Direct Catalytic Conversion of Biomass-Derived Furan and Ethanol to Ethylbenzene

Herein, we report a synthetic strategy to convert biomass-derived unsubstituted furan to aromatics at high selectivity, especially to ethylbenzene via alkylation/Diels–Alder cycloaddition using ethanol, while greatly reducing the formation of the main side product, benzofuran, over zeolite catalysts. Using synchrotron X-ray powder diffraction and first-principles calculations, it is shown that the above methodology favors the formation of aromatic products due to ready alkylation of furan by the first ethanol molecule, followed by Diels–Alder cycloaddition with ethylene derived from the second ethanol molecule on a Brønsted acid site in a one-pot synthesis. This gives a double-promoting effect: an alkyl substituent(s) on furan creates steric hindrance to inhibit self-coupling to benzofuran while an alkylated furan (diene) undergoes a Diels–Alder reaction more favorably due to higher HOMO energy

Selective Wrapping of Few-Walled Carbon Nanotubes by a Serpent-Like Heterobimetallic Coordination Polymer

In this work, selective interactions between the constituents of the composite CNT@MnCu (<b>2</b>) prepared using carbon nonotubes (CNTs) (<b>1</b>) and the heterobimetallic chain [MnCu­(opba)]_<i>n</i> (MnCu), opba = <i>o</i>-phenylenebis­(oxamate), were studied mainly by resonance Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM). An apparent interaction between CNTs and MnCu complex with the wrapping of the former by the heterobimetallic complex was observed in the microscopy images. The resonance Raman data suggest that the interations between MnCu complex and the CNTs are selective, occurring mainly with metallic CNTs independently of the diameter and excitation energy. However, for semiconducting CNTs, these interactions solely occur with tubes having diameters higher than ca. 1.47 nm

CO₂ Hydrogenation to Methanol over Catalysts Derived from Single Cationic Layer CuZnGa LDH Precursors

Ultrathin (1–3 cationic-layers) (CuZn)_1–<i>x</i>Ga_<i>x</i>-CO₃ layered double hydroxide (LDH) nanosheets were synthesized following the aqueous miscible organic solvent treatment (AMOST) method and applied as catalyst precursors for methanol production from CO₂ hydrogenation. It is found that, upon reduction, the aqueous miscible organic solvent treated LDH (AMO-LDH) samples above a critical Ga³⁺ composition give consistently and significantly higher Cu surface areas and dispersions than the catalysts prepared from conventional hydroxyl-carbonate phases. Owing to the distinctive local steric and electrostatic stabilization of the ultrathin LDH structure, the newly formed active Cu­(Zn) metal atoms can be stably embedded in the cationic layers, exerting an enhancement to the catalytic reaction. The best catalyst in this study displayed methanol productivity with a space-time yield of 0.6 g_MeOH·g_cat^–1 h^–1 under typical reaction conditions, which, as far as we are aware, is higher than most reported Cu-based catalysts in the literature