Now showing 1 - 10 of 17
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Alternative Hydrocarbon Biofuel Production via Hydrotreating under a Synthesis Gas Atmosphere
    (2017-11-16)
    Pongsiriyakul, Kanokthip
    ;
    Kiatkittipong, Worapon
    ;
    ;
    Laosiripojana, Navadol
    ;
    Faungnawakij, Kajornsak
    Direct use of syngas, a cheaper hydrogen-rich gas, instead of pure hydrogen, as a deoxygenating agent for biohydrogenated diesel (BHD) production is presented in this study. Low-cost palm fatty acid distillate (PFAD), an inedible byproduct from refining palm oil, is used as a feedstock in the presence of a Pd/C catalyst. The results indicate that syngas can be effectively used in BHD production, while the achieved BHD yield is slightly lower than that obtained from pure hydrogen. The liquid products contain mostly n-C<inf>15</inf> and n-C<inf>17</inf>, which fall into a diesel range. Decarbonylation is a prominent pathway under both hydrogen and syngas atmospheres. It was found that CO in syngas can act as a reducing agent, which can remove an oxygen atom from fatty acid molecules to form alkenol that could be further reduced to alkene and then cyclized to cycloparaffins. After reactivation, the activity of the catalyst could be fully recovered for at least 4 reused cycles. Reaction pathways for the catalytic deoxygenation under syngas are also proposed with the underlying mechanism on the role of CO.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Hydrogen production from catalytic supercritical water reforming of glycerol with cobalt-based catalysts
    (2013-04-15)
    Pairojpiriyakul, Thirasak
    ;
    Croiset, Eric
    ;
    Kiatkittipong, Worapon
    ;
    ;
    Arpornwichanop, Amornchai
    Glycerol reforming under catalytic supercritical water at temperatures in the range of 723-848 K using Co catalyst deposited on various supports including ZrO<inf>2</inf>, yttria-stabilized zirconia (YSZ), La<inf>2</inf>O<inf>3</inf>, γ-Al<inf>2</inf>O<inf>3</inf>, and α-Al<inf>2</inf>O<inf>3</inf> was investigated. An increase in operating temperature promoted the continued increase in glycerol conversion; however, carbon formation causing system operation failure was observed for γ-Al<inf>2</inf>O<inf>3</inf> and α-Al<inf>2</inf>O<inf>3</inf> at high operating temperatures (i.e. 748-798 K). Co supported on YSZ provided the most efficient performance for hydrogen production. 10 wt.% Co loading on YSZ support was an optimum amount to enhance the reaction. The increase in glycerol conversion and reduction of the amount of liquid products were observed for lower weight hourly space velocity (WHSV), higher operating temperature or higher cobalt loading. On Co/YSZ catalyst, glycerol conversion of 0.94 and hydrogen yield of 3.72 was obtained with WHSV of 6.45 h<sup>-1</sup>at 773 K. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Oil extracted from spent coffee grounds for bio-hydrotreated diesel production
    (2016-10-15)
    Phimsen, Songphon
    ;
    Kiatkittipong, Worapon
    ;
    Yamada, Hiroshi
    ;
    Tagawa, Tomohiko
    ;
    Oil extracted from spent coffee grounds is utilized as a renewable source for bio-hydrotreated fuel production. In the present work, oil yield up to 13% can be obtained by Soxhlet extraction with hexane as a solvent. As the extracted oil contained high content of free fatty acids (6.14%), therefore one step alkali-catalyzed for ester based biodiesel production is impractical. Hydrotreating of extracted oil was performed over two catalysts i.e. NiMo/γ-Al<inf>2</inf>O<inf>3</inf> and Pd/C with different operating parameters i.e. reaction time, operating temperature, and H<inf>2</inf>/oil. It was found that the reaction time of 2 h and the reaction temperature of 400 °C are favorable operating conditions. The liquid products mostly consisted of n-pentadecane and n-heptadecane, which contain one carbon atom shorter than the corresponding fatty acid (C<inf>n−1</inf>) i.e. palmitic and stearic acid, respectively. Unfavorable cracking of diesel product is pronounced at high temperature and prolonged reaction time. In addition, although increased H<inf>2</inf>/oil promoted overall reaction and hydrodeoxygenation activity (C<inf>n−1</inf>/C<inf>n</inf> decreased) for both catalysts, hydrocracking is enhanced over Pd/C, leading to significant increase in gasoline yield. Moreover, Pd/C gave higher olefin content in liquid product (22.3 wt%) than NiMo/γ-Al<inf>2</inf>O<inf>3</inf> (4.8 wt%). However, NiMo/γ-Al<inf>2</inf>O<inf>3</inf> shows higher isomerization activity. The amount of isoparaffins catalyzed by NiMo/γ-Al<inf>2</inf>O<inf>3</inf> and Pd/C were 10.8 and 1.7 wt%, respectively. Physiochemical analysis of the diesel fraction exhibit satisfactory properties. The density and kinematic viscosity were consistent with the specification of commercial bio-hydrogenated diesel, NExBTL, while the cetane index was much higher than conventional diesel.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Heat transfer enhancement of TiO2/water nanofluid in a heat exchanger tube equipped with overlapped dual twisted-tapes
    (2015-09-01)
    Eiamsa-ard, S.
