Suttichai Assabumrungrat

Production of bio-hydrogenated diesel by catalytic hydrotreating of palm oil over NiMoS2/γ-Al2O3 catalyst.

Catalytic hydrotreating of palm oil (refined palm olein type) to produce bio-hydrogenated diesel (BHD) was carried out in a continuous-flow fixed-bed reactor over NiMoS2/γ-Al2O3 catalyst. Effects of dominant hydrotreating parameters: temperature: 270-420°C; H2 pressure: 15-80 bar; LHSV: 0.25-5.0 h(-1); and H2/oil ratio: 250-2000 N(cm(3)/cm(3)) on the conversion, product yield, and a contribution of hydrodeoxygenation (HDO) and decarbonylation/decarboxylation (DCO/DCO2) were investigated to find the optimal hydrotreating conditions. All calculations including product yield and the contribution of HDO and DCO/DCO2 were extremely estimated based on mole balance corresponding to the fatty acid composition in feed to fully understand deoxygenation behaviors at different conditions. These analyses demonstrated that HDO, DCO, and DCO2 reactions competitively occurred at each condition, and had different optimal and limiting conditions. The differences in the hydrotreating reactions, liquid product compositions, and gas product composition were also discussed.

Synthesis of methyl esters from relevant palm products in near-critical methanol with modified-zirconia catalysts

The transesterification and esterification of palm products i.e. crude palm oil (CPO), refined palm oil (RPO) and palm fatty acid distillate (PFAD) under near-critical methanol in the presence of synthesized SO(4)-ZrO(2), WO(3)-ZrO(2) and TiO(2)-ZrO(2) (with various sulfur- and tungsten loadings, Ti/Zr ratios, and calcination temperatures) were studied. Among them, the reaction of RPO with 20%WO(3)-ZrO(2) (calcined at 800 degrees C) enhanced the highest fatty acid methyl ester (FAME) yield with greatest stability after several reaction cycles; furthermore, it required shorter time, lower temperature and less amount of methanol compared to the reactions without catalyst. These benefits were related to the high acid-site density and tetragonal phase formation of synthesized WO(3)-ZrO(2). For further improvement, the addition of toluene as co-solvent considerably reduced the requirement of methanol to maximize FAME yield, while the addition of molecular sieve along with catalyst significantly increased FAME yield from PFAD and CPO due to the inhibition of hydrolysis reaction.

Thermodynamic Analysis for Gasification of Thailand Rice Husk with Air, Steam, and Mixed Air/Steam for Hydrogen-Rich Gas Production

Thermodynamic analysis of gasification with air, steam, and mixed air-steam was performed over rice husk to determine the optimum conditions (i.e., equivalence ratio (ER), steam to biomass ratio (SBR) and operating temperature) that can maximize the yield of hydrogen production with low energy consumption. It was found that for air gasification, H2 production is always less than CO production and considerably decreased with increasing ER. For steam gasification, the simulation revealed that H2 production is greater than CO, particularly at high SBR and low temperature; furthermore, H2 yield increased steadily with increasing temperature and SBR until reaching SBR of 3.5-4.0, then the effect of steam on H2 yield becomes less pronounced. As for the mixed steam/air gasification, H2 production yield increased with increasing SBR, but decreased dramatically with increasing ER (up to 0.4). Among these three operations, the highest H2 production yield can be achieved from the steam gasification with SBR of 4.0. Nevertheless, by considering the system efficiency, the combined air-steam gasification provided significant higher hydrogen production efficiency than the other two operations. The optimum condition for combined air-steam gasification can be achieved at 900°C with ER of 0.1 and SBR of 2.5, which provided the efficiency up to 66.5 percent.

