**6. Separation of the mixture of methanol and DMC**

Separation of azeotropic mixtures is a challenge commonly encountered in commodity and fine chemical processes. Many techniques suitable for separation of azeotropic mixtures have been developed recently, such as pressure-swing distillation (PSD), extractive and azeotropic distillation, liquid-liquid extraction, adsorption, prevaporation using membrane, crystallization and some new coupling separation techniques. Despite of the newly developed membrane separation process or adsorption process, it was very important to properly design of the traditional separation of DMC from the reaction mixture using the distillation tower with the existence of the azeotrope of methanol-DMC for large scale of DMC production.

Zhang18 has developed a process model for atmospheric-pressurized rectification to simulate the separation of DMC and methanol with low concentration DMC, which came from the DMC synthesis through urea methanolysis method. The simulation was carried out based on the Aspen Plus platform with the Wilson liquid activity coefficient model.

Li4 has given a pressurized-atmospheric separation process for separating the product of DMC from the mixture of methanol and DMC with 30 wt.% of DMC based on the simulation model. They have optimized the operating conditions based on the developed process and the optimized condition: 40 of ideal stages, 29th of feed stage, 7~10 of reflux ratio and 1.3 MPa of pressure for pressurized distillation. However, this process has a drawback of high investment of the equipment and lower stability of operation. Our

The Design and Simulation of the Synthesis of

Equilibria 198 (2002) 95–109.

Eng. Sci. 2001, 56, 387.

1993.

Chem Res,2007,46(26):8972–8979.

ENGINEERING(CHINA), 2009, 37(2): 71-74

TECHNOLOGY, 2007, 36(11): 1128-1133

**7. References** 

706.

35, 15.

Dimethyl Carbonate and the Product Separation Process Plant 89

[1] Tundo, P.; Selva, M. The Chemistry of Dimethyl Carbonate. Acc. Chem. Res. 2002, 35,

[2] Ono, Y. Dimethyl Carbonate for Environmentally Benign Reactions. Catal. Today 1997,

[3] Rodriguez, J. Canosa, A. Dominguez, J. Tojo. Isobaric vapour–liquid equilibria of

[4] Rodriguez, J. Canosa, A. Dominguez, J. Tojo. Vapour–liquid equilibria of dimethyl

[6] Wang-Ming Hu, Lv-Ming Shen, Lu-Jun Zhao. Measurement of vapor–liquid equilibrium

[7] Agreda, V. H.; Partin, P. H.; Heise, W. H. High Purity Methyl Acetate via Reactive

[8] Pilavachi, P. A.; Schenk, M.; Perez-Cisneros, E.; Gani, R. Modeling and Simulation of Reactive Distillation Operations. Ind. Eng. Chem. Res. 1997, 36, 3188. [9] Malone, M. F.; Doherty, M. F. Reactive Distillation. Ind. Eng. Chem. Res. 2000, 39, 3953. [10] Tuchlenski, A.; Beckmann, A.; Reusch, D.; DuKssel, R.; Weidlich, U.; Janowsky, R.

[11] Xu, Y.; Zheng, Y.; Ng, F. T. T.; Rempel, G. L. A Three-phase Nonequilibrium Dynamic

[12] Wang Feng, Zhao Ning, Li Junping, et al. Modeling of the Catalytic Distillation Process

[13] Taylor, R.; Krishna, R. Multicomponent Mass Transfer; John Wiley and Sons: New York,

[14] Wang Feng, Zhao Ning, LI Jun-ping, Xiao Fu-kui, Wei Wei, Sun Yu-han. Modeling

[15] Wang Feng, Zhao Ning, Li Junping, Xiao Fukui, Wei Wei, Sun Yuhan. Simulation of

[16] Wang Feng, Zhao Ning, Li Junping, et al. Non-Equilibrium Model for Catalytic

[17] Wang Feng, Zhao Ning, Li Junping, Wu Dudu, Wei Wei, Sun Yuhan. Non-Equilibrium

Distillation Process[J].Rront Chem Eng Chin,2008, 2(4): 379-384.

Model for Catalytic Distillation. Chem. Eng. Sci. 2005, 60, 5637.

UNIFAC and ASOG method. Fluid Phase Equilibria 201 (2002) 187–201 [5] Ding Wang, Aiguo Xuan, Yuanxin Wua, Zhiguo Yana, Qimei Miao. Study on gas–

carbonate. Fluid Phase Equilibria, 302 (2011) 269–273

kPa. Fluid Phase Equilibria, 219 (2004) 265–268

Distillation. Chem. Eng. Process. 1990, 86, 40.

dimethyl carbonate with alkanes and cyclohexane at 101.3 kPa. Fluid Phase

carbonate with linear alcohols and estimation of interaction parameters for the

liquid equilibria with the UNIFAC model for the systems of synthesizing dimethyl

for binary mixtures of phenol–dimethyl carbonate and phenol–methanol at 101.3

Reactive Distillation - Industrial Applications, Process Design & Scale-up. Chem.

for the Synthesis of Dimethyl Carbonate by Urea Met hanolysis Method[J]. Ind Eng

analysis for process operation of synthesis of Dimethyl carbonate. CHEMICAL

Catalyst distillation Using Non-Equilibrium model. PETROCHEMICAL

Stage Model for Dimethyl Carbonate Synthesis by Urea Methanolysis in Catalytic Distillation Tower. PETROCHEMICAL TECHNOLOGY, 2008, 37(4): 359-363

Fig. 6. The schematic diagram of the pressure swing process.

workers, Zhang et al., also developed a novel separation process of atmospheric-pressurized separation process which had the ability to separate the low concentration of DMC for the separation of the mixture with 12 wt.% of DMC base on the 500t/a pilot plant by the simulation model. The sensitive study and the optimization to this process had shown that the reflux ratio for the atmospheric and pressurized distillation had been 3.4 and 1.0 respectively, and 0.65, 0.93 of the distillate to feed ratio for the atmospheric and pressurized distillation. In this process, 99.5wt.% or higher concentration of methanol could be recovered, while the pressurized-atmospheric separation process could only obtained a solution containing 13.3 wt.% of DMC in the recovered methanol stream.

The model simulation and process design for the separation of DMC and methanol has been lettered in many literatures. Much number of the literatures had been presented on the simulation for the DMC synthesis with trans-esterification method, in addition with the detailed research on the catalytic distillation for the DMC synthesis by urea and methanol. However, the simulation work for the other DMC synthesis process had been little reported. Furthermore, the pressure-swing distillation process, the extractive distillation process and the azeotropic distillation process had been developed in the open reported simulative literatures for the product separation of DMC and methanol mixture. Among the derived separation process, the pressure swing distillation process and the extractive distillation process had been considered suitable for the product separation of DMC and methanol mixture.
