Synthesis of hydrogen from hydrogen sulfide gas

Abstract

Hydrogen may be generated from hydrogen sulfide by electrochemical reaction. For example, a hydrogen production method by electrochemical reaction may include: flowing an electrical current through a cathode and an anode immersed in an electrolyte solution in an electrolytic cell to produce a zinc-electrolyte hydroxide and hydrogen, where the anode comprises zinc, and where the electrolyte solution comprises an electrolyte at least partially dissolved in water; transferring at least a portion of the zinc-electrolyte hydroxide from the electrolytic cell to an adsorption cell; supplying hydrogen sulfide gas to the adsorption tank; the zinc-electrolyte hydroxide is reacted with a hydrogen sulfide gas to produce solid zinc sulfide and an electrolyte.

Description

Technical Field

[0001] The present disclosure relates generally to the synthesis of hydrogen and, more particularly, to the synthesis of hydrogen from hydrogen sulfide. Background Art

[0002] Hydrogen is an emerging clean fuel source with the potential to power energy storage, electricity production, vehicle propulsion and other applications. Hydrogen can be converted into usable energy (including electricity) in a low-emission or no-emission manner using technologies such as fuel cells, since the product of hydrogen used in fuel cells is water.

[0003] Methane derived from natural gas is the traditional source currently used to produce hydrogen. Traditional hydrogen production methods include steam methane reforming (SMR), autothermal methane reforming (ATR) and partial oxidation of methane (POM). SMR, ATR and POM have the main disadvantage of high CO2 emissions, which offsets the clean combustion advantages of using hydrogen as a fuel source. Other disadvantages of traditional hydrogen production methods include high energy consumption, high cost, low reaction efficiency, low process stability and low catalyst efficiency.

[0004] Hydrogen sulfide (H2S) is generally considered a toxic and corrosive compound and is a byproduct of many petroleum refining processes. Currently, H2S waste is typically processed through the standard Claus process, by which H2S is converted to water and sulfur via a sulfur dioxide (SO2) intermediate at high temperature. Although the Claus process can be highly efficient, residues (including H2S residues) and impurities often remain and are burned to form SO2, requiring additional processing and costs, and can produce large amounts of toxic emissions. Summary of the invention

[0005] The various details of the present disclosure are summarized below to provide a basic understanding. The present disclosure is not an exhaustive overview of the present disclosure, and is neither intended to point out certain elements of the present disclosure nor to describe the scope of the present disclosure. On the contrary, the main purpose of the present disclosure is to present some concepts of the present disclosure in a simplified form before presenting a more detailed description below.

[0006] A first non-limiting method of the present disclosure includes: passing an electric current through a cathode and an anode immersed in an electrolyte solution in an electrolytic cell to produce zinc-electrolyte hydroxide and hydrogen gas, wherein the anode comprises zinc and wherein the electrolyte solution comprises an electrolyte at least partially dissolved in water; transferring at least a portion of the zinc-electrolyte hydroxide from the electrolytic cell to an adsorption cell; supplying hydrogen sulfide gas to the adsorption cell; reacting the zinc-electrolyte hydroxide with the hydrogen sulfide gas to produce solid zinc sulfide and the electrolyte.

[0007] A second non-limiting method of the present disclosure includes: passing an electric current through a cathode and an anode immersed in an electrolyte solution in an electrolytic cell to produce a zinc-electrolyte hydroxide and hydrogen gas, wherein the anode comprises zinc and wherein the electrolyte solution comprises an electrolyte at least partially dissolved in water; transferring at least a portion of the zinc-electrolyte hydroxide from the electrolytic cell to an adsorption cell; supplying hydrogen sulfide gas to the adsorption cell; reacting the zinc-electrolyte hydroxide with the hydrogen sulfide gas to produce solid zinc sulfide and the electrolyte; and reacting the zinc electrolyte in a second electrolyte solution with the hydrogen sulfide gas to produce solid zinc sulfide and an electrolyte, wherein the production of the electrolyte forms a regenerated electrolyte solution in which the electrolyte is at least partially dissolved; and recovering at least a portion of the electrolyte from the adsorption cell to the electrolytic cell.

[0008] A third non-limiting method of the present disclosure comprises: passing an electric current through a cathode and an anode immersed in an electrolyte solution in an electrolytic cell to produce a zinc-electrolyte hydroxide and hydrogen gas, wherein the anode comprises zinc, wherein the electrolyte solution comprises an electrolyte at least partially dissolved in water, wherein the zinc-electrolyte hydroxide comprises Zn(E) x (OH)2, and wherein the electrolyte includes potassium chloride, sodium chloride, ammonium chloride, potassium sulfate, sodium sulfate, ammonium sulfate, ethylenediaminetetraacetic acid (EDTA), ethylenediaminetetraacetic acid disodium salt (EDTA-2Na), ethylenediaminetetraacetic acid tetrasodium salt (EDTA-4Na), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid trisodium salt (HEDTA-3Na), diethylenetriaminepentaacetic acid (DTPA), diethylenetriaminepentaacetic acid pentasodium salt (DTPA-5Na), 1,2-diaminocyclohexanetetraacetic acid (DCTA), 1,2-diaminocyclohexane one or more of disodium salt of deoxydimethylformamide tetraacetate (DCTA-2Na), citric acid, sodium citrate, or any combination thereof; transferring at least a portion of the zinc-electrolyte hydroxide from the electrolytic cell to an adsorption cell; supplying hydrogen sulfide gas to the adsorption cell; reacting the zinc-electrolyte hydroxide with the hydrogen sulfide gas to produce solid zinc sulfide and the electrolyte; reacting the zinc electrolyte in a second electrolyte solution with the hydrogen sulfide gas to produce solid zinc sulfide and the electrolyte, wherein the production of the electrolyte forms a regenerated electrolyte solution in which the electrolyte is at least partially dissolved; and recovering at least a portion of the electrolyte from the adsorption cell to the electrolytic cell.

