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Tetrahydrofurfuryl alcohol (THFA) is an important raw material for the preparation of the furan-based compound. Herein, we successfully synthesized 2-methyl tetrahydrofuran (2-MTHF) for the first time from THFA (Ring-opening and ring-closing of THFA) by solvent-free technique. The Ag–CeOx/MCM-41 catalyst was synthesized by the impregnation method. N2 adsorption–desorption, HR-TEM, XRD, XPS, and Py-IR characterized the catalysts. The presence of the Ce4+/Ce3+ redox pair and Ag NPs (Ag0) on the surface of the Ag–CeOx/MCM-41 catalyst was verified. The synergistic action of Ag and Ce on the catalyst surface, the enrichment of the L acid, and a few B acid centers are the key factors for the selective oxidation of THFA to 2-MTHF. The results of the experiments showed that THFA was 100% conversion and 2-MTHF selectivity was 68.11% under the reaction conditions of 150 °C, 4 MPa O2 pressure, and 1 g catalyst. Our findings provide a highly efficient method for the preparation of 2-MTHF from THFA. [ABSTRACT FROM AUTHOR]

The trajectories detection of carven flow is estimated generally through the calculation of changes in various physical fields and the hydrogeological conditions. This paper uses inertial components to solve the trajectory of carven flow. Due to the characteristics and the complex movement attitude of the inertial components in the flow, the calculation error accumulate over time, even cover the true trajectory. Based on the characteristics of carven flow and inertial components, this paper proposes a new trajectory detection technology to obtain relatively accurate trajectory.

Nanocrystals offer a unique platform for tailoring the physicochemical properties of solid materials to enhance their performances in various applications. While most work on controlling their shapes revolves around symmetrical growth, the introduction of asymmetrical growth and thus symmetry breaking has also emerged as a powerful route to enrich metal nanocrystals with new shapes and complex morphologies as well as unprecedented properties and functionalities. The success of this route critically relies on our ability to lift the confinement on symmetry by the underlying unit cell of the crystal structure and/or the initial seed in a systematic manner. This Review aims to provide an account of recent progress in understanding and controlling asymmetrical growth and symmetry breaking in a colloidal synthesis of noble-metal nanocrystals. With a touch on both the nucleation and growth steps, we discuss a number of methods capable of generating seeds with diverse symmetry while achieving asymmetrical growth for mono-, bi-, and multimetallic systems. We then showcase a variety of symmetry-broken nanocrystals that have been reported, together with insights into their growth mechanisms. We also highlight their properties and applications and conclude with perspectives on future directions in developing this class of nanomaterials. It is hoped that the concepts and existing challenges outlined in this Review will drive further research into understanding and controlling the symmetry breaking process.

Non-noble transition metal complexes have attracted growing interest as efficient electrocatalysts for oxygen reduction reaction (ORR) while their activities still lack rational and effective regulation. Herein, we propose a d-π conjugation strategy for rough and fine tuning of ORR activity of TM-BTA (TM=Mn/Fe/Co/Ni/Cu, BTA=1,2,4,5-benzenetetramine) coordination polymers. By first-principle calculations, we elucidate that the strong d-π conjugation elevates the d xz /d yz orbitals of TM centers to enhance intermediate adsorption and strengthens the electronic modulation effect from substitute groups on ligands. Based on this strategy, Co-TABQ (tetramino benzoquinone) is found to approach the top of ORR activity volcano. The synthesized Co-TABQ with atomically distributed Co on carbon nanotubes exhibits a half-wave potential of 0.85 V and a specific current of 127 mA mg metal -1 at 0.8 V, outperforming the benchmark Pt/C. The high activity, low peroxide yield, and considerable durability of Co-BTA and Co-TABQ promise their application in oxygen electrocatalysis. This study provides mechanistic insight into the rational design of transition metal complex catalysts., (© 2021 Wiley-VCH GmbH.)