Total Oxidation of Propane Using CeO2 and CuO-CeO2 Catalysts Prepared Using Templates of Different Nature

[EN] Several CeO2 and CuO-CeO2 catalysts were prepared using different methods, i.e., a homogeneous precipitation with urea, a nanocasting route using CMK-3 carbon as a hard template and a sol¿gel process using Poly(methyl methacrylate) (PMMA) polymer as a soft template, and tested in the total oxidation of propane. The catalysts were characterized by a number of physicochemical techniques (XRD, N2 adsorption, TPR, XPS, Raman spectroscopy) showing distinct characteristics. For each series, Cu-Ce-O catalysts with low Cu-loadings (5 wt % CuO) showed the highest activity, higher than those samples either without copper or with high Cu-loading (13 wt % CuO). The incorporation of copper leads to an increase of the concentration of bulk defects but if the Cu-loading is too high the surface area drastically falls. The highest activity in the total oxidation of propane was achieved by Cu-containing ceria catalysts synthesized using a polymer as a template, as this method yields high surface area materials. The surface area and the number of bulk/sub-surface defects of the ceria seem to be the main properties determining the catalytic activityThe authors would like to acknowledge the DGICYT in Spain CTQ2012-37925-C03-2, CTQ2015-68951-C3-1-R, CTQ2015-68951-C3-3-R. Authors from ITQ also thank Project SEV-2012-0267 for financial support. B.S, R.S and A.M.D also thank UV-INV-AE16-484416.Solsona, B.; Sanchis, R.; Dejoz, AM.; Garcia, T.; Ruiz-Rodríguez, L.; López Nieto, JM.; Cecilia, JA.... (2017). Total Oxidation of Propane Using CeO2 and CuO-CeO2 Catalysts Prepared Using Templates of Different Nature. Catalysts. 7(4):96-110. https://doi.org/10.3390/catal7040096S961107

Total oxidation of VOCs on mesoporous iron oxide catalysts: soft chemistry route versus hard template method

[EN] A comparative study on the total oxidation of volatile organic compounds, VOCs, on mesoporous iron oxide catalysts prepared by soft chemistry route versus those achieved by hard template methodThe authors would like to acknowledge the DGICYT in Spain (CTQ2012-37925-C03-1, CTQ2012-37925-C03-2, CTQ2012-37925-C03-3 and CTQ2012-37984-C02-01) and FEDER for financial support. We also thank the University of Valencia and SCSIE-UV for assistance.Solsona Espriu, BE.; Garcia, T.; Sanchis Martinez, R.; Soriano Rodríguez, MD.; Moreno, M.; Rodríguez-Castellon, E.; Agouram, S.... (2016). Total oxidation of VOCs on mesoporous iron oxide catalysts: soft chemistry route versus hard template method. The Chemical Engineering Journal and the Biochemical Engineering Journal. 290:273-281. https://doi.org/10.1016/j.cej.2015.12.109S27328129

Promoting the activity and selectivity of high surface area Ni-Ce-O mixed oxides by gold deposition for VOC catalytic combustion

Gold supported on nickel cerium oxide catalysts (Ni–Ce–O) have been studied for the total oxidation of propane, as a model for hydrocarbon volatile organic compound emission control. High surface area Ni–Ce–O catalysts were synthesized using a very simple evaporation method, where cerium and nickel salts were evaporated in the presence of a mixture of methanol and oxalic acid. Gold catalysts were prepared following a deposition–precipitation method. A very efficient catalyst for the oxidation of propane, in terms of both activity and selectivity, was obtained. This high activity has been related to the high surface area of the catalyst (and therefore to the presence of more active sites available), a high reducibility of Ni-sites and a low strength of the Ni–O bond. Additionally, all the gold catalysts tested are highly selective towards CO2 (close to 100%), in contrast to gold-free catalysts

Evolution of the optimal catalytic systems for the oxidative dehydrogenation of ethane: The role of adsorption in the catalytic performance

Three samples that correspond to the evolution of optimal catalytic systems for the oxidative dehydrogenation of ethane have been synthesized and compared in terms of catalytic behavior and adsorption properties: (i) vanadium oxide supported on alumina, (ii) Sn-promoted NiO, and (iii) multicomponent MoVTeNbO with the M1 structure. The main difference in catalytic performance lies in the extent of the overoxidation of the ethylene formed, following the order VOx/Al2O3 > NiSnOx > MoVTeNb-M1. Accordingly, the selectivity to ethylene at medium and high ethane conversion follows the order MoVTeNb-M1 > NiSnOx > VOx/Al2O3. These results are confirmed by the relative reaction rates observed for the oxidation of ethane and the oxidation of ethylene. Microcalorimetry studies indicate that the heat of adsorption of both ethane and ethylene is the highest in the most selective MoVTeNb-M1 sample. Thus, the low olefin decomposition in the MoVTeNb-M1 catalyst is not due to weaker adsorption of ethylene but to the reduced ability of its active sites to activate ethylene. The same conclusion regarding the MoVTeNb-M1 catalyst can be drawn by FT-IR of adsorbed ethylene. On the other hand, NiSnOx active sites present a high overoxidation ability, as demonstrated by the notorious formation of oxygenated species, precursors of COx. However, the ethylene decomposition is rather mild because of the existence of many free Lewis sites not involved in the overoxidation reaction. In contrast, in the case of the VOx/Al2O3 catalyst, almost all active sites are involved in the oxidation path, so that the olefins decompose readily

Evolution of the optimal catalytic systems for the oxidative dehydrogenation of ethane: The role of adsorption in the catalytic performance