[0009] Any combination of the various embodiments and implementations disclosed herein may be used in another embodiment consistent with the present disclosure.These and other aspects and features may be understood from the following description of certain embodiments presented herein, in light of the present disclosure and the accompanying drawings and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A diagram of a non-limiting example system of the present disclosure is shown.

[0011] Figure 2 A diagram of a non-limiting example electrolytic cell of the present disclosure is shown.

[0012] Figure 3 A diagram showing a non-limiting example adsorption cell of the present disclosure is shown.

[0013] Figure 4 A graph showing the hydrogen produced and the energy consumed for a fresh electrolyte solution.

[0014] Figure 5 A diagram showing the hydrogen produced and the energy consumed for the first recovery is shown.

[0015] Figure 6 A diagram showing the hydrogen produced and the energy consumed for the second recovery is shown.

[0016] Figure 7 An X-ray diffraction (XRD) pattern of ZnS produced using fresh electrolyte is shown.

[0017] Figure 8 XRD patterns of ZnS produced from the first recycling and the second recycling are shown.

[0018] Fig. 9 Shown is a scanning electron microscope (SEM) image of ZnS produced using fresh electrolyte.

[0019] Fig.10 Shown is a SEM image of ZnS produced from the first recycling.

[0020] Fig.11 Shown is a SEM image of ZnS produced from the second recycling. DETAILED DESCRIPTION

[0021] Embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. For consistency, similar elements may be represented by similar reference numerals in each of the accompanying drawings. In addition, in the following detailed description of the embodiments of the present disclosure, many specific details are set forth to provide a more thorough understanding of the claimed subject matter. However, it is obvious to those skilled in the art that the embodiments disclosed herein may be practiced without these specific details. In other cases, well-known features are not described in detail to avoid unnecessarily complicating the description. In addition, it is obvious to those skilled in the art that the ratio of the elements presented in the accompanying drawings may vary without departing from the scope of the present disclosure.

[0022] Embodiments according to the present disclosure relate generally to the synthesis of hydrogen, and more particularly, to the synthesis of hydrogen from hydrogen sulfide.

[0023] The present disclosure includes methods and systems for producing hydrogen (H2) from hydrogen sulfide (H2S) by using a dual cell system including an electrolytic cell and an adsorption cell. Conventional hydrogen production can produce large amounts of greenhouse gas emissions and require large amounts of raw material cost expenditures. Hydrogen sulfide is generally considered a toxic byproduct, so hydrogen production using hydrogen sulfide makes it possible to process hydrogen sulfide and achieve significant value-added through hydrogen production. In addition, the methods and systems of the present invention make it possible to avoid the use of the Claus process, thereby reducing the emission of toxic impurities and byproducts. In addition, zinc sulfide (ZnS) is produced during the hydrogen production process described in the present disclosure, thereby producing additional value-added products and increasing potential process benefits. In addition, the present disclosure makes it possible to produce nano-sized zinc sulfide, which can have a higher purity, thereby further increasing the potential income from zinc sulfide production.

[0024] The present disclosure may include the use of an apparatus and method for producing hydrogen that includes the use of an electrolysis cell and an adsorption cell that are fluidly connected together. Figure 1 , a diagram of a non-limiting example device 10 including an electrolytic cell 20 and an adsorption cell 30 is shown in . The electrolytic cell 20 may have one or more gas pipelines 21 connected to its fluid for introducing or removing gas (e.g., introducing nitrogen, removing hydrogen). The adsorption cell 30 may have a gas inlet pipeline 31 connected to its fluid for introducing gas (e.g., hydrogen sulfide gas), and may have a solid outlet pipeline 33 for removing solids (e.g., zinc sulfide). The device 10 may also include a system 50 for transferring electrolyte solution between cells. The system 50 may include an electrolytic cell outlet pipeline 52a and an adsorption cell inlet pipeline 52b for transferring solution from the electrolytic cell 20 to the adsorption cell 30, and may also include an adsorption cell outlet pipeline 54a and an electrolytic cell inlet pipeline 54b for transferring solution from the adsorption cell 30 to the electrolytic cell 20.

[0025] Figure 22 shows a diagram of a non-limiting example electrolytic cell. Electrolytic cell 200 may include reaction chamber 210. Electrolytic cell 200 may also include nitrogen inlet line 212 and hydrogen outlet line 214. It should be noted that nitrogen inlet line 212 and hydrogen outlet line 214 may be constructed as a single line, which may be diverted to or from an appropriate destination by a system outside the electrolytic cell. Reaction chamber 210 may have an electrolyte solution 220 in which electrolyte 222 is at least partially dissolved. Electrolyte solution 220 may have a cathode 232 and an anode 234 immersed therein. Cathode 232 and anode 234 may be connected to cathode wire 232a and anode wire 234a, respectively, wherein wires 232a and 234a provide current from power supply 230. During operation of electrolytic cell 200, hydrogen gas 240 may be formed at cathode 232, and zinc-electrolyte hydroxide 242 may be formed in electrolyte solution 220. The electrolytic cell 200 may include an inlet line 250a for introducing a solution (e.g., an electrolyte solution) into the reaction chamber 210. The electrolytic cell 200 may include an outlet line 250b for removing the electrolyte solution from the reaction chamber 210. It should be noted that an electrolytic cell according to the present disclosure may have one or more additional inlets, outlets, or inlets plus outlets for removing, adding, or removing and adding fluids (e.g., gases or electrolyte solutions).

