ELSEVIER Interaction of phosphorus trichloride with zeolites I. Hanms, I. Kiricsi, and P. Fejes Applied Chemistry Department, Jbzsef Attila University, Szeged, Hungary A. Fonseca and J. B.Nagy Laboratoire de R.M.N, Facultes Universitaires Notre-Dame de la Paix, Namur, Belgium W.O. Parker, Jr. Eniricerche SPA, Milano, Italy Z. Szendi Organic Chemistry Department, Jksef Atilla University, Szeged, Hungary The paper presents a detailed “AI, “Si, and 31P n.m.r. and i.r. study of the interaction of zeolites with PCI,. The faujasite framework collapses upon the PCI, 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 tetrahedral framework position. HM-MOR was dealuminated with PCI, in one step, whereas the HY-FAU was first dealuminated with SiCI, followed by a COCI, treatment, and finally dealumination was completed with PCI,. The HM-MOR sample is only partially dealuminated, as confirmed by “Si and *‘AI n.m.r. data. The dealumi- nation of HY-FAU zeolite is quasi-complete, although a high amount of amorphous aluminosil- icate is also formed during the dealumination steps. 31P n.m.r. data show the presence of dihy- drogenophosphate SiOP=O(OH), and phosphite (SiO),P=O(H) groups attached to the surface of both zeolites. Infrared data reveal the presence of the phosphite group. Part of the phosphorus is found in a crystalline aluminophosphate phase in the HM-MOR sample, but the aluminophos- phate phase of the Y zeolite sample proved to be amorphous with the P/AI molar ratio much lower than unity. Keywords: Zeolite Y; mordenite; dealumination; PCI,, i.r.; MAS n.m.r INTRODUCTION Generally the reactions of metal or nonmetal halo- genides with zeolites can be divided into two main groups. (1) The reactant interacts exclusively with the charge-compensating cations, the nature of active cen- ters changes, leading to materials of different catalytic activities. (2) The reactant attacks aluminum as a framework constituent and removes it from the skele- ton. This results in an (at least partially) dealuminated zeolite, thereby causing a change in the nature and concentration of catalytically active sites, an increase in the thermal and hydrothermal stability of zeolite. Fi- nally, this treatment exerts some influence upon the pore structure as well. Among the potentially active agents, in the sense out- lined above, halides and other derivatives of phospho- Address reprint requests to Prof. B. Nagy at the Laboratoire de R.M.N., Facultes Universitaires Notre-Dame de la Paix, B-5000 Namur, Rue de Bruxelles 61, Belgium. Received 26 January 1995; accepted 8 August 1995 Zeolites 16:142-148, 1996 0 Elsevier Science Inc. 1996 655 Avenue of the Americas, New York, NY 10010 rus were also considered. Papers dealing with interac- tions of phosphorus compounds and zeolites claim the following effects: (1) decreased acidity; (2) decreased channel size; (3) blockage of the acid sites on the ex- ternal surface; and (4) dealumination of zeolites with simultaneous formation of different phosphorus- and/ or aluminum-containing compounds within the pore system. Three different types of phosphorus compounds have been used for modification of the acidity of zeolites. Authors applying phosphorus compounds such as triphenylphosphine or trimethylphosphine sug- gested that phosphorus interacts with acid sites on the outer or inner surface of zeolite crystals.1-4 Treatment of zeolites with phosphoric acid led to vari- ous P-containing species, a component of which could be identified unequivocally on the basis of 31P A4AS n.m.r. spectra.“-” By the assumptions of these authors, part of the phosphorus builds into the framework, and the other part transforms into either extraframework amorphous aluminum phosphate or crystalline alumi- num phosphate with aluminum removed from the 0144.2449/96/$15.00 SSDI 0144-2449(95)00104-2