Characterization of VOC source profiles, chemical reactivity, and cancer risk associated with petrochemical industry processes in Southeast China

The petrochemical industry is one of the main sources of industrial volatile organic compounds (VOCs) emissions. In this study, typical petrochemical refining enterprises in Southeast China were selected, direct testing of VOCs in 18 petrochemical processes, and 87 samples were obtained using different on-site sampling methods, such as stack, fugitive, static and dynamic sealing point emissions sampling methods, based on the key process units, tank areas, loading and unloading areas, and plant boundaries of the petrochemical industry. Simultaneously, on-site concentration testing and laboratory analysis of 115 VOCs were conducted. Our findings reveal that, although the overall industry emission profile predominantly consists of low-carbon alkanes and alkenes, with relatively minimal halogenated hydrocarbon VOC emissions, there are substantial discrepancies in the primary species across different stages. The mass percentages of alkanes, alkenes, aromatics, halogenated hydrocarbons, and oxygenated VOCs in different process units of the petrochemical industry were 55 ± 27%, 8.5 ± 15%, 23 ± 27%, 3.9 ± 4.3%, and 10 ± 8.4%, respectively. The dominant species in the atmospheric vents of the depropanizer, light hydrocarbon recovery unit, continuous reforming unit, catalytic cracking unit, and sulfur recovery unit were n-butane (15%), n-hexane (13%), propane (21%), propylene (26%), and ethylene (28%), respectively. The dominant species in the gasoline tank top source profile was isopentane (48%), while that of the gasoline loading and unloading area was methyl tert-butyl ether (19%). High-carbon alkanes such as n-decane, n-octane, and n-heptane (>5% mass fractions) were prominent in kerosene tank tops. Furthermore, the results of the chemical reactivity assessment indicate that VOC emissions during the loading and unloading processes, as well as the ethylene production process, should be managed to mitigate ozone formation potential. According to the cancer risk assessments, benzene was the main factor that increased the risk, and its levels were far beyond the accepted cutoff point.