Method for producing boron hydrides by electrolysis

A technology of borohydride and metaborate, applied in the electrolysis process, electrolysis components, etc., can solve the problems of losing the significance of hydrogen storage materials, high price of borohydride, and inability to recycle boron, so as to improve the electrochemical reaction rate and current efficiency, improving mass transfer conditions, and saving energy

Inactive Publication Date: 2007-11-14
NANJING UNIV OF TECH
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  • Summary
  • Abstract
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AI Technical Summary

Problems solved by technology

It can be seen that it is imminent to develop the recycling technology of boron resources. On the other hand, as a hydrogen storage material, if the hydrogen storage cycle after dehydrogenation cannot be realized, it will lose its significance as a hydrogen storage material.
[0004] At present, the production of sodium borohydride mainly adopts the Schlesinger method and the Bayer method, etc., but these methods have the disadvantages of high cost, large pollution, and harsh reaction conditions.
None of these methods use metaborate as a raw material, and cannot directly realize the recycling of boron.
Cooper (US3437842), Hale (US4931154) reported that electrolytic method prepares sodium borohydride, but reaction rate is slow, and electric current efficiency is low (<25%), Chinese patent CN1284112A and CN1396307A also report electrolytic method and prepare sodium borohydride, all adopt price Expensive cation exchange membrane (such as Nafion membrane) separates the cathode and anode compartments
However, the problem that the price of borohydride is too high at present is that it is a bottleneck as a hydrogen source, which limits its application.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] Porous SiO 2 The ceramic membrane separates the cathode and anode chambers, with copper as the cathode, nickel as the anode, and the cathode chamber solution as LiOH and LiBO 2 A mixed solution in which LiOH concentration 1.0M, LiBO 2 is the saturation concentration. The cathodic compartment solution is the same as the cathodic compartment. The pressure difference between the anode chamber and the cathode chamber is controlled to be 300Pa, the cell voltage is 2.9V, and the cathode electrode potential is controlled at 1.3-1.8V (relative to the saturated calomel electrode). The electrolysis is terminated when the concentration of sodium borohydride reaches more than 30%.

Embodiment 2

[0020] A porous stainless steel membrane is used to separate the cathode and anode compartments, with Cu as the cathode, Pb as the anode, and the solution in the anode compartment as KOH and KBO 2 The mixed solution, in which KOH concentration is 2.0M, KBO 2 is the saturation concentration, the cathode compartment is the same as the anode. The pressure difference between the anode chamber and the cathode chamber is controlled to be 150Pa, the voltage is 2.8V, and the potential of the cathode electrode is controlled at 1.3-1.8V (relative to the saturated calomel electrode). The electrolysis is terminated when the concentration of sodium borohydride reaches more than 30%.

Embodiment 3

[0022] Porous Al 2 o 3 The ceramic membrane separates the cathode chamber and the anode chamber. The sponge granular Ti metal is used as the cathode, and the anode is loaded with 0.1-5% Ta on the surface. 2 o 5 -RuO 2 -IrO 2 Ni metal particles; Ta rods are used as current collecting anodes, Ti rods are current collecting cathodes; the cathode chamber solution is NaOH and NaBO with 2% to 20% (volume ratio) isopropylamine added 2 Mixed solution, NaOH concentration is 1.0M, NaBO 2 The concentration is 2.0M, and the anode chamber uses the same concentration of NaOH and NaBO as the cathode chamber 2 Solution; the pressure difference between the anode chamber and the cathode chamber is controlled to be 500-1000Pa, the voltage is 3.1V, and the potential of the cathode electrode is controlled at 1.3-1.8V (relative to the saturated calomel electrode). The pulse period is 0.02 seconds, the duty cycle is 50%, and the electrolysis is terminated when the borohydride concentration rea...

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PUM

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Abstract

The invention relates to a method of electrolyzing production borohydride. Electrolyser adopts blown film as the barrier film. The mixed liquor of metaborate and alkali is loaded in anode chamber and cathode chamber. Organic amine solution exists in cathode chamber. The material of anode or cathode is the granular material of slaty or fluidized bed. The pressure of anode chamber solution should be higher than that of cathode chamber solution at the time of electrolysis. The pressure difference is above 100Pa, so that it can prevent the BH4- of cathode chamber moving to the anode chamber. The mosaic electrode can largely enhance the surface area of electrode, improve the condition of mass transfer, and enhance the speed of electrochemical reaction. Pulse electrolytic technology is adopted to improve the electrochemical reaction speed and the current efficiency, which realizes metaborate directly regenerating to borohydride. It provides a more inexpensive source of hydrogen material for hydrogen supply system, and it also largely reduces the operating cost.

Description

technical field [0001] The present invention relates to a production method of borohydride mainly used for storing hydrogen and providing hydrogen source, especially a method for producing borohydride by electrolysis. Background technique [0002] Hydrogen energy is the most ideal secondary energy source. The development and utilization of hydrogen energy is how to realize the cheap production of hydrogen and the safe storage of hydrogen. The International Energy Agency pointed out that a practical hydrogen storage system must reach 5% (mass fraction) and 62kg / m 3 (volume hydrogen storage capacity) indicator. Sodium borohydride is used as a hydrogen storage material. In current practical applications, its hydrogen storage efficiency mass fraction is 7.4%, and its volume hydrogen storage capacity is 78kg / m 3 , can be further improved, and at the same time has the advantage of not needing high voltage and can be directly used for instant hydrogen supply of fuel cells, suitab...

Claims

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Application Information

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IPC IPC(8): C25B1/00
Inventor 周幸福范益群
Owner NANJING UNIV OF TECH
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