Three samples that correspond to the evolution of optimal catalytic systems for the oxidative dehydrogenation of ethane have been synthesized and compared in terms of catalytic behavior and adsorption properties: (i) vanadium oxide supported on alumina, (ii) Sn-promoted NiO, and (iii) multicomponent MoVTeNbO with the M1 structure. The main difference in catalytic performance lies in the extent of the overoxidation of the ethylene formed, following the order VOx/Al2O3 > NiSnOx > MoVTeNb-M1. Accordingly, the selectivity to ethylene at medium and high ethane conversion follows the order MoVTeNb-M1 > NiSnOx > VOx/Al2O3. These results are confirmed by the relative reaction rates observed for the oxidation of ethane and the oxidation of ethylene. Microcalorimetry studies indicate that the heat of adsorption of both ethane and ethylene is the highest in the most selective MoVTeNb-M1 sample. Thus, the low olefin decomposition in the MoVTeNb-M1 catalyst is not due to weaker adsorption of ethylene but to the reduced ability of its active sites to activate ethylene. The same conclusion regarding the MoVTeNb-M1 catalyst can be drawn by FT-IR of adsorbed ethylene. On the other hand, NiSnOx active sites present a high overoxidation ability, as demonstrated by the notorious formation of oxygenated species, precursors of COx. However, the ethylene decomposition is rather mild because of the existence of many free Lewis sites not involved in the overoxidation reaction. In contrast, in the case of the VOx/Al2O3 catalyst, almost all active sites are involved in the oxidation path, so that the olefins decompose readily.The authors acknowledge the Spanish Ministry of Science, Innovation and Universities (MCIU) for their funding (RTl2018-099668-B-C21, MAT2017-84118-C2-1-R and MAT2017-87500-P) and FEDER. The authors from ITQ also thank Programa Severo Ochoa (SEV-2016-0683). A.A. acknowledges the Severo Ochoa Excellence Program for his grant (BES-2017-080329).Peer reviewe

Evolution of the optimal catalytic systems for the oxidative dehydrogenation of ethane: The role of adsorption in the catalytic performance

Three samples that correspond to the evolution of optimal catalytic systems for the oxidative dehydrogenation of ethane have been synthesized and compared in terms of catalytic behavior and adsorption properties: (i) vanadium oxide supported on alumina, (ii) Sn-promoted NiO, and (iii) multicomponent MoVTeNbO with the M1 structure. The main difference in catalytic performance lies in the extent of the overoxidation of the ethylene formed, following the order VOx/AlO > NiSnOx > MoVTeNb-M1. Accordingly, the selectivity to ethylene at medium and high ethane conversion follows the order MoVTeNb-M1 > NiSnOx > VOx/AlO These results are confirmed by the relative reaction rates observed for the oxidation of ethane and the oxidation of ethylene. Microcalorimetry studies indicate that the heat of adsorption of both ethane and ethylene is the highest in the most selective MoVTeNb-M1 sample. Thus, the low olefin decomposition in the MoVTeNb-M1 catalyst is not due to weaker adsorption of ethylene but to the reduced ability of its active sites to activate ethylene. The same conclusion regarding the MoVTeNb-M1 catalyst can be drawn by FT-IR of adsorbed ethylene. On the other hand, NiSnOx active sites present a high overoxidation ability, as demonstrated by the notorious formation of oxygenated species, precursors of CO. However, the ethylene decomposition is rather mild because of the existence of many free Lewis sites not involved in the overoxidation reaction. In contrast, in the case of the VO/AlO catalyst, almost all active sites are involved in the oxidation path, so that the olefins decompose readily.The authors acknowledge the Spanish Ministry of Science, Innovation and Universities (MCIU) for their funding (RTl2018-099668-B-C21, MAT2017-84118-C2-1-R and MAT2017-87500-P) and FEDER. The authors from ITQ also thank Programa Severo Ochoa (SEV-2016-0683). A.A. acknowledges the Severo Ochoa Excellence Program for his grant (BES-2017-080329)

Metastatic Versus Osteoporotic Vertebral Fractures on MRI: A Blinded, Multicenter, and Multispecialty Observer Agreement Evaluation.

MRI is assumed to be valid for distinguishing metastatic vertebral fractures (MVFs) from osteoporotic vertebral fractures (OVFs). This study assessed (1) concordance between the image-based diagnosis of MVF versus OVF and the reference (biopsy or follow-up of >6 months), (2) interobserver and intraobserver agreement on key imaging findings and the diagnosis of MVF versus OVF, and (3) whether disclosing a patient's history of cancer leads to variations in diagnosis, concordance, or agreement. This retrospective cohort study included clinical data and imaging from 203 patients with confirmed MVF or OVF provided to 25 clinicians (neurosurgeons, radiologists, orthopedic surgeons, and radiation oncologists). From January 2018 through October 2018, the clinicians interpreted images in conditions as close as possible to routine practice. Each specialist assessed data twice, with a minimum 6-week interval, blinded to assessments made by other clinicians and to their own previous assessments. The kappa statistic was used to assess interobserver and intraobserver agreement on key imaging findings, diagnosis (MVF vs OVF), and concordance with the reference. Subgroup analyses were based on clinicians' specialty, years of experience, and complexity of the hospital where they worked. For diagnosis of MVF versus OVF, interobserver agreement was fair, whereas intraobserver agreement was substantial. Only the latter improved to almost perfect when a patient's history of cancer was disclosed. Interobserver agreement for key imaging findings was fair or moderate, whereas intraobserver agreement on key imaging findings was moderate or substantial. Concordance between the diagnosis of MVF versus OVF and the reference was moderate. Results were similar regardless of clinicians' specialty, experience, and hospital category. When MRI is used to distinguish MVF versus OVF, interobserver agreement and concordance with the reference were moderate. These results cast doubt on the reliability of basing such a diagnosis on MRI in routine practice