Copyright (c) 2012 All rights reserved. http://works.bepress.com/hadi_nur Recent documents in Hadi Nur en-us Wed, 08 Feb 2012 04:03:38 PST 3600 http://works.bepress.com/hadi_nur/64 http://works.bepress.com/hadi_nur/64 Sun, 22 Jan 2012 18:32:24 PST Titanium-amine functionalized silica was successfully prepared by a so-called one-pot approach by using 3-aminopropyltrimethoxysilane (APTMS), tetraethoxysilane (TEOS) and titanium(IV) sulfate as precursors. It is demonstrated that the TEOS/APTMS molar ratio in the synthesis of titaniumamine functionalized silica affected the local coordination of titanium and its corresponding positive impact on catalytic activity in oxidation of limonene by aqueous hydrogen peroxide.

]]> Lai Sin Yuan et al. Heterogeneous catalysis http://works.bepress.com/hadi_nur/63 http://works.bepress.com/hadi_nur/63 Sun, 22 Jan 2012 18:28:43 PST Acid treatment using H2SO4, HCl and H3PO4 has been carried out in an attempt to improve catalytic performance of silica-titania aerogel. X-ray diffraction results showed the amorphous structure of the aerogels remained after the acid impregnation and calcinations steps. Hammert analysis revealed these acid modified silica-titania aerogels were superacids with pKa < -14.52. Different Ti species was observed in the samples upon the acid treatment. As compared to silica-titania aerogel, Lewis acidity increased remarkably in HCl treated sample without formation of any Brønsted acid site. Meanwhile, H2SO4 and H3PO4 treated samples possessed both Lewis and Brønsted acid sites. The catalytic performance of these samples was evaluated through a consecutive transformation of 1-octene to 1,2-octanediol through the formation of 1,2-epoxyoctane using aqueous hydrogen peroxide as oxidant.

]]> Siew Ling Lee et al. Heterogeneous catalysis http://works.bepress.com/hadi_nur/62 http://works.bepress.com/hadi_nur/62 Sun, 22 Jan 2012 18:24:26 PST Studies on the chemically stabilized soils have shown that the effectiveness of treatment is largely dependent on soil’s natural environment. In tropical kaolin soils, phosphoric acid may be used as an alternative to traditional alkaline stabilizers for improving soil properties. This research was carried out in an effort to identify the timedependent soil-stabilizer reactions. Data for the study of characterization of treated samples were obtained from X-ray diffractometry, energy dispersive X-ray spectrometry, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and leaching analysis. Based on the collected data, the kaolinite mineral with pH-dependent structural properties showed slightly different behavior both in basic and in acidic mediums. Also, it was found that the chemical stabilizers preferentially attacked the alumina surface of the clay particles. Therefore, it was rational to suggest that with respect to lime and phosphoric acid treatment, aluminate hydrate compounds are more likely to be formed.

]]> Khairul Anuar Kassim et al. Geotechnical engineering http://works.bepress.com/hadi_nur/61 http://works.bepress.com/hadi_nur/61 Sun, 22 Jan 2012 18:10:23 PST The purpose of this lecture is to introduce several designs of heterogeneous catalytic systems. The aim is to assist researchers in the field of catalytic chemistry in gaining an understanding of the catalytic phenomena through the design and physicochemical properties of the catalysts. This is an inaugural professorial lecture which will be useful for several purposes. The cohesive aspect of certain advances is shown by bringing together researches published in different journals, including, in a few cases, journals of limited circulation. This should aid historical studies of heterogeneous catalysis researches at Universiti Teknologi Malaysia (UTM). It will give the reader a feeling of the general nature of research. This lecture was compiled based on classification from the catalytic processes that comprised of examples from researches that were carried out by the author together with his colleagues and students from 1996 to 2011 at UTM. Another message to be conveyed in this lecture is that scientific research is enjoyable. Hopefully, this lecture can give an inspiration on how the design of the catalyst can be related to the physicochemical properties and the catalytic action for the chemical reactions, and may assist in the further search for novel approaches to heterogeneous catalysis. Developing programmable systems and self-organizational approaches in heterogeneous catalysis are among of the most challenging design tasks for current heterogeneous catalysis.

