CA1246612A - Zeolite rho as catalyst for conversion of methanol and ammonia to dimethylamine - Google Patents

Abstract

TITLE

Zeolite Rho as Catalyst for Conversion of Methanol and Ammonia to Dimethylamine ABSTRACT
A process is provided for producing dimethylamine, comprising reacting methanol and/or dimethylether and ammonia, in amounts sufficient to provide a carbon/nitrogen (C/N) ratio of from about 0.2 to about 1.5, at a temperature from about 250°C
to about 450°C, in the presence of a catalytic amount of an acidic zeolite rho.

Description

TITLE
Zeolite Rho as Cataly~t for Conve~ion of Methanol and ~mmonia to Dimethyla~ine BACKGROUND OF THE INV~NTION
This invention ~nvol~es a proce~s fo~ making amine~, particularly dimethylamine, in which methanol andior dimethylethe~ and ammonia a~e con~acted in the presence of a ~elected zeolite cat~ly6t.
Methylamines are genelally prepared în indu~t~ial quanti~ies by continuou~ ~eac~ion of 1~ methanol and ammonia in the pr~ence of a ~ilica-alu~ina catalyst. The ~eactants are typically combined in the vapor pha~e, at temperature~ in the ~ange of 300 to 500C, and at elevated pressure~.
Trimethylamine is the ~rincipal component of the ce~ulting product ~tream, accompanied by le66er amount6 of monomet~ylamine and dimethylamine. From a comme~cial ~tandpoint, the mo~t valued producC of the reaction i~ dimethylamine, in view of itfi wide6pread ~ndustrial use a~ a chemical intermediate.
Acco~dingly, a major objectiYe of tho~e seeking to enhance the commercial efficiency of this process ~a~
been to improve overall yields of dimethylamine, and to a le~er extent, monomethylamine, rel~tive to tri-methylamine. Among the app~oaches taken to mee~ thi~
Z5 objective a~e recycling of trimethylamine, adju~t~ent of the ratio of methanol to ammonia react~nt6, and use o~ 6elected dehydrating or aminating ~a~aly6t specie~. Due to the com~e~c~al imeortance of the proces~, a rather exten~ive compendium of patent~ and o~her contributions to the ~echnical literature ha6 resulted. Re~re~entati~e referen~es gQne~ally rele~ant to ~he field of ~he plefient inYentio~ ar~
~ummariz~d in She follcwing parayra~h~.

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Swallen, U.S. Pa~nt 1.926,6910 di~clo~e~ a p~oce6~ for producing dimethylamine by di~propo~tion-a~ing monomethylamine over dehyd~ating or aminating cataly~t~ ~uch afi alumina, silica. thocia. aluminum 6ilicate or partially dehydrated aluminum trihydrate.
ALnold, U.S. Pa~ent 1~9~2.9'~5, des~ribe~ a proce~s for catalytic syn~hesi~ o~ amine~ from alcohols and ammonia which employs as cataly~t a -dehyd~a~ing oxide, e.g., alumina, depo~i~ed on the ~urface of a pOlOU~, rigid gel, e.g., ~ilica gel.
Arnold, V.S. Paten~ Re. 19,632, disclo~es a proce~6 improvement in which trimethylamine i~ introduced with the methanol and ammonia reactant~ to ~hift reaction equilibrium in favor of dimethylamine production.
John~on, B~iti6h Patent No. 422,563, cli~-clo~e~ a proca~s fo~ p~oducing aliphatic amine~
involving heating an alcohol or ether under a pres~ure oE more than about 50 atmosphe~es in the presence of a "cataly6t capable of 6plitting off water" ~e.g., alumina), with an exce~s of ammonia and optionally with addition of ~rimary amine to the reaction mixture.
Go~horn, U.S. Patent 2,349,222. discloses u~e of gLanular alumina coated with one or mo~e oxide~ of nickel, cobalt, or chromium a6 a cataly~t for alkylation of ammonia to p~oduce alkyl amine6.
Go~horn, V.S. Pa~ents 2.394,515 and 2,394.516, di~clo~e6 u~e as cataly6t of an aluminum salt or oxide coated with 6ilica and vanadium or molybdenum oxide.
Smi~h, U.S0 Patent Z,456,599, di~clo~es a proce~6 improvement wherein water i~ added eo a re~ctant feed mixtu~e of methanol and am~onia to repre~ formatlon of tertiary amine in ~avor of 3s primary and secondary amine.

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Markiewitz, U.S. Patent 3,278,598, disclo~e~
use of a rhodium, palladium, or ruthenium cocataly~t in conjunction with Raney metal~ ~o i~rease produc-ti~n ~f ~econdary amine~ from ~e reaction o~
alcohol~ and ammonia.
Rostelli et al., A. I. Ch. E. Journal 12:292 (1966~ de~cribe studies of transmethylation reaction~
of monome~hrlamine and dimethyl~mine over ~ontmoril-lonite, a hydrated magnesium or calcium oxide-containing aluminosilicate having a porous la~tice structure. For trans~ethylation of ~onomethylami~e, thi~ work indicated that ~eaction ~a~te wa6 directly proportional to reac~ant partial pre~ure, indica~ing that the rate-determining event i~ adsorption of reactant to the cataly~t surface.
Hamilton, U.S. Patent 3,384,667, de6cribes alkylation of ammonia in the pre~ence of a dehydrated crystalline alimino~ilicate catalyst having pores of a diamete~ peEmitting ab60rption of primar~ and ~econdary, but not tectiary, amine product6.
Leonard, U.S. Patent 3,387,032, disclose6 a eroce6s foc reacting a~monia with methanol and~or ; dimethyl ether in the ~re~ence of a cataly~t consi6t-ing of a silica gel ba~e impraynated with 10-15%
alumina which is first ~team-deac~ivat~d and then treated with ~ilver, chenium, molybdenum. or cobalt ion~ to peomote 6electivity for dimethyla~ine.
Kaeding, U.S. Patent 4,082,805, disclo~es ufie of a c~y6talline aluminosilicate or zeolite cataly~t having the ~tructure of ZSM-5, ~SM-ll or ZS~-21 in a process for producing amine~ by eeaction ; of ammo~ia w~th Cl-C5 al~ohols at elevated temperatu~e~ and pre~sure6.
: Parker et al., U.S. Patent 4,191.709, de6ccibe use of a hydrogen form of zeolite FU-l or .

lZ9L~

zeolite FU-l in which sGme or all of the proton~ have been ~eplaced by bivalen~ or ~rivalent cations.
. Weigert, U.S. Patent 4,25~,061. di~clo~e~ a prOCe~8 in which ~roduction of monomethylamine i8 enhanced by reacting methanol and ammonia in amounts ~ufficient to provide a CtN ratio of 0.5 to 1.5 over a cataly~t 6elected from ~a) mordenite wherein ~he primary cation i~
Li, Na, HNa having at leas~ 2~ Na by weight, K, Ca, Sr, Ba, Ce, Zn or Cr:
(b~ ferrierite ~herein the primary metal ~ation i~ Li, Na, K, Ca. Sr, Ba, Ce or Fe;
(c) erionite ore;
(d) calcium ecionite, and (e~ clinoptilolite oce at a temperature of 250-475C and a presfiure of 7-7000 kPa. a contact time, normalized to 7 kPa, of 0,1 So 60 ~e~ond~, and a methanol conver6ion of 15-95%.
A~hina et al., JapaAese published Patent Application No. 56-53887, and ~ochida et al., Journal of CatalY 6 32:313 (1981~, also disclose u~e of mvrdenite zeolite~ to enhance pcoduction of di~ethyl-amine i~ ~lo~ely related variants of the proce~s di~clo6ed by Weigert.
We~gert, U.S. Patent 4,313,0~3, di~closes an improved proce~ for di~propor~ionating monomethyl amine to dime~hylamine and ammonia, comprising 2a5~in~ monomethylamlne over a cry6talline alumino~licate cataly~t ~elected from (a~ mordenite wherQin the primaLy cation i~
Na, HNa having at least 2t Na, ~g, Ca, Sr or Ba;

