**The Design and Simulation of the Synthesis of Dimethyl Carbonate and the Product Separation Process Plant**

Feng Wang1, Ning Zhao1, Fukui Xiao1, Wei Wei1 and Yuhan Sun1,2 *1State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan Shanxi 2Low Carbon Energy Conversion Center, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai P.R. China* 

#### **1. Introduction**

60 Distillation – Advances from Modeling to Applications

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Dimethyl carbonate (DMC) has become a green and environmental benign chemical due to its multiple reactivity and widely potential usage in chemical industry1. It has been used as a substitute to replace dimethyl sulfate and methyl halides in methylation reactions and as a carbonylation agent to substitute phosgene for the production of polycarbonates and urethane polymers. It also has been evaluated to apply as non-aqueous electrolyte component in lithium rechargeable batteries. Additionally, DMC is a strong contender to help the refining industry meet the Clean Air Act specifications for oxygen in gasoline. DMC has about 3 times the oxygen content as methyl tert-butyl ether (MTBE) and its synthesis is not dependent upon FCU isobutylene yields like MTBE. DMC has a good blending octane (R + M/2 = 105), it does not phase separate in a water stream like some alcohols do, and it is both low in toxicity and quickly biodegradable2.

Many of the properties of DMC make it a genuinely green reagent, particularly if compared to conventional alkylating agents, such as methyl halides (CH3X) and dimethyl sulfate (DMS) or to phosgene used as a methoxycarbonylating reagent. Firstly, DMC has been proved to be a nontoxic compound. Some of the toxicological properties of DMC and phosgene and DMS are compared in Table 1. Secondly, it has been classified as a flammable liquid, smells like methanol, and does not have irritating or mutagenic effects either by contact or inhalation. Therefore, it can be handled safely without the special precautions required for the poisonous and mutagenic methyl halides and DMS and the extremely toxic phosgene. Some physicochemical properties of DMC are listed in Table 2.

The phosgene-free route for synthesis of DMC has been widely concerned by academic and industrial researchers, such as the oxidative carbonylation of methanol, the transesterification of propylene or ethylene carbonate (PC or EC), the methanolysis of urea and direct synthesis of carbon dioxide with methanol. Recently, the newly derived route of the synthesis of DMC by urea methanolysis method was considered as a novel routine for the DMC synthesis because of the advantages of easily obtained materials, moderate

The Design and Simulation of the Synthesis of

371.47 130.62 393.55 245.25

Table 3. Experimental vapor pressure and boiling point for DMC

Dimethyl Carbonate and the Product Separation Process Plant 63

T (K) P0(kPa) T (K) P0(kPa) T (K) P0(kPa) 326.06 26.66 372.06 133.29 393.98 247.92 328.41 29.32 372.67 135.96 394.39 250.58 330.58 31.99 373.27 138.62 394.80 253.25 332.61 34.66 373.91 141.29 395.18 255.92 334.53 37.32 374.54 143.95 395.58 258.58 336.34 39.99 375.15 146.62 395.99 261.25 338.03 42.65 375.73 149.28 396.38 263.91 339.64 45.32 376.33 151.95 396.77 266.58 341.20 47.98 376.89 154.62 397.16 269.24 342.68 50.65 377.37 157.28 397.54 271.91 344.09 53.32 377.94 159.95 397.95 274.58 345.45 55.98 378.47 162.61 398.29 277.24 346.75 58.65 379.02 165.28 398.67 279.91 348.04 61.31 379.63 167.94 398.93 282.57 349.26 63.98 380.05 170.61 399.30 285.24 350.43 66.64 380.62 173.28 399.66 287.91 351.57 69.31 381.16 175.94 400.02 290.57 352.69 71.98 381.71 178.61 400.38 293.24 353.77 74.64 382.23 181.27 400.66 295.90 354.81 77.31 382.71 183.94 400.99 298.57 355.86 79.97 383.22 186.61 401.35 301.23 356.85 82.64 383.73 189.27 401.66 303.90 357.81 85.31 384.40 191.94 402.03 306.57 358.72 87.97 384.98 194.60 402.39 309.23 359.63 90.64 385.48 197.27 402.76 311.90 360.54 93.30 385.95 199.93 403.11 314.56 361.73 95.97 386.45 202.60 403.46 317.23 362.14 97.30 386.92 205.27 403.80 319.89 362.55 98.63 387.40 207.93 404.50 325.23 362.98 99.97 387.91 210.60 405.15 330.56 363.46 101.30 388.33 213.26 405.45 333.22 363.84 102.63 388.77 215.93 406.12 338.56 364.24 103.97 389.25 218.59 406.75 343.89 364.65 105.30 389.70 221.26 407.03 346.55 365.04 106.63 390.14 223.93 407.69 351.88 365.63 109.30 390.59 226.59 408.31 357.22 366.37 111.96 391.04 229.26 408.56 359.88 367.10 114.63 391.45 231.92 409.22 365.21 367.89 117.29 391.89 234.59 409.82 370.54 368.65 119.96 391.89 234.59 410.13 373.21 369.38 122.63 392.31 237.26 410.71 378.54 370.10 125.29 392.75 239.92 411.09 381.21 370.80 127.96 393.15 242.59 411.29 383.87


a NOEC=Concentration which does not produce any effect.

Table 1. Comparison between the Toxicological and Ecotoxicological Properties of DMC, Phosgene, and DMS1


Table 2. Some Physical and Thermodynamic Properties of DMC1

reaction conditions and low investment for equipment. As a result, the separation of the reacted mixture which contain an azeotropic mixture of DMC and methanol became very important for the production of DMC.
