Unveiling the effects of support crystal phase on Cu/Al2O3 catalysts for furfural selective hydrogenation to furfuryl alcohol

Support crystal phase plays a crucial role in the controlled C--O hydrogenation over the supported catalysts. Herein, the effects of Al2O3 crystal phase (alpha, 0, i, and gamma) on the supported Cu-based catalyst is highlighted for furfural (FAL) hydrogenation to furfuryl alcohol (FA). The evaluation results show that Cu/i-Al2O3 exhibits the best performance (FAL conversion: 99.7 %, FA selectivity: 94.0 %), highest TOF value (29.3 h(- 1)) and lowest apparent activation energy (66.3 kJ/mol). The comprehensive characterizations unravel that Cu/i-Al2O3 has the smallest Cu nanoparticles and the highest content of Cu+ and Cu-0, which facilitates H-2 dissociation and FAL adsorption. The reaction mechanisms suggest that Cu/i-Al2O3 has the strongest FAL adsorption and FA desorption capacity. Moreover, it is demonstrated that FAL is linear chemical adsorption on the catalyst surface in the eta(1)(O) configuration, which avoids the furan ring hydrogenation, and thereby, results in the high FA selectivity. This work would provide some references for developing the high-efficiency C--O hydrogenation catalysts.