Chemical Recycling Allocation Frameworks and Supply Chain Chain of Custody Integration
Mass balance credit verification demands tracing pyrolysis yields, deducting fuel losses, and enforcing physical site allocation rules on certified resin claims.
Proportional Physical Allocation
Meaning
Mass balance attribution models distribute recycled or bio-based material characteristics to co-products in direct proportion to their actual physical output ratios from a processing unit. In chemical recycling and co-feeding refining operations, proportional physical allocation determines the percentage of recycled content assigned to output polymer grades based on stoichiometric yield calculations. The attribution boundary excludes free-attribution models that assign recycled credits arbitrarily to high-value product lines without physical yield limits.
Allocation Model
Physical flow tracking dictates that output credits match the actual thermodynamic and mass yields of the conversion reactor. When applying proportional physical allocation to pyrolysis oil co-processing, the recycled content attributed to ethylene and propylene streams reflects their true mass fraction derived from the recycled feed. This methodology prevents over-attribution of sustainability claims to specific polymers while maintaining alignment with physical production realities.
Converters purchase certified resins whose attributed recycled content corresponds to physical plant balances.
Yield Accounting
Process losses and heavy residue formation reduce the mass available for polymer attribution. Precise yield accounting ensures that proportional physical allocation accounts for internal fuel consumption and gas losses during chemical cracking. Regrind blending in mechanical recycling follows similar conservation principles, where physical mass balances prevent double counting of recycled inputs across compounding lines.
Moulders rely on certified attribution ratios to document recycled content on customer specification sheets.
Verification Boundary
Auditing standards require continuous mass balance verification over defined operational periods, typically one calendar month. Independent certification bodies inspect site input-output balances to validate allocation integrity.