Highly N2-Selective Activated Carbon-Supported Pt-In Catalysts for the Reduction of Nitrites in Water

Abstract

The catalytic reduction of nitrites over Pt-In catalysts supported on activated carbon has been studied in a semi-batch reactor, at room temperature and atmospheric pressure, and using hydrogen as the reducing agent. The influence of the indium content on the activity and selectivity was evaluated. Monometallic Pt catalysts are very active for nitrite reduction, but the addition of up to 1 wt% of indium significantly increases the nitrogen selectivity from 0 to 96%. The decrease in the accessible noble metal surface area reduces the amount of hydrogen available at the catalyst surface, this favoring the combination of nitrogen-containing intermediate molecules to promote the formation of N2 instead of being deeply hydrogenated into NH4+. Several activated carbon-supported Pt-In catalysts, activated under different calcination and reduction temperatures, have been also evaluated in nitrite reduction. The catalyst calcined and reduced at 400°C showed the best performance considering both the activity and the selectivity to nitrogen. This enhanced selectivity is ascribed to the formation of Pt-In alloy. The electronic properties of Pt change upon alloy formation, as it is demonstrated by XPS.

Pd/In-based catalysts for nitrate catalytic removal from water: synthesis designs aiming for better N2 selectivity

“…Moreover, the addition of Pd and In in different steps represented a distribution of the particles on the surface in a way that favored the selectivity toward N 2 . In this sense, it is reasonable that the PIACR catalyst presented the lowest selectivity to N 2 since it showed good distribution of Pd and In on the support surface, and generally, the selectivity to N 2 was higher for catalysts with lower dispersion (Yoshinaga et al 2002;Garron et al 2005;Zhang et al 2008;Soares et al 2021).…”

“…These factors, in turn, depend on the preparation method and the metal loading (Martínez et al 2017). On the other hand, Pd particle size considerably affects the selectivity to N 2 , with better selectivity being obtained in the presence of metallic agglomerates (Yoshinaga et al 2002;Garron et al 2005;Zhang et al 2008;Soares et al 2021). Marchesini et al (2008) and Zhang et al (2008) found that selectivity was greatly correlated to the size of active metal particles.…”

Fabrication of a Disposable Amperometric Sensor for the Determination of Nitrite in Food

“…Nitrite is a common chromogenic agent and preservative in meat food because it can not only make the color of meat look better, but also inhibit the generation of botulinum toxin [ 1 ]. However, the excessive intake of nitrite will lead to methemoglobinemia [ 2 ] and gastric cancer [ 3 ]. Therefore, monitoring whether the amount of nitrite in food is excessive is essential to protect human health, requiring the accurate and timely monitoring of nitrite in food samples.…”

Mussel-Inspired Magnetic Dissolving Pulp Fibers Toward the Adsorption and Degradation of Organic Dyes

“…Adsorption is one of the most effective methods to treat organic dyes, and it is widely used because of its relatively low cost and easy operation. Various adsorbents have been designed to remove dyes in water and have considerable adsorption capacities, such as activated carbon ( Tang et al, 2017 ; Zhang et al, 2019 ; Soares et al, 2021 ), functional carbon materials ( Magno et al, 2020 ; Xing et al, 2020 ; Zhang et al, 2020 ), composite hydrogel ( Srivastava and Roy Choudhury, 2021 ), and metal oxide ( Rastogi et al, 2017 ; Xu et al, 2020 ; Şerban and Enesca, 2020 ). Among these methods, chemistry reduction has gained popularity because of its ease of use, high efficiency, clean processing, and low cost.…”