Seong Soo Park

Microwave-accelerated energy-efficient esterification of free fatty acid with a heterogeneous catalyst.

This paper shows energy-efficiency of microwave-accelerated esterification of free fatty acid with a heterogeneous catalyst by net microwave power measurement. In the reaction condition of 5 wt% sulfated zirconia and 1:20 M ratio of oil to methanol at 60°C and atmospheric pressure, more than 90% conversion of the esterification was achieved in 20 min by microwave heating, while it took about 130 min by conventional heating. Electric energy consumption for the microwave heating in this accelerated esterification was only 67% of estimated minimum heat energy demand because of significantly reduced reaction time.

Raney Ni catalysts derived from different alloy precursors Part II. CO and CO2 methanation activity

Catalytic activity, in conjunction with reaction mechanism, was studied in the methanation of CO and CO2 on three Raney Ni catalysts derived from different Ni-Al alloys using different leaching conditions. Main products were CH4 and CO2 in CO methanation, and CH4 and CO in CO2 methanation. Any other hydrocarbon products were not observed. Over all catalysts, CO methanation showed lower selectivity to methane and higher activation energy than CO2 methanation. The catalyst derived from alloy having higher Ni content using more severe leaching conditions, namely higher reaction temperature and longer extraction time, showed higher specific activity and higher selectivity to methane both in CO and CO2 methanation. In CO and CO2 methanation on Raney Ni catalyst, catalytic activity was seen to have close relation with the activity to dissociate CO

Synthesis of TiO2/SiO2 nanoparticles in a water-in-carbon-dioxide microemulsion and their photocatalytic activity

TiO2 and TiO2/SiO2 nanoparticles were prepared by controlled hydrolysis of titanium tetraisopropoxide and tetraethylorhtosilicate in water-in-carbon-dioxide microemulsion using ammonium carboxylate perfluoro-polyether (PFPE-NH4) as a surfactant. These particles were characterized by HRTEM, XRD, FT-IR, TGA and DTA. The particles calcined at 500°C were identified as a nanocrystalline anatase phase, regardless of the titanium tetraisopropoxide/teraethylorthosilicate (TTIP/TEOS) molar ratio. The crystallite size decreased with an increase of the silica content. From FT-IR analysis, the band for Ti-O-Si vibration was observed and the band intensity for Si-O-Si vibration increased with an increase of the silica content. The micrographs of HRTEM showed that the TiO2/SiO2 nanoparticles had a spherical morphology with a narrow size distribution and the lattice fringe was 0.35 nm, which corresponds to the lattice spacing of (101) plane in the anatase phase. In addition, TiO2/SiO2 particles showed higher photocatalytic activity than pure TiO2 and the TiO2/SiO2 (80:20) particles showed the highest activity on the photocatalytic decomposition of p-nitrophenol.

Catalytic combustion of chlorobenzene over V2O5/TiO2 catalysts prepared by the precipitation-deposition method

Catalytic combustion of chlorobenzene over supported vanadium oxides has been investigated. TiO2 was prepared by the sol-gel method from titanium isopropoxide. The supported vanadium oxide catalysts have been prepared by precipitation-deposition and impregnation method and characterized by XRD, FT-Raman and TPR. In the VOx/TiO2catalysts prepared using the impregnation method, when vanadium loading reaches 3 wt.%, the activity shows a maximum. However, in the VOx/TiO2catalysts prepared by precipitation-deposition, when vanadium loading reaches 7 wt.%, the activity shows a maximum. This result suggests that the precipitation-deposition can yield a higher metal loading on the support and a high dispersion compared to the impregnation method.

Raney Ni catalysts derived from different alloy precursors (I) morphology and characterization

Ni-Al alloys containing 41.3, 49.2 and 59.9 wt% Ni were leached by reaction with 20 wt% aqueous NaOH solution under different temperature and time. The reactivities of alloys and morphologies of resultant catalysts were investigated. A large difference in reactivities of alloys toward alkali solution was revealed according to the composition of the alloy. As Al content in precursor alloy increased, the reactivity of alloy toward alkali solution increased. It was shown that, during leaching, reaction in Ni 41.3 wt% alloy is restricted to reaction interface, whereas that in Ni 49.9 wt% alloy occurs throughout the product layer. Surface area and pore size distribution were seen to be strongly dependent upon leaching conditions and relatively independent of the composition of precursor alloy.

Preparation of nanosized TiO2 particles via ultrasonic irradiation and their photocatalytic activity on the decomposition of 4-nitrophenol

TiO2 nanoparticles were prepared by hydrolysis of TTIP (titanium tetraisopropoxide) using an ultrasonication technique coupled with a sol-gel method. The physical properties of nanosized TiO2 were investigated. The photocatalytic degradation of 4-nitrophenol was studied by using a batch reactor in the presence of UV light. The crystallite size of the anatase phase is increased with an increase of REtOH ratio (EtOH/H2O molar ratio). The particles’ crystallite size prepared with and without ultrasonic irradiation is marginally different. Those particles prepared with ultrasonic irradiation show a higher activity on the photocatalytic decomposition of 4-nitrophenol compared to those prepared without ultrasonic irradiation. The photocatalytic activity decreases with an increase of REtOH ratio. In addition, the photocatalytic activity shows the highest value on the titania particle calcined at 500 ‡C.

Study of surface properties of blend films using stereocomplexation between enantiomeric polylactide chains

This study investigated the stereocomplex-induced surface structure of enantiomeric poly(lactide) (PLA) blend films by differential scanning calorimeter, electron spectrometer for chemical analysis, and contact angle measurements. The design of the blend systems is based on principles of surface segregation of a modified component with a low surface energy, fluorocarbons (F), as an end group. The two blend systems, uncomplexed (F-l-PLA/l-PLA) and complexed (F-l-PLA/d-PLA), showed quite different surface structures: the surface segregation of fluorocarbon groups in the (F-l-PLA/l-PLA) blend film was observed while the surface structure of the (F-l-PLA/d-PLA) blend film was similar to its bulk one. This indicates that the interchain interaction to form stereocomplexes between l- and d-PLA is strong enough to overcome the driving force of fluorocarbon groups toward the surface.

A Study for Microwave Enhanced Synthesis of NIR Absorbing Materials

Symmetrically and unsymmerically substituted bis-dithiobenzil nickel complexes containing four substituted and unsubstituted methoxy groups were synthesized from a benzoin compound using phosphorous pentasulfide under the conventional thermal and microwave processing. The efficiency of microwave synthesis over the conventional thermal synthesis was illustrated by the yield of bisdithiobenzil nickel complex dyes. The samples were characterized by the means of elemental analyzer, 1HNMR, IR spectroscopy, Uv-vis spectroscopy and DSC.

Preparation of Organic/Inorganic Nanocomposites with Microwave Process

Polymer/layered silicate nanocomposities were prepared by in situ polymerization with microwave process. The influence of the amount of clay on the structure and thermal properties for the synthesized nanocomposites were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). It was found that the structure of nanocomposites, an intercalated/exfoliated structure, depended on the clay content.

Comparative study of photo- and thermal catalytic hydroxylation of phenol with H2O2OVER TS-1

The hydroxylation of phenol into catechol (CAT) and hydroquinone (HQ) with hydrogen peroxide and TS-1 catalyst was carried out via both photo- and dark (thermal) reactions. The conversion of phenol and the product ratio of CAT/HQ in the photocatalytic reaction were higher than those in dark (thermal) reaction.