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1. Observing Chemical and Morphological Changes in a Cu@TiO _x Core@Shell Catalyst: Impact of Reversible Metal-Oxide Interactions on CO ₂ Activation and Hydrogenation

   https://doi.org/10.1021/acscatal.4c02694  

   Deng, Kaixi; Chen, Xiaobo; Moncada, Jorge; Salvatore, Kenna L; Rui, Ning; Xu, Wenqian; Xiang, Shuting; Marinkovic, Nebojsa; Frenkel, Anatoly I; Zhou, Guangwen; et al (August 2024, ACS Catalysis)

   A combination of several in situ techniques (XRD, XAS, AP-XPS, and E-TEM) was used to explore links between the structural and chemical properties of a Cu@TiOx catalyst under CO2 hydrogenation conditions. The active phase of the catalyst involved an inverse oxide/metal configuration, but the initial core@shell motif was disrupted during the pretreatment in H2. As a consequence of strong metal–support interactions, the titania shell cracked, and Cu particles migrated from the core to on top of the oxide with the simultaneous formation of a Cu–Ti–Ox phase. The generated Cu particles had a diameter of 20–40 nm and were decorated by small clusters of TiOx (<5 nm in size). Results of in situ XAS and XRD and images of E-TEM showed a very dynamic system, where the inverse oxide/metal configuration promoted the reactivity of the system toward CO2 and H2. At room temperature, CO2 oxidized the Cu nanoparticles (CO2,gas → COgas + Ooxide) inducing a redistribution of the TiOx clusters and big modifications in catalyst surface morphology. The generated oxide overlayer disappeared at elevated temperatures (>180 °C) upon exposure to H2, producing a transient surface that was very active for the reverse water–gas shift reaction (CO2 + H2 → CO + H2O) but was not stable at 200–350 °C. When oxidation and reduction occurred at the same time, under a mixture of CO2 and H2, the surface structure evolved toward a dynamic equilibrium that strongly depended on the temperature. Neither CO2 nor H2 can be considered as passive reactants. In the Cu@TiOx system, morphological changes were linked to variations in the composition of metal-oxide interfaces which were reversible with temperature or chemical environment and affected the catalytic activity of the system. The present study illustrates the dynamic nature of phenomena associated with the trapping and conversion of CO2. 

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2. Cr and CeO2 promoted Ni/SBA-15 framework for hydrogen production by steam reforming of glycerol

   Abrokwah, R; Ntow, E; Jennings, T; Stevens_Boyd, R; Hossain, T; Swain, J; Bepari, S; Hassan, S; Mohammad, N; Kuila, D (November 2023, Steel in translation)

   Ni/SBA-15 meso-structured catalysts modified with chromium and CeO2 (Ni–Cr-CeO2/SBA-15) were utilized to produce hydrogen from glycerol steam reforming (GSR). The catalysts were synthesized by a one-pot hydrothermal process and extensively characterized by analytical techniques such as N2 adsorption–desorption (BET), H2-temperature programmed reduction (H2-TPR), powder X-ray diffraction (PXRD), inductively coupled plasma-optical emission spectrometry (ICP-OES), and transmission electron microscopy (TEM). The low-angle XRD reflections affirmed that the catalysts were crystalline and possessed a 2D-ordered porosity. The BET results depicted that all the catalysts exhibited a good surface area ranging from 633 to 792m2/g, and the pore sizes were consistently in the mesoporous range (between 3 and 5 nm). TEM analysis of both calcined and spent catalysts revealed that the metal active sites were embedded in the hybrid CeO2-SiO2 support. Overall, the Ni-based catalysts exhibited higher glycerol conversion -12Ni-SBA-15–99.9%, 12Ni3CeO2-SBA-15–89.4%, and 8Ni4Cr3CeO2-SBA-15–99.7%. Monometallic 12Ni/SBA-15 performed exceptionally well, while 12Cr/SBA-15 performed poorly with the highest 71.48% CO selectivity. For short-term GSR reactions, CeO2 addition to 12Ni/SBA-15 did not have any effect, whereas Cr addition resulted in a 32% decrease in H2 selectivity. The long-term stability studies of 12Ni-SBA-15 showed H2 selectivity of ~ 64% and ~ 98% glycerol conversion. However, its activity was short-lived. After 20–30 h, the H2 selectivity and conversion dropped precipitously to 40%. The doping of mesoporous Ni/SBA-15 with Cr and CeO2 remarkably enhanced the long-term stability of the catalyst for 12Ni3CeO2-SBA-15, and 8Ni4Cr3CeO2-SBA-15 catalyst which showed ~ 58% H2 selectivity and ~ 100% conversion for the entire 60 h. Interestingly, Cr and CeO2 seem to improve the shelf-life of Ni-SBA-15 via different mechanistic pathways. CeO2 mitigated Ni poisoning through coke oxidation whereas Cr bolstered the catalyst stability via maintaining a well-defined pore size, structural rigidity, and integrity of the heterogeneous framework, thereby restricting structural collapse, and hence retard sintering of the Ni active sites during the long-term 60 h of continuous reaction. Hydrogen generation from renewable biomass like glycerol could potentially serve as a sustainable energy source and could substantially help reduce the carbon footprint of the environment 

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3. Cold plasma-Metal Organic Framework (MOF)-177 breathable system for atmospheric remediation

   https://doi.org/https://doi.org/10.1016/j.jcou.2021.101642  

   Fnu Gorky; Apolo Nambo; Maria L. Carreon (July 2021, Journal of CO2 utilization)

