Analysis Of The Source Spectrum Of Volatile Organic Compounds In Petroleum Refining Processes

Volatile organic compounds(VOCs)are important precursors of atmospheric pollutants of O₃and secondary organic aerosol(SOA).The analysis of VOCs composition in air samples at monitoring sites is the basic data for establishing VOCs emission source list and operating air quality model,which is of great significance for understanding the source of VOCs in the atmosphere and evaluating their contribution to the generation of ozone and fine particles.In this study,a method based on thermal desorption-gas chromatography-mass spectrometry was developed for the simultaneous analysis of 67 VOCs.Sixty-seven target compounds and non-target compounds were screened for unorganized sources of VOCs in the process of a petroleum smelting enterprise with this method,and the ozone formation potential(OFP)and SOA formation potential of them were evaluated.The research results are listed as follows:?A total of 16 target VOCs and 54 non-target VOCs were detected.The proportion of total non-target compounds to the total mass concentration of VOCs at each monitoring site was 63.0%.?The concentration levels of total volatile organic compounds(TVOCs)detected at the 15 monitoring sites ranging from 32.1 to 1206.4?g/m³.Among them,sewage treatment area,product tank area and second distillation unit area contributed a large amount to VOCs unorganized emission.?The VOCs unorganized emission source spectrum is composed of alkanes,alkenes,oxygen-containing volatile organic compounds(OVOCs),aromatics and other nitrogen-containing sulfur compounds.Among them,alkanes and OVOCs have the highest content.At various monitoring points,there were a wide distribution of n-hexane,isopentane,acetone,dichloromethane,toluene,n-pentane and m-/p-xylene,and a higher content of methyl tert-butyl ether,n-hexane,isopentane,2-butanone,toluene,n-pentane,benzene,acetone,2-methylpentane and m-xylene.There was the most content of methyl tert-butyl ether in the product tank area.?The OFP of VOCs was assessed using the maximum incremental activity factor weighting method.The characteristic pollutants that contribute significantly to ozone formation were toluene,paraxylene,m-xylene,methyl tert-butyl ether,hexane,isopentane,2-butanone and o-xylene.There were larger OFP values at the wastewater treatment area,secondary distillation plant area,and product tank area.Alkanes and aromatic hydrocarbons had larger OFP values than the other components.?The SOA formation potential of VOCs was evaluated by the aerosol formation coefficient method.The compounds that contributed significantly to the SOA formation potential and were widely distributed were mainly benzene series compounds.The SOA generation potential of unorganized emission VOCs in sewage treatment area was the largest,accounting for 51.2%of the total SOA generation potential.