Author
Yifei Chen
Other affiliations: Civil Aviation University of China
Bio: Yifei Chen is an academic researcher from Tianjin University. The author has contributed to research in topics: Catalysis & Adsorption. The author has an hindex of 16, co-authored 48 publications receiving 733 citations. Previous affiliations of Yifei Chen include Civil Aviation University of China.
Papers
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TL;DR: It is found that MOF-74(Mn, Co) exhibits the capability for selective catalytic reduction (SCR) of NOx at low temperatures and showed that MOf-74 could be used prospectively as deNOx catalyst.
Abstract: In this work, Mn-MOF-74 with hollow spherical structure and Co-MOF-74 with petal-like shape have been prepared successfully via the hydrothermal method. The catalysts were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry–mass spectrum analysis (TG-MS), N2 adsorption/desorption, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). It is found that MOF-74(Mn, Co) exhibits the capability for selective catalytic reduction (SCR) of NOx at low temperatures. Both experimental (temperature-programmed desorption, TPD) and computational methods have shown that Co-MOF-74 and Mn-MOF-74 owned high adsorption and activation abilities for NO and NH3. The catalytic activities of Mn-MOF-74 and Co-MOF-74 for low-temperature denitrification (deNOx) in the presence of NH3 were 99% at 220 °C and 70% at 210 °C, respectively. It is found that the coordinatively unsaturated metal sites (CUSs) in M-MOF-74 (M = Mn and Co) played important role...
188 citations
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TL;DR: In this paper, the effect of the synthetic temperature on the structure and low temperature NH3-SCR catalytic performance of Co-MOF-74 was systematically investigated, and the highest catalytic activity was obtained at 200°C under the optimal synthesis temperature, which was attributed to the combination of special morphology, the highest specific surface area and Co content.
69 citations
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TL;DR: In this paper, the physicochemical properties of catalyst samples were characterized by multiple techniques, such as N2 adsorption-desorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature-programmed desorption (TPD), and Xray photoelectron spectroscopy (XPS).
Abstract: The novel Cu-MOF-74 materials were synthesized with various cosolvents at different temperatures by a solvent-thermal method and then developed as NO removal catalysts for low temperature selective catalytic reduction (SCR) with NH3. The physicochemical properties of catalyst samples were characterized by multiple techniques, such as N2 adsorption–desorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature-programmed desorption (TPD), and X-ray photoelectron spectroscopy (XPS). The effects of cosolvent on the catalyst performances were systematically investigated. It was found that Cu-MOF-74-iso-80 catalyst showed the highest NH3-SCR activity, giving 97.8% NO conversion and 100% N2 selectivity at 230 °C. BET test results suggested that Cu-MOF-74 showed a larger specific surface area. Stronger NH3 adsorption ability was found, which could be beneficial for SCR at low temperature. The catalyst also showed better water resistance performance. The adverse effect of H2O added intermitt...
64 citations
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TL;DR: In this article, a series of Pd/In2O3/SBA-15 catalysts were prepared by the citric acid method and the DFT simulation and catalyst characterization including the N2 adsorption, XRD, H2-TPR, TEM, XPS, and CO2 TPD were applied.
Abstract: The catalytic hydrogenation of CO2 to methanol has been regarded as the one of the most economical and effective ways to reduce CO2 emissions. It can also provide a feasible idea for solving the energy crisis. In this paper, a series of Pd/In2O3/SBA-15 catalysts were prepared by the citric acid method. The DFT simulation and catalyst characterization including the N2 adsorption, XRD, H2-TPR, TEM, XPS and CO2-TPD were applied. The results showed that the as-prepared Pd/In2O3/SBA-15 catalysts exhibited superior catalytic activity with 83.9% methanol selectivity and 12.6% CO2 conversion, corresponding to a STY of 1.1 × 10-2 mol·h-1·gcat-1 under reaction conditions of 260 °C, 5 Mpa and 15,000 cm3 h-1·gcat-1. It is suggested that the synergetic effect of H2 dissociation on Pd species and CO2 activation on In2O3 promoted the high efficiency conversion of CO2 to methanol.
