Mechanistic features of reduction of copper chromite and state of absorbed hydrogen in the structure of reduced copper chromite

Хасин, А. В.; Yur'eva, T. M.; Plyasova, L. M.; Kustova, G. N.; Jobic, H.; Ivanov, A. Yu.; Chesalov, Yu. A.; Zaikovskii, V. I.; Davydova, L. P.; Parmon, Valentin N.

doi:10.1134/s1070363208110418

Cited by 16 publications

(8 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The reduction of copper-chromite catalysts through the substitution of copper cations by the protons in the spinel structure does not destroy this structure 17 . Extension of the reduction time of CuCr 2 O 4 P catalyst over the time period 0-24 h decreases the selectivity of transformation to: methane, methanol, ethylene glycol, 1-and 2-propanol (Table 4).…”

Section: Resultsmentioning

confidence: 99%

Influence of reduction time of copper based catalysts: Cu/Al₂O₃ and CuCr₂O₄ on hydrogenolysis of glycerol

Wołosiak‐Hnat

Milchert

Lewandowski

et al. 2011

Polish Journal of Chemical Technology

View full text Add to dashboard Cite

High activity of copper based catalysts for C-O bond hydro-dehydrogenation and their poor activity for C-C bond cleavage1 have prompted an attempt to apply such catalysts in the hydrogenolysis of glycerol to 1,2-and 1,3-propanediol. In the present study the infl uence of hydrogen reduction time of the Cu/ Al 2 O 3 and CuCr 2 O 4 copper catalysts on glycerol conversion and selectivity of transformation to propanediols and by-products was studied. At fi rst a general comparison was made between the commercial catalysts and those prepared by the co-precipitation method. As better results were obtained in the presence of catalysts prepared by co-precipitation, they were selected for further detailed studies of the infl uence of reduction time. For both prepared catalysts Cu/Al 2 O 3 and CuCr 2 O 4 the reduction time of 8 h was optimal. In the presence of Cu/Al 2 O 3 catalyst the conversion of glycerol was 59.0%, selectivity of transformation to 1,2-propanediol 77.4% and selectivity to 1,3-propanediol 1.9%. In the presence of CuCr 2 O 4 the glycerol conversion was 30.3% and selectivity to 1,2-propanediol 67.3%.

show abstract

Section: Resultsmentioning

confidence: 99%

Influence of reduction time of copper based catalysts: Cu/Al₂O₃ and CuCr₂O₄ on hydrogenolysis of glycerol

Wołosiak‐Hnat

Milchert

Lewandowski

et al. 2011

Polish Journal of Chemical Technology

View full text Add to dashboard Cite

show abstract

“…The studies of copper chromite reduction by inelastic neutron scattering, Raman spectroscopy, and temperatureprogrammed reduction [93] confirmed that copper chromite is an oxide system that can oxidize hydrogen and accumulate protons in its structure; i.e., both schemes (equations (6) and (7)) take place during the reduction of copper chromite.…”

Section: Cuo(traces) [Cu ] [Cr ] O (Oh)mentioning

confidence: 84%

In situ high-temperature X-ray diffraction measurements: Application to the study of heterogeneous catalysts

Plyasova

Kardash

2012

J Struct Chem

Self Cite

View full text Add to dashboard Cite

When characterizing the phase composition and structure of catalysts, researchers are faced with the problem of reversible effects of temperature and gas medium during their preparation, activation, or operation. Therefore, particular attention is paid to the methods of their research in appropriate conditions, i.e., in situ high-temperature X-ray diffraction. The theoretical framework and experimental features of high-temperature X-ray diffraction techniques are examined. Examples are given of their effective application to the study of the structural features of oxide catalysts under close-to-real conditions. Keywords: in situ high-temperature X-ray diffraction, thermal X-ray diffraction, oxide catalysts, phase composition, structure in the model conditions of preparation, activation, and operation.

show abstract

“…Indeed, as shown by many studies on the reducibility of CuCr 2 O 4 , 26−28 in the presence of hydrogen the catalyst decays slowly by reduction of copper oxide to copper. This reaction takes place in two steps: 8,27 initially by transformation of structural hydroxyls into adsorbed H 2 O, and next by its deadsorption. Formation of low oxidation states of copper (generally observed for T < 723 K) has a negative effect on the structural stability of CuCr 2 O 4 with the irreversible loss of the spinel structure, resulting in a decay in catalytic activity.…”

Section: Resultsmentioning

confidence: 99%

Ethanol Steam Reforming in a Two-Step Process. Short-Time Feasibility Tests

Vinci

Chiodo²,

Papageridis

et al. 2013

Energy Fuels

View full text Add to dashboard Cite

This paper describes a two-step process for hydrogen generation consisting of low-temperature (573 K) dehydrogenation of ethanol over copper chromite, followed by steam reforming (SR) over Ni/MgO at higher temperature (923 K). Advantages compared to direct SR of ethanol comprise suppression of coke formation. Water also moderates the rate of reduction of copper and promotes the stability of copper chromite at temperatures below 673 K. The two-step process requires a quantity of catalyst for the low-temperature step in excess of that for the high-temperature SR catalyst in order to ensure adequate conversion levels of ethanol in the first step.

show abstract

Mechanistic features of reduction of copper chromite and state of absorbed hydrogen in the structure of reduced copper chromite

Cited by 16 publications

References 14 publications

Influence of reduction time of copper based catalysts: Cu/Al₂O₃ and CuCr₂O₄ on hydrogenolysis of glycerol

Influence of reduction time of copper based catalysts: Cu/Al₂O₃ and CuCr₂O₄ on hydrogenolysis of glycerol

In situ high-temperature X-ray diffraction measurements: Application to the study of heterogeneous catalysts

Ethanol Steam Reforming in a Two-Step Process. Short-Time Feasibility Tests

Contact Info

Product

Resources

About

Mechanistic features of reduction of copper chromite and state of absorbed hydrogen in the structure of reduced copper chromite

Cited by 16 publications

References 14 publications

Influence of reduction time of copper based catalysts: Cu/Al2O3 and CuCr2O4 on hydrogenolysis of glycerol

Influence of reduction time of copper based catalysts: Cu/Al2O3 and CuCr2O4 on hydrogenolysis of glycerol

In situ high-temperature X-ray diffraction measurements: Application to the study of heterogeneous catalysts

Ethanol Steam Reforming in a Two-Step Process. Short-Time Feasibility Tests

Contact Info

Product

Resources

About

Influence of reduction time of copper based catalysts: Cu/Al₂O₃ and CuCr₂O₄ on hydrogenolysis of glycerol

Influence of reduction time of copper based catalysts: Cu/Al₂O₃ and CuCr₂O₄ on hydrogenolysis of glycerol