]]> Hadi Nur Heterogeneous catalysis http://works.bepress.com/hadi_nur/60 http://works.bepress.com/hadi_nur/60 Sun, 22 Jan 2012 18:05:53 PST Porous Polystyrene nanospheres (PSNs)-Cd metal thin film of about 375.72 angstrom (Ǻ) on hydrophilic silicon wafer has been successfully fabricated from its liquid colloidal prepared by 40 KHz ultrasound for 45 minute at room temperature. This porous fabrication was aiming to confirm the proposed structure of PSNs based-porous thin film models depicted in Fig.1. Surface morphology of the porous thin film explored with a field emission scanning electron microscopy (FESEM) showed that Cd metals atomic particles might be deposited on the PSNs particles surface so that they could enhance the porosity of the thin film material. Absorption capability of the porous thin film assayed using both ultraviolet-visible (UV-Vis) and infrared (IR) light proved that Cd metals atomic particles were a main part of the porous thin film which could enhance significantly the absorption performance. It could be concluded that both kind of nano- sunken and nano-wells unique binding sites might have been generated inside the pores during fabricating them.

]]> Pratama Jujur Wibawa et al. Heterogeneous catalysis http://works.bepress.com/hadi_nur/59 http://works.bepress.com/hadi_nur/59 Sun, 22 Jan 2012 17:56:09 PST Heterogeneous asymmetric catalysis remains as an exciting research field in chiral catalysis since the heterogeneous catalyst can be separated easily from the reaction mixture compare to conventional homogeneous catalyst. The aim of the research is to develop and investigate a novel heterogeneous asymmetric catalyst using amino acid as chiral promoter. The catalysts were synthesized by attachment of amino acids such as L-glutamic acid, L-leucine and L-phenylalanine onto the hydrophilic part of hydrolyzed octadecyltrichlorosilane (OTS). The short-range order structure of silicon and organic groups in the catalysts has been confirmed by solid-state 29Si and 13C cross-polarization magic-angle-spinning (MAS) NMR spectroscopies, respectively. The solid state MAS NMR results showed that the amino acids interacted with hydrolyzed OTS. This phenomenon was supported by 13C NMR spectra which showed the signals of the peaks of L-glutamic acid, L-leucine and Lphenylalanine were shifted towards a higher magnetic field. It was confirmed by 29Si NMR spectra which showed the peaks of cross-linked –(OH)Si(R)-O-(OH)Si(R)- (R=octadecyl group) whereas those of R–Si≡(OSiR)3 were not present in amino acid-hydrolyzed OTS. This result suggested that the amino acid was attached via cross-linked –(OH)Si(R)-O-(OH)Si(R)- of hydrolyzed OTS. The amino acidhydrolyzed OTS materials were used as catalysts for the asymmetric hydration of epoxycyclohexene to yield two diastereoisomers, namely (1R,2R)-trans-1,2-cyclohexanediol, (1S,2S)-trans-1,2-cyclohexanediol and cis-1,2-cyclohexanediol.

]]> Hadi Nur et al. Heterogeneous catalysis http://works.bepress.com/hadi_nur/58 http://works.bepress.com/hadi_nur/58 Sun, 22 Jan 2012 17:37:15 PST In this research, the time-dependent changes induced in charge characteristics of phosphoric acid and lime treated quartz-rich kaolinitic soil were investigated. Also, in order to study the relationship between the exchange capacity and the pore water chemistry, pH measurements was performed on cured samples. Based on the collected data, it was found that the pH of stabilized soils showed a tendency for reaching soil’s natural pH with increasing curing time. In addition, the increase in number of broken bonds around the edges of soil particles and also the formation of cementitious compounds that acquired negative charges contributed to achieving higher CECp values at longer curing periods. From engineering point of view, the lime treated samples revealed the highest degree of improvement with an approximately 16-fold strength increase in comparison to the natural soil over an 8 months curing period.

]]> Amin Eisazadeh et al. Geotechnical engineering http://works.bepress.com/hadi_nur/57 http://works.bepress.com/hadi_nur/57 Sun, 22 Jan 2012 17:22:25 PST Electric-field-induced oxidation of benzhydrol to benzophenone over conducting surface containing titanium dioxide has been carried out by using hydrogen peroxide as oxidant. The results suggest the occurrence of synergistic effect of electric field and titania in which the interphase area between the titania particles and conducting surface is the most active region for the reaction. The electrical field on the generation of surface charge to induce the adsorption of organic substrate has also been confirmed by dye adsorption experiments.

]]> Amelia Boon Hoo et al. Heterogeneous catalysis http://works.bepress.com/hadi_nur/56 http://works.bepress.com/hadi_nur/56 Sun, 22 Jan 2012 17:19:46 PST Acid treatment using H2SO4, HCl and H3PO4 has been carried out in an attempt to improve catalytic performance of silica-titania aerogel. X-ray diffraction results showed the amorphous structure of the aerogels remained after the acid impregnation and calcinations steps. Hammert analysis revealed these acid modified silica-titania aerogels were superacids with pKa < -14.52. Different Ti species was observed in the samples upon the acid treatment. As compared to silica-titania aerogel, Lewis acidity increased remarkably in HCl treated sample without formation of any Brønsted acid site. Meanwhile, H2SO4 and H3PO4 treated samples possessed both Lewis and Brønsted acid sites. The catalytic performance of these samples was evaluated through a consecutive transformation of 1-octene to 1,2-octanediol through the formation of 1,2-epoxyoctane using aqueous hydrogen peroxide as oxidant.

