A co-production method for safe online hydrogen production from electrocatalytic methanol coupled with hydrosulfite preparation

Abstract

The present invention discloses a method for the co-production of electrocatalytic methanol safe online hydrogen production coupled with the preparation of hydrosulfur powder. The by-product sodium formate generated by the electrocatalytic methanol hydrogen production and the remaining methanol alkali solution are directly used as the raw materials for the preparation of hydrosulfur powder. By regulating the raw material ratio and reaction process control of the electrocatalytic methanol hydrogen production, the replacement of the electrolyte when the electrocatalytic methanol hydrogen production reaction proceeds to any extent can ensure that the hydrogen production waste liquid is efficiently used for the production of hydrosulfur powder, and always maintain a high hydrogen production rate at a high reactant concentration and a low overpotential, which greatly reduces the waste of raw materials and can obtain high-purity hydrogen and high-value-added hydrosulfur powder. Compared with traditional high-temperature methanol reforming hydrogen production and water electrolysis hydrogen production, the co-production process of electrocatalytic methanol safe online hydrogen production coupled with the preparation of hydrosulfur powder proposed in the present invention has the characteristics of high resource utilization, strong safety, low cost, etc., which will help promote the large-scale green and safe preparation and application of hydrogen energy.

Description

Technical field:

[0001] The present invention relates to the field of energy and chemical technology, and in particular to a method for co-producing safe online hydrogen production from electrocatalytic methanol coupled with the preparation of hydrosulfur powder. Background technology:

[0002] Safe online hydrogen production from electrocatalytic methanol offers significant advantages and enormous potential compared to traditional hydrogen production methods such as high-temperature methanol reforming and water electrolysis. It combines the low cost of traditional fossil fuel hydrogen production with the high purity of water electrolysis, while fundamentally avoiding the explosive nature of hydrogen and oxygen mixing. The equipment is simple, requiring no diaphragms or hydrogen compressors, and can deliver high-purity hydrogen at high pressure, enabling immediate use and eliminating the challenges of hydrogen storage and transportation. During the electrocatalytic hydrogen production process, the concentration of the byproduct sodium formate in the electrolyte increases while the concentrations of methanol and alkali decrease. This not only affects hydrogen production efficiency but also generates large amounts of wastewater containing sodium formate, excess methanol, and alkali, resulting in wasted resources and increased production costs. On the other hand, the sodium formate byproduct and the excess methanol-alkali produced during electrocatalytic methanol hydrogen production are precisely the raw materials for the sodium formate method to produce hydrosulfur powder. Summary of the invention:

[0003] The present invention provides a co-production method for safe online hydrogen production from electrocatalytic methanol coupled with the preparation of sodium hydroxide. Sodium formate, a by-product of the electrocatalytic methanol hydrogen production, and the remaining methanol alkali liquor are used as raw materials for preparing the sodium hydroxide. By regulating the raw material ratio and reaction process control of the electrocatalytic methanol hydrogen production, the electrocatalytic methanol hydrogen production and the sodium hydroxide production are coupled. This method can ensure that the hydrogen production waste liquid can be efficiently used for sodium hydroxide production at any reaction degree by replacing the electrolyte. This method allows the electrocatalytic methanol hydrogen production to always maintain a high hydrogen production rate at a higher reactant concentration and a lower overpotential, greatly reduces raw material waste, and obtains high-purity hydrogen and high-value-added sodium hydroxide.

[0004] The present invention is achieved through the following technical solutions:

[0005] A method for co-producing electrocatalytic methanol safe online hydrogen production coupled with sodium formate sodium sulfate preparation, comprising the following steps:

[0006] (1) A methanol-alkali solution is placed in a sealed electrolytic cell, and a voltage is applied to the catalytic electrode to produce hydrogen online; the concentrations of reactants and products in the process of electrocatalytic methanol hydrogen production are monitored online in real time, and after the reaction proceeds to a certain extent, the hydrogen production reaction waste liquid is drawn out, and the methanol-alkali solution is added to the hydrogen production electrolytic cell to maintain a dynamic balance of the concentrations of reactants and products in the electrolytic cell; preferably, the methanol-alkali solution is a mixed solution of methanol and sodium hydroxide, and the molar ratio thereof is 0.2 to 2.

