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1.
J Neurosci ; 44(13)2024 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-38302441

RESUMO

Ocular position drifts during gaze fixation are significantly less well understood than microsaccades. We recently identified a short-latency ocular position drift response, of ∼1 min arc amplitude, that is triggered within <100 ms by visual onsets. This systematic eye movement response is feature-tuned and seems to be coordinated with a simultaneous resetting of the saccadic system by visual stimuli. However, much remains to be learned about the drift response, especially for designing better-informed neurophysiological experiments unraveling its mechanistic substrates. Here we systematically tested multiple new feature tuning properties of drift responses. Using highly precise eye tracking in three male rhesus macaque monkeys, we found that drift responses still occur for tiny foveal visual stimuli. Moreover, the responses exhibit size tuning, scaling their amplitude (both up and down) as a function of stimulus size, and they also possess a monotonically increasing contrast sensitivity curve. Importantly, short-latency drift responses still occur for small peripheral visual targets, which additionally introduce spatially directed modulations in drift trajectories toward the appearing peripheral stimuli. Drift responses also remain predominantly upward even for stimuli exclusively located in the lower visual field and even when starting gaze position is upward. When we checked the timing of drift responses, we found it was better synchronized to stimulus-induced saccadic inhibition than to stimulus onset. These results, along with a suppression of drift response amplitudes by peristimulus saccades, suggest that drift responses reflect the rapid impacts of short-latency and feature-tuned visual neural activity on final oculomotor control circuitry in the brain.


Assuntos
Fixação Ocular , Visão Ocular , Animais , Masculino , Macaca mulatta , Movimentos Oculares , Movimentos Sacádicos , Percepção Visual/fisiologia
2.
Small ; 20(23): e2309831, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38133510

RESUMO

Non-invasive breath testing has gained increasing importance for early disease screening, spurring research into cheap sensors for detecting trace biomarkers such as ammonia. However, real-life deployment of ammonia sensors remains hindered by susceptibility to humidity-induced interference. The SnTe/SnSe heterojunction-based chemiresistive-type sensor demonstrates an excellent response/recovery to different concentrations of ammonia from 0.1 to 100 ppm at room temperature. The improved sensing properties of the heterojunctions-based sensors compared to single-phased SnTe or SnSe can be attributed to the stronger NH3 adsorptions, more Te vacancies, and hydrophobic surface induced by the formed SnTe/SnSe heterojunctions. The sensing mechanisms are investigated in detail by using in situ techniques such as diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS), Kelvin probe, and a.c. impedance spectroscopy together with the Density-Function-Theory calculations. The formed heterojunctions boost the overall charge transfer efficiency between the ammonia and the sensing materials, thus leading to the desirable sensing features as well, with excellent resistance to ambient humidities.

3.
Encephale ; 50(4): 427-435, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38311475

RESUMO

INTRODUCTION: Mindfulness meditation has gained prominence in somatic and psychiatric care in several countries including France. Studies have shown its effectiveness in various conditions, in particular the prevention of depressive relapses. However, there are criticisms and concerns about its potential links to Buddhism and spirituality, raising issues of secularism and sectarianism. This issue is particularly conflicting in France with regard its historical and political relationship with secularism. OBJECTIVES: This study aims to assess quantitative data regarding the impact of mindfulness meditation on spirituality and religiosity using quantitative validated scales. METHODS: A systematic review was conducted. PubMed was searched for relevant studies using keywords related to mindfulness and spirituality/religiosity scales. Four scales assessing spirituality were identified: FACIT-sp, INSPIRIT, DSES, and DUREL. Qualitative analysis determined if scale items pertained to spirituality or other topics considered by opponents to mindfulness as "at risk" for deviances or sectarian aberrations. Quantitative analysis assessed the effect size of changes in scale scores before and after mindfulness meditation interventions. RESULTS: Eighteen studies were analyzed, with varying scales and program durations including 1272 participants. Qualitative analysis showed that most scales contained items related to spirituality as well as "at risk" elements like religion and mysticism. Quantitative analysis revealed that a few studies reported significant increases in spirituality scores following mindfulness meditation, but the clinical relevance of these changes was questioned. In general, control groups had smaller score changes. INTERPRETATION: While some studies suggest a potential increase in spirituality due to mindfulness meditation, the clinical significance of these findings remains uncertain. Moreover, mindfulness meditation's ties to Buddhism are disputed, and its roots are intertwined with various psychotherapy traditions that incorporate spirituality. The role of secularism in psychotherapy is also debated in France, emphasizing the need for proper use and regulation policy rather than prohibition of mindfulness-based approaches. This study highlights the complexity of assessing the impact of mindfulness meditation on spirituality and religiosity. It suggests that a pragmatic approach focusing on risk and harm reduction may be more suitable than labeling the practice as "at risk". Further research is needed to clarify these issues in the specific cultural context of France.


