Synthesis and composition The basic compounds for the production of polyphosphoric acid (PPA) are phosphorus pentoxide (P2O5) and phosphoric acid (H3PO4), as shown in Figure 2. Phosphorus is first oxidized to phosphorus pentoxide, which crystallizes as P4O10. Upon its reaction with water, phosphoric acid is produced.

Application

Polyphosphoric acid can be used in the manufacture of special supported catalysts, e. g. for use in the production of cumene from benzene. Polyphosphoric acid can be used in the descaling and brightening of metal surfaces. Polyphosphoric acid is suitable for the drying of gas streams.