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    Alternative Hydrocarbon Biofuel Production via Hydrotreating under a Synthesis Gas Atmosphere
    (2017-11-16)
    Pongsiriyakul, Kanokthip
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    Kiatkittipong, Worapon
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    Laosiripojana, Navadol
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    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.
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    Oil extracted from spent coffee grounds for bio-hydrotreated diesel production
    (2016-10-15)
    Phimsen, Songphon
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    Kiatkittipong, Worapon
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    Yamada, Hiroshi
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    Tagawa, Tomohiko
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    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.
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    Mechanism of CaO catalyst deactivation with unconventional monitoring method for glycerol carbonate production via transesterification of glycerol with dimethyl carbonate
    (2022-02-01)
    Praikaew, Wanichaya
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    Kiatkittipong, Worapon
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    Aiouache, Farid
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    Najdanovic-Visak, Vesna
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    Termtanun, Mutsee
    Glycerol carbonate (GC) was synthesized by transesterification of glycerol with dimethyl carbonate (DMC) using calcium oxide (CaO) derived from eggshell as a catalyst. The best results of 96% glycerol conversion and 94% GC yield were achieved under the following reaction conditions: 0.08 mole ratio of CaO to glycerol, 1:2.5 mole ratio of glycerol to DMC, 60°C reaction temperature, and 3 hours reaction time. As expected, CaO showed deteriorated catalytic performance when recycling as observed by a rapid decrease in GC yield. This research showed that the active CaO phase first was converted to calcium methoxide (Ca[OCH<inf>3</inf>]<inf>2</inf>) and calcium diglyceroxide (Ca[C<inf>3</inf>H<inf>7</inf>O<inf>3</inf>]<inf>2</inf>) and finally to carbonate phase (CaCO<inf>3</inf>) which can be confirmed by XRD patterns. According to the phase transformation, the basicity decreased from 0.482 mmol/g to 0.023 mmol/g, and basic strength altered from strong basic strength (15.0 < H_ < 18.4) to weak basic strength (7.2 < H_ < 9.8), resulting in the lower catalytic activity of the consecutive runs. Despite the fact that the GC selectivity was almost 100%, the reaction products (methanol and GC) were not obtained in their stoichiometric ratio and their extents corresponded with that of the catalyst phase transformation to CaCO<inf>3</inf>. The mechanism of CaO catalyzed transesterification based on the condensation reaction of glycerol and catalyst was proposed, and in situ formation of water-derivative species was hypothesized as a cause of CaO transformation. CaO could react with DMC and water, generating methanol and CaCO<inf>3</inf>. This enabled unconventional monitoring of catalyst deactivation by checking if the mole ratio of methanol to GC was higher than 2:1 of its reaction stoichiometric ratio. It was also demonstrated that calcination of post-run catalyst at 900°C to CaO exhibited almost constant catalytic activity, and the mole ratio of methanol to GC was constant at its reaction stoichiometry (2:1) for at least 4 times use.
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    Effective Cu/Re promoted Ni-supported γ-Al2O3 catalyst for upgrading algae bio-crude oil produced by hydrothermal liquefaction
    (2021-06-01)
    Pongsiriyakul, Kanokthip
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    Kiatkittipong, Worapon
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    Adhikari, Sushil
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    Lim, Jun Wei
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    Lam, Su Shiung
    Catalytic hydrotreating of algae bio-crude oil from hydrothermal liquefaction (HTL) of Nannochloropsis sp. was performed. Different Ni-based catalysts, including Ni/γ-Al<inf>2</inf>O<inf>3</inf>, Ni-Cu/γ-Al<inf>2</inf>O<inf>3,</inf> Ni-Re/γ-Al<inf>2</inf>O<inf>3,</inf> and Ni-Cu-Re/γ-Al<inf>2</inf>O<inf>3,</inf> (10%Ni, 5%Cu, 2.5%Re) were used in upgrading of the bio-crude oil. Most catalytic systems could effectively eliminate S and decrease the N and O contents, and enhance more than 20% improvement in the higher heating value (HHV) of the bio-oil (34 to 41–45 MJ/kg). Introducing only Cu could enhance the C[dbnd]O hydrogenation resulting in higher aromatic and alcohol compounds. While the addition of Re is effective for hydrodeoxygenation, it lowers denitrogenation due to amination reaction. Ni-Cu-Re/γ-Al<inf>2</inf>O<inf>3</inf> ternary alloy offered the best results on the overall performance, achieving the highest upgraded bio-oil yield of 58 wt% and the highest energy recovery in the upgrading process (ER<inf>upgrade</inf>) of 64.6%. As ER in HTL process (ER<inf>HTL</inf>) was ca. 71.8%, the overall ER (ER<inf>overall</inf>) from algae biomass to upgraded bio-oil of 46.4% can be achieved for Ni-Cu-Re/γ-Al<inf>2</inf>O<inf>3</inf> catalyst. Carbon efficiency approx. 47.7% can be attained as the carbon in the algae biomass feedstock was retained in the upgraded bio-oil. In addition, reaction pathways for the formation of different hydrotreated products catalyzed by mono-, bi-, and tri- metallic Ni-Cu-Re have been proposed.