Assuntos
Meditação , Atenção Plena , Espiritualidade , Humanos , Atenção Plena/métodos , Meditação/psicologia , Meditação/métodos , Budismo/psicologia , França
4.
Angew Chem Int Ed Engl ; 63(28): e202403093, 2024 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-38679566

RESUMO

The synthesis of covalent organic frameworks (COFs) at bulk scale require robust, straightforward, and cost-effective techniques. However, the traditional solvothermal synthetic methods of COFs suffer low scalability as well as requirement of sensitive reaction environment and multiday reaction time (2-10 days) which greatly restricts their practical application. Here, we report microwave assisted rapid and optimized synthesis of a donor-acceptor (D-A) based highly crystalline COF, TzPm-COF in second (10 sec) to minute (10 min) time scale. With increasing the reaction time from seconds to minutes crystallinity, porosity and morphological changes are observed for TzPm-COF. Owing to visible range light absorption, suitable band alignment, and low exciton binding energy (Eb=64.6 meV), TzPm-COF can efficaciously produce superoxide radical anion (O2 .-) after activating molecular oxygen (O2) which eventually drives aerobic photooxidative amidation reaction with high recyclability. This photocatalytic approach works well with a variety of substituted aromatic aldehydes having electron-withdrawing or donating groups and cyclic, acyclic, primary or secondary amines with moderate to high yield. Furthermore, catalytic mechanism was established by monitoring the real-time reaction progress through in situ diffuse reflectance infrared Fourier transform spectroscopic (DRIFTS) study.

5.
Zhongguo Yi Liao Qi Xie Za Zhi ; 48(4): 413-418, 2024 Jul 30.
Artigo em Zh | MEDLINE | ID: mdl-39155255

RESUMO

Nursing beds can be widely used in medical institutions and households to provide medical care for patients or disabled individuals. With the increasing demand for nursing, nursing beds are developing towards intelligence and comfort. In this study, the backrest lifting mechanism of nursing beds is selected as the research object. The standards for backrest angle adjustment and the basis for comfort judgment are reviewed, and the research on various adjustment configurations are sorted in order to provide assistance to relevant research institutions in understanding current technologies and assist users in making choices.


Assuntos
Leitos , Humanos , Desenho de Equipamento , Remoção , Movimentação e Reposicionamento de Pacientes/instrumentação
6.
Small ; 19(34): e2300945, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37093193

RESUMO

Identifying active sites of supported noble metal nanocatalysts remains challenging, since their size and shape undergo changes depending on the support, temperature, and gas mixture composition. Herein, the anharmonic infrared spectrum of adsorbed CO is simulated using density functional theory (DFT) to gain insight into the nature of Pd nanoparticles (NPs) supported on ceria. The authors systematically determine how the simulated infrared spectra are affected by CO coverage, NP size (0.5-1.5 nm), NP morphology (octahedral, icosahedral), and metal-support contact angle, by exploring a diversity of realistic models inspired by ab initio molecular dynamics. The simulated spectra are then used as a spectroscopic fingerprint to characterize nanoparticles in a real catalyst, by comparison with in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments. Truncated octahedral NPs with an acute Pd-ceria angle reproduce most of the measurements. In particular, the authors isolate features characteristic of CO adsorbed at the metal-support interface appearing at low frequencies, both seen in simulation and experiment. This work illustrates the strong need for realistic models to provide a robust description of the active sites, especially at the interface of supported metal nanocatalysts, which can be highly dynamic and evolve considerably during reaction.

