Storage capacity and oxygen mobility in mixed oxides from transition metals promoted by cerium

Perdomo, Camilo; Pérez, Alejandro Escánez; Molina, Rafael; Moreno, Sonia

doi:10.1016/j.apsusc.2016.04.145

Cited by 14 publications

(8 citation statements)

References 21 publications

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“…The Mn showed multiple peaks due to different oxidation states (Table 5) and finally, in binary samples Mn-Cu (x:y), comparing the reduction temperatures of the solid with only Mn or Cu, there was evidence of a shift to lower temperatures for the mixed oxides Mn-Cu, with a more pronounced shift in the Mn-Cu oxide (1:2) being observed, which indicated that the reduction of manganese oxides is easier when Cu is added (Table 3). This result can be attributed to the oxygen mobility increasing due to the presence of a second transition metal (Cu) and the decrease in particle sizes that can facilitate the redox behavior of the materials [32]. When Cu is added within the mixed oxides, lower reducibility temperatures are evident, which would favor the reaction to moderate conditions.…”

Section: Discussionmentioning

confidence: 99%

Degradation of Crystal Violet by Catalytic Wet Peroxide Oxidation (CWPO) with Mixed Mn/Cu Oxides

et al. 2019

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The environment protection has been the starting point for the development of new technologies, which allow the control of highly toxic substances present in the effluents of various industries, whose removal is not feasible by conventional methods. In this research, mixed oxide catalysts Mn and Cu in different molar ratios were prepared from the autocombustion method and characterized by XRD, XRF, TPR-H2, and N2 adsorption–desorption isotherms. The solids were evaluated in the catalytic wet peroxide oxidation of crystal violet (CV) with mild conditions of reaction: 25 °C, normal pressure, airflow of 2 mL/min, and H2O2 0.1 M (2 mL/h). The experimental results indicated degradations of 100% of CV, conversion of the total organic carbon (TOC) of 74%, and elimination of chemical oxygen demand (COD) of 71% in 90 min of reaction. Additionally, the selectivity was monitored by CG-MS, finding that there was almost complete mineralization in a short reaction time, generating intermediate products such as carboxylic acids, alcohols, and amines that do not cause a serious risk to the environment. The Mn–Cu catalyst with molar ratios of 1:2 was the most promising catalyst, displaying a cooperative effect between the two metals, and demonstrating the importance of the redox properties for the elimination of CV dye in wastewater.

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Section: Discussionmentioning

confidence: 99%

Degradation of Crystal Violet by Catalytic Wet Peroxide Oxidation (CWPO) with Mixed Mn/Cu Oxides

et al. 2019

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“…In the past several years, OSMs based on transition metal species (e.g., Cu, Fe, Mn, Co) have attracted considerable attention due to their relatively low cost but high catalytic activity, as well as their changeable valences. [4][5][6] As an important transition metal element with variable oxidation states, manganese oxides (MnO 2 , Mn 2 O 3 , Mn 3 O 4 , or MnO), especially MnO 2 , have been widely studied as catalysts and catalyst supports for oxidation reactions because of their redox capabilities, high oxygen storage capacity in the crystalline lattice, abundant amount, relatively low price and environmental friendliness. [7][8][9][10][11][12] However, the catalytic activity of pure MnO 2 is still not high enough, which may result from the poor oxygen transfer in pure MnO 2 at low temperature.…”

Section: Introductionmentioning

confidence: 99%

Nanocrystalline CeO2−δ coated β-MnO2 nanorods with enhanced oxygen transfer property

