低温降解二氯甲烷的TiO_2－SO_4^（2－）催化剂研究

Low Temperature Catalytic Decomposition of Methylene Chloride on Sulfated Titania Catalyst

研制了硫酸化氧化钛催化剂（表示为ＴｉＯ_２－ＳＯ_４^（２－）），实验表明在低于３００℃的反应温度下，它能有效地降解二氯甲烷（浓度为４２．８μｍｏｌ／Ｌ），如在２７５℃，二氯甲烷的转化率达１００％，降解产物为ＣＯ、ＣＯ_２和ＨＣｌ．该催化剂含２％硫酸根，氨的吸附量为每克催化剂３．４ｍｍｏｌ．与未经硫酸化处理的ＴｉＯ_２对比，硫酸化后的催化活性显著提高，表明二氯甲烷降解反应发生在固体酸的酸性活性中心上．水汽的存在明显降低了催化活性，提高了反应活化能．在ＴｉＯ_２－ＳＯ_４^（２－）上负载ＣｕＯ后可显著提高降解产物中二氧化碳的选择性．

It was found that the sulfated titania catalyst is very effective in the catalytic decomposition of methylene chloride by air below 300℃. Methlene chloride with concentration of 42.8 μmol/L in air can be converted selectively to CO, CO2and HCI. The catalyst contains about 2% by weight of sulphate ion , and has a uptake of 3. 4 mmole NH3. The results revealed that the acidic property of TiO2- catalyst is the determing factor for catalytic activity in methylene chloride decomposition. Addition of water vapor to the feed remarkably reduces the catalytic activity. The possible reason could be the bolckage of acidic sites on the surface of catalyst by water molecules. The selectivity to carbon dioxide could be improved by supporting copper oxide on sulfated titania, which indicated that copper oxide can promote the deep oxidation of methylene chloride.