INTERACTION OF PHOSPHORUS TRICHLORIDE WITH ZEOLITES

The paper presents a detailed Al-27, Si-29, and P-31 n.m.r, and i.r, s tudy of the interaction of zeolites with PCl3. The faujasite framework collapses upon the PCl3 treatment, whereas the mordenite framework is more stable. Phosphorus can be incorporated into zeolites as surface phosphite or phosphate groups but cannot be introduced in a tetrahedra l framework position. HM-MOR was dealuminated with PCl3 in one step, w hereas the HY-FAU was first dealuminated with SiCl4 followed by a COCl 2 treatment, and finally dealumination was completed with PCl3. The HM -MOR sample is only partially dealuminated, as confirmed by Si-29 and Al-27 n.m.r. data. The dealumination of HY-FAU zeolite is quasi-comple te, although a high amount of amorphous aluminosilicate is also formed during the dealumination steps. P-31 n.m.r, data show the presence of dihydrogenophosphate SiOP=O(OH)(2) and phosphite (SiO)(2)P=O(H) group s attached to the surface of both zeolites. Infrared data reveal the p resence of the phosphite group. Part of the phosphorus is found in a c rystalline aluminophosphate phase in the HM-MOR sample, but the alumin ophosphate phase of the Y zeolite sample proved to be amorphous with t he P/Al molar ratio much lower than unity.