Sulfur Removal and Recovery Patents: Who Leads, White Space 2026
- Filing peaked in 2020 at 107 records and has fallen sharply since — 2021's 42 filings dropped to 17 by 2024, a 60% decline over that three-year span.
- The top 5 assignees hold 30.1% of all 1,463 records while the top 10 combined reach 44.4%, leaving a long tail of single- and few-filing entrants below them.
- C01B and B01D dominate the classification mix at 77.0% and 60.1% of records respectively, showing claim density concentrated in core chemistry and separation steps rather than downstream integration.
Filing growth compares 2021 (42 records) with 2024 (17) — 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 1,463 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
This landscape tracks patent activity around sulfur recovery units, the Claus process and its tail-gas treatment variants, together with adjacent routes such as liquid redox and catalyst sulfation. The scope spans 1,463 published records from 2015 through the mid-2026 data cut-off, capturing both the core thermal/catalytic Claus chemistry and the separation hardware — condensers, reheaters, converters — that surrounds it. Because publication lags filing by roughly 18 months, the most recent one to two years in any trend understate real filing activity.
The field sits at the intersection of refining, gas processing and environmental compliance, so filings come from oil majors, licensors of Claus technology, and specialist gas-treatment engineering firms alike. Family-level counts, rather than raw document counts, are the fairer measure here because continuation filings and multi-jurisdiction filing practices vary widely across this applicant mix.
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Filing trends and technology composition
Two views of the same 1,463-record dataset: activity over time, and where the claims sit across IPC subclasses.
Filing activity, 2017-2026
Filings rose to a peak of 107 in 2020, then declined — 2021's 42 fell to 17 by 2024, a 60% drop over that three-year window. 2025 and 2026 figures are still incomplete due to publication lag and should not be read as a continuation of the decline.
Technology composition by IPC subclass
C01B (non-metallic elements and inorganic compounds) appears on 77.0% of records and B01D (separation processes) on 60.1%, confirming that most claims sit in core sulfur chemistry and gas separation. Downstream applications — purifying fuel gases (C10K), fuels (C10L), combustion (F23C), refining (C10G) and gasification (C10J) — each sit under 4% of records, marking them as comparatively open ground.
Shares are the percentage of the 1,463 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Sulfur Removal and Recovery with Eureka
This page is one run against one query. Ask Eureka your own question about sulfur removal and recovery and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative filing and most-cited prior art
Sulfur recovery unit oxidation air management during SuperClaus to Claus switching
Described is a control process for oxidation air management in a sulfur recovery unit. The unit includes a gas feedstock inlet, an oxidation air inlet, a reaction furnace, pre-heaters, a Claus section including multiple sulfur condensers and Claus converters, and a SuperClaus section including a catalyzing SuperClaus converter, sulfur condenser, and oxidation air flow control valve. The control process analyzes operating parameters to determine when to switch from the SuperClaus section to the Claus section, with continuous monitoring of conditions in the unit.Filed by Saudi Arabian Oil Company, published 2023-10-03.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US4017272A | Process for gasifying solid carbonaceous fuel | 155 |
| 2 | US4311683A | Process for removal of hydrogen sulfide from gas streams | 133 |
| 3 | US20030194366A1 | Catalysts and process for oxidizing hydrogen sulfide to sulfur dioxide and sulfur | 123 |
| 4 | US5407466A | Sour gas treatment process including membrane and non-membrane treatment steps | 115 |
| 5 | US5738834A | System for removal of hydrogen sulfide from a gas stream | 113 |
| 6 | US5401300A | Sour gas treatment process including dehydration of the gas stream | 113 |
| 7 | US5733516A | Process for removal of hydrogen sulfide from a gas stream | 107 |
| 8 | US6099819A | Catalysts for the selective oxidation of hydrogen sulfide to sulfur | 102 |
| 9 | US4552747A | Temperature moderation of an oxygen enriched Claus sulfur plant | 92 |
| 10 | US20150377079A1 | Energy efficient apparatus employing energy efficient process schemes providing enhanced integration of gasif… | 91 |
Citation counts reflect influence within the searched corpus and favour older filings; they are not a measure of current commercial relevance.
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Three patterns worth acting on before drafting or licensing decisions.
Filing sits with a small group of majors and licensors
The top 5 assignees combined hold 30.1% of all records in scope, and the top 10 reach 44.4%. Below that line sits a long tail of single- and few-filing entrants, typical of a field anchored by refining majors and process licensors rather than a fragmented startup base.
