In-situ activated hydrogen evolution by molybdate addition to neutral and alkaline electrolytes

Gustavsson, John; Hummelgård, Christine; Bäckström, Joakim; Wallinder, Inger Odnevall; Rahman, Seikh Mohammed Habibur; Lindbergh, Göran; Eriksson, Sten; Cornell, Ann

doi:10.5599/jese.2012.0015

Cited by 9 publications

(40 citation statements)

References 23 publications

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“…Hypochlorite reduction is inhibited in all cases, but the low conducting films that are formed will also inhibit hydrogen evolution. Also, molybdates have successfully been tested in order to mimic the electrochemical film formation obtained for chromate ,. In this case, however, the film continues to grow, and the low conductivity of the oxide slows down the kinetics of the HER.…”

Section: Resultscontrasting

confidence: 48%

Understanding Selectivity in the Chlorate Process: A Step towards Efficient Hydrogen Production

Gomes

Busch²,

Wildlock

et al. 2018

ChemistrySelect

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Chlorate production is a highly energy demanding industrial process, where chlorate formation is accompanied with hydrogen formation on the cathode. To ensure a high cathodic current efficiency, sodium dichromate is added to the chlorate electrolyte to avoid reduction of hypochlorite formed as a reaction intermediate in the process. However, chromate is highly toxic to humans and environment, and therefore a replacement is desired. A model system with ex situ formed chromium oxide/hydroxide films were used to study hypochlorite reduction and hydrogen evolution. The experimental results demonstrate that the hypochlorite reduction is fully blocked while hydrogen evolution readily occurs. However, in the presence of hypochlorite the hydrogen evolution reaction is inhibited. By combining experimental findings with density functional theory (DFT) calculations, the mechanism of hypochlorite reduction was revealed and the reason for inhibition by the deposited chromium(III) film was demonstrated. Based on these results possible replacements for chromate are suggested.

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Section: Resultscontrasting

confidence: 48%

Understanding Selectivity in the Chlorate Process: A Step towards Efficient Hydrogen Production

Gomes

Busch²,

Wildlock

et al. 2018

ChemistrySelect

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“…No needle-like crystals were observed when examining the sample in the SEM and no phosphorous could be detected by EDS (not shown in Table 1). In an earlier publication we found that if phosphate was added to a Mo(VI)-containing electrolyte, no molybdenum containing films could be detected with EDS on the cathode surface [7]. In that case the phosphate concentration was 2.5-10 times higher than the molybdate concentration.…”

Section: Surface Analysis By Sem and Edsmentioning

confidence: 81%

“…Looking at the cathodic end of the graph an activation of hydrogen evolution about 300 mV is seen for the cases of 1 and 10 mM Mo(VI). As high Mo(VI) level as 100 mM did not give a similar decrease in overpotential, likely caused by resistive properties of the Mo(VI) film formed [7].…”

Section: Current Efficiency For Hydrogen Evolution In the Presence Ofmentioning

confidence: 91%

“…This seems true also for Mo(VI) addition and therefore it will be difficult to replace Cr(VI) in the existing process without replacing the steel cathodes with a more dimensionally stable material. We have earlier shown that Mo(VI) addition can activate a substrate so it will have a similar activity for HER as iron [7], thus less active materials can be used instead of iron/low alloyed carbon steel.…”

Section: Current Efficiency For Hydrogen Evolution At Low Chromate Comentioning

confidence: 99%

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On the suppression of cathodic hypochlorite reduction by electrolyte additions of molybdate and chromate ions

Gustavsson¹,

Li²,

Hummelgård³

et al. 2012

J. Electrochem. Sci. Eng.

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The goal of this study was to gain a better understanding of the feasibility of replacing Cr(VI) in the chlorate process by Mo(VI), focusing on the cathode reaction selectivity for hydrogen evolution on steel and titanium in a hypochlorite containing electrolyte. To evaluate the ability of Cr(VI) and Mo(VI) additions to hinder hypochlorite reduction, potential sweep experiments on rotating disc electrodes and cathodic current efficiency (CE) measurements on stationary electrodes were performed. Formed electrode films were investigated with scanning electron microscopy and energy-dispersive X-ray spectroscopy. Cathodic hypochlorite reduction is hindered by the Mo-containing films formed on the cathode surface after Mo(VI) addition to the electrolyte, but much less efficient compared to Cr(VI) addition. Very low levels of Cr(VI), in the mM range, can efficiently suppress hypochlorite reduction on polished titanium and steel. Phosphate does not negatively influence the CE in the presence of Cr(VI) or Mo(VI) but the Mo-containing cathode films become thinner if the electrolyte during the film build-up also contains phosphate. For a RuO2-TiO2 anode polarized in electrolyte with 40 mM Mo(VI), the anode potential increased and increased molybdenum levels were detected on the electrode surface.

QC 20130109

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“…The peaks at 2θ = 35 and 67.3 represent ɤ‐alumina, which corresponds to ZrO 2 –Al 2 O 3 (90:10) support . The peaks at 2θ = 38 and 44 correspond to nickel oxide in catalysts whereas peaks at 2θ = 23 and 25 correspond to molybdenum oxide in catalyst . The wide‐angle XRD pattern proves that nickel and molybdenum are incorporated on ZrO 2 –Al 2 O 3 support.…”

Section: Resultsmentioning

confidence: 92%

Catalytic hydrodeoxygenation of bio‐oil model compound for production of fuel grade oil

Patil

Lali

Dalai

2019

Asia-Pacific J Chem Eng

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Bio-oil, a promising renewable fuel candidate obtained from the hydrothermal liquefaction/pyrolysis of agricultural waste, contains significant amount of oxygen in the form of oxygenated compounds such as aldehydes, ketones, aliphatic/aromatic acids, alcohols, and ethers. This prevents it from being used directly as a fuel. Technologies that can lower the oxygen content of bio-oil are desired. The present work was driven towards the deoxygenation of bio-oil. To understand the mechanism of deoxygenation, guaiacol was selected as a model compound. The deoxygenating ability of acid site (support) and hydrogenation ability of metal were leveraged in this work. Highly acidic mixed oxide support such as ZrO 2 -Al 2 O 3 was used to synthesize a bimetal catalyst Ni-Mo/ZrO 2 -Al 2 O 3 , and the said catalyst was used for deoxygenation of bio-oil/model compound in tetralin as hydrogen donor solvent. The effects of reaction time, temperature, and hydrogen pressure on the conversion were examined. Results showed that 100% guaiacol conversion was obtained with 45.3% phenol and 11.1% cyclohexane yield at 330°C and 30-bar H 2 pressure and reaction time of 10 hr.Poly(ethylene oxide)-block-poly(propylene oxide)-block-(polyethylene oxide) (P123), zirconium propoxide (23−28% free alcohol), aluminum isopropoxide, diglycol, guaiacol, phenol, naphthalene, tetralin, cyclohexane, o-cresol, and p-cresol were all obtained from Sigma-Aldrich, Edmonton, Canada. Anhydrous ethanol, 70% nitric acid, and 30% aqueous ammonia were obtained from Fischer Scientific, Saskatoon, Canada.

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In-situ activated hydrogen evolution by molybdate addition to neutral and alkaline electrolytes

Cited by 9 publications

References 23 publications

Understanding Selectivity in the Chlorate Process: A Step towards Efficient Hydrogen Production

Understanding Selectivity in the Chlorate Process: A Step towards Efficient Hydrogen Production

On the suppression of cathodic hypochlorite reduction by electrolyte additions of molybdate and chromate ions

Catalytic hydrodeoxygenation of bio‐oil model compound for production of fuel grade oil

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