Spent refinery catalyst as a synergistic agent in intumescent formulations: influence of the catalyst's particle size and constituents

Spent oil-cracking catalyst from the FCC process was incorporated into an ammonium polyphosphate and pentaerythritol intumescent mixture, both as received, and after milling and sifting. The influence of the catalyst's average particle size on flame retardancy performance was investigated by UL-94 rating standard, limiting oxygen index (LOI), thermogravimetric analysis (TGA) and cone calorimetry. The effect of each of the catalyst's components on the fire resistance of the final composite was also studied. The results show that the best flame-retarding properties are obtained with the finest catalyst fraction and that, of all its components, only the silica-aluminates, such as kaolin and zeolite, affect flame performance to a significant extent.