A series of polypyrrole supported WO3were fabricated and characterized by FT-IR, XRD, XPS, BET, TGA, and FESEM-EDX. The activity of the catalysts was tested in glycerol esterification with acetic acid, and it found that WO3-Ppy-20 (nanocomposite with 20% WO3loaded) showed the maximum catalyst activity with 98% and selectivity of 70% to triacetin at 110°C with a reaction duration of 10 h and also recorded the highest selectivity (75%) for acetylation of glycerol to monoacetin with about 59% conversion only. The highest acidity of WO3-Ppy-20 is also confirmed using TPD-NH3analysis. The activity and selectivity to triacetin of the catalyst were enhanced by increasing WO3loading amount, resulting in 82% conversion for WO3-Ppy-5 with about 32 and 50% selectivity to monoacetin and diacetin and about 18% selectivity to triacetin; in case of WO3-Ppy-20, these amounts were changed to 5, 25, and 70% selectivity to monoacetin, diacetin, and triacetin, respectively with the conversion of 98%. TPD-NH3analysis found that polypyrrole supported WO3increases the catalyst acidity of WO3. BET and FESEM analyses revealed that WO3particles were well dispersed with the smallest average size in nanocomposite compared to pure WO3, which could contribute to the high activity of WO3-Ppy catalyst for esterification of glycerol.

SUMMARY Polyaniline (Pani), vanadium oxide (V2O5), and Pani/V2O5 nanocomposite were fabricated and applied as a cathode catalyst in Microbial Fuel Cell (MFC) as an alternative to Pt (Platinum), which is a commonly used expensive cathode catalyst. The cathode catalysts were characterized using Cyclic Voltammetry and Linear Sweep Voltammetry to determine their oxygen reduction activity; furthermore, their structures were observed by X‐ray Diffraction, X‐ray Photoelectron Spectroscopy, Brunauer–Emmett–Teller, and Field‐Emission Scanning Electron Microscopy. The results showed that Pani/V2O5 produced a power density of 79.26 mW/m2, which is higher than V2O5 by 65.31 mW/m2 and Pani by 42.4 mW/m2. Furthermore, the Coulombic Efficiency of the system using Pani/V2O5 (16%) was higher than V2O5 and Pani by 9.2 and 5.5%, respectively. Pani–V2O5 also produced approximately 10% more power than Pt, the best and most common cathode catalyst. It declares that Pani–V2O5 can be a suitable alternative for application in a MFC system. Copyright © 2013 John Wiley & Sons, Ltd.

Sulphate- and phosphate-loaded silicas were synthesised using the sol-gel method with different sulphate and phosphate loadings. These catalysts were characterised using Fourier transform infrared spectroscopy (FT-IR), the Brunauer-Emmett-Teller (BET) method and X-ray photoelectron spectroscopy (XPS). Acidity was measured using the temperature-programmed desorption of ammonia (TPD-NH3) method. The results showed that glycerol esterification with acetic acid conversion decreased as follows: α(H2SO4) (100 %) > α(H3PO4) (99 %) > α(silica loaded with 20 % sulphuric acid) (SS-20; 98 %) > α(silica loaded with 20 % phosphoric acid) (PS-20; 83 %). These studies suggest that the solid acid catalytic activity in the esterification of glycerol is highly dependent on catalyst acidity strength, pore size and surface area.

Glycerol monooleate (GMO) as an esterification product of oleic acid and glycerol is highly potential as an anti-friction substance in the engine lubricant. The purpose of this work is to study the synthesis, characterization and catalytic performance of solid heteropoly acid catalysts, namely silicotungstic acid bulk (STAB) and STA-silica sol gel (STA-SG). The activity and selectivity of STAB and STA-SG in the esterification reaction have been investigated and compared to the homogeneous catalyst i.e. sulphuric acid (H2SO4). The synthesized catalysts were characterized by BET, XRD, TEM, XPS and TPD-NH3. BET analyses shown that the STA-SG catalyst is very high in surface area compared to STAB of 460.11 m2/g and 0.98 m2/g, respectively. From the XPS analyses, there was a significant formation of W-O-Si, W-O-W and Si-O-Si bonding in STA-SG compared to that in STAB. The main species of O1s (90.74 %, 531.5 eV) followed by other O1s peak (9.26 %, 532.8 eV) were due to the presence of W-O-W and W-O-Si bonds, respectively. In addition, the ease of separation for STA-SG catalyst was attributed to its insoluble state in the product phase. The esterification products were then analysed by FTIR and HPLC. Both the H2SO4 and the STAB gave high conversion of 100% and 98%, while lower selectivity of GME with 81.6% and 89.9%, respectively. On the contrary, the STA-SG enabled a conversion of 94%, while significantly higher GME selectivity of 95% rendering it the more efficient solid acid catalyst.

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