Papers by Keyword: Catalysis

Abstract: CO emission is one of biggest problem in environmental sector due to increasing number of motorcycle user in every years. CO is poison gas which directly affects on the public health and earth’s atmosphere. The aim of this research to developed catalyst in catalytic converter system to oxidize CO to CO₂ by using MnO₂/zeolite NaY. Zeolite NaY was synthesized by using hydrothermal method following by wet impregnation to form MnO₂/zeolite NaY, then the composite was characterized by XRD, FTIR, SEM-EDX, N₂ physisorption, and catalytic activity oxidation of CO was carried out using 4 tag motorcycle. The XRD result represent zeolite NaY synthetic has similar diffraction peak with zeolite NaY (JCPDS 39-1380), then infrared spectrum exhibit T-O-T at fingerprint area which exhibit vibration of zeolite NaY. Octahedral crystal was successfully observe by using SEM which represent zeolite NaY crystal similar with previous study. N₂ physisorp shows that the composite has type IV of isotherm which exhibit the micropore and mesopore was form into material. Then, MnO₂/zeolite NaY has good thermal stability as well as catalytic activity for CO oxidation, where the longer reaction time successfully to reduce the concentration of CO. Conversely, CO₂ concentration dramatically increase as function of reaction time.

Abstract: 1,2-Propanediol selective oxidation with molecular oxygen in presence of heterogeneous catalyst is one of the most nature friendly 1,2-propanediol conversion methods. This work demonstrates Au, Pt and Pd containing catalysts’ activity and selectivity in a 1,2-propanediol oxidation process. The main product of the 1,2-propanediol catalytic oxidation was lactic acid, by-products were acetic and formic acids. It was found that Au based catalysts are best for 1,2-propanediol oxidation in alkaline water solutions. The best result was achieved using the 4.8wt%Au/Al₂O₃ catalyst: selectivity by lactic acid was 94% with 1,2-propanediol conversion 100% (c₀(1,2-propanediol) = 0.3 mol/L, P(O₂) = 6 atm, n (1,2-propanediol)/n (Au) = 500, t = 60°C, c₀(NaOH) = 1.5 mol/L).

Abstract: Magnetic nanocomposites are multi-component, nanosized magnetic materials, to generate the response to an external stimulus (i.e., outer inert or alternative magnetic field). The novel nanocomposites is a combination of excess of various materials such as liquid crystals, silica, gels, renewable polymers, carbon along with different magnetic particles. They have immense applications in the field of medical diagnosis and therapy, catalysis and separation. These nanocarriers are mainly classified into nanotubes, nanosheets, spherical nanoparticles, nanofibres, highly porous nanocomposites. The porous nanostructures provides a better surface for the entrapment or covalent binding of enzymes, proteins, biomolecules and drugs but the major challenge is to design and synthesize a desired structure with suitable surface properties and biocompatibility. Extensive attempts have been made to manipulate the mesoporous materials and its combination with other structure in order to synthesize a matrix with appropriate pore size, large surface area to volume ratio. “Bottom-up” and “Bottom-down” chemical-based synthesis methods have been widely employed to prepare magnetic nanoparticles. Magnetic nanocomposites are synthesized from magnetic nanoparticles and biopolymers by using sol-gel technique, chemical precipitation methods and NanogenTM, a microwave plasma method. In this chapter, we described the advances and developments in the formation/synthesis of magnetic nanocomposites. This chapter will review the characteristics, properties and applications of the magnetic nanocomposites.

Abstract: Composites of Au supported on the TiO₂-nanofibers (Au/NF-TiO₂) were synthesized and tested in glycerol oxidation processes. TiO₂-nanofibers were prepared by a microwave-assisted hydrothermal synthesis method. Chemical deposition method was used for nanofibers modification with Au nanoparticles. Oxidation of aqueous glycerol solutions by molecular oxygen in the presence of Au/NF-TiO₂ nanocomposites was performed. It was found that Au/NF-TiO₂ composites are catalytically active in alkaline glycerol water solutions. The main product of glycerol catalytic oxidation was glyceric acid, by-products were – tartronic, lactic, glycolic, oxalic, acetic and formic acid. It was shown that Au/NF-TiO₂ catalysts’ activity and selectivity depend on Au weight loading, glycerol/Au molar ratio, oxygen pressure and NaOH initial concentration. The best result was achieved using the 0.5 wt%Au/NF-TiO₂ catalyst: selectivity by glyceric acid was 76% with glycerol conversion 100%.

