Mechanical properties of ZSM-5 extruded catalysts: calcination process optimization using response surface methodology

The mathematical models based on response surface methodology were developed to study the effects of calcination process factors on the mean strength and Weibull modulus of ZSM-5 extruded catalysts. The response surfaces analyses show that the mean strength increases as calcination temperature increases, and the Weibull modulus increases first and then decreases, reaching a peak at 600 degrees C. The mean strength increases with increasing calcination time, while the highest Weibull modulus is obtained as calcination time increases up to the median. The mean strength decreases first and then increases with increasing heating rate, reaching a minimum at 10 degrees C min(-1), while the behavior of Weibull modulus is opposite. The optimal experimental condition could be obtained by optimizing the developed models. And the catalyst under this condition would possess both higher mechanical strength and Weibull modulus, showing more satisfactory mechanical properties. Furthermore, it is indicated that the utilization of response surface methodology could discover important experimental information overlooked through conventional statistical method.