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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]

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 dxz/dyz 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 mgmetal−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. [ABSTRACT FROM AUTHOR]

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 dxz/dyz 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 mgmetal−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. [ABSTRACT FROM AUTHOR]

In this article, a novel chromium-free passivation agent contained sodium molybdate, sodium citrate, sodium phosphate, tannin, 1-hydroxyethylidene-1, 1-diphosphonic acid (HEDP) and cobalt nitrate was prepared. The component content of the chromium-free passivation agent was firstly determined by using the single variable method, and then optimized by the orthogonal array method. The results indicated that the optimal content of the passivation agent are sodium molybdate 15 g/L, sodium citrate 15 g/L, sodium phosphate 25 g/L, tannin 13 g/L, HEDP 14 ml/L and cobalt nitrate 11 g/L. In the neutral salt spray test, the corrosion life of the as-prepared passivation coatings can reach 46 h, implying the potential commercial application of this chromium-free passivation agent. [ABSTRACT FROM AUTHOR]