Papers by Author: Viboon Sricharoenchaikul

Abstract: The steam reforming of toluene as a model compound of biomass gasification tar was carried out over Mg and La oxide-promoted Ni-metal oxide/Al2O3 catalysts. Catalysts were prepared by two different methods, co- and sequential impregnation. The findings indicate that conversion of gas products was improved with the use of prepared catalysts especially on syn-gas (H2 and CO) species and the highest conversions were obtained at the reaction temperature of 800°C. LHV’s of product gas when using catalysts at 800°C were over 4 MJ/m3 and ratios of H2 to CO were between 2.49-2.77. For long term test, Carbon and hydrogen conversion to CO and H2 of the catalysts with respect to time on stream in the steam toluene reforming for 480 min were studied. La2O3+MgO+Ni/Al2O3 catalyst revealed the highest and stable conversion rate of closely 50% and 70% for CO and H2, respectively. Whisker carbon species and encapsulating carbon were found on used catalysts after reaction. The La2O3+MgO+Ni/Al2O3 catalyst showed lesser amount of whisker carbon and encapsulating carbon.

Abstract: Currently solid wastes generated from manufacturing process of thermosetting composite have caused environmental problems because they are non biodegradable product and cannot be recycled or remolded due to chemically crosslinked. Thus, the aim of this research is to convert glass fiber reinforced epoxy composite waste to fuel gases by gasification process. The composite waste was first grounded and its thermal decomposition behavior was then investigated using isothermal thermogravimetric analysis (TGA) from an ambient to 900°C at heating rate of 10°C/min under nitrogen atmosphere. The results showed that major decomposition temperatures of the epoxy matrix were ranging from 300 to 450°C. The composite sample was then mixed with two different catalysts, olivine (LiFePO₄) or 10%NiAl₂O₃ in order to study the effect of catalyst on gas conversion efficiency before it was gasified in a fixed bed reactor at final temperature of 500, 600, 700, and 800°C under nitrogen mixed with air at total flow rate of 200 mL/min. Gasification process indicated that solid residues were mainly brittle black containing residual glass fiber. The significant increasing of carbon monoxide and carbon dioxide conversion was achieved from sample mixed with olivine catalyst at gasification temperature of 700°C, when compared with result without catalyst at baseline conversion of 500°C as. Therefore, it can be expected that gasification process is a promising method to deal with epoxy composite for producing renewable energy.

Abstract: Pyrolysis is one form of energy recovery process which has the potential to generate oil, gas and char products. The char becomes an attractive by-product, with applications including production of activated carbons that is useful as a sorbent for wastewater treatment and air pollution control. In this work, activated carbon was prepared from Coffee (Coffea Arabica L.) bean waste collected from local coffee houses. Char from pyrolysis of coffee bean waste at 900 °C contained high fixed carbon and low volatile content that was favorable for subsequent activation process. The char was activated via chemical treatment with sodium hydroxide (NaOH) at five different NaOH : char ratios (1:1, 2:1, 3:1, 4:1 and 5:1) and heat treated at 400°C for 15 minutes using a fixed bed reactor under nitrogen atmosphere with a flow rate of 100 mL/min. Result shows that NaOH works effectively as dehydration reagent around 400°C. Under the experimental conditions investigated, impregnation ratio of 1.0 was found to be suitable for producing high-surface area activated carbon. The surface area and total pore volume of activated carbons, which were determined by application of the Brunauer–Emmett–Teller (BET) and t-plot methods, were achieved as high as 802 m2/g and 0.80 cm3/g, respectively. The chemically activated carbons were found to be mainly type I carbons and had high adsorption property (Methylene blue adsorption = 284 mg/g and Iodine number = 1070 mg/g).

Abstract: Glycerol waste is by-product from the manufacturing of biodiesel by transesterification method containing impurities such as fatty acid, alcohol, spent catalyst, soap and water. Conversion of this waste to value added fuel products would not only improve economic of biodiesel production but also reduce environmental impact from this process. In this work, thermal conversion of glycerol waste by microwave that induced the heat required for initiating the reaction was carried out in a fixed bed quartz reactor using silicon carbide as the bed medium for microwave receptor as well as supporter for nickel catalyst. For non-catalytic reaction at 220W (700°C), carbon and hydrogen conversions were 22.89% and 19.59%, respectively. Gas production was 0.12 L/min syngas, 0.07 L/min H2, 0.82 MJ/m3 of LHV, and 1.27 H2/CO. In catalytic test, the highest syngas, H2, and LHV of 0.41 L/min, 0.23 L/min, and 9.18 MJ/m3, respectively, were obtained from 1%Ni/SiC while the highest H2/CO of 2.72 was obtained from 0.5%Ni/SiC. The 1%Ni/SiC test also resulted in the highest conversion of carbon and hydrogen as much as 79.50% and 83.26%, respectively. For comparison between fresh and regenerated catalysts, it was found that fresh catalyst performed significantly better that regenerated one in term of higher total conversion which may due to sodium deposition on spent catalyst surface.

