某工业园区VOCs臭氧生成潜势及优控物种

臭氧(O3)污染日趋严重,控制光化学反应前体物之一的挥发性有机污染物(volatile organic compounds,VOCs)对减少臭氧生成有重要意义.为研究天津某工业园区VOCs臭氧生成潜势,采集了园区6个代表企业厂界气体样品,使用质子转移反应飞行时间质谱仪(PTR-TOF-MS)对VOCs进行了定量分析,估算了各企业臭氧生成潜势,运用VOCs/NO_x研究了臭氧生成控制敏感性因素,并在熵值法基础上筛选出了减少臭氧生成优先控制VOCs物种.结果表明,通过PEC法估算臭氧生成F企业最高为0.423 3 mg·m~(-3),MIR法估算结果 C企业最高为1.573 3 mg·m~(-3);PEC法估算结果与臭氧浓度更接近,适用于园区对臭氧生成的估算;VOCs和NOx均为工业园区臭氧生成敏感性因素,需同时控制;园区内VOCs物种臭氧生成贡献大小为烷烃烯炔烃醇类芳香烃,优先控制物种为正庚烷及其同分异构体、正壬烷、正辛烷及其同分异构体、正十一烷、戊烷、正癸烷、甲醇.

Ozone Formation Potential and Priority Species of VOCs in an Industrial Park

Ground-level ozone (O₃) pollution is a serious problem in major cities in China. The control of its precursors, volatile organic compounds (VOCs), is a key to limiting ozone production. The ozone formation potential of VOCs in an industrial park in Tianjin was studied by collecting gas samples at the factory boundaries of six representative enterprises. The PTR-TOF-MS was used to analyze VOCs quantitatively. The VOCs/NO_x ratio was used to determine the control strategies. The priority VOCs were selected based on the entropy method. Our results indicated that, the ozone formation potential concentration of enterprise F was the highest with the concentration of 0.4233 mg·m^-3 using the propylene-equivalent concentration (PEC) scale; the highest concentration was obtained at enterprise C with 1.5733 mg·m^-3 using maximum incremental reactivity(MIR) scale. The result of PEC scale is closer to the O₃ concentration, which is applicable to the study of ozone generation in this industrial park. Ozone production is sensitive to both VOCs and NO_x in this industrial park, joint control should be considered. Alkanes contributed most to ozone formation, followed by alkenes & alkynes, alcohols, and aromatics. The prior VOC species that need to be controlled include n-heptane and its isomers, n-nonane, n-octane and its isomers, undecane, pentane, n-decane, and methanol.