Intraosseous ganglion in the subchondral region of the lateral femoral condyle in an 11-year-old girl: a case report

We report the case of a patient with intraosseous ganglion in the lateral femoral condyle. An 11-year-old girl presented with right knee pain following a twisting injury. Plain radiographs of the knee showed a small circumscribed radiolucency with a thin sclerotic margin in the subchondral region of the lateral femoral condyle. Although the image findings and location are not typical, the lesion was tentatively diagnosed as osteochodritis dissecans. Six months after the conservative treatment with a break from vigorous sports activities, the size of the bony lesion had not decreased. Thus, we performed arthroscopy to make a definitive diagnosis. Arthroscopic examination revealed an area with dimple and surface irregularity at the lateral femoral condyle. On excision of the overlying tissue, the lesion was cystic containing brown mucous fluid. No association between the cyst and the articular structures was observed. Histologic examination of the resected cyst wall showed dense fibrous tissue with spotty areas of calcification. Base on these findings, we made a diagnosis of intraosseous ganglion. At the nine-month postoperative follow-up, the radiographic examination showed healing of the lesion. We speculate that the lesion in this case might have occurred as a result of repetitive overstress or microtrauma

Tuning of catalytic activity by thermoelectric materials for carbon dioxide hydrogenation

An innovative use of a thermoelectric material (BiCuSeO) as a support and promoter of catalysis for CO2 hydrogenation is reported here. It is proposed that the capability of thermoelectric materials to shift the Fermi level and work function of a catalyst lead to an exponential increase of catalytic activity for catalyst particles deposited on its surface. Experimental results show that the CO2 conversion and CO selectivity are increased significantly by a thermoelectric Seebeck voltage. This suggests that the thermoelectric effect can not only increase the reaction rate but also change chemical equilibrium, which leads to the change of thermodynamic equilibrium for the conversion of CO2 in its hydrogenation reactions. It is also shown that this thermoelectric promotion of catalysis enables BiCuSeO oxide itself to have a high catalytic activity for CO2 hydrogenation. The generic nature of the mechanism suggests the possibility that many catalytic chemical reactions can be tuned in situ to achieve much higher reaction rates, or at lower temperatures, or have better desired selectivity through changing the backside temperature of the thermoelectric support

Recent progress in ceria-based catalysts for the dry reforming of methane: a review

The mitigation of CO2 and CH4 emissions is feasible by transforming them into valuable syngas via the dry reforming of methane (DRM). However, the problem of catalyst deactivation has restricted its industrial application. Therefore, the development of catalysts for an effective reforming process has been attracted enormous attention. Ceria has a high potential as it can serve as both catalyst support and metal active site for adsorption and dissociation of CO2 and CH4. Material properties, such as redox and acid/base properties, and oxygen storage capacity, greatly affect catalytic behavior and performance, as well as coke inhibition in the DRM. This review aims to provide an up-to-date summary on the DRM over ceria-based catalysts, including aspects of the catalysts, reaction mechanism, deactivation, and regeneration studies. This review also proposes governing factors and new ways for improving the process, to provide a more rational to designing an ideal ceria-based catalyst for DRM

Infrared Studies on Bimetallic Copper/Nickel Catalysts Supported on Zirconia and Ceria/Zirconia

ABSTRACT: Infrared spectroscopy has been employed for a detailed characterization of ZrO(2) and CeO(2)/ZrO(2) supported nickel and copper/nickel catalysts to be utilized for methane decomposition. Adsorption of CO at 303 K was performed in order to determine the surface composition and accessible adsorption sites. Alloy formation occurred during reduction, as indicated by a red-shift of the vibrational band of CO on Ni: by 27 cm(−1) on nickel-rich CuNi alloy, by 34 cm(−1) on 1:1 Cu:Ni and by 36 cm(−1) on copper-rich CuNi alloy. CuNi alloy formation was confirmed by X-ray absorption spectroscopy during reduction revealing a considerably lower reduction temperature of NiO in the bimetallic catalyst compared to the monometallic one. However, hydrogen chemisorption indicated that after reduction at 673 K copper was enriched at the surface of the all bimetallic catalysts, in agreement with IR spectra of adsorbed CO. In situ IR studies of methane decomposition at 773 K demonstrated that the addition of Cu to Ni strongly reduced coking occurring preferentially on nickel, while maintaining methane activation. Modification of the zirconia by ceria did not have much effect on the adsorption and reaction properties. Ceria-zirconia and zirconia supported samples exhibited very similar properties and surface chemistry. The main difference was an additional IR band of CO adsorbed on metallic copper pointing to an interaction of part of the Cu with the ceria. GRAPHICAL ABSTRACT: [Figure: see text

Study of catalytic systems for the exploitation of carbon dioxide to produce liquid fuels

