Development of a commercial process to produce 1,4-butanediol and tetrahydrofuran

• Main Author: Wood, Michael Anthony
• Published: Durham University 2009
• Subjects: 547
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.549943

This thesis details the experimental programme and research into the formation of 1,4-butanediol and tetrahydrofuran from a novel feedstock dialkylmaleate. This encompassed the evaluation of a range of heterogeneous copper-based catalysts (containing chromium) and subsequent selection and optimisation of one of these catalysts for extended life time studies and eventual use in a commercial facility. The selected operating conditions (temperature of 190 - 205 ºC, pressure 885 psi[g]) ensured that the reaction was performed in the vapour-phase at moderate temperature and pressure to maximise the yield of the main product 1,4- BDO (>95%) and THF (<5%). The thesis details the development of several variants of non-chromium containing Cu-based catalysts, which then enabled a multi-variable product process to be realised. The selection of operating conditions further enhanced the flexibility of the process by operating at temperatures in the 205 - 220 ºC range to increase the selectivity to THF (50 - 95%) responding to changing market conditions. The development of both process options encompasses initial testing, screening and ultimately optimisation of the catalysts using laboratory-based reactors generating data that was suitable for commercial design. The catalysts generated were shown to produce 1,4-BDO and THF over extended periods from the preferred feedstock; dialkylmaleate. The thesis also outlines the importance of the pre-treatment of the catalyst for use in a vapour-phase hydrogenolysis process and that this is a key consideration in achieving any commercially viable process. The operation of the carefully pre-treated catalyst in the vapour-phase enabled a highly efficient process to be developed in the laboratory environment generating design data for commercial facilities, in which all of the development steps were later confirmed in commercial operations in several countries. The development of a solid acid catalyst, used to catalyse the conversion of an acid to ester, is detailed. The ion-exchange resin used as the catalyst was optimised to minimise the main by-products by structuring acid sites on the surface of the solid support only. This enabled high conversions of the acid >99 wt% to be achieved at low temperatures in the region of 95 - 120 ºC, which was an extremely efficient process. The subsequent design and development of a unique reactor for the esterification of the acid species is also outlined in this thesis. The reactor, which is based on a counter-current reactive distillation concept, enabled maximum utilisation of the solid acid catalyst developed and is also reported. This aspect of the thesis involved not only studying the chemical transformation but also a detailed study of the fluid dynamics that would be present in the commercial reactor; this encompassed the build and operation of several cold flow models evaluating not only gas distribution but liquid/resin movement in the reactor. The combination of the two transformations gave a world leading technology to convert maleic anhydride to 1,4-BDO and THF. The work reported in this thesis Is the basis on which further testwork, in both the hydrogenation and esterification, is performed. These process improvements are being researched to ensure the technology remains one of the main manufacturing routes to produce 1,4-BDO and THF from a diaikylmaleate feedstock.