The effect of oxalic acid and NaOH treatments on the character of Wonosari natural zeolite as Ni, Cu, and Zn metal support catalyst for hydrocracking of castor oil

The hierarchical zeolites were successfully prepared via oxalic acid and NaOH treatment of natural zeolite (ZA) collected from Wonosari, Indonesia. Mordenite and clinoptilolite are the main components found in the ZA, as shown in the XRD pattern of ZA. Oxalic acid, a weak organic acid, enhanced the Si/Al ratio accompanied by an increase in the acidity due to the pore opening of zeolite structure which was proven by the raising of V Micro. Further treatment using NaOH generated a more mesoporous system in the framework. The shift of asymmetric stretching of the T—O—T (T = Si or Al) group at 1300–1000 cm−1 was observed in the FTIR spectra as a consequence of the change in the Si/Al ratio after both treatments. The XRD profile of zeolites was maintained throughout the treatments. The catalytic activity of ZA improved after both treatments in terms of % of liquid fraction towards hydrocracking of castor oil. Interestingly, incorporating Ni, Cu, and Zn onto the treated ZA expanded the surface area except for the Zn metal due to the aggregation. Treated ZA with Ni incorporation exhibited the best catalytic activity because of the synergistic effect between the support and transition metal. These catalysts could be used up to three times without significant loss in the catalytic activity.