Post-peak decline, but read the tail carefully
Filing peaked at 107 records in 2020 and fell to 17 by 2024, a 60% drop across that three-year span. 2025-2026 figures are still filling in due to publication lag and should not be read as evidence the field has gone quiet.
Claims cluster in core chemistry, not downstream integration
C01B and B01D between them cover the bulk of records, meaning most claim space is occupied at the level of sulfur chemistry and separation hardware. Combustion, fuel purification and gasification classes each sit under 4%, pointing to integration and downstream use as comparatively open territory.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to sulfur removal and recovery, with the prior art for and against each one.
Leading assignees and where they are pulling back
The ranked leaders include 100 companies; the picture below covers the leader, the concentration at the top, and where recent-year activity has slowed even among the largest filers.
A single filer sits well ahead of the field
The leading assignee holds 138 records, well clear of fifth place at 64 and tenth place at 30 — a steep drop-off that marks this as a leader-plus-tail structure rather than an even spread.
Even major filers show near-zero recent-year output
Several of the largest historical filers, including the leading assignee, show zero filings in the latest year, with one recording a -100% year-on-year change. This is consistent with publication lag rather than necessarily a retreat from the technology.
Co-filing is limited and concentrated
Only 10 co-assignee pairs appear in the dataset, and the strongest pairings are internal — a major oil producer filing jointly with its own affiliated service arm, and a refiner filing repeatedly with named individual inventors. Cross-company joint filing is rare in this field.
| Assignee | Recent year | YoY |
|---|---|---|
| Shell Internationale Research Maatschappij B.V. | 1 | — |
| Saudi Arabian Oil Co. | 0 | -100% |
| Haldor Topsoe A/S | 0 | — |
| ConocoPhillips Co. | 0 | — |
| Fluor Tech Corp. | 0 | — |
| Amoco Corp. | 0 | — |
| Air Products and Chemicals, Inc. | 0 | — |
| Mobil Oil Corporation | 0 | — |
Where to take this analysis
The dataset points to a field with dense core claims and thinner downstream coverage. Turning that into a filing or freedom-to-operate decision means going record by record.
Map claim boundaries in the core classes
C01B and B01D carry the bulk of filing density; a claim chart against the most-cited records in those classes will show what is actually blocked versus assumed blocked.
Explore claims in EurekaTest the under-claimed branches
Reheater arrangements, sulfur degassing control and catalyst sulfation resistance show low filing density relative to the core — worth a targeted prior-art pull before drafting.
Run a white space searchCommon questions on sulfur recovery patents
One assignee leads the field with 138 records, well ahead of fifth place at 64 and tenth place at 30, so the field has a clear leader rather than an even spread. The top 5 assignees together hold 30.1% of all 1,463 records in scope, and the top 10 reach 44.4%. Below that concentration sits a long tail of companies with only a handful of filings each, which is typical of a field anchored by refining majors and process licensors rather than a fragmented field of specialist startups.
Filing peaked at 107 records in 2020 and declined afterward, with 2021's 42 filings falling to 17 by 2024 — a 60% drop over that three-year span. That said, patent publication typically lags filing by around 18 months, so the 2025 and 2026 figures in any dataset are still incomplete and should not be read as continuing the decline. Treat 2024 as the most recent year with a reasonably complete picture.
The dominant classes are C01B, covering non-metallic elements and inorganic compounds, which appears on 77.0% of the 1,463 records in scope, and B01D, covering separation processes, on 60.1%. B01J, chemical and physical processes including catalysis, appears on 27.3% of records. Downstream-facing classes such as fuel gas purification, fuel treatment, combustion apparatus, oil refining and gasification each sit under 4% of records, indicating those areas carry far fewer competing claims.
The classification data shows heavy concentration in core sulfur chemistry and separation hardware, with C01B and B01D together covering most of the dataset. Sub-areas named directly in the search scope but rarely dominant in the classification mix — reheater arrangement design, sulfur degassing process control, catalyst sulfation resistance, and liquid redox integration with Claus tail gas streams — show comparatively thin coverage and are worth a targeted freedom-to-operate check before drafting new claims there.
Co-filing is limited: the dataset identifies only 10 co-assignee pairs across 1,463 records. The strongest of these pairings are internal rather than cross-company, such as a major oil producer filing jointly with its own affiliated service subsidiary, or a refiner filing repeatedly alongside named individual inventors. This suggests most patent strategy in the field is executed by single corporate assignees rather than through joint ventures or formal co-development filings.
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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.