derived from solar energy, the heat energy required by the method is provided by a solar heat collection device, the electric energy required by the method is provided by a solar photoelectric conversion device, and no extra energy is required to be added in the process; the invention provides necessary heat energy for removing organic sulfur in coal by utilizing the photo-thermal effect of a long wavelength region, and provides necessary electric energy for removing organic sulfur in coal by utilizing a visible light region, thereby obviously improving the utilization rate of sunlight and realizing full-wave-band utilization of the sunlight; the method has no secondary pollution problem. Specifically, the method provided by the invention comprises the following steps:

(1) pretreating coal to obtain coal powder;

(2) placing a solid material formed by mixing the coal powder and the solid electrolyte in a closed electrolysis device; and

(3) the solid material is electrolyzed at the temperature of 320-380 ℃ and the pressure of 1.8-3.0V, the heat energy required by the electrolysis is provided by a solar heat collecting device, and the electric energy required by the electrolysis is provided by a photovoltaic cell.

Conventional electrochemical desulfurization processes are typically carried out at low temperatures below 100 ℃. The inventors found in their studies that the organic sulfur removing effect at low temperature was not significant. The desulfurization method provided by the invention is carried out at the temperature of 320-380 ℃, the temperature region fully utilizes the photothermal effect of solar energy, and the thermal effect is most obvious. In addition, the energy required by the method provided by the invention is all from solar energy, so that the method has no concern of high energy consumption. Considering the instability and uncertainty of the coal quality change and the high temperature reaction, the present invention determines the temperature condition as 320-.

The invention improves the removal effect of organic sulfur by the action of the intensified electric field on the basis of the action of the thermal field. The inventor finds in research that inorganic sulfur and organic sulfur need different electrolytic potentials when undergoing electrochemical reaction, and the electrolytic potential for electrochemical oxidation of organic sulfur is higher than that of inorganic sulfur. At lower potentials, mainly inorganic sulfur is removed, the removal rate of inorganic sulfur increases faster than organic sulfur, while at higher potentials, the opposite rule is followed, the removal rate of organic sulfur increases faster than inorganic sulfur. However, the higher electrolytic potential can cause the oxidation rate of the electrode to be increased, the electrode efficiency can be gradually reduced when the reaction is carried out for a longer time, thereby influencing the desulfurization rate of coal, and the oxidation reaction is too active at an excessively high temperature to be difficult to control, thereby being difficult to avoid the influence on the coal quality. Based on the above, the present invention determines the electrolysis voltage condition to be 1.8 to 3.0V, for example, 1.8V, 2.0V, 3.0V, without continuing to raise the electrolysis potential.

The following is the desulfurization mechanism of the process provided by the present invention:

dibenzothiophene is the most difficult organic sulfur to oxidize during the organic sulfur removal process, so the present invention discusses the mechanism of organic sulfur removal by using dibenzothiophene as a model compound.

As shown in fig. 1, the desulfurization process of dibenzothiophene using the conventional electrochemical method can be divided into five steps. The first step is that dibenzothiophene is primarily oxidized to increase one sulfur-oxygen double bond on sulfur, and two sulfur-oxygen double bonds are increased on sulfur along with the continuous oxidation, and the addition of the sulfur-oxygen bond reduces the bond energy of the original carbon-sulfur bond, so that the carbon-sulfur bond in the generated oxidation product becomes more unstable and is easy to break to generate phenylphenol sulfinic acid. The phenylphenol sulfinic acid is oxidized to generate sulfur dioxide and biphenyl.

It can be seen that dibenzothiophene is not sufficiently oxidized to form sulfur dioxide using conventional electrochemical methods. The release of sulphur dioxide gas is very harmful to the environment and to the reaction equipment, and conventional methods are not very desirable, if at all possible.