[0026] The adsorption cell can be operated at any suitable pressure, preferably at atmospheric pressure, and can be operated at a temperature of 1°C to 99°C, or 10°C to 50°C, or 20°C to 40°C. The electrolytic cell can be operated at a pH of 6 to 11, or 6.8 to 10.2, or 6.9 to 10.1, or 7 to 11, or 7 to 10. The reaction chamber of the electrolytic cell can be of any suitable size, and the components therein (e.g., cathode, anode, etc.) can be of any suitable size for operation in the electrolytic cell. As a non-limiting example, for an electrolytic cell having an electrolyte solution volume of about 1 liter, the cathode and anode can each have a size of about 50 mm×50 mm, each having a thickness of about 0.2 mm to 0.3 mm.

[0027] The electrolyte solution of the electrolytic cell may include an aqueous fluid and one or more compounds that may at least partially form an electrolyte. The one or more aforementioned compounds may dissociate into one or more constituent substances (e.g., Na + Ion, Cl - Ions, EDTA 4-The invention relates to an aqueous fluid having an electrolyte solution. The aqueous fluid may be a mixture of an aqueous liquid and an organic electrolyte ... Suitable organic electrolytes may include, but are not limited to, ethylenediaminetetraacetic acid (EDTA), ethylenediaminetetraacetic acid disodium salt (EDTA-2Na), ethylenediaminetetraacetic acid tetrasodium salt (EDTA-4Na), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid trisodium salt (HEDTA-3Na), diethylenetriaminepentaacetic acid (DTPA), diethylenetriaminepentaacetic acid pentasodium salt (DTPA)-5Na), 1,2-diaminocyclohexanetetraacetic acid (DCTA), 1,2-diaminocyclohexanetetraacetic acid disodium salt (DCTA-2Na), citric acid, sodium citrate, etc., or any combination thereof. The concentration of the inorganic salt in the electrolyte solution (if present) can be 0.01 mol / L to 10 mol / L (or 0.01 mol / L to 5 mol / L, or 0.01 mol / L to 2 mol / L, or 0.01 mol / L to 1 mol / L, or 0.1 mol / L to 10 mol / L, or 0.1 mol / L to 5 mol / L, or 0.1 mol / L to 2 mol / L, or 0.1 mol / L to 1 mol / L, or 1 mol / L to 5 mol / L, or 1 mol / L to 2 mol / L). The concentration of the organic electrolyte (if present) in the electrolyte solution can be 0.01 mol / L to 10 mol / L (or 0.01 mol / L to 5 mol / L, or 0.01 mol / L to 2 mol / L, or 0.01 mol / L to 1 mol / L, or 0.1 mol / L to 10 mol / L, or 0.1 mol / L to 5 mol / L, or 0.1 mol / L to 2 mol / L, or 0.1 mol / L to 1 mol / L, or 1 mol / L to 5 mol / L, or 1 mol / L to 2 mol / L).

[0028] Before the current is introduced into the electrolytic cell, nitrogen can be introduced into the electrolytic cell to at least partially purge oxygen from the electrolytic cell (including from the electrolyte solution). The nitrogen can be of any suitable purity, including 90 mol% to 99.99 mol%, or greater than 95 mol%. The flow rate of the nitrogen can be any suitable flow rate required to at least partially purge the oxygen, and can depend on factors including, but not limited to, the size of the reaction chamber of the electrolytic cell. The introduction of nitrogen can have a purge time of 15 minutes to 60 minutes, or 15 minutes to 30 minutes, or 25 minutes to 35 minutes.

[0029] As described above, the electrolytic cell can be operated by passing an electric current through a cathode and an anode immersed in an electrolyte solution. The electric current can be provided by a power supply and delivered by a conductor at the anode and cathode. With the benefit of this disclosure, those skilled in the art will appreciate the selection and configuration of suitable power supplies and conductors. The type of electric current can include direct current (DC) or alternating current (AC). DC can be a preferred type of electric current. The electric current can have any suitable voltage, including a voltage of 0.05V to 50V, or 0.1V to 10V, or 0.1V to 5V, or 0.1V to 1V. The electric current can have any suitable amperage, including an amperage of 0.05A to 50A, or 0.1A to 10A, or 0.1A to 5A, or 0.1A to 1A.

[0030] Electrodes (e.g., cathodes and anodes) may include various suitable compositions, including metals, metal oxides, carbon, conductive polymers, semiconductors, and ceramics. Metals include titanium, iron, copper, platinum (iridium or rubidium is added for increased strength), nickel, zinc, tin, and stainless steel. Metal electrodes may be combined with mixed metal oxides (MMOs). Carbon-based electrodes include granular carbon, pretreated natural graphite, and artificial graphite (e.g., carbonized petroleum coke, oil, or coal tar pitch). The anode may preferably include zinc or a zinc alloy. The cathode may preferably include titanium or a titanium alloy.

[0031] The method may also include reacting the electrolyte and zinc of the anode to produce hydrogen and zinc-electrolyte hydroxide, wherein the zinc-electrolyte hydroxide may be at least partially dissolved in the electrolyte solution. The zinc-electrolyte hydroxide may include a zinc-hydroxide complex. Without being bound by theory, the above reaction may occur as a result of the current flowing in the electrolytic cell. In addition, it should be noted that the reaction may cause the anode (e.g., an anode comprising zinc) to dissolve into the electrolyte solution, and the reaction may cause the cathode to be plated with material (e.g., zinc) from the electrolyte solution. As a result, the cathode and the anode may each need to be replaced at periodic intervals.

[0032] The above reactions in the electrolytic cell may occur according to the reactions listed below, wherein reaction formula 1 occurs at the anode, reaction formula 2 occurs at the cathode, and reaction formula 3 is the overall reaction.

[0033] Anode: Zn+xE→Zn(E) x 2+ +2e - Reaction 1

[0034] Cathode: 2H2O+2e - →2OH - +H2↑ Reaction 2

[0035] Overall: Zn+xE+2H2O→Zn(E) x (OH)2+2H2↑ Reaction 3

[0036] Among them, Zn(E) x (OH)2 is a zinc-hydroxide complex, where E represents an electrolyte, and where x represents the relative atomic number of the electrolyte. The relative atomic number x may depend on the specific electrolyte present in the reaction. As a non-limiting example, if the electrolyte includes Na + and Cl - , then the relative atomic number can be 1.

