Nb ₂ O ₅ microfibres with heterojunctions between amorphous and crystalline phases show improved photocatalytic activity in Nb ₂ O ₅ –benzylamine surface complex photocatalytic process.

ZnSiF₆-modified nano-sized HZSM-5 zeolites (NZ2, NZ3 and NZ4 catalysts) were prepared and investigated as catalysts for the conversion of methanol to aromatics.

Hierarchical nano-ZSM-5 zeolites (Z5-X) with different grain sizes were synthesized by varying amounts of 3-glycidoxypropyltrimethoxysilane (KH-560) in the hydrothermal synthesis strategy. Moreover, the conventional ZSM-5zeolite(Z5), which was prepared without KH-560, was used as the reference sample. The crystalline phases, morphologies, porous characteristics, Si/Al molar ratios and acidic properties of all fresh catalysts were characterized using the X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM), N₂ adsorption–desorption, inductively coupled plasma atomic emission spectroscopy (ICP) and temperature programmed desorption of ammonia (NH₃-TPD) techniques. Results show that the grain size and strong acid amount of zeolite decreased with the increasing amount of KH-560. The micropore surface areas and the corresponding volume of Z5-X changed less compared with Z5. Consequently, the high shape-selectivity of zeolite was preserved well under the addition of KH-560. However, the mesopore surface areas and the corresponding volume increased significantly with the increasing amount of KH-560. Benefiting from the abundant hierarchical structure, the Z5-X catalysts exhibited a larger coke capacity than the Z5 catalyst. The coke depositions of all the deactivated catalysts were characterized by the thermogravimetric technique (TG), and the results are indicative of the decreased average rate of coke deposition with an increasing amount of KH-560, which could result from the gradually reduced strong acid amount and the nano-sized crystallites. The catalytic performance of methanol-to-aromatics (MTA) indicates that the Z5-0.12 catalyst exhibited higher catalytic activity and selectivity of BTX as the reaction was prolonged, which could result from the synergistic effect among the proper strong acid amount, the smaller zeolite grain size, and the abundant hierarchical structure.

Cu can prevent carbon deposition on a surface due to weak adsorption, but it exhibits a high energy barrier to C–H bond activation, which means that it is not practical. Here, inspired by the catalytic properties of Pt and the strategy of single-atom alloys, a Pt₁Cu single-atom alloy (SAA) catalyst is built and studied. The primary goal is to understand the alloy's catalytic activity and coke-resistant properties during the partial oxidation of methane (POM) using density functional theory (DFT). Based on the wide application of Ni-based catalysts in POM, a parallel sample using a Pt₁Ni SAA catalyst is also studied. C–H bond activation and coke resistance are quantified by the activation energy barrier of CH₄ dissociation and the energy barrier of C₂ formation, respectively. It is shown that the Pt₁Cu SAA catalyst can promote activation of the C–H bond of CH₄, without affecting the excellent coke resistance. The first C–H cleavage is promoted by the introduction of a Pt single atom, and the activation energy barrier is 1.73 eV on the Cu(111) surface, while it is 1.16 eV on the Pt₁Cu(111) surface. The activation energy barrier of C₂ formation is 2.08 eV on the Cu(111) surface and 1.89 eV on the Pt₁Cu(111) surface. The properties of the Pt single-alloy Cu catalyst are obviously enhanced compared with reactions on commercial Ni-based catalysts. The activation energy barrier is 1.10 eV for CH₄ dissociation and 1.35 eV for C₂ formation with the Pt₁Ni SAA catalyst. Coke resistance is further elucidated by the method of changes of partial density of states (PDOS) and Mulliken charges in this work. The results on the electronic properties are consistent with the thermodynamic results. A reference strategy is provided in this work to promote the activation of the C–H bond and the coke-resistant performance during POM.

Selective conversion of syngas (CO/H₂) to ethanol is an attractive but challenging target.