The inventors believe that the most important process in the oxidation of dibenzothiophenes is the primary oxidation of sulfur on the basis of the original thiophene structure, which breaks the original thiophene stable structure and makes it more susceptible to the cleavage of the C — S bond by oxidation. In the conventional electrochemical process at a lower temperature, the oxidation process is difficult to be completed at a lower voltage, and considering that the electrolyte is water, if an excessively high voltage is used in the electrochemical oxidation process, the water undergoes a rapid electrolytic reaction, which affects the effect of electrolytic oxidation.

The process of the invention is carried out at elevated temperature. In high temperature environment, the molecule of dibenzothiophene is heated and activated because the heat effect has taken place, makes dibenzothiophene be in the state of an excitation, and the molecule of excited state is more active has higher reactivity under this state, so originally need provide higher voltage just can be with the process of its oxidation, uses lower voltage alright realize under the supplementary of high temperature. Because more active factors can be formed on the surface of the anode in a high-temperature environment, and the molecular motion and the reaction rate are enhanced, the dibenzothiophene can be fully oxidized, so that the final oxidation product is not sulfur dioxide and biphenyl but sulfate and biphenyl.

FIG. 2 is a schematic diagram of desulfurization in the process of the present invention. As shown in figure 2, after two sulfur-oxygen bonds are added to dibenzothiophene, due to enough active factors in the system, sufficient oxidation can be achieved for dibenzothiophene, sulfite is generated instead of sulfur dioxide after generated phenylphenol sulfinic acid is broken, and sulfate is generated through further oxidation of sulfite. By verification, sulfur dioxide is not detected in the product of the invention, so that sulfur-containing organic matters with dibenzothiophene and similar structures can be judged to be fully oxidized in the oxidation process to generate sulfate radicals instead of sulfur dioxide.

In some preferred embodiments, the present invention provides a desulfurization method, which performs the electrolysis at 320 ℃ and 2.0V, so that a better desulfurization effect can be obtained while ensuring a higher yield of clean coal.

In the conventional coal desulfurization, sulfur in coal is removed to obtain purified clean coal, and the final purpose of the method is to reduce pollution of sulfur dioxide in the subsequent use process of the purified clean coal. The method for removing iron and sulfur sulfide based on solar STEP thermo-electric coupling provided by the invention has a remarkable effect on removing organic sulfur in coal, but the inventor also finds that the method has a large influence on coal quality and causes the yield of final clean coal to be reduced. The yield of clean coal showed a tendency to decrease with increasing electrolysis potential and increasing temperature. This is because the increase of the electrolytic potential causes more macromolecular coal to participate in the electrochemical reaction process, which results in the destruction of the macromolecular structure of the coal and the conversion of the macromolecular structure into other forms of substances, and thus the yield of the finally obtained clean coal is reduced. In view of the low organic sulfur content in coal, the electrolysis is preferably carried out at 320 ℃ and 2.0V in the present invention in order to achieve a good desulfurization rate and clean coal yield.

In some preferred embodiments, the solid electrolyte is powdered sodium hydroxide. Sodium hydroxide melts at 318 c and provides better conductivity.

In some preferred embodiments, the mass ratio of the pulverized coal to the solid electrolyte is 1: (10-15) may be, for example, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, most preferably 1: 10.

In some preferred embodiments, the electrolysis employs a two-electrode system, with both electrodes being nickel electrodes. In the electrochemical reaction process, the electrode is used as an important medium for generating the electrochemical reaction, the efficiency of the reaction process, the selectivity of products and the like are influenced and determined, and the selection of electrode materials is very important. In the process of converting the solar STEP coal, the reaction occurs in a high-temperature and high-corrosion environment for a long time, so that the selected electrode needs to be resistant to high temperature and corrosion within a long reaction time, have good physical and chemical stability in a high-temperature environment, and consider factors such as economic cost and industrial realization possibility. The nickel electrode has the advantages of smooth change of electrode potential along with current density, small degree of metal passivation, good electrochemical stability and certain rigidity and strength, so that the nickel electrode is adopted in the invention.

