Polysulfone ultrafiltration membranes impregnated with silver nanoparticles show improved biofouling resistance and virus removal.

Carbon nanotubes are promising materials for various applications. In recent years, progress in manufacturing and functionalizing carbon nanotubes has been made to achieve the control of bulk and surface properties including the wettability, acid–base properties, adsorption, electric conductivity and capacitance. In order to gain the optimal benefit of carbon nanotubes, comprehensive understanding on manufacturing and functionalizing carbon nanotubes ought to be systematically developed. This review summarizes methodologies of manufacturing carbon nanotubes via arc discharge, laser ablation and chemical vapor deposition and functionalizing carbon nanotubes through surface oxidation and activation, doping of heteroatoms, halogenation, sulfonation, grafting, polymer coating, noncovalent functionalization and nanoparticle attachment. The characterization techniques detecting the bulk nature and surface properties as well as the effects of various functionalization approaches on modifying the surface properties for specific applications in catalysis including heterogeneous catalysis, photocatalysis, photoelectrocatalysis and electrocatalysis are highlighted.

Carbon nanotube catalysts: recent advances in synthesis, characterization and applications.

Multi-walled carbon nanotubes (MWNT) and TiO2 composite catalysts were prepared by a modified sol–gel method. The nanoscaled composite materials were extensively characterized by TG, N2 adsorption-desorption isotherm, XRD, SEM, EDX, TEM and UV–vis spectra. The photocatalytic degradation of phenol was performed under visible light irradiation on these catalysts. An optimum of synergetic effect on photocatalytic activity was observed for a weight ratio MWNT/TiO2 equal to 20% with an increase in the first-order rate constant by a factor of 4.1. The synergetic effect, induced by a strong interphase interaction between MWNT and TiO2, was discussed in terms of different roles played by MWNT in the composite catalysts.

Visible light photodegradation of phenol on MWNT-TiO2 composite catalysts prepared by a modified sol–gel method

Tandem Reaction Sequences under Hydroformylation Conditions: New Synthetic Applications of Transition Metal Catalysis.

This review article explores three major aspects of the wet oxidation (WO) and catalytic wet oxidation (CWO) processes (with the major focus being on WO and CWO, using air or oxygen as an oxidant). These aspects are (a) the fundamental chemistry of WO/CWO; (b) important aspects of catalysts, with regard to the CWO process; and (c) engineering aspects of the WO/CWO process. The applications of WO and CWO technology to treat industrial wastewater clearly illustrate the potential of these processes for treating wastewater from a wide number of industries. WO/CWO is a fertile area of research with significant scope for further research and innovation, particularly in the areas of catalyst development, the understanding of catalytic mechanisms, and the fundamental chemistry that occurs during WO/CWO. Selected examples of findings to date are discussed in this review.

Wet Oxidation and Catalytic Wet Oxidation

A chemical vapour deposition process for the production of carbon nanospheres

Carbon nanotubes produced by fluidized bed catalytic CVD: first approach of the process

Multi-walled carbon nanotubes (MWCNTs) have been produced with high selectivity by fluidized bed catalytic Chemical Vapor Deposition from ethylene on Fe/Al2O3 catalysts. The influence of operating parameters such as deposition duration, temperature, ethylene and hydrogen partial pressures and iron loading, on MWCNT productivity, process selectivity, characteristics of final powders and chemical composition of the outlet gases has been analyzed. Using gas phase chromatography, methane and ethane have been detected whatever the conditions used. Between 650 and 750°C, no catalyst deactivation occurs because nucleation remains active all along the synthesis thanks to the explosion of the catalyst grains. Above 650°C, ethane itself produces MWCNTs, whereas methane does not react in the temperature range 550-750°C. The formation of MWCNTs induces marked bed expansions and sharp decreases of grain density. Apparent kinetic laws have been deduced from the collected data. The apparent partial orders of reaction for ethylene, hydrogen and iron were found to be 0.75, 0 and 0.28 respectively.

Kinetic study of carbon nanotubes synthesis by fluidized bed chemical vapor deposition

Carbon-supported iridium catalysts were prepared by different incipient wetness impregnation methods and by organometallic chemical vapor deposition. The catalysts were characterized by N2 adsorption, TPD, SEM and H2 chemisorption measurements. The results obtained indicate a clear dependency of the metal-phase dispersion on the pre-treatment of the carbon support and the impregnation method. Their activity for catalytic wet air oxidation of butyric and iso-butyric acid aqueous solutions was investigated in a stirred reactor at 473 K and 0.69 MPa of oxygen partial pressure. The conversions obtained after 2 h were 43 and 52%, with respect to each carboxylic acid, when the most active catalysts were used. The measured conversions and initial reaction rates correlate well with the exposed metal area. A rate equation was determined from measurements of the initial reaction rates at different oxygen partial pressures, temperatures and catalyst mass loads. The results were modeled considering a heterogeneously catalyzed free-radical mechanism.

Ph. Kalck

Papers

A chemical vapour deposition process for the production of carbon nanospheres

Carbon nanotubes produced by fluidized bed catalytic CVD: first approach of the process

Kinetic study of carbon nanotubes synthesis by fluidized bed chemical vapor deposition

Carbon-supported iridium catalysts in the catalytic wet air oxidation of carboxylic acids: kinetics and mechanistic interpretation

Direct synthesis of acetals by rhodium catalysed hydroformylation of alkenes in the presence of orthoformate