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(b~ ferrierite wherein ~he p~imary me~al cation i~ Na, K, ~g, Ca, Sr or Ba;
(c) clinoptiloli~e and (d) phillipsi~e:
at a temperature of 250-475C and a pre~sure of 7-7000 kPa . at a feed rate of 0.1-10 ~ram~ of ~onomethylamine per g~am of cataly6t per hour, at a monomethylamine conver6ion of 15-75%.
Coch~an et al., U.S. Patent 4,398,041, de~cribe ~ proce~ fol converting Cl-C4 alcoh~ls to a non-equilibrium controlled di~tribu~ion of primary.
~econdary, and tertiary alkylamine~. The procefi6 di6clo~ed involvefi paE~ing a mixture of reactant alcohol~ and ammonia into a first conversion zone containing a i'~hape-selective" ceystalline alumino6ilicate cataly~t having a pore ~ize ~elective for monoand di~ub~tituted alkylamine products:
dividing the resulting product stream: pa~6ing one portion of thi~ product ~tream to a 6econd conversion zone ~ontaining another c~taly~t having a diffelent pore ~ize di~tribution; and combining the remaini~g portion of the fir6t product ~tream with the product stream of the second conversion zone to yield a non-equilibrium controlled product distributlon. The zeolite cataly6t6 di~closed by thi~ ceference include 5A æeolite. REY zeolite, H-chabazite-erionite.
H-erionite, H-~ordenite~ and H-Y zQolite. Deeba et al.~ publi~hed European Patent ~pplication 008S408, disclo~e a method for improving methanol ~onversion rates co~pri~ing reacting ~ethanol and a~monia over a 3~ highly acidic dehydrated alumino6ilicate satalyfi~
having a silicon to aluminum ratl~ of at lea6t 2.0 : and mani~e~ing microporous diffu~ivity or methylamînes. Deeba et al., ~.S. 4,434,300 di~close a ~ethod for imeroving ~ethanol conver~ion rates in :

the reaction of methanol and ammonia to produce methylamine~ which compri~e~ effecting the reaction in the presence of a ~ac~oporou~, highly a~idic aluminosilicate.
Tomp~ett, U.S. Patent ~,436,938, di~clo6e6 a p~oce6~ for making methylamines compri~ing reacting methanol and/or dime~hyl ether over a binderles~
zeolite A cataly~t. pLeferably a binde~les~ zeolite 5A cata ly5 t .
Currently, methylamine6 are produced using an adiabatic plug flow reac~ol. Although ~pecific condit;ons do va~y depending upon ammonia feed ra~io and am~unt of product recycle, reactor inlet temperatures are yenerally maintaîned ~rom about 310C ~o 340C, and outlet temperature~ generally cun 15 f~om about 400~C to about 430C. The difference between inlet and outlet temperatures i8 due to exothermicity of the reaction and i~ moderated by recycling o~ ammonia and tri~ethylamine. The foregoing temparature~ Lepre~ent a compromi~e between increa6ing production rates at a given reacto~ ~ize, which is favo~ed at higher react;on temperature~, and reducing catalyst deactivation, which i6 minimized at lower reaction temperatur26. ~ ~ore ~ctive ~ataly~t wGuld permit operation at lower reaction ~empera-ture6, increa6ing cataly~t life~ime and/or decrea6ingthe need to ~ecycle ammonia or trimethylamine.
A~ the foregoing di~cu6sion 8ugge6t6, new process improvement~ which optimize dimethylamine yield~ and ~uppress production of trimethylamine and which allow lower reaction temperature~ while maintaining reactor throughput in thi~
widely-practiced procefi~ are of 6ignificant ;nte~e~t to the chemical indu~try.

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SUMMARY OF THE INVENTION
The pre6en~ invention provides a proce~s for p~odu~ing dimethylamine compri~ing reac~ing ~ethanol and/or dimethylether and ammonia, in amoun~6 sufficient ~o provide a carbon~nitrogen (C/N~ ~atio from about 0.2 to about 1.5, at a tem~erature from about 250C to about 450C, in the pre~ence of a catalytic amoun~ of an acidie zeolite rho.
DETAILED DESCRIPTION OF THE [NVENTION
Zeolite~ can be generically described as ~omplex alumino6ilicate~ characterized by a three-dimensional framework fitructure enclosing cavitie~ occupied by ion~ and water ~olecule6, all of which can move with ~ignificant freedom within the zeolite ~atri~. In commercially u~eful zeolite~, the water molecules can be removed fco~ or replaced within the f~amewor~ withou~ ~e6~roying its geometry. Zeol~te6 can be represented by the following formula:

M2/n A12O3 ~ x SiOz y H O
wherein ~ is a cation of valence n, x >2, and y is a number determined by the porosity and the hydration 6tate of the zeolite, senerally from 2 to ~. In na~urally-occurring zeolites, M is princip~lly represented by Na, Ca~ K, Mg and ~a in proportion6 u6ually reflecting thei~ app~oximate geochemical abundance. The cation6 M are 1008ely bound to t~e st~uc~ure and can f~equently be co~eletely or par~ially replaced with other cations by convention~l ion exchanye.
Zeolite ~tructure eon~ist~ of corner-llnked teerah~dra with Al or Si ato~s at center~ of tatrahedra and oxygen a~om6 at ~orners. Such : 7 ,, ~2~6g~

te~rahedra are combined in a well-defined repea~ing ~tructure co~pri~ing variou~ combina~ion~ of 4-, 6-, 8-, 10-, and 12-membered ring~. The re6ulti~g framewoLk consi6~s of regular channel~ and cage6, which impart a u~eful pore structure for catalys;s.
Pore dimen~ions are de~ermined by the geometry of ~he alumino~ilicate tetrahedra forming the zeolite channels or cage~, with nominal opening~ of 2.6 ~ for 6-ringfi, 4.0 A for 8-ring~, and 5.5 A for 10-ring~.
Pore dimensionfi are critical to catalytic performance, ~ince thi6 characteristic determine~
whether reactant ~oleculex can enter and produc~
mole~ules can exi~ the zeolite framework~ In practice, it ha~ been observed that very slight decrea6e~ in ring dimen6ion~ can effectively hinder or block movement of particular ~eactant6 or product wi~hin a zeolite ~tructure.
The pore dimen6ion6 which control acce6~ to the interior of the zeolite are determined not only by the tetrahedra forming the pore opening, but al60 zo by the pre~ence or abfience of ionfi in or near the pore. In ~he cafie of zeolite A, or example, acce~
can be restricted by monovalent ion6, ~uch a6 Na~ or K~, which are ~ituated in or near 8-ring opening~ a~
well a~ 6-~ing openingfi. Acce~ i6 enhanced by divalent ion~, fiuch a~ Ca2+, which are ~ituated only in or near 6-ri~gfi. Thufi KA and NaA exhibit effective pore opening6 of about 0.3 nm and 0.4 nm re~pectively, wherea6 CaA ha~ an effective po~e opening o 0.5 nm.
Useful refe~eQce~ generally relating to zeolite ~t~ucture and characteri~ation include the following:

~eier et al., Atlas of Zeolite Structure Types 3S (International Zeolite A~n. 1978);

; , 8 ~6~j~2 Mumpton, "~a~ural Zeolite~" in Reviews in M~e~L~l~Y 14:1 (lg77);
Smi~h, "OLigin and S~ructure of Zeolite6" in Zeoli~e Che~is~y and ICatalysi~. ACS
Monograph 171 (American Chemic21 Society, 1976).

General_Characteri~tic~ of Zeolite Rho Zeoli~e ~ho, ~he zeol te 6pecie~ employ2d in the p~oce~ of the pre~ent invention, is a ~mall-pore ~ynthe~ic zeolite ~hich can be de~cribed by the formula ~Na.C6)1~A1125i~6096 44 ~2~-The 6tructure and 6ynthe~i~ of thi6 6ynthetic zeolite are de~cribed by Rob~on et al., "5ynthesis and Cry6tal Structu~e oS Zeolite R~o - A ne~ Zeolite Related to Linde Type A", Advances in Chemi6try Selies 121 (A~erican Chemical Society 1973), and :Rob60n, U.S. Pa~ent 3,904,738.
The cationic ~pe~ie~ Na~ and C6~ present in rho zeolites can be exchanged for protons an a conventional ion exchange with ~4 or ~y conver~ion to : an ammoniated for~ ~NH4-rho) whi~h i~ subgequently conYerted to the acid fo~m by calcination at elevatad eemperature~.
Acld ~orm~ of zeolite~ can be prepared by a variety of technique~ including ammonium ex~nge ~ollowed by calcination, direct exchange of alkali ions fo~ protons u&ing mineral acid~ or ion exchan~arg, and by int~oduction of polyvalent ion~
r a di~uz~ion of acid 6ite~ in ~eol~e6, ~ee J.
Dwye~, UZeolite S~ructure. Compo6~tion and Cataly~i6"
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in Chemi6trY and Industry, April 2, 1984). The acid site~ produced are generally believed to be of the Bron~ted (p~oton donating) type or of the Lewi~
(electron pai~ accepting~ type. Bron~ted ~ite~ are generally produced by deammoniation at low ~empera~ures, exchanqe with protons, or hydroly~i6 of polyvalent cations. Lewi~ ~ite~ are believed to arise from dehydLoxylation of the H-xeolite~ or from the presence of polyvalent ion~. In the acidic zeoli~e catalygts of the pre~ent invention, Bron~ted 10 and/or Lewi~ ~ite~ can be pre~ent.
The c~y6~al ~t~ucture of zeolite rho i~
characterized by large cuboctahedral cages linked by douhle 8-ring6, defining pore opening~ of app~oximately 3.9 A by 5.1 A ~0.39 x 0.51 n~). One unu~ual characteri6tic of the 6tructure of zeolite rho i~ the presence of two independent 3-dimen~ionally-connected 6ystem~ of ~hannel6.
further unique 6~ructur~1 Eeature, described by Parise et al., J. PhYs. 5hem. ~8:1635 (1984) i~ a structural change occurring upon dehydration which re6ult6 in an inCLea~e in ellipticiey of ~he aforementioned 8-ring pore opening6. If a dehydrated ~ample of zeolite ~ho 1~ heated further, an increa~e in unit cell dimensions re~ult6, accompanied by a decrease in elliptici~y of the 8-ring pore opening~.
It ~hould be noted that catalytic 6electivity fo~ dimethylamine pro~ided by zeolite rho cannot be at~ribueed ~olely t~ it~ geometry. Other factors, for exa~ple, the number and nature of acid 30 ~ite6 on internal and external surface~, cry~alllte 6ize, external surface modifier~, and contaminant~
can al60 be expected to af~ect ~electivity for dimethylamine.

