Structure–activity relationships of Co-modified Cu/ZnO/Al 2 O 3 catalysts applied in the synthesis of higher alcohols from synthesis gas

•Characterization of active Co-modified Cu/ZnO/Al2O3 catalyst after 40h time on stream.•Product distribution shifted towards higher alcohols during initial deactivation.•Best trade-off between activity and selectivity for Cu/Co=2.5.•Surface composition strongly affected by the conditions during activation and HAS.•Surface alloying of large Cu0 particles and metallic Co surface sites detected.