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US3415736.Pdf 3,415,736 United States Patent Office Patented Dec. 10, 1968 1. 2 3,415,736 It is contemplated that the silica may exceed 4.5 moles, LTHUM-CONTAINING CRYSTALLINE going up to 5.5 to 6 moles, and also that it may be as ALUMINOSILICATE low as 2.0 moles. Preferably the composition is defined Julius Ciric, Pitman, N.J., assignor to Mobil Oil as follows: 'Corporation, a corporation of New York Filed Sept. 20, 1965, Ser. No. 488,443 0.3-0.8LiO: 0.7-0.2Na2O:Al2O3: 16 Claims. (C. 208-111) 2.8-4SiO2:0-9H2O (III) For convenience, the new material, which may comprise a number of species as is evident from Formula (II), ABSTRACT OF THE DISCLOSURE O may be referred to as Zeolite ZSM-3, or simply as ZSM A new zeolite composition having a characteristic X 3. Zeolite ZSM-3 may be identified and distinguished by ray diffraction pattern and having a composition, in X-ray diffraction analysis as well as by composition. terms of mole ratios of oxides: Following are data of an X-ray powder diffraction pat 0.05-0.8LiO:0.95-0.2Na2O:Al2O3:2.0-6SiO2:0-9H2O tern of a typical example of ZSM-3, it being understood a process for making the same and a process for utilizing 15 that all species thereof exhibit essentially the same pat a catalyst comprising the same for hydrocarbon con tern. version. TABLE 1. Interplanar Relative Comment SSSS Spacing, d.A.* Intensity This invention relates to a novel class of crystalline 15.50 111 14.37 S aluminosilicates and to methods for preparing the same. 13,39 ??? More specifically, it relates to new crystalline lithium 8.89 1 7.53 sodium aluminosilicates and their preparation. 7.38 ??1 Very broad Both natural and synthetic crystalline aluminosilicates 5.77 ??1 Broad. 5.0 W are known and may generally be described as alumino 4.81 w silicates of ordered internal structure having the follow 4.42 ?l 4.2.1 ?y" Do. ing general formula: 4.5 W" Do. 3.82 w Very broad. 3.75 w Broad. 3.47 w Do. t (I) 3.34 ?1 3.23 W ID?. where M is a cation, n is its valence, Y the moles of silica, 3, 20 W D0. and Z the moles of the water of hydration. 3.05 O. When water of hydration is removed from the crys 2.94 W7 talline aluminosilicates, highly porous crystalline bodies 35 NOTE.-w=weak; S=Strong; m=medium; www = very, very weak. are formed which contain extremely large adsorption Standard techniques were employed to obtain the fore areas inside each crystal. Cavities in the crystal struc going data. The radiation was the Kalpha C doublet of ture lead to internal pores and form an interconnecting copper, and a Geiger counter spectrometer with a strip network of passages. The size of the pores is substantially chart pen recorder was used. The peak heights, I and constant, and this property has led to the use of crystalline 40 the positions as a function of 2 times theta, where theta aluminosilicates for the separation of materials accord is the Bragg angle, were read from the spectrometer ing to molecular size or shape. For this reason, the crys chart. From these, the relative intensities, 100 I/I where talline aluminosilicates have sometimes been referred I is the intensity of the strongest line or peak, and d to as molecular sieves. They are also Zeolitic. (obs.), the interplanar spacing in A., corresponding to the The crystalline structure of Such molecular sieves con 45 sists basically of three-dimensional frameworks of SiO4 recorded lines, were calculated. In Table 1 the relative and AlO4 tetrahedra. The tetrahedra are cross-linked by intensities are given in terms of the symbols w=weak, the sharing of oxygen atoms, and the electrovalence of S=strong, m= medium, and vyw=very, very weak. the tetrahedra containing aluminum is balanced by the in Zeolite ZSM-3 is a large pore Zeolite of the faujasite clusion in the crystal of a cation (M in Formula I), e.g., 50 type, by which is meant that it exhibits an X-ray diffraction alkali metal or alkaline earth metal ions or other cationic pattern similar to that of faujasite, although there are metals and various combinations thereof. These cations significant differences. The pores are large enough to sorb are generally readily replaced by conventional ion-ex cyclohexane. Thus, a specific ZSM-3 zeolite (completely change techniques. dehydrated) of the formula: The spaces in the crystals between the tetrahedra 55 0.4NaO:0.6LiO: AlO3:3.1SiO, (IV) ordinarily are occupied by water. When the crystals are was observed to adsorb 16.1 g. cyclohexane per 100 g. treated to remove the water, the spaces remaining are of zeolite; it also adsorbed 25.2 g. water per 100 g. of available for adsorption of other molecules of a size and zeolite. Crystals of ZSM-3 have a hexagonal shape, as shape which permits their entry into the pores of the determined by electron miscroscopy. The lithium in structure. 