(492b) Heat Integrated Reactive and Extractive Distillation for the Synthesis of Carbonates In Emerging Markets

Carbonates
are generally environmentally benign and biodegradable products. In particular,
dimethyl carbonate (DMC) because of its high oxygen content, is an idea
additive for gasoline to replace methyl tert-butyl ether (MTBE). DMC has many
applications in the synthesis of polycarbonates, production of methyl
isocyanate and as a replacement of halogenated solvents.  Carbonates are also
extensively used as a methylating and carbonylating agent. Recently carbonates
have become very important solvents in the emerging markets like lithium ion
battery solutions and other electrochemical and coating sectors.

The
emphasis of this paper is on production of DMC in which its early commercial
production was via phosgenation of methanol. The phosgene route has many draw
backs especially the toxicity of phosgene and is being phased out and replaced
by other methods. Among these new routes of producing DMC are the oxidative
carbonylation of methanol involving CO, transesterification using propylene
carbonate or ethylene carbonate to co-produce DMC and propylene glycol or
ethylene glycol, and methanolysis of urea.  The merits of each of the new
routes of producing DMC will be presented especially the systematic choice of
entrainers in the extractive distillation step to separate the DMC-Methanol
azeotrope common to all the three routes. The main objective of this project is
energy savings which is being explored by using heat integrated reactive and
extractive distillation techniques as will be presented.