化工企业优控VOCs污染物分析及生成机理

以山东省某化工企业为研究对象，采用气袋法对企业正常工况条件下有组织和无组织排放点进行了样品采集，使用车载气相色谱/飞行时间质谱（GC-TOF-MS）对企业排放的VOCs进行了定量分析.结果表明，企业的有组织和无组织排放VOCs浓度范围分别为0.562~9.629，0.789~1.212mg/m³，两种情况下排放浓度较高的10种VOCs的物质截然不同，但无组织检出浓度较高的物质都在有组织总排放口中检出.采用3种方法分别估算了企业排放VOCs的臭氧生成潜势（OFP），根据OFP值筛选出企业十大优控污染物，主要为芳香烃和含硫/氧有机物.通过化学理论分析和量子化学分子模拟计算出分子的最低空轨道与自由基的最高占有轨道的能量差，发现VOCs更容易跟甲基自由基反应形成长链烷烃和芳香烃，与检测出的优控VOCs污染物相一致.

Determination and formation mechanism of precedence-controlled VOCs pollutants in chemical plant

A chemical enterprise in Shandong province was chosen as a research object to quantitatively analyze the emission characteristics of VOCs. To carry out the study, samples from both organized and unorganized emissions were collected under normal operating conditions using the bags method. The mass concentration of VOCs was obtained using GC-TOF-MS technology. The results showed that the mass concentration of VOCs in the organized samples and unorganized samples was 0.562~9.629mg/m³ and 0.789~1.212mg/m³, respectively. The 10 pollutants with high mass concentrations of VOCs were different between the organized and unorganized samples. Interestingly, the top 10 pollutants in unorganized samples were also determined in the organized samples from the total exhaust emissions outlet. In addition, three methods were used to evaluate the Ozone Formation Potential (OFP) of VOCs to determine the top 10 precedence-controlled VOC pollutants. According to the evaluation results, the major VOC pollutants were aromatic hydrocarbons and sulfur/oxygen compounds. Chemical theoretical analysis and quantum chemistry method were used to calculate the energy difference between the lowest unoccupied orbital of the molecule and the highest occupied orbital of the free radical. It was found that VOCs preferred to react with methyl radicals to form long-chain alkanes and aromatic hydrocarbons. The theoretical analysis results were agreement with the experimental phenomenon that the precedence-controlled VOCs pollutants were detected in the organized emissions.