Papers by Author: Mohd Ambar Yarmo

Abstract: Recyclability effect on catalytic performance of Ru supported on the mixture of bentonite-TiO₂ for the hydrogenolysis of glycerol was investigated under reaction condition of 150°C, 2.0 MPa hydrogen pressure and 7 h reaction time. Interestingly, the recovered Ru/bentonite-TiO₂ catalyst was found to be active in the repeated runs. The conversion of glycerol increased in the four successive reactions as follows: 61.3%, 65.6%, 68.1% and 75.3%. This suggested that a sort of metal activation affect such as in situ reduction occurred during the repeated reaction. In order to confirm in situ reduction had occurred during the repeated reaction, XPS analysis of used catalyst after each reaction were carried out to study the chemical state of Ru 3d species. Narrow scan of peak Ru 3d revealed that intensity of Ru 3d_5/2 peak at BE 280.0 eV which is corresponding to Ru⁰ species increased until three cycle reaction. This result confirmed that in situ reduction had occurred during the repeated reaction and this made the activities of the catalyst increased upon recycling due to the availability of more metallic Ru on the surface of the catalyst. This study also shows that conversion of glycerol increased linearly with the percentage atomic ratio of Ru metal active site available on the surface of catalyst.

Abstract: Nanocomposite V₂O₅-polyaniline (pani) is produced via micelle solution by using cationic surfactant (cetyltrimethyl ammonium bromide, CTAB) and vanadyl sulfate hydrate as a precursor. TEM results showed that V₂O₅-pani nanocomposite with 20-70 nm in size is formed via micelle solution. This nanocomposite as catalyst is utilized the production of azelaic acid (AA) and pelargonic acid (PA) from oleic acid cleavage in solvent free medium. Various loading percentages of V₂O₅ in Pani are considered and their differences in activity and selectivity are also evaluated. According to GC analysis, results showed that nanocomposite as catalyst is two times more selective to AA compare to bulk V₂O₅ (53%, 28% respectively). Also this nanocomposite indicated higher selectivity to AA and PA rather than nanoV₂O₅ (53% compare to 32%) It is showed that in higher weight percentage of V₂O₅ to polyaniline, the conversion of OA to two main products, AA and PA in ozonolysis reaction ( according to Criegee mechanism ) is higher. Ozone absorption of OA is monitored by FT-IR and the activity and selectivity of catalyst is monitored by GC-FID.

Abstract: Catalysts prepared from a variety of noble metal (Os, Ru, Pd and Au) supported on bentonite using impregnation method were studied and it found these series catalyst system gave different activity and selectivity. Among these catalysts, Os/bentonite and Ru/bentonite catalyst showed high activity in glycerol hydrogenolysis reaction at 150°C, 2.0 MPa initial hydrogen pressure for 7 hours. TEM analysis revealed that these nanometal particles catalyst have different in size and result showed that Os and Ru which have smaller average size in range 1-3 nm gave high activity which are 54.1% and 61.2% respectively. In contrast, less activity was obtained when using Pd/bentonite (29.0%) and Au/bentonite (27.8%) catalyst and TEM result showed that Pd and Au nanoparticles have large average particles size (8-10) nm. NH₃-TPD analysis revealed that Ru/bentonite and Os/bentonite catalyst gave high total acidity and this behaviour contribute to high activity of the catalyst. This study revealed that size of nanoparticles and catalyst acidity play an important role in the activity and selectivity in glycerol hydrogenolysis reaction. These catalysts were also characterized by BET, XRD and XPS in order to get some physicochemical properties of the catalyst.

Abstract: In this research, new chemistry is explored through a simple, efficient and cheap method to synthesize new surfactants from palm oil fatty acids. Oleic acid, which is one of the major fatty acids in palm oil, has been used as a starting material for the synthesis of surfactants. This study focuses on the synthesis and characterization of bolaform surfactants from oleic acid. For this purpose, two steps reaction will be carried out: Firstly, consisted of hydrobromination of oleic acid followed by reaction of 10-bromo-octadecanoic acid with ethane-1,2-dithiol and butane-1,2-dithiol. During the first stage of the reaction, hydrobromination of oleic acid was carried out by adding hydrobromic acid into the oleic acid. The reaction was carried out in benzene as solvent at 30°C and atmospheric pressure. This reaction gives 73% yield of 10-bromo-octadecanoic acid and it yield a black brownish liquid which have the m/z 363.2056 by ESI-MS(ToF) and –CH2-CHBr-CH2-shift (4.02 ppm) was well defined in ¹H-NMR. The separation of 10-bromo-octadecanoic acid was done through thin layer chromatography (TLC) with chloroform and methanol as the eluent and silica plate grade 60 F₂₅₄ as the stationary phase. The second stage of reaction was reacting the 10-bromo-octadecanoic acid with ethane-1,2-dithiol and butane-1,2-dithiol in THF as the solvent and 1,8-Diazabicyclo [5.4.0] undec-7-ene (DBU) as the catalyst respectively. These reactions were carried out at 30°C and atmospheric pressure. Product obtained was a two layers black brownish liquid with white colour precipitate gives m/z: 659.4813 for ethane-1,2-dithiol and m/z:686.5278 for butane-1,4-dithiol respectively using ESI-MS (ToF) mass spectroscopy. Separation was done on both bolaform surfactants through thin layer chromatography (TLC) with hexane and ethyl acetate as eluent and silica plate grade 60 F₂₅₄ as stationary phase, and finally followed by column chromatography. These two new surfactants will be tested for their physical-chemical properties as well as apply on nanomaterial stabilizer.