7.
Environ Sci Technol ; 57(42): 16121-16130, 2023 10 24.
Artigo em Inglês | MEDLINE | ID: mdl-37842921

RESUMO

Ammonia-mediated selective catalytic reduction (NH3-SCR) is currently the key approach to abate nitrogen oxides (NOx) emitted from heavy-duty lean-burn vehicles. The state-of-art NH3-SCR catalysts, namely, copper ion-exchanged chabazite (Cu-CHA) zeolites, perform rather poorly at low temperatures (below 200 °C) and are thus incapable of eliminating effectively NOx emissions under cold-start conditions. Here, we demonstrate a significant promotion of low-temperature NOx reduction by reinforcing the dynamic motion of zeolite-confined Cu sites during NH3-SCR. Combining complex impedance-based in situ spectroscopy (IS) and extended density-functional tight-binding molecular dynamics simulation, we revealed an environment- and temperature-dependent nature of the dynamic Cu motion within the zeolite lattice. Further coupling in situ IS with infrared spectroscopy allows us to unravel the critical role of monovalent Cu in the overall Cu mobility at a molecular level. Based on these mechanistic understandings, we elicit a boost of NOx reduction below 200 °C by reinforcing the dynamic Cu motion in various Cu-zeolites (Cu-CHA, Cu-ZSM-5, Cu-Beta, etc.) via facile postsynthesis treatments, either in a reductive mixture at low temperatures (below 250 °C) or in a nonoxidative atmosphere at high temperatures (above 450 °C).


Assuntos
Zeolitas , Zeolitas/química , Cobre , Amônia/química , Óxidos de Nitrogênio/química , Temperatura , Catálise
8.
Environ Sci Technol ; 57(33): 12465-12475, 2023 08 22.
Artigo em Inglês | MEDLINE | ID: mdl-37556316

RESUMO

The low-temperature mechanism of chabazite-type small-pore Cu-SSZ-13 zeolite, a state-of-the-art catalyst for ammonia-assisted selective reduction (NH3-SCR) of toxic NOx pollutants from heavy-duty vehicles, remains a debate and needs to be clarified for further improvement of NH3-SCR performance. In this study, we established experimental protocols to follow the dynamic redox cycling (i.e., CuII ↔ CuI) of Cu sites in Cu-SSZ-13 during low-temperature NH3-SCR catalysis by in situ ultraviolet-visible spectroscopy and in situ infrared spectroscopy. Further integrating the in situ spectroscopic observations with time-dependent density functional theory calculations allows us to identify two cage-confined transient states, namely, the O2-bridged Cu dimers (i.e., µ-η2:η2-peroxodiamino dicopper) and the proximately paired, chemically nonbonded CuI(NH3)2 sites, and to confirm the CuI(NH3)2 pair as a precursor to the O2-bridged Cu dimer. Comparative transient experiments reveal a particularly high reactivity of the CuI(NH3)2 pairs for NO-to-N2 reduction at low temperatures. Our study demonstrates direct experimental evidence for the transient formation and high reactivity of proximately paired CuI sites under zeolite confinement and provides new insights into the monomeric-to-dimeric Cu transformation for completing the Cu redox cycle in low-temperature NH3-SCR catalysis over Cu-SSZ-13.


Assuntos
Zeolitas , Teoria da Densidade Funcional , Zeolitas/química , Oxirredução , Espectrofotometria Infravermelho , Catálise , Amônia/química
9.
Environ Sci Technol ; 57(37): 14091-14099, 2023 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-37643464

RESUMO

Wet denitrification is a promising approach to control nitrogen oxides (NOx) produced in fossil fuel combustion. Yet, the highly concentrated nitrite (NO2-) wastewater generated poses a major threat to the aqueous environment. Here, iridium nanoclusters (d = 1.63 nm) deposited on TiO2 were applied for NO2- reduction to ammonia (NRA), showing an exceptional NH4+ selectivity of 95% and a production rate of 20.51 mgN·L-1·h-1, which held significant potential for NO2- wastewater purification and ammonia resource recovery. Notably, an interesting non-first-order NO2- hydrogenation kinetics was observed, which was further confirmed to result from the competitive adsorption mechanism between H2 and NO2- over iridium. The NRA pathways on the Ir(111) surface were explored via density functional theory calculations with the NO2-* → NO* → HNO* → HNOH* → H2NOH* → NH2* → NH3* identified as the most energetically favorable pathway and the NO* → HNO* confirmed as the rate-determining step. In situ DRIFTS further experimentally verified the generation of HNO* intermediate during NO* hydrogenation on Ir(111). To verify NRA kinetics at varied NO2- concentrations or H2 pressures, a kinetic model was derived based on the Langmuir-Hinshelwood competitive adsorption mechanism. These findings provide mechanistic insights into the NRA pathways on Ir nanocatalysts, which will be beneficial for wet denitrification waste stream decontamination and valorization.