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    Process and energy intensification of glycerol carbonate production from glycerol and dimethyl carbonate in the presence of eggshell-derived cao heterogeneous catalyst
    (2021-07-02)
    Praikaew, Wanichaya
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    Kiatkittipong, Worapon
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    Aiouache, Farid
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    Najdanovic-Visak, Vesna
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    Ngaosuwan, Kanokwan
    The process and energy intensifications for the synthesis of glycerol carbonate (GC) from glycerol and dimethyl carbonate (DMC) using an eggshell-derived CaO heterogeneous catalyst were investigated. The transesterification reaction between glycerol and DMC was typically limited by mass transfer because of the immiscible nature of the reactants. By varying the stirring speed, it was observed that the mass transfer limitation could be neglected at 800 rpm. The presence of the CaO solid catalyst made the mass transport-limited reaction process more prominent. Mass transfer intensification using a simple kitchen countertop blender as an alternative to overcome the external mass transfer limitation of a typical magnetic stirrer was demonstrated. A lower amount of the catalyst and a shorter reaction time were required to achieve 93% glycerol conversion or 91% GC yield, and the turnover frequency (TOF) increased almost 5 times from 1.5 to 7.2 min<sup>−1</sup> when using a conventional magnetic stirrer and countertop blender, respectively. In addition, using a simple kitchen countertop blender with 7200 rpm, the reaction temperature of 60<sup>◦</sup>C could be reached within approximately 3 min without the need of a heating unit. This was the result of the self-frictional heat generated by the high-shear blender. This was considered to be heat transfer intensification, as heat was generated locally (in situ), offering a higher homogeneity distribution. Meanwhile, the trend toward energy intensification was promising as the yield efficiency increased from 0.064 to 2.391 g/kJ. A comparison among other process intensification techniques, e.g., microwave reactor, ultrasonic reactor, and reactive distillation was also rationalized.
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    Epoxidation of methyl oleate in a TiO2 coated-wall capillary microreactor
    (2017-01-01)
    Phimsen, Songphon
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    Yamada, Hiroshi
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    Tagawa, Tomohiko
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    Kiatkittipong, Worapon
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    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.
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    Synthesis of glycerol carbonate from dimethyl carbonate and glycerol using CaO derived from eggshells
    (2018-08-14)
    Praikaew, Wanichaya
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    Kiatkittipong, Worapon
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    Laosiripojana, Navadol
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    Viriya-Empikul, Navin
    Waste eggshell is proposed as a highly active catalyst for glycerol carbonate production from dimethyl carbonate (DMC) and glycerol. The effect of reaction temperature, reaction time and catalyst loading on the reaction performance were investigated in order to find a suitable operating condition. CaO derived from waste eggshell exhibits catalytic activity comparable to commercial CaO. By using CaO eggshell, glycerol conversion of 96% can be achieved within 90 min of reaction time under 2.5:1 feed molar ratio of DMC to glycerol, 0.08 mole ratio of CaO to glycerol and reaction temperature of 60°C. The catalyst was examined by XRD, TGA/DSC, SEM, N2 adsorption-desorption and Hammett indicators method. Utilization of eggshell as a catalyst for glycerol carbonate production not only provides a cost-effective and value-added of waste eggshell as a green catalyst, but also decrease amount of waste and its treatment cost which is ecologically friendly.
