Chemistry of inorganic compounds – Silicon or compound thereof – Oxygen containing
Patent
1980-12-09
1982-12-28
Meros, Edward J.
Chemistry of inorganic compounds
Silicon or compound thereof
Oxygen containing
252431N, 252455Z, 423328, 546 11, C01B 3328
Patent
active
043661351
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The prior art described synthetic zeolites, different methods of preparing same and the use of synthetic or natural zeolites in the catalytic conversion of hydrocarbons. The zeolites according to the invention are very stable to heat and acids, what makes them particularly suited for processes involving high temperatures, such as isomerization of xylenes; other advantages will appear from the description.
DESCRIPTION OF THE INVENTION
The invention relates to a method for preparing zeolites having the formula: (1.5.+-.0.6) M.sub.2
O.Al.sub.2 O.sub.3.ySiO.sub.2.zH.sub.2 O, where y ranges from 20 to 90, preferably from 40 to 80 and z from 2 to 12, preferably from 3 to 8, M is at least one cation and n is the valence of M, and where Al and Si may be optionally replaced, at least partially, by Ga and Ge respectively. M is preferably selected from the monovalent cations, the cations of the rare earths, the cations of the 2nd and 8th Groups of the Periodic System, and mixtures thereof; in particular the cations can be selected from alkaline ions, hydrogen ion, ammonium ion, diethyl-piperidinium ion and mixtures thereof. The formula of diethyl-piperidinium ion (DEPP).sup.+ is: ##STR1## The method according to the invention comprises the admixture of (DEPP)OH or of a salt thereof with H.sub.2 O and with at least one compound containing Na, one compound containing a metal selected from amongst Al, Ga and mixtures thereof and one compound containing an element selected from amongst Si, Ge and mixtures thereof, the molar ratios, expressed as oxides ratios, being comprised in the following ranges;
According to a preferred embodiment, the cation dilution ratios, namely the molar ratios: respectively equal to or higher than 160 (preferably 190) and 80 (preferably 90) and the r2:r1 ratio (namely the sodium factor SF) is equal to or lower than 0.6 (preferably between 0.20 and 0.60). A very important factor, the cation mineralization factor (CMF), defined as:
The synthesis can be carried out under autogenous pressure, in an autoclave equipped with stirrer, in one or more steps at, between 130.degree. to 200.degree. C. for one or more days, and preferably between 160.degree. to 200.degree. C.; the solid is then separated from the liquid, for instance by filtration or centrifugation. Sources of Si, Al, Ga, Ge and Na can be compounds providing for the corresponding oxides, such as Al silicates, Na aluminates, Na silicates, silica hydrosol, silica gel, silicic acid and NaOH; (DEPP).sup.++ ion can be provided for by the hydroxide, a halide (in particular bromide or iodide), a sulphate, a phosphate or the nitrate. Zeolites can undergo exchange of the original ion with the proton (from acids) or with the ammonium ion; it is possible to obtain zeolites in the acid form by exchange with ammonium (using for instance NH.sub.4 Cl, NH.sub.4 NO.sub.3 or NH.sub.4 OH) and by successive calcination of the zeolite. The ammonium ion decomposes and a proton is left in the structure; the protons (or the original ions) can be exchanged with all the cations of the Periodic System, in particular with the cations of the 8th group, according to known technologies. The new zeolites can be used in acid form or partially exchanged with different ions; it is possible to add active components by means of known techniques, such as dry or wet impregnation and mechanical mixing.
Zeolites can be prepared in a variety of shapes, for instance in granules or extrudates; in such cases it is advisable to admix the obtained powder with a binding material, such as clays, silica, alumina or other metal oxides. Before being used, zeolites should be at least partially dehydrated, for example by a heat-treatment at high temperatures, under vacuum or not; activation in the air, at temperatures from 450.degree. C. to the temperature at which the structural collapse of the zeolite starts (about 850.degree. C.) is recommendable.
The invention relates also to the use of the new zeolites for the conversion of hydrocarbons by means of acid-ca
REFERENCES:
patent: 3702886 (1972-11-01), Argauer et al.
patent: 4000248 (1976-12-01), Martin
patent: 4205053 (1980-05-01), Rollmann et al.
patent: 4251499 (1981-02-01), Nanne et al.
Covini Romano
Genoni Fausto
Le Van Mao Raymond
Moretti Enrico
Pilati Orlando
Meros Edward J.
Montedison S.p.A.
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