In some preferred embodiments, the solar heat collection device is a focused solar heat collector. In some preferred embodiments, the solar photovoltaic conversion device is a polycrystalline silicon photovoltaic cell. More preferably, during the electrolysis, the voltage output by the solar photoelectric conversion device is regulated by a voltage stabilizer; and/or the thermal energy provided by the solar thermal collection device is regulated by a temperature control instrument equipped with a thermocouple.

In some preferred embodiments, the pre-treatment comprises: (a) crushing coal; (b) screening the crushed coal; (c) drying the screened coal; and (d) subjecting the dried coal to deliming treatment. The coal powder has the appropriate maximum granularity, ash content, uniformity and the like through the pretreatment.

In the pretreatment provided by the present invention, coal is first pulverized to reduce the particle size of the coal and to increase the degree of divergence of the heterogeneous material to make its properties uniform. The crushing can be carried out by a sealed vibration crusher, and the coal is crushed for 1 hour, so that the coal sample is fully crushed. Then, the crushed coal is screened, the coal sample which is not sufficiently crushed and meets the requirement of granularity is screened out, and a sample with the granularity of less than 120 meshes is screened out by a screen. The screened coal sample is placed in a drying oven and dried at 40-60 deg.C (for example, 40 deg.C, 45 deg.C, 50 deg.C, 55 deg.C, 60 deg.C) for 20-24 hours (for example, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours) to remove a large amount of water from the coal sample. And cooling the dried coal sample, and then performing coal sample deashing treatment. Because the collected coal sample contains a large amount of ash, the ash in the raw coal needs to be pretreated to remove a large amount of ash so as to prevent the ash from influencing the desulfurization conversion process of the coal in the experimental process. The deliming treatment can be carried out as follows: soaking dried coal in anhydrous ethanol, adding 40% hydrofluoric acid solution, and heating while stirring the mixture in a water bath device at 50-60 deg.C (such as 50 deg.C, 51 deg.C, 52 deg.C, 53 deg.C, 54 deg.C, 55 deg.C, 56 deg.C, 57 deg.C, 58 deg.C, 59 deg.C, 60 deg.C); filtering the obtained material, cooling, adding 50% hydrochloric acid solution, stirring, filtering, washing and drying in sequence.

More fully, the method provided by the invention comprises the following steps:

(1) pretreating coal to obtain coal powder;

the pretreatment comprises the following steps: (a) crushing coal; (b) screening the crushed coal, and screening the coal with a particle size of less than 120 meshes; (c) drying the screened coal at 40-60 ℃ for 20-24 hours; and (d) subjecting the dried coal to deliming treatment. The deashing treatment is carried out according to the following method: soaking the dried coal with absolute ethyl alcohol, adding 40% hydrofluoric acid solution, and placing the mixed material in a water bath device at 50-60 deg.C while heating and stirring; filtering and cooling the obtained material, adding 50% hydrochloric acid solution, and sequentially stirring, filtering, washing and drying;

(2) putting a solid material formed by mixing coal powder and a solid electrolyte into a closed electrolysis device; the solid electrolyte is powdery sodium hydroxide; the mass ratio of the pulverized coal to the solid electrolyte is 1: (10-15), preferably 1: 10;

(3) electrolyzing the solid material in the step (2) at the temperature of 320-380 ℃ and the voltage of 1.8-3.0V, providing temperature conditions required by electrolysis through a solar heat collection device, and providing voltage conditions required by electrolysis through a solar photoelectric conversion device; preferably, the electrolysis is carried out at 320 ℃ and 2.0V; a double-electrode system is adopted for electrolysis, and electrodes are nickel electrodes; the solar heat collecting device is a focusing solar heat collector; the solar photoelectric conversion device is a polycrystalline silicon photovoltaic cell; during the electrolysis, the voltage output by the solar photoelectric conversion device is regulated by the voltage stabilizer; the thermal energy provided by the solar thermal collection device is regulated by a temperature controller equipped with a thermocouple.

