The incorporation of Ti in the MFI structure using a cheap and easy to handle source, the hexafluorotitanic acid, was successfully achieved without the formation of contaminant phases. The TS-1 samples with 1%, 2%, and 2.5% Ti present a linear increase in the cell parameters. This indicates that the Ti present in the solid is incorporated into the framework, and this is confirmed by infrared analysis. The TS-1 particles present morphology that is typical of the MFI structure. The UV-vis diffuse reflectance results indicate the existence of tetra- and hexacoordinated framework Ti species. Independent of Ti content, all of the samples present similar activity for the oxidation of cyclohexene using hydrogen peroxide as an oxidant agent. Also, a high selectivity for the formation of the corresponding epoxide is observed.
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http://dx.doi.org/10.1021/jp060703o | DOI Listing |
J Phys Chem C Nanomater Interfaces
January 2025
Center for Materials Science and Nanotechnology (SMN), Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, Oslo N-0315, Norway.
The flexibility of the H-ZSM-5 zeolite upon adsorption of selected coke precursors was investigated using both theoretical and experimental approaches. Four structural models with varying active site locations were analyzed through density functional theory (DFT) simulations to determine their responses to different types and quantities of aromatic molecules. Complementary experimental analysis was performed, allowing for a direct comparison with the theoretical findings, using thermogravimetric analysis (TGA), nitrogen adsorption (N adsorption), solid-state NMR, and X-ray diffraction (XRD).
View Article and Find Full Text PDFInt J Biol Macromol
January 2025
College of Food Science and Technology, Shanghai Ocean University, Shanghai 201306, China; Shanghai Aquatic Products Processing and Storage Engineering Technology Research Center, Shanghai 201306, China; National Experimental Teaching Demonstration Center for Food Science and Engineering (Shanghai Ocean University), Shanghai 201306, China. Electronic address:
Phenolic acid-chitosan derivatives have received extensive attention due to their greatly enhanced mechanical, antibacterial and antioxidant properties, especially in food preservation. The chitosan-gentianic acid (CS-g-GA) was prepared and its impact on myofibrillar proteins (MPs) in sea bass (Lateolabrax maculatus) during refrigerated storage was investigated in this study. Fish fillets were immersed in distilled water, CS, GA and CS-g-GA solutions, respectively, followed by an 18-day refrigerated storage.
View Article and Find Full Text PDFAcc Chem Res
January 2025
Key Lab of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China.
ConspectusFor chemical reactions with complex pathways, it is extremely difficult to adjust the catalytic performance. The previous strategies on this issue mainly focused on modifying the fine structures of the catalysts, including optimization of the geometric/electronic structure of the metal nanoparticles (NPs), regulation of the chemical composition/morphology of the supports, and/or adjustment of the metal-support interactions to modulate the reaction kinetics on the catalyst surface. Although significant advances have been achieved, the catalytic performance is still unsatisfactory.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Université de Caen Normandie, ENSICAEN, CNRS, LCS, 14000 Caen, France.
Germanium is known to occupy tetrahedral sites by substituting silicon in germanosilicate zeolites. In this study, we present pioneering findings regarding the synthesis of zeolites with an MFI structure (GeMFI) incorporating a high germanium amount (16% Ge). Remarkably, the germanium atoms feature a slight electron deficiency with respect to GeO, and the typical coordination number of 4, as usually reported for the germanosilicate zeolites, is exceeded, giving rise to Ge dimers in a double-bridge configuration.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Engineering Research Center of Advanced Rare-Earth Materials of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China.
Substituting the molecular metal complexes used in the industrial olefin hydroformylation process is of great significance in fundamental research and practical application. One of the major difficulties in replacing the classic molecular metal catalysts with supported metal catalysts is the low chemoselectivity and regioselectivity of the supported metal catalysts because of the lack of a well-defined coordination environment of the metal active sites. In this work, we have systematically studied the influences of key factors (crystallinity, alkali promoters, etc.
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