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Intensification of reactive distillation for TAME synthesis based on the analysis of multiple steady-state conditions
(2018-12-01)
Yamaki, Takehiro
;
Matsuda, Keigo
;
Na-Ranong, Duangkamol
;
Matsumoto, Hideyuki
Our previous study reported that operation in multiple steady states contributes to an improvement in reaction conversion, making it possible to reduce the energy consumption of the reactive distillation process for tert-amyl methyl ether (TAME) synthesis. This study clarified the factors responsible for an improvement in the reaction conversion for operation in the multiple steady states of the reactive distillation column used in TAME synthesis. The column profiles for those conditions, in which multiple steady states existed and those in which they did not exist, were compared. The vapor and liquid flow rates with the multiple steady states were larger than those when the multiple steady states did not exist. The effect of the duty of the intermediate condenser, which was introduced at the top of the reactive section, on the liquid flow rate for a reflux ratio of 1 was examined. The amount of TAME production increased from 55.2 to 72.1 kmol/h when the intermediate condenser was operated at 0 to -5 MW. Furthermore, the effect of the intermediate reboiler duty on the reaction performance was evaluated. The results revealed that the liquid and vapor flow rates influenced the reaction and separation performances, respectively.
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Kinetics, isotherm and thermodynamics of sterol adsorption on styrene-divinylbenzene anion-exchange resins
(2018-10-01)
Ladadok, Chinakrit
;
Yamaki, Takehiro
;
Matsuda, Keigo
;
Matsumoto, Hideyuki
;
Na-Ranong, Duangkamol
Phytosterols can be recovered from natural resources using molecular distillation, cold crystallization, which require large energy consumption. Adsorption was considered as a feasible alternative method. In this study, kinetics, isotherm and thermodynamics of stigmasterol adsorption on styrene-divinylbenzene with two different functional groups, strong base (SB-R) and weak base (WB-R), were investigated using a model solution of stigmasterol in n-heptane. Isothermal adsorption experiments were performed in temperature range of 298-313 K and concentration range of 0.3-6.0 mg/g<inf>sol</inf>. For both SB-R and WB-R cases, kinetics of adsorption was analysed based on pseudofirst- order and pseudo-second-order models and the results revealed that pseudo-second-order model agreed with the experimental data much better than pseudo-first-order model. Analysis of isotherm data based on Langmuir, Freundlich and linear models showed that Freundlich was the best model that could predict behaviour of sterol adsorption for both SB-R and WB-R cases. In addition, thermodynamics parameters (δG, δH andδS) indicated that the sterol adsorptions on these adsorbents were spontaneous, exothermic and favourable at low temperature.
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Energy-saving performance of reactive distillation process for TAME synthesis through multiple steady state conditions
(2018-08-01)
Yamaki, Takehiro
;
Matsuda, Keigo
;
Na-Ranong, Duangkamol
;
Matsumoto, Hideyuki
We have previously reported the existence of steady-state solutions where reaction conversion is improved within multiple steady states, which appear in the reactive distillation column for tert-amyl methyl ether (TAME) synthesis. In the present study, we examined the energy-saving performance of a reactive distillation process that comprises a reactive distillation column and two recovery distillation columns for multiple steady state conditions using steady-state process simulation. Bifurcation analysis revealed that the multiple steady state did not exist under a reflux ratio of 1, but existed under reflux ratios of 2, 3, and 4. The reboiler duty required to obtain high-purity TAME increased with increase in reflux ratio. The evaluation of energy consumption revealed that the reboiler duties of the second recovery column at the steady-state solutions in the multiple steady state were lower than that at the steady-state solution of reflux ratio 1. Due to the high reaction conversion and reduction of the reboiler duty in the second recovery column, the energy inputs per mole of TAME product at steady-state solutions of the multiple steady state with reflux ratios of 2, 3, and 4 reduced by 17, 12, and 6%, respectively, compared to that for reflux ratio 1.
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Kinetics, isotherm, and thermodynamics of adsorption of sterol on strong acid ion exchange resin
(2018-01-01)
Ladadok, Chinakrit
;
Yamaki, Takehiro
;
Matsuda, Keigo
;
Matsumoto, Hideyuki
;
Na-Ranong, Duangkamol
Kinetics, isotherm and thermodynamics of sterol adsorption on styrene-divinylbenzene based ion-exchange resin with strong acid was investigated at temperature in the range of 298 to 313 K using a model solution of stigmasterol in n-heptane with initial concentration in the range of 0.3×10-3 to 1.8×10-3 kg/kg-solution. Adsorbent (5 wt%) was added to the model solution and isothermal adsorption was performed at 3.33 rps for 7.2×103 s. Kinetics of sterol adsorption was analysed based on pseudo-first-order and pseudo-second-order models. The results revealed that pseudo-second-order model agreed with the experimental data, much better than pseudofirst- order model. At the equilibrium of adsorption, adsorption capacity (qe) decreased when the temperature was increased. This result indicated that sterol adsorption was exothermic. Analysis of adsorption isotherm data based on Langmuir, Freundlich and linear models showed that Freundlich was the best model that could predict the adsorption isotherm data. Adsorption equilibrium constants calculated based on Freundlich model at various temperatures were used to calculate Gibb's free energy change (ΔG), enthalpy change (ΔH), and entropy change (ΔS). The increase of ΔG with respect to temperature indicated that the adsorption was more favourable at lower temperatures. The negative value of ΔH indicated that the adsorption was exothermic and agreed well with the effect of temperature on adsorption capacity. The negative value of ΔS indicated associative adsorption and decrease of the randomness between the solid/liquid interfaces due to the adsorption.
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Energy saving characteristics of an internal heat integrated reactive distillation process for methyl acetate synthesis
(2016-03-20)
Yamaki, Takehiro
;
Matsuda, Keigo
;
Na-Ranong, Duangkamol
;
Matsumoto, Hideyuki
A model for an internally heat integrated reactive distillation process without a compressor was developed, and the synthesis of methyl acetate from methanol and acetic acid was simulated. The applicability was evaluated by using the process simulator Aspen Plus. The steady state simulation showed that the energy consumption of the heat integrated reactive distillation process was lower than that of conventional reactive distillation.

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