Fengwen Yan

Steam reforming of glycerol over Pt-MCM-41 synthesized in a one-step process

Pt-MCM-41 materials were synthesized by a simple method via simultaneous self-assembling and Pt incorporation using cetyltrimethylammonium chloride (CTAC) as a structure directing agent. Structural characterization of the sample was carried out by N2 sorption, XRD and TEM measurements. The highly ordered structure of MCM-41 was not appreciably affected by the formation of the Pt particles. Unlike related results, the Pt nanoparticles were incorporated into the mesopores and embedded into the pore walls as framework. The Pt-MCM-41 sample was tested as a catalyst in the steam reforming of glycerol in which it exhibited moderate activity, high selectivity to hydrogen, and very low selectivity to light alkanes.

Synthesis and characterization of spherical porous calcium carbonate with ordered secondary structures in the presence of polymer with double hydrophilic ionic moieties

Sulfonated poly(aspartic acid) (SPASP) of narrow polydispersity was successfully employed in the facile synthesis of porous calcium carbonate microspheres with regular trigonal star-like secondary structure units and significantly improved surface area (56.3 m2 g−1). Based on the CaCO3 particles morphology through different aging times, a mechanism for the formation of porous CaCO3 microspheres with trigonal star-like secondary structures in the presence of SPASP was proposed.

A fluorescent carbon nitride nanofibrous hydrogel for selective sensing of Cu2

A carbon nitride nanofibrous hydrogel was fabricated by self-assembly/gelation of carbon nitride aqueous solution derived from thermal evaporation of bulk graphitic carbon nitride. The structure, chemical composition and optical properties of the as-prepared nanofibers were well investigated. The π–π interactions between nitrogen containing aromatic rings and hydrogen bonds between hydroxyl and amino groups were the driving forces for the formation of nanofibers and the hydrogel. A fluorescent nanofiber suspension can be obtained by dilution of the hydrogel with water. Due to the excellent fluorescence properties and the high dispersion stability in water, the carbon nitride nanofibers can be employed as a fluorescent probe for the selective sensing of Cu2+.

Hydrogen peroxide as a crystal growth modifier of CaCO3

Using exclusively H2O2 as an additive, facile morphology control over CaCO3 crystal aggregation was realized readily by changing the concentrations of H2O2 and the pH values of the crystallization system. The ionization of H2O2 to [H–O–O]− and [O–O]2− and the generated gas molecules played significant roles in modifying the crystal morphologies. Based on the CaCO3 particles morphology through different aging times, a mechanism about the formation of CaCO3 crystals in the presence of H2O2 was proposed.

Vinyl acetate formation in the reaction of acetylene with acetic acid catalyzed by zinc acetate supported on porous carbon spheres

A kind of porous carbon spheres (PCS) was prepared by the carbonization of poly(vinylidene chloride) synthesized by suspension polymerization. Structure analyses revealed the existence of bumps and holes on the surface of PCS. The PCS, with the pore size between 0.8–1.2 nm, could be used as the support of zinc acetate because of the regular shape, high specific surface area, and good mechanical strength. Vinyl acetate was produced from acetylene and acetic acid using the PCS-supported zinc acetate (PCS-Zn) under mild conditions. In a single-pass operation performed at 220°C, the conversions of acetic acid and acetylene reached 22.6 and 5.3% respectively while the activity of vinyl acetate formation was above 1000 g mol−1 h−1.

Hydrogen peroxide triggered morphological evolution of barium sulfate crystals under basic conditions

Inorganic small molecule H2O2 was utilized as an additive to control the crystallization of BaSO4. The evolution from simple flake-like to pillow morphologies shaped with dominant (hk0) planes and (001) plane was observed by just increasing the pH value and the H2O2 concentration in the reaction solution. Accompanying the change, the hexagonal (001) plane becomes the main face with the side faces transforming into the (210) and (100) faces. The inhibition on the [001] direction results in the appearance of a (001) face and the faster growth in the [010] direction influences the shape of the (001) plane to be hexagonal, elongated along the [010] direction. The crystalline morphologies of urchin-like BaSO4 at different mineralization times were investigated by SEM and a four-step evolution mechanism was proposed. Selective adsorption of HO2− originated from the decomposition of H2O2 over the BaSO4 particles, following gradual O2 evolution, and the formation of BaO2 were considered to be the key factors in the structural evolution. The structural units of urchin-like BaSO4 were strips with hexagonal basal faces, which could be seen as defect-free one-dimensional single crystals. The continuous variation of the morphology captured in this work may provide a deeper understanding of the formation mechanism of one-dimensional barium sulfate fibers. In addition, the results indicate that H2O2 may act as an additive for the crystallization of minerals. Because the final decomposition products are H2O and O2, H2O2 is especially suitable for directing the crystallization demanding high purity of the products.

Facile fabrication of hierarchical ZnO nanowire aggregates using rose-like peroxide precursor as the inorganic template

The complex rose-like inorganic templates assembled by the ZnO/ZnO2 hybrid nanosheets have been constructed with hydrogen peroxide as an additive to control the structure of a precursor. The surface morphologies of the inorganic templates can be controlled by varying the reaction time and the amount of hydrogen peroxide. The process of the precursor growth takes a dissolution-growth route under hydrothermal conditions. The chemical composition of the precursor is determined by X-ray diffraction (XRD) and Raman analyses, indicating the existence of peroxide in the precursor. Combined with transmission electron microscopy (TEM) data, the ZnO/ZnO2 hybrid precursor is proposed to act as an inorganic template for the growth of secondary crystal structures. The dandelion-like ZnO crystal is fabricated by using rose-like peroxide precursor as the inorganic template. The structural evolution of hierarchical ZnO crystal is studied by monitoring the influence of the reaction time.

Supported Ag nanoparticles as trace iodide adsorbent from acetic acid

Ag nanoparticles (AgNPs) were used as adsorbent to remove trace iodide from acetic acid. Under identical conditions, AgNPs adsorbent with 0.5 wt % Ag has the same performance as commercial adsorbent with 10 wt % Ag+. In addition, Ag loss of AgNPs adsorbent is remarkably lower than that of commercial adsorbent. The Ag content in AgNPs adsorbent affects its adsorption performance, and the optimal content is 1.0 wt %. Saturated AgNPs adsorbent can be regenerated by hydrogen reduction and reused with satisfying performance. The properties of AgNPs adsorbent are based on surface effect of nanoparticles, differing from commercial Ag+ type adsorbents. In a word, AgNPs adsorbent is of high efficiency, low Ag loss and easy recycling, thus making it “green adsorbent” for removing iodide from acetic acid.