Abstract: [bnmim]HSO₄ and [bnpy]HSO₄ are active and environmentally friendly catalysts for the acetylation of camphene with acetic acid. The reaction provides isobornyl acetate with 100% selectivity and 72-86% yield. The effect of temperature, molar ratio camphene/acetic acid, and catalyst loading were investigated. The catalyst can be reused four times without loss of activity. Isobornyl acetate is an important fine chemical and has been used in the field of fragrance, medicine, organic synthesis and cosmetics [1]. It is an intermediary in the synthesis of camphor [2]. Usually it is prepared by an acid-catalized reaction of camphene with acetic acid or acetic anhydride. But this process has serious drawbacks such as the corrosion of equipment, non-recyclability of the catalyst and serious environmental pollution. In the face of increasing environmental requirements, the use of such catalysts becomes unacceptable. Therefore many studies have recently focused on the development of "clean" (green) processes for the production of terpene derivatives with high selectivity. For this purpose, heteropolyacids [3, 4], zeolites [5, 6], solid acid catalysts [7, 8], ion-exchange resin [9-11] were used as catalysts for synthesizing terpene esters. However, these catalysts have drawbacks such as a large ratio of catalyst/substrate, fast deactivation and a selectivity that leaves much to be desired. In the recent years ionic liquids (IL) have been investigated by many researchers as catalysts for different reactions. Due to its low volatility, negligible vapor pressure, reasonable thermal stability, outstanding recyclability and reusability, ionic liquids may be a viable alternative to widely applicable catalysts in the processes of modern synthetic chemistry, the green chemistry [12]. The improvement of the versatility of ionic liquids was achieved by creating acidic functionalized ionic liquids and combining the properties of a reagent and solvent [13]. A number of such ionic liquids were synthesized and successfully applied in the esterification reaction [14-17]. Received that the structure of the IL cation determines the direction of the rearrangement of terpene, whereas the nature of the anion affects the selectivity of the reaction [18, 19]. In the present work, we report the acetylation of camphene with acetic acid catalyzed by imidazolium and pyridinium ionic liquids (Scheme 1). The influence of various reaction parameters, such as the temperature, the molar ratio of camphene/acetic acid and catalyst loading, on the activity of the most active catalyst is also studied.

Abstract: In this work the Fischer-Tropsch synthesis reaction was catalyzed by reduced graphene oxide supported Fe nanoparticles catalysts in a fixed bed reactor. Also the influence of promotion by K and Mn on the catalytic activity of Fe nanoparticles was investigated. The systems showed acceptable CO conversions reaching as high as 96.2%. The selectivities of the C_1-5 ranged from 38 to 62%. There was a very high CO₂ selectivity which was explained by incomplete reduction of the catalysts. The Anderson-Schultz-Flory parameter was calculated and varied between 0.25 and 0.3. The strongest promoting effect was achieved by the K promoter which tended to reduce light product selectivities and CO₂ production the most.

Abstract: Magnetic Ionic liquids are a class of functional ionic liquids with magnetic. Because of outstanding thermal stability, excellent electrochemical properties, good solubility and recyclability, it has broad application prospects in catalysis, separation extraction, material synthesis and other fields. The main applications of magnetic ionic liquids in recent years are reviewed especially in the field of magnetic separation and catalytic. It shows a huge advantage that can highly efficiently catalyze myriads of reactions, and can be recovered and reused by a magnetic field. With the further research of magnetic ionic liquids, it is believed that the magnetic ionic liquid will be applied in more fields.

Abstract: Two kinds of Pt/CeO₂ catalysts supplemented with NiO or CoO_x additives were synthesized by extractive-pyrolytic method and tested in glycerol oxidation processes. It was found that only NiO additive promotes Pt/CeO₂ catalysts activity and selectivity to glyceric acid. NiO promoted Pt catalysts activity depends on NiO composites’ calcination temperature, oxygen partial pressure, initial NaOH concentration, as well as temperature. Glycerol conversion increases along with increased oxygen partial pressure from1 to 6 atm and along with decreased glycerol/Pt molar ratio from 5000 to 300. It was found that presence of base is significant in the glycerol oxidation processes over NiO promoted Pt/CeO₂ catalysts, and optional NaOH initial concentration is 0.6 mol/L. The best yield of glyceric acid (68%) was reached in the presence of 4.8wt%Pt/5wt%NiO/CeO₂ (300 °C) catalyst, when temperature was elevated up to 70 °C.

Abstract: The reaction of Re₂O₇ with a mixed non-aqueous medium S₂Br₂+Se₂Br₂ at 100 °C gives Re₃Se₃S₄Br₁₃: own structure type, Z = 4, space group Pnma – d ⁹c ⁵, a = 14.0301(4), b = 17.7909(4), c = 10.8596(3) Å, R_I = 0.0491. The crystal structure can be described as a 3D-packing of isolated trinuclear cluster molecular cation-anionic complexes [Re₃(µ₃-S)(µ-S)₃(SeBr₂)₃Br₆]⁺Br^–. This compound displays a high catalytic activity in the hydrogenation of m-nitrobenzoic acid into m-aminobenzoic acid with 93 % yield in 5 % HBr aqueous solution.

Abstract: Empty fruit bunch (EFB) waste is produced in large amount in Malaysia from intense oil palm agriculture activity. Direct usage of EFB as a source of energy is not economically feasible and ideally should be upgraded before it can produce green energy economically. Current gasification processes produces a lot of tar while yielding low amount of hydrogen. Flash gasification of EFB with the presence of catalysts shows improvements over the uncatalysed reaction. In this study, by using a high surface area support catalyst of ZSM-5 with the presence of 1% Ni, Zn, or Fe metal loading is sufficient to enhance the hydrogen production. ZSM-5, NiO/ZSM-5, CuO/ZSM-5, Fe₂O₃/ZSM-5 and ZnO/ZSM-5 catalyst with 1 wt % loading were prepared via the wet impregnation method. XRD patterns of the prepared catalysts shows almost identical peaks patterns which indicates high dispersion of dopants on the support catalyst Flash gasification was carried out at 900°C under isothermal heating conditions with 10 sccm 4.99% O₂ diluted in He. Syngas produced was then analysed using an online quadrupole mass spectrometer. Catalytic activity for hydrogen production is the highest for NiO/ZSM-5 followed by ZnO/ZSM-5, Fe₂O₃/ZSM-5, ZSM-5.