Ammonia Synthesis Patents: Who Leads, Where the Gaps Are 2026
- Concentration at the top. The top 5 assignees hold 65.5% of all 229 records in scope, and the top 10 hold 84.3% — this is a field with a short, well-defended leadership group.
- Filing has flattened, not accelerated. Volumes peaked in 2024 at 57 records after a slow build from 2017, and momentum among the leading assignees shows 0 filings in the latest year across several — a maturing claim space, not a growing one.
- Classification is heavily loop-and-separation, not just synthesis. C01C covers 96.5% of records, but B01D separation processes (12.7%) and F25J gas liquefaction (7.9%) mark smaller, less-crowded branches worth a closer look.
What this landscape covers
This dataset tracks 229 published records filed between 2015 and the 2026 data cut-off, drawn from patents and applications that combine ammonia synthesis or Haber-Bosch process language with specific technical anchors — iron or ruthenium catalyst chemistry, synthesis loop pressure control, purge gas recovery, energy-per-ton metrics and flexible operation. The scope is deliberately narrow: it is not every ammonia patent, but the subset where these operational and catalytic claims intersect.
Because publication typically lags filing by around 18 months, the most recent year of activity in any filing trend understates true filing volume — treat the last one or two years as a floor, not a ceiling.
Filing trends and technology composition
Two views of the same 229 records: how filing activity has moved year over year, and how those records distribute across IPC subclasses.
Filing trend, 2017–2026
Filings sat at 0 in 2017, rose through the decade and peaked at 57 in 2024. The 2022 midpoint of 12 confirms the growth was not steady — most volume arrived in the final few years before flattening, with the partial 2026 count reflecting publication lag rather than a real drop-off.
IPC subclass distribution
C01C dominates at 96.5% of the 229 records in scope, confirming this is fundamentally an ammonia-and-nitrogen-compound corpus. C01B (42.4%) and C07C (24.5%) show heavy overlap with adjacent inorganic and carbocyclic synthesis-gas chemistry, while B01J catalysis (16.6%), B01D separation (12.7%), C25B electrolytic production (11.8%), F25J gas liquefaction (7.9%) and C10J gasification (3.5%) mark the smaller, more specialised branches where claim density thins out.
Shares are the percentage of the 229 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Ammonia Synthesis (Haber-Bosch) with Eureka
This page is one run against one query. Ask Eureka your own question about ammonia synthesis (haber-bosch) and every answer comes back with the patent numbers behind it.
Try EurekaThe most-cited records in this field
Purge Control for Ammonia Plant
Control of the synthesis loop pressure of an ammonia plant is accomplished by automatically changing the purge rate of the recycle gas to maintain optimum synthesis loop pressure. The control logic allows compressor speed to be set at a constant value while suction pressure to the first stage of the synthesis loop compressor is maintained by changing the purge rate of the recycle gas — letting the loop pressure seek the highest possible value at given feed rates and compressor speed to assure optimum compressor loading.Filed 1981-12-15 by Applied Automation, Inc. — a control-logic patent that still shapes how purge rate and loop pressure are claimed today.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US4296085A | Process for the production of ammonia and the corresponding synthesis gas | 124 |
| 2 | US5180570A | Integrated process for making methanol and ammonia | 102 |
| 3 | CA1187702A | Process for converting coal and/or heavy petroleum fractions into hydrogen or ammonia synthesis gas | 52 |
| 4 | US4126668A | Production of hydrogen rich gas by combined steam reforming and intermediate oxidation-reduction | 47 |
| 5 | US4524056A | Process for the production of ammonia | 39 |
| 6 | WO2020150245A1 | Use of renewable energy in ammonia synthesis | 28 |
| 7 | US20220119269A1 | Use of renewable energy in ammonia synthesis | 26 |
| 8 | US5114694A | Ammonia recovery from purge gas | 25 |
| 9 | US4148866A | Low energy ammonia synthesis process | 25 |
| 10 | EP3730456A1 | Use of renewable energy in ammonia synthesis | 23 |
Ranked by citation count within the searched corpus. Older grants dominate this list by construction — citation counts accumulate over time, so treat this as a signal of foundational influence, not of what matters today.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Three read-throughs from the concentration, classification and citation figures above.
A short list of entities controls most of the field
With the top 5 assignees holding 65.5% of all 229 records and the top 10 holding 84.3%, this is not a fragmented emerging field — it is a mature process area where a handful of engineering-contractor and catalyst licensors already hold dense claim positions.
Filing has cooled among the historical leaders
Several of the most active historical assignees show 0 filings in the latest tracked year, some with a -100% year-on-year change. Combined with the 2024 peak of 57 records, this points to a plateau in core synthesis-loop and catalyst claims rather than continued expansion.