The following are examples of the present invention.

Example 1

The coal sample used is typical high-sulfur coal in China, and is mined in the coal field of Hongyang Liaoyang in Liaoning province. Crushing raw coal, and crushing a coal sample for 1 hour by using a sealed vibration crusher to fully crush the coal sample. Then, the coal sample is screened, the coal sample which is not sufficiently crushed and does not meet the requirement of granularity is screened out, and a sample with the granularity of less than 120 meshes is screened out by a screen. And (4) placing the screened coal sample in a drying box to be dried for 24 hours so as to remove a large amount of moisture in the coal sample. And cooling the dried coal sample, and then performing coal sample deashing treatment. The deliming treatment is carried out according to the following method: soaking the dried coal with anhydrous ethanol, adding 40% hydrofluoric acid solution, and heating while stirring in a 60 deg.C water bath. Filtering and cooling the sample, adding excessive 50% hydrochloric acid solution, stirring, filtering, washing for multiple times, cooling and drying for later use.

The prepared coal samples were subjected to property analysis according to national standards GB/T212-2008 and GB/T476-2008, and the analysis results are shown in Table 1.

TABLE 1

Water content/%)	Ash content%	C/％	H/％	O/％	N/％	S/％
							17.5	21.8	75.28	3.89	10.28	1.76	6.23

The total sulfur and various forms of sulfur in the prepared coal samples were analyzed according to the national standards GB/T214-2007 and GB215-2003, and the analysis results are shown in Table 2.

TABLE 2

Total sulfur (S)t,d％)	Sulfate sulfur (S)s,d％)	Iron sulfide sulfur (S)p,d％)	Organic sulfur (S)o,d％)
				6.23	0.28	4.21	1.74

The method for desulfurizing the coal after the treatment comprises the following steps:

mixing coal powder and sodium hydroxide powder, wherein the mass ratio of the coal powder to the sodium hydroxide is 1: 10. And putting the mixed solid material into a closed electrolysis device, and electrolyzing the solid material for 4 hours at 320 ℃ and 2.0V by adopting a double-electrode system, wherein the electrodes are all nickel electrodes. Providing a temperature condition required by electrolysis through a focusing solar heat collector, and providing a voltage condition required by electrolysis through a polycrystalline silicon photovoltaic cell; during the electrolysis, the voltage output by the polycrystalline silicon photovoltaic cell is regulated by a voltage stabilizer; the thermal energy provided by the focusing solar collector is regulated by a temperature controller provided with a K-type thermocouple.

Example 2 to example 4

Examples 2 to 4 are substantially the same as the method of example 1, except that: the electrolysis temperature conditions in examples 2 to 4 were 340 ℃, 360 ℃ and 380 ℃, respectively.

As can be seen from fig. 3, the removal rate of organic sulfur continues to increase with the increase of temperature, and the increasing speed is improved more, and the removal rate of inorganic sulfur hardly changes, which indicates that inorganic sulfur has reached the bottleneck of removal, and there is no room for further increasing, and the total desulfurization rate keeps a certain rising trend with the increase of the removal rate of organic sulfur.

Note that, in the present invention, the total desulfurization rate is (amount of organic sulfur removed + amount of inorganic sulfur removed)/total sulfur amount × 100%; the removal rate of organic sulfur is the amount of removed organic sulfur/total amount of organic sulfur multiplied by 100%; the removal rate of inorganic sulfur is the amount of inorganic sulfur removed/total amount of inorganic sulfur × 100%.

Example 5 to example 14

Examples 5 to 14 are substantially the same as example 1 except that: the electrolytic potential conditions of examples 5 to 14 were 1.0V, 1.2V, 1.4V, 1.6V, 1.8V, 2.2V, 2.4V, 2.6V, 2.8V, and 3.0V, respectively.

As is apparent from fig. 4, at lower potentials, mainly inorganic sulfur is removed, the removal rate of inorganic sulfur increases faster than organic sulfur, and at higher potentials, the opposite phenomenon occurs.

