Chlor-Alkali Technologies

O’Brien, Thomas F.; Bommaraju, Tilak V.; Hine, Fumio

doi:10.1007/0-306-48624-5_5

Cited by 21 publications

(36 citation statements)

References 23 publications

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“…Faradaic efficiencies for Cl 2 production were determined to be 85% and 92% for the nSi/TiO 2 /Ir photoanode and the p+-Si/TiO 2 /Ir anode, respectively. Similar yields were determined using an Ir rod as the anode and also a dimensionally stable anode, comprising a film of RuO 2 /TiO 2 on a Ti foil 30 , and the slightly less than 100% Faradaic efficiencies for Cl 2 production for all these electrodes was attributed to a small degree of reaction of the very aggressively oxidising chlorine with the components of the system as it was swept from the electrochemical cell to the trap solution.…”

Section: Cl2 Yield and Stabilitysupporting

confidence: 60%

Silicon Photoanodes for Solar-Driven Oxidation of Brine: A Nanoscale, Photo-Active Analog of the Dimensionally-Stable Anode

Tang‐Kong

O’Rourke

Mills

et al. 2018

J. Electrochem. Soc.

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We report the first results in which ALD-TiO 2 layers electronically couple silicon to an overlying catalyst coating while inhibiting corrosion during brine splitting, a reaction that is capable of generating not only a fuel (H 2) but also a disinfectant (Cl 2 or NaOCl). An n-type silicon photoanode, and a p+-silicon anode are protected by a 1.7 nm coating of amorphous TiO 2 and 2 nm coating of Ir. The p+-Si/TiO 2 /Ir anode is able to effect the oxidation of chloride (0.5 M H 2 SO 4 , 3.5 M NaCl) in the dark with a low overpotential compared to that for oxidation of water (0.5 M H 2 SO 4). The 0.294 V overpotential difference occurs despite the difference in standard redox potentials, E = (E o (Cl 2 /Cl-)-E o (O 2 /H 2 O)), is 130 mV. Under 1 sun irradiation a photovoltage of ca. 0.566 V is achieved by comparing the illuminated n-Si/TiO 2 /Ir photoanode with the dark p+-silicon anode. Although the n-Si/TiO 2 /Ir photoanode is only one half of an eventual tandem cell needed for photosynthetic brine splitting, its ABPE for chloride oxidation is 1.42%, ca. 28 times that for water oxidation. The illuminated n-Si/TiO 2 /Ir photoanode remained stable at 1 mA cm-2 during a six-day chronopotentiometry test.

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Section: Cl2 Yield and Stabilitysupporting

confidence: 60%

Silicon Photoanodes for Solar-Driven Oxidation of Brine: A Nanoscale, Photo-Active Analog of the Dimensionally-Stable Anode

Tang‐Kong

O’Rourke

Mills

et al. 2018

J. Electrochem. Soc.

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“…We apply this approach to an important electrochemical reaction, chlorine evolution. This reaction is chosen for its industrial importance 25 and the complexities involved in mapping the selectivity with respect to oxygen evolution reaction. 26 Prior work by Hansen et al 5 shows that the overpotential for oxygen evolution to occur on rutile oxides, which involves three oxygen intermediates, is always higher than that for chlorine evolution.…”

Section: Introductionmentioning

confidence: 99%

Quantifying Confidence in DFT Predicted Surface Pourbaix Diagrams and Associated Reaction Pathways for Chlorine Evolution

2018

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Catalytic activity predictions and the identification of active sites rely on precisely determining the dominant reaction mechanism. The activity governing mechanism and products could vary with the catalyst material, which can be described by material descriptor(s), typically the binding strength(s) of key intermediate species. Density functional theory calculations can be used to identify dominant reaction mechanisms. However, the dominant reaction mechanism is sensitive to choice of the exchange correlation functional. Here, we demonstrate using the example case of chlorine evolution reaction on rutile oxides, which can occur through at least three reaction mechanisms each mediated by different surface intermediates and active sites. We utilize Bayesian error estimation capabilities within the BEEF-vdW exchange correlation (XC) functional to quantify the uncertainty associated with predictions of the operative reaction mechanism by systematically propagating the uncertainty originating from DFT-computed adsorption free energies. We construct surface Pourbaix diagrams based on the calculated adsorption free energies for rutile oxides of Ru, Ir, Ti, Pt, V, Sn and Rh. We utilize confidence-value (c-value) to determine the degree of confidence in the predicted surface phase diagrams. Using the scaling relations between the adsorption energies of intermediates we construct a generalized Pourbaix diagram showing the stable surface composition as a function of potential and the oxygen binding energy on the cus site (∆E O c ). This is used to consistently determine activity volcano relationships. We incorporate the uncertainty in linear scaling relations to quantify the confidence in generalized Pourbaix diagram and the associated activity. This allows us to compute the expectation limiting potential as a function of ∆E O c , which provides a more appropriate activity measure incorporating DFT uncertainty. We show that the confidence in the classification problem of identifying the active reaction mechanism is much better than the prediction problem of determining catalytic activity. We believe that such a systematic approach is needed for accurate determination of activities and reaction pathways for multi-electron electrochemical reactions such as N 2 and CO 2 reduction.

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“…Former mercury process sites show signs of soil contamination [25]. This was the most common technology, but its use declined in the later part of the 20th century [27]. As of 2011 the mercury process capacity has been below 10% of the international production capacity; the mercury cell is no longer produced or installed and there is a voluntary commitment by European manufacturers to phase out the use of the mercury cell process by 2020 [25].…”

Section: Health Issues With the Core Elements Of Vcm: Ethylene And Chmentioning

confidence: 99%

“…Up until the 21st century asbestos was a primary component of the diaphragm cell [27]. A closely woven steel screen covered with long fiber (chrysotile) asbestos and barium sulfate was used to separate the cells [27].…”

Section: Health Issues With the Core Elements Of Vcm: Ethylene And Chmentioning

confidence: 99%

Improving the Healthiness of Sustainable Construction: Example of Polyvinyl Chloride (PVC)

Petrović

Hamer

2018

Buildings

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Abstract:With the increasing emphasis on sustainable construction, it has become important to better understand the impacts of common materials. This is especially paramount with the introduction of the United Nations (UN) Sustainable Development Goals (SDGs) which call for more comprehensive evaluations, adding many aspects of social consideration to the issues of environmental sustainability, including human health. Polyvinyl chloride (PVC)/vinyl can be seen as a material with potential for significant adverse effects on a multiplicity of levels, and the construction industry is its single most significant consumer. This article presents a transdisciplinary review of adverse health impacts associated with PVC showing a number of issues: some that could be eliminated through design, but also some which appear inherent to the material itself and therefore unavoidable. The totality of issues revealed in relation to PVC presents a compelling case for a call for complete elimination of use of this material in sustainable construction.

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Chlor-Alkali Technologies

Cited by 21 publications

References 23 publications

Silicon Photoanodes for Solar-Driven Oxidation of Brine: A Nanoscale, Photo-Active Analog of the Dimensionally-Stable Anode

Silicon Photoanodes for Solar-Driven Oxidation of Brine: A Nanoscale, Photo-Active Analog of the Dimensionally-Stable Anode

Quantifying Confidence in DFT Predicted Surface Pourbaix Diagrams and Associated Reaction Pathways for Chlorine Evolution

Improving the Healthiness of Sustainable Construction: Example of Polyvinyl Chloride (PVC)

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