Advanced Materials Research Vol. 173

Abstract: Oxidation of gycerol to form various types of important short chain oxygenated derivatives became an important reaction to support biodiesel industries. In this study, a series of AuPd nanoparticles at different metal mole ratios which were 9:1 and 8:2 supported on titania (TiO2) were successfully prepared, characterized and tested for its activity and selectivity in liquid phase oxidation reaction of glycerol. All the catalysts were prepared by deposition-precipitation method with decomposition of urea. AuxPdy/TiO2 catalysts were characterized using XRD, TEM and XPS. The formation of alloy Au-Pd phase was ascertained by XRD and XPS analysis. TEM analyses have shown that the Au and Pd metal particles in the range of 10-30 nm in size were uniformly dispersed on the TiO2 support with narrower size distribution. Higher catalytic activity observed for the catalysts was attributed to the presence of metallic Au0 and PdO phases together with the ‘synergistic’ effect of Au-Pd alloy. The highest selectivity to tartronic acid (55%) was obtained by using Au9Pd1/TiO2 catalyst after 8 h of reaction time at 50oC reaction temperature.

Abstract: The effect of chitosan as a capping agent on the synthesis of ZnS nanoparticles via wet chemical route was studied. The used of chitosan as a capping agent for ZnS nanoparticles had allow the synthesis to be carried out in water which is a more simple and environmental friendly. In dilute acetic acid, the amines in the chitosan will protonated to become NH3+ ions. The positive charges around the ZnS nanoparticles are then used to disperse the nanoparticles via electrostatic repulsion. Chitosan also has an effect on the size of produced nanoparticles. From the X-ray analysis found that the crystallite size of nanoparticles decreases with the increasing of the chitosan concentration. The increase in chitosan concentration will promote the growth of the nanoparticles and subsequently produced smaller nanoparticles.

Abstract: The properties of undoped and La-doped CaCu3Ti4O12 ceramics synthesized via solid state reaction under argon environment had been studied. It was found that La-doped CCTOs gave higher dielectric constant and lower dielectric loss than undoped CCTO. X-ray diffraction (XRD) analysis indicated that all of the sintered samples have single-phase cubic structure (space group ). A minor shifted was observed in the peak positions for La-doped samples, which are attributed to the lattice expansion. The lattice parameter obtained from XRD analysis is 7.348 Å for undoped CCTO and increases to 7.348 – 7.377 Å for La-doped CCTOs. The results proven that La ions have effectively substituted into the Ca site of CCTO.

Abstract: Among all of the one dimensional nanostructures other than titania (TiO2) and carbon, zirconia (ZrO2) have started to gain interest due to its potential in catalytic and energy applications. ZrO2 nanotubes arrays have been prepared using electrochemical anodizing method of Zr foil in fluorine containing glycerol electrolyte. The morphology and structure of the ZrO2 nanotubes are strongly controlled by the applied electrochemical condition especially voltage. Nanotubes with diameter of 30 to 60 nm has been produced by controlling the anodization voltage from 10 to 40 V. The ZrO2 nanotubes formed in this method is partially crystalline even without the heat treatment. The wall thickness is ~10 nm. The self-aligned nanotubes produced by this method could be used for phocatalytic application. The degradation of methylene orange under UV light was successful when ZrO2 nanotubes made in 30 V is used.

Abstract: Gasification of dry palm oil empty fruit bunch (EFB), by using a temperature-programmed instrument was performed to determine the amount of synthesis gas produced. Dry and finely crushed EFB was pre-mixed with calcium oxide. Temperature-programmed gasification (TPG) was done at temperature from 50oC – 550oC and also from 50oC – 700oC using 5% oxygen in He. Both experiments were held for 1hr at the final temperature. The products were monitored using an online mass spectrometer. Major products detected from this reaction were H2, CO, CO2 and CH4. The effect of calcium oxide amount (CaO : EFB ratio) was also investigated. A very significant increase of H2 and CO was observed when nano-sized calcium oxide was used as catalyst compared to bulk one. Reaction at 700oC using nano-sized CaO reduces the production of carbon dioxide during gasification. The characteristics of the catalyst used were analyzed by using XRD and XPS show some significant changes from CaO to CaCO3.

Abstract: A series of titania nanoparticles was successfully synthesized via sol gel method using titanium tetraisopropoxide as a precursor. In this paper, data concerning the effect of pH towards the development of TiO2 nanoparticles is reported. The samples were characterised by x-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). XRD results showed the existence of nanocrystalline anatase phases with crystallite size ranging from 7-14 nm. Surface morphological studies obtain from SEM micrograph showed the particles with rodlike shape are rutile while the spherical shapes are anatase in nature. It was also found the pH of the solution affect the agglomeration of the particles. Results of photocatalytic studies exhibits that titania powder prepared at pH 9 has an excellent photocatalytic activity with degradation 74.7% within 60 minutes.

Abstract: Indialite or α-cordierite was synthesized by glass crystallization method using mainly talc and kaolin and with small amount of MgO, Al2O3, SiO2 to compensate the chemical formulation of non-stoihiometric compositions of cordierite. (3MgO.1.5Al2O3.5SiO2). B2O3, P2O5 and CaO was also added to decrease the melting and sintering temperature of cordierite. The glasses were pelletized and sintered from 850oC up to 1050oC. Phase compositions of both heat treated glass was quantified by X-ray powder diffraction data by the Rietveld method using TOPAS Ver 3 software. Result shows that about 60wt% of α cordierite has successfully crystallized at 850oC. Beside secondary phases (forsterite) which come from initial raw materials, phases from grinding media were also presents in the sample. The contamination was considered high since it has reacted with existence phases to form a new phase at higher temperature. Without any contamination from grinding it was expected to obtain more than 90wt% α cordierite using the same composition.

Abstract: α Cordierite is very important phase in MgO-Al2O3-SiO2 system because of their very outstanding thermal, chemical and electrical properties. In this presents study non-stoichiometry cordierite (MgO:Al2O3:SiO2 = 3:1.5:5) using 2 different initial raw materials ( (i)mixture of pure oxide, and ii) mainly mixture of minerals) were fabricated and compared in terms of phase transformation and physical properties. Cordierite was prepared by glass method at low melting temperature (1350oC). Low melting temperature has resulted in partly crystalline glass which has possesses higher hardness, required longer milling time and result in contamination from grinding media. However, α-cordierite has successfully crystallized and fully densified at 850oC/2h. Activation energy for densification was investigated from thermal expansion coefficient (TCE) results. Other properties that were discussed included thermal properties using DTA/TGA.