[0037] The hydrogen produced in the above reaction can be any purity, including 10mol% to 99.99mol%, or 50mol% to 99.99mol%, or 90mol% to 99.99mol%, or 90mol% to 99mol%, or greater than 90mol%, or greater than 95mol%. The hydrogen can then be captured and transported for storage using suitable methods and devices. After the hydrogen is generated in the electrolytic cell, it can undergo further processing, including, for example, purification. Hydrogen can also be used to generate electricity, including using fuel cells to generate electricity.

[0038] The methods of the present disclosure may include transferring at least a portion of the electrolyte solution from the electrolytic cell to the adsorption cell, including transferring at least a portion of the zinc-electrolyte hydroxide from the electrolytic cell to the adsorption cell. Figure 3A non-limiting example adsorption cell is shown in FIG. The adsorption cell 300 may include a reaction chamber 310. The adsorption cell 300 may also have a hydrogen sulfide inlet line 312 fluidly connected thereto, through which hydrogen sulfide gas 346 is introduced into an electrolyte solution 320 in the reaction chamber 310. The electrolyte solution 320 may include a zinc-electrolyte hydroxide 342 at least partially dissolved therein. The zinc-electrolyte hydroxide 342 may react with the hydrogen sulfide gas 346 to produce solid zinc sulfide 348 and an electrolyte 322, wherein the electrolyte 322 may be at least partially dissolved in the electrolyte solution 320. The adsorption cell 300 may also have a solid outlet 314, through which the solid zinc sulfide 348 may be removed. The adsorption cell 200 may include an inlet line 350a for introducing a solution (e.g., an electrolyte solution) into the reaction chamber 310. The adsorption cell 300 may include an outlet line 350b for removing a solution (e.g., an electrolyte solution) from the reaction chamber 310. It should be noted that an adsorption cell according to the present disclosure may have one or more additional inlets, outlets, or inlets plus outlets for removing, adding, or removing and adding fluids (e.g., gases or electrolyte solutions).

[0039] The adsorption cell can be operated at any suitable pressure, preferably at atmospheric pressure, and can be operated at a temperature of 1° C. to 99° C., or 10° C. to 50° C., or 20° C. to 40° C. The adsorption cell can be operated at a pH of 6 to 11, or 6.8 to 10.2, or 6.9 to 10.1, or 7 to 11, or 7 to 10. The reaction chamber for the adsorption cell can be of any suitable size, and the components therein can be of any suitable size for operation within the adsorption cell.

[0040] The present disclosure may include the operation of the above-mentioned adsorption cell, including supplying hydrogen sulfide to the electrolyte solution in the adsorption cell, and reacting zinc-electrolyte hydroxide with hydrogen sulfide. The flow rate of hydrogen sulfide can be any suitable flow rate, and can depend on factors including but not limited to the size of the adsorption cell, the concentration of the electrolyte in the solution, etc., or any combination thereof. The hydrogen sulfide supplied to the adsorption cell can have any suitable purity, including 80mol% to 99.99mol%, or 90mol% to 99.99mol%, or greater than 95mol%. It should be noted that the purity of hydrogen sulfide can vary depending on the feed supply. Since hydrogen sulfide is usually a byproduct, the purity can depend on the source process. The source of hydrogen sulfide can be any suitable source, including but not limited to a well, another refining process, etc., or any combination thereof.

[0041] The reaction of zinc-electrolyte hydroxide and hydrogen sulfide to form zinc sulfide and electrolyte can be carried out according to the reaction in the following reaction formula 4.

[0042] Zn(E) x(OH)2+H2S→ZnS↓+2H2O+xE Reaction 4

[0043] A portion of the electrolyte solution of the adsorption cell may be filtered to recover the solid zinc sulfide. After removal from the solution, the solid zinc sulfide may be heated, dried, or otherwise further processed to purify the zinc sulfide. The solid zinc sulfide prepared according to the present disclosure may comprise nano-sized zinc sulfide fine particles having a number average diameter of 10 nm to 1000 nm, or 10 nm to 500 nm, or 50 nm to 500 nm, or 50 nm to 200 nm.

[0044] The generation of electrolyte in the adsorption cell can regenerate the electrolyte solution. At least a portion of the electrolyte solution regenerated in the adsorption cell can be recycled to the electrolytic cell.

[0045] The above system can be operated in a continuous mode, a batch mode or a combination thereof.

[0046] In batch operation, the transfer of electrolyte solution can occur intermittently at discontinuous intervals. As a non-limiting example, when a batch is completed in the electrolytic cell (in batch operation), the electrolyte solution can be transferred to the adsorption cell. The completion of a batch in the electrolytic cell can be determined by factors including but not limited to the pH of the electrolyte solution, the hydrogen produced, the temperature of the pool, etc., or any combination thereof. The completion of a batch in the adsorption pool can be determined by factors including but not limited to the pH of the electrolyte solution, the hydrogen sulfide gas consumed, the zinc sulfide produced, the temperature of the pool, etc., or any combination thereof. When operated in a batch mode, the transfer of electrolyte solution from the electrolytic cell to the adsorption cell and the subsequent recovery from the adsorption cell to the electrolytic cell constitute one (1) recovery cycle. The system can experience 1 to 100, or greater than 1, or greater than 3, or greater than 5, or greater than 10, or greater than 100 recovery cycles. The number of cycles beyond the expected range is also considered in addition. Between recovery cycles, electrolyte solution can be added, electrolyte solution or a combination thereof can be removed.