]]> Siew Ling Lee et al. Heterogeneous catalysis http://works.bepress.com/hadi_nur/55 http://works.bepress.com/hadi_nur/55 Thu, 20 Jan 2011 23:10:04 PST The role of Lewis and Brönsted acidities in alkylation of resorcinol is demonstrated through the gallium-zeolite beta by varying the amount of Lewis and Brönsted acid sites. The synergism of Lewis and Brönsted acid sites take place heterogeneously in Friedel-Crafts alkylation of resorcinol with methyl tert-butyl ether to produce 4-tert-butyl resorcinol and 4,6-di-tert-butyl resorcinol as the major and minor products, respectively.

]]> Hadi Nur et al. Heterogeneous catalysis http://works.bepress.com/hadi_nur/54 http://works.bepress.com/hadi_nur/54 Sat, 23 Oct 2010 09:37:14 PDT The effect of calcium-based stabilizers such as lime on the geotechnical properties of tropical soils has been reported by many researchers. However, the amount of literature available on the micro-structural, molecular, and leaching characteristics of lime and in particular phosphoric acid-stabilized lateritic clays has been limited. This research was carried out in an attempt to identify the time-dependent soil-chemical reactions. In addition, the possible mechanisms that contributed to the stabilization process were discussed in the light of various spectroscopic and microscopic techniques such as X-ray diffractometry (XRD), energy-dispersive X-ray spectrometry (EDAX), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (NMR) etc. Based on the results it was found that in lime-treated samples, the coating action of free iron oxides on clay particles imposed inhibitive effects on the dissolution of clay alumina. On the other hand, in phosphoric acid-stabilized soil, due to the increase in solubility of metal oxides and also the subsequent release of clay alumina the formation of cementitious compounds were more feasible. From engineering point of view, the phosphoric acid-stabilized lateritic soil showed the highest degree of improvement with an approximately threefold strength.

]]> Amin Eisazadeh et al. Geotechnical engineering http://works.bepress.com/hadi_nur/53 http://works.bepress.com/hadi_nur/53 Sun, 02 May 2010 01:24:40 PDT The expansive nature of soils containing high amounts of clay minerals can be altered through chemical stabilization, resulting in a material suitable for construction purposes. The primary objective of this investigation was to study the changes induced in the molecular structure of phosphoric acid stabilized bentonite and lateritic soil using Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FTIR) spectroscopy. Based on the obtained data, it was found that a surface alteration mechanism was the main reason responsible for the improvement of treated soils. Furthermore, the results indicated that the Al present in the octahedral layer of clay minerals were more amenable to chemical attacks and also partly responsible for the formation of new products.

]]> Amin Eisazadeh et al. Geotechnical engineering http://works.bepress.com/hadi_nur/52 http://works.bepress.com/hadi_nur/52 Fri, 30 Apr 2010 07:48:28 PDT Dielectrical property on poly(methacrylic acid-ethylene glycol dimethacrylate) P(MAA-EDMA)] attached with nanosized CdS particles have been studied. The attachment of CdS nanoparticles alters the dielectric property of CdS-P(MAAEDMA) samples. By addition of a certain amount of CdS nanoparticles, the dielectric constant at room temperature and 100 Hz of the CdS-P(MAA-EDMA) is enhanced by ca. 500 times, which is attributed to the interfacial interaction of CdS nanoparticles with polymer surface. The large value of dielectric constant is due to interfacial space charge polarization.

]]> Hadi Nur et al. Materials Science http://works.bepress.com/hadi_nur/51 http://works.bepress.com/hadi_nur/51 Fri, 30 Apr 2010 07:39:12 PDT The expansive nature of soils containing high amounts of montmorillonite mineral can be altered through chemical stabilization, resulting in a material suitable for construction purposes. In this paper, the physicochemical behaviour of phosphoric acid treated samples was studied using X-ray Diffractometry (XRD), Energy Dispersive X-ray Spectrometry (EDAX), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), and Solid-State Nuclear Magnetic Resonance spectroscopy (SS-NMR). It was found that in acid stabilized montmorillonitic soil, clay alumina was more susceptible to dissolution and mostly responsible for the formation of aluminate phosphate hydrate compounds that bonded the soil particles together. Furthermore, since the action of stabilizer was mainly “surface-associated”, the efficiency of phosphoric acid treatment in terms of strength improvement was rather limited.

