Hydrolysis of molten CaCl&lt;sub&gt;2&lt;/sub&gt;-CaF&lt;sub&gt;2&lt;/sub&gt; with additions of CaO

Olsen, Espen; Hansen, Maria; Nygård, Heidi S.

doi:10.3934/energy.2017.6.873

Cited by 14 publications

(10 citation statements)

References 17 publications

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“…The third part of the corrosion test included the addition of ZnO, which is supposed to suppress hydrolysis reactions of the molten salt (e.g., analyzed in previous studies [ 16,17 ] ), thereby reducing its potential corrosivity toward the containment materials. The microstructures of all three alloys exposed to the threefold system are shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

“…The addition of ZnO is likely to reduce the evolution and corrosion reactions of the formed HCl gas. Olsen [ 16 ] and later Niazi [ 17 ] proposed, respectively, that metal oxides of Ca and Zn can reduce the formation of HCl gas, thereby reducing the corrosive nature of the molten halide salts. In our study, we assume that ZnO captures evolving HCl gas according to the following reaction.

ZnO + 2 HCl ⇌ {ZnCl}_{2} + {normalH}_{2} O ↑

…”

Section: Resultsmentioning

confidence: 99%

“…In a similar fashion, the addition of solid oxides (e.g., ZnO and CaO) leads to a significant reduction of hydrolysis reactions of the respective chloride salts, ZnCl 2 and CaCl 2 . [ 16,17 ] This is attributed to the fact that the oxides are able to react with HCl formed during hydrolysis and react back to the respective chlorides according to

MO + 2 HCl \to {MCl}_{2} + {normalH}_{2} O

where M is the metal cation (e.g., Zn or Ca). By adding inhibiting metal oxides to a molten salt, the molten salt's corrosivity can be reduced, thereby prolonging the lifetime of the reactor system.…”

Section: Introductionmentioning

confidence: 99%

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Synthetic Biofuels by Molten‐Salt Catalytic Conversion: Corrosion of Structural Materials in Ternary Molten Chlorides

et al. 2022

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The molten‐salt catalytic conversion of biomass into synthetic fuels is one of the promising renewable energy topics of the 21st century. Mixtures of Zn–Na–K//Cl have gained attention, acting as catalytically active heat transfer fluids in the conversion process, due to their low costs and principally low melting points which effectively lower the required operating temperature in the catalytic reactor. Herein, the corrosion behavior of three candidate steels, SS316L, SS321, and Alloy 800, in the pure molten salt, in a salt–biomass mix, and in a salt–biomass mix containing a corrosion inhibitor (zinc oxide (ZnO)) is comprehensively investigated. The herein described study demonstrates that biomass additions increase the penetration depth of the salt, and the corrosion mechanism leads to partial spalling of the oxide scale. This is attributed to the presence of oxygen and moisture from the biomass leading to the formation of reactive HCl gas. The addition of ZnO reduced the corrosivity of the molten salt–biomass mix, and all alloys obtained a protective, adherent, and thin oxide scale leading to the conclusion that ZnO indeed is an effective corrosion inhibitor for the presented salt system. These findings constitute a major advance in the implementation of molten salt‐catalytic reactors for renewable synthetic fuel production.

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Section: Resultsmentioning

confidence: 99%

ZnO + 2 HCl ⇌ {ZnCl}_{2} + {normalH}_{2} O ↑

…”

Section: Resultsmentioning

confidence: 99%

MO + 2 HCl \to {MCl}_{2} + {normalH}_{2} O

Section: Introductionmentioning

confidence: 99%

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Synthetic Biofuels by Molten‐Salt Catalytic Conversion: Corrosion of Structural Materials in Ternary Molten Chlorides

et al. 2022

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“…Calcium Chloride (CaCl 2 ). Olsen et al 58 studied the effect of lime (CaO) addition on the pyrohydrolysis of a eutectic of CaCl 2 and CaF 2 (81.5 versus 18.5 mol %) exposed to inert nitrogen (N 2 ) blended with 10 vol % steam, at the experimental temperatures ranging from 660 to 1000 °C. As shown in Figure 2, the CaO addition suppresses the release of HCl and HF from CaCl 2 and CaF 2 , respectively, irrespective of the reaction temperature.…”

Section: ■ Chlorine Release Difference Between Organic and Inorganic ...mentioning

confidence: 99%

Critical Review on the Chemical Reaction Pathways Underpinning the Primary Decomposition Behavior of Chlorine-Bearing Compounds under Simulated Municipal Solid Waste Incineration Conditions