Huang

Zhao

Chang

et al. 2018

Applied Surface Science

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In this research, β-MnO 2 nanorods were synthesized by a hydrothermal method, followed by a facile precipitation method to obtain nanocrystalline CeO 2-δ coated β-MnO 2 nanorods. The as-prepared samples were characterized by XRD, HRTEM, FESEM, XPS and in-situ high-temperature XRD. The HRTEM results show that well dispersed CeO 2-δ nanocrystals sized about 5 nm were coated on the surface of β-MnO 2 nanorods. The oxygen storage and transfer property of as-synthesized materials were evaluated using TGA under various atmospheres (air, pure N 2 , and 5%H 2 /95%Ar). The TGA results indicate that CeO 2-δ modification could favour the reduction of Mn 4+ to Mn 3+ and/or Mn 2+ at lower temperature as compared with pure β-MnO 2 nanorods and the physically mixed CeO 2-δ-β-MnO 2 under low oxygen partial pressure conditions (i.e., pure N 2 , 5%H 2 /95%Ar). Specifically, CeO 2-δ @β-MnO 2 sample can exhibit 7.5 wt% weight loss between 100 and 400 o C under flowing N 2 and 11.4 wt% weight loss between 100 and 350 o C under flowing 5%H 2 /95%Ar. During the reduction process under pure N 2 or 5%H 2 /95%Ar condition, the oxygen ions in β-MnO 2 nanorods are expected to be released to the surroundings in the form of O 2 or H 2 O with the coated CeO 2-δ nanocrystals acting as mediator as inferred from the synergistic effect between the well-interacted CeO 2-δ nanocrystals and β-MnO 2 nanorods.

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“…e investigation of the influence of various metal oxides on the behaviour of molybdenum oxide towards the oxidation of toluene with molecular oxygen concluded that toluene oxidation decreases in the following order: support oxides ≥ molybdenum oxide monolayer catalysts > molybdate salts > crystalline molybdenum oxide, but the benzaldehyde and benzoic acid selectivities follow the opposite trend [15]. Although there is a large number of catalysts described in the literature and in the patent literature composed of the vanadium oxides systems modified by various promoters, supported on carriers Al2O 3 , SiO 2 , TiO 2 , and transition metal oxides and favorable for the catalytic gas-phase toluene oxidation to benzaldehyde [17][18][19][20][21][22][23][24], but the toluene conversion is very poor at low temperature ( less than 10%). is catalyst system favors the formation of benzoic acid and degradation of carbon dioxide and benzaldehyde selectivity is not very satisfactory.…”

Section: Introductionmentioning

confidence: 99%

Direct Benzyl Alcohol and Benzaldehyde Synthesis from Toluene over Keggin-Type Polyoxometalates Catalysts: Kinetic and Mechanistic Studies

Allam

Mansouri

Hocine

2019

Journal of Chemistry

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e catalytic activity of various Keggin polyoxometalate catalysts has been investigated in the gas-phase partial oxidation of toluene to produce benzyl alcohol and benzaldehyde. e catalyst systems HPMo 12 O 40 , HPMo 11 VO 40 , FePMo 12 O 40 , and PMo 11 FeO 39 were prepared and characterized by FT-IR, UV-visible, SEM, XRD, TGA, and cyclic voltammetry. e acid/base properties were evaluated using the decomposition of isopropanol. Catalytic studies were carried under atmospheric pressure and over the temperature range 200°C-350°C, using carbon dioxide as a mild oxidant. Toluene conversion and product distribution depend mainly on the catalyst composition and operating conditions. In addition to benzaldehyde, benzyl alcohol is obtained with a high selectivity on the PMo 11 FeO 39 catalyst. e kinetic data show that the reoxidation of the reduced catalyst is the rate-limiting step for the partial oxidation reaction of toluene.

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Storage capacity and oxygen mobility in mixed oxides from transition metals promoted by cerium

Cited by 14 publications

References 21 publications

Degradation of Crystal Violet by Catalytic Wet Peroxide Oxidation (CWPO) with Mixed Mn/Cu Oxides

Degradation of Crystal Violet by Catalytic Wet Peroxide Oxidation (CWPO) with Mixed Mn/Cu Oxides

Nanocrystalline CeO2−δ coated β-MnO2 nanorods with enhanced oxygen transfer property

Direct Benzyl Alcohol and Benzaldehyde Synthesis from Toluene over Keggin-Type Polyoxometalates Catalysts: Kinetic and Mechanistic Studies

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