60 ZSM-3 is zeolitic and completely exchangeable; its Molecular sieves have found application in a variety of amount exceeds 0.05, preferably 0.3 equivalent of lithium processes which include ion exchange, selective adsorp per gram atom of aluminum, i.e., the aluminum that is tion and separation of compounds having different molec present in the framework structure of the aluminosilicate. ular dimensions such as hydrocarbon isomers, and the Zeolite ZSM-3 is capable of being ion exchanged to catalytic conversion of organic materials, especially cata 65 lytic cracking processes. partially or completely replace the sodium cation by other According to the invention, the composition of the new cations. During this step, part or all of the lithium cation aluminosilicate, in terms of mole ratios of oxides, may is also replaced by the replacing cation. It will be under be set forth as follows: stood that the spatial arrangement of the aluminum, 70 silicon, and oxygen atoms, which form the basic crystal 0.05-0.8LiO:0.95-0.2Na2O:AlO3: lattice of ZSM-3, remains essentially unchanged by the 2.8-4.5SiO2:0-9H2O (III) described replacement of sodium and lithium, and that 3,415,736 3. 4. the X-ray powder diffraction pattern of the ion-exchanged association with one of the above components, preferably material is essentially the same as that set forth in Table a platinum metal. 1. The replacing cations include monovalent, divalent, The zeolite may also be employed as an adsorbent, trivalent, quadrivalent cations, and they may be selected after at least partial dehydration, a step which may be from ions of the following: metals of Group IA of the carried out by heating the zeolite to 200-600 C. in an Periodic Table, such as potassium; metals of Group IB, inert atmosphere, such as air or nitrogen, under such as silver; metals of Group IIA, such as magnesium, atmospheric or reduced pressure, or by maintaining the calcium and strontium; metals of the transition metals, zeolite under vacuum at room temperature or above for such as those of atomic numbers 21-28, 39-46, and 72-78, a suitable time. As an example, zeolite ZSM-3 may serve inclusive; metals of the actinide series; and rare earth to adsorb and remove water from natural gas. metals such as cerium, lanthanum, praseodymium, 10 Zeolite ZSM-3 may be suitably prepared by forming a neodymium, samarium and mixtures thereof with each reaction mixture containing lithium oxide, sodium oxide, other and the other rare earths. Other useful replacing alumina, silica, and water and having a composition, in cations are ammonium, alkylammonium, and arylam terms of mole ratios of oxides, falling within the follow monium cations, these leading to a product which, on ing ranges: calcining, decomposes to the hydrogen form. Ion ex TABLE 2 change of the zeolite may be accomplished conventionally, as by packing the zeolite in the form of beds in a series Preferred Broad Li2Of Li2O-Na2O.--- -- 0.25:1 to 0.82:---- 0.2:1 to 0.9:1. of vertical columns and successively passing through the Li2O.--Na2OfSiO2 - 0.6:1 to 1.33:1 0.55:1 to 2.5:1. beds a water solution of a soluble salt of the cation to 20 SiO2/Al2O3----- - 4:1 to 16:1-- 2:1 to 32:1. be introduced into the Zeolite; and then to change the H2O/Li2O-H-Na2 --- 40:1 to 120:1------- 20:1 to 300:1. flow from the first bed to a succeeding one as the zeolite Satisfactory crystallization can be carried out by main in the first bed becomes ion exchanged to the desired taining the mixture at temperatures of about 20 to 120 extent. C., the pressure being atmospheric or at least that cor It will be seen from the preceding paragraph that responding to the vapor pressure of water in equilibrium Zeolite ZSM-3 may be more broadly defined, in terms of with the mixture of reactants. The reaction period may oxides, as follows: extend from several hours to several days. At lower tem peratures in the foregoing range, and at lower alkali to silica ratios, the reaction period tends to be longer. In 30 any event, the mixture is kept at the selected temperature where M represents at least one cation having a valence until the desired crystalline zeolite product is formed. of not more than 3 or 4, and n represents the valence of The zeolite crystals are then separated from the mother M.
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