Nature of Copper Active Sites in the Carbon Monoxide Oxidation on CuAl2O4and CuCr2O4Spinel Type Catalysts

Abstract:The effect of the sodium addition mode was investigated on model Cu/FER selective catalytic reduction (SCR) catalysts with two copper loadings (2.8 wt. % and 6.1 wt. %) in order to compare samples with or without over-exchanged copper. Na was added by wet-impregnation using two solvents: water or ethanol. Catalysts were evaluated in Standard and Fast-SCR conditions, as well as in NO and NH 3 oxidation. They were characterized by H 2 -TPR, NO and NH 3 adsorption monitored by FT-IR. As expected, whatever the copper loading, ammonia adsorption capacity was decreased by Na additions. Interestingly, characterizations also showed that Na impregnation in water favors the migration of the Cu-exchanged species, leading to the formation of CuO extra-framework compounds. Consequently, for both copper loadings, Na impregnation in water led to a stronger catalyst deactivation than impregnation in ethanol. Finally, the NO x conversion at low temperature (250 • C) appeared mainly affected by the loss in NH 3 adsorption capacity whereas the deNO x deactivation at high temperature (500 • C) was rather governed by the decrease in the exchanged copper ratio, which also induced a partial inhibition of NO and NH 3 oxidation behaviors.

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“…Figure S2 in Supplementary Materials). However, different species of Cu 2+ and Cu + may be also reduced in this temperature range [23,25].…”

Section: Temperature Programmed Reduction By Hydrogen (H 2 -Tpr)mentioning

confidence: 94%

Influence of the Sodium Impregnation Solvent on the Deactivation of Cu/FER-Exchanged Zeolites Dedicated to the SCR of NOx with NH3

et al. 2017

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“…CuO/Al 2 O 3 and CuO/Cr 2 O 3 with lower Cu surface area (Table 1) and poor reducibility ( Figure 4) showed lower activities of DME SR, regardless of the band proportion for reduced copper. The CuO/Al 2 O 3 and CuO/Cr 2 O 3 show higher I sat /I pp (satellite/main peak ratio), which is usually observed in a normal spinel structure (Patterson et al, 1976;Severino et al, 1998), as evidenced in XRD patterns of CuO/Cr 2 O 3 in Figure 2. In the case of copper-based catalysts with high I sat /I pp , there is no obvious correlation between band proportion for reduced copper and catalytic activ- ity of DME SR. 2.2 DME steam reforming over hybrid catalysts of CuO/Ga 2 O 3 with different copper molar ratio Since CuO/Ga 2 O 3 has better physical properties such as Cu surface area, amount of acidic sites and reducibility, the effect of copper concentration on DME SR over hybrid catalyst of CuO/Ga 2 O 3 was investigated as shown in Figure 6.…”

Section: Journal Of Chemical Engineering Of Japanmentioning

confidence: 90%

Characteristics of Hybrid Catalysts from Copper-Based Metal Oxide and .GAMMA.-Al2O3 for Steam Reforming of Dimethyl Ether

Yun

Bazardorj

Ihm

2009

J. Chem. Eng. Japan

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DME hydrolysis to methanol is accelerated by the presence of acidic sites, and the methanol conversion to hydrogen proceeds relatively fast over copper-based catalysts. Since the equilibrium of DME hydrolysis seems to be shifted to the right due to methanol SR over copper-based catalysts, the catalytic activity of DME SR seems to mainly depend on the design of copper-based catalysts. In this work, different metal oxides were introduced into the copper-based catalyst, and their effects on the physical properties such as copper surface area, acidity and reducibility were investigated. The catalytic performances were analyzed mainly in terms of copper reducibility.

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“…Therefore, the Bi2O3/ CuCr2O4-CuO core/shell nanomaterials provide promising for pollution treatment in car exhaust purification. Pre-reduced copper chromite catalysts have been shown to be more active than unreduced ones [232]. Pre-reduction with H2 produced higher activity than prereduction with CO, which can be attributed to a higher surface concentration of active species after the former treatment.…”

Section: Oxidation Of Carbon Monoxidementioning

confidence: 98%

“…Copper chromite catalysts have been studied in detail for CO oxidation. The studies have been attributed to the catalytic activity and stability tests [225,226], postulating mechanisms [227], characterization of catalysts [228,229], rapid evaluation of the catalysts [230], search for the active sites on the catalysts [231,232], kinetics of the reaction [228,233], catalysts deactivation [229,234], etc. Pantaleo et al [235] reported the catalytic tests in CO oxidation indicated a synergetic effect between copper and chromium in the mixed oxides supported on silica and calcined at 500 0 C. Xavier et al [236] found that Cu-Cr based catalysts are effective for CO oxidation at lower temperatures.…”

Section: Oxidation Of Carbon Monoxidementioning

confidence: 99%

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Applications and Preparation Methods of Copper Chromite Catalysts: A Review

Прасад

2011

Bull. Chem. React. Eng. Catal.

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In this review article various applications and preparation methods of copper chromite catalysts have been discussed. While discussing it is concluded that copper chromite is a versatile catalyst which not only catalyses numerous processes of commercial importance and national program related to defence and space research but also finds applications in the most concerned problem worldwide i.e. environmental pollution control. Several other very useful applications of copper chromite catalysts are in production of clean energy, drugs and agro chemicals, etc. Various preparation methods about 15 have been discussed which depicts clear idea about the dependence of catalytic activity and selectivity on way of preparation of catalyst. In view of the globally increasing interest towards copper chromite catalysis, reexamination on the important applications of such catalysts and their useful preparation methods is thus the need of the time. This review paper encloses 369 references including a well-conceivable tabulation of the newer state of the art.

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Nature of Copper Active Sites in the Carbon Monoxide Oxidation on CuAl2O4and CuCr2O4Spinel Type Catalysts

Cited by 249 publications

References 37 publications

Influence of the Sodium Impregnation Solvent on the Deactivation of Cu/FER-Exchanged Zeolites Dedicated to the SCR of NOx with NH3

Influence of the Sodium Impregnation Solvent on the Deactivation of Cu/FER-Exchanged Zeolites Dedicated to the SCR of NOx with NH3

Characteristics of Hybrid Catalysts from Copper-Based Metal Oxide and .GAMMA.-Al2O3 for Steam Reforming of Dimethyl Ether

Applications and Preparation Methods of Copper Chromite Catalysts: A Review

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