[0047] In continuous operation, the electrolyte solution may flow between the electrolytic cell and the adsorption cell, between the adsorption cell and the electrolytic cell, or in a continuous manner in both directions. As a non-limiting example, the electrolyte solution may flow from the electrolytic cell to the adsorption cell in a continuous loop and then be recycled back to the electrolytic cell. It is also contemplated that in continuous operation, a feed of fresh electrolyte solution may flow to either cell and electrolyte solution may be removed from either cell, but it should be noted that operation requires neither continuous feed nor continuous removal.

[0048] In some cases, the system can be operated in a combination of continuous and batch modes. As a non-limiting example, the system can be operated continuously for a period of time with electrolyte solution flowing from the electrolytic cell to the adsorption cell and from the adsorption cell to the electrolytic cell until a batch is completed, at which time the system will be reconfigured with fresh electrolyte for a new batch. As another non-limiting example, the system can be operated so that the transfer of electrolyte solution from the electrolytic cell to the adsorption cell can occur in a batch mode, and the transfer of electrolyte solution from the adsorption cell to the electrolytic cell can occur in a continuous mode.

[0049] For purposes of these simplified schematic illustrations and descriptions, there may be additional valves, lines, pumps, sensors, controllers, etc. that are commonly used in electrochemical operations (e.g., electrolytic cell operations or adsorption cell operations) that are well known to those skilled in the art but are not shown.

[0050] Example

[0051] Test calculation method

[0052] The H2 production rate v (volume per unit time) is calculated by equation (5):

[0053]

[0054] Where m i is the initial mass of the zinc plate (g); m e is the final mass of the zinc plate after the experiment (g); M zn is the molecular weight of zinc (g / mol); t is the length of time between the initial and final readings; V m is the standard volume of gas (about 22.4 L / mol). The energy consumption EC (Kwh / m 3 ):

[0055]

[0056] where V is the set voltage of the electrolysis (volts); A is the recorded current (amperes); and v is the H2 production rate (L / hr).

[0057] Experiment 1 - Hydrogen Generation

[0058] The electrolysis reaction was carried out in a prepared electrolyte solution containing 1.2 mol / L KCl and 0.2 mol / L EDTA-2Na in 1 L of deionized water at 25°C, wherein the pH was adjusted to 7 (pH was adjusted by adding NaOH). The dissolved oxygen in the solution and the air in the system were purged with nitrogen for 30 minutes. The current of the DC power supply was set to 1 ampere. A zinc plate (dimensions of 50 mm×50 mm×0.25 mm) was used as an anode and dissolved as the reaction proceeded. A titanium plate (dimensions of 50 mm×50 mm×0.2 mm) was used as a cathode, and H2 bubbles were generated as the reaction proceeded. The resulting solution was transparent, indicating that the zinc-hydroxide complex (Zn(E) x (OH)2) has good solubility. The reaction is carried out until the pH reaches 10. Figure 4 As shown, the average H2 production rate is about 0.46L / hr and the energy consumption is about 2.55Kwh / m 3 .

[0059] Experiment 2 - Electrolyte Generation

[0060] The resulting zinc-hydroxide solution with electrolyte formed in Experiment 1 was then transferred to a 2000 ml three-necked flask with magnetic stirring at 25°C. 1 mol / L Na2S solution and 1 mol / L H2SO4 were simultaneously added dropwise to the resulting solution to excite H2S gas. The dropwise addition rate of the solution was adjusted to 100 ml / hr to synthesize nano-sized ZnS. When the pH value of the solution reached 7, the dropwise addition of Na2S solution and H2SO4 solution was stopped. The solution was continuously stirred at 25°C for 2 hours to obtain a regenerated electrolyte and a precipitate. After the reaction was completed, the precipitate was filtered out and dried in an oven at 120°C for 24 hours to obtain a light yellow powder containing ZnS. The regenerated electrolyte solution was collected for subsequent electrolysis.

[0061] Experiment 3 - First Recycling

[0062] The regenerated electrolyte solution from Experiment 2 was used to generate H2 by electrolysis according to the procedure of Experiment 1. Figure 5 As shown in the figure, the H2 production rate is about 0.46L / hr and the energy consumption is about 3.03Kwh / m 3 As shown in the figure, the results show that the electrolyte can be effectively recycled for H2 generation, indicating that a recyclable system has been established. The solution was subsequently recycled according to the procedure of Experiment 2 to obtain a regenerated electrolyte solution ("first recycling") and obtain ZnS.

[0063] Experiment 4 - Second Retrieval

[0064] The regenerated electrolyte solution from Experiment 3 was used to generate H2 by electrolysis according to the procedure of Experiment 1. The H2 production rate and energy consumption are shown in Figure 6 As shown in the figure, the results show that the electrolyte can be effectively recycled for H2 generation, indicating that a recyclable system has been established. The solution was subsequently recycled according to the procedure of Experiment 2 to obtain a regenerated electrolyte solution ("secondary recycling") and ZnS.

[0065] Characterization of ZnS

[0066] The X-ray diffraction (XRD) pattern of the synthesized ZnS (from Experiment 2) is shown in Figure 7 The structural parameters obtained by XRD measurement are listed in Table 1 below. Three main diffraction peaks were observed at 28.67 °, 47.64 ° and 56.61 °, which correspond to the (111), (220) and (311) crystal planes of cubic ZnS, respectively. By comparing with the ZnS standard card (JCPDS, No.05-0566), it can be identified as a cubic sphalerite structure. The XRD diagram shows that there is no diffraction peak, because such a peak will indicate crystalline impurities. Due to the small particle size of the sample, the peak is significantly broadened, which shows that nano-sized ZnS has been successfully synthesized. The average grain size of the prepared ZnS is about 6.40nm.

