iv
The recovery of lactic acid from its dilute aqueous solutions is a major
problem. The ester of lactic acid, namely, methyl lactate has a wide range of
applications. The esterification of an aqueous solution of lactic acid with methanol is
a reversible reaction. As excess of amount water is present in the reaction mixture,
the conversion is greatly restricted by the chemical reaction equilibrium limitations.
In this study the esterification kinetics of lactic acid with methanol both in
the absence and presence of an ion exchange resin as a heterogeneous acid catalyst was investigated with isothermal batch experiments between 40 - 70 0 C and at
atmospheric pressure. Self-polymerization of lactic acid was enlightened by
considering the hydrolysis reaction of lactoyllactic acid at the reaction temperatures
and at various initial concentrations. Both homogeneous and heterogeneous reaction
rate constants were evaluated.
Methyl lactate process development was also investigated. The process
was based on the recovery of 10% lactic acid by reaction with methanol in a
absorption column using ion-exchange resin Lewatit SPC-112 H+.
The effect of various parameters including lactic acid concentration or
reactant molar ratio, lactic acid feed flow rate, methanol and inert carrier rate on
reactor performance were studied. The reaction of methyl lactate formation over the
ion exchange resin catalyst was observed to be slower than the mass transfer rate
whereas mass transfer of methanol in gas phase was the limiting step for methanol
transfer to the liquid mixture. Mass transfer of water from liquid phase to the gas
phase was controlled by the mass transfer resistance of liquid phase. Thus, it can be
concluded that the counter-current gas-liquid reactors with acidic solid catalysts can
be used as simultaneous reaction and separation equipment.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12605027/index.pdf |
| Date | 01 April 2004 |
| Creators | Akbelen Ozen, Serap |
| Contributors | Karakas, Gurkan |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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