   Non-thermal plasma Methane capture Carbon dioxide capture Metal organic framework Methanol synthesis Atmospheric remediation 1. Introduction The stabilization of CO2 and CH4 concentrations in the air to control global warming is accelerating. There are continued efforts to develop and optimize different technologies for capture and sequestration of these greenhouse gases from industrial emission sites. From these gases, CH4 is the most dominant anthropogenic greenhouse gas (after CO2). Methane can react with nitrogen oxides leading to tropospheric ozone pollution and posses a higher global warming potential (GWP) than CO2. It is 84 times more potent than CO2 over the first 20 years after release and ~28 times more potent after a century. Methane concentrations could be restored to preindustrial levels by removing ~3.2 of the 5.3 Gt of CH4 currently in the atmosphere [1]. Rather than capturing and storing the methane, CH4 could be oxidized to CO2, through the ther- modynamically favorable reaction: CH4 + 2O2 → CO2 + 2H2O; ΔHrx = –803 kJ mol–1. With the possible production of valuable condensates such as form- aldehyde and methanol when employing different reaction conditions (i. e., gas ratio, oxidant type, temperature) and rational selected catalysts. The large activation barrier associated with splitting methane’s C– H * Corresponding author. E-mail address: Maria.CarreonGarciduenas@sdsmt.edu (M.L. Carreon). https://doi.org/10.1016/j.jcou.2021.101642 The direct capture of CO2 and CH4 from the atmosphere to stabilize the concentrations in the air to control global warming is accelerating. There are continued efforts to develop and optimize different technologies for capture and sequestration of these greenhouse gases from industrial emission sites. In this work we employed MOF-177 as an efficient CO2 and CH4 adsorbent at standard temperature and pressure conditions. We demonstrated the possibility of desorbing the gases under study when employing gentle plasma pulses of He. Moreover, we per- formed the synthesis of methanol from CH4 using O2 and CO2 as oxidants respectively in the presence of MOF- 177. We observed the highest conversion for the CH4 + O2 system when employing the MOF-177 at (5:1) (CH4: O2) flow ratio of 23.5 % and methanol selectivity of 17.65 %. While the best performance for the CH4 + CO2 system at the same conditions i.e., (5:1) (CH4: O2) flow ratio was 18.4 % for the methane conversion and 11.68 % for the selectivity towards methanol. We expect this preliminary understanding of the adsorption-reaction system under non-thermal plasma environment can lead to future atmospheric remediation technologies. 

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4. Role of CO ₂ and Glycerol in the Formation of Urchin-Like Strontium Carbonate Particles

   https://doi.org/10.1021/acssuschemeng.3c07205  

   Ghorbani, Alireza; Yurkiv, Vitaliy; Gonçalves, Josué M; Amiri, Azadeh; Ritter, Timothy G; Tamadoni_Saray, Mahmoud; Shahbazian-Yassar, Reza (February 2024, ACS Sustainable Chemistry & Engineering)

   Green synthesis of micro/nanomaterials, using glycerol as a sustainable solvent, offers environmentally and health-friendly pathways. Glycerol’s versatility in a solvothermal synthesis is effective for nanoparticle production, yet its mechanistic role in carbonate material formation is unexplored. This study investigates urchin-like strontium carbonate formation via a glycerol-mediated solvothermal synthesis, employing in situ transmission electron microscopy (in situ TEM), scanning electron microscopy, density function theory (DFT), scanning transmission electron microscopy, and X-ray diffraction. In situ TEM observations unveil the initial stages of strontium hydroxide nucleation and subsequent growth as an intermediate phase. The findings suggested that the hyperbranched polymerization of glycerol plays a pivotal role in the formation of urchin-like morphology. Furthermore, the synergistic effect of glycerol and CO2 is proposed as the primary driver for the formation of strontium carbonate. Notably, observations showed a morphological transition from spherical to urchin-like with increasing reaction time. DFT studies proposed glycerol as a coadsorbent, boosting the adsorption energy of CO2 and directing its interaction with Sr(OH)2 resulting in the stable formation of SrCO3. This research provides valuable insights into the urchin-like strontium carbonate formation in a time-dependent process driven by the polymerization of glycerol and its high reactivity with dissolved CO2 at elevated temperatures. 

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5. AgNPs@ZnO hybride nanoparticles infused thermoplastic polyester elastomer and their biocide effect

   https://doi.org/10.1007/s42452-021-04365-2  

   Parra, Duclerc Fernandes; Marchini, Leonardo Guedes; Komatsu, Luiz Gustavo; de Oliveira, Camila Bassetti; Oliani, Washington Luiz; Rangari, Vijaya Kumar (April 2021, SN Applied Sciences)

   null (Ed.)

   Abstract This paper presents research results of biocidal effect of thermoplastic- polyester-elastomer (TPE-E) with incorporation of hybrid Ag/ZnO/SiO 2 NPs (silver/Zinc oxide/SiO 2 nanoparticles). These results were compared with various gamma-irradiated doses and processing techniques including extrusion, injection molding and compression molding. In all these processing techniques the TPE-E was mixed with mineral oil and Ag/ZnO/SiO 2 nanoparticles. The TPE-E nanocomposites were characterized by differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), Infrared FT spectroscopy (FTIR), surface enhanced Raman technique ( SERS), FESEM (Field emission scanning electron microscopy), Energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), TEM (transmission electronic microscopy) and antimicrobial test. Antibacterial activity against E. coli and S. aureus , are reported and these results showed potential application in health care products. 

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