Effect of CaO addition on acid properties of Ni–Ca/Al2O3 catalysts applied to ethanol steam reforming

Ni/Al2O3 catalysts containing 5 wt% of Ni and modified by addition of CaO (0–5 wt%) were tested in ethanol steam reforming reaction in order to reduce the dehydration ethanol reaction, which produces ethylene that may polymerize and produce coke. The catalysts were prepared by impregnation (I) and co-precipitation (C) methods. All catalysts were investigated for ethanol steam reforming and the catalytic performance was compared in terms of additive addition. The catalysts 5Ni–5Ca/Al (I) and 5Ni–5Ca/Al (C) were less selective to ethylene production and therefore were characterized by the following techniques: energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), temperature programmed reduction (TPR), X-ray absorption near edge structure (XANES), specific surface area by the BET method, scanning electron microcopy (SEM) and isopropanol decomposition reaction. By comparing the catalysts, the 5Ni–5Ca/Al (I) catalyst presented the lowest acidity and carbon deposition, and also presented no deactivation in 24 h of catalytic test.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► CaO into Ni/γ-Al2O3 catalysts modified the catalytic performance in ESR. ► Catalysts containing CaO did not undergo Ni species oxidation during the ESR. ► The acidity of the support was reduced with the addition of calcium. ► Impregnation method was more efficient in reducing support acidity.