High-Temperature Alkaline Electrolysis with Liquid-Phase KOH
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing water electrolysis technologies face limitations in operating at high temperatures without damaging polymeric membranes and require expensive materials and external heating for high-temperature solid oxide electrolysers.
Innovation Solution
A method for high temperature and pressure alkaline electrolysis (AWE-HTP) using multilayer electrodes with a hydrophobic layer to control aqueous alkaline solution flow, maintaining the solution in a liquid state and optimizing temperature and pressure conditions for efficient electrolysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polymeric membranes are used in alkaline water electrolysis, then the system can operate at low cost with simple structure, but the membranes are irreversibly damaged when operating temperature exceeds 150°C
Solution Approach 1:
The invention changes the operating parameters by using a concentrated alkaline electrolyte solution (30-85% KOH or NaOH) at temperatures between 150°C and 374°C and pressures above 2.2 bar. This parameter change allows the system to operate above the traditional polymeric membrane temperature limit while maintaining liquid electrolyte phase, thereby resolving the contradiction between ease of manufacture and operating temperature.
2Temperature
If solid oxide electrolysers are used for high temperature electrolysis, then the system can operate at temperatures above 500°C, but expensive ceramic materials are required
Solution Approach 1:
The invention operates at intermediate temperatures (150°C to 374°C) using concentrated alkaline electrolyte, which is lower than solid oxide electrolyser temperatures (500-1000°C) but higher than traditional alkaline electrolysis. This temperature parameter change allows the use of simpler, less expensive materials while still achieving high-temperature electrolysis benefits, resolving the contradiction between operating temperature and material cost.
3Temperature
If water is fed in gaseous state to high temperature electrolysis, then the electrolysis reaction can proceed at high temperature, but external energy is required for heating
Solution Approach 1:
The invention utilizes phase transition by maintaining water in liquid phase through high pressure (above 2.2 bar) while operating at elevated temperatures (150°C to 374°C). The concentrated alkaline electrolyte solution remains liquid under these conditions, eliminating the need for external heating to vaporize water, thus resolving the contradiction between electrolysis temperature and external heating energy requirements.
4Loss of energy
If temperature is increased to improve voltage efficiency, then the electrolysis efficiency increases, but the electrolyte may vaporize at high temperatures
Solution Approach 1:
The invention changes the electrolyte composition to concentrated alkaline solutions (30-85% KOH or NaOH), which have higher boiling points than pure water. This composition change allows the system to operate at temperatures up to 374°C while maintaining liquid phase stability, resolving the contradiction between voltage efficiency improvement through temperature increase and electrolyte phase stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Achieves high voltage efficiency and stable operation at temperatures above 150°C with pressures between 2.2 and 129.1 bar, overcoming membrane damage and material costs, with efficiencies greater than 100%.
Implementation Method 1
a hydrophobic layer (3) facing towards said channel (2)
Implementation Method 2
a catalyst layer (5) configured to catalyse a reduction phase of said hydrogen or an oxidation phase of said oxygen
Implementation Method 3
a porous electrode layer (4) configured to allow said reduction or said oxidation to take place
Implementation Method 4
The apparatus that allows the dissociation of water into hydrogen and oxygen under the effect of an electric current is an electrochemical reactor called water electrolyser
Implementation Method 5
a heat exchanger for heating the aqueous solution
Implementation Method 6
the pressure is greater than the minimum for maintaining the liquid state of the electrolyte
Data Source
Figure 1a~1b
Figure 2~3
Figure 4~5
AI summary
The present invention relates to a method for electrolysis of water (1 ) by means of a device (7) comprising a reversible cell for the production of hydrogen and oxygen. A solution of potassium hydroxide (KOH) is fed into the cell at a concentration of between 35% and 55% w/v, at a temperature of between 150°C and 374°C, and in a condition of minimum pressure of between 2.2 bar and 129.1 bar. The method provides for I) preparing in the mixer the aqueous alkaline solution of KOH having a concentration of potassium hydroxide (KOH) of between 35% and 55% w/v; II) heating said aqueous alkaline solution to a temperature of between 150°C and 374°C; III) increasing the pressure to maintain the aqueous alkaline solution in the liquid phase at a minimum pressure condition of between 2.2 bar and 129.1 bar; IV) passing the water through the hydrophobic layer (3) of each electrode and reaching the respective catalyst layer (5) to catalyse a reduction phase of said hydrogen or an oxidation phase of said oxygen and the porous electrode layer (4) to carry out said reduction and said oxidation respectively; V) collecting gaseous hydrogen and oxygen released from phase IV).