Hydrothermal stability of gamma-Al2O3 supports varied with crystal plane orientation of pseudo-boehmite precursor

Abstract

Porous spherical γ-alumina supports play the key role in the petroleum reforming industry with strict requirement in hydrothermal stability of pore structure. Here, a series of pseudo-boehmite samples with different crystal orientations were synthesized in a separate nucleation and aging steps method by adjusting the rotating speed. The pseudo-boehmite (PB-1000) at 1000 rpm yields a high (020) plane proportion of 44.52 %, which is comparable with that of 43.91 % for the Sasol Boehmite (SB) powder. The Al2O3-1000 from the PB-1000 demonstrated the highest content of γ-Al2O3 phase, the lowest surface hydroxyl number of 1.56/nm2, and the highest hydrothermal stability with the retention rate of 75.0 % (174 m2·g−1) at 600 °C under water vapor for 120 h, which is comparable to that of 72.3 % (191 m2·g−1) for the Sasol sample. It is the first time to investigate hydrothermal stability of alumina from the content of γ-Al2O3 phase and the surface hydroxyl groups.