[0007] (2) introducing the waste liquid from the hydrogen production reaction into the synthesis reactor of the sodium hypochlorite production line, and introducing sulfur dioxide into the synthesis reactor according to the volume of the waste liquid from the hydrogen production reaction and the concentration of each component, and stirring evenly; controlling the pH by automatically adjusting the sulfur dioxide feeding rate, controlling the reaction temperature by a heating device, and controlling the pressure in the reactor to be constant; after the addition is completed, maintaining the temperature for a period of time before discharging the material;

[0008] (3) Sulphite is obtained through precipitation, filtration, washing, drying and other steps, and the waste liquid obtained from the production of sulphite is treated with methanol for recovery. The obtained methanol is reused in the electrocatalytic production of methanol to produce hydrogen, or is continued to be used as a solvent for the production of sulphite, thereby realizing the recycling of materials.

[0009] Preferably, the methanol alkaline solution in step (1) is a mixed solution of methanol and sodium hydroxide in a molar ratio of 0.2 to 2, and the amount thereof fed into the electrolytic cell is determined according to the size and capacity of the single cell of the electrolytic cell and the number of electrolytic cells; the catalytic electrode for electrocatalytic methanol to hydrogen production is a nickel electrode.

[0010] Preferably, taking a single-tank electrolytic cell with a capacity of 1000 L as an example, the amount of methanol alkaline solution added is 300 to 1000 L.

[0011] Preferably, the electrocatalytic methanol-to-hydrogen reaction level in the electrolyzer is maintained at 20% to 80%. The electrolyte renewal rate is determined by the concentration of the methanol alkaline solution and the hydrogen production rate. By controlling the electrolyte renewal rate, the reactant concentration in the electrolyzer is maintained constant at 0.8 to 3.2 mol / L. The main components of the wastewater from the electrocatalytic methanol-to-hydrogen reaction are sodium formate, methanol, and sodium hydroxide.

[0012] Preferably, in step (2), the temperature in the synthesis reactor of the sodium hydrosulfite production line is maintained at 70-90°C.

[0013] Preferably, the pressure in the synthesis reactor of the sodium hydrosulfite production line is maintained at 0.1-0.4 MPa.

[0014] Preferably, the pH in the synthesis reactor of the sodium hydrosulfite production line is maintained at 4.3 to 4.5.

[0015] Preferably, the reaction time in the synthesis reactor of the sodium hydrosulfite production line is 40 to 100 minutes.

[0016] Preferably, the finally produced insurance powder is not limited to the powder form, but can also be made into insurance powder slurry and supplied to the demand side.

[0017] Preferably, the electrocatalytic methanol hydrogen production process and the sodium hypochlorite production process are continuous, that is, the hydrogen production waste liquid is directly supplied to the sodium hypochlorite production line, or split, that is, the hydrogen production waste liquid is first stored and then transported to the sodium hypochlorite production line.

[0018] The beneficial effects of the present invention are as follows: The present invention provides a co-production method for the safe online hydrogen production from electrocatalytic methanol coupled with the preparation of insurance powder, wherein the by-product sodium formate generated by the electrocatalytic methanol hydrogen production and the remaining methanol alkali solution are used as raw materials for preparing insurance powder, and the electrocatalytic methanol hydrogen production is coupled with the insurance powder production by regulating the raw material ratio and reaction process control of the electrocatalytic methanol hydrogen production, so that the hydrogen production waste liquid can be efficiently used for insurance powder production when the electrolyte is replaced at any reaction degree, and the electrocatalytic methanol hydrogen production is allowed to always maintain a high hydrogen production rate at a higher reactant concentration and a lower overpotential, and greatly reduce the waste of raw materials, thereby realizing efficient utilization of raw materials and obtaining high-purity hydrogen and high-value-added insurance powder. Specific implementation method:

[0019] The following is a further description of the present invention, but not a limitation of the present invention.