FIG. 5 is a graph showing the relationship between the yield of clean coal and the desulfurization rate under different electrolysis potential conditions. As can be seen from fig. 5, the desulfurization rate showed an increasing tendency with an increase in the electrolysis potential, while the yield of the clean coal showed a decreasing tendency. This is because the increase of the electrolytic potential causes more macromolecular coal to participate in the electrochemical reaction process, which results in the destruction of the macromolecular structure of the coal and the conversion of the macromolecular structure into other forms of substances, and thus the yield of the finally obtained clean coal is reduced. In the conventional coal desulfurization, sulfur in coal is removed to obtain purified clean coal, and the final purpose of the method is to reduce pollution of sulfur dioxide in the subsequent use process of the purified clean coal. The method provided by the invention has a certain effect on the removal of sulfur in coal, but has a great influence on the quality of the coal. In view of the low organic sulfur content in coal, the present invention preferably performs desulfurization under lower temperature conditions and lower voltage conditions, i.e., desulfurization at 320 ℃ and 2.0V, in order to achieve both good desulfurization effect and clean coal yield.

In order to obtain a higher desulfurization rate, a relatively higher temperature and a higher electrolysis potential may be selected. However, the higher electrolytic potential causes the oxidation rate of the electrode to increase, the electrode efficiency gradually decreases as the reaction time increases, thereby affecting the desulfurization rate of coal, and the present inventors have also found that the yield of clean coal tends to decrease as the electrolytic potential increases and the temperature increases. In addition, the oxidation reaction is too active at too high temperature to be controlled, and the influence on the coal quality is difficult to avoid. Therefore, the most preferable organic sulfur removal conditions of the present invention are 320 ℃ and 2.0V.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (10)

1. A method for removing organic sulfur in coal based on solar STEP thermal-electrochemical coupling is characterized by comprising the following STEPs:

(1) pretreating coal to obtain coal powder;

(2) placing a solid material formed by mixing the coal powder and the solid electrolyte in a closed electrolysis device; and

(3) the solid material is electrolyzed at the temperature of 320-380 ℃ and the pressure of 1.8-3.0V, the heat energy required by the electrolysis is provided by a solar heat collecting device, and the electric energy required by the electrolysis is provided by a photovoltaic cell.

2. The method of claim 1,

the electrolysis was carried out at 320 ℃ and 2.0V.

3. The method of claim 1,

the solid electrolyte is powdered sodium hydroxide.

4. The method according to any one of claims 1 to 3,

the mass ratio of the pulverized coal to the solid electrolyte is 1: (10-15), preferably 1: 10.

5. The method according to any one of claims 1 to 4,

the electrolysis adopts a double-electrode system, and the electrodes are all nickel electrodes.

6. The method according to any one of claims 1 to 5,

the solar heat collecting device is a focusing solar heat collector; and

the solar photoelectric conversion device is a polycrystalline silicon photovoltaic cell.

7. The method of claim 6,

and during the electrolysis, the voltage output by the solar photoelectric conversion device is regulated by the voltage stabilizer.

8. The method of claim 6,

the thermal energy provided by the solar thermal collection device is regulated by a temperature controller equipped with a thermocouple.

9. The method according to any one of claims 1 to 8,

the pretreatment comprises the following steps:

(a) crushing coal;

(b) screening the crushed coal;

(c) drying the screened coal; and

(d) and (4) performing deliming treatment on the dried coal.

10. The method of claim 9,

sieving coal below 120 meshes;

drying the screened coal at 40-60 ℃ for 20-24 hours; and/or

The deashing treatment is carried out according to the following method: soaking the dried coal with absolute ethyl alcohol, adding 40% hydrofluoric acid solution, and placing the mixed material in a water bath device at 50-60 deg.C while heating and stirring; filtering the obtained material, cooling, adding 50% hydrochloric acid solution, stirring, filtering, washing and drying in sequence.

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