Assuntos
Amônia , Nitritos , Hidrogenação , Adsorção , Irídio , Dióxido de Nitrogênio
10.
Sensors (Basel) ; 23(1)2023 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-36617114

RESUMO

Developing new sensor fusion algorithms has become indispensable to tackle the daunting problem of GPS-aided micro aerial vehicle (MAV) localization in large-scale landscapes. Sensor fusion should guarantee high-accuracy estimation with the least amount of system delay. Towards this goal, we propose a linear optimal state estimation approach for the MAV to avoid complicated and high-latency calculations and an immediate metric-scale recovery paradigm that uses low-rate noisy GPS measurements when available. Our proposed strategy shows how the vision sensor can quickly bootstrap a pose that has been arbitrarily scaled and recovered from various drifts that affect vision-based algorithms. We can consider the camera as a "black-box" pose estimator thanks to our proposed optimization/filtering-based methodology. This maintains the sensor fusion algorithm's computational complexity and makes it suitable for MAV's long-term operations in expansive areas. Due to the limited global tracking and localization data from the GPS sensors, our proposal on MAV's localization solution considers the sensor measurement uncertainty constraints under such circumstances. Extensive quantitative and qualitative analyses utilizing real-world and large-scale MAV sequences demonstrate the higher performance of our technique in comparison to most recent state-of-the-art algorithms in terms of trajectory estimation accuracy and system latency.

11.
Molecules ; 28(4)2023 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-36838945

RESUMO

Pd-based catalysts are widely used in the oxidation of CH4 and have a significant impact on global warming. However, understanding their active sites remains controversial, because interconversion between Pd and PdO occurs consecutively during the reaction. Understanding the intrinsic active sites under reaction conditions is critical for developing highly active and selective catalysts. In this study, we demonstrated that partially oxidized palladium (PdOx) on the surface plays an important role for CH4 oxidation. Regardless of whether the initial state of Pd corresponds to oxides or metallic clusters, the topmost surface is PdOx, which is formed during CH4 oxidation. A quantitative analysis using CO titration, diffuse reflectance infrared Fourier-transform spectroscopy, X-ray diffraction, and scanning transmission electron microscopy demonstrated that a surface PdO layer was formed on top of the metallic Pd clusters during the CH4 oxidation reaction. Furthermore, the time-on-stream test of CH4 oxidation revealed that the presence of the PdO layer on top of the metallic Pd clusters improves the catalytic activity. Our periodic density functional theory (DFT) calculations with a PdOx slab and nanoparticle models aided the elucidation of the structure of the experimental PdO particles, as well as the experimental C-O bands. The DFT results also revealed the formation of a PdO layer on the metallic Pd clusters. This study helps achieve a fundamental understanding of the active sites of Pd and PdO for CH4 oxidation and provides insights into the development of active and durable Pd-based catalysts through molecular-level design.


Assuntos
Óxidos , Paládio , Domínio Catalítico , Oxirredução , Paládio/química
12.
Molecules ; 28(8)2023 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-37110744

RESUMO

Cu-doped manganese oxide (Cu-Mn2O4) prepared using aerosol decomposition was used as a CO oxidation catalyst. Cu was successfully doped into Mn2O4 due to their nitrate precursors having closed thermal decomposition properties, which ensured the atomic ratio of Cu/(Cu + Mn) in Cu-Mn2O4 close to that in their nitrate precursors. The 0.5Cu-Mn2O4 catalyst of 0.48 Cu/(Cu + Mn) atomic ratio had the best CO oxidation performance, with T50 and T90 as low as 48 and 69 °C, respectively. The 0.5Cu-Mn2O4 catalyst also had (1) a hollow sphere morphology, where the sphere wall was composed of a large number of nanospheres (about 10 nm), (2) the largest specific surface area and defects on the interfacing of the nanospheres, and (3) the highest Mn3+, Cu+, and Oads ratios, which facilitated oxygen vacancy formation, CO adsorption, and CO oxidation, respectively, yielding a synergetic effect on CO oxidation. DRIFTS-MS analysis results showed that terminal-type oxygen (M=O) and bridge-type oxygen (M-O-M) on 0.5Cu-Mn2O4 were reactive at a low temperature, resulting in-good low-temperature CO oxidation performance. Water could adsorb on 0.5Cu-Mn2O4 and inhibited M=O and M-O-M reaction with CO. Water could not inhibit O2 decomposition to M=O and M-O-M. The 0.5Cu-Mn2O4 catalyst had excellent water resistance at 150 °C, at which the influence of water (up to 5%) on CO oxidation could be completely eliminated.

