SCR NOx Patents: Top Companies & Filing Trends 2026
- Concentrated at the top. The five leading assignees hold 33.6% of all 13,767 records in scope, and the ranked leaders extend to 44.7% by the tenth position.
- Filings past their peak but not gone. Annual filings ran at 1,029 in 2017 and fell 34% from 528 in 2021 to 347 in 2024, the last year with a complete publication picture.
- Exhaust treatment and separation dominate the claim space. F01N and B01D classes each cover roughly half of all records, while engine control and fuel supply remain comparatively lightly claimed.
Filing growth compares 2021 (528 records) with 2024 (347) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 13,767 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
Selective catalytic reduction (SCR) converts nitrogen oxides in engine and combustion exhaust into nitrogen and water using a reductant, typically ammonia or urea, over a catalyst bed. The patent record in scope spans 13,767 published documents filed or published between 2015 and mid-2026, drawn from filings that reference core SCR mechanics — vanadia-titania chemistry, ammonia slip control, catalyst deactivation and regeneration, sulphur trioxide interference, and the catalyst’s operating temperature window. These are the recurring technical fault lines that separate one claim set from another.
The dataset sits mostly in mobile and stationary emissions control: diesel and gasoline vehicle aftertreatment, off-road equipment, and industrial flue-gas denitrification. Because SCR is a mature, heavily instrumented field, most of the activity below concerns incremental catalyst formulation, dosing control, and system integration rather than the base reaction chemistry itself.
Filing trends and technology composition
Two views of the same 13,767-record set: how filing activity has moved year over year, and how records distribute across IPC subclasses.
Filing trend, 2017–2026
Filings peaked at 1,029 in 2017 and had declined to 40 by the most recent partial year. Because publication lags filing by roughly 18 months, the 2025-2026 figures are still filling in and should not be read as a continued slide; the more reliable comparison is 2021 (528) against 2024 (347), a 34% fall over that three-year span.
Technology composition by IPC subclass
F01N (exhaust silencers & treatment) and B01D (separation processes) each appear in roughly half of all records — 52.8% and 50.1% respectively — reflecting how tightly SCR claims are bound to physical aftertreatment hardware. B01J (catalysis) follows at 38.2%. Engine control (F02D, 6.9%), inorganic chemistry (C01B, 5.5%) and fuel supply (F02M, 2.5%) are present but far less densely claimed, since a record can carry multiple classes these shares sum to more than 100%.
Shares are the percentage of the 13,767 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Selective Catalytic Reduction of Nitrogen Oxides with Eureka
This page is one run against one query. Ask Eureka your own question about selective catalytic reduction of nitrogen oxides and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative filing and most-cited prior art
Method for managing ammonia slip (US20120285143A1)
An internal combustion engine configured for compression-ignition combustion includes an exhaust aftertreatment system with an ammonia-selective catalytic reduction device. The method determines the engine's NOx generation rate, the device's NOx reduction rate, and the resulting ammonia slip rate, then adjusts engine operation in response.Filed by GM Global Technology Operations LLC, published 2012-11-15.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | WO2011080525A1 | Method of coating a monolith substrate with catalyst component | 413 |
| 2 | WO2008106519A1 | Copper CHA zeolite catalysts | 411 |
| 3 | US20090193796A1 | Gasoline engine emissions treatment systems having particulate traps | 344 |
| 4 | US20080045405A1 | Pt-Pd diesel oxidation catalyst with CO/HC light-off and HC storage function | 334 |
| 5 | US5628186A | Method and apparatus for controlled introduction of a reducing agent into a nitrogen oxide-containing exhaust… | 334 |
| 6 | WO1999039809A1 | SYSTEM FOR NOx REDUCTION IN EXHAUST GASES | 321 |
| 7 | US6125629A | Staged reductant injection for improved NOx reduction | 320 |
| 8 | US6314722B1 | Method and apparatus for emission control | 293 |
| 9 | US7601662B2 | Copper CHA zeolite catalysts | 292 |
| 10 | US6415602B1 | Control system for mobile NOx SCR applications | 288 |
Citation counts favour older records simply because they have had longer to accumulate citations inside the corpus — treat them as a signal of influence on later filings, not as a marker of present-day importance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Three read-throughs from the filing and citation data that matter for where to file and who to watch.
Ownership is concentrated but not closed
The five leading assignees together hold 33.6% of all records in scope, rising to 44.7% across the top ten. That leaves more than half the field split among a long tail of single- and few-filing entrants — room to build a position without immediately colliding with a dominant portfolio.
Activity has cooled from its 2017 peak
Filings ran at 1,029 in 2017, the peak year, and fell 34% from 528 in 2021 to 347 in 2024 — the last year with a reasonably complete publication picture. This looks more like a maturing field consolidating around known catalyst chemistries than one still expanding its claim frontier.