Claim density falls off sharply outside the core class
Almost every record touches C01C, but separation (B01D, 12.7%), electrolytic production (C25B, 11.8%) and gas liquefaction (F25J, 7.9%) cover a much smaller share of the same 229 records — these are the branches where fewer filings compete for the same claim territory.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to ammonia synthesis (haber-bosch), with the prior art for and against each one.
The assignee landscape
47 companies appear in the ranked assignee list behind this dataset — the full ranking the data endpoint returns, not a top-50 or top-100 cut. The leader holds 68 records; by fifth place that falls to 11, and by tenth place to 7, which is consistent with the 65.5%/84.3% concentration figures above.
One filer sits well ahead of the field
The top-ranked assignee holds 68 records against a fifth-place figure of just 11 — a gap wide enough that any competitive read of this space starts with understanding that single portfolio's claim structure before anything else.
A steep drop-off after the leader, then a long plateau
Volume drops sharply from the leader to fifth place, then flattens — rank 10 sits at 7 records, not far below rank 5's 11. That plateau is where most of the ranked 47 companies sit, each with a handful of filings rather than a defensible position.
Historical leaders have gone quiet in the latest tracked year
Multiple assignees that built large historical portfolios — including several with -100% year-on-year change — show no filings in the most recent year. That does not necessarily mean disengagement; publication lag means recent filings may not yet be visible.
| Assignee | Recent year | YoY |
|---|---|---|
| Haldor Topsoe A/S | 0 | — |
| SK Innovation Co., Ltd. | 0 | — |
| Casale SA | 0 | -100% |
| Kellogg Brown & Root Inc. | 0 | — |
| Mosaic Co. | 0 | -100% |
| SABIC Global Technologies B.V. | 0 | -100% |
| Foster Wheeler Energy Corp. | 0 | — |
| Stamicarbon B.V. | 0 | -100% |
Where to take this analysis
The dataset points to specific next steps depending on what a reader needs to decide.
Map freedom-to-operate in thinner branches
Separation (B01D), electrolytic feed integration (C25B) and gas liquefaction (F25J) carry far fewer of the 229 records than the core C01C class — a targeted FTO search in these branches costs less and returns clearer answers.
Explore in EurekaTrack the leader's portfolio in detail
With 68 records against 11 at fifth place, the leading assignee's claim structure sets the boundary most new filings will need to clear.
Run an assignee deep-diveWatch for renewed filing after the plateau
Several top historical filers show 0 activity in the latest year; because publication lags filing by roughly 18 months, it is too early to call this a retreat rather than a lag artifact.
Set up monitoring in EurekaCommon questions about ammonia synthesis patents
The assignee ranking behind this dataset covers 47 companies, and it is heavily concentrated: the top 5 hold 65.5% of all 229 records in scope, and the top 10 hold 84.3%. The single leading assignee holds 68 records, well ahead of the fifth-ranked firm at 11. In practice this means a small group of engineering contractors and catalyst licensors control most of the documented claim space, with a long tail of companies holding only a handful of filings each.
Filing activity in this dataset rose from 0 in 2017 to a peak of 57 records in 2024, but the midpoint year of 2022 sat at only 12, showing the growth was concentrated late rather than steady throughout the period. Several of the most active historical assignees show 0 filings in the most recent tracked year, some with a -100% year-on-year change, suggesting the field has plateaued rather than continuing to accelerate. Because publication lags filing by roughly 18 months, the very latest year should be read as incomplete rather than as a genuine slowdown.
US4296085A, titled 'Process for the production of ammonia and the corresponding synthesis gas', is the most-cited record in this dataset with 124 citations. Its influence reflects its age and foundational position in synthesis gas production for ammonia plants rather than current commercial relevance. Anyone doing freedom-to-operate work in this space should review it as a baseline reference point, not assume it defines the current state of the art.
Within the same 229-record dataset, classes like gas liquefaction and separation (F25J, 7.9% of records), electrolytic production (C25B, 11.8%) and separation processes (B01D, 12.7%) carry far fewer filings than the dominant ammonia and nitrogen compound class (C01C, 96.5%). These smaller shares mark technical branches — such as electrolytic hydrogen feed integration or flexible load-following operation — where claim density is lower and there is more room to file a differentiated first claim.
US4305918A, 'Purge Control for Ammonia Plant', claims a control method that sets compressor speed constant and manages synthesis loop pressure by varying purge rate of the recycle gas to keep suction pressure optimal. This specific mechanism — constant compressor speed paired with purge-rate-driven pressure control — is the part a new filing needs to avoid or meaningfully differentiate. Alternative approaches, such as variable compressor speed control or pressure control via feed rate rather than purge rate, sit outside this specific claim structure.
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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.