[Chemical Composition of VOCs from Service Stations Vapor Processing Device and Associated Contributions to Secondary Pollution]

Abstract

Vapor processing device is a device that can control the headspace pressure in the underground storage tanks and recover the vapor. By analyzing the chemical composition of volatile organic compounds (VOCs) at the inlet and outlet of the vapor processing device, the ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAP) were estimated by maximum incremental reaction (MIR) and fractional aerosol coefficients (FAC), and the secondary pollution formation contribution of VOCs were quantitatively evaluated. The results showed that:① the ρ(total volatile organic compounds, TVOC) at the inlet and outlet of the vapor processing device were 436-706 g·m^-3 and 4.98-10.04 g·m^-3, respectively. Alkanes (72%±4%), oxygenated organics (14%±2%), and olefins (11%±5%) were the dominant components of VOCs emissions. There were little differences in VOCs emissions from the different vapor processing devices; the key species were i-pentane (approximately 25%), followed by n-butane, i-butane, and n-pentane. ② The ozone source reactivity (SR) of VOCs emissions from the outlet of the vapor processing device was 2.6-3.3 g·g^-1, and the OFP was 3.5-25.6 g·m^-3. Olefins contributed the most (43%-69%), followed by alkanes (20%-35%) and oxygenated organics (10%-22%). Butene, cis-2-butene, trans-2-butene, i-pentane, and propionaldehyde were the species that highly contributed to OFP. ③ Aromatics in VOCs emissions contributed the most to SOAP (80%-92%), and the main active species were toluene, 1, 2, 4-trimethylbenzene, 1, 3, 5-trimethylbenzene, and p-diethylbenzene. The research showed that different VOCs species emitted by the vapor processing device contributed obvious differences to the secondary atmospheric pollution, and butene species and aromatics such as toluene were the focus of VOCs emission control of vehicle gasoline and vapor processing device.

Keywords: ozone formation potential(OFP); secondary organic aerosol formation potential(SOAP); service stations; vapor processing device; volatile organic compounds(VOCs).