50 citations
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TL;DR: In this paper, UiO-66 was employed as the support for palladium nanoparticles via a sol-gel method to enhance the activity of CO2 methanation, and the physicalchemical properties of as-prepared catalysts were characterized using N2 adsorption-desorption, X-ray diffraction (XRD), transmission electron microscope (TEM), temperature programmed desorption (TPD), temperature-programmed reduction (TPR), thermo-gravimetric analysis (TGA), Fourier transform infrared (FTIR) spect
Abstract: Carbon dioxide methanation is of great importance for both environment and energy because of the reduction of carbon dioxide emissions and the utilization of carbon source. In this work, UiO-66 was employed as the support for palladium nanoparticles via a sol-gel method to enhance the activity of CO2 methanation. The physical-chemical properties of as-prepared catalysts were characterized using N2 adsorption-desorption, X-ray diffraction (XRD), transmission electron microscope (TEM), temperature programmed desorption (TPD), temperature programmed reduction (TPR), thermo-gravimetric analysis (TGA), Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that there was a synergistic effect between UiO-66 and supported Pd. CO2 could be activated in UiO-66 via its Zr6O4(OH)4 nods, while H2 molecules were dissociated at Pd for further hydrogenation of activated CO2. As a result, the catalyst with a Pd loading of 6 wt.% exhibited a high activity with 56.0% of CO2 conversion and 97.3% of CH4 selectivity, corresponding to a STY of 856 g·h−1·kgcat−1 at 4 MPa and 340 °C.
45 citations
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TL;DR: This review summarizes the latest SCR reaction mechanisms and emerging poison-resistant mechanisms in the beginning and subsequently gives a comprehensive overview of newly developed SCR catalysts, including metal oxide catalysts ranging from VOx, MnOx, CeO2, and Fe2O3 to CuO based catalysts.
Abstract: Selective catalytic reduction with NH3 (NH3-SCR) is the most efficient technology to reduce the emission of nitrogen oxides (NOx) from coal-fired industries, diesel engines, etc. Although V2O5-WO3(MoO3)/TiO2 and CHA structured zeolite catalysts have been utilized in commercial applications, the increasing requirements for broad working temperature window, strong SO2/alkali/heavy metal-resistance, and high hydrothermal stability have stimulated the development of new-type NH3-SCR catalysts. This review summarizes the latest SCR reaction mechanisms and emerging poison-resistant mechanisms in the beginning and subsequently gives a comprehensive overview of newly developed SCR catalysts, including metal oxide catalysts ranging from VOx, MnOx, CeO2, and Fe2O3 to CuO based catalysts; acidic compound catalysts containing vanadate, phosphate and sulfate catalysts; ion exchanged zeolite catalysts such as Fe, Cu, Mn, etc. exchanged zeolite catalysts; monolith catalysts including extruded, washcoated, and metal-mesh/foam-based monolith catalysts. The challenges and opportunities for each type of catalysts are proposed while the effective strategies are summarized for enhancing the acidity/redox circle and poison-resistance through modification, creating novel nanostructures, exposing specific crystalline planes, constructing protective/sacrificial sites, etc. Some suggestions are given about future research directions that efforts should be made in. Hopefully, this review can bridge the gap between newly developed catalysts and practical requirements to realize their commercial applications in the near future.
800 citations
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TL;DR: This paper reviews recent experimental and computational work pertaining to the capture of several industrially-relevant toxic chemicals, including NH3, SO2, NO2, H2S, and some volatile organic compounds, with particular emphasis on the challenging issue of designing materials that selectively adsorb these chemicals in the presence of water.
Abstract: Owing to the vast diversity of linkers, nodes, and topologies, metal–organic frameworks can be tailored for specific tasks, such as chemical separations or catalysis. Accordingly, these materials have attracted significant interest for capture and/or detoxification of toxic industrial chemicals and chemical warfare agents. In this paper, we review recent experimental and computational work pertaining to the capture of several industrially-relevant toxic chemicals, including NH3, SO2, NO2, H2S, and some volatile organic compounds, with particular emphasis on the challenging issue of designing materials that selectively adsorb these chemicals in the presence of water. We also examine recent research on the capture and catalytic degradation of chemical warfare agents such as sarin and sulfur mustard using metal–organic frameworks.
642 citations
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TL;DR: A comprehensive overview of the recent advances in energy-efficient CO2 conversion, especially focusing on structure-activity relationship, is provided as well as the importance of combining catalytic measurements, in situ characterization, and theoretical studies in understanding reaction mechanisms and identifying key descriptors for designing improved catalysts.
