Attapulgite supported Cu-Fe-Co based catalyst combination system for CO hydrogenation to lower alcohols

Attapulgite (ATP) and ATP mixed with SiO₂ microspheres (ATPS) supported Cu-Fe-Co modified Fischer-Tropsch (F-T) catalysts were prepared by impregnation method (IM) and impregnation-solution combustion method (IMSC). The catalysts were characterized by N₂ adsorption-desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), hydrogen temperature-programmed reduction (H₂-TPR) and CO₂-temperature programmed desorption (CO₂-TPD). The catalysts were also applied to lower alcohols synthesis from CO hydrogenation. Results show that the IMSC method is much beneficial for the loading, dispersion and reduction of CuO on the prepared catalyst than IM method, which promots the touch of H₂ and CO with Cu active site. The optimum reaction temperature for lower alcohols synthesis is 280℃ for the catalysts prepared by both methods. Through the optimization of catalyst combination system between ATP and ATPS supported Cu-Fe-Co based catalysts (CFCK/ATP, CFCK/ATPS) and Cu/ZnO/Al₂O₃ catalyst (CZA) for methanol synthesis, the ideal catalyst combination system, CZA‖CFCK/ATPS-IMSC, is obtained for lower alcohols synthesis. For the dual-bed configuration, a lower alcohols selectivity of 39.6% with the fraction of C₂₊ alcohols of 22.7% in oxygenates is achieved at CO conversion of 46.3% via the product conversion coupling effect.