    ;
    ;
    Titanium dioxide (TiO<inf>2</inf>) in water as nanofluid was employed for heat transfer enhancement together with overlapped dual twisted tapes (O-DTs). The study encompassed Reynolds numbers from 5400 to 15,200, O-DTs with overlapped twist ratios (y<inf>o</inf>/y) of 1.5, 2.0 and 2.5 and nanofluids with TiO<inf>2</inf> volume concentrations (ϕ) of 0.07%, 0.14% and 0.21%. The experimental and numerical results indicated that O-DTs with smaller overlapped twisted ratio delivered a stronger swirl intensity and higher turbulent kinetic energy (TKE). The use of O-DTs at the smallest overlapped twist ratio of 1.5 enhanced heat transfer rates up to 89%, friction factor by 5.43 times and thermal performance up to 1.13 times as compared to those of plain tube. In addition, heat transfer increased as TiO<inf>2</inf> volume concentration of nanofluid increased, owing to the increases of contact surface and thermal conductivity. The simultaneous use of the O-DTs having twist ratios 1.5 with the nanofluid with TiO<inf>2</inf> volume concentration of 0.21% resulted in heat transfer enhancement around 9.9–11.2% and thermal performance improvement up to 4.5% as compared to the use of O-DTs alone. The empirical correlations of heat transfer rate (Nu), friction factor (f) and thermal performance (η) in a constant wall heat flux tube equipped O-DTs at different overlapped twist ratios (y<inf>o</inf>/y) and volume concentrations of TiO<inf>2</inf> nanoparticles (ϕ) are also reported for heat transfer applications.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Photocatalysis of heat treated sodium- and hydrogen-titanate nanoribbons for water splitting, H2/O2 generation and oxalic acid oxidation
    (2013-04-09) ;
    Iwase, Akihide
    ;
    Scott, Jason
    ;
    Amal, Rose
    The photocatalytic activity of sodium titanate (Na<inf>1.48</inf>H<inf>0.52</inf>Ti<inf>3</inf>O<inf>7</inf>), sodium hexatitanate (Na<inf>2</inf>Ti<inf>6</inf>O<inf>13</inf>), and hydrogen titanate (H<inf>2</inf>Ti<inf>3</inf>O<inf>7</inf>) nanoribbons and anatase TiO<inf>2</inf> nanorods were compared for water splitting, oxalic acid photodegradation and H<inf>2</inf> and O<inf>2</inf> generation using sacrificial agents. The intrinsic properties of the materials were found to affect their performance depending on the particular reaction system. The Na<inf>2</inf>Ti<inf>6</inf>O<inf>13</inf> nanoribbons, in the presence of RuO<inf>2</inf> co-catalyst, outperformed the anatase nanorods, for the water splitting reaction, generating over 10 times more H<inf>2</inf>/O<inf>2</inf>. This was thought to derive from their tunnel-like structure which provided better electron/hole separation when compared with TiO<inf>2</inf>. However, the efficient holes and electrons scavenging in the presence of sacrificial agents, methanol or AgNO<inf>3</inf>, to generate H<inf>2</inf> or O<inf>2</inf>, respectively, overwhelmed the tunnel-like structure effect. In this case photoactivity was governed by the crystal structure, with observed decreasing activity in the order TiO<inf>2</inf>>Na<inf>2</inf>Ti<inf>6</inf>O<inf>13</inf>>H<inf>2</inf>Ti<inf>3</inf>O<inf>7</inf>~Na<inf>1.48</inf>H<inf>0.52</inf>Ti<inf>3</inf>O<inf>7</inf>, and by the band gap of the semiconductor which determined its capacity to absorb photons in producing electron/hole pairs. © 2013 Elsevier Ltd.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Preparation and characterization of the Na2Ti3O7: ABS/Na2Ti3O7 composites
    (2017-01-01)
    Sangkatip, Rittichai
    ;
    ;
