Cu/Al改性MCM-41分子筛催化剂的原位制备及其除氧性能

IN-SITU PREPARATION OF Cu / Al MODIFIED MCM-41 MOLECULAR SIEVECATALYST AND ITS DEOXYGENATION PERFORMANCE

利用一步水热合成法制备了Cu、Al改性的Cu/Al-MCM-41分子筛催化剂,用于再生水中DO的脱除,考察了活性金属添加量、催化剂制备pH、晶化温度和晶化时间对DO去除率的影响。结果表明:在n(Cu)/n(Si)、n(Al)/n(Si)分别为0.2、0.1,pH=10.5,140℃下晶化36 h,制得的Cu/Al-MCM-41在反应60 min后对再生水中DO的去除率可达到97.0%。同时,再生水与模拟水的水质对DO去除效果的影响较小。碳酰肼在Cu/Al-MCM-41的催化作用下被二次分解成为N_(2)和4个氢原子(H·),催化剂表面吸附H·浓度的增加使得DO被快速还原,且Cu、Al的引入明显增加了酸性位点的数量,使得催化剂的总酸性增强,促使DO分解产生氧化性更强的羟基自由基(·OH),与具有较高的活性和还原性的H·结合生成水,加速了DO的去除。

Cu/Al-MCM-41 molecular sieve catalyst modified by Cu and Al was prepared by a one-step hydrothermal synthesis method for desolved oxygen(DO)removal in reclaimed water.The effects of the adding amount of active metal,pH of catalyst preparation,crystallization temperature and crystallization time on the removal rate of DO were investigated.The results revealed that when the molar ratio of Cu/Si and Al/Si were 0.2 and 0.1,respectively,pH was 10.5,and Cu/Al-MCM-41 was crystallized at 140℃for 36 hours,the removal rate of DO in reclaimed water reached 97.0%after 60 min.Meanwhile,the quality of reclaimed water and simulated water had little influence on the DO removal effect.Carbohydrazide was secondary decomposed into N_(2) and four hydrogen atoms(H·),under the catalysis of Cu/Al-MCM-41.The increase in the concentration of hydrogen atoms adsorbed on the catalyst surface led to the rapid reduction of DO concentration.The introduction of Cu and Al could significantly increase the acidic sites and enhance the total acidity of catalysts to promote the decomposition of DO,to generate more oxidizing hydroxyl radicals(·OH),which can combine with hydrogen atoms with higher activity and reducibility to form H2O.This speeds up the removal of dissolved oxygen.