Hardware integration outweighs base chemistry
The heaviest claim density sits in exhaust treatment hardware (F01N) and separation processes (B01D), each near or above half of all records. Base catalytic chemistry (B01J) and inorganic compound claims (C01B) are present at lower density, suggesting more open ground in reductant chemistry than in system integration.
Filing strategy still centres on the US and Europe
The United States receives the largest single share of filings, followed by the EPO and WIPO's PCT route, with the UK, India and China each carrying a meaningful but smaller share. A defensive filing strategy built only around the largest offices will miss activity building in India and China.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to selective catalytic reduction of nitrogen oxides, with the prior art for and against each one.
Who is filing, and where momentum is shifting
The leading assignees combine automotive OEMs, catalyst specialists and emissions-system suppliers, but recent-year momentum diverges sharply between them.
Catalyst makers file jointly with their own subsidiaries
The strongest co-assignee pairs in this dataset link a parent company with its own regional or subsidiary entity, rather than two independent companies collaborating. That pattern points to internal IP consolidation across group structures more than open cross-industry partnership.
Momentum has slowed even among frequent filers
Two of the more active filers each show only a handful of filings in the latest year, down sharply year-on-year. Given the 18-month publication lag, part of this is measurement artefact rather than a real halt — but it is consistent with the broader 2021-2024 decline.
A few smaller filers are still growing, from a low base
At least one mid-ranked assignee posted year-on-year growth in its latest-year filing count, though off a small absolute number. That is a reminder that portfolio momentum in a maturing field is uneven — some specialists are still building position even as the field average cools.
| Assignee | Recent year | YoY |
|---|---|---|
| Johnson Matthey PLC | 6 | -84% |
| Cummins Inc | 6 | -73% |
| Umicore AG & Co KG | 2 | +100% |
| Scania CV AB | 1 | 0% |
| BASF Corporation | 0 | -100% |
| Cummins Emission Solutions Inc | 0 | -100% |
| Ford Global Technologies LLC | 0 | — |
| General Electric Company | 0 | — |
Where to take this analysis
The dataset points to specific next steps depending on whether the goal is freedom-to-operate, portfolio building, or competitive tracking.
Check freedom-to-operate against the leading claim clusters
With 44.7% of records held by the top ten assignees, a freedom-to-operate review should start with those portfolios' claims around exhaust hardware and catalyst formulation before assuming open ground.
Run a claim clearance search in EurekaTrack momentum shifts, not just headline share
Year-on-year filing counts diverge sharply between the leading assignees, some pulling back sharply and others still growing from a smaller base. Monitoring these shifts flags who is actually active now.
Set up assignee monitoring in EurekaScope the under-claimed branches before committing R&D
Ammonia slip catalyst placement and low-temperature-window formulations show thinner filing density than core hardware classes, which may indicate room for a defensible first claim.
Explore white space in EurekaFrequently asked questions
Filing activity in this field is concentrated among a small group of automotive OEMs and catalyst specialists, with the leading assignee alone accounting for a substantial share of the 13,767 records in scope. The top five assignees together hold 33.6% of all records, and that share extends to 44.7% across the top ten. Beyond that point ownership spreads across a long tail of smaller filers, so the field is concentrated at the top but not closed to new entrants.
Filings peaked in 2017 at 1,029 and have declined since, with a 34% drop from 528 filings in 2021 to 347 in 2024, the most recent year with a reasonably complete publication record. Because publication lags filing by roughly 18 months, the 2025-2026 figures shown in raw form understate real activity and should not be read as evidence the field has stopped moving. The more defensible reading is that filing has cooled from its 2017 high rather than continuing to expand.
Ammonia slip control and catalyst deactivation claims sit mainly within F01N (exhaust treatment hardware, 52.8% of records) and B01J (catalysis, 38.2% of records), often alongside B01D (separation processes, 50.1%). Because a single record commonly carries several IPC codes, these figures overlap rather than sum to a total. Engine control claims (F02D) touch ammonia slip management from the control-systems side but appear in a smaller 6.9% of records, making that intersection comparatively less crowded.
The heaviest claim density sits in exhaust hardware integration and separation processes, both near or above half of all records, while base catalyst chemistry and inorganic compound formulations carry proportionally lighter claim coverage. Specific under-claimed branches include ammonia slip catalyst placement strategies, low-temperature-window vanadia-free formulations, and onboard catalyst regeneration diagnostics. Any of these merits a dedicated freedom-to-operate check before committing R&D, since thinner filing density does not guarantee the space is genuinely open.
The United States receives the largest volume of filings among the receiving offices tracked, at 4,137, followed by the European Patent Office at 2,220 and the WIPO PCT route at 1,399. The United Kingdom, India and China follow with meaningfully smaller but still notable volumes. A filing or clearance strategy built solely around the US and Europe would miss real activity building in India and China.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.