    Titanate Ribbon (Na<inf>2</inf>Ti<inf>3</inf>O<inf>7</inf>) used in ABS plastic was synthesized to study the mechanical properties and to conduct test on the E-coli bacteria inhibition performance. The polymer blends of ABS/Na<inf>2</inf>Ti<inf>3</inf>O<inf>7</inf> by Na<inf>2</inf>Ti<inf>3</inf>O<inf>7</inf>, was synthesized through alkaline hydrothermal reaction with 0.5 grams of titanium dioxide as a precursor with 20 ml. of sodium hydroxide (NaOH) at the concentration of 10 molar under the alkalinity at 200°c for 24 hours. The study on the microstructure by scanning electron microscope revealed that the Layered structure was shaped as a complete ribbon. The mechanical testing activities on the E-coli bacteria inhibition polymer mixed ABS/Na<inf>2</inf>Ti<inf>3</inf>O<inf>7</inf>; it was found that the mechanical properties for ABS/Na<inf>2</inf>Ti<inf>3</inf>O<inf>7</inf>, The results showed that tensile modulus and tensile strength of blending Na<inf>2</inf>Ti<inf>3</inf>O<inf>7</inf> at 0.5 %wt was the highest. The result showed that E.coli could reduce up to 66.01%.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Liquid-Liquid Phase Equilibria of Aqueous Biphasic Systems Based on Glycerol Formal: Application on Tetracycline Recovery from Water
    (2019-11-14)
    Praikaew, Wanichaya
    ;
    Kiatkittipong, Worapon
    ;
    ;
    Assabumrungrat, Suttichai
    ;
    Aiouache, Farid
    Biopharmaceuticals are commonly present in relatively low concentrations in aqueous solutions, making their detection and purification detrimental. In this work, we used novel aqueous biphasic systems based on glycerol formal (GF) to extract an important antibiotic-tetracycline. We report cloud points (solubility curve) and tie-lines for three ternary systems, containing GF, water, and inorganic salt (either K<inf>3</inf>PO<inf>4</inf>, K<inf>2</inf>HPO<inf>4</inf>, or K<inf>2</inf>CO<inf>3</inf>) at constant temperature of 298 K and at 0.1 MPa. The tie-line data of these ternary systems were correlated using the nonrandom two-liquid model, and binary interaction parameters of activity coefficients were estimated. The experimental and correlated tie-line data were compared in terms of average root-mean-square deviation and showed satisfactory agreements. The partition coefficients of tetracycline between two phases were measured, and corresponding extraction efficiencies were calculated. The maximum value of partition coefficient was 1551 for the system containing K<inf>3</inf>PO<inf>4</inf>, followed by values of 1145 and 927 for systems containing K<inf>2</inf>CO<inf>3</inf> and K<inf>2</inf>HPO<inf>4</inf>, respectively. The calculated extraction efficiencies were very high-greater than 98.8%, demonstrating high potential for using aqueous biphasic systems based on GF for separation and purification processes.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Epoxidation of methyl oleate in a TiO2 coated-wall capillary microreactor
    (2017-01-01)
    Phimsen, Songphon
    ;
    Yamada, Hiroshi
    ;
    Tagawa, Tomohiko
    ;
    Kiatkittipong, Worapon
    ;
    In the present work, a catalytic coated-wall microreactor was developed and tested for producing epoxidized methyl oleate in a solvent-free system. TiO<inf>2</inf>was coated inside the microcapillary reactor wall by a static method, while H<inf>2</inf>O<inf>2</inf>and ethylenediaminetetraacetic acid (EDTA) were used as oxidant and stabilizer, respectively. The weight percent of oxirane oxygen was determined according to ASTM D1652 and the reaction performance was evaluated as oxirane oxygen yield and selectivity. Without TiO<inf>2</inf>coated catalyst or formic acid, trace oxirane yield were obtained. Without EDTA as stabilizer, decomposition of H<inf>2</inf>O<inf>2</inf>occurred as bubbles formation causing system operation failure. The results indicated that TiO<inf>2</inf>coated catalyst as well as the presences of EDTA and formic acid were crucial for epoxidation reaction, and oxirane yield of 43.1% could be achieved at the optimal reaction temperature of 60 °C and residence time of 2.7 min. The results were compared with the data obtained from a batch reactor. Microcapillary reactor offers continuous operation with 23 times higher reaction rate of epoxide production than batch reactor. However, TiO<inf>2</inf>coated layer was partially peeled off over 3 h lead to decrease in epoxide yield.