| 摘要: | 六氯苯（HeCB）是持久性有機污染物(POPs)之一，儘管全球在幾十年前已限制HeCB的產生，其仍存留於環境中，然而現今關於去除HeCB的研究很少。為了分析過程中產生的中間產物，改進分析氯苯同系物的方法，目前已成功分析氯苯同系物(三氯至六氯)。本研究中探討商業用觸媒 V2O5-WO3/TiO2 對六氯苯的去除效率，當反應溫度為160oC～200oC時，乾燥條件下200℃時HeCB去除效率可達99%，在此溫度範圍內，存在水蒸氣 (20%) 時，200oC 下最高去除效率達 94%，因此高溫可以提高觸媒活性，在較高溫度，乾燥條件及濕潤條件下去除效率從 160oC 的 8% 下降到 200oC 的 5%，代表可以克服蒸氣含量對觸媒的不利影響。但水蒸氣仍被認為是抑制 V2O5-WO3/TiO2 觸媒性能的因素。根據初步結果，1,2,4-TriCB 是在觸媒破壞過程中產生的主要含氯化合物，幾乎可全部被吸附在觸媒上，在乾燥條件及濕潤條件下，氣流和觸媒中1,2,4-TriCB 的最高總質量分別為 0.7 µg 和 0.8 µg。透過計算氯質量平衡，發現在沒有水蒸氣的情況下有35% 的氯原子不存在於含氯化合物中，若通入氣流含有水蒸氣則該值為 20%。因此，蒸氣會影響觸媒將含氯化合物破壞為 Cl2 的能力。對於HeCB而言，溫度與觸媒吸附能力呈正相關。目前該領域的研究文獻並不多，需進行更多的實驗數據來證實。;Hexachlorobenzene (HeCB) is one of the notorious persistent organic pollutants (POPs). Even though its production was restricted worldwide decades ago, HeCB still remains in the environment. However, there is a scarcity of studies conducted on HeCB removal. To assist in analyzing intermediates produced in the destruction process, a method of analyzing chlorobenzene congeners has been improved. Up to now, the procedure has been successful in the analysis of chlorobenzene congeners (from tri- to hexa-). In this research, the catalytic performance of commercial V2O5-WO3/TiO2 in HeCB destruction has been studied. When the reactor temperature ranges from 160oC to 200oC, the peak of HeCB removal efficiency could be up to 99% at 200oC in the dry condition. With water vapor (20%) and in this temperature range, the highest removal efficiency was 94% at 200oC. Therefore, high temperatures can enhance catalytic activity. At higher temperatures, the gap between removal efficiencies in dry and wet conditions declines from 8% at 160oC to 5% at 200oC, which means the adverse effect of steam content on the catalyst can also be overcome. However, water vapor is still considered the factor that inhibits the catalytic performance of V2O5-WO3/TiO2. Based on the preliminary results. 1,2,4-TriCB predominates in the chlorinated by-products during catalytic destruction, and it could be almost adsorbed on the catalyst. The highest total mass of 1,2,4-TriCB in the effluent and on the catalyst was 0.7 µg and 0.8 µg in dry and wet conditions, respectively. By calculating chorine mass balance, 35% of chlorine atoms do not present in the chlorinated compounds in the absence of water vapor. In comparsison, that value was 20% if the inlet gas stream contained water vapor. Therefore, steam can also impact the ability of the catalyst to destroy chlorinated compounds to Cl2. In terms of HeCB, there was a positive correlation between temperature and the catalytic adsorption capacity. There are currently not many scientific publications in this field, and more experiments are needed. |
