Development of catalytic system with nano-cluster catalyst for restoration of ground water polluted by nitrate

地下水被硝酸盐（NO_3^-）污染是一个普遍存在的问题，因为过量摄入硝酸盐会导致婴儿蓝婴综合症、糖尿病和癌症。主要来源是农业做法（肥料和牲畜排泄物），地下水的补救是一个紧迫的问题。生物处理、离子交换和反渗透仍存在许多问题。NO_3^-催化加氢制N_2是近年来研究的热点。在高pH值条件下，活性炭负载的Cu-Pd簇合物对NO_3^-的加氢反应具有很高的选择性。Pd交换β沸石催化NO_2 ~-选择性加氢为N_2和N_2O。从这些发现中，我们受到启发，在两个阶段的过程中，允许催化剂优化每个阶段; NO_3^-氢化 ...更多信息 第一段为NO_2 ~-还原反应，第二段为NO_2 ~-加氢反应。本文报道了Cu-Pd团簇/AC和Pd/β-沸石两段法净化水中硝酸盐的应用前景。值得强调的是，在298 K和288 K下，NH3浓度分别仅为0.7和0.6 ppm，非常接近允许值（0.5ppm）。然后使用单一催化剂针对饮用水的一步法，该催化剂具有可接受的活性、选择性，2wt%Pd-1.2wt%Cu/丝光沸石（Si/Al=37）对N_2和N_2O有很高的选择性，能抑制NH_3（从200 ppm的硝酸盐到5 ppm），在278-333 K范围内表现出稳定的稳定性。采用离子交换法制备了Cu-Pd/丝光沸石。近年来，由Pd-Cu簇合物制备的Pd-Cu/疏水活性炭催化剂表现出高活性和高选择性，即对氨的生成有很大的抑制作用。此外，该催化剂甚至在硫酸根离子和氯离子存在下也起作用。少

Pollution of groundwater with nitrate (NO_3^-) is a widespread problem, since excess intake of nitrate causes blue baby syndrome for infants and diabetes and cancers. The major sources are agricultural practices (fertilizers and excretions of livestock), and the remediation of groundwater is urgent issue. The biological treatment, ion exchange, and reverse osmosis have still much issues. Recently catalytic hydrogenation of NO_3^-to N_2 have attracted much attention. It is necessary to reduce the levels of harmful components to the maximum allowable levels, 50, 0.1-3, and 0.5 ppm for nitrate, nitrite (NO_2^-), and NH_3.We found that Cu-Pd clusters supported on active carbon are highly selective for the hydrogenation of NO_3^- to NO_2^- at high pH. On the other hand, Pd exchanged beta zeolite catalyzed selectively the hydrogenation of NO_2^- to N_2 and N_2O. From these findings, we were inspired in a two-stage process which allows catalysts optimized for each stage ; NO_3^-hydrogenation … More to NO_2^-in the first stage and NO_2^-hydrogenation in the second stage. Here we wish to report that the two-stage process consisting of Cu-Pd cluster/AC and Pd/beta-zeolite is promising for the purification of water contaminated nitrate. It should be emphasized that the concentration of NH_3 was only 0.7 and 0.6 ppm at 298 and 288 K, respectively which are very close to the allowable value (0.5 ppm) for drinking water.Then a one-stage process aimed at drinking water using a single catalyst, the catalyst with acceptable activity, selectivity, and stability for the practical use is searched 2wt%Pd-1.2wt%Cu/mordenite (Si/Al=37) was highly selective to N_2 and N_2O, depressing NH_3 (5 ppm from 200 ppm of nitrate) and exhibited robust stability at 278-333 K. Cu-Pd/mordenites that were prepared by ion-exchange method. Recently, Pd-Cu/hydrophobic AC catalysts prepared from Pd-Cu cluster exhibited was found to be high active and selective, that is, be greatly suppressed for the formation of ammonia. Furthermore, this catalyst has worked even in the presence of sulfated ion and chloride ion. Less