Emission characteristics, source profiles, inventories, and future emissions of volatile organic compounds from the Chinese coking industry.

Volatile organic compounds (VOCs) from coke production originate from multiple stacks and fugitive sources. However, process-specific compositions and reactivities remain poorly characterized. Coke-oven chimney, topside, and near-plant ambient samples were collected from two newly commissioned large-scale top-charging coking plants, and 116 VOC species were quantified using gas chromatography-mass spectrometry/flame ionization detection (GC-MS/FID). During the sampled operating periods, the measurement-derived coke-oven-chimney VOC emission factors were 0.077 and 0.117 g/kg coke for Plants A and B, respectively. Their production-weighted estimate (0.097 g/kg coke) was used as a provisional input for the chimney component of the literature-integrated inventory. A 121-species composite profile was constructed by harmonizing measurements from this study with published profiles. Quantified values were retained, reported non-detects were assigned a value of zero, and unreported or unmeasured species were excluded from the species-specific mean calculations. Process- and species-resolved VOC emission inventories for 2012-2020 were developed using dynamic emission factors and plant-level activity data. Alkenes accounted for 61.3% of the measured VOC mass in the coke-oven-chimney samples. Oxygenated VOCs accounted for 52.02-60.97% of the total VOCs in the topside samples, although this enrichment is interpreted as indicative because field/transport blanks and compound-specific aldehyde storage-recovery tests were unavailable. National VOC emissions were 800.8 kt in 2020, with a 95% uncertainty interval of -43.3 to +71.8%. Coke-oven leakage and condensation and cooling contributed 33.4% and 29.2% of the emission-weighted ozone formation potential (OFP), respectively, whereas condensation and cooling, coke-oven leakage, and desulfurization contributed 84.7% to the secondary organic aerosol potential (SOAP). These indicators represent standardized formation potentials rather than modeled ambient ozone (O3) or secondary organic aerosol (SOA) responses. Illustrative scenarios indicated larger emission reductions under stronger control pathways, although the projections remained conditional on coke demand and control-technology assumptions. The results identified fugitive leakage and aromatic-rich gas-purification processes as priorities for VOC mitigation.