Sustainability requires two major inputs: renewable energy and raw material resources and environmental protection. Biogas is a biomass derivative, primarily comprised of methane and carbon dioxide. The most suitable process for the utilization of biogas is the reforming of methane by carbon dioxide or else the Dry Reforming of Methane (DRM) to synthesis gas and then to liquid energy carriers via the Fischer–Tropsch technology. DRM reaction has many advantages: no CO2 separation processes and no steam are needed, thermodynamic conversions are high and the synthesis gas produced has H2/CO ratios suitable for the Fischer–Tropsch synthesis. Furthermore, as DRM has a large heat of reaction and is reversible, it has potential applications in chemical energy storage and transmission systems. However, the process faces problems, the most serious being catalyst’s deactivation and reactor blockage due to coke deposition. Ni-based catalysts are promising but their prone to carbon formation. In the present thesis, the CO2 reforming of methane has been investigated over Ni-based catalytic systems. Various single metal oxides, binary and ternary mixed oxides have been selected as supports in order to improve: nickel dispersion and the formation small nickel crystallites, the availability of surface oxygen species and the CO2 adsorption and activation. Supports and catalysts were prepared following various procedures and were characterized with respect to their specific surface area (BET method) and their porosity (BJH method, phase composition (XRD, DRS), size of crystallites (XRD, Scherrer equation), coordination and electronic environment of the cations (DRS), reducibility (H2-TPR). The catalytic performance of the prepared materials (reduced in situ at 1073 K) for the dry reforming of methane was studied for 24h in a fixed bed plug flow reactor operating under the following conditions: 973 K, 1 atm, undiluted 50%CH4-50%CO2. The carbonaceous deposits on the used catalysts were measured by temperature programmed hydrogenation (TPH). Images of the used catalysts were obtained by SEM equipped with EDS. [...]Η βιώσιμη ανάπτυξη (Sustainability) επιβάλλει την αξιοποίηση ανανεώσιμων/ανακυκλώσιμων υλικών και πηγών ενέργειας, λαμβάνοντας πάντα υπόψη και την ανάγκη για προστασία του περιβάλλοντος. Το βιοαέριο, ένα από τα παράγωγα της βιομάζας που αποτελείται κυρίως από CO2 και CH4, είναι μια ελκυστική ανανεώσιμη πηγή άνθρακα και η αξιοποίησή του θα μπορούσε να είναι ωφέλιμη τόσο από οικονομικής όσο και περιβαλλοντικής πλευράς. Η καταλληλότερη διαδικασία για την πλήρη αξιοποίηση του βιοαερίου καθώς και του φυσικού αερίου με μεγάλη περιεκτικότητα σε διοξείδιο του άνθρακα είναι η αναμόρφωση του CH4 με CO2 ή ξηρή αναμόρφωση του μεθανίου (Dry reforming of methane - DRM) προς παραγωγή αερίου σύνθεσης και στη συνέχεια η παραγωγή υγρών ενεργειακών φορέων μέσω της τεχνολογίας Fischer–Tropsch. Η αντίδραση DRM παρουσιάζει σημαντικά πλεονεκτήματα: δεν απαιτείται η απομάκρυνση του CO2 από την τροφοδοσία, δεν απαιτείται η χρήση ύδατος, οι θερμοδυναμικές μετατροπές είναι αρκετά υψηλές, ενώ και το αέριο σύνθεσης που παράγεται έχει την κατάλληλη αναλογία για συνθέσεις Fischer–Tropsch. Επιπλέον, η αντίδραση DRM έχει μεγάλη θερμότητα αντίδρασης και είναι αμφίδρομη, επομένως μπορεί να βρει εφαρμογή σε χημικά συστήματα αποθήκευσης ενέργειας. Όμως, η αντίδραση αντιμετωπίζει και ορισμένα προβλήματα, με το σημαντικότερο από αυτά να είναι η απενεργοποίηση του καταλύτη και το φράξιμο του αντιδραστήρα εξαιτίας της απόθεσης coke. Οι καταλύτες Ni είναι αρκετά υποσχόμενοι για την αντίδραση αυτή, αλλά είναι ευαίσθητοι στις ανθρακούχες αποθέσεις.Στην παρούσα εργασία, μελετήθηκαν καταλύτες Ni για την αντίδραση αναμόρφωσης CH4 με CO2. Διάφορα οξείδια μετάλλων, μικτά ή απλά, επιλέχθηκαν ως υποστρώματα ούτως ώστε να βελτιωθεί η διασπορά του Ni, ο σχηματισμός μικρών σωματιδίων του μετάλλου, να αυξηθεί η διαθεσιμότητα των ειδών οξυγόνου, όπως επίσης και να ευνοηθεί η προσρόφηση και ενεργοποίηση του CO2. Τα υποστρώματα παρασκευάστηκαν με διάφορες μεθόδους, και χαρακτηρίστηκαν φυσικοχημικά ως προς τη μέτρηση της ειδικής επιφάνειας (μέθοδος ΒΕΤ), το πορώδες (μέθοδος BJH), τη σύσταση (XRD, UV-Vis DRS), το μέγεθος κρυσταλλιτών (XRD, εξίσωση Scherrer), το ηλεκτρονιακό περιβάλλον και το περιβάλλον ένταξης (DRS) καθώς και την αναγωγιμότητα(H2-TPR). Η καταλυτική συμπεριφορά τους για την αντίδραση της ξηρής αναμόρφωσης του μεθανίου αξιολογήθηκε σε αντιδραστήρα σταθερής κλινης, για 24 h, σε συνθήκες: 973 Κ, 1 atm, τροφοδοσία 50%CH4-50%CO2. Ο εναποτιθέμενος άνθρακας στους χρησιμοποιημένους καταλύτες μετρήθηκε με τη μέθοδο της θερμοπρογραμματισμένης υδρογόνωσης (TPH). Εικόνες των χρησιμοποιημένων καταλυτών λήφθησαν με ηλεκτρονικό μικροσκόπιο σάρωσης (SEM), εφοδιασμένο με αναλύτη EDS. […

CO Methanation for Synthetic Natural Gas Production

Energy from woody biomass could supplement renewable energy production towards the replacement of fossil fuels. A multi-stage process involving gasification of wood and then catalytic transformation of the producer gas to synthetic natural gas (SNG) represents progress in this direction. SNG can be transported and distributed through the existing pipeline grid, which is advantageous from an economical point of view. Therefore, CO methanation is attracting a great deal of attention and much research effort is focusing on the understanding of the process steps and its further development. This short review summarizes recent efforts at Paul Scherrer Institute on the understanding of the reaction mechanism, the catalyst deactivation, and the development of catalytic materials with benign properties for CO nnethanation