13.
J Environ Sci (China) ; 127: 811-823, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36522108

RESUMO

La1-xCoO3-δ catalysts with different non-stoichiometry of lanthanum ions were synthesized by using the sol-gel method, and their catalytic performance in toluene combustion was investigated. The results showed that the catalytic activity and stability of A-site nonstoichiometric La1-xCoO3-δ were improved to a certain extent compared with pure LaCoO3 perovskite. Among them, the La0.9CoO3-δ catalyst gave the best catalytic performance for toluene oxidation. It achieved 90% toluene conversion at 205°C under the conditions of a WHSV (weight hourly space velocity) of 22,500 mL/(g·hr) and a 500 ppmV-toluene concentration. Various characterization techniques were used to investigate the relationship between the structure of these catalysts and their catalytic performance. It was found that the non-stoichiometric modification of the lanthanum ion at position A in LaCoO3 changed the surface element state of the catalyst and increased the oxygen vacancy content, thus, combined with improved reducibility, improving toluene degradation on the catalyst.

14.
J Environ Sci (China) ; 126: 445-458, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36503771

RESUMO

Series of Cu-USY zeolite catalyst with different Cu loading content were synthesized through simple impregnation method. The obtained catalysts were subjected to selective catalytic reduction of NOx with NH3 (NH3-SCR) performance evaluation, structural/chemical characterizations such as X-ray diffraction (XRD), N2 adsorption/desorption, H2 temperature-programmed reduction (H2-TPR), NH3 temperature-programmed desorption (NH3-TPD) as well as detailed in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments including CO adsorption, NH3 adsorption and NO+O2 in situ reactions. Results show that Cu-USY with proper Cu loading (in this work 5Cu-USY with 5 wt.% Cu) could be promising candidates with highly efficient NH3-SCR catalytic performance, relatively low byproduct formation and excellent hydrothermal stability, although its SO2 poisoning tolerability needs alleviation. Further characterizations reveal that such catalytic advantages can be attributed to both active cu species and surface acid centers evolution modulated by Cu loading. On one hand, Cu species in the super cages of zeolites increases with higher Cu content and being more conducive for NH3-SCR reactivity. On the other hand, higher Cu loading leads to depletion of Brønsted acid centers and simultaneous formation of abundant Lewis acid centers, which facilitates NH4NO3 reduction via NH3 adsorbed on Lewis acid centers, thus improving SCR reactivity. However, Cu over-introduction leads to formation of surface highly dispersed CuOx, causing unfavorable NH3 oxidation and inferior N2 selectivity.


Assuntos
Ácidos de Lewis , Zeolitas , Catálise , Adsorção , Espectrometria de Massas , Temperatura
15.
Angew Chem Int Ed Engl ; 62(29): e202303939, 2023 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-37212538

RESUMO

Cu/ZrO2 is a promising catalyst for the hydrogenation of CO2 to methanol. Reaction pathways involving formates or hydroxycarbonyls have been proposed. We show here that three different types of formates can be observed under reaction conditions at 220 °C and 3 bar, one being located on metallic Cu and two others being bound to ZrO2 . The surface concentrations of formates were determined through calibration curves and their reactivity measured during chemical transient experiments. The Cu-bound formate represented only about 7 % of surface formates, but exhibited a higher reactivity and was found to be the only formate that could account for all the production of methanol. Copper is thus not there only to activate H2 , but also bears other crucial intermediates. This work reemphasizes that fully quantitative IR analyses and transient methods are required to unravel the role of surface species.

16.
Angew Chem Int Ed Engl ; 62(46): e202305651, 2023 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-37612240

RESUMO

Tetrafluoromethane (CF4 ), the simplest perfluorocarbon (PFC), has the potential to exacerbate global warming. Catalytic hydrolysis is a viable method to degrade CF4 , but fluorine poisoning severely restricts both the catalytic performance and catalyst lifetime. In this study, Ga is introduced to effectively assists the defluorination of poisoned Al active sites, leading to highly efficient CF4 decomposition at 600 °C with a catalytic lifetime exceeding 1,000 hours. 27 Al and 71 Ga magic-angle spinning nuclear magnetic resonance spectroscopy (MAS NMR) showed that the introduced Ga exists as tetracoordinated Ga sites (GaIV ), which readily dissociate water to form Ga-OH. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density function theory (DFT) calculations confirmed that Ga-OH assists the defluorination of poisoned Al active sites via a dehydration-like process. As a result, the Ga/Al2 O3 catalyst achieved 100 % CF4 decomposition keeping an ultra-long catalytic lifetime and outperforming reported results. This work proposes a new approach for efficient and long-term CF4 decomposition by promoting the regeneration of active sites.