2019

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Incineration has been proven as one of the most viable and efficient waste-to-energy strategies for the handling of rapidly mounting municipal solid waste (MSW). However, as a generic and key element in MSW, chlorine (Cl) brings about severe corrosion in boilers and the presence of Cl-containing species induces the release of toxic dioxins and furans by acting as chlorine donors. The chlorine release behavior from MSW during incineration has thus drawn plenty of attention. This paper has critically reviewed the origin of different chlorine-bearing species in MSW and their respective thermal decomposition behavior. In general, chlorine in MSW has two primary sources: plastics, mainly polyvinyl chloride (PVC), as the source of organic chlorine and household kitchen and garden waste as the source of inorganic chlorine, mainly chlorides. Distinct chlorine liberation properties have been observed for these two different chlorine groups. Chlorine in PVC converts to HCl gas easily at 300 °C as a result of the thermal decomposition combined with a depolymerization of the polymer chain. In contrast, the release of chlorine from inorganic chloride salts is much lower than that from PVC, mainly attributing to either strong volatilization properties of alkali chlorides (NaCl and KCl) or the high ionic bonding energies between some cations, such as Ca2+/Ni2+ and Cl–. Meanwhile, the decomposition of FeCl2, CoCl2, and MgCl2 is easier with the onset temperature for HCl release being around 180, 300, and 415 °C, respectively. Additionally, the addition of SO2, O2, or acidic solids (such as SiO2 and Al2O3) has been found to promote the chlorine release from chlorides appreciably. However, the exploitation of the underpinning mechanism is far from completion, especially for CaCl2 and CoCl2. This requests extra and intensive studies to elucidate the chlorine liberation mechanism from these inorganic species, even from the molecular level in terms of their ionic bonding propensity and breakage at high temperatures.

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“…This echoes the low-emission oxy-fuel combustion process in the power generation systems. [15] Instead of air, the CO 2 -dominant gas is injected into a pyrohydrolyser to generate an outlet gas stream primarily consisting of CO 2 , steam, and HCl. Through a subsequent condensation, an HCl acid at near-/ super-azeotropic concentration is desired, whereas the remaining dry gas is supposed to be highly rich in CO 2 and ready for utilization or sequestration.…”

Section: Introductionmentioning

confidence: 99%

Can CO₂ and Steam React in the Absence of Electrolysis at High Temperatures?

et al. 2020

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The fundamental question of whether CO2 can react with steam at high temperatures in the absence of electrolysis or high pressures is answered. These two gases are commonly co‐present as industrial wastes. Herein, a simple experiment by flowing CO2 and steam through a CaCl2 matrix at 500–1000 °C and atmospheric pressure was designed. Comprehensive characterizations and density functional theory calculations were conducted. Meanwhile, this study aims to recover HCl from CaCl2 via a low‐emission oxy‐pyrohydrolysis process. As confirmed, CO2 and steam interact strongly on the CaCl2 surface, leading to an explicit formation of CaCO3/CaO and a nearly complete release of HCl. This is mainly contributed to a halved energy required for the splitting of H2O, resulting from the formation of a bicarbonate‐like structure to replace Cl− out of CaCl2, an otherwise industrial waste, whilst an important dopant for carbon capture, utilization and storage, and medium for electrochemical synthesis.

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Hydrolysis of molten CaCl<sub>2</sub>-CaF<sub>2</sub> with additions of CaO

Cited by 14 publications

References 17 publications

Synthetic Biofuels by Molten‐Salt Catalytic Conversion: Corrosion of Structural Materials in Ternary Molten Chlorides

Synthetic Biofuels by Molten‐Salt Catalytic Conversion: Corrosion of Structural Materials in Ternary Molten Chlorides

Critical Review on the Chemical Reaction Pathways Underpinning the Primary Decomposition Behavior of Chlorine-Bearing Compounds under Simulated Municipal Solid Waste Incineration Conditions

Can CO₂ and Steam React in the Absence of Electrolysis at High Temperatures?

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Hydrolysis of molten CaCl<sub>2</sub>-CaF<sub>2</sub> with additions of CaO

Cited by 14 publications

References 17 publications

Synthetic Biofuels by Molten‐Salt Catalytic Conversion: Corrosion of Structural Materials in Ternary Molten Chlorides

Synthetic Biofuels by Molten‐Salt Catalytic Conversion: Corrosion of Structural Materials in Ternary Molten Chlorides

Critical Review on the Chemical Reaction Pathways Underpinning the Primary Decomposition Behavior of Chlorine-Bearing Compounds under Simulated Municipal Solid Waste Incineration Conditions

Can CO2 and Steam React in the Absence of Electrolysis at High Temperatures?

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Can CO₂ and Steam React in the Absence of Electrolysis at High Temperatures?