Abstract: . La1-xCexCoO3 (x=0, 0.2, and 0.4) perovskite-type mixed oxides using polyvinyl alcohol (PVA) as complexing agent at two molar ratio of metal ion to PVA (1:1 and 1:2) were successfully prepared by sol-gel process. The precursor included lanthanum (II) nitrate hexahydrate, cerium (II) nitrate hexahydrate, and cobalt (II) nitrate hexahydrate where polyvinyl alcohol was added as complexing agent. The suitable condition of Cerium (Ce) substitution and PVA molar ratio were established for further application in hydrocarbon conversion to high value added products. TGA thermogram of as-prepared precursor showed that PVA absolutely decomposed at temperature higher than 500°C. XRD patterns of calcined catalyst showed both LaCoO3 rhombohedral and CeO2 cubic structures that confirmed the formation of mixed crystal structure. Nevertheless, Co3O4 slightly appeared with low peak intensity which came from the oxidation reaction of as-prepared catalyst during calcinations. XRD showed that PVA did not effect to crystal structure of synthesized catalyst. Higher PVA content added in the precursor cause the reduction of crystal growth of catalyst in calcinations step. In contrast, morphology of catalyst is directly related with PVA content such that the spongy and sheet-like structure were formed with increasing PVA content which prevented the agglomeration of particles. The results showed that PVA content play an important role in morphology of perovskite-type mixed oxide catalysts but did not affected to their crystal structures.

Abstract: Three types of unsaturated polyester matrix, ortho phthalic, iso phthalic, and vinyl ester, reinforced with glass fiber laminated composite waste have been subjected to investigate thermal decomposition behavior and kinetic parameters using non-isothermal thermogravimetric analysis from an ambient to temperature 900°C under nitrogen atmosphere at the passing flow rate of 20 ml/min. The results showed that the major decomposition range of the unsaturated polyester matrix was from 260 to 445°C, depending on a heating rate and the different types of polyester matrix. Regarding their chemical structure, ortho phthalic polyester started to degrade at lower temperature (260-280°C) than iso phthalic and vinyl ester (300-350°C). The remaining solid residual contained glass fiber which could not degrade under experimental conditions. The maximum rate of weight loss was increased with increasing heating rate. The activation energy for decomposition of ortho, iso phthalic, and vinyl ester composites was 168, 172, and 176 KJ/mol, respectively.

Abstract: Perovskite-type oxides catalyst are of interest for various application such as auto-thermal reforming (ART), catalytic wet air oxidation (CWOA) and piezoelectric (PZT). In this paper, La1-xCexNiO3 (x= 0-0.4) perovskite-type oxides have been prepared b sol-gel process using PVA. The precursor was mixed metal ion and PVA with a mole ratio of 1:1 and 1:2. The decomposition during the calcinations process was evaluated by thermogravimetric analysis and differential thermal analysis. Phase of synthesized materials were characterized with X-ray diffraction. Morphological analysis and elemental composition of catalysts was determined by Scanning electron microscope and energy dispersion spectroscopy. The characterization results show that highly crystalline and homogeneous phase of these perovskite oxides were successfully synthesized by the sol-gel method via PVA as a complexing agent.

Abstract: Deteriorated environment resulting from fossil fuel usage as well as foreseeable conventional energy depletion lead to the exploration of alternative fuel materials especially the renewable ones. In this work, characterization of synthetic fuel material formed by pelletization of Jatropha (physic nut) waste using glycerol waste as a binder was carried out in order to investigate the feasibility of utilizing these waste materials as another renewable energy source. Synthetic fuel materials of Jatropha residue mixed with 0-40% glycerol waste were formed to length of about 13 mm and diameter of about 11 mm under pressure of 7 MPa in a hydraulic press. Their thermal conversion properties were studied by using single particle reactivity testing scheme at temperature of 500-900°C under partial oxidation atmosphere. The burning started with a relative short drying phase, followed with a longer pyrolysis time and thereafter the dominated char combustion time which took around 81-89% of total conversion time. The average total conversion time varied from 741 sec to 1873 sec depended mainly on reaction temperature. Higher glycerol content resulted in char with lower density and less shrinkage. Changes in diameter were not strongly depended on glycerol contents. The results suggested that Jatropha residue mixed with glycerol may be utilized as quality solid fuel.

Abstract: Thermal decomposition characteristic of waste material from oil extraction of Jatropha (physic nut), including shell and kernel, was investigated using thermogravimetric analysis (TGA) and pyrolysis experiments. Effects of heating rate (5-90°C/min), reaction temperature (500-900°C) and hold time at final temperature (3-15 min) on the feature of thermogram, kinetic parameters as well as product distribution were evaluated. Thermal conversion of this residue composed of cellulose, hemicellulose, and lignin degradation steps with maximum weight losses around 250 to 450°C. The order of reaction increased with temperature from 0.28 at 250°C to 0.81 at 450°C. The activation energies ranging from 105-184 kJ/mol depend on the stage of devolatilization. The amount of gas product increased with temperature with the expense of reducing char and liquid from secondary heterogeneous cracking reactions. More than 14% of hydrogen in residue was converted to H2 during pyrolysis at 900°C. Major hydrocarbon gases are those of C4+ species with measurable amount of CH4 and C2 derivatives. Increase in reaction temperature can lead to a noticeable increase of hydrogen and hydrocarbon gas yields. Addition of catalyst and steam would promote the formation of fuel gas from this waste material.

Abstract: Char derived from pyrolysis of physic nut waste at 400-800°C was used for the preparation of activated carbon by chemical impregnation of phosphoric acid and potassium hydroxide. The original char exhibited the BET surface area in the range of 120-250 m2·g-1. The surface area increased to 480 and 532 m2·g-1 when activated with H3PO4 and KOH, respectively. Equilibrium adsorption data was found to be best represented by the Langmuir isotherm with maximum monolayer adsorption capacity of 560.13 mg·g-1 at 30°C. The adsorption capacity of the physic nut residue activated carbon was comparable to commercial activated carbon.