17.
Nanotechnology ; 34(4)2022 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-36260974

RESUMO

We use CeOx-TiO2hetero-interfaces generated on the surface of CeOx-TiO2hybrid oxide supporting powders to stabilize Au single-atoms (SAs) with excellent low-temperature activity toward CO oxidation. Based on intriguing density functional theory calculation results on the preferential formation of Au-SAs at the CeOx-TiO2interfaces and the high activity of Au-SAs toward the Mars-van Krevelen type CO oxidation, we synthesized a Au/CeOx-TiO2(ACT) catalyst with 0.05 wt.% of Au content. The Au-SAs stabilized at the CeOx-TiO2interfaces by electronic coupling between Au and Ce showed improved low-temperature CO oxidation activity than the conventional Au/TiO2control group catalyst. However, the light-off profile of ACT showed that the early activated Au-SAs are not vigorously participating in CO oxidation. The large portion of the positive effect on the overall catalytic activity from the low activation energy barrier of ACT was retarded by the negative impact from the decreasing active site density at high temperatures. We anticipate that the low-temperature activity and high-temperature stability of Au-SAs that stand against each other can be optimized by controlling the electronic coupling strength between Au-SAs and oxide clusters at the Au-oxide-TiO2interfaces. Our results show that atomic-precision interface modulation could fine-tune the catalytic activity and stability of Au-SAs.

18.
Angew Chem Int Ed Engl ; 61(23): e202200434, 2022 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-35303388

RESUMO

Aiming at knowledge-driven design of novel metal-ceria catalysts for automotive exhaust abatement, current efforts mostly pertain to the synthesis and understanding of well-defined systems. In contrast, technical catalysts are often heterogeneous in their metal speciation. Here, we unveiled rich structural dynamics of a conventional impregnated Pd/CeO2 catalyst during CO oxidation. In situ X-ray photoelectron spectroscopy and operando X-ray absorption spectroscopy revealed the presence of metallic and oxidic Pd states during the reaction. Using transient operando infrared spectroscopy, we probed the nature and reactivity of the surface intermediates involved in CO oxidation. We found that while low-temperature activity is associated with sub-oxidized and interfacial Pd sites, the reaction at elevated temperatures involves metallic Pd. These results highlight the utility of the multi-technique operando approach for establishing structure-activity relationships of technical catalysts.

19.
Angew Chem Int Ed Engl ; 61(12): e202113909, 2022 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-34845811

RESUMO

The efficient delivery of reactive and toxic gaseous reagents to organic reactions was studied using metal-organic frameworks (MOFs). The simultaneous cargo vehicle and catalytic capabilities of several MOFs were probed for the first time using the examples of aromatization, aminocarbonylation, and carbonylative Suzuki-Miyaura coupling reactions. These reactions highlight that MOFs can serve a dual role as a gas cargo vehicle and a catalyst, leading to product formation with yields similar to reactions employing pure gases. Furthermore, the MOFs can be recycled without sacrificing product yield, while simultaneously maintaining crystallinity. The reported findings were supported crystallographically and spectroscopically (e.g., diffuse reflectance infrared Fourier transform spectroscopy), foreshadowing a pathway for the development of multifunctional MOF-based reagent-catalyst cargo vessels for reactive gas reagents as an attractive alternative to the use of toxic pure gases or gas generators.

20.
Coord Chem Rev ; 426: 213544, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32981945

RESUMO

Progress in metal-organic frameworks (MOFs) has advanced from fundamental chemistry to engineering processes and applications, resulting in new industrial opportunities. The unique features of MOFs, such as their permanent porosity, high surface area, and structural flexibility, continue to draw industrial interest outside the traditional MOF field, both to solve existing challenges and to create new businesses. In this context, diverse research has been directed toward commercializing MOFs, but such studies have been performed according to a variety of individual goals. Therefore, there have been limited opportunities to share the challenges, goals, and findings with most of the MOF field. In this review, we examine the issues and demands for MOF commercialization and investigate recent advances in MOF process engineering and applications. Specifically, we discuss the criteria for MOF commercialization from the views of stability, producibility, regulations, and production cost. This review covers progress in the mass production and formation of MOFs along with future applications that are not currently well known but have high potential for new areas of MOF commercialization.

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