Towards a low temperature, liquid phase methyl methacrylate process through mechanism-guided process design

Beaumont, Michael (2015) Towards a low temperature, liquid phase methyl methacrylate process through mechanism-guided process design. PhD thesis, University of Liverpool.

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Abstract

A liquid (slurry) phase, base-catalysed process for the production of methyl methacrylate from methyl propanoate and formaldehyde has been developed, that runs at temperatures around 200 °C below the current, heterogeneous process (160-180 °C vs. 330-360 °C) running at ALPHA-1, a commercial, methyl methacrylate-producing chemical plant. Initially, caesium carbonate was used as the base, however fast deactivation of this base, producing hydroxide, results in the formation of inactive bases, caesium propanoate and caesium methacrylate from methyl esters. Through understanding of the mechanism of base deactivation, a new base catalyst, caesium methylcarbonate, was developed that does not act as a source of hydroxide. Understanding of the mechanisms of the condensation reaction, base deactivation and formaldehyde decomposition has allowed a system to be developed that achieves high conversions of methyl propanoate with excellent selectivity (up to 43 % conversion with up to 99.5 % selectivity on methyl propanoate, compared with 18 % conversion at 93 % selectivity in the current process). The system requires a polar, aprotic solvent to increase the activity of the base catalyst and high temperature addition is essential for high selectivity on formaldehyde. The caesium methylcarbonate is slowly deactivated through reaction of methyl esters with water, the co-product of the condensation reaction, to caesium propanoate and caesium methacrylate. For this reason, systems for the recycling to these methyl esters and caesium methylcarbonate have been developed so that multiple turnovers on caesium can be achieved through reaction-regeneration cycles. Regeneration of the active base can be achieved in a separate process step using carbon dioxide and methanol, to effectively reverse the equilibrium by which hydrolysis occurs, or with an in situ method using dimethyl carbonate as a sacrificial scavenger. A patent has been submitted to cover the work in this thesis and work on this project is continuing at Lucite International, the sponsors of this PhD studentship. This process is under active consideration for scale up and commercialization.

Item Type:	Thesis (PhD)
Additional Information:	Date: 2015-09-20 (completed)
Subjects:	?? QD ??
Divisions:	Faculty of Science and Engineering > School of Physical Sciences > Chemistry
Depositing User:	Symplectic Admin
Date Deposited:	01 Sep 2016 13:40
Last Modified:	17 Dec 2022 02:10
DOI:	10.17638/02037982
URI:	https://livrepository.liverpool.ac.uk/id/eprint/2037982