Volume 29, Issue 6

This review discusses a fundamental kinetic approach for the modeling of the conversion of complex hydrocarbon mixtures, called single-event approach. Based upon the transition state theory and statistical thermodynamics and combined with the linear free energy relationship of Evans and Polanyi, it significantly reduces the number of independent kinetic parameters. It is applied to the hydrocracking of vacuum gas oil and the methanol-to-olefin process, which is subject to rapid catalyst deactivation by coke formation. The approach considers a detailed composition of the complex feedstocks, made possible by modern analytical techniques and also by recently introduced computerized methods for the molecular reconstruction of oil fractions. The very large reaction networks should be generated by computer and this aspect is also reviewed. Finally, the application of the method of structural contributions in the reduction of the number of independent kinetic parameters of the hydrodesulfurization of oil fractions is also dealt with.

Due to recent progress in synthetics, the ready obtainment of various N-substituted carbazole heterocycles opened a wide window of scientific and industrial opportunities in different R&D domains. As summarized in this review article, such attractive R&D domains concern (a) electrochemically grown functional polycarbazole films for (bio/chemo)sensing, covalent grafting of biomolecules, nanomaterial fabrication (polycarbazole-containing nanorings and dendrimers), and surface patterning/engineering (biochip fabrication), and (b) oxidatively grown materials containing a polycarbazole phase (template or non-templated liquid oxidation polymerizations). This last general approach led to numerous developments in the fabrication of various composite materials incorporating single/multiwalled carbon nanotubes, graphene oxide, and magnetic magnetite-based nanoparticles for the ultrasensitive detection of DNA hybridization for example. Some liquid-phase oxidative polymerizations of UV-sensitive carbazole-containing species also afforded corresponding polymeric UV-reactive microspheres for UV surface patterning and functionalization/structuration. All these novel polycarbazole-containing species generally possess interesting optical properties useful for sensing and photoelectronic/photovoltaic applications. In summary, the already proven rich organic chemistry and corresponding (electro/chemical) polymerization properties of such specific carbazole heterocycles are expected to generate even more wider output applications far beyond current knowledge in the field (combinatorial polymeric engineering, biocompatible medical devices/materials, for example).

Various polymers such as nylon, polypropylene, polystyrene, ethylene vinyl acetate, epoxy resins, polyurethanes, polyimides, and polyethylene terephthalate can be reinforced by adding nanofillers with dimensions <100 nm. Fillers can be in the form of particles (minerals), sheets (exfoliated clay stacks), or fibers (carbon nanotubes or electrospun fibers). Polypropylene and clay are most widely used components for making nanocomposites. For proper dispersion of clay with polypropylene, maleic anhydride polypropylene is commonly used. The composites thus prepared have applications in food packaging, structural, chemical, electrical/electronic, and medical fields.

Natural gas, refinery gas, and coal gas contain acid gases such as hydrogen sulfide (H 2 S) and carbon dioxide that must be removed from the gas stream due to the toxicity of H 2 S and to prevent corrosion to piping and production facility caused by the acid gases. In this article, current technologies for the acid gas removal are selected and reviewed. The review includes absorption, adsorption, conversion of H 2 S into elemental sulfur, and membrane reactor for H 2 S decomposition and desulfurization. Recently, hollow fiber membrane contactor has been in the limelight of research in H 2 S absorption from gaseous mixture due to its potential to overcome problems such as foaming and loading. Recent trends on Claus tail gas cleanup technologies are highlighted due to the recent progress in membrane technology. The article also suggests current research on the acid gas removal technology using catalytic membrane reactor. The interest on finding suitable active component and support and studying the membrane structure for enhanced removal of acid gases is likely to be rekindled in the near future.

Polyphenylene sulfide (PPS) is a versatile material that gives extruded and molded components the ability to meet exceptionally demanding criteria. This semicrystalline engineering thermoplastic has outstanding thermal stability, superior toughness, inherent flame resistance, and excellent chemical resistance. It also has high mechanical strength, impact resistance, and dimensional stability as well as good electrical properties. The present review outlines the synthesis methods, characterizations, and electrical and dielectric properties of PPS composite. Its structural and morphological characteristics, studied for advanced applications such as photovoltaic cells, gas sensors, and supercapacitors, are in prospect. In the composite phase, the electric and dielectric properties of PPS are found to be improved.