Catalyst Development Efforts during Scale-up of the THF ex-Butane Process

In the 1990's, DuPont embarked on an program to renew the Lycra® supply chain.  Part of this effort was to develop a lower-cost process for tetrahydrofuran (THF).  A 2-step process based on butane was selected for scale-up.  It was believed this process could provide lower cost THF than the existing Reppe process which is based on natural gas through formaldehyde and acetylene.   In step 1 of the butane-based process, butane was partially oxidized to maleic anhydride in a circulating fluidized bed reactor using attrition resistant vanadium phosphorus oxide (VPO) catalyst.  In step 2, the maleic anhydride was hydrolyzed to maleic acid and then hydrogenated to THF on a supported precious-metal catalyst.   The overall process and the catalyst manufacturing for each process step were scaled up from lab to pilot to commercial scale.  This poster will focus on selected challenges and successes around scale-up and performance of the catalyst.