SCR NOx Patents: Top Companies, Trends & White Space 2026
- 42.6% of all 1,027 records sit with just five assignees, so most of the core SCR-by-CO claim space is already staked by a small group of catalyst majors.
- Filings peaked in 2018 at 62 and have declined since, with the 2022 midpoint at 26 — this is a maturing field, not a growing one.
- B01D and B01J dominate at 68.6% and 64.2% of records respectively, while engine-control (F02D, 5.9%) and combustion-residue (F23J, 1.1%) angles remain comparatively thin.
What this landscape covers
Selective catalytic reduction using CO as a reductant sits at the intersection of exhaust after-treatment and catalytic chemistry: claims here typically address oxygen tolerance, sulfur poisoning resistance, low-temperature activity and sintering resistance in the catalyst formulation or system architecture. The dataset spans 1,027 published records filed or published between 2015 and mid-2026, drawn from a search anchored on SCR and CO-SCR terminology cross-referenced against these specific failure-mode and durability concepts.
Filing offices skew heavily toward the United States, Europe and the WIPO PCT route, with China, the United Kingdom and India each contributing a meaningful but smaller share — consistent with a technology whose commercial stakes are concentrated in on-road and stationary emissions compliance in mature regulatory markets.
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Filing trend and technology composition
Two views of the same 1,027 records: how filing activity has moved year over year, and which IPC subclasses carry the claims.
A field past its filing peak
Annual filings rose to a peak of 62 in 2018, held near that level briefly, then declined toward the 2022 midpoint of 26 and continued lower. The most recent year (2026) shows only 2 records, but publication lags filing by roughly 18 months, so recent years are understated in any raw count — the decline visible through 2022-2024 is the more reliable signal.
Concentrated in filtration and catalysis, thin in engine control
B01D (separation processes) and B01J (chemical/physical catalytic processes) each appear on well over half of all records, reflecting that most claims describe the catalyst article or filter system itself. F01N (exhaust treatment hardware) is also heavily represented. Engine-control integration (F02D) and combustion-residue handling (F23J) appear far less often, marking them as comparatively under-claimed system-level angles rather than core catalyst chemistry.
Shares are the percentage of the 1,027 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 NOx by CO with Eureka
This page is one run against one query. Ask Eureka your own question about selective catalytic reduction of nox by co and every answer comes back with the patent numbers behind it.
Try EurekaThe most-cited records in this space
Deterioration diagnosis apparatus for selective catalytic reduction catalyst (US20170167352A1)
Filed by Toyota, this record describes a diagnosis method that deliberately shifts the air-fuel ratio from lean to a predetermined rich condition to induce a water gas shift reaction in a pre-stage catalyst, then reads the resulting output difference between two air-fuel-ratio sensors to detect SCR catalyst deterioration.The claims center on a diagnostic control sequence rather than a catalyst composition, which narrows what it actually blocks for formulation-focused filers.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US4961917A | Method for reduction of nitrogen oxides with ammonia using promoted zeolite catalysts | 768 |
| 2 | US7229597B2 | Catalyzed SCR filter and emission treatment system | 317 |
| 3 | WO2005016497A1 | Emission treatment system and method using a SCR filter | 313 |
| 4 | US20050031514A1 | Catalyzed SCR filter and emission treatment system | 297 |
| 5 | WO2004076829A1 | Exhaust-gas purification system for the selective catalytic reduction of nitrogen oxides in the lean exhaust … | 233 |
| 6 | US20050069476A1 | Selective catalytic reduction | 233 |
| 7 | US7264785B2 | Selective catalytic reduction | 192 |
| 8 | US7093427B2 | Exhaust gas aftertreatment systems | 139 |
| 9 | US20040098974A1 | Exhaust gas aftertreatment systems | 123 |
| 10 | US20070089403A1 | Exhaust-gas purification system for the selective catalytic reduction of nitrogen oxides in the lean exhaust … | 114 |
Ranked by citation count within the searched corpus. Older records accumulate more citations simply by being available longer, so treat this as a signal of influence on the field's foundational chemistry, not of current commercial relevance.
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Browse MCP servers →What the numbers mean for strategy
Three patterns stand out once the concentration, trend and technology-class figures are read together.
The core chemistry is already claimed by a small group
With 438 of 1,027 records held across five assignees, and 57.9% (595 records) held across ten, new entrants working on core catalyst formulations for oxygen tolerance or sulfur resistance are filing into dense prior art held by a handful of established catalyst majors.
Filing activity has been declining since 2018
The 2022 midpoint of 26 filings, roughly half the 2018 peak, confirms this is not a temporary dip. Recency understatement from the 18-month publication lag does not change the multi-year downward trajectory visible from 2018 through the midpoint.
