Catalytic bromate reduction in water: Influence of carbon support

Soares, O.S.G.P.; Ramalho, P. S. F.; Fernandes, Ana; Órfão, J.J.M.; Pereira, M.F.R.

doi:10.1016/j.jece.2019.103015

Cited by 24 publications

(33 citation statements)

References 45 publications

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“…For this reason, the use of a milled support is able to obtain enhanced catalytic results. Soares et al [41] reported that the ball mill technique applied on the carbon nanotubes promoted textural modifications, mainly related to the disentanglement of the tubes, which leads to a consequent increase in the specific surface area of the materials, and consequently enhances the activity of the catalyst; in this same work, milled carbon nanotubes were used as support for Pd and Pd-Cu complexes and applied for bromate conversion. Promising results were obtained for the modified carbon nanotubes, attributing their efficiency to the higher accessibility of the ionic species, present in water, to the support surface due to less entanglement of the tubes, which is a characteristic of the milled materials.…”

Section: Effect Of the Supportmentioning

confidence: 90%

“…The use of this support enhanced the catalytic activity, mainly in terms of reaction rate, achieving complete conversion in 180 min. Previous works, regarding bromate catalytic reduction in the presence of monometallic catalyst supported on modified carbon nanotubes, reported that the modifications performed on CNTs, through ball mill treatment, allowed an increase in the catalytic activity of the material, pointing to the increase in the specific surface area of the support and the disentangling of the tubes as the main causes for this result [34,41]. However, nitrite and ammonium concentrations at the end of the reaction are still a problem since their values are still above the imposed legal limits.…”

Section: Effect Of the Supportmentioning

confidence: 99%

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Nitrate Catalytic Reduction over Bimetallic Catalysts: Catalyst Optimization

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et al. 2020

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The catalytic removal of nitrate (NO3−) in water using hydrogen as a reducing agent was studied using palladium-copper bimetallic catalysts in different supports. Commercial carbon nanotubes (CNTs), used as received and with different mechanical (CNT (BM 2h)) and chemical modifications (CNT (BM 4h)-N), titanium dioxide (TiO2) and composite materials (TiO2-CNT) were considered as main supports for the metallic phase. Different metal loadings were studied to synthesize an optimized catalyst with high NO3− conversion rate and considerable selectivity for N2 formation. Among all the studied support materials, the milled carbon nanotubes (sample CNT (BM 2h) was the support that showed the most promising results using 1%Pd-1%Cu as metallic phases. The most active catalysts were 2.5%Pd-2.5%Cu and 5%Pd-2.5%Cu supported on CNT (BM 2h), achieving total conversion after a 120 min reaction with N2 selectivity values of 62% and 60%, respectively. Reutilization experiments allowed us to conclude that these catalysts were stable during several reactions, in terms of NO3− conversion rate. However, the consecutive reuse of the catalyst leads to major changes concerning NH4+ selectivity values.

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Section: Effect Of the Supportmentioning

confidence: 90%

Section: Effect Of the Supportmentioning

confidence: 99%

Nitrate Catalytic Reduction over Bimetallic Catalysts: Catalyst Optimization

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Restivo

Orge

et al. 2020

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“…Incipient wetness impregnation was used for Pd incorporation in CF supports, wherein the noble metal was dispersed on the surface of CFs. The procedure used was adapted from previous works [38,51] using CF1 and CF2 as supports. Firstly, CF1 and CF2 were ground to a controlled particle diameter between 0.1 and 0.3 mm and placed under ultrasonic mixing.…”

Section: Preparation Of Pd/cfs By Incipient Wetness Impregnation Methodsmentioning

confidence: 99%

“…AC as a support could also contribute to bromate removal by adsorption. Soares et al [51] demonstrated the influence of chemical and textural surface properties of the catalyst support using as-received and modified MWCNT, wherein N-doped MWCNTs were the best support, while acid samples presented the worst performances, since electrostatic interactions with BrO 3 − were enhanced in the presence of basic supports. Nanocarbon fibers (CFs) have been achieving promising results when used as a support for noble metals in catalytic BrO 3…”

Section: Bromate (Bromentioning

confidence: 99%

Palladium Impregnation on Electrospun Carbon Fibers for Catalytic Reduction of Bromate in Water

et al. 2022

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The remediation of bromate in water is a concern due to the reported health issues caused by its ingestion. Catalytic processes, wherein bromate is reduced to non-hazardous bromide, have been studied. In the present work, catalysts of 1% palladium supported in electrospun carbon fibers (Pd-CFs) using different methods for palladium incorporation were prepared. The textural properties, morphology, crystalline structure, and hydrogenation capacity by H2 chemisorption analysis of the Pd-CFs catalysts were characterized. The catalytic tests were performed in a semi-batch reactor, and the obtained results showed different catalytic activity by each prepared Pd-CFs catalyst. The catalysts prepared by incipient wetness impregnation—1% Pd/CF1 and 1% Pd/CF2, using CFs obtained with electrospinning flow rates of 0.5 mL h−1 and 2 mL h−1, respectively—achieved total bromate reduction after 120 min of operation; however, 1% Pd/CF1 obtained total reduction as early as 30 min. Taking into account the catalyst properties, 1% Pd/CF1 showed a good catalytic activity due to CFs morphology obtained using a low electrospinning flow rate, while the Pd incorporation method allowed a high availability of active sites with hydrogenation properties for bromate reduction.

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“…Recently new papers have described the use in this reaction of mono and bimetallic catalysts supported on activated carbon, titania and zeolites, obtaining interesting results [27–34] . The authors have proposed a mechanism for the bromate reduction involving reactions in the liquid phase and on the surface of the catalyst [29] .…”

Section: Introductionmentioning

confidence: 99%

The Influence of the Support Nature and the Metal Precursor in the Activity of Pd‐based Catalysts for the Bromate Reduction Reaction

et al. 2021

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Palladium catalysts supported on different materials (alumina, activated carbon and mixed oxide derived from hydrotalcite) and prepared with different metal precursors (nitrate, chloride and acetate) have been characterized and tested for the bromate reduction reaction. The catalytic behavior depends on the support nature and on the metallic precursor used for the catalyst preparation. Pd catalyst supported on a mixed oxide has a low activity due to the high affinity of the reconstructed support for the Br− formed, preventing the reactants to approximate the active Pd sites. Pd catalyst supported on activated carbon has a surface negative charge and a microporous structure, making difficult the interaction of the active sites with the reactants. The best results are obtained with the catalyst supported on alumina due to its physical‐chemical properties, i. e. mesoporosity, positive surface charge and reversible adsorption of reactants and products. These characteristics make easy bromate and H2 adsorption on the active sites and subsequent reaction, thus resulting in a better activity. The Pd precursor salt also influences the catalytic activity as it has an effect on the Pd nanocrystal size. The best results are obtained with the metal precursor that produces homogeneous and large Pd metallic crystallites.

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Catalytic bromate reduction in water: Influence of carbon support

Cited by 24 publications

References 45 publications

Nitrate Catalytic Reduction over Bimetallic Catalysts: Catalyst Optimization

Nitrate Catalytic Reduction over Bimetallic Catalysts: Catalyst Optimization

Palladium Impregnation on Electrospun Carbon Fibers for Catalytic Reduction of Bromate in Water

The Influence of the Support Nature and the Metal Precursor in the Activity of Pd‐based Catalysts for the Bromate Reduction Reaction

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