[0067] Table 1 Structural parameters of synthesized ZnS (Experiment 2)

[0068]

[0069] The XRD analysis was repeated for ZnS from the first and second recovery (Experiments 3 and 4, respectively). Figure 8 The XRD patterns of the products synthesized in the first and second recycling are shown. The structural parameters obtained from the XRD measurements of the first and second recycling are listed in Tables 2 and 3 below, respectively.

[0070] Table 2 Structural parameters of ZnS synthesized in the first recovery (Experiment 3)

[0071]

[0072] Table 3 Structural parameters of ZnS synthesized in the second recovery (Experiment 4)

[0073]

[0074] The results show that the synthesized product from the recycling is cubic ZnS with nano-sized particles ranging from about 6.71 nm to about 6.91 nm. The results show that the electrolyte can be recycled for hydrogen generation and preparation of high-purity nano-sized ZnS.

[0075] Furthermore, the produced ZnS was characterized by scanning electron microscopy (SEM). Fig. 9SEM images of nano-sized ZnS from Experiment 2 are shown. The nanoparticles are present in the form of clusters. The surface morphology of the clusters is a cauliflower-like structure. The particle size of the clusters is about 50 nm to about 200 nm.

[0076] Fig.10 and Fig.11 SEM images of nano-sized ZnS from Experiments 3 and 4 (first recovery and second recovery) are shown, respectively. Here, cauliflower-like clusters of the product are shown, with a particle size of about 50 nm to about 200 nm. The results show that there is no significant difference between the recovered synthetic products (Experiments 3 and 4) and the products obtained with fresh electrolyte (Experiment 2). The results show that nano-sized ZnS products can be obtained using regenerated electrolytes.

[0077] Other embodiments

[0078] Embodiments disclosed herein include:

[0079] Embodiment 1. A method comprising: passing an electric current through a cathode and an anode immersed in an electrolyte solution in an electrolytic cell to produce zinc-electrolyte hydroxide and hydrogen gas, wherein the anode comprises zinc and wherein the electrolyte solution comprises an electrolyte at least partially dissolved in water; transferring at least a portion of the zinc-electrolyte hydroxide from the electrolytic cell to an adsorption cell; supplying hydrogen sulfide gas to the adsorption cell; reacting the zinc-electrolyte hydroxide with the hydrogen sulfide gas to produce solid zinc sulfide and an electrolyte.

[0080] Embodiment 2. The method according to embodiment 1 further comprises recycling at least a portion of the electrolyte from the adsorption cell to the electrolysis cell.

[0081] Embodiment 3. The method of embodiment 1 or 2, wherein the zinc-electrolyte hydroxide comprises a zinc-hydroxide complex, and wherein the zinc-hydroxide complex comprises Zn(E) x (OH)2, wherein E represents an electrolyte, and wherein x represents the relative atomic number of the electrolyte.

[0082] Embodiment 4. The method according to any one of embodiments 1 to 3, wherein the electrolyte solution comprises an aqueous fluid and one or more of an inorganic salt, an organic electrolyte or any combination thereof.

[0083] Embodiment 5. The method according to embodiment 4, wherein the inorganic salt comprises potassium chloride, sodium chloride, ammonium chloride, potassium sulfate, sodium sulfate, ammonium sulfate or any combination thereof.

[0084] Example 6. A method according to Example 4, wherein the organic electrolyte includes ethylenediaminetetraacetic acid (EDTA), ethylenediaminetetraacetic acid disodium salt (EDTA-2Na), ethylenediaminetetraacetic acid tetrasodium salt (EDTA-4Na), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid trisodium salt (HEDTA-3Na), diethylenetriaminepentaacetic acid (DTPA), diethylenetriaminepentaacetic acid pentasodium salt (DTPA)-5Na), 1,2-diaminocyclohexanetetraacetic acid (DCTA), 1,2-diaminocyclohexanetetraacetic acid disodium salt (DCTA-2Na), citric acid, sodium citrate or any combination thereof.

[0085] Embodiment 7. A method according to Embodiment 4, wherein: a) if present, the first concentration of the inorganic salt in the electrolyte solution is 0.01 mol / L to 10 mol / L; b) if present, the second concentration of the organic electrolyte in the electrolyte solution is 0.01 mol / L to 10 mol / L; or c) both a and b are present.

[0086] Embodiment 8. The method of any one of embodiments 1 to 7, further comprising introducing nitrogen gas into the electrolytic cell to at least partially purge oxygen from the electrolyte solution prior to flowing the current.

[0087] Embodiment 9. The method according to embodiment 8, wherein the purge time of introducing nitrogen is 15 minutes to 60 minutes.

[0088] Embodiment 10. The method according to any one of embodiments 1 to 9, further comprising filtering at least a portion of the electrolyte solution from the adsorption cell to recover solid zinc sulfide.

[0089] Embodiment 11. The method of any one of embodiments 1 to 10, wherein causing the current to flow comprises causing direct current to flow, and wherein the direct current has a voltage of 0.1V to 10V and an amperage of 0.1A to 10A.

[0090] Embodiment 12. The method of any one of embodiments 1 to 11, wherein the cathode comprises titanium.

[0091] Embodiment 13. The method of any one of embodiments 1 to 12, wherein the adsorption cell is at a first temperature, and wherein the electrolysis cell is at a second temperature, and wherein both the first temperature and the second temperature are 20°C to 40°C.

[0092] Embodiment 14. The method of any one of embodiments 1 to 13, wherein the solid zinc sulfide comprises fine particles, and wherein the fine particles have a number average diameter of 50 nm to 200 nm.

[0093] Embodiment 15. The method of any one of embodiments 1 to 14, wherein the electrolytic cell is operated at a pH of 7 to 11.

[0094] Embodiment 16. The method according to any one of embodiments 1 to 15, wherein the adsorption cell is operated at a pH of 7 to 11.

[0095] Embodiment 17. The method of any one of embodiments 1 to 16, wherein the transfer of at least a portion of the zinc-electrolyte hydroxide from the electrolytic cell to the adsorption cell is performed in a batch mode.

