In this dataset, a record is captured when it combines flow-reactor terminology (continuous flow reactor, microreactor synthesis) with process-intensification language such as residence time, heat transfer, or scale-up numbering up, under IPC codes B01J19, B01F33 or C07B61. A batch process patent that happens to mention heat transfer would not qualify unless it also claims a continuous flow configuration. The distinction matters for freedom-to-operate work because many chemistries are claimed in both batch and flow variants by different assignees.

Filings rose to 37 in 2018, the high point of this window, then eased to a midpoint of 17 by 2022. This pattern is typical of a technology where the core reactor architectures — the equipment claims captured heavily under IPC B01J — were substantially staked out earlier in the decade, leaving later filers to compete for narrower process-condition or application-specific claims. Remember that publication lags filing by roughly 18 months, so the most recent one or two years in this trend will always look thinner than they eventually turn out to be.

The most-cited record in this corpus, US5580523A on integrated chemical synthesizers, has accumulated 592 citations and predates most of the filing activity tracked here, making it a foundational reference rather than a recent filing. Beyond citation counts, co-assignee data shows a small number of durable pairings — most notably a national research organisation filing repeatedly alongside an industrial partner — pointing to sustained joint programmes rather than a single dominant commercial filer. A full assignee ranking with family counts is rendered separately on this page.

The IPC composition shows B01J (chemical and physical processes) present in the large majority of families, while related sub-areas — in-line analytics integration, numbering-up manifold design, multi-phase gas-liquid microreactors, and flow synthesis of heterocyclic compounds under C07D — appear far less often. That lighter density does not guarantee an easy filing, but it suggests these branches have not been as heavily claimed as core reactor hardware, making them worth a targeted prior-art search before committing to a design.

The filing trend and recent-year momentum data both point toward maturity rather than continued growth: the 2018 peak of 37 families has not been matched since, the 2022 midpoint of 17 is roughly half that, and every one of the top tracked assignees shows zero filings in the latest year. That said, the ~18-month publication lag means the very latest year understates real activity, and a moderate total of 266 families over the window is not so large that meaningful claim space is fully exhausted.