Fe-NaA分子筛膜的制备及催化湿式H_(2)O_(2)氧化甲基橙溶液

Preparation of Fe-NaA molecular sieve membrane and its application in catalytic wet peroxide oxidation of methyl orange solution

采用湿法造纸、二次生长和湿法浸渍法合成了一种新型微纤复合Fe-NaA分子筛膜催化剂,并将其用于催化湿式H2O2氧化甲基橙溶液.首先通过湿法造纸和烧结工艺制备纸状烧结不锈钢微纤(PSSF)载体,然后采用二次生长法在PSSF上合成NaA分子筛膜,最后以九水硝酸铁(Fe(NO3)3·9H2O)和微纤复合NaA分子筛膜为原料,利用湿法浸渍法制备微纤复合Fe-NaA分子筛膜催化剂.考察了连续固定床反应器中温度、床层高度、进料液流量和甲基橙入口浓度对甲基橙降解性能的影响,并测定了催化剂重复使用3次后的稳定性.结果表明,随温度及床层高度增加,甲基橙转化率先增加然后趋于稳定;随进料液流量增加,甲基橙转化率均大于95%,但COD脱除率略有降低,当流量分别为2、3和4mL·min^-1,固定床连续运转5h时COD脱除率分别为81.9%、76.4%和69.8%;随甲基橙入口浓度增加,其转化率变化幅度很小.在pH=2、催化剂床层高度2.0cm、温度70℃、进料液流量4mL·min^-1、甲基橙浓度50~200mg·L^-1、固定床连续运转5h的条件下,甲基橙转化率超过96%,COD转化率大于67%,铁浸出浓度低于4mg·L^-1.催化剂被重复使用3次后,甲基橙转化率基本保持不变.

A novel microfiber supported Fe?NaA molecular sieve membrane was prepared to catalyze wet peroxide oxidation of methyl orange in aqueous solution.Firstly,the paper?like sintered stainless steel fiber(PSSF)support was prepared by the wet lay?up papermaking and sintering process;then a NaA molecular sieve membrane was synthesized on the PSSF by secondary growth method;finally,microfiber supported Fe?NaA molecular sieve membrane catalyst was prepared by wet impregnation method using Fe(NO3)3·9H2O and NaA molecular sieve membrane as raw materials.The effects of temperature,bed height,influent flow rate and methyl orange concentration on the degradation performance were studied in a continuous fixed bed reactor filled with microfiber supported Fe?NaA molecular sieve membrane catalyst.The stability of the catalyst after three times of repeated use was determined.The results show that the removal of methyl orange first increased and then stabilized with the increase of temperature and bed height.The removal rate was greater than 95%with the increase of feed flow rate,but only a slight decrease in COD removal rates,which were 81.9%,76.4%and 69.8%at the feed flow rate of 2,3 and 4 mL·min^-1 in a continuous operation for 5 h.The methyl orange removal changed little with the increase of inlet methyl orange concentration.The methyl orange and COD removal rates were above 96%and 67%,respectively,and iron leaching concentration was below 4 mg·L^-1 under the conditions of bed height of 2.0 cm,pH 2,70℃,4 mL·min^-1 of feeding rate,and 50~200 mg·L^-1 of initial methyl orange concentration.After the catalyst was reused three times,the methyl orange removal rate remained almost unchanged.