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For example, introduction of alkali metal or alkaline earth metal cation6 into th~e ~tructure of zeolite ~ho by ion exchange can alte~ the effective ~ize of channel~ and thus facilitate or hinder pa6~age of reactant or product molecule6 duLing a reaction. Thu6, cation exchange can be employed as a means of enhancing selectivity of 2eolite rho for dimethylamine.
A cciterion ba~ed upon empirical ob6ervation~ of zeolite ~orpeion characteri6tic~ ha6 been devi~ed in order to a~es~ the utili~y of variou~ ~mall-pore zeolite6 a~ catalys~ for conver~ion of methanol and ammonia to dimethylamine.
Thi~ c~iterion, which i6 hereîn denominated the geometric selectivity index ~or dimethylamine, or GSI, i6 defined a~ net solption of methanol (~eOH) divided by net ~orption of n-propanol (n-PrOH), each mea~ured a~ 25C following 20 hour6' expo~ure to sorbate vapor. Sorption i6 expre~sed in weight percent (gramE ~orbate per 100 gram~ ~eolite).
Sorption mea~urement~ are made using an apparatu~ sub6tantially analogou~ to that de~cribed by Landolt, Anal! Chem. 43:613 (19713. In a typical experiment, 0.4 ~o 1 g of zeolite i8 pre~6ed at 300-loOo p~i into a self-~upporting ~ylinder, in6erted in~o a pre-weighed sa~ple holder, evacuated, heated to 425C, cooled, and the~ weighed in the ~ample holder. The re6ulting ~ample i~ then expo~ed to ~orbate vapor at 10-50% o~ its vapo~ ~res6ure at 25C in a ~orption manifold, removed from the 60rption ~anifold, and weighed a~ain to determi~e ~o~tiO~ .
Small-pore zeoli~e~ other than zeoliSe H-rho demon~t~ate incr~a~ed ~ele~tivity for dime~hylamine with increased GSI . Su~pri6ingly, however, zeol~te H-rho doe~ not 6how ~uch a correlation. GSI observed for zeolite H-rho ~ample6 remain~ nearly cDn6tant with ~ignificant increa6e6 in selectivity.
Catal~st Preparat_ n Zeoli~e rho i6 ~ynthe~ized Ln a Na-C6 form ~ubstantially according ~o the procedurQ of Robson, U.S. Patent 3,904,738. In one met~od of preparing the H-form employed in the process of thi~ invention, Na~ and C~ ions are exchanged for NlH4+ ion6 and the re6ulting NH4~ form i~ deammoniated by calcination at 400C to 800~C. Although ion exchange of ammonium fo~ Na~ and C~+ ion~ may be incomplete in any given experiment, ~ypically leaving 0.5-1.0 C8 per unit cell, the produc~ of ion-exchange i~ ~efeered ~o he~ein a~ NH4-~ho. Similarly9 although deammoniation of NH~-rho may not re6ult in co~plete conver~ion o~
all NH4~ to H+ or other acid 6ites. pa~ticularly when a sample i6 calcined at lower temperature6, t~e resulting ploduct i6 ~efe~red to he~ein as "zeolite H-rho".
A form of zeolite H-rho containing very low level6 of re6idual C~ ion can be generated by treating zeolite H-rho with NaOH ~olution6 followed by exchanye with NH4+-ion containing solution6 and calcination. Repetition of the~e 6tep6 provide~ a form of zeolite H-rho with particularly enhanced ~electivity for dime~ylamine.
Identification of zeolite Na,Cfi-~ho i6 generally made by X-ray powder diff~action. The integra~ed in~ensitie~ of the ob6erved ~-ray pea~6 can be u~ed a~ a measure of zeolite cry~tall~nity.
High inten6itie~ indicate a highly cry~tallin~
p~oducts while low inten6tie~ indicate a le6~
c y~alline material. However, as cry6tallite size ~alls below about 50 nm, X-~ay dif~ractio~ peak6 broaden (H. P. Klug and ~. E. ~lexander, -Ra~

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Diffraction Techni~ue~, ~iley-Inter~cience. N.Y., 1974). When cry~tallite ~ize fall6 below about

2-6 nm, peak~ become ~o broad ~hat they are difficult to detect by conventional analog recording ~pectrometer~.
However, de6pite a lack sf mea6urable ~-~ay peak intensity, ~uch ~-ray amorphour~ zeolite crystallites are capable of ~hape 6elective cataly~
a~ recently reported by Jacob6 et al., J. Chemical Society, Chem;cal Com~unications, p. 591 (1981). For such crystallit0~, zeolite crystallinity i6 eYiden~
from infra-red ~pectra, so~ption mea~ure- ment6, and catalytic 6hape ~electivity. The acidic eho zeolite~
of the p~esen~ invention can be highly cry6talline, poorly crystalline, or ~-lay amorphous cry6tallite~.
Cation-exchanged forms o zeolite ~ho carl be prepared from a Na,Cs form of zeolite rho or from zeolite H-rho by contacting a cry6talline form of the zeolite with a solution containing the ion to he exchanged. Reeeated application~ of fresh ~olutions are nece~sary to obtain a significant degree of ca~ion exchange. A6 u6ed throughout the specific2tion, the term "zeolite Ca-rho" or "Ca-rho"
refer~ to a cation-exchan~ed ~orm of zeolite rho wherein the cation i6 Ca.
It is known (Rob60n, U.S. Patent 3,904,738;
Barrer et al., Proc. 5th Conf. on Zeolites, ~aple~, 1980, pp. 20-29) that ~mall amount6 o~ chabazite and pollucite impuritie6 are frequently found in r~o p~eparation6. It i~ believed that the~e impurities and small quantities of ce6idual gel are not ~elective to dimethylamine, and thus might reduce the selectivi~y to a ~e~cee dependent upon the quantity present in indi~idual sa~ple~.
1~ has previou~ly be~n e~tabli~hed ~K~
I'Hydrogen ~eolite Y, U}tra~table Zeolite Y, and .