[0020] Example 1: A method for the safe online hydrogen production from electrocatalytic methanol coupled with the preparation of hydrosulfur powder comprises the following steps:

[0021] (1) 1000 L of a methanol-alkali solution containing 4 mol / L methanol and 4 mol / L sodium hydroxide was placed in a sealed electrolytic cell with a capacity of 1000 L. The overvoltage was automatically adjusted to maintain a hydrogen production rate of 4 kg / h, and the reaction degree of the electrocatalytic methanol-to-hydrogen reaction was monitored online in real time. When the reaction degree reached 50%, the hydrogen production reaction waste liquid was discharged at a rate of 125 L / h, and the methanol-alkali solution was replenished to the hydrogen production electrolytic cell at a rate of 125 L / h to maintain a dynamic equilibrium between the concentrations of reactants and products in the electrolytic cell. At this time, the overvoltage was 0.5 V.

[0022] (2) The hydrogen production reaction waste liquid described in step (1) is introduced into the synthesis reactor of the hydrosulfite production line, and sulfur dioxide is introduced into the synthesis reactor according to the volume of the hydrogen production reaction waste liquid and the concentration of each component, and stirred evenly. The pH is controlled to 4.4 by automatically adjusting the sulfur dioxide feed rate, the reaction temperature is controlled to 85°C by a steam heating device, and the pressure in the reactor is controlled to 0.15 MPa. After the addition is completed, the reaction is allowed to proceed for 60 minutes before discharging.

[0023] (3) Sulphite is obtained through precipitation, filtration, washing, and drying, with a synthetic conversion rate of 95%. The waste liquid from the production of sulphite is treated with methanol for recycling, and the obtained methanol is reused in electrocatalytic methanol hydrogen production or retained as a solvent for the production of sulphite, thus achieving material recycling.

[0024] Example 2

[0025] Referring to Example 1, the difference is that the dynamic equilibrium position in the electrolytic cell of the electrocatalytic methanol to hydrogen process is maintained differently, that is, the reaction degree of the electrocatalytic methanol to hydrogen reaction is different.

[0026] The process includes the following steps:

[0027] (1) 1000 L of a methanol-alkali solution containing 4 mol / L methanol and 4 mol / L sodium hydroxide was placed in a sealed electrolytic cell with a capacity of 1000 L. The overvoltage was automatically adjusted to maintain a hydrogen production rate of 4 kg / h, and the reaction degree of the electrocatalytic methanol-to-hydrogen reaction was monitored online in real time. When the reaction degree reached 70%, the hydrogen production reaction waste liquid was discharged at a rate of 125 L / h, and the methanol-alkali solution was replenished to the hydrogen production electrolytic cell at a rate of 125 L / h to maintain a dynamic equilibrium between the concentrations of reactants and products in the electrolytic cell. At this time, the overvoltage was 1 V.

[0028] (2) The hydrogen production reaction waste liquid described in step (1) is introduced into the synthesis reactor of the hydrosulfite production line, and sulfur dioxide is introduced into the synthesis reactor according to the volume of the hydrogen production reaction waste liquid and the concentration of each component, and stirred evenly. The pH is controlled to 4.4 by automatically adjusting the sulfur dioxide feed rate, the reaction temperature is controlled to 85°C by a steam heating device, and the pressure in the reactor is controlled to 0.15 MPa. After the addition is completed, the reaction is allowed to proceed for 60 minutes before discharging.

[0029] (3) Sulphite is obtained through precipitation, filtration, washing, and drying, with a synthetic conversion rate of 95%. The waste liquid from the production of sulphite is treated with methanol for recycling, and the obtained methanol is reused in electrocatalytic methanol hydrogen production or retained as a solvent for the production of sulphite, thus achieving material recycling.

