Highly Selective Hydrogenation of Nitrate to Harmless Compounds in Water Over Copper–Palladium Bimetallic Clusters Supported on Active Carbon

Sakamoto, Y.; Kanno, Mitsuru; Okuhara, Toshio; Kamiya, Yuichi

doi:10.1007/s10562-008-9574-6

Cited by 22 publications

(15 citation statements)

References 18 publications

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“…On the other hand, if the ratio is low, the selectivity will be low. We have demonstrated that the selectivity for N 2 + N 2 O increases with a decrease in the partial pressure of H 2 over Cu-Pd bimetallic clusters supported on AC [14].…”

Section: Resultsmentioning

confidence: 91%

“…2) is a critical problem, because the allowable level of NH 3 in drinking water is 0.5 ppm. Many studies have been carried out on the catalytic reduction of NO 3 -using bimetallic catalysts, such as Cu-Pd [3][4][5][6][7][8][9][10][11][12][13][14], Sn-Pd [15][16][17], In-Pd [9,18], and Cu-Pt [19,20], since Vorlop and coworkers discovered that Cu-Pd/Al 2 O 3 is an active and selective catalyst [3,4]. [7].…”

Section: Introductionmentioning

confidence: 99%

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Remediation of actual groundwater polluted with nitrate by the catalytic reduction over copper–palladium supported on active carbon

Wang

Sakamoto

Kamiya

2009

Applied Catalysis A: General

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Catalytic reduction of nitrate (NO 3 -) in groundwater over a Cu-Pd catalyst supported on active carbon was investigated in a gas-liquid co-current flow system at 298 K. Although CuPd/active carbon, in which the Cu/Pd molar ratio was more than 0.66, showed high activity, high selectivity for the formation of N 2 and N 2 O (98%), and high durability for the reduction of 100 ppm NO 3 -in distilled water, the catalytic performance decreased during the reduction of NO 3 -in groundwater. The catalyst also irreversibly deactivated during the reaction in groundwater. The organic species in the groundwater caused the decrease in the catalytic performance and the irreversible catalyst deactivation. Ozone-treatment of the groundwater to remove the organic species substantially helped to maintain the catalytic activity and to halt the irreversible deactivation of the catalyst. Chloride ion (Cl -) in the groundwater also caused the decrease in the activity and selectivity, but the effects of Cl -were reversible. Sulfate ion (SO 4 2-) and cations, including Mg 2+ , Ca 2+ and K + , had little or no effect on the catalytic performance of Cu-Pd/active carbon, though they were present in the groundwater sample.More than an allowable level of NH 3 (NH 4 + ) was formed during the catalytic reduction of NO 3 -in the groundwater, but was completely removed by the cation-exchange process using Namordenite.3

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Section: Resultsmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Remediation of actual groundwater polluted with nitrate by the catalytic reduction over copper–palladium supported on active carbon

Wang

Sakamoto

Kamiya

2009

Applied Catalysis A: General

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“…The local concentrations of both NO 3 -and H 2 have been shown to be a key operating condition to maintain low levels of NH 3 during catalytic NO 3 -reduction [5, 9,18]. In an attempt to minimize NH 3 production, influent concentrations of 1.4 mM NO 3 -and 1.95 mM H 2 were used ( Fig.…”

Section: Hydrogen Concentrationmentioning

confidence: 99%

“…However, nitrate overload from anthropogenic sources can lead to contaminated drinking water in which the nitrate level exceeds the legal limit (USEPA MCL, 714 lM) [1]. The use of Pd-based heterogeneous catalysts with hydrogen as the electron donor has emerged as an attractive treatment strategy for nitrate-contaminated water [2], but the issues of selectivity (formation of significant amounts of ammonia as well as nitrogen) [2][3][4][5][6][7][8][9][10][11] and sustainability (activity maintenance when confronted with potential foulants in the source water) [10,11] remain formidable barriers to widespread adoption. We have examined how three critically important solution conditions affect the operation of a Pd-In/c-Al 2 O 3 catalyst for nitrate reduction: (i) the concentration of dissolved oxygen (DO), an alternative electron acceptor to nitrate, (ii) the specific NO 3 -:H 2 influent loading; and (iii) the presence of a known foulant, sulfide.…”

Section: Introductionmentioning

confidence: 99%

The Selectivity and Sustainability of a Pd–In/γ-Al2O3 Catalyst in a Packed-Bed Reactor: The Effect of Solution Composition

2009

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This study tested the selectivity and sustainability of an alumina-supported Pd-In bimetallic catalyst for nitrate reduction with H 2 in a continuous-flow packedbed reactor in the presence of: (i) dissolved oxygen (DO), an alternative electron acceptor to nitrate, (ii) variable NO 3 -:H 2 influent loadings, and (iii) the presence of a known foulant, sulfide. The sustainability of the catalyst was promising, as the catalyst was found to be stable under all conditions tested with respect to metal leaching. The presence of DO at concentrations typical of treatment conditions will increase H 2 demand for NO 3 -reduction, but has no negative impact on the selectivity of the catalyst. Under optimal conditions, i.e., a pH of 5.0 and a high NO 3 -:H 2 influent loading, low NH 3 selectivity (5%) was achieved for extended periods (36 days), resulting in sustained levels of NH 3 that approached the European legal limit. The biggest challenge to the sustainability of the catalyst was the addition of sulfide, that initially increased NH 3 selectivity and ultimately resulted in complete deactivation of the catalyst. Further work is required to identify regeneration methods to restore sulfide-fouled catalyst activity and selectivity; however, the most effective use would be to remove sulfide prior to catalytic treatment.

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“…However, they show high activity in the reduction of nitrites [3][4][5][12][13][14]. Among the studied bimetallic systems, palladium systems promoted with Cu, Sn, Ag or Fe supported on different kinds of oxide carriers [14][15][16][17][18][19][20], polymers [21,22], zeolites [23], active carbons [24][25][26], resin [27][28][29], showed the best catalytic characteristics. The mechanism of these systems has not been explained unequivocally yet.…”

Section: Introductionmentioning

confidence: 99%

The effect of support porosity on the selectivity of Pd–In/support catalysts in nitrate reduction

Krawczyk

Karski

Witońska

2011

Reac Kinet Mech Cat

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The influence of support porosity on the selectivity of home-made 5%Pd-2%In/support (support = SiO 2 , Al 2 O 3 , TiO 2 ) catalysts in nitrate reduction was studied. The main final products of the reaction were N 2 and NH 4? . Together with the decrease in pore diameter, an increase in ammonia concentration in the reaction mixture was observed. It is probably caused by slow diffusion of OH -ions from narrow pores to the solution.

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Highly Selective Hydrogenation of Nitrate to Harmless Compounds in Water Over Copper–Palladium Bimetallic Clusters Supported on Active Carbon

Cited by 22 publications

References 18 publications

Remediation of actual groundwater polluted with nitrate by the catalytic reduction over copper–palladium supported on active carbon

Remediation of actual groundwater polluted with nitrate by the catalytic reduction over copper–palladium supported on active carbon

The Selectivity and Sustainability of a Pd–In/γ-Al2O3 Catalyst in a Packed-Bed Reactor: The Effect of Solution Composition

The effect of support porosity on the selectivity of Pd–In/support catalysts in nitrate reduction

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