[0096] Embodiment 18. The method of any one of embodiments 1 to 17, wherein the transferring of at least a portion of the zinc-electrolyte hydroxide from the electrolytic cell to the adsorption cell comprises transferring at least a portion of the electrolyte solution from the electrolytic cell to the adsorption cell.

[0097] Embodiment 19. The method according to any one of embodiments 1 to 18, wherein the hydrogen has a purity of 90 mol% or higher.

[0098] Embodiment 20. The method of any one of embodiments 1 to 19, further comprising reacting the hydrogen in a fuel cell to generate electricity.

[0099] Embodiment 21. A method comprising: passing an electric current through a cathode and an anode immersed in an electrolyte solution in an electrolytic cell to produce zinc-electrolyte hydroxide and hydrogen gas, wherein the anode comprises zinc and wherein the electrolyte solution comprises an electrolyte at least partially dissolved in water; transferring at least a portion of the zinc-electrolyte hydroxide from the electrolytic cell to an adsorption cell; supplying hydrogen sulfide gas to the adsorption cell; reacting the zinc-electrolyte hydroxide with the hydrogen sulfide gas to produce solid zinc sulfide and an electrolyte; and reacting the zinc electrolyte in a second electrolyte solution with the hydrogen sulfide gas to produce solid zinc sulfide and an electrolyte, wherein the production of the electrolyte forms a regenerated electrolyte solution in which the electrolyte is at least partially dissolved; and recovering at least a portion of the electrolyte from the adsorption cell to the electrolytic cell.

[0100] Embodiment 22. A method comprising: passing an electric current through a cathode and an anode immersed in an electrolyte solution in an electrolytic cell to produce zinc-electrolyte hydroxide and hydrogen gas, wherein the anode comprises zinc, wherein the electrolyte solution comprises an electrolyte at least partially dissolved in water, wherein the zinc-electrolyte hydroxide comprises Zn(E) x(OH)2, and wherein the electrolyte includes potassium chloride, sodium chloride, ammonium chloride, potassium sulfate, sodium sulfate, ammonium sulfate, ethylenediaminetetraacetic acid (EDTA), ethylenediaminetetraacetic acid disodium salt (EDTA-2Na), ethylenediaminetetraacetic acid tetrasodium salt (EDTA-4Na), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid trisodium salt (HEDTA-3Na), diethylenetriaminepentaacetic acid (DTPA), diethylenetriaminepentaacetic acid pentasodium salt (DTPA-5Na), 1,2-diaminocyclohexanetetraacetic acid (DCTA), 1,2-diaminocyclohexane tetraacetic acid disodium salt (DCTA-2Na), citric acid, sodium citrate or any combination thereof; transferring at least a portion of the zinc-electrolyte hydroxide from the electrolytic cell to the adsorption cell; supplying hydrogen sulfide gas to the adsorption cell; reacting the zinc-electrolyte hydroxide with the hydrogen sulfide gas to produce solid zinc sulfide and an electrolyte; reacting the zinc electrolyte in a second electrolyte solution with the hydrogen sulfide gas to produce solid zinc sulfide and an electrolyte, wherein the production of the electrolyte forms a regenerated electrolyte solution in which the electrolyte is at least partially dissolved; and recovering at least a portion of the electrolyte from the adsorption cell to the electrolytic cell.

[0101] The terms used in this disclosure are only for the purpose of describing specific embodiments, not for limiting the present invention. For example, as used in this disclosure, the singular forms "a", "an", and "the" are intended to include plural forms as well, unless the context clearly indicates otherwise. It should also be understood that when used in this specification, the terms "comprise", "contain", and / or "include" and their variations specify the presence of the features, integers, steps, operations, elements, and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, and / or groups thereof.

[0102] The directional terms used in the present disclosure are for convention and reference purposes only and should not be interpreted as limiting. However, it should be recognized that these terms may be used with reference to an operator or user. Therefore, no limitation is implied or inferred. In addition, the use of ordinal numbers (e.g., first, second, third, etc.) is for distinction rather than counting. For example, the use of "third" does not mean that there must be a corresponding "first" or "second". In addition, if used in the present disclosure, the term "coupled" or "coupled to" or "connected" or "connected to" or "attached" or "attached to" may indicate the establishment of a direct or indirect connection, and is not limited to any one, unless so explicitly mentioned.

[0103] Although the present disclosure has described several exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and that elements thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. In addition, it will be understood by those skilled in the art that many modifications may be made to adapt specific instruments, situations or materials to the embodiments of the present disclosure without departing from the essential scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed or the best mode for implementing the present invention, but the present invention will include all embodiments falling within the scope of the appended claims. In addition, references in the appended claims to a device or system or a component of a device or system adapted to, arranged to, capable of, configured to, enabled to, operable to, or operable to perform a specific function will include the device, system or component, whether or not it or the specific function is activated, turned on or unlocked, as long as the device, system or component is so adapted, arranged, capable of, configured to, enabled to, operable or operable.

Claims

1. A method comprising: passing an electric current through a cathode and an anode immersed in an electrolyte solution in an electrolytic cell to produce zinc-electrolyte hydroxide and hydrogen gas, wherein the anode comprises zinc and wherein the electrolyte solution comprises an electrolyte at least partially dissolved in water; transferring at least a portion of the zinc-electrolyte hydroxide from the electrolytic cell to an adsorption cell; supplying hydrogen sulfide gas to the adsorption cell; and The zinc-electrolyte hydroxide is reacted with the hydrogen sulfide gas to produce solid zinc sulfide and the electrolyte.

2. The method of claim 1, further comprising recycling at least a portion of the electrolyte from the adsorption cell to the electrolysis cell.