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 syntheses of estolides via condensation reaction of oleic acid were investigated using heterogenous catalysts. In this study HClO4 is supported onto suitable support to make it environmentally friendly. A series of solid acid catalyst containing 5-45 % of perchloric acid supported onto silica was synthesized and characterized using XRD, BET surface area measurement, TEM and XPS surface analysis. Silica modified with perchloric acid was found to be efficient and environmentally benign solid acid catalyst for estolide synthesis. The reaction was performed at 70 oC for 10 hours to give oleic-oleic monoestolide acid (m/z 563.51 as M-H)-. Based on the experimental findings above, optimum catalytic performance was with 15 % HClO4 loading onto SiO2 to give 98.98 % conversion of the oleic acid with 63.98 % oleic-oleic monoestolide acid selectivity.

Abstract: Various ruthenium precursors (Ru= RuCl3, Ru2 = Ru(acac)3, Ru3 = Ru3(CO)12) supported on bentonite were prepared by conventional impregnation method. Their catalytic performances were evaluated in the hydrogenolysis of glycerol using autoclave Parr reactor under mild reaction conditions of 150°C, hydrogen pressure 30 bar for 7 hours. Among the studied catalyst, 5% Ru/bentonite catalyst prepared from Ru and Ru3 precursor exhibited higher activity which are 79.6% and 72.5% respectively. In contrast, Ru2/bentonite prepared from Ru(acac)3 precusor gave lowest activity (41.8%). In term of selectivity to 1,2-propanediol, Ru2 and Ru3 precusor gave higher selectivity (67.0% and 66.9%) compared to Ru precursor (50.6%). These results indicated that metal precursor plays an important role on activity and selectivity of the catalyst in hydrogenolysis reaction. The catalysts were characterized by XRD, XPS, BET, FESEM-EDX and TEM, and the reasons for the high performances of the catalyst were also discussed.

Abstract: A comparison study on deposition temperature between 40oC and 60oC using new route coating which is inkjet printing technique have been studied in this research paper. The FTO material were prepared by a common mixture technique between precursor solution of SnCl4.5H2O and NH4F as a doping agent. The prepared samples were coated on the glass substrate sized 20mm x 25mm and were calcined at 450oC. The samples were characterized using XRD, XPS, VP-SEM and UV-VIS. From the VP-SEM, the result show the different surface morphology between the two deposition temperatures. Samples prepared at 60oC shows a lot existence some kind of crystal shape on the substrate compared to films deposited at 40oC. Surface studies using XPS technique shows the existence of elements such as Sn, O and F. Detail analysis of these elements shows that Sn 3d5/2 form as Sn-O, O1s as oxygen linkage and F1s as Sn-F. The XPS and XRD results also shows that no significant changes on chemical stoichiometry for both deposition temperatures. The optimum optical properties with lower resistivity were found for thin films deposited at 40oC with 91 %T and 16 Ω/□.

Abstract: Oleic acid which is one of the palm oil derivatives is known to effectively stabilize dispersions of nanomagnetite in nonpolar solvent. Stabilization occurs because the carboxylic acid group covalently reacts with the surface of the magnetite and the aliphatic chain extends out into the nonpolar solvent, preventing aggregation of the particles by a steric (entropic) mechanism. One goal of this work has been to develop a generalized methodology for stabilizing nanomagnetite dispersions using a series of novel surfactants which had been synthesized from palm oil derivatives so that the resultant modified magnetite nanoparticles can be used in a range of applications. The specialty of the surfactants which have thiol compounds attached to the long chain fatty acids have been succesfully coated with magnetite iron oxide as shown on the FTIR spectrum and exhibited a particle size in the range of 25-30 nm as shown on the FT-SEM. These nanoparticles have been characterized by Dynamic Light Scattering, Zeta-potential to examine their stabilities after coating. In addition to that, the X-ray diffraction pattern showed that the modified nanoparticles corresponds to the spinal phase of the bare magnetite iron oxide.

Abstract: Supported ruthenium catalyst on nano-activated carbon (2%Ru/C) and titania (2%Ru/TiO2) were prepared by wet impregnation technique with and without ionic liquid addition (choline chloride with different Lewis acid). Mole ratio of choline chloride and Lewis acid were fixed at 1:3. Catalysts evaluation was performed by glycerol hydrogenolysis reaction at 100°C with initial hydrogen pressure 20 bars for 7 hours reaction. The results showed that supported ruthenium on activated carbon acetylene black with addition of choline chloride/zinc (II) chloride catalyst indicated 30.7% of glycerol converted to 20.6% propylene glycol and 11.4% ethylene glycol. Catalysts profile of XRD showed graphitic phase which could reduce catalyst poisoning effect. XPS analysis showed that Ru/CC-ZnCl2/C catalyst spesies was in Ru4+ state before reaction. In the meantime, mapping analysis using FE-SEM showed well dispersion of ruthenium metal on nano-activated carbon acetylene black with addition of choline chloride/zinc (II) chloride gave the highest selectivity to propanediol. Furthermore, smaller size of nano activated carbon (30-60 nm) than titania (90-120nm) analyzed by TEM may the main course in increasing the conversion of glycerol.