Multi-scale characterization of VOCs and CO2 emissions from the coking industry: an updated source profile and co-control framework.

The coking industry is a major source of volatile organic compounds (VOCs) and CO2, yet process-resolved VOCs-CO2 inventories remain lacking. Here, a comprehensive dataset of 110 VOC species from 20 processes was established. It is found that naphthalene was a dominant species in most samples (20-60%), and reached up to 95%, suggesting a great attention in future emission control efforts. By adopting an emission-weighted method, we further identified 68 new species, representing 67% of total VOCs, which are absent from the widely-used EPA SPECIATE profile, thereby significantly refining the existing source profile. A global inventory estimated coking VOCs and CO2 emissions at 1200 Gg and 380 Tg, of which China contributed more than 70% in total. A high-resolution inventory of China's 365 plants revealed strong spatial clustering, with four provinces contributing 53% in total. The process-based VOCs-CO2 integrated emission inventory showed that optimal co-benefits are achieved by controlling VOCs from by-product recovery and CO2 from coke-oven leakage. The analysis of co-benefit emission reduction efficiency (CEE) for four mitigation technologies revealed that "recovery upgrade" technology achieved simultaneous reductions of 145 Gg VOCs and 7079 Gg CO2 (CEE = 0.021), whereas "dry quenching replacing wet quenching" technology exhibited a negative co-benefit (CEE = -0.0083). This refined characterization provides critical data for improving the accuracy of emission inventories and atmospheric models, and highlights the urgent need to include naphthalene as a target in the future control strategies for the coking industry.