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Heat transfer enhancement by multiple twisted tape inserts and TiO 2/water nanofluid
    (2014-09-05)
    Eiamsa-Ard, Smith
    ;
    The aim of this present work is to enhance thermal performance characteristics in a heat exchanger tube by studying: (i) multiple twisted tapes in different arrangements; (ii) TiO<inf>2</inf> nanoparticles with different concentrations as the working fluid. The tube inserted the multiple twisted tapes showed superior thermal performance factor when compared with plain tube or the tube inserted a single twisted tape, due to continuous multiple swirling flow and multi-longitudinal vortices flow along the test tube. The higher number of twisted tape inserts led to an enhancement of thermal performance that resulted from increasing contact surface area, residence time, swirl intensity and fluid mixing with multi-longitudinal vortices flow. Moreover, arrangement of twisted tapes in counter current was superior energy saving devices for the practical use, particularly at low Reynolds number. This was especially the case for quadruple counter tapes in the cross directions (CC-QTs) where heat transfer enhancement with relatively low friction loss penalty was deserved. The use of CC-QTs led to the highest thermal performance factor up to 1.45. Using water with TiO<inf>2</inf> nanoparticle as a working fluid yielded a higher thermal performance than using pure water. The tube inserted CC-QTs with TiO<inf>2</inf>/water nanofluid at concentration of 0.21% by volume provided the highest thermal performance factor 1.59, where heat transfer rate and friction factor increased to 3.52 times and 11.7 times of those in the plain tube with water as the working fluid. © 2014 Elsevier Ltd. All rights reserved.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Catalytic reforming of glycerol in supercritical water with nickel-based catalysts
    (2014-09-12)
    Pairojpiriyakul, Thirasak
    ;
    Croiset, Eric
    ;
    ;
    Kiatkittipong, Worapon
    ;
    Arpornwichanop, Amornchai
    The catalytic performance of nickel catalysts supported on La <inf>2</inf>O<inf>3</inf>, α-Al<inf>2</inf>O<inf>3</inf>, γ-Al <inf>2</inf>O<inf>3</inf>, ZrO<inf>2</inf>, and YSZ for supercritical water reforming of glycerol was investigated. Experiments were conducted in a tubular reactor made of Inconel-625 with the temperature range of 723-848 K under a pressure of 25 MPa. Carbon formation causing operation failure was observed for α-Al<inf>2</inf>O<inf>3</inf>, γ-Al<inf>2</inf>O<inf>3</inf> and ZrO<inf>2</inf> at temperatures higher than 748, 798 and 823 K, respectively. Ni/La<inf>2</inf>O<inf>3</inf> exhibited the highest H<inf>2</inf> yield where almost complete conversion was obtained at 798 K. Moderate space velocities (WHSV = 6.45 h<sup>-1</sup>) and glycerol feed concentration (5wt.%) favor high hydrogen selectivity and yield. Methanation is favored at a low WHSV or high glycerol feed concentration, resulting in a lower H<inf>2</inf> yield. Increasing Ni loading on the Ni/La<inf>2</inf>O<inf>3</inf> catalyst strongly promoted the reforming, water-gas shift, and methanation reactions, which contributed significantly to the product species distribution. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.