System integration claims are thin next to catalyst-article claims
Claims tied to engine control strategy (F02D) or combustion residue handling (F23J) each sit under 6% of records, far below the separation-process and catalysis classes. This gap suggests control-logic and residue-management approaches to CO-SCR performance are less crowded than the underlying catalyst chemistry.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to selective catalytic reduction of nox by co, with the prior art for and against each one.
Who holds the ground, and where it is still open
The ranked leaders account for a majority of filings, but the concentration is front-loaded: the gap between the leader (195 records) and fifth place (41) is far larger than the gap from fifth to tenth (23).
One filer holds nearly five times the fifth-place total
The leading assignee's 195 records dwarf the fifth-place holding of 41, indicating a single catalyst major set much of the early claim baseline that later entrants have had to file around.
A tight cluster forms below the top five
The step from fifth (41) to tenth (23) is comparatively gradual next to the drop from leader to fifth, pointing to a cluster of catalyst and automotive suppliers contesting adjacent claim territory rather than one runaway leader across the board.
Even top assignees have gone quiet recently
Recent-year momentum figures show the leading assignees recording zero or near-zero filings in the latest tracked year, including one leader down 100% year-on-year. This is consistent with the broader decline from the 2018 peak rather than a single company retreating.
| Assignee | Recent year | YoY |
|---|---|---|
| Umicore AG & Co. KG | 1 | — |
| Johnson Matthey PLC | 0 | -100% |
| BASF Corporation | 0 | — |
| Engelhard Corporation | 0 | — |
| Johnson Matthey Catalysts (Germany) GmbH | 0 | — |
| Tronox LLC | 0 | — |
| BASF Catalysts LLC | 0 | — |
| Treibacher Industrie AG | 0 | -100% |
Where to take this analysis
The dataset points to specific next steps depending on whether the goal is freedom-to-operate, licensing, or R&D targeting.
Run a freedom-to-operate check against the top five
Given that 42.6% of all records sit with five assignees, any new catalyst-composition filing should be checked against their specific claim scope before drafting, not just against the field in general.
Start an FTO scan in EurekaProbe the under-claimed system-integration branches
Engine-control and combustion-residue angles show materially lower claim density than the core catalyst chemistry, making them a plausible place to stake new ground with a system-level claim.
Explore white space in EurekaTrack whether the filing decline reflects consolidation or shift
The drop from a 2018 peak of 62 to a 2022 midpoint of 26 could reflect market maturity, IP strategy consolidation among leaders, or R&D redirection toward adjacent NOx-reduction chemistries — each implies a different response.
Monitor assignee activity in EurekaCommon questions about SCR-by-CO patenting
The ranked leader in this dataset holds 195 of the 1,027 records in scope, a much larger share than the fifth-place holder's 41. That gap indicates one catalyst major established a broad early baseline of claims that later filers, clustered more tightly between fifth and tenth place with 23 records, have had to design around. This concentration pattern is typical of a mature catalytic after-treatment field where the foundational chemistry was claimed years before newer entrants arrived.
No. Filing activity peaked at 62 records in 2018 and has declined since, with the 2022 midpoint down to 26. The most recent year shows very few filings, but that figure is understated because publication typically lags filing by around 18 months, so the true 2025-2026 filing level will only become clear once those applications publish. Even accounting for that lag, the multi-year trend from 2018 through 2022 is a clear decline rather than a plateau.
CO-SCR uses carbon monoxide, rather than ammonia or urea, as the reductant that converts NOx into nitrogen and water over a catalyst bed. The dataset's search terms center on oxygen tolerance, sulfur poisoning resistance, low-temperature activity and sintering resistance, all durability and performance concerns that recur across CO-based and ammonia-based SCR literature alike. The most-cited records in this space, including the foundational 1980s zeolite-catalyst patent, originate from the broader ammonia-SCR tradition that CO-SCR research has since drawn on and diverged from.
The clearest gaps sit outside the core catalyst-composition claims. Engine-control integration (F02D) appears on only 5.9% of records and combustion-residue handling (F23J) on just 1.1%, both far below the 64-69% share held by separation-process and catalysis classes. That imbalance suggests system-level claims pairing a control strategy or residue-management approach with an existing catalyst formulation are less contested than a new catalyst composition claim would be on its own.
Not directly. The highest-cited record in this dataset is a zeolite-catalyst patent from 1989 with 768 citations, far ahead of more recent filings, simply because older patents have had decades to accumulate citations within a searched corpus. Citation count is a reasonable proxy for a record's influence on the field's foundational chemistry, but it systematically understates the importance of recent filings that have not yet had time to be cited. Freedom-to-operate and white-space analysis should weight recent filing activity and claim scope more heavily than raw citation counts.
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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.