Sulfuric Acid Electrolysis Temperature and Flow Control
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Solution Overview
Problem
Conventional sulfuric acid electrolysis processes using conductive diamond anodes face challenges with high viscosity and coagulation point variations, leading to electrolytic operation failures at concentrations above 70% by mass and current densities above 20 A/dm2, resulting in increased cell voltage and reduced current efficiency due to gas liberation and precipitation issues.
Innovation Solution
The process involves separating the anode and cathode compartments with a diaphragm, controlling the electrolyte temperature to 30°C or more and adjusting the flow rates of the electrolyte to be at least 1.5 times the calculated flow rates of gas generated, ensuring stable operation by preventing gas and product accumulation on the electrode surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If concentrated sulfuric acid (above 70% by mass) is used as electrolyte to increase persulfuric acid production efficiency, then current efficiency is improved, but cell voltage increases and electrolytic operation fails due to gas liberation and precipitation issues
Solution Approach 1:
The patent changes the temperature parameter from ambient to 30°C or more, which fundamentally alters the physical properties of concentrated sulfuric acid. This temperature increase reduces viscosity, enhances gas solubility, and prevents precipitation, thereby enabling stable electrolytic operation at high concentrations (70-98% by mass) without cell voltage failure
Solution Approach 2:
The patent performs preliminary heating of the concentrated sulfuric acid electrolyte to 30°C or more before electrolysis begins. This preliminary action prevents gas accumulation and precipitation issues from occurring during electrolysis, ensuring continuous stable operation at high current densities (above 20 A/dm²) and concentrations (above 70% by mass)
2Productivity
If concentrated sulfuric acid is used as electrolyte to achieve high wash stripping efficiency, then cleaning performance is improved, but gas from electrolysis is hard to liberate and bubbles take time to diffuse, increasing cell voltage
Solution Approach 1:
By increasing the temperature parameter to 30°C or more, the patent fundamentally changes the solubility and diffusion characteristics of gas in concentrated sulfuric acid. This enables rapid gas diffusion and liberation even at high concentrations (90-98% by mass), preventing bubble accumulation on electrode surfaces while maintaining high wash stripping efficiency
3Stability of the object's composition
If concentrated sulfuric acid is used as electrolyte to produce stable oxidizing agent, then persulfuric acid stability is improved, but other substances precipitate due to low solubility, interfering with electrolytic current flow
Solution Approach 1:
The patent changes the temperature parameter to 30°C or more, which fundamentally improves the solubility of substances in concentrated sulfuric acid. This prevents precipitation of other substances even at high concentrations (70-98% by mass), ensuring clear electrolyte and continuous electrolytic current flow while maintaining oxidizing agent 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
This approach stabilizes the electrolysis process by maintaining low cell voltage and preventing electrolytic current failures, enhancing the production of persulfuric acid with high wash stripping efficiency for photoresist removal while minimizing decomposition and Joule heat effects.
Implementation Method 1
directly electrolyzes concentrated sulfuric acid by using the conductive diamond anode to form oxidizing agent stably
Implementation Method 2
electrolysis reaction of concentrated Sulfuric acid, such as peroxomonosulfuric acid
Implementation Method 3
the anode compartment is separated from the cathode compartment by a diaphragm
Implementation Method 4
the temperature of said electrolyte containing sulfuric acid to be supplied to said anode compartment and said cathode compartment is controlled to 30 degree Celsius or more
Implementation Method 5
the flow rate F1 (L/min.) of said electrolyte containing sulfuric acid to be supplied to said anode compartment is controlled to 1.5 times or more (F1/Fa≧1.5) the flow rate Fa (L/m in.) of gas formed on the anode side
Data Source
AI summary
Sulfuric acid electrolysis process wherein;a temperature of electrolyte containing sulfuric acid to be supplied to an anode compartment and a cathode compartment is controlled to 30 degree Celsius or more;a flow rate F1 (L/min.) of the electrolyte containing sulfuric acid to be supplied to said anode compartment is controlled to 1.5 times or more (F1/Fa≧1.5) a flow rate Fa (L/min.) of gas formed on an anode side as calculated from Equation (1) shown below and a flow rate F2(L/min.) of said electrolyte containing sulfuric acid to be supplied to said cathode compartment is controlled to 1.5 times or more (F2/Fc≧1.5) a flow rate Fe (L/min.) of gas formed on a cathode side as calculated from Equation (2) shown below.Fa=(I×S×R×T)/(4×Faraday constant) Equation (1)Fe=(I×S×R×T)/(2×Faraday constant) Equation (2)I: Electrolytic current (A)S: Time: 60 second (Fixed)R: Gas constant (0.082 1·atm/K/mol)K: Absolute temperature (273.15 degree Celsius+T degree Celsius)T: Electrolysis temperature (degree Celsius)Faraday constant: (C/mol)