Cascade Performance of Nitroarenes with Alcohols Boosted by a Hollow Flying Saucer-Shaped Ni-Al2O3 Catalyst via a MOF-Templated Strategy Induced by the Kirkendall Effect

Catalysts with an open hollow structure can enhance the mass transfer capability of the catalyst during the reaction process, thereby further improving the catalytic performance. In this work, uniform and monodisperse flying-squircher-shaped Al-MOFs were synthesized via a solvothermal method. Furthermore, a hollow structure Al2O3-supported metallic Ni catalyst (termed Ni-Al2O3-HFA) was synthesized via the Kirkendall effect for the hydrogenation-alkylation cascade reaction by employing as-synthesized Al-MOFs as a carrier for impregnation of Ni(NO3)2·6H2O through further calcination and reduction. Various characterizations (e.g., XRD, HADDF-STEM, H2-TPR) were conducted to reveal the superior performance of the developed Ni-Al2O3-HFA catalyst compared to Ni/Al2O3-IWI (Al2O3 obtained from calcination of Al-MOFs) in cascade reaction between nitroarenes and alcohols. We hope to use the MOF template method via the Kirkendall effect to prepare hollow structure nanocatalysts, which can provide a guideline for the preparation of other hollow materials.

Mechanistic Insights into a Co(II)-Coordinated "Free" Metal Site of 2D Zinc-Based MOFs for β-Alkylation of Secondary Alcohols with Primary Alcohols

Through in-depth study of the properties and reaction mechanisms of catalysts, it is possible to better optimize catalytic systems and improve reaction efficiency and selectivity. This remains one of the challenges in the field of catalysis. Therefore, the research and design of catalysts play crucial roles in understanding and optimizing catalytic reaction mechanisms. A robust 2D zinc-based MOFs (Zn-HA) supported Co(II) ion catalyst (Zn-HA@Co) has been designed and synthesized via a coordination-assisted strategy for β-alkylation of secondary alcohols with primary alcohols. The characterization demonstrated that the anchoring of Co(II) on Zn-HA via coordination could efficiently enhance the Co(II) ion dispersity and interaction between Co(II) and Zn-HA MOFs. Importantly, the density functional theory results have provided mechanistic insights into the energy of the HOMO and LUMO of the Zn-HA@Co catalyst as well as the energy change of the entire process after interacting with the reactants and the specific energy changes of each orbital. The synthesized Zn-HA@Co MOFs effectively lower the energy barrier of the catalytic reaction process. We expect that our research and design of catalysts will serve as valuable guideline for understanding and optimizing catalytic reaction mechanisms.

Effect of Pyrolysis Conditions on the MOFs-Derived Zinc-Based Catalysts in Acetylene Acetoxylation

The preparation method and calcination temperature of metal-organic framework (MOFs)-derived materials are critical factors affecting catalytic performance. In this work, the preparation conditions of MOFS precursors were optimized, and zinc-based catalysts with different activities (MOF5-700, MOF5-750, and MOF5-800) were obtained by pyrolysis of MOFS precursors under nitrogen, which were then applied to an acetylene acetoxylation reaction system. According to the results, the conversion rate of acetic acid under catalysis was significantly different. (MOF5-700 (48%), MOF5-750 (62%), and MOF5-800 (22%)). Comparing the activity of the catalyst with the industrial catalyst Zn(OAc)2/AC (20%), MOF5-750 showed higher activity, and the acetic acid conversion rate remained around 60% after 50 h of stability testing. By characterization analysis, MOFs-derived materials were obtained after proper temperature pyrolysis. They have high mesoporous content, defects, and oxygen-containing functional groups and can maintain a good crystal structure, greatly reducing the loss of active components. This is the main reason for the good performance of the MOF5-750 catalyst in acetylene acetoxylation. Thus, the preparation conditions and favorable pyrolysis temperature of MOF derivative catalysts play a key role in the catalytic performance of acetylene acetoxylation.

Nanocarbon-based catalysts for selective nitroaromatic hydrogenation: A mini review

Selective hydrogenation of nitroaromatics to the corresponding anilines is a key topic for research in fine chemical industrial fields. Nanocarbon materials with good chemical stability, high electrical conductivity, and good mechanical performance have been regarded as promising candidates in the catalytic field, and have shown a wide range of applications in recent years. Controllable synthesis on the structure, morphology, and active sites of nanocarbon-based catalysts is vital to the development of highly efficient catalysts. In this mini-review, we summarize the recent progresses of nanocarbon materials by focusing on the synthesis approaches and their corresponding nanostructures, including carbon nanofibers, carbon nanotubes, graphene, porous carbon, carbon spheres, and metal organic framework-derived carbon materials. The design and catalytic performance of these nanocarbon materials have been systematically discussed. Finally, the emerging challenges and future prospective for developing advanced nanocarbon-based catalysts are outlined.