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Aluminum-Deficien~ Zeolite~", in Molecular 5erie~, Advances in ChemistrY Se~ie& 121:210 (American Chemical Society 1973)) that WH4-zeolite~ deammoni-ated by deep-bed calcination techniques e~hibit propertie6 di~tinct from tho~e of zeolite~ deammoni-S ated by ~hallow-bed calcination technique6. Deep-bed calcination refe~ to combinations oiE bed geometry and calcination condition~, e.g., thick bed~ andJor ~low flow of ga~ over zeolite, which do not re~ult in rapid removal of gaseous H20 and NH3 from the heated zeolite. In contra~t, 6hallow-bed cal~ination rQfer6 ~o bed geometrie~ and condition~, e.g., ~hallow bed6 and rapid stripping of ga6e6 from the bed, uhich maximize removal of ~2 and N~3 f rom zeoli~.
The nature of the dif ference6 between a~id fo~m6 of zeolite rho a~ prepared by the above-described technique~ has not been pceci6ely pinpoin~ed. It ha~ been sugge~ted, however, that products of deep-bed calcination conditions contain nonframewor~ Al 6pecie6 which have di6sociated from the zeolite lattice ducing ~he deammoniation pcoce~6~ F~eude e~ al., Zeolite6 3:171 ~19~3) have 6hown that, according to temperature and the degree of deep-bed calcination of zeolite NH4-Y, n~nframework Al 6pecie~ contaîning octahedcally-~5 coordinated A1 are progre~6ively condensed.P-e~umably 6uch nonframework ~pecie~ function a6 catalytically active Bite6 OL as modifier6 of o~her catalytically-active ~ites. Conceivably, such highly-~onden~ed s~e~ies pre~ent following high-tempera~ure ~alcination are re6pon6ible fo~ the~ucpri~ingly high propoction of dimethylether produced over zeolite H-~ho cal~ined at hiqh temperature~ under deep-bed condi~ion6. AlternatiYe-ly, the high dimethyle~her yields might be caused by 1~

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othe~ catalytic ~ite6 produced ducing the dealumina-tion proce~ and the extLa lattice Al pha6e migh~ not be directly involYed. ~ illustca~ed by the ~xample~
set foLth below, the method of deammoniation ~ignificantly affect~ catalytic activity, and hence, product di~tribution, when acid fo~m6 of zeoli~e rho are employed a6 cataly6t~ in the reaction of ~ethanol and ammonia to produce mono-, di-, and trime~hylamine.
Clearly, a continuous gradation of calcina-tion condition~ can be azranged between extreme "deep-bed" conditions and extreme "shallow-bed~' conditions. Accordingly, def inition~ regarding ~uch condition6 are by necefiity ~omewhat arbi~rary, and various equivalent~ to the condition6 for calcination set forth helow can be a~ranged. However, the definition6 for calcination condition~ fiet forth Ln Table I. below, apply throughout the ~pecification.

T e I: CatalY6t Calcination Condition6 Bed T~pe Qua6i-Shallow-Bed Deep-Bed Dee~=@~
Bed Thickness < 3 ~ 3 ~ 3 (mm) Gas Flow Rapid or continuou~ Same afi Little or Condition6 gas flow, vacuum 6hallow- no ga~ flow ga6 removal, or bed during cal-fluidi~ed bed con- calcina- cination ditions maintained tion du~ing calcination

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Te~pera~ure ~00-750 400-800 $00-6~0 (C) ~prefe~red:
~educed DMæ
60a-7so production) ~prefec~ed) (grea~er ~ME
production~
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In general, zeolite H-cho exhibi~6 greater ~electivity to dimethylamine when ~he NH~-f orm i~
calcined at higher temperatures and/or fcr lo~ger time6. Increac~ed deammonication temperatures appear to be more effe~tive than increa6ed calcination S periods for increasing selectivity ~o dimethylamine.
However, deep-bed calcination6 at high temp~rature6 ~>650C) can re~ult in a catalyst with higher level6 of dimethylether (DME) production than tho~e at lower temperature6. Use of cataly6e6 prepared under shallow-bed conditions generally result6 in lower level~ of D~E p~oduction.
Generally. calcination temperature6 ~ust be 6ufficiently high to convert 6ubstantially all NH4~
~ites to H+ 6i~e~ and o~her acid 6ite~, yet no~ high enough ~o render 6ignificant amount6 of ~he zeolite amorphou6. The pre6ence o~ NH4~ in a qiven 6ample can be determined by infrared measurement6.
Exce~6ive cal~ination can lead to ~ollapse of zeolite cry~talline structure and an a~orphou6 state, which i~ to be distinguî6hed from the "X-ray amorphous"
zeolitic material~ de~cribed abo~e. The "X-ray amorphou6~ zeolite~ are obtained by limiting cry~tallization time6, ~o that very ~all zeoli~e ~rystallites r~6ult. The~e crystallite~ exhibit charac~eri~tic zeolite 6ele~tivity, but pe~mit rapid ingce~ of reactant molecule6 and egre6s of product ~olecule~ Bue to their 6mall ~ize.
~ here deep-bed condition6 are employed and DME production 15 undesi~able, calcination temperature~ of about 500 to 650C are prefe~red~ If D~E production can be tolerated, the upper limit for calcination temperature can be extended to abou~
800~C. Under ~hallo~-be~ ~onditionfi~ calclnation temperature6 of abou~ 400 to 750C ~an be ~mployed.
Temperature~ of 60Q-750C are p~eferred~

Proce~s Condition~
As p~eviou61y noted, the proce~ of the pce6ent invention compri~es reacting methanol and/o~
dimethylether (DME) and ammonia, in ,amounts ~ufficient to provide a carbon/nit~ogen (C/N) ratio from about 0.2 to about 1.5, at a temperature ~rom about 250C to about 450C, in the pre6ence of a catalytic amount of an acidic zeolite rho, of which zeolite6 ~-rho and Ca-rho are examples. Rea~tion pressure~ can be varied from 1-1000 p~i (7-7000 kPa) with a methanol/DMæ ~pace time of 0.~} to 80 hour6.
The re6ulting conversion of me~hanol and/or DME to methylamine~ i6 generally in exce~6 of 85~ (on a ~ole ba6i6) and 6electivity (on a ~ole ba~i6~ to dimethylamine i~ generally greater than 4Q~. In addition, selectivity to and yield of trimethylamine i~ ~uppres~ed. Thu6, molar yield6 of dimethylamine geneeally exceed 40~ and molar yield~ of trimethylamine generally are les6 than 30% under the proce6~ conditions of the present in~ention.
The proce~ variable~ to be monitored in pcacticing the p~oce6~ ~f ~he p~esent inventio~
in~lude C~N ratio, temperature, pres~ure, and me~hanol/DME ~pa~e ti~e. The latter variable i6 calculated a6 ca~alyst ma~ divided by the ma66 flow rate of ~ethanol and DME introdu~ed to ~ proce6~
ceactor, (ma~6 cataly6t~ma6~ methanol~DME fed per hour).
Gen~rally, if proce~ tempe~ature6 ace too low, ~educed conversion of reactant6 to dimethylamine will re6ult. On the other hand, if temperatures are : exce~6ively high, equilibrium con~er~ion~ and cataly6t deac~ivation ~an oc~ur. P~ef~lably, temperatures are maintained between about 300C and about 400C, with lower ~emperature~ withi~ thi6 : 35 :::
~ : ~7 lB
range especially pre~elced in ocder to minimize cataly6t deactivation. At rela~ively lo~ pre6~e~, product~ must be refrigerated to conden6e them for fur~her purification, adding ~o~t to ~he ove~all ~roce~. However, exces6ively high pre~ure6 require co~tly thick-walled reaction ve~6el~. Prefer~ed pces~ure range from 10-500 psi [70-3000 kPa~. Short ~ethanol/DMæ 6pace times re~ult in low conver~ion6 and tend to favor the production of monomethylamine.
Long methanol/DME 6pace time~ may re~ult eithe~ in inefficient use of catalyst or p~oduetion of an equilibrium di~tribution of ~e~hylamine~ at very high conversion~. Generally, methanol~DMæ ~pace ~imes of 0.01-80 hourfi are satisfactory, with methanol/D~E
space time6 of 0.10-1.5 hour~ being preferred (corre~ponding to methanol/D~E ~pace velocitie6 of O.013-100 g msthanol+VMEtg catalyst/hou~, prefecably O.67-10 g met~anol~DME/g cat.alyfit/hour).
The eeactant ~atio of methanol ~nd~or DME to ammonia, her2in expre~ed a~ the C~N ratio (g ~toms C/g atom~ N), i6 c~itical to the process of the pre~en~ invention. A~ the C/N ratio i~ deccea6ed, production of monomethyl~mine i6 increa6ed. Az the C/N ~atio i6 increa~ed, produceion of trimethylamine increases. Cataly6t deactivation i6 al60 greater at high C/N ratios. Accordingly, for be6~ result6, C~N
~atio~ ~hould be maintained between 0.2 to 1.5, and preferably from 0.5 ~o 1.2 in condueting the p~oce of the p~e~ent invention.
The efficie~cy of the proces6 of the inven-~ion i6 measured by overall conve~sion of methanoland/~r DMæ to methylamines, and by ~electivity of dimet~ylamine production. For example, if ~ethanol i8 u~ed az the 801e reactant, overall conver~ion i6 ~e~e~mined by ~omparison of the amoun~ ~in mole~) of 3s lB
;, :

methanol in the pr~duct mixture, which i6 con6idered to be unconverted, to ~he amount in tAe leactant feed.
Thus, ove~all conversion, in percent, i~ given by:

100 (1 Mol~s ~eOH i~ produ~t) Moles ~eOH in ~eed Conve~ion of methanol to methylamines, in percent, is given by:

