For many years the scientific community has believed in a promising future for carbon nanotubes for various applications in such diverse fields as polymer reinforcement, adsorption, catalysis, electronics and medicine. Industrial production of carbon nanotubes and -fibers and the subsequent availability and decrease of price, have rendered this vision feasible. In the last years, several carbon nanomaterial products have been marketed by major chemical companies. In this work, we present an extensive characterization of a representative set of commercially available carbon nanomaterials. Special focus has been put on their quality, i.e. presence of metal or carbonaceous impurities but also homogeneity and structural integrity. The observations are of importance for subsequent use in catalysis where the presence of impurities or defects in the nanostructure can dramatically modify the activity of the catalytic material..

A novel in situ autoreduction route has been developed, by which monodispersed silver nanoparticles with tunable sizes could be easily fabricated on silica-based materials, especially inside the channels of mesoporous silica (MPS). 13C CP/MAS NMR spectroscopy was employed to monitor the whole assembly process. It was demonstrated that the amino groups of APTS (aminopropyltriethoxyl silane)-modified MPS can be used to anchor formaldehyde to form novel reducing species (NHCH2OH), on which Ag(NH3)2NO3 could be in situ reduced. Monodispersed silver nanoparticles were thus obtained. In situ XRD and in situ TEM experiments were used to investigate and compare the thermal stabilities of silver nanoparticles on the external surface of silica gels (unconfined) and those located inside the channels of SBA-15 (confined). It was observed that unconfined silver nanoparticles tended to agglomerate at low temperatures (i.e., lower than 773 K). The aggregation of silver nanoparticles became more serious at 773 K. However, for those confined silver nanoparticles, no coarsening process was observed at 773 K, much higher than its Tammann temperature (i.e., 617 K). Only when the treating temperature was higher than 873 K could the agglomeration of those confined silver nanoparticles happen with time-varying via the Ostwald ripening process. The confinement of mesopores played a key role in improving the thermal stabilities of silver nanoparticles (stable up to 773 K without any observable coarsening), which is essential to the further investigations on their chemical (e.g., catalytic) properties.

In any given matrix control over the final particle size distribution requires a constitutive understanding of the mechanisms and kinetics of the particle evolution. In this contribution we report on the formation mechanism of silver nanoparticles embedded in a soda-lime silicate glass matrix. For the silver ion-exchanged glass it is shown that at temperatures below 410 °C only molecular clusters (diameter <1 nm) are forming which are most likely silver dimers. These clusters grow to nanoparticles (diameter >1 nm) by annealing above this threshold temperature of 410 °C. It is evidenced that the growth and thus the final silver nanoparticle size are determined by matrix-assisted reduction mechanisms. As a consequence, particle growth proceeds after the initial formation of stable clusters by addition of silver monomers which diffuse from the glass matrix. This is in contrast to the widely accepted concept of particle growth in metal-glass systems, in which it is assumed that the nanoparticle formation is predominantly governed by Ostwald ripening processes.

Highly ordered SBA-15 silicas with large cylindrical mesopores (y15 nm) are successfully obtained with the help of NH 4 F by controlling the initial reaction temperatures in the presence of excess amounts of alkanes.With the discovery of M41s, 1 great efforts have been made on the construction of texture controllable mesoporous materials. Among them, tailoring the pore size of the mesoporous materials has been one of the hot issues for the purpose of providing a good performance for specific applications, such as the adsorption/ separation of bulky molecules, the immobilization of enzymes as well as the catalytic transformation reactions of macromolecules, etc. Methods to modify the pore size of the mesoporous materials include the post synthesis treatment, 2 using different surfactant molecules (template) with different chain lengths 3 and employing organic solvents as swelling agents. 4 The addition of swelling agents, such as TMB, alkanes, 5,6 has been proved to be the most effective way in expanding the pore size of MCM-41 silicas (2-10 nm). Recently, the nonionic triblock copolymers templated SBA-15 silicas have attracted great interests due to their larger pores, thicker pore walls and therefore higher hydrothermal stabilities. 7 Meanwhile, the pore size of SBA-15 could be tuned in the range of 7-30 nm by using TMB as expander. However, extensive studies show that a phase transition from highly ordered SBA-15 (7-12 nm) to mesoporous cellular foams (MCF) with large nodded pore structures (y22-42 nm) occurred with increasing amounts of TMB. 8 Therefore, it is still essential to find other methods of tuning the pore size of highly ordered mesoporous materials. In other works, organic auxiliary chemicals (e.g., DMF, 9 alkanes 10,11 ) have also been investigated. Unfortunately, the maximum pore size of the highly ordered SBA-15 is only ca. 12 nm (with decane). Furthermore, when alkanes with shorter chain length (such as nonane, octane, etc.) were employed, disordered MCF silicas were produced under the temporal reaction conditions. 10 Up to now, to our knowledge, the synthesis of highly ordered SBA-15 silicas with cylindrical pore sizes larger than 12 nm has rarely been reported. Herein, it is demonstrated for the first time that the pore size of highly ordered SBA-15 could be continuously expanded to y15 nm by carefully controlling the initial reaction temperatures with excess amounts of alkanes (from nonane to hexane). To our knowledge, it is the largest cylindrical mesopore diameter with regard to highly ordered SBA-15 silicas.As a typical synthesis procedure, 2.4 g of EO 20 PO 70 EO 20 (P123) was dissolved in 84 ml HCl solution (1.30 M), followed by the addition of 0.027 g of NH 4 F. The mixture was then stirred at 288 K to yield a clear solution. Different alkanes (with a constant alkane/P123 molar ratio of y240) and 5.5 ml TEOS were premixed and then introduced into the solution under stirring. The above mixture was stirred at a given temperature for 20 h, and then transferred into an autoclave for furthe...

Hydrodeoxygenation (HDO) is an attractive route for the upgrading of bio-oils produced from lignocellulose. Current catalysts require harsh conditions to effect HDO, decreasing the process efficiency in terms of energy and carbon balance. Herein we report a novel and facile method for synthesizing bimetallic PtCo nanoparticle catalysts (ca. 1.5 nm) highly dispersed in the framework of nitrogen-doped ordered mesoporous carbon (NOMC) for this reaction. We demonstrate that NOMC with either 2D hexagonal (p6m) or 3D cubic (Im3‾ m) structure can be easily synthesized by simply adjusting the polymerization temperature. We also demonstrate that PtCo/NOMC (metal loading: Pt 9.90 wt %; Co 3.31 wt %) is a highly effective catalyst for HDO of phenolic compounds and "real-world" biomass-derived phenolic streams. In the presence of PtCo/NOMC, full deoxygenation of phenolic compounds and a biomass-derived phenolic stream is achieved under conditions of low severity.