Extrusion of Cu/ZnO catalysts for the single-stage gas-phase processing of dimethyl maleate to tetrahydrofuran

Bifunctional catalysts consisting of copper, zinc oxide, and γ-alumina have been produced by means of extrusion. The effects of formulation and forming conditions on morphology, pore texture, and copper surface area are discussed. These extruded catalysts have been employed in the fixed-bed gas-phase conversion of dimethyl maleate at temperatures between 453 and 493 K and space velocities ranging from 0.2 to 2.4 h−1. Copper catalyzes the hydrogenation and hydrogenolysis reactions yielding γ-butyrolactone, and 1,4-butanediol. γ-Alumina provides weakly acidic sites which promote the subsequent dehydration of 1,4-butanediol to tetrahydrofuran. Coupled products are methanol and water. Through choice of composition and pore texture of the extrudates it is possible to achieve tetrahydrofuran yields of 100% (basis the C4-products) at a low pressure (2.5 MPa) in a single stage.