10o /1_Moles ~eOH in product f 2(Moles DME in Product)) ~ ~ole6 ~eOH in feed Conver~ion of methanol to monomethylamine (MMA) in percent, is given by:

100 ~ MGle6 MMA
~ Mole~ MeOH i~ ~eed J
Similarly, conver6ion of methanol to dimeehylamine (DMA), in percent, is given by:

lQO ~ 2(~oles DMA~ ) ~ Mole~ MeOH in feed and converfiion of methanol to trimethylamine (TMA), in percent, is given by:

loo / 3 (Moles T~A~ ~
~Mole~ MeOH in feed Finally, ~eles~ivity to DMA is calculated by analysi6 of p~oduct compo6ition. Thu6, B*lectivity ~o VMA, in 30 percent, i6 provided by the following expre~6ion:

100 l ~
~ ~MMA~ ~ 2[DMA] + 3[TM~] /

, ~

6~

For efficient operation, the cataly~t mu~t be ~elec~ive at high conve~6ion~ (87-98%) and a CiN
ra~io of 0.5-1.2.
In practicing the proce~ of the invention, the zeolite cataly~t can be combined wi~h another mate~îal re~i~tant to the tempe~ature and other condition~ employed in the p~oce~. Such mat~ix materials include synthstic or natural ~ub~tan~es fiuch a~ clay~, silica, and me~al oxides.
Comparion of 6electivitie~ for different ~ample6 ~hould be made at ~imilar conver6ion~, since ~electivity change~ with conver~ion. At low ~onver-sion~, ~MA production i~ favored; at ve~y high conver6ion~, the reaction will approach an equilib~ium di~tribution and thus ~e6ult in inc~ea6ed TM~
p~oduction.
The proces6 of the pre6ent invention can be furthe~ unde~6tood by refe~ence to the following Exam~le~, wherein all temperature~ are expre~sed in degree6 Cel6ius (C) and all percentage~ are by Zo weight unle6~ othelwi~e indicated. In compo~ition determination~, it wa~ a66umed that there were 96 oxygen atom~ per unit cell. Analy~i6 determined the ~ela~ive amount~ of the variou~ cation6 pre6ent, and remaining positively-charged ~pecie6 were a~fiumed to be hydrogen.
E~MPLE 1 A Ra~ple oS zeolite H-~ho, whieh was employed a~ catalys~ in this Example and Example 2, below, wa~ prepared as follow~. A mixture having the compo6i~ion 2.80 Na20- 0.5 C~20 ~A1203 ~11.1 Si02-120 H20 was formed by adding gO m~ 4 ~
Na2A1020H, 31. 5 ~L 5 . 79 N C60H, and 13 g NaO~ to 355 ~L eollsidal ~ilica ~Ludox~ LS-30~ in a polypropylene ~onta~er. ~he re~ulting mixture wa~ allowed ~o ~tand a~ 25 for~ days, and ehe~ h~a~ed ~2~6~

at 100 for 10 day~. The re~ulting product wa~
washed sevecal time6 and then allowed to ~tand in contact with a 23~ NH4N03 ~olution fo~ about 65 hour~
to p~oduce NH4-rho. Thi~ material wa6 then convected to ~-cho by calcinaeion at 415~ in aic for about 16 hour~ unde~ deep-bed co~dition~. Analy~ f the re~ulting zample of zeolite H-rho indicaeed it~
compo~ition to be C~0 7~a0~2Hlo~22Al~ ssi367~4os6 Two g~ams of thi~ p~epa~ation of zeolite H-rho were placed in a ~tainles~-~telel U-tube reactoc 0.12~ in (0.55 cm) in diameter and about 12 in (30 cm) in length. The reactor ~a~ heatled ~o reaction temperature in a fluidized ~and bath. Thi6 experiment and that reported in Example 2, below, were conducted at atmo~pheric pre6~ure (14.7 lS lb6-in 2, 101 kPa). Reactant6 methanol and ammonia wece fed to a preheater a~ a liquid ~ixture at a molar ratio of about 1, vaporized, and then pa6sed th~ouqh the Leacto~ into contact with the cataly6t.
Reaction temperatur~ and reactant flow rate~ are shown in Table II, below.
The ceactor effluen~ wa~ analyzed by gas chromatog~aphy for ammonia, dimethylether (DME), methanol, water, and mono-, di-, and tri~ethylamine.
The pe~cen~age conve~ion~ of ~ethanol (overall), of methanol to methylamine6 (MA), and the percentage 6electivitie~ of conve~6ion to each me~hylamine specie~ a~e given in Table II, below. That portion o~ methanol convected eo other than methylamine6 wa6 converted to DM2 in ~hi6 and all other Examples reported herein.
EX~MPLE_2 A portion o~ ~he zeolite H-rho preparation de6cribed in Example 1, above, was heated in flowing N2 at 5Q0~ for 2 hc~ under qua~i-deep-bed .
~ 21 i~

:. .. . . .

:~f~

calcination conditiong. 2 g of this material were placed in a reactor and employed in a catalyst evaluation experiment conducted ~ub61:antially similarly to that reported in Example l. The re6ult~
of thi~ experiment are set forth in T2ble II, below:

Table IIo U6e of Zeolite H-rho as Catalyst for Dimeth~lamine Synthesi6 ~eOH- Selectivity Calcination Reactor _ MeOH MA (~) Ex~ T Time T Feed Flow Conv. Conv.
10 ample (C) (hr) (C~ (mL/hr) tS~ MMA DMA TMA
l ~15 l~ 350 12 85 79 16 3~ 48 E~MPLES 3-ll The result6 of Exameles 3 through ll, which are ~et forth in Table III, below, illustrate the celationshie between selacti~ity to methylamine products and ~eed flow rate and pres~ure. DMA yield~
in exce~ of 40% at a C/N ratio of l were obtained in 2 each of Examples ~-ll. The zeolite H-rho amployed a6 cataly~t in the6e examples wa~ p~epared by the following procedur~:
A mixture of 200 mL 4 M Na2AlO2OH, 56 mL 50 C~OH, and 26 g NaOH wa~ added to 720 mL of colloidal 2 silica (Ludox~ LS-30) in a polytetrafluoloethylene (Teflon~ bottle, and permitted to ~tand at 25~ for 9 days. The re6ulting mixt~re was then heated at l00 for 7 day~, allowed to stand at 25 for a~ additional 3 day6, and then reheated to lOO for 2q hr~. $he re6ulting product wa6 then washed and contacted overnight 3 ~ime6 ~ith a 20% NH4NO3 ~olution. The ~e~ulting prepara~ion of zeolite N~4-rho indicated a formula upon analy~i~
(NH~)9.6C~ 0.3si37 796 q2-9 ~zO-, ~

~2~ 2 A po~tion of this material was converted to H-lho by calcination at 550 in air for 18 h~ under deep-bed condition~.
The cataly~ evaluation expe~iments of E~amples 3-11, which are reported in. Table III, were conducted ~ub~tantially ~imilarly to Example 1, above. Examples 3-11 demon~t~ate that higher flows and lower methanol conver~ions increa~e ~electivity to ~A and decrea~e ~electivity to TMAt In addi~ion, Example~ 3-11 indicate ~hat increa6ed reactor pre~sure inc~ea~es ~elec~iYity to DMA a~d decrea~e6 ~electivity tD TMA when compared at ~imilar methanol conversion6.
Table III: Effect of Feed Flow Rate and Pre~ure on H-~ho Selectivity for Dimethylamine MeOH- Selec~ivity Feed MeOH ~A ~) Ex- Pres~ure T Flow Conv. Conv.
amPle ~ %C~ (mL/hr) (t~MMA DMA TMA
3 14.7/101 3001& S7 65 31 5713

4 14.7/101 30012 ~O 78 23 ~016 20 5 14.7/101 300 ~ ~6 ~ 21 ~020 6 14.7~1~1 300 6 92 ~0 18 ~022 7 14.7~101 ~OO 4 98 9~ 16 5925 9 12~/830 30032 ~6 ~5 lg 6812 11 120/830 300 8 9~ 97 15 6322 Example~ 12-19 illu6t~ate the effect~ of high deep-bad calcination te~p~ratures and extended calcination time~ upon s~lectivity to DMA ~4r H-rho ~: zeolite~. In genelal, in~rea~ing calcinaeion temperatures and lengthening calcination times inc~ea e electivity to D~A, but al~o increa6e conve~ion of methanoI eo dimethyleth~r ~DM~).