[0030] Calculation Example 1:

[0031] Cost accounting is performed for a single hydrogen refueling station in Example 1 that produces 500 kg of hydrogen per day and uses an online electrocatalytic methanol safe online hydrogen production coupled with a hydrosulfite preparation process. Its theoretical annual output is 180 tons of hydrogen and 7,830 tons of hydrosulfite, with an annual consumption of 1,440 tons of methanol, 3,600 tons of sodium hydroxide, 5,760 tons of sulfur dioxide, and 3.7 million kWh of electricity. After applying the online electrocatalytic methanol safe online hydrogen production coupled with a hydrosulfite preparation process, compared to the case without process coupling, on the one hand, it can save raw materials and on the other hand, increase hydrogen production capacity. It is estimated that 5% to 15% of the use of raw materials such as methanol and sodium hydroxide can be saved each year, with a value of approximately 684,000 to 2,052,000 yuan. It is estimated that 10% to 20% of hydrogen production capacity can be increased each year, with a value of approximately 1.44 to 2.88 million yuan.

Claims

1. A method for the safe online production of hydrogen from methanol by electrocatalysis coupled with the preparation of hydrosulfite, characterized in that: A process for safely producing hydrogen online using methanol by coupling an electrocatalytic methanol process with a process for producing sodium formate-based sodium sulfate is provided. The method comprises the following steps: waste liquid containing sodium formate as a byproduct, residual methanol and sodium hydroxide produced by the electrocatalytic methanol process is directly used as a raw material for producing sodium formate-based sodium sulfate. The process flow of the co-production method comprises the following steps: (1) A methanol-alkali solution is placed in a sealed electrolytic cell, and a voltage is applied to the catalytic electrode for online hydrogen production; the concentrations of reactants and products in the process of electrocatalytic methanol hydrogen production are monitored online in real time. After the reaction reaches a certain level, the waste liquid of the hydrogen production reaction is drawn out, and the methanol-alkali solution is added to the hydrogen production electrolytic cell to maintain a dynamic balance of the concentrations of reactants and products in the electrolytic cell; the degree of electrocatalytic methanol hydrogen production reaction in the electrolytic cell is maintained at 20% to 80%; the methanol-alkali solution is a mixed solution of methanol and sodium hydroxide; (2) Introduce the waste liquid from the hydrogen production reaction into the synthesis reactor of the sodium hypochlorite production line, and according to the volume of the waste liquid from the hydrogen production reaction and the concentration of each component, introduce sulfur dioxide into the synthesis reactor and stir it evenly; control the pH by automatically adjusting the sulfur dioxide feed rate, control the reaction temperature by the heating device, and control the pressure in the reactor to be constant; after the addition is completed, maintain it for a period of time before discharging the material; (3) The hydrosulfite is obtained through the steps of precipitation, filtration, washing and drying, and the waste liquid obtained from the hydrosulfite production is treated with methanol. The obtained methanol is reused in the electrocatalytic methanol hydrogen production, or is continued to be used as a solvent for the hydrosulfite production, thereby realizing the recycling of materials.

2. The co-production method according to claim 1, characterized in that: In step (1), the methanol alkaline solution is a mixed solution of methanol and sodium hydroxide in a molar ratio of 0.2 to 2, and the amount thereof fed into the electrolytic cell is determined according to the size and capacity of a single cell of the electrolytic cell and the number of electrolytic cells; the catalytic electrode for electrocatalytic methanol to hydrogen production is a nickel electrode.

3. The co-production method according to claim 1, characterized in that: The electrolyte renewal rate is determined by the concentration of the methanol alkaline solution and the hydrogen production rate. By controlling the electrolyte renewal rate, the reactant concentration in the electrolytic cell is maintained constant at 0.8~3.2mol / L.

4. The co-production method according to claim 1, characterized in that: The main components of the waste liquid from the electrocatalytic methanol to hydrogen reaction are sodium formate, methanol and sodium hydroxide.

5. The co-production method according to claim 1, characterized in that: The temperature in the hydrosulfite synthesis reactor is maintained at 70~90℃, the pressure is maintained at 0.1~0.4Mpa, the pH is maintained at 4.3~4.5, and the reaction time is 40~100min.

6. The co-production method according to claim 1, characterized in that: The electrocatalytic methanol hydrogen production process and the sodium hypochlorite production process are either continuous, that is, the hydrogen production waste liquid is directly supplied to the sodium hypochlorite production line, or split, that is, the hydrogen production waste liquid is first stored and then transported to the sodium hypochlorite production line.