Kinetics of formation at 800°C of ‘Cu<sub>2</sub>S’ on copper under gases containing H<sub>2</sub>S

Sick, Georg; Schwerdtfeger, Klaus

doi:10.1179/mst.1986.2.2.159

Cited by 5 publications

(4 citation statements)

References 13 publications

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“…The reduction and sulfidation equilibria of CuO are well established. 8,9,37,38 CuO is readily reduced to the metal state, while Cu 2 O exists only when the partial pressure of oxygen exceeds 10 -10 atm at 1000 K. The sulfidation product of copper is cuprous sulfide, Cu 2 S, under the experimental conditions used here. The Cu-O-S phase diagram was included in a recent paper.…”

Section: Resultsmentioning

confidence: 90%

Reduction and Sulfidation Kinetics of Cerium Oxide and Cu-Modified Cerium Oxide

Kobayashi

Flytzani‐Stephanopoulos

2002

Ind. Eng. Chem. Res.

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The reducibility and H2S absorption capacity of cerium oxide and Cu-containing cerium oxide were examined in this work in the temperature range 623−923 K. The sorbents, prepared in bulk oxide form by the urea coprecipitation/gelation method, were composed of a cerium oxide backbone with a small amount of copper (5−40 atom %). Kinetics testing was conducted in a TGA apparatus. Temperature-programmed-reduction (TPR) experiments and in situ X-ray diffraction analysis were used to determine the reduction temperature and the various metal/oxide crystal phases. CuO in ceria was reduced to Cu metal at temperatures below 453 K. The reducibility of cerium oxide was increased by the presence of copper. A low Cu content (5 atom %) was sufficient to cause surface reduction of ceria at a temperature as low as 423 K. Sulfidation of prereduced samples was performed at 0.1 MPa in H2S−H2−N2 gas mixtures. The contribution of reduced cerium oxide to sulfidation was evident even at the low temperature 623 K. Thus, copper promotes both the reducibility and sulfidation of cerium oxide. The activation energy of the sulfidation reaction was calculated from initial sulfidation reaction rates over the temperature range 623−923 K. A low apparent activation energy of 16 ± 3 kJ/mol was found for the Cu contents 5 and 15 atom % in ceria, while the activation energy is 34 kJ/mol for the 40 atom % Cu−CeO x sorbent. This work has shown that copper-modified cerium oxide can be used as a sulfur sorbent over a wide temperature window.

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Section: Resultsmentioning

confidence: 90%

Reduction and Sulfidation Kinetics of Cerium Oxide and Cu-Modified Cerium Oxide

Kobayashi

Flytzani‐Stephanopoulos

2002

Ind. Eng. Chem. Res.

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“…It is therefore likely that the "layer" of Cu2S that is formed through much of the first stage of reaction has cracks (see Sick and Schwerdtfeger, 1986) through which H2S(g) has sufficiently direct access to the metallic surface that the reaction rate is not diffusion controlled until the average thickness of the Cu2S is quite large. In the first stage, the rate of reaction is controlled by the surface reaction and is dependent on the surface area of copper but not (except at very low pressures) on the pressure or concentration of H2S.…”

Section: Discussionmentioning

confidence: 99%

“…The rate of the second stage of reaction is determined by the thickness of the accumulating layer of As shown by the differences in densities, there is a considerable volume change when Cu is converted to Cu2S. It is therefore likely that the "layer" of Cu2S that is formed through much of the first stage of reaction has cracks (see Sick and Schwerdtfeger, 1986) through which H2S(g) has sufficiently direct access to the metallic surface that the reaction rate is not diffusion controlled until the average thickness of the Cu2S is quite large. After the reaction does become diffusion controlled in the second stage, we are unable to distinguish between diffusion through "bulk" Cu2S or diffusion of H2S through tiny cracks in the relatively thick Cu2S phase.…”

Section: Discussionmentioning

confidence: 99%

“…Several earlier researchers, including Czanderna et al (1980), Franey et al (1982), Bartkowicz and Stoklosa (1985), Sick and Schwerdtfeger (1986), and Kyotani et al (1989) have investigated kinetics of formation of copper sulfide, but these earlier investigations were carried out under conditions (higher or lower temperature, different composition of gas phase, or elemental sulfur as sulfurizing agent) that are different from the conditions that are pertinent to our interest in obtaining H2 from H2S. …”

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confidence: 99%

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Kinetics of desulfurization of hydrogen sulfide using metallic copper as a desulfurizer

Chen

Hepler

1991

Can J Chem Eng

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The kinetics of desulfurization of hydrogen sulfide, using metallic copper as desulfurizer, have been investigated over a range of temperatures and pressures of hydrogen sulfide. Our results indicate that there are two stages of reaction; activation energies for the first and second stages are 63 kJ/mol and 38 kJ/mol, respectively. Possible reaction mechanisms in which the initial rate is controlled by interface reaction and the later stage is controlled by diffusion through or in the Cu,S layer are consistent with the experimental data. ~~~ ~_ _On a 6tudiC la cinCtique de desulfuration de I'hydrogkne sulfur6 avec du cuivre mktallique comme agent de dksulfuration dans une gamme de temperatures et de pressions d'hydrogkne sulfur& Les resultats indiquent qu'il y a deux Ctapes de reaction: les energies d'activation pour les premikre et deuxikme Ctapes sont de 63 kJ/mol et de 38 kJ/mol, respectivement. Les mtcanismes de rkaction possibles, dans lesquels la vitesse initiale est contrBlCe par la rtaction a l'interface et 1'Ctape ultkrieure par la diffusion a travers ou dans la couche de Cu,S, concordent avec les donnees experimentales.

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