Filing is concentrated at the top: the leading assignee alone holds 485 of the 3,999 records in scope, and the top 5 assignees combined account for 36.9% of all records. These leaders are established industrial gas and chemical engineering firms with long-running pressure swing adsorption and gas-separation portfolios. Below the top 10, which together hold 47.9% of records, ownership spreads across a long tail of research institutes and single-filing entrants, so the field is not a closed two-player market despite the concentration at the very top.

The IPC composition shows B01D, the separation-processes class covering both PSA and membrane filtration equipment, on 74.1% of the 3,999 records, making it by far the dominant technical route in claim volume. C01B, non-metallic elements and inorganic compounds, appears on 48.4% of records and often overlaps with B01D filings on the same hardware. The data does not break PSA out separately from membrane separation at the class level, so a claim-by-claim review is needed to judge the split between the two within B01D.

Annual filings rose from 100 in 2017 to a peak of 178 in 2022, then declined toward 15 in the partial 2026 count. Part of that drop is a publication-lag artefact: patents typically publish roughly 18 months after filing, so the last one to two years of any trend line will always look lower than they eventually turn out to be. Even allowing for that lag, the multi-year decline from the 2022 peak suggests the core adsorption and membrane equipment claim space has filled in, pushing new filings toward narrower ammonia-specific and carrier-stream variants rather than broad separation hardware.

The clearest gap is ammonia-specific chemistry: C01C, the class for ammonia, cyanides and nitrogen compounds, appears on only 5.4% of the 3,999 records, far below the 74.1% carried by generic separation processes. Given that ammonia decomposition is a named route in this dataset's own search criteria, that low share points to under-claimed territory in adsorbent selection for nitrogen/ammonia co-removal, cycle-time control across multi-bed PSA systems handling carrier off-gas, and mechanical support design for membrane modules in these specific streams. Filers willing to draft claims tied to carrier-stream conditions rather than generic gas mixtures have more room to work with here.

The United States leads with 832 filings, ahead of China at 647 and the European Patent Office at 635. Canada, the WIPO/PCT route and India follow at lower volumes. Because no single office accounts for a majority of filings, a thorough freedom-to-operate or licensing review in this field needs to cover at least the US, China and EPO jurisdictions rather than relying on any one office as a proxy for the whole landscape.