Toluene Diisocyanate from Toluene Diamine by Bayer Gas Phase Phosgenation Preliminary Evaluation

Published December 2008

The recent developments announced by Bayer MaterialScience concerning technology to make toluene diisocyanate by gas-phase phosgenation seem to offer new technology to a fairly mature industry. Announcements of scale, performance, energy savings and actions to build a new facility in China imply that there is something to the new technology. The patent literature is somewhat sparse on the subject and few details are published, so there are a lot of questions to be answered before an analysis of the potential design can be completed. Initial attempts wandered down several erroneous paths because of the lack of hard data and definitive route information. The limited information has raised questions about the scale of the project, and whether it is a single line or parallel lines. Since comments seem to suggest that the scale is a single process line, this analysis attempted to build a design based on the maximum scale announced.

The effort managed to compile a plausible design as a single process line to the 300 kmt/yr scale. Limitations in costing correlation functions limit that design though by forcing parallel equipment and disallowing extrapolation beyond the limit of the correlations. However, extrapolation of refrigeration costs introduced an anomaly to the analysis too. Therefore, this analysis is limited to a preliminary assessment that shows promise, but will require more data and analysis to improve the result.