Measurement and statistics of single pellet mechanical strength of differently shaped catalysts

Mechanical-strength measurement methods for differently shaped solid catalysts, such as crushing, knife-edge cutting and three-point bending have been discussed. The strength data were correlated by Weibull distribution. Experimental results show that, except for the crushing strength test on extruded catalysts, all strength tests have a single fracture mode, and the strength failures are due to brittle fracture, originating from tensile stress concentration at the edges of the existing flaws in the catalyst pellets. The suitability of different test methods for spheres, tablets and extrudates, respectively, are discussed. It is concluded that the crushing test is a satisfactory method for spheres, and crushing and cutting tests are both suitable for tablets, while cutting and bending tests are appropriate for extrudates.