The field is highly concentrated: the top five assignees hold 580 of the 743 records in scope, or 78.1% of the field, with the single leading assignee alone accounting for 149 records. The drop-off is steep — by the tenth-ranked assignee, the count falls to 18 records. This means a small number of companies, largely refiners and petrochemical majors with pyrolysis-oil upgrading programmes, control most of the filed claim space, and any competitive or freedom-to-operate analysis should start with their portfolios rather than the full 60-company ranking.

Filings grew from 52 in 2017 to a peak of 236 in 2020, then, after cooling, resumed growth from 33 in 2021 to 105 in 2024 — a +218% increase over that three-year span, the last period unaffected by publication lag. Figures for 2025 and 2026 appear lower only because publication typically lags filing by around 18 months, not because activity has genuinely dropped. Read on that basis, the technology is still in an active claim-building phase rather than a mature, settling one.

Hydrocarbon oil refining and upgrading (IPC class C10G) appears on 87.3% of the 743 records in scope, making it by far the densest claim area. Coke and destructive distillation (C10B) follows at 22.9%, chemical and catalytic processes (B01J) at 16.0%, and acyclic/carbocyclic compound chemistry (C07C) at 13.3%. Because a single record can carry multiple IPC classes, these figures are not mutually exclusive and add up to more than 100% of the record total.

US20250019602A1, filed by SK Innovation and published in January 2025, describes waste plastic pyrolysis oil refining equipment that separates the feed into light and heavy oil streams, hydrotreats the light oil in a first reactor above 300°C and below 400°C with a hydrotreating catalyst, removes hydrogen chloride from the reaction product, and treats the heavy oil in a second reactor between 50°C and 300°C. It matters because this split light/heavy architecture with dedicated dechlorination is a recurring design pattern among the dataset's most-cited records, meaning new reactor-configuration claims in this space are likely to be checked against it as a reference point.

Relative to the crowded core of hydrocarbon oil refining and upgrading claims, sub-areas such as chlorine scavenger chemistry for mixed-feed oils, mass balance certification methodology, char formation control in continuous reactors, and separation-stage catalyst regeneration carry noticeably lower record counts in the technology composition data. These are not guaranteed to be open — a proper novelty search is still required — but they are the branches where filing density is thinnest relative to the core refining classifications, and where a first mover has more room to establish a claim position.