Rapid removal of nitrate in water by hydrogenation to ammonia with Zr-modified porous Ni catalysts

Activated Carbon Supported Metal Catalysts for Nitrate and Nitrite Reduction in Water

“…Most of the work in the area of catalytic nitrate reduction has been done using Pd-Cu bimetallic catalysts; also Pd-Sn and Pt-Cu on different supports, mainly alumina, have been considered [1-4, 6-8, 17-19]. A few investigations have been reported for other metallic pairs [15,20,22,[28][29][30][31]. Therefore, we decided to study systematically the nitrate reduction in the presence of a larger set of bimetallic catalysts (Pd-Cu, PtCu, Rh-Cu, Ru-Cu, Pd-Ir, Pd-Sn, Pd-Fe, Pd-Ni, Pd-Zn, Ir-Cu, Rh-Sn, Pt-Sn and Pt-Fe) supported on activated carbon, with 1 wt% of each metal, in order to select the most promising systems.…”

Room‐Temperature Catalytic Reduction of Aqueous Nitrate to Ammonia with Ni Nanoparticles Immobilized on an Fe3O4@n‐SiO2@h‐SiO2–NH2 Support

“…In contrary to earlier reports that non‐noble‐metal catalysts are mostly inactive or poorly active for nitrate reduction to nitrogen compounds, the as‐synthesized Ni/M‐HMAF silica catalyst exhibits excellent catalytic activity (275 mmol g metal –1 h –1 ), which is higher than the most of the reported catalysts (Table S3). The higher activity for complete reduction of aqueous nitrate ions to ammonia at room temperature over the Ni/M‐HMAF silica catalyst is significant, as most of the earlier Ni‐based catalysts were either poorly active (hairy nickel foam: 0.096 mmol g metal –1 h –1 ) or need a promoter/activator to enhance the catalytic activity (Pt promoted Ni: 7.0 mmol g metal –1 h –1 and Zr‐modified porous Ni: 0.7 mmol g metal –1 h –1 ,, Table S3). Hence, through this work, we believe that a precisely designed and tuned non‐noble‐metal based catalyst has the potential to exhibit high catalytic performance for the reduction of nitrate ions in water, which has so far remained elusive.…”

“…Hence, for most of the non‐noble‐metal based catalysts, higher temperature/pressure or the presence of noble metals as a promoter or activator were found to be essential to enhance the activity of non‐noble‐metal catalysts for nitrate reduction . Okuhara et al reported Zr‐modified porous Ni catalysts for nitrate reduction to ammonia, where small amounts of Zr greatly enhance the activity of Ni by suppressing the oxidation of Ni 0 atoms (0.74 mmol g metal –1 h –1 ) . Later, they also reported a similar Pt‐promoted enhancement in the catalytic activity of Ni catalyst for the hydrogenation of nitrate and nitrite ions to ammonia at 60 °C (7.0 mmol g metal –1 h –1 ) .…”

“…Despite the fact that Ni‐based catalysts have shown excellent catalytic activity for the hydrogenation of nitro compounds to the corresponding amines,, the literature has revealed that non‐noble‐metals (for example, Ni) exhibit only poor activity for nitrate/nitrite reduction at room temperature . Hence, for most of the non‐noble‐metal based catalysts, higher temperature/pressure or the presence of noble metals as a promoter or activator were found to be essential to enhance the activity of non‐noble‐metal catalysts for nitrate reduction . Okuhara et al reported Zr‐modified porous Ni catalysts for nitrate reduction to ammonia, where small amounts of Zr greatly enhance the activity of Ni by suppressing the oxidation of Ni 0 atoms (0.74 mmol g metal –1 h –1 ) .…”

The abatement of major pollutants in air and water by environmental catalysis

“…For example, the nitrogen oxyanions are catalytically reduced to dinitrogen (N 2 ) and ammonia (NH 3 ). Beside these, other metals have also been developed for catalytic contaminant reduction, including supported Pt, Ir, Rh, Cu, Zn, Ru (alone or with a promoter metal), and various forms of Ni [272][273][274]. In general, Pdbased catalysts are more active, stable, and selective for desired end products, and/or less toxic.…”