Theoretical study on the synthesis of methyl acetate from methanol and acetic acid in pervaporation membrane reactors: effect of continuous-flow modes

Abstract The synthesis of methyl acetate (MeOAc) from methanol (MeOH) and acetic acid (HOAc) in pervaporation membrane reactors (PVMRs) is discussed in this paper. Three modes of PVMR operation, i.e. semi-batch (SB-PVMR), plug-flow (PF-PVMR) and continuous stirred tank (CS-PVMR) were modeled using the kinetic parameters of the reaction over Amberlyst-15 and permeation parameters for a polyvinyl alcohol (PVA membrane). Both of the reaction and permeation rates are expressed in terms of activities. The PVA membrane shows high separation factors for HOAc and MeOAc but very low for MeOH. The simulation results of SB-PVMR mode show quite good agreement with the experimental results. The study focused on comparing PVMR performances between two modes of continuous-flow operation for various dimensionless parameters, such as Damkohler number ( Da ), the rate ratio ( δ ), the feed composition and the membrane selectivity. Flow characteristic within the reactors arisen from different operation modes affects the reactor performance through its influences on the reaction and permeation rates along the reactor. There are only some ranges of operating conditions where CS-PVMR is superior to PF-PVMR.

Biodiesel production from palm oil using combined mechanical stirred and ultrasonic reactor.

This paper investigates the production of biodiesel from palm oil using a combined mechanical stirred and ultrasonic reactor (MS-US). The incorporation of mechanical stirring into the ultrasonic reactor explored the further improvement the transesterification of palm oil. Initial reaction rate values were 54.1, 142.9 and 164.2 mmol/L min for the mechanical-stirred (MS), ultrasonic (US) and MS-US reactors, respectively. Suitable methanol to oil molar ratio and the catalyst loading values were found to be 6 and 1 of oil, respectively. The effect of ultrasonic operating parameters; i.e. frequency, location, and number of transducer, has been investigated. Based on the conversion yield at the reactor outlet after 1 h, the number of transducers showed a relevant role in the reaction rate. Frequency and transducer location would appear to have no significant effect. The properties of the obtained biodiesel (density, viscosity, pour point, and flash point) satisfy the ASTM standard. The combined MS-US reactors improved the reaction rate affording the methyl esters in higher yield.

Simulation of pervaporation membrane reactors for liquid phase synthesis of ethyl tert-butyl ether from tert-butyl alcohol and ethanol

Abstract The synthesis of ethyl tert -butyl ether (ETBE) from a liquid phase reaction between ethanol (EtOH) ethyl and tert -butyl alcohol (TBA) in pervaporation membrane reactors (PVMRs) is discussed in this paper. Three modes of PVMR operation; semi-batch reactor (SBR), continuous stirred tank reactor (CSTR) and plug flow reactor (PFR) were modeled using kinetic parameters of the synthesis over β-zeolite and permeability data for a polyvinyl alcohol (PVA) membrane from our previous work. Good agreement between experimental and simulation results for the SBR mode was obtained. The study focused on comparing PVMR performances between two modes of continuous flow operation for various operating parameters, i.e. ratio of catalyst weight to total molar feed rate ( φ ), ratio of membrane area to catalyst weight ( δ ), operating temperature and feed composition. It was found that the CSTR mode shows superior performance to the PFR mode only within some ranges of operating conditions. To obtain high ETBE yields, it is best to operate the PVMRs at low temperature with a high ratio of membrane area to catalyst weight ( δ ) and with the feed ratio of EtOH and TBA at the stoichiometric value or slightly higher.

Catalytic behaviors of Ni/γ-Al2O3 and Co/γ-Al2O3 during the hydrodeoxygenation of palm oil

The deactivation and regeneration behaviors of Ni/γ-Al2O3 and Co/γ-Al2O3 catalysts in the hydrodeoxygenation (HDO) of palm oil were investigated at 573 K and 5 MPa in a trickle bed reactor. The catalysts were prereduced at 773 K for 3 h before the HDO experiments. The catalysts exhibited good catalytic activity (>90% yield) and remained stable for 100 h on-stream. Nevertheless, after 150 h on-stream, the product yield gradually decreased from 92.2 to 76.2% over the Ni catalyst and dramatically declined from 88.6% to ca. 56.6% over the Co catalyst. The combined decarbonylation and/or decarboxylation (DCOx) reactions were dominant over the HDO reaction when the reaction was catalyzed by the Ni catalyst. Meanwhile, the contribution of DCOx and HDO reactions was nearly comparable over the Co catalyst. The XRD and XANES analyses confirmed the partial formation of metallic nickel or cobalt after prereduction and the further in situ reduction during the HDO experiments, suggesting the coexistence of the metal and metal oxides on the catalyst surfaces. The XRD and TEM analyses revealed some sintering of the nickel and cobalt particles during the time course of reaction. Based on the TPO analysis, the carbon deposition rate on the cobalt catalyst was faster than that on the nickel catalyst and would be the major reason for the catalyst deactivation, and the sintering was the minor one. Additionally, the regeneration under air at 773 K followed by reduction in H2 at 773 K can completely restore the catalytic activity.