;

, Each sample of zeolite ~-rho evalua~ed in Examples 12-15 was evaluated for sorp~ion of methanol and n-propanol. The following procedure wa~ employed:
Each ~ample ~as placed into a preweighed cell and evacua~ed. The sample wa~ slowly heated to 425 under vacuum and held at 4Z50 for 18 hr6. Af~er expo6ing the ~ample to 375 mm oz ~or ~0 minutes to burn off any oryanic ma~erial, the sample was evacuated at 425 until the pressure ~eached 3.7 ~ -10 5 mm Hg ~.9 x 10 3 Pa). A~ this point, the sample was weighed. The sample was then expo~ed to 38 mm methanol vapor for ~0 hr~e and then weighed again to deter~ine the amount of methanol that had been sorbed. The methanol ~oebed per 100 g zeolite could then be calculated. Subtraction of 0.37 g ~eOH/100 g zeolite ab60~bed on the external 6urface o the zeolite yielded the sorption values indica~ed in Table IV, below. Quanti~ies of n-propanol sorbed were determined in a 6i~ilar mannec. Table I~ li8~6 the amount of methanol and n-propanol sorbed for each of the rho zeolite6 and the GSI calculated from these measurement~. De~pite the laLge increase in selectivity to DMA with increa6ing calcination temperature, GSI values remain low and essentially constant. ~his higher ~electivity to D~A, at essentially constant GSI, could ari~e from non-geometric ~actors induced or enhanced by calcination at progre6sively higher temperatures, or from geometric factors present at reaction conditions but ~ot at the conditions at which GSI measurement6 are made, or from a co~bination of these effects.

~5 .:~

~able IV: Effect of Calcination ~empera~ure Upon Geome~ic Selectivity Indices ~GSI~
of Selected Sample~ of Zeoli~e H-Rho al~ination Sorption Temp. Timefq/100 q zeolite) Exam~le(C) (hr) MeOH n-PrOH GSI
12 450 65 24.7 ~0.6 1.2 13 5~0 1~ 20.2 13.~ 1.5 14 625 2 18.6 15.4 1.2 725 2 20.Z 16.6 l.Z

~E~CAMPI,E 12 For this exampleO ~eolite H-rho ~as prepaced by a modifi~ation of ~he general procedure de~cribed in aobson, U.S. Patent 3,904~738. Three sepa~ate ~ample~ of Na,Cs-rho were prepa~ed by combining 100 mL 4 M Na2AlO2OH. 16 g ~aOH, and 27.7 mL S0~ C~OH
with 357 mL colloidal SiO2 (Ludox~ L5-30) in a 500 mL
polypropylene bottle. The re~ul~ing mixture wa6 permi~ted to 6tand at 25 fo~ 6 day6, and then heated on a 6team b~th ~or 3 days at ~2-93. The cesulting produc~ we~e then filtered, d~ied, and contacted with 23~ NH4NO3 at 90 for 65 hour~. An ~-ray difraction paStecn disclo ed the presence of zeolite NH4-rho and a trace of a chabazite-li~e impurity.
Each of the 6a~ple~ wa6 heated under deep-bed condition6 at 400 in air for 2 day~. ~wo of the three ~ample~ were combined and con~acted with 20%
NH~NO3 at 100 for 2 day~,. After filtering, ~a~hing, and drying, the sample wa6 calcined again unde~
deep-bed condition~ at 450 for 65 hr6, coo].ed. and the resulting zeol~te H-rho ~valuated afi a cataly~t 6ub~tantially accordinq to the procedure de~cribed in Example 1, above. The re~ult6 are set for~h in ~ ~able ~, below.
: : :

,:

::~2~6~
~6 A mix~ure of 200 mL ~ M Na2A1020~, 56 mL 50%
C~OH, and 26 g ~aOH was added to 720 mL of colloidal 6ilica (Ludo~ LS-30~ in a poly~et~afluoro- ethylene (Teflon~) bo~tle. The re~ulting preparation was 4 5 allowed to stand for 7 day~ at 25 and ~hen for 1 days at 90. A ~o~tion of the re~ulting zeolîte ~aOC~-rho was cvntacted ~wice for 16 hr~ with a 20%
NH4N03 ~olu~ion at 80 ~o produce zeolite NH4-rho.
Zeolite H-rho wa~ prepared by heating the zeolite NH4-rho under deep-bed ~ondition6 in air at 250 for 1 hr and then at 500 foc 16 hr6. 2 g of the re~ulting ~ataly~t ~a~ evaluated sub~tantially according ~o the procedure o~ Example 1. The re6ul~8 of thi6 experiment are set forth in Table V.
EX~MPLES 14 and 15 200 mL 4 ~ Na2A1020H, 56 mL 50% C60H, and Z6 g NaOH were added to 720 mL colloidal silica (Ludox~
LS-30) in a polytetrafluoroethylene bottle, and permitted ~o ~tand for 12 day~ at 25. The re6ulting mixture was then heated for 7 day6 at gO, ~hen contacted twice with 20~ NH4N03 at 80, for about lB
h~6 each ~ime, to pcoduce zeolite NH4-rho. ~hi~
material was then calcined under deep-bed condition~
in air at 465 for 16 hr6, follo~ed by 30 minu~e~ at 600~. The re~ul~ing preparation wa~ divided into ~wo ~ample6. A first sample, employed in Example 14, wa~
heated for an additional t~o hour~ at 625. The other ~ample. evaluated in Example 15, wa~ heated for two hour6 at 725. In 6eparate experiments, 2 g of each 6ampIe were evaluated in a research reactor ~ubstantially as de6cribed in Example 1. The re6ult~
of Example~ 14 and 1~ are ~et for~h in Table V, below.

~: 35 ~
i ~24~

E~AMPLE 16 Zeolite Na,C~-rho was prepared according to the following procedure. A mixture of 800 mL of 4 Na2A10zOH, 224 mL of 50~ C~OH, and 104 g NaO~ wa~
added to 2B80 mL of colloidal SiO2 (Ludox LS-30~) in a Teflon~ bottle and allowed to ~tand at 25C ~or 11 days. The mixture was heated at 100C for 9 day6.
The product ~Na,C~-rho) wag washed and dried at 110C. Thi~ Na,Cs-rho, after washing and filtering, wag contacted four time~ with a 20% NH4N03 ~olution at ~90C with filte~ing between each exchange~ to produce NH4-rho.
Zeolite H-rho wa~ prepared by heating 5 g of N~4-rho for 1 hr undar deep-bed condi~ions in air at 800. After cooling, the sample ~as pre6sed in~o a wafer. cru6hed, granulated and 6craened.
In an experiment sub~tantially ~imilar to that described in Example 1, methanol and ammonia were pa~6ed over a cataly6t consi6ting of Z g of thi~
preparation of ~eolite ~-rho, in the form of ~ 20-40 me6h powde~. The condition~ employed and result6 obtained are ~hown in ~able V.
EX~MPLE 17 Zeolite H-rho was prepared by heating 4 g of the powdered zeolite NH4-rho pcepared in Example 16 for two weekg undeL deep-bed condition6 in air at 550. The weight lo~ during thi~ thermal treatment wag 19.5~. The~product was zeolite H-rho.
I~ a pro~edure 6ub6tantially the same a6 that described in ~xample 1, methanol and ammonia ware pa~ed over a ca~aly6t consi~ting of 2 g of the zeolite ~-rho. The condition6 employed and re6ults obtainad are shown in Table V.

2'7 .:,, , 2~
EXAMPLE lB
Zeolite H-rho wa~ prepared as follow~. A
mixture of 200 mL 4 M Na2~1O2OH, 32 q NaOH, and 56 mL
50% CsOH ~a6 added to 720 mL of colloidal ~ilica (Ludox~ LS-30) and allowed to ztand at room

5 temperature for 6 days. Thi~ mixture wa~ heated to 100~ for 6 days. The re~ulting product (Na,Cs-rho) wa~ filtered. wa6hed ~ith distilled water, and dried. This procedure wa~ repeated and the dried products of both batche6 combined. A 50 g ~ample of the combined Na,C~-rho product wa~ contacted witb 50 mL of a 10~ NH4NO3 ~olution th~ee times at 90 for 1 hr ea~h. After thorough washing with di6tilled water, the ~ample (WH4-rho) wa~ dried at 110.
por~ion of the dried NH4-rho wa~ then calcined under deep-bed condition6 by rai~ing ~he temperature 50~
per hr to 550 and then heating the fiample at 550 ~or 10 hr~ to give H-rho. The result~ of the evaluation of thi6 material, which wa6 conducted sub6~antially a~ de6cribed in Example 1, are ~et forth in Table V.
EXAMPL~: 1 9 Zeolite NH4-rho was p~epaced ~ub~tantially a6 desccibed in Example 16.
Zeolite H-rho wa6 prepared by slowly heating 250 g of the zeolite NH4-rho under deep-bed : conditions, in a slow ~ream of air. flom room temperature to 550 in 30 minute~. ~he tempecature wa~ then held at 550 for 3 hrs. The ~ample was then allowed to cool to 100, tcan~fe~red to a tared jar, ~ealed, allowed to cool to room temperature, and then weighed. The weight of the calcined sample wa~
223 g~ cocre6ponAing ~o a weighS lo~ o~ abouC 9~O
Chemical analy~i6 ~howed that the sample contained, ~y weight, 3.3% CB, 9~ ~1, and 160 ppm Na~ The - 3S prod~cS wa~ zeoli:te H-~ho.

