Characterization and modification of Indonesian natural zeolites and their properties for hydrocracking of a paraffin

Attempting to utilize natural zeolites as catalysts, characterization and modification of two kinds of those produced in Indonesia (Z1 and Z2) were carried out and their properties for hydrocracking of paraffins were evaluated using n-hexadecane as a petroleum model compound. The Z1 and Z2 samples were first treated with 6 N HCl at 90°C for 0.5 h or 20 h. X-Ray diffraction analysis of the HCl-treated samples (Z1-0.5 h, Z2-0.5 h, Z1-20 h, and Z2-20 h), as well as Z1 and Z2, indicated that both original samples mainly consist of mordenite type crystalline matter and the acid treatment removes some of crystalline impurities X-Ray fluorescence data revealed that Z1 and Z2 have Si/Al ratios of 4.3 and 3.1, respectively, and the treatment increases the ratio by dealumination as expected. The examination of hydrocracking properties showed that Z1 and Z2 have similar catalytic properties and the acid treatment considerably improves their activities. On the other hand, Z1- and Z2-20 h were less active than were Z1- and Z2-0.5 h, respectively. NH₃-TPD and ²⁹Si MAS NMR suggested that this may be due to the significant decrease of active acid sites by the prolonged treatment. It was also found that the loading of a small amount of nickel (0.8 wt%) onto Z1-0.5 h by ion exchange, significantly improves the catalytic property; the conversion of the paraffin was comparable with that using a synthetic H-mordenite.