Production of ethyltert-butyl ether fromtert-butyl alcohol and ethanol catalyzed byβ-zeolite in reactive distillation

The synthesis of ethyl tert-butyl ether (ETBE) from a liquid phase reaction between tert-butyl alcohol (TBA) and ethanol (EtOH) in reactive distillation has been studied.β-Zeolite catalysts with three compositions (Si/Al ratio=13, 36 and 55) were compared by testing the reaction in a semi-batch reactor. Although they showed almost the same performance, the one with Si/Al ratio of 55 was selected for the kinetic and reactive distillation studies because it is commercially available and present in a ready-to-use form. The kinetic parameters of the reaction determined by fitting parameters with the experimental results at temperature in the range of 343–363 K were used in an ASPEN PLUS simulator. Experimental results of the reactive distillation at a standard condition were used to validate a rigorous reactive distillation model of the ASPEN PLUS used in a simulation study. The effects of various operating parameters such as condenser temperature, feed molar flow rate, reflux ratio, heat duty and mole ratio of H2O : EtOH on the reactive distillation performance were then investigated via simulation using the ASPEN PLUS program. The results were compared between two reactive distillation columns: one packed withβ-zeolite and the other with conventional Amberlyst-15. It was found that the effect of various operating parameters for both types of catalysts follows the same trend; however, the column packed withΒ-zeolite outperforms that with Amberlyst-15 catalyst due to the higher selectivity of the catalyst.

Selective oxidation of methane in an SOFC-type reactor: effect of applied potential

The effect of applied potential on the selective oxidation of methane in a solid oxide fuel cell (SOFC)-type reactor was investigated. A tube-type YSZ was used as an electrolyte where a La 1.8 Al 0.2 O 3 anode and a conventional La 0.85 Sr 0.15 MnO 3 cathode were deposited on the inner and outer surfaces of the tube, respectively. The fuel cell-type temperature-programmed desorption (FC-TPD) measurements revealed that the amount of adsorbed oxygen on the anode catalyst was altered with the applied potential. Increasing the applied potential increased the amount of weakly adsorbed oxygen at the oxygenate site. Two operating modes of the SOFC-type reactor were carried out. In the normal mode, it was found that the rate of C 2 formation was not affected by an applied potential. The positive potential increased the rate of carbon oxides formation, especially the product CO, while the negative potential suppressed the rates of CO and CO 2 formation. For the mixed-flow mode, even though the electrochemically promoted rates did not show significant improvement over the open-circuit rates, the catalytic activities of the anode catalyst to different products were altered by the applied potential with non-Faradaic manner. The change in the selectivity of the active site gave a new aspect to non-Faradaic electrochemical modification of catalytic activity (NEMCA) phenomena.

Extractive reaction for epoxidation of cyclohexene to cyclohexene oxide using dioxirane in ketone/Oxone® system

Abstract Extractive reaction for the epoxidation of cyclohexene to cyclohexene oxide using dioxirane was studied. The studies were divided into two main parts: (1) comparison of different cyclohexene oxide preparation methods and (2) effects of operating parameters such as stirring rate, type of solvent, initial solvent/aqueous ratio, temperature, pH and amount of catalyst on the performance of the extractive reaction. The results revealed that the best method was the epoxidation of cyclohexene by dioxirane in an extractive reaction system with presence of a phase transfer catalyst. A maximum conversion obtained from the system without a solvent can be exceeded with an extractive reaction process by introducing of an immiscible solvent to the system. It was found that the cyclohexene oxide yield increased with increasing stirring rate and the amount of acetone, and that the reaction system using dichloromethane showed the highest performance compared to those with toluene and benzene.