.:
: : ., ~ H4-~ho was prepared by contacting ~50 g of the re~ulting produc~ H-rho with 1500 mL of a 10~
NH4N03 ~olution at 90 ~hre~ time6 for 1 hour each.
After thorough wa~hing with di~tilled water, the ~ample wa6 dried at 110. The re~ulting NH4-rho ~a~
calcined by raising the temperature 50 per hr ~o a final temperature of 700 and ~eating th~ 6ample at 700 for 10 hrs to give H-rho. ~hi6 material wa~
evaluated ~ubstantially as de~cribed in Example 1, and the re~ult6 are se~ forth in Table V, below.

The re~ult~ of Example6 20-Z3 demon6t.rate ~ha~ ~hallow-bed calcination technique6 provide ~-rho zeolite catalysts ~i~h exceptionally high 6electivities to DMA.
Por~ion6 of the 6ample of N~14-rho prepared in Example~ 3-11 were converted to H-rho by a 6hallow-bed calcination technique. A ~ample con6i6ting of 5.0 g of UH4-eho wa6 6pread out in an A1203 boat, pa66ed into the hot zone of a belt furnace at 0.64 cm/mlnute, and held at 400 for 27 hr6 under a N2 f low of 20 L~in. An infra-red spectrum indicated, from the ab6ence of an ab~orption band at 1400 cm 1, that sub6tantially all NH4~ ions had decompo~ed, giving H-~ho containing e6sentially no NH4 . A 6eries of ~ample6 were prepared by this 6hallow-bed calcination te~hnique at different temperatures under the condieions indicated i~
Table VI. Each 6ample was evaluated 6ub6tantially 30 according to the proceduce of Example 1. ae6ult6 are 6et forth in ~able Vl, below.

:
~5 Table V: Eff ect of Deep-Bed Calcination~ Upon Selectivity of Zeolite H-rho for Methylamine~
Calcina- Reaction ~eOH- MeOH- Selec~ivi~y tion Feed MA DM~ (t) ~x- T Time T Flow Conv. Conv.
amPle (CL (hr) (~C) (mL/h~ %) UMA DMA TMA
12 45065 300 4 95 l l9 31 50 13 500l~ 300 8 88 l 20 ~9 41 14 625 2 300 8 ~8 l Z~ 47 31 16 800 l 300 4 64 25 17 73 l~

l~ 550 lO 300 ~ 87.4 2.6 13 50 37 19 770 lO 300 6 74 ll 21 6~ 16 Table VI: Effect of Shallow-Bed Calcinations Upo lS Selectivit~ of Zeolite H-rho for MethYlamine~
Calcina- ~Reaction MeOH- MeOH- Selectivity tion Feed M~ DME . (~) _ Ex- T Time r Flow Con~. Conv.
amPle (C~ (hr) (C) (mL~hr~ S%~ ~MA DMA TMA
40027 328 3 88.3 4.7 14 5432 21 50016 325 3 84.7 4.3 16 ~024 2~ 600 4 300 2 ~3 7 16 7~8 23 700 4 325 Z 87.3 6.7 15 7~ll EX~MPL~S 24-27 Example~ 24-27 illu~trate the enhancement of dimethylamine ~electivity provided when zeolite H-rho i~ trea~ed with NaOH, further exchanged with NH4N03 ~olution, and then calc;ned.
EXA~PLES 24 and 25 : Zeolite H-rho wa~ prepared by heating a por~ion of the NH4-Lho prepared in Example~ 3-ll at : 545 in air ~or 6 hr6. Analy~i~ indica~ed that ehe p oduct zeolite H-cho had the compo~ition : : 35 . ~ .

Hl0.0C80.8Allo 8Si37.296'54 H2O- A portion of thi~
material wa~ ~e6erved for evaluation a~ Example 24.
Another portion of the zeolite H-rho was ~lurried at 25 for 14 hour~ wi~h 500 mL of lN NaOH
~olution ~o prepare Na-rho. Thi~ ~lurry w~s filtered, wa~hed thoroughly, and exchanged twice with 500 mL of a 20~ NH4NO3 ~olution. Aftar fllt~ation, washing and drying, ~he re~ulting mat:erial wa~
calcined for 6 houL~ in air a~ 550. Thi~ two tage proce~s (61urcying with lN NaOH. recovery and ~esluerying twice with 20~ N~4NO3) wafi then repeated. After a final calcination at ~50~ for 6 hou~, the product wa~ analyzed, indicating the following composition:
Hg,02CS0.04(NH4)0,0l 9.08 38.92 96 Z
In a procedure ~ubs~antially the sa~e as that de~cribed in Example 1. methanol and ammonia we~e pas~ed ovec a cataly~t con~i~ting of 2 g of the zeolite H-~ho of Example 24 and 2 g of the zeolite H-~ho of Example 25. The condi~ion6 employed and re~ult~ obtained are 6hown i~ Table VII.
E~MPLES 26 and 27 Zeolite E~-rho wa6 prepared as follow~. A
~ixture of 400 mL 4 M NazAlO2OH, llZ mL 50~ C~OH, and

6~ g ~aOH wa~ added to 1440 mL of colloidal ~ilica (Ludox~ LS-30) ~n a polytetrafluoroethylene container, and allowed to stand 6 day~ at 25. The re~ulting material was then hea~ed at 100 until crystalline, a~ dete~mined by powde~ X-ray dif~raction. The re~ultin~ product wa~ filta~ed, wa~hed and dried at 110. The foregoing procedure wa~ 6ubstantially repeated fo~ a ~econd ba~ch, which wa6 combined ~ith the product o~ the fir6t batch.
750 g o the combined product~ were contacted three "

i6~

~ 2 times, for one hour each time, wi~h 7500 mL of a 10 NH~N03 601ution at 90 to produce zeolite NH4-rho.
Zeolite ~I-rho wa6 pLepared by calcining thi~ m~telial unde~ deep-bed ~onditions~ in ai~, by raising the calcination temperatu~e 60 per hour to 550, and then holding the sample at 5500 for 10 hours.
~ample of this material wa~ re6erved for evaluation a~ Example 26.
300 g of the zeolite H-rho prepared above were sti~ed in 750 mL 1 N NaOH for 24 hour~. ~he treated zeolite was then filtered, wa~hed with di~tilled water and methanol~ ~nd then d~ied a~
110. The dried zeolite wa~ then 61urried in 10~
NH4N03 three time~, f Ol one hour each ~ime. at 90.
After thorough wa~hing again with water and ~ethanol, the ~ample was again dried at 110. The ee~ulting ~aterial wa~ then calcined in air by rai6ing the temperature 60 per hour ~o a final temperature of 550 and heating the matec~al at 550 or 10 hour6.
The entice proceduce de~cri~ed above was then ZO repeated. The re~ulting ~aterial wa5 given the de~ignation "NaOH-treated H-rh~'`.
U6ing a procedure ~ubstantially similar to that de~cribed in ~xample 1, methanol and ammonia were con~acted with 2 g of ~he H-rho prepa~ed a~
Example 26 and 2 g of the MaOH-treated H-rho prepared a~ Example 27. The ce~ult~ are 6et forth in Table VII, below.
The lower DMA 6electivitie6 of Example~ 26 and 27 are believed to result rom the pre~ence of amorphous contaminant~.

