Abstract Facile fabrication of well‐intergrown, oriented zeolite membranes with tunable chemical properties on commercially proven substrates is crucial to broadening their applications for separation and catalysis. Rationally determined electrostatic adsorption can enable the direct attachment of a b ‐oriented silicalite‐1 monolayer on a commercial porous ceramic substrate. Homoepitaxially oriented, well‐intergrown zeolite ZSM‐5 membranes with a tunable composition of Si/Al=25–∞ were obtained by secondary growth of the monolayer. Intercrystallite defects can be eliminated by using Na + as the mineralizer to promote lateral crystal growth and suppress surface nucleation in the direction of the straight channels, as evidenced by atomic force microscopy measurements. Water permeation testing shows tunable wettability from hydrophobic to highly hydrophilic, giving the potential for a wide range of applications.
Abstract Evolution of the Pd active centers in size and spatial distribution leads to an irreversible deactivation in many high-temperature catalytic processes. This research demonstrates the use of a defective alumina (Al 2 O 3-x ) as catalyst support to anchor Pd atoms and suppress the growth of Pd clusters in catalytic methane oxidation. A combination of operando spectroscopy and density functional theory (DFT) calculations provide insights into the evolution of Pd species and reveals distinct catalytic methane oxidation mechanisms on Pd single atoms, clusters, and nanoparticles (NPs). Among these Pd species, the cluster active centers are found to be the most favorable participants in methane oxidation due to their high dispersion, high content of Pd 2+ oxidation state, and resistance to deactivation by carbonates, bicarbonates, and water. The Pd/Al 2 O 3-x catalyst shows increased stability with respect to a Pd/Al 2 O 3 counterpart during simulated aging in alternating reducing and oxidizing conditions due to stronger interactions with the support. This study demonstrates that defect engineering of non-reducible supports can constrain the evolution of active centers, which holds promising potential for widespread utilization across diverse industrial catalytic processes, including various hydrogenation and oxidation reactions.
Iron and nitrogen co-doped hierarchically mesoporous carbon spheres (Fe–N–CS) were successfully prepared by using hierarchically mesoporous silica spheres as hard template.
ZnO/ZrO2 catalysts have shown excellent activity in the CO2 hydrogenation to methanol compared with single component counterparts, but the interaction between ZnO and ZrO2 is still poorly understood. In particular, the effect of the ZrO2 support phase (tetragonal vs. monoclinic) was not systematically explored. Here, we have synthesized ZnO/ZrO2 catalyst materials supported on tetragonal ZrO2 (ZnO/ZrO2-t) and monoclinic ZrO2 (ZnO/ZrO2-m), which resulted in the formation of different ZnOx species, consisting of sub-nanometer ZnO moieties and large-sized ZnO particles, respectively. ZnO/ZrO2-t exhibited much higher methanol selectivity (81 %) and methanol yield (1.25 mmol/g/h) compared with ZnO/ZrO2-m (39 % and 0.67 mmol/g/h). The difference in performance was attributed to the redox state and degree of dispersion of Zn, based on spectroscopy and microscopy results. Operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and in situ near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) showed that ZnO/ZrO2-t had a high density of ZnO-ZrO sites, which favored the formation of active HCOO* species and enhanced the yield and selectivity of methanol along the formate pathway. Operando UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS) together with Raman spectroscopy and high-angle angular dark field-scanning transmission electron microscopy (HAADF-STEM) combined with energy dispersive X-ray (EDX) analysis revealed that on ZnO/ZrO2-t, ZnO clusters were further dispersed during catalysis at 320 °C, forming high density of ZnO-ZrO sites, and facilitating the hydrogenation of CO2 to methanol, while larger ZnO particles on ZnO/ZrO2-m remained stable throughout the reaction. This study shows that the phase of ZrO2 supports can be used to control the dispersion of the active phase and lead to enhanced catalytic performance. We believe the insights are relevant for other methanol synthesis catalysts, where metal-support interactions are pivotal for catalyst activity and stability.
The One-Bead One-Compound (OBOC) library screening is an efficient technique for identifying targeting peptides. However, due to the relatively large bead size, it is challenging for the OBOC method to be applied for in vivo screening. Herein, we report an in vivo Localized Instillation Beads library (LIB) screening method to discover targeting peptides with the OBOC technique. Inspired by localized instillation, we constructed a cavity inside of a transplanted tumor of a mouse. Then, the OBOC heptapeptide library was injected and incubated inside the tumor cavity. After an efficient elution process, the retained beads were gathered, from which three MDA-MB-231 tumor-targeting heptapeptides were discovered. It was verified that the best peptide had 1.9-fold higher tumor accumulation than the commonly used targeting peptide RGD in vivo. Finally, two targeting proteins were discovered as potential targets of our targeting peptide to the MDA-MB-231 tumor. The in vivo LIB screening method expands the scope of OBOC peptide screening applications to discover targeting peptides in vivo feasibly and reliably.
To obtain a sustainable competitive advantage in the dynamic environment, it is necessary for Chinese high-tech enterprises to focus on their technology habitual domains in formulating ambidextrous innovation strategy. This study integrates technology habitual domain, exploratory innovation and exploitative innovation within a framework and explores the influence mechanism among them. Based on an in-depth case study on KTE, representing a high-tech enterprise in China, we have several findings. Firstly, we depict the evolution mechanism of technology habitual domain; secondly, we find that the high-tech enterprise’s technology habitual domain will cultivate and develop the firms’ dynamic capabilities; and thirdly, the expansion of technology habitual domain will promote exploitative innovation, while the transformation of technology habitual domain will promote exploratory innovation. These findings can be useful guidance for high-tech enterprises in China who are aiming to achieve ambidextrous innovation to better adapt to the turbulent environment, and thus achieving sustainability.
Characterizing materials at nanoscale resolution to provide new insights into structure property performance relationships continues to be a challenging research target due to the inherently low signal from small sample volumes, and is even more difficult for nonconductive materials, such as zeolites. Herein, we present the characterization of a single Cu-exchanged zeolite crystal, namely Cu-SSZ-13, used for NOX reduction in automotive emissions, that was subject to a simulated 135,000-mile aging. By correlating Atom Probe Tomography (APT), a single atom microscopy method, and Scanning Transmission X-ray Microscopy (STXM), which produces high spatial resolution X-ray Absorption Near Edge Spectroscopy (XANES) maps, we show that a spatially non-uniform proportion of the Al was removed from the zeolite framework. The techniques reveal that this degradation is heterogeneous at length scales from micrometers to tens of nanometers, providing complementary insight into the long-term deactivation of this catalyst system.
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