Filing activity peaked in 2020 at 90 records and has declined in most years since, falling to 44 by the 2022 midpoint and down to a handful by the partial 2026 count. That does not mean innovation has stopped, but the pace of new filings is clearly below its 2020 high. Because publication lags filing by roughly 18 months, the most recent one to two years will always look thinner than they eventually turn out to be, so treat the very latest figures as provisional rather than final.

The recent-year momentum data names UOP (Universal Oil Products), Mobil, ExxonMobil, Sinopec, and Lummus Technology among the most consistently active assignees historically, though all show zero filings in the latest tracked year. Sinopec and its research institutes also show the strongest internal co-filing relationships in the dataset, with one pair sharing 76 patent families. This suggests filing strength in this field is concentrated in a small number of long-established refining technology licensors and state-affiliated research institutes rather than spread across many new entrants.

US5616237A claims a fluid catalytic cracking process using multiple feed injection points along an FCC riser, where portions of the same fresh feed are split and charged at different points and temperatures along the riser's length. It is a process patent tied to split-feed injection specifically, not a claim over riser reactors generally. Anyone designing a new FCC riser feed system should check whether their injection scheme falls inside this split-temperature, multi-point structure before assuming it is clear, but riser designs using a single injection point or non-temperature-differentiated splits sit outside its literal scope.

The clearest under-claimed branches sit in the IPC subclasses with low record counts inside an otherwise dense corpus: B01D separation processes (31 records), C10L fuels (27), C01B inorganic compounds (26), C10M lubricants (23) and B05B spraying/atomising (16). These sit adjacent to the core C10G refining claims but are far less crowded, which points to opportunities in separation internals, catalyst regeneration flue-gas handling, and lubricant byproduct recovery. A targeted claim-chart search on these subclasses is a more reliable way to confirm genuine open space than relying on the low count alone.

Co-assignee data shows only 10 identified collaboration pairs across the entire 1,638-family corpus, and the three strongest are all internal to one corporate group — Sinopec filing jointly with its own research institutes. Outside that cluster, collaboration such as the Saudi Aramco and JGC Catalysts pairing (20 shared families) is comparatively rare. Combined with the fact that named leading assignees like UOP, ExxonMobil and Mobil show no filings in the latest year, this points to a field where a handful of incumbents built deep portfolios years ago and filing has since slowed across the board rather than shifted to new players.