` 3Z

6~

Table VII: ~:ffect of NaOH Peecalcination Treatment Upon Dimethylamine Selectivit~ of Zeolite H-Rho MeO~-Reaction _ MeOH ~ Selecti~ity Temp. Flow Conv. Conv. _ ~%) Exa~Ple ~C) ~mL/hr) (%2 ~ ~A D~A TUA

30~6 ~9 ~ 20 73 7 26 3004 9~ 91 11 3~53 27 3004 ~4 91 15 55~9 E~AMPLES ?8 and ~9 Example6 28 and 29 demonst~ate the ~ele~tivity to dimethylamine of zeolite H-rho and zeolite Ca-~ho.
To prepare cation-exchanged sample6 of zeolite H-rho, a mixture of 270 mL 4 M Na2A1020H, 74.B ~L 50% CsOH, and 43.2 g NaOH wa~ added to 9fi4 mL
colloidal si}ica (Ludox~ L~-30) in a polytetrafllloro-ethylene bottle and allowed to stand for 6 day~ at 25o followed by 3 day6 a~ 100. The re6ulting 20 Na,C~-rho wa~ then exchanged ~wice (48 hour~ and 95 hou~s) with 20~ NH4N03 a~ 90 to produce NH~-rho.
Zeolite H-rho wa~ prepared from ~e re~ulting NH4-~ho by heating in air at 450 fol 16 hour~ Some of Shi~
~_rho wa~ evaluated as Example 2~.
To p~epare Ca-~ho for evaluation a6 Example 29, a portion of the H-rho p~epared above wa~
slu~ried with 0.6 g of Ca(OH)2 in 200 mL H20 at Z5 fo~ 6 day~. The re~ulting pLoduct, de~ignated Ca-~ho, exhibited a Ca/Al ratio of 1.23. A
30 non-zeoli~e Ca-~on~aining phase ~ay also have been pce~ent.
~ ach of the ~ample~ prepared above W26 evaluaeed for dimethyla~ine ~electivity and catalytic : 33 , .

performance 6ubstantially according to the procedure of Example 1. ~he lesult~ and condition~ of Example~
2B and 29 are ~et forth in Table VIII, below.

Table VIII: Effect6 of Cation Exchange Upon _ Selectivity of Zeolite H-rho ~eOH-Feed HeOH H~ Selectivity Zeolite Temp. Flow Conv. Conv. ~%2 Exam~le Catalyst (C) (mL/~r~ (%~ ~%~ MMA DMA ~MA
28 H-rho 300 5 91 89 12 45 43 29 Ca-rho ~50 2 94 89 16 51 33 COMPARA~IVE E~PERIME~TS A -_E
Comparative Experi~ent6 A - E demon6tra~e that certain zeolite~ having pOlt6 bounded by 8 aluminosili~ate tetrahedra, for examp}e~ erionite, and zeolites having port6 bounded by }O or ~2 alumino~ilicAte tetralledra, fo~ example, ferrierite, silicalite, and zeolite Y, displ~y little or no selectivity to dimethy~amine when compared to the 20 value~ attained at equilibrium for the uncatalyzed reaction of methanol and ammonia. Similar re~ults are ob~aihed when a~ alumina-6ilica ca~aly~ (91 Alz03, 6.5% SiO2) is employed. Compari~on of the re6ult6 of Comparati~e Experiment~ A, B, C and E witb ~5 example~ of ~he invention conducted at si~ilar flow rate~ ~ugge~ that comparable conver6ion~ can be obtained wi~h acidic zeolite rhQ at tempera~ure~ 100 belo~ tho~e employed in the Comparative Experiments.
COM2ARATIVE E~PERI~ENT A
~eolite H-ferrierite wa6 prepared ~y heating a 6ample of ~errierite t2eolon~ 700, Norton Co~pany) to 500 in flowing ~2 o~ ~0 hour6 and the~
contacti~g ~he resulting sample three time~, ~or one : hour each time, with a 10~ NH~03 solutio~ at ::
: 34 . ~

~ 5 ~0~. The re~ul~ing material w~6 dried and heated by increa~ing the temperature 50 per hou~ ~o 500O and then ~eld at 500 for ten houE60 The ~esulting sample of H-fe~rierite wa~ ~hen cooled and evalu~ed for dimethyla~ine ~electivi~y by ~ procedure 6ubstan~ially similar to t~a~ de~cribed in Example 1. The condi~ion~ employed and ~he resul~
obtained are ~et forth in Table I~, belGw.
COMPARATIVE EXPERIMENT B
Zeolite H-erionite wa~ prepared ~rom a sampl~ o zeolite N~4-erionite ~Linde* E~10) by a procedure sub~tantially 6imilar to that de~cribed fol prepara~ion of H-fe~rieri~e in Comparative Experiment A. The re~ul~ing material wa~ evaluated for dimethylamine selectivity ~ub~tantially according to 15 the procedure of Example 1. The re~ult~ obta~ned are 6et forth i.n Table 1~, below.
COMPARATIVE EXPERIME~T C
Methanol and ammonia were pas~ed ove~ a cataly6t con~ifiting of 2 g of zeolite ~I-silical:ite (S-ll~. Union Carbide Corporation~ substantially as de~cribed in Example 1. The condition~ and re6ult6 are di~played in Ta~le I~. Thi8 material 60rbed 12.5 g methanol and 12 . 5 g n-propanol per 100 g ~ataly6t, proYiding a GSI of 1.
Z5 COMP~RATIVE E~PERIMENT D
100 g of zeolite NH4-Y (Linde LZY-82) wa~
calcined in air by heating in 50 6tepwise increment~
to 545, and ~hen held at 5~0 or about 10 hour6.
The ~esulting product, zeolite H-Y, wa~ evaluated for 30 dimethylamine ~ele~tivity by a procedure ~ubstantially 6imilar ~o ~ha~ de~cribed in Example 1. The condition~ and re6ultfi are ~et f~rth i~ Table I~.

* denotes trade mark ' ,~

12~G61Z
J

COMPARATIVE E~PERIMENT E
In a procedure ~ub6tantially ~imi1ar to that deEcribed in Example 1, methanol and ammonia were ea~sed over a cataly~t consisting of 2 g of ~ilica-alumina (~1~ A12O3, 6.5% SiO2: Har~haw Chemical Co., Al-1602T). The conditions and result~
are di~played in Table IX, below.

Table IX: ~ethylamine Selectivitie6 of E~ionite, 10- and 12-Rin~ ~eolites, and Silica-Alumina Catalvst~
~eOH-Feed ~eOH MA Selectivity Compara~ive T Flow Conv. Conv. (%~
~xPeriment Catalyst (~ ~mL/hr~ L~ MMA DMA TMA
A H-fercie~ite 400 0.5 94 90 13 Z~ 59 B H-erionite ~00 2 98 ~8 1831 51 15 C H-6ilicalite 400 4 97 929 22 69 E Har6haw 400 6 92 80 1114 75 Al 1602 Equilibrium 400 10 22 68 ~0 : 25 ~:
, : 35 ~:

: 36 .~

, ~ ,,

Claims (16)

37What is claimed is:

1. A process for producing dimethylamine comprising reacting methanol and/or dimethylether and ammonia, in amounts sufficient to provide a carbon/nitrogen (C/N) ratio from about 0.2 to about 1.5, at a temperature from about 250°C to about 450°C, in the presence of a catalytic amount of an acidic zeolite rho.

2. A process according to Claim 1, conducted at a pressure from 7 to 7000 kPa and at a reactant feed rate sufficient to provide a methanol/DME space time of 0.01 to 80 hours.

3. A process according to Claim 2, wherein the temperature is from 300°C to 400°C.

4. A process according to Claim 3, wherein the pressure is from 70 to 3000 kPa, and the methanol/DME space time is from 0.10 to 1.5 hours.

5. A process according to Claim 4, wherein the C/N ratio is from about 0.5 to about 1.2.

6. A process according to Claim 1, wherein the zeolite catalyst is zeolite H-rho.

7. A process according to Claim 2, wherein the zeolite catalyst is zeolite H-rho.

8. A process according to Claim 3, wherein the zeolite catalyst is zeolite H-rho.

9. A process according to Claim 4, wherein the zeolite catalyst is zeolite H-rho.

10. A process according to Claim 5, wherein the zeolite catalyst is zeolite H-rho.

11. A process according to Claim 6, wherein the zeolite catalyst is zeolite H-rho prepared by calcination of NH4-rho at a temperature from 400°C to 800°C.

12. A process according to Claim 11, wherein the zeolite catalyst is zeolite H-rho prepared by calcination of NH4-rho under shallow-bed conditions at a temperature from 600°C to 750°C.

13. A process according to Claim 11, wherein the zeolite catalyst is zeolite H-rho prepared by calcination of NH4-rho under deep-bed conditions at a temperature from 500°C to 800°C.

14. A process according to Claim 13, wherein the zeolite catalyst is zeolite H-rho prepared by calcination of NH4-rho under deep-bed conditions at a temperature from 500°C to 650°C.

15. A process according to Claim 10, wherein the zeolite catalyst is zeolite H-rho prepared by treating zeolite H-rho with 0.5 to 5 N NaOH, contacting the resulting product with aqueous NH4+, and calcining at a temperature from 500°C to 650°C.

16. A process according to Claim 5, wherein the zeolite catalyst is zeolite Ca-rho.