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Since the crystalline aluminosilicate is a one- of the A zeolite, known as “molecular sieves,”5 component catalyst, as distinguished from multi- having “port” sizes of 4 to 5 A. Such observations, component or amorphous catalysts, an opportunity in addition to providing an unusual type of catis afforded for detailed study of the compositional alytic selectivity, support the concept of “intraand structural factors which impart catalytic crystalline catalysis,” in contrast to activity of the activity for this reaction. exterior surface of crystals. With the Ca++ form of the A crystal, we have SOCONY MOBILOIL COMPANY RESEARCH DEPARTMENT GEORGET. KERR carried out the selective dehydration of 1-butanol PAULSBORO, NEWJERSEY GEORGEC. JOHNSON in the presence of isobutyl alcohol. Conventional ~LECEIVED FEBRUARY 25, 1960 silica-alumina catalyst dehydrates both alcohols at comparable rates. In contrast to the Ca++form the “X” crystal, we observed cracking of only INTRACRYSTALLINE AND MOLECULAR- of n-paraffins over this solid to only straight chain SHAPE-SELECTIVECATALYSISBY ZEOLITE products, consistent with molecular sieve action SALTS which does not allow egress of isomeric products. As an example of imparted activity, molecularsir: shape-selective hydrogenation catalysts have been We have foulid unexpected intrinsic catalytic prepared by incorporation of platinum in the A activities on synthetic crystalline inorganic zeolite crystal. We have selectively hydrogenated 1salts. 1 . 2 butene in a mixture of 1-butene and 2-Me-propene. The sodium aluminosilicate isostructural with In a mixture of equal volumes of 1-butene, isofaujasite, known as “13X,”3 is more active for the butene and hydrogen, at 25O with a contact tune cracking of normal paraffins than conventional of ca. 0.1 sec., 50yoof only the 1-butene was consilica-alumina, cracking catalysts (10% ~ 1 1 2 0 3 , verted to butane. A platinum on alumina catalyst g2O m.*,/g.:iudace area). If one replaces most of converted approximately equal quantities of both the Na+ by (la++, the cracking activity is further olefins. increased (Table I). The products from the Cat+ Sot all catalytic activities exhibited by the form resemble those from silica-alumina. Wowever, the products from t,he S a + form n.re free of zeolites need be intracrystalline. For example. with a n X zeolite of 4k.port size we have observed branched-chain structures. Patdysis for the hydration of ethylene oxide to TARLE r ethylene glycol and polyglycols with no hindrance effect of port size in evidence. Herr the catalytic W D E C A N E (:R.4CKIXG. 3 HR. ~ P E H A T I O N , 470”, T = activity appears to be located at the euternsi surface 9 SEC., 1 ATM. of the crvstallites. IsoTsoOlefins in vo butane: pentane: crncketl !n conventional surface catalysis the termination Decane n-butane n-pentano products. Cntalytic S&I converted ratio rntio wt. Sr, ( t i a three-dimensional solid structure is considereci Silica-alumina 25 3.1 3 0 37 to he the locus of actimty. For these zeolites, the Na-aluminosilicate! X 32 0.0 0 0 62 concept of surface loses its conventional meaning Ca-aluminosilicate, S 39 1. 1 2 4 30 and the molecular participants can find themselves In contrast with its high catalytic activity for the exposed to unusual coulomb fields. W t t wish to acknowledge contributions made X C I cracking of paraffins, the Na+ form is inact,ive for the dealkylation of isopropylbenzene even at 510’; various phases of the above work by fl. W. Maathowever, the (:a++ form produces extensive conver- man, It. L. Golden, E. Mower, arid G ’f. Km-. $ion at 465‘. Alpha-pinene undergoes no reaction Socohiv ~ I O B OIL I L COUPANY, INC. P B. u EISZ when refluxed with the Na+ form, but is converted l’AUL5BORO LABORATORIES I’il’l \HORO, J. V J FRII,E~TF extensively to camphene by the Ca++salt. R r C L I V E D FEBRI‘ARY 25, 1qM) The observed cracking activities are unexpected _ _ _ _ _ because of the cwmmon view that acid it,^" is a (5) 1) W Brrch, rtl I 4 m Chpm Soc . 7 8 , i W t 3 tICLiF) requirement arid the common experience o i poisoning by alkali and alkaline earth metals on conventional si1ic:ious cracking catalyst~s. We believe that the locus of catalytic activities THE NATURE OF THE SPECIES RESPONresides in the extensively developed interstkes of SIBLE FOR THE LONG WAVE LENGTH the X crystai. These interstices are accessible to ABSORPTION BANJ IN ACIDIC all molecules with critical diameters less than ea. SOLUTIONS OF OLEFINS 9A., Le., to ztll of t>hereactant and product molerules described above. Sir: We have heen able to demonstrate molecularDistinc.tly different electronic spectra are obshape-selective catalysis by utilizing intrinsic, t,ained from solutions of arylalkenes in .rmngly catalytic activities described above. or artificially acaidic. and weakly acidic media. ‘rhus, while inrorporat,ec.lc:Ltalytic materials within salt forms solutions of 1.1-diphenylcthylene (I)PE) in con: l i D. $4’. Brock, el d., J . ilm. Chem. Soc., 78, XM3 ( I D X ) . rcntrated sulfuric acid exhihit only the spectrum “2) R. X.Barrer. er ai., 7’rnn.v. Faraday Yor.. 63, 1 1 I 1 (1957). (Amax. = 423 mp; e = 4.7 X IO4 pm.-I mole-’ ‘3) Lindi, Air Prudiicts Co.. Tonawanda. New York. liter) due to the expected methyldiphenylcarbonium ‘ 4 ) E.@.. A . G. Ohlad, at al.. “.4dvances in (’atnlysis.” Vol. 1x1, ion,’ solutions in weakly acid media. e.g., sulfuric4cadernic I’rew N e w T o r k . N. Y . , 1951, PIX.199-L’&7.
