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采用阴离子交换树脂(AIER)为载体,以络合剂EDTA为媒介物,制备了Pd-Cu双金属负载性型催化剂;以H2为还原剂,将催化剂应用于水介质中NO3-还原为N2的脱除反应;考察了双金属催化剂组成、载体阴离子交换树脂的性质及水介质中NaCl存在对还原脱除反应的影响规律。研究结果表明,凭借阴离子交换树脂对EDTA强烈的吸附作用及EDTA对金属离子的强螯合作用,可将大量的金属离子(Cu2+与Pd2+)结合到树脂表面,再通过水合肼的还原作用,可制得金属负载量高且结合程度牢的双金属负载性型催化剂Pd-Cu/AIER。在单纯含有硝酸盐的水溶液中,在催化剂Pd-Cu/AIER的作用下,NO3-只能被还原为NH4+,不能还原为N2;水介质中大量氯离子的存在,能大大促进NO3-转变为N2的还原反应;载体阴离子交换树脂的碱性越弱,最终制得的催化剂活性与选择性越差。
Pd-Cu bimetallic supported catalysts were prepared by using anion-exchange resin (AIER) as carrier and complexing agent EDTA as catalyst. The catalyst was applied to the reduction of NO3- to N2 in aqueous media with H2 as reductant Removal of the reaction; investigated the bimetallic catalyst composition, the nature of the carrier anion exchange resin and NaCl in aqueous media on the impact of reduction reaction. The results show that with the strong adsorption of EDTA on EDTA and the strong chelation of EDTA to metal ions, a large amount of metal ions (Cu2 + and Pd2 +) can be bound to the surface of the resin. The reduction of hydrazine hydrate Pd-Cu / AIER catalysts with high metal loading and high bonding strength were prepared. Under the action of Pd-Cu / AIER, NO3- can only be reduced to NH4 + and can not be reduced to N2 under the simple aqueous solution of nitrate. The presence of a large amount of chloride in aqueous medium can greatly promote the conversion of NO3- to N2 reduction reaction; the weaker the basicity of the anion exchange resin of the carrier, the poorer the activity and selectivity of the catalyst finally obtained.