Explosive Decomposition of a Melamine-Cyanuric Acid Supramolecular Assembly for Fabricating Defect-Rich Nitrogen-Doped Carbon Nanotubes with Significantly Promoted Catalysis

Plastering Sponge with Nanocarbon-Containing Slurry to Construct Mechanically Robust Macroporous Monolithic Catalysts for Direct Dehydrogenation of Ethylbenzene

Nanocarbons have shown great potential as a sustainable alternative to metal catalysts, but their powder form limits their industrial applications. The preparation of nanocarbon-based monolithic catalysts is a practical approach for overcoming the resulting pressure drop associated with their powder form. In our previous work, a ploycation-mediated approach was used to successfully prepare nanocarbon-containing monoliths. Unfortunately, because there are no macropores in the monolith, it needs to be crashed into millimeter-sized particles before application. Therefore, developing a facile method for preparing mechanically robust nanocarbon-based macroporous monolithic catalysts is vital but still challenging. Herein, evoked by swallows building their nests, we report an approach for successfully preparing a mechanically robust nanodiamond-based macroporous monolith catalyst by plastering melamine sponge (MS) with a slurry composed of nanodiamonds (NDs) and poly(imidazolium-methylene) chloride (PImM) followed by an annealing process. The macroporous monolith catalyst (ND/NC_MS-NC_PImM) containing NDs well dispersed in N-doped carbon is mechanically robust with enriched macroscopic pores. It exhibits outstanding catalysis toward ethylbenzene to styrene through a direct dehydrogenation reaction with a high styrene rate in a steady state (5.50 mmol g^-1 h^-1) and high styrene selectivity (99.5%). ND/NC_MS-NC_PImM shows much higher activity than powder ND by 1.9 fold. In addition, this work solves the significant problem of large pressure drop encountered with conventional powdered nanocarbon catalysts in the flow reactor. This work not only creates an excellent nanodiamond-based macroporous monolithic ethylbenzene direct dehydrogenation catalyst but also presents a promising avenue for preparing other macroporous monolithic catalysts for diverse transformations.

Super-high N-doping promoted formation of sulfur radicals for continuous catalytic oxidation of H2S over biomass derived activated carbon

N-doped biomass derived activated carbon (NBAC) with superhigh content of surface N atom (17.2 at.%) and microchannel structure was prepared successfully via one-step pyrolysis method using supramolecular melamine cyanurate (MCA) as nitrogen source, and the breakthrough sulfur capacity was very high up to 1872 mg/g for catalytic oxidation of H₂S under room temperature. The superhigh content of N atoms (17.2 at.%) provided massive active sites for the catalytic oxidation of H₂S and formation of sulfur radicals which further helped the dissociation of H₂S and O₂, resulting in continuous catalytic oxidation of H₂S over NBAC after the coverage of nitrogenous sites by multilayer sulfur. Moreover, the microchannel structure with enhanced mesopore volume promoted the mass transfer of reactants and emigration of product elemental sulfur to form multilayer sulfur. This work could provide an insight into the NBAC with superhigh N-doping content for continuous catalytic oxidation of H₂S at room temperature.

Comparison of Graphitic Carbon Nitrides Synthetized from Melamine and Melamine-Cyanurate Complex: Characterization and Photocatalytic Decomposition of Ofloxacin and Ampicillin

Graphitic carbon nitride (g-C₃N₄, hereafter abbreviated as CN) was prepared by the heating of melamine (CN-M) and melamine-cyanurate complex (CN-MCA), respectively, in air at 550 °C for 4 h. The specific surface area (SSA) of CN-M and CN-MCA was 12 m² g⁻¹ and 225 m²g⁻¹ and the content of oxygen was 0.62 wt.% and 1.88 wt.%, respectively. The band gap energy (E_g) of CN-M was 2.64 eV and E_g of CN-MCA was 2.73 eV. The photocatalytic activity of the CN materials was tested by means of the decomposition of antibiotics ofloxacin and ampicillin under LED irradiation of 420 nm. The activity of CN-MCA was higher due to its high SSA, which was determined based on the physisorption of nitrogen. Ofloxacin was decomposed more efficiently than ampicillin in the presence of both photocatalysts.

Nitrogen-doped porous carbon materials: promising catalysts or catalyst supports for heterogeneous hydrogenation and oxidation

Developing novel and efficient catalysts is a critical step in common heterogeneous hydrogenation and oxidation reactions.

Nitrogen-doped carbon nanotubes as efficient catalysts for isobutane dehydrogenation

Large-scale production of isobutene from isobutane requires high-performance and cost-effective catalysts.

Increased active sites and their accessibility of a N-doped carbon nanotube carbocatalyst with remarkably enhanced catalytic performance in direct dehydrogenation of ethylbenzene

This work presents a facile, low-cost, but efficient strategy for synthesizing HN-CNTs with enlarged active sites and their accessibility to reactants for the direct dehydrogenation of ethylbenzene.