Abstract: The utilization of fossil fuels has enabled an unprecedented era of prosperity and advancement of well-being for human society. However, the associated increase in anthropogenic carbon dioxide (CO2) emissions can negatively affect global temperatures and ocean acidity. Moreover, fossil fuels are a limited resource and their depletion will ultimately force one to seek alternative carbon sources to maintain a sustainable economy. Converting CO2 into value-added chemicals and fuels, using renewable energy, is one of the promising approaches in this regard. Major advances in energy-efficient CO2 conversion can potentially alleviate CO2 emissions, reduce the dependence on nonrenewable resources, and minimize the environmental impacts from the portions of fossil fuels displaced. Methanol (CH3OH) is an important chemical feedstock and can be used as a fuel for internal combustion engines and fuel cells, as well as a platform molecule for the production of chemicals and fuels. As one of the promising approaches, thermocatalytic CO2 hydrogenation to CH3OH via heterogeneous catalysis has attracted great attention in the past decades. Major progress has been made in the development of various catalysts including metals, metal oxides, and intermetallic compounds. In addition, efforts are also put forth to define catalyst structures in nanoscale by taking advantage of nanostructured materials, which enables the tuning of the catalyst composition and modulation of surface structures and potentially endows more promising catalytic performance in comparison to the bulk materials prepared by traditional methods. Despite these achievements, significant challenges still exist in developing robust catalysts with good catalytic performance and long-term stability. In this review, we will provide a comprehensive overview of the recent advances in this area, especially focusing on structure-activity relationship, as well as the importance of combining catalytic measurements, in situ characterization, and theoretical studies in understanding reaction mechanisms and identifying key descriptors for designing improved catalysts.
639 citations
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TL;DR: This review overviews the recent developments of catalysis at single metal sites in MOF-based materials with emphasis on their structures and applications for thermocatalysis, electrocatalysis, and photocatalysis.
Abstract: Metal-organic frameworks (MOFs) are a class of distinctive porous crystalline materials constructed by metal ions/clusters and organic linkers. Owing to their structural diversity, functional adjustability, and high surface area, different types of MOF-based single metal sites are well exploited, including coordinately unsaturated metal sites from metal nodes and metallolinkers, as well as active metal species immobilized to MOFs. Furthermore, controllable thermal transformation of MOFs can upgrade them to nanomaterials functionalized with active single-atom catalysts (SACs). These unique features of MOFs and their derivatives enable them to serve as a highly versatile platform for catalysis, which has actually been becoming a rapidly developing interdisciplinary research area. In this review, we overview the recent developments of catalysis at single metal sites in MOF-based materials with emphasis on their structures and applications for thermocatalysis, electrocatalysis, and photocatalysis. We also compare the results and summarize the major insights gained from the works in this review, providing the challenges and prospects in this emerging field.
571 citations
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TL;DR: In this paper, it was shown that ZnO samples can be magnetic even without transition-metal doping and also suggests that introducing Zn vacancy is a natural and an effective way to fabricate magnetic ZNO nanostructures.
Abstract: Extensive calculations based on density functional theory have been carried out to understand the origin of magnetism in undoped ZnO thin films as found in recent experiments. The observed magnetism is confirmed to be due to Zn, instead of O, vacancy. The main source of the magnetic moment, however, arises from the unpaired 2p electrons at O sites surrounding the Zn vacancy with each nearest-neighbor O atom carrying a magnetic moment ranging from 0.490 to 0.740 B. Moreover, the study of vacancy-vacancy interactions indicates that in the ground state, the magnetic moments induced by Zn vacancies prefer to ferromagnetically couple with the antiferromagnetic state lying 44 meV higher in energy. Since this is larger than the thermal energy at room temperature, the ferromagnetic state can be stable against thermal fluctuations. Calculations and discussions are also extended to ZnO nanowires that have larger surface to volume ratio. Here, the Zn vacancies are found to lead to the ferromagnetic state too. The present theoretical study not only demonstrates that ZnO samples can be magnetic even without transition-metal doping but also suggests that introducing Zn vacancy is a natural and an effective way to fabricate magnetic ZnO nanostructures. In addition, vacancy mediated magnetic ZnO nanostructures may have certain advantages over transition-metal doped systems in biomedical applications.
357 citations