Silica-assisted mesoporous Co@Carbon nanoplates derived from ZIF-67 crystals and their enhanced catalytic activity

Promotion of Au nanoparticles on carbon frameworks for alkali-free aerobic oxidation of benzyl alcohol

We synthesized a series of modified Co-ZIF-67 materials with tunable morphology to support fine Au nanoparticles for the alkali-free aerobic oxidation of benzyl alcohol. Structure promotion was performed using Stöber silica as a hard template, which was subsequently removed by NaOH etching before gold immobilization. The texture structure of Au/(Si)C was greatly improved with increasing surface area and volume. CoOx was simultaneously introduced into the carbon shell from the Co-ZIF-67 precursor, which consequently facilitated the specific Au-support interaction via bimetallic synergy. XRD, XPS, and TEM images demonstrated the redispersion of both Au and CoOx as well as the electronic delivery between metals. Analysis of the chemical and surface composition suggested a surface rich in Auδ+ with abundant lattice oxygen contributed by CoOx in the final Au/(Si)C, which improved the transformation rate of benzyl alcohol even in an alkali-free condition. Au/(Si)C with finely dispersed Au particles showed excellent catalytic performance in the alkali-free environment, with 89.3% benzyl conversion and 74.5% benzaldehyde yield under very mild conditions.

Fe Nanoparticle Size Control of the Fe-MOF-Derived Catalyst Using a Solvothermal Method: Effect on FTS Activity and Olefin Production

The design of a highly active Fe-supported catalyst with the optimum particle and pore size, dispersion, loading, and stability is essential for obtaining the desired product selectivity. This study employed a solvothermal method to prepare two Fe-MIL-88B metal-organic framework (MOF)-derived catalysts using triethylamine (TEA) or NaOH as deprotonation catalysts. The catalysts were analyzed using X-ray diffraction, N2-physisorption, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, H2 temperature-programed reduction, and thermogravimetric analysis and were evaluated for the Fischer-Tropsch synthesis performance. It was evident that the catalyst preparation in the presence of TEA produces a higher MOF yield and smaller crystal size than those produced using NaOH. The pyrolysis of MOFs yielded catalysts with different Fe particle sizes of 6 and 35 nm for the preparation in the presence of TEA and NaOH, respectively. Also, both types of catalysts exhibited a high Fe loading (50%) and good stability after 100 h reaction time. The smaller particle size TEA catalyst showed higher activity and higher olefin yield, with 94% CO conversion and a higher olefin yield of 24% at a lower reaction temperature of 280 °C and 20 bar at H2/CO = 1. Moreover, the smaller particle size TEA catalyst exhibited higher Fe time yield and CH4 selectivity but with lower chain growth probability (α) and C5+ selectivity.

Development of a Ba–CoCe catalyst for the efficient and stable decomposition of ammonia

CO_x-free hydrogen production; cobalt-based catalysts for ammonia decomposition; cerium–barium promoter in cobalt catalysts.

Engineering magnetic N-doped porous carbon with super-high ciprofloxacin adsorption capacity and wide pH adaptability

We report a high performance magnetic N-doped nanoporous carbon (MNPC) adsorbent synthesized by a simple single-step pyrolysis protocol. Grinding the mixture of ZnO nanoparticles, cobalt hydroxide and 2-methylimidazole produced Zn/Co-ZIFs that were converted into MNPC following subsequent pyrolysis in N₂ atmosphere. The optimized MNPC-700-0.4 adsorbent, obtained at 700 °C with Co/(Zn + Co) molar ratio of 0.4, is featured with super-high ciprofloxacin (CIP) adsorption capacity of 1563.7 mg g^-1 at 25 °C, fast adsorption dynamics (1.5 h of adsorption equilibrium time), wide pH adaptability (almost unchanged CIP adsorption capacity in pH 4-10), and good magnetic property. The magnetic property and CIP adsorption performance can be easily regulated by modulating the molar ratio of Co/(Zn + Co) and the pyrolysis temperature. The optimal MNPC-700-0.4 was chosen to explore adsorption kinetics and isotherm. The effects of pH, ionic strength and humic acid on CIP adsorption were investigated. CIP adsorption obeyed pseudo-second-order kinetics and well fitted the Langmuir adsorption model. The favorable textural properties (high surface area and pore volume), riched nitrogen structure and large amounts of defects endow the MNPC-700-0.4 lots of sites for CIP adsorption. The CIP adsorption onto MNPC-700-0.4 was mainly controlled by the electrostatic interaction, hydrophobic interaction, π-π stacking and hydrogen bond.