Making Caustic Soda with Less Salt Using a Special Electrolysis Cell
This patent describes a method to make purer caustic soda and chlorine gas using a two-chamber electrolysis cell with a gas diffusion electrode by carefully controlling pressure differences.
Original patent title: “Method of electrolysis employing two-chamber ion exchange membrane electrolytic cell having gas diffusion electrode”
This patent describes a method to make purer caustic soda and chlorine gas using a two-chamber electrolysis cell with a gas diffusion electrode by carefully controlling pressure differences. Granted to Chlorine Engineers Corp in 2015 with 9 claims and 7 forward citations, and it is expected to expire in 2030.
Coverage
What does this patent actually cover?
The patent claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more → a method for electrolyzing brine (saltwater) in a "two-chamber ion exchange membrane electrolytic cell" (ClaimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 1). This cell has an "anode chamber" and a "cathode gas chamber" separated by an "ion exchange membrane." The cathode chamber uses a "gas diffusion electrode." The core idea is "reducing a differential pressure" between the liquid pressure in the anode chamber and the gas pressure in the cathode gas chamber (Claim 1). This pressure difference is precisely controlled, for example, reduced to "2.4 kPa or less" (Claim 1) or "-21.6 kPa or more" (Claim 2), by adjusting a "sealing pot or a valve" (Claim 1). This precise pressure control helps in "decreasing a salt concentration in the caustic soda aqueous solution" (Claim 1). For example, by carefully adjusting the valve downstream of the cathode chamber, the pressure inside the cathode chamber can be increased, which reduces the pressure difference across the membrane, leading to purer caustic soda.
The gap
What does this patent NOT cover?
- Electrolysis methods that do not use a "two-chamber ion exchange membrane electrolytic cell."
- Electrolysis cells that do not employ a "gas diffusion electrode" as the cathode.
- Methods that do not involve reducing the differential pressure between the anode liquid and cathode gas.
- Methods where the differential pressure is not controlled to be "2.4 kPa or less" or "-21.6 kPa or more."
- Electrolysis processes for producing chemicals other than chlorine gas and caustic soda.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
The noveltynoveltyThe requirement that an invention be different from anything publicly known before its priority date.Read more → lies in precisely managing the pressure difference across the ion exchange membrane in a two-chamber cell with a gas diffusion electrode. By reducing this "differential pressure" to specific narrow ranges (e.g., 2.4 kPa or less), the method significantly lowers the unwanted salt concentration in the produced caustic soda solution.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Chlor-alkali plants
Manufacturing of PVC (polyvinyl chloride)
Water treatment facilities
Pulp and paper production
Textile bleaching
Why it matters
The bigger picture
Caustic soda (sodium hydroxide) and chlorine gas are fundamental chemicals used in countless industries, from making paper and plastics to purifying water. Producing these chemicals with lower salt impurities, as described in this patent, means the final products are cleaner and more valuable. This improved purity can reduce downstream processing costs and enhance the quality of products made using these chemicals.
Filed
April 15, 2010
Granted
November 10, 2015
Market context
Who's building on this
Companies in this space
Chlorine Engineers Corp Ltd, the original assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →, is a key player in chlor-alkali technology. Other major companies in the chlor-alkali industry, such as Asahi Kasei, thyssenkrupp Uhde Chlorine Engineers, and Covestro, continuously work on improving electrolysis cell efficiency and product purity.
Market impact
This patent contributes to the ongoing drive for higher efficiency and purity in the chlor-alkali industry. By enabling the production of caustic soda with lower salt content, it supports the creation of higher-grade chemicals, which can command better prices and reduce the need for further purification steps. This improvement helps maintain competitiveness and meet stringent quality standards in various downstream industries.
Claim 1 — Plain English
What this patent covers
The patent claims a method for electrolyzing brine (saltwater) in a "two-chamber ion exchange membrane electrolytic cell" (Claim 1). This cell has an "anode chamber" and a "cathode gas chamber" separated by an "ion exchange membrane." The cathode chamber uses a "gas diffusion electrode." The core idea is "reducing a differential pressure" between the liquid pressure in the anode chamber and the gas pressure in the cathode gas chamber (Claim 1). This pressure difference is precisely controlled, for example, reduced to "2.4 kPa or less" (Claim 1) or "-21.6 kPa or more" (Claim 2), by adjusting a "sealing pot or a valve" (Claim 1). This precise pressure control helps in "decreasing a salt concentration in the caustic soda aqueous solution" (Claim 1). For example, by carefully adjusting the valve downstream of the cathode chamber, the pressure inside the cathode chamber can be increased, which reduces the pressure difference across the membrane, leading to purer caustic soda.
The clever bit
The novelty lies in precisely managing the pressure difference across the ion exchange membrane in a two-chamber cell with a gas diffusion electrode. By reducing this "differential pressure" to specific narrow ranges (e.g., 2.4 kPa or less), the method significantly lowers the unwanted salt concentration in the produced caustic soda solution.
What it does not cover
- Electrolysis methods that do not use a "two-chamber ion exchange membrane electrolytic cell."
- Electrolysis cells that do not employ a "gas diffusion electrode" as the cathode.
- Methods that do not involve reducing the differential pressure between the anode liquid and cathode gas.
- Methods where the differential pressure is not controlled to be "2.4 kPa or less" or "-21.6 kPa or more."
- Electrolysis processes for producing chemicals other than chlorine gas and caustic soda.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
Patent enters public domain
PatentBrief Score
Impact Score
Early stage
Citation count
18/40
Early citations
Claim breadth
6/20
Moderate scope
Recency
5/20
Granted 10–20 years ago
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$101K – $323K
Midpoint $202K · 3.7 yr remaining · industry ×2.4
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Claim text not yet imported for this patent
The original legal language
Original claims
9 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Sugiyama, M., Asaumi, K., & Iguchi, Y. (2015). Making Caustic Soda with Less Salt Using a Special Electrolysis Cell (U.S. Patent No. 9,181,624). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/9181624/method-of-electrolysis-employing-two-chamber-ion-exchange-membrane-electrolytic-
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does Making Caustic Soda with Less Salt Using a Special Electrolysis Cell cover?
This patent describes a method to make purer caustic soda and chlorine gas using a two-chamber electrolysis cell with a gas diffusion electrode by carefully controlling pressure differences.
Who owns patent US 9181624?
Chlorine Engineers Corp owns this patent, granted in 2015.
When does this patent expire?
This patent is expected to expire on April 15, 2030, when the invention enters the public domain.
What is patent US 9181624 cited by?
This patent has been cited by 7 later patents that build on its ideas.
What problem does this patent solve?
Caustic soda (sodium hydroxide) and chlorine gas are fundamental chemicals used in countless industries, from making paper and plastics to purifying water. Producing these chemicals with lower salt impurities, as described in this patent, means the final products are cleaner and more valuable. This improved purity can reduce downstream processing costs and enhance the quality of products made using these chemicals.
What does this patent NOT cover?
Electrolysis methods that do not use a "two-chamber ion exchange membrane electrolytic cell."
Patent monitoring