Sustainability Assessment of Chemical Processes: Evaluation of Three Synthesis Routes of DMC
Table 6
Facts and assumptions regarding the three reaction routes.
Route A: direct synthesis from carbon dioxide and methanol
Route B: transesterification of methanol and propylene carbonate
Route C: oxidative carbonylation of methanol (ENiChem)
Reaction route (stoichiometric feed [kmol])
CO2 + 2CH3OH (CH3O)2CO + H2O
C3H6O + CO2 C4H6O3 C4H6O3 + 2CH3OH (CH3O)2CO + C3H8O2
2CH3OH + 1/2O2 + CO (CH3O)2CO + H2O
Atom economy [%] (theoretical)
83.3
60.8
83.3
Raw materials
CO2 and CH3OH
CH3OH, CO2, C3H6O3 Intermediate: C4H6O3
CH3OH, O2 and CO
Supply chain
CH3OH from natural gas CO2 separated from flue gas by absorption (MEA)
CH3OH from syngas CO2 separated from flue gas by absorption (MEA) Propylene oxide from H2O2 and propene
CH3OH from natural gas O2 from air (distillation) CO from natural gas
Solvents and auxiliary chemicals
IL101 as a promoter
No solvents or auxiliary chemicals
No solvents or auxiliary chemicals
Catalyst
CHT-HMS
First step: ion exchange resin D201 Second step: IL 103
CuCl2
By-products and coproducts
H2O unreacted CH3OH
Propylene glycol, unreacted CH3OH, and propylene carbonate
H2O, unreacted CH3OH, O2, CO, and H2O
Waste and emissions
Methylformate, unreacted CO2
No wastes
No wastes
Process conditions
Pressure 150 bar Temp. 50°C Supercritical CO2
First step:
Pressure 140 bar Temp. 100°C Supercritical CO2
Pressure 27 bar Temp. 120°C
Second step:
Pressure 1.01325 bar Temp. 150°C
Health and safety issues
Methyl formate (i) is extremely flammable (ii) is harmful if swallowed or inhaled (iii) causes serious eye irritation (iv) may cause respiratory irritation
Propylene oxide (i) is extremely flammable (ii) is harmful if swallowed, inhaled, or came in contact with skin (iii) may cause respiratory irritation (iv) may cause genetic defects and cancer
CO is (i) flammable (ii) toxic for human CO and O2 must be fed at a carefully controlled rate to avoid the risk of explosion
