COMPARISON OF PARTICLE-SIZE OF CRACKING CATALYST DETERMINED BY LASER-LIGHT SCATTERING AND DRY SIEVE-METHODS

A method of interconversion of dry sieve and laser light scattering pa rticle size values has been developed for cracking catalysts. Values o btained by light scattering techniques were consistently larger than t hose obtained by dry sieve analysis. The differences were primarily du e to lack of sphericity of the particles. The particle size distributi on determined by light scattering techniques was based on an average p article diameter. Conversely, the sieve measured the smallest diameter of the particle which can pass through the opening. Microscopic exami nations of commercial cracking catalysts confirmed their nonuniformity . The sphericity of the catalyst particles decreased as particle size increased. Therefore, the divergence between the laser light scatterin g and dry sieving value became greater as the catalyst particle size i ncreased.