Successive Interfacial Reaction-Directed Synthesis of CeO₂@Au@CeO₂‑MnO₂ Environmental Catalyst with Sandwich Hollow Structure

Noble metal nanoparticle-based catalysts are widely used for the removal of hazardous materials. During the catalytic reactions, it is of particular importance for developing novel strategies to avoid the leaching or sintering of noble metal nanoparticles. Here, the 4-nitrophenol (4-NP) and CO, typical hazardous chemicals in industrial water and exhaust gases from vehicles, are studied for their removal using CeO₂@Au@CeO₂-MnO₂ catalyst. The sandwich hollow structure is achieved by means of successive interfacial redox reaction without any surfactants and without involving any surface modifications. Because of the synergistic interaction between Au nanoparticles and oxides, the as-prepared environmental catalyst exhibits remarkable activity toward the 4-NP reduction. Moreover, the sandwich structure inhibits the growth of the Au nanoparticles and the as-prepared catalyst still displays high activity toward CO oxidation even when the catalyst is treated at 600 °C

Design of Porous/Hollow Structured Ceria by Partial Thermal Decomposition of Ce-MOF and Selective Etching

Metal–organic frameworks (MOFs) have been widely used to prepare corresponding porous metal oxides via thermal treatment. However, high temperature treatment always leads to obtained metal oxides with a large crystallite size, thus decreasing their specific surface area. Different from the conventional complete thermal decomposition of MOFs, herein, using Ce-MOF as a demonstration, we choose partial thermal decomposition of MOF, followed by selective etching to prepare porous/hollow structured ceria because of the poor stability of Ce-MOF under acidic conditions. Compared with the ceria derived from complete thermal decomposition of Ce-MOF, the as-prepared ceria is demonstrated to be a good support for copper oxide species during the CO oxidation catalytic reaction. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and hydrogen temperature-programmed reduction (H₂-TPR) analysis revealed that the as-prepared ceria is favorable for strengthening the interaction between the ceria and loaded copper oxide species. This work is expected to open a new, simple avenue for the synthesis of metal oxides from MOFs via partial thermal decomposition

Self-Assembly of Hierarchically Porous ZSM-5/SBA-16 with Different Morphologies and Its High Isomerization Performance for Hydrodesulfurization of Dibenzothiophene and 4,6-Dimethyldibenzothiophene

ZSM-5/SBA-16 (ZS) composite materials with different morphologies were synthesized successfully. The series supports were utilized to prepare NiMo/ZS for dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) hydrodesulfurization (HDS) reactions. Series ZS supports and NiMo/ZS were well characterized to investigate their structure–property relationship. The NiMo/ZS catalyst (NiMo/ZS-3) with uniform morphology and well-ordered pore channels showed the maximum <i>k</i>_HDS and TOF values of DBT and 4,6-DMDBT HDS. The <i>k</i>_HDS value (13.9 × 10^–4 mol g^–1 h^–1) of DBT over NiMo/ZS-3 was more than 2 times greater than that over the reference NiMo/ZS-M catalyst (5.5 × 10^–4 mol g^–1 h^–1), 3 times greater than that over the NiMo/SBA-16 catalyst (4.4 × 10^–4 mol g^–1 h^–1), and almost 4 times greater than that over the NiMo/ZSM-5 catalyst (3.5 × 10^–4 mol g^–1 h^–1). Furthermore, the <i>k</i>_HDS value (8.4 × 10^–4 mol g^–1 h^–1) of 4,6-DMDBT over NiMo/ZS-3 was more than 3 times greater than that over the reference NiMo/ZS-M catalyst (2.8 × 10^–4 mol g^–1 h^–1), more than 4 times greater than that over the NiMo/SBA-16 catalyst (1.7 × 10^–4 mol g^–1 h^–1), and almost 5 times greater than that over the NiMo/ZSM-5 catalyst (1.6 × 10^–4 mol g^–1 h^–1). The superior DBT and 4,6-DMDBT HDS performances were assigned to the uniform morphology, well-ordered pore channels, and high B/L ratio of the NiMo/ZS-3 catalyst and the suitable dispersion of the MoS₂ active phases. HYD was the preferential route for DBT HDS, while ISO was the preferential route for 4,6-DMDBT HDS because of the high B/L ratio of NiMo/ZS-3. Moreover, the DBT and 4,6-DMDBT HDS reaction networks of the series NiMo/ZS are presented

Morphology Design of IRMOF‑3 Crystal by Coordination Modulation

A one-pot synthesis design on shape-controlled growth of Zn-based isoreticular metal–organic framework (i.e., IRMOF-3) was carried out in this work with the controllable crystal morphological evolution from simple cubes to several complex shapes. A new synthetic protocol was devised where poly­(vinylpyrrolidone) (PVP), noble metal source (AgNO₃), mixed solvents (<i>N</i>,<i>N</i>-dimethylformamide (DMF)–ethanol mixture) and tetramethylammonium bromide (TMAB) were mutually introduced to the reaction medium as surfactant, adjuvant, accelerator, and structure-directing agent (SDA), respectively. Meanwhile, the crystallization process was investigated by a series of time-dependent experiments. Indeed, the added modulators and crystallization time were able to regulate the growth and thus the morphology of the final products. The resulting homogeneous IRMOF-3-Ag-<i><b>n</b></i> materials with unique and novel crystal morphologies were characterized via scanning electron microscopy (SEM), X-ray powder diffraction (XRD), thermogravimetric and differential thermal analyses (TG-DTA), transmission electron microscopy (TEM), infrared spectrum (IR), and optical microscope characterizations. Various shapes of IRMOF-3-Ag-<i><b>n</b></i> crystals as sorbents for capturing dibenzothiophene (DBT) were evaluated. Among all the morphology-controlled samples, IRMOF-3-Ag-<b>5</b> with hollow sphere morphology was demonstrated to show the highest DBT capture capacity due to its unique morphology