A tetravalent metal diphosphonate-phosphite composition definable by the following general formula: M(O.sub.3 P--R--PO.sub.3).sub.1-x (HPO.sub.3).sub.2x (I) is described where: M is a tetravalent metal; x varies from 0.5 to 0.66; R is an organic radical of bivalent aromatic type, carrying side groups which increase its steric hindrance. The composition is in the form of a crystalline solid with a type .alpha. layered structure with the diphosphonic groups positioned to join said layers together by a covalent bond (pillared compounds). It has a B.E.T. surface area from 300 to 500 m.sup.2 /g depending on the nature of R in formula (I), and a porosity in the micropore radius range of less than 20 .ANG. (Angstrom), such micropores contributing to the extent of more than 95% of the total area for the most crystalline materials.
描述了一种可由以下通式定义的四价
金属
二膦酸酯-
亚磷酸酯组成的化合物:M(O.sub.3 P-R-PO.sub.3).sub.1-x(HPO.sub.3).sub.2x(I),其中:M是四价
金属;x的变化范围为0.5至0.66;R是具有增加其立体位阻的侧基的二价芳香型有机基团。该组成物为具有α型层状结构的晶体固体,
二膦酸基团通过共价键连接这些层(支撑化合物)。它具有300至500 m.sup.2 /g的B.E.T.表面积,取决于式(I)中R的性质,并且在小于20 .ANG.(埃)的微孔半径范围内具有孔隙度,这些微孔对于最晶体材料的总面积贡献超过95%。