Our version of the process consists of four stages. In the first stage, butadiene, carbon monoxide, and methanol are reacted in the presence of a carbonylation catalyst consisting of a palladium salt and a bidentate phosphorus ligand. The reaction is carried out in the liquid phase with diphenyl ether as the solvent. The product, consisting of methylformylvalerate isomers, is separated from the unreacted methyl 4-pentenoate, with the latter recycled to the hydroformylation stage. The products, along with a recirculating xylene stream, are then sent to a multitublar reactor where they are converted to caprolactam and methanol.
Methanol is recycled for reuse.
The process has the potential to produce caprolactam at a somewhat lower cost than existing commercial routes. All rights reserved .