3. The method according to claim 1, wherein: The zinc-electrolyte hydroxide comprises a zinc-hydroxide complex, and wherein the zinc-hydroxide complex comprises Zn(E) x (OH)2, wherein E represents the electrolyte, and wherein x represents the relative atomic number of the electrolyte.

4. The method according to claim 1, wherein: The electrolyte solution includes an aqueous fluid and one or more of an inorganic salt, an organic electrolyte, or any combination thereof.

5. The method according to claim 4, wherein: The inorganic salt includes potassium chloride, sodium chloride, ammonium chloride, potassium sulfate, sodium sulfate, ammonium sulfate or any combination thereof.

6. The method according to claim 4, wherein: The organic electrolyte includes ethylenediaminetetraacetic acid (EDTA), ethylenediaminetetraacetic acid disodium salt (EDTA-2Na), ethylenediaminetetraacetic acid tetrasodium salt (EDTA-4Na), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid trisodium salt (HEDTA-3Na), diethylenetriaminepentaacetic acid (DTPA), diethylenetriaminepentaacetic acid pentasodium salt (DTPA)-5Na), 1,2-diaminocyclohexanetetraacetic acid (DCTA), 1,2-diaminocyclohexanetetraacetic acid disodium salt (DCTA-2Na), citric acid, sodium citrate or any combination thereof.

7. The method according to claim 4, wherein: a) if present, the first concentration of the inorganic salt in the electrolyte solution is 0.01 mol / L to 10 mol / L; b) if present, the second concentration of the organic electrolyte in the electrolyte solution is 0.01 mol / L to 10 mol / L; or c) Both a and b are met.

8. The method of claim 1, further comprising introducing nitrogen gas into the electrolytic cell to at least partially purge oxygen from the electrolyte solution prior to flowing the electrical current.

9. The method according to claim 8, wherein: The purge time for introducing nitrogen gas is 15 minutes to 60 minutes.

10. The method of claim 1, further comprising filtering at least a portion of the electrolyte solution from the adsorption cell to recover the solid zinc sulfide.

11. The method according to claim 1, wherein: Causing the current to flow includes causing direct current to flow, and wherein the direct current has a voltage of 0.1V to 10V and an amperage of 0.1A to 10A.

12. The method according to claim 1, wherein: The cathode comprises titanium.

13. The method according to claim 1, wherein: The adsorption cell is at a first temperature, and wherein the electrolysis cell is at a second temperature, and wherein both the first temperature and the second temperature are between 20°C and 40°C.

14. The method according to claim 1, wherein: The solid zinc sulfide includes fine particles, and wherein the fine particles have a number average diameter of 50 nm to 200 nm.

15. The method of claim 1, wherein the electrolytic cell is operated at a pH of 7 to 11.

16. The method of claim 1, wherein the adsorption cell is operated at a pH of 7 to 11.

17. The method according to claim 1, wherein: The transfer of at least a portion of the zinc-electrolyte hydroxide from the electrolytic cell to the adsorption cell is performed in a batch mode.

18. The method according to claim 1, wherein: The transfer of at least a portion of the zinc-electrolyte hydroxide from the electrolytic cell to the adsorption cell includes transferring at least a portion of the electrolyte solution from the electrolytic cell to the adsorption cell.

19. A method comprising: passing an electric current through a cathode and an anode immersed in an electrolyte solution in an electrolytic cell to produce zinc-electrolyte hydroxide and hydrogen gas, wherein the anode comprises zinc and wherein the electrolyte solution comprises an electrolyte at least partially dissolved in water; transferring at least a portion of the zinc-electrolyte hydroxide from the electrolytic cell to an adsorption cell; supplying hydrogen sulfide gas to the adsorption tank; reacting the zinc-electrolyte hydroxide with the hydrogen sulfide gas to produce solid zinc sulfide and the electrolyte; reacting the zinc electrolyte in the second electrolyte solution with the hydrogen sulfide gas to produce solid zinc sulfide and the electrolyte, wherein the production of the electrolyte forms a regenerated electrolyte solution in which the electrolyte is at least partially dissolved; and At least a portion of the electrolyte is recovered from the adsorption cell to the electrolysis cell.

20. A method comprising: Passing an electric current through a cathode and an anode immersed in an electrolyte solution in an electrolytic cell to produce zinc-electrolyte hydroxide and hydrogen gas, wherein the anode comprises zinc, wherein the electrolyte solution comprises an electrolyte at least partially dissolved in water, wherein the zinc-electrolyte hydroxide comprises Zn(E) x (OH)2, and wherein the electrolyte comprises one or more of potassium chloride, sodium chloride, ammonium chloride, potassium sulfate, sodium sulfate, ammonium sulfate, ethylenediaminetetraacetic acid (EDTA), ethylenediaminetetraacetic acid disodium salt (EDTA-2Na), ethylenediaminetetraacetic acid tetrasodium salt (EDTA-4Na), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid trisodium salt (HEDTA-3Na), diethylenetriaminepentaacetic acid (DTPA), diethylenetriaminepentaacetic acid pentasodium salt (DTPA-5Na), 1,2-diaminocyclohexanetetraacetic acid (DCTA), 1,2-diaminocyclohexanetetraacetic acid disodium salt (DCTA-2Na), citric acid, sodium citrate, or any combination thereof; transferring at least a portion of the zinc-electrolyte hydroxide from the electrolytic cell to an adsorption cell; supplying hydrogen sulfide gas to the adsorption tank; reacting the zinc-electrolyte hydroxide with the hydrogen sulfide gas to produce solid zinc sulfide and the electrolyte; reacting the zinc electrolyte in the second electrolyte solution with the hydrogen sulfide gas to produce solid zinc sulfide and the electrolyte, wherein the production of the electrolyte forms a regenerated electrolyte solution in which the electrolyte is at least partially dissolved; and At least a portion of the electrolyte is recovered from the adsorption cell to the electrolysis cell.

Images