Texture and acidity of amorphous silica-alumina regulated by the complex-decomposition method for steam reforming of dimethyl ether

Abstract

In this work, amorphous silica-alumina composite (ASA) with varied compositions was synthesized via the complex-decomposition method with different complex agents. The XRD characterization revealed the amorphous nature of ASA composites regardless of the synthesis conditions. However, the acidity and the textural properties of ASA composites characterized by BET, Py-FTIR and NH3-TPD were significantly affected by the specific complex agent and amount, Si/Al molar ratio and calcination temperature. Among the investigated complex agents, the optimal amount of ammonium carbonate was the most efficient in tailoring both the textural and acidic properties of ASA. The hybrid of the synthesized ASA and a commercial Cu/ZnO/Al2O3 was studied for the steam reforming of dimethyl ether (SRD), and ASA synthesized by using ammonium carbonate as the complexing agent showed the optimal activity. Importantly, the synergetic effect between ASA and Cu/ZnO/Al2O3 was found to play a crucial role in determining the activity and stability of the bifunctional catalyst, and the partial oxidation of Cu0 to Cu+ induced from the ASA acidity had a great contribution to the deactivation of the bifunctional catalyst. These understandings are favorable for developing a more efficient solid acid for SRD.