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    Diesel-like hydrocarbon production from hydroprocessing of relevant refining palm oil
    (2013-05-22)
    Kiatkittipong, Worapon
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    Phimsen, Songphon
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    Wongsakulphasatch, Suwimol
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    Laosiripojana, Navadol
    This paper demonstrates the initiated use of relevant refining palm oil for bio-hydrogenated diesel production. The conversions of crude palm oil (CPO) and its physical refining including degummed palm oil (DPO) and palm fatty acid distillate (PFAD) to diesel fuel by hydroprocessing were studied. The effects of operating parameters (i.e. reaction time, operating temperature, and pressure) and catalyst (i.e. Pd/C and NiMo/γ-Al<inf>2</inf>O<inf>3</inf>) were examined in order to determine suitable operating condition for each feedstock. It was found that the hydroprocessing of CPO with Pd/C catalyst at 400 C, 40 bar, and reaction time of 3 h provides the highest diesel yield of 51%. When gum which contains phospholipid compounds is removed from CPO, namely DPO, the highest diesel yield of 70% can be obtained at a shorter reaction time (1 h). In the case of PFAD, which consists mainly of free fatty acids, a maximum diesel yield of 81% could be observed at milder conditions (375 C with the reaction time of 0.5 h). The main liquid products are n-pentadecane and n-heptadecane, having one carbon atom shorter than the corresponding fatty acids according to decarboxylation/decarbonylation pathways. Pd/C catalyst shows good catalytic activity for fatty acid feedstocks but becomes less promising for triglyceride feedstocks when compared to NiMo/γ-Al<inf>2</inf>O<inf>3</inf>. © 2013 Elsevier B.V.
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    Xylitol and gluconic acid productions via photocatalytic-glucose conversion using TiO2 fabricated by surfactant-assisted techniques: Effects of structural and textural properties
    (2017-08-01)
    Payormhorm, Jiraporn
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    Chuangchote, Surawut
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    Chiarakorn, Siriluk
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    Laosiripojana, Navadol
    High-value chemicals can be converted from biomass and its derivatives by various methods. In this work, gluconic acid was obtained from photocatalytic conversion of glucose with synthesized TiO<inf>2</inf>. Moreover, another high-value chemical, xylitol, was firstly found from the photocatalysis in this work. Arabinose and formic acid are other co-products obtained from the reactions. Two surfactants, polyethylene glycol (PEG) and cetyltrimethylammonium bromide (CTAB), were used in conventional sol-gel (SG), ultrasonication sol-gel (US), and hydrothermal (HD) methods to fabricate TiO<inf>2</inf> with different structural and textural properties. Appropriate surface area and phase composition of TiO<inf>2</inf> for production of the highest yields of gluconic acid and xylitol were investigated. It was found that all surfactant-assisted fabrications increased surface area and anatase content of TiO<inf>2</inf> photocatalysts, resulting in high glucose conversion and high yields of xylitol, arabinose and formic acid. The highest yield of xylitol (6.45%) was obtained from US/CTAB-TiO<inf>2</inf>. Unfortunately, the yield of gluconic acid did not increase by increasing time, because it was also decomposed during photocatalysis. The moderate photocatalysis was found from SG/PEG-TiO<inf>2</inf> (100% anatase, surface area 5.93 m<sup>2</sup>/g) that provided the highest yield of gluconic acid (7.6%) in 120 min.
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    Nickel sulfide, nickel phosphide and nickel carbide catalysts for bio-hydrotreated fuel production
    (2017-11-01)
    Phimsen, Songphon
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    Kiatkittipong, Worapon
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    Yamada, Hiroshi
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    Tagawa, Tomohiko
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    A series of nickel catalysts i.e. nickel sulfide (NiS), nickel phosphide (NiP) and nickel carbide (NiC) was investigated for hydrotreating of spent coffee oil to produce bio-hydrotreated fuel (BHF). Catalytic tests were carried out at 375–425 °C and 20–40 bar of initial H<inf>2</inf> pressure (before heating) with reaction time of 0–3 h. The activity of the catalysts are in the order of NiC > NiP > NiS; however NiC tended to promote cracking reaction resulting in high gasoline and gaseous yields. On the other hand, although NiS gives the lowest oil conversion, it is favorable to diesel yield with lowest methanation and cracking activity. Compared with decarboxylation (DCO<inf>2</inf>) and hydrodeoxygenation (HDO), decarbonylation (DCO) was the major route for deoxygenation of coffee oil for all the catalysts. The ratio of (DCO + DCO<inf>2</inf>) to HDO (as represented by C<inf>n-1</inf>/C<inf>n</inf>) decreased in the order NiS > NiC > NiP. Ketones as intermediate products (ca. 3 wt%) were detected in case of NiP. They could be generated via rearrangement of alcohol and keto-enol tautomerism. Significant amount of aromatics (4 wt%) with some isomerization products (0.9 wt%) can also be observed in NiS catalyzed liquid products while trace amount of these compounds were detected for NiP and NiC catalysts. Physiochemical analysis of the diesel fraction exhibited satisfactory properties. The density and kinematic viscosity were consistent with the specification of commercial bio-hydrogenated diesel, NExBTL. Since main products are straight chain hydrocarbons, high cetane index (>110) could be achieved.