Filing volume peaked at 40 records in 2018 and had fallen to 15 by the 2022 midpoint, with a flat-to-declining trend since. That said, publication lag of roughly 18 months means the last one to two years in the dataset understate true filing activity, so the most recent apparent drop should not be read as a hard stop. The more reliable read is that the core architecture claims were staked out earlier in the period, and new activity is now concentrated at narrower integration points rather than across the whole field.

Johnson Matthey and BASF show the strongest filing and co-assignee activity in this dataset, each structuring filings across multiple national entities — Johnson Matthey between its UK holding company and German catalyst subsidiary, BASF across its corporate, stock-company, and China subsidiary. Engelhard, Mobil Oil and Furukawa Electric also appear among the historically active assignees. All of these show zero filings in the most recent year in this corpus, which may reflect real slowdown, publication lag, or a shift in filing strategy.

The United States and the European Patent Office dominate, with 174 and 147 filings respectively — together accounting for more than half of all filings in the dataset. WIPO PCT filings (50) and China (43) trail well behind, with Canada and the UK smaller still. A freedom-to-operate review should prioritise US and EU prosecution history first, then extend to PCT and China filings for global manufacturing or export exposure.

Every record in this dataset falls under B01J (catalytic and physical processes), but a large share also cross into B01D separation processes (239 records) and F01N exhaust treatment (131 records). That overlap means the contested claim space is not just the zeolite formulation itself but how it is packaged, housed, and integrated into a separation or exhaust system. A filer focused purely on catalyst chemistry without checking these adjacent classes risks missing the claims that actually block commercialization.

Not necessarily — citation counts in any patent corpus favour older filings simply because they have had more time to accumulate citations. The five most-cited records here are all pre-2003 filings on diesel exhaust catalysts and selectivated zeolite processes for aromatic chemistry. They matter as foundational prior art and freedom-to-operate reference points, but they are not a reliable guide to which technical routes are being actively pursued now.