]]> Amin Eisazadeh et al. Geotechnical engineering http://works.bepress.com/hadi_nur/50 http://works.bepress.com/hadi_nur/50 Thu, 01 Apr 2010 17:03:17 PDT Enhancement of Brønsted acidity in silica-titania aerogel was achieved by loading both sulfate and vanadium onto the material. This phenomena could be due to formation of V(OSi)2OH-O-SO3 in the resulted sample. In contrast, no noticeable Brønsted acidity was detected in vanadium loaded silica-titania aerogel (V/ST). UV-vis DR analysis results showed that the amount of hydrated tetrahedral titanium species, which acts as oxidative site, increased significantly upon sulfation and vanadium loading on the surface of the aerogel. However, presence of vanadium in the samples tended to transform framework tetrahedral titanium to extra framework octahedral titanium structure. The catalytic performance of the samples were evaluated in consecutive transformation of 1-octene to 1,2-octanediol through formation of 1,2-epoxyoctane using aqueous H2O2.

]]> Siew Ling Lee et al. Heterogeneous catalysis http://works.bepress.com/hadi_nur/49 http://works.bepress.com/hadi_nur/49 Thu, 25 Feb 2010 07:41:51 PST Mesoporous alumina which contains only Lewis acidity was synthesized by sol-gel method and was then impregnated with sulfuric acid to generate Brönsted acidity. The catalyst was used in Friedel-Crafts alkylation of resorcinol with methyl tert-butyl ether to produce 4-tert-butylresorcinol and 4,6-di-tert-butylresor- cinol as the major and minor products respectively. It was demonstrated that Lewis and Brönsted acidities play a synergetic role in this reaction.

]]> Sheela Chandren et al. Heterogeneous catalysis http://works.bepress.com/hadi_nur/48 http://works.bepress.com/hadi_nur/48 Fri, 26 Jun 2009 03:52:05 PDT Heterogeneous asymmetric catalysts using amino acid as chiral promoter were synthesized by attachment of amino acids such as L-glutamic acid and L-phenylalanine onto the hydrophilic part of hydrolyzed octadecyltrichlorosilane (OTS). The catalysts exhibit 12-18% enantiomeric excess (ee) for the asymmetric hydration of epoxycyclohexene to yield (1R,2R)-trans-1,2-cyclohexanediol and (1S,2S)-trans-1,2-cyclohexanediol.

]]> Hadi Nur et al. Heterogeneous catalysis http://works.bepress.com/hadi_nur/47 http://works.bepress.com/hadi_nur/47 Fri, 26 Jun 2009 03:46:24 PDT The excellent catalytic performance of phosphate–vanadium impregnated silica–titania aerogel as a bifunctional oxidative and acidic catalyst was evaluated in consecutive transformation of 1-octene to 1,2-octanediol through formation of 1,2-epoxyoctane using aqueous H2O2. Phosphate group and vanadium were impregnated onto silica–titania aerogel via wet impregnation method at room temperature, followed by a high calcination temperature. Significant increase of hydrated, tetrahedrally coordinated Ti species was found in phosphate–vanadium impregnated silica–titania sample. Pyridine adsorption study revealed that the combination of phosphate group and vanadium is essential for generation of Brønsted acidic sites. Phosphate– vanadium impregnated silica–titania catalyst produced 1,2-octanediol (275 lmol) with selectivity of 65%. In contrast, no noticeable diol was produced when silica– titania aerogel and phosphate treated silica–titania sample were used.

]]> Lee Siew Ling et al. Heterogeneous catalysis http://works.bepress.com/hadi_nur/46 http://works.bepress.com/hadi_nur/46 Thu, 30 Apr 2009 10:46:01 PDT Bifunctional oxidative and acidic catalyst was prepared by incorporation of titanium ion (Ti4+) and niobic acid in zeolite molecular-sieve. Nb/TS-1 was prepared by hydrothermal synthesis of Titanium silicalite, TS-1, calcination in air and subsequent impregnation of niobium (3-20 wt% Nb2O5) into TS-1. Acidity of the sample was characterized by pyridine adsorption technique. Pyridine adsorption study shows both Brønsted and Lewis acid sites are present in all Nb/TS-1 samples.

]]> Didik Prasetyoko et al. Heterogeneous catalysis http://works.bepress.com/hadi_nur/44 http://works.bepress.com/hadi_nur/44 Thu, 05 Feb 2009 03:19:08 PST An NaY zeolite, modified with partly alkylsilane-covered titanium oxide and located at the boundary between aqueous and organic phases (a phase-boundary catalyst), acts as a catalyst for alkene epoxidation without stirring or the addition of a co-solvent to drive liquid–liquid phase transfer.

]]> Hadi Nur et al. Heterogeneous catalysis