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The cataloytic preparation of ether from alcohol by means of aluminum oxide Graham, William Ernest 1925

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THE CATALYTIC PREPARATION OF ETHER FROM ALCOHOL BY MEANS OF ALUMINUM OXIDE by William Ernest Graham 0O0 A Thesis submitted for the Degree of MASTER OF APPLIED SCIENCE in the Department of CHEMISTRY 0O0 THE CATALYTIC PREPARATION OF ETHER FROM ALCOHOL BY MEANS OF ALUMINUM OXIDE by Wi l l i am E r n e s t Graham 0O0 A T h e s i s s u b m i t t e d f o r t h e Degree of MASTER OF APPLIED SCIENCE in t h e Department of CHEMISTRY 0O0 The U n i v e r s i t y of B r i t i s h Columbia APRIL 1 9 3 5 . CUMA^V^XL TABLE OE CONTENTS. INTRODUCTION. APPARATUS AND PROCEEDURE. METHOD OP ANALYSIS. PREPARATION OP CATALYSTS AND REAGENTS. R e a g e n t s . C a t a l y s t s . Note on t h e Washing of Aluminum Hydroxide P r e c i p i t a t e s . CALCULATIONS AND ACCURACY OP RESULTS. RESULTS AND DISCUSSION. D e h y d r a t i o n of A lcoho l t o E t h e r . E f fec t of R e - r u n n i n g t h e P r o d u c t s . E f f ec t of Tempera tu re o n ' t h e R e a c t i o n . E f f ec t of T races of A l k a l i on C a t a l y t i c A o t i v i t y . D u r a t i o n of C a t a l y s t L i f e . Fo rma t ion of Alcohol from E t h e r and Wa te r . Heat of R e a c t i o n and Thermal D a t a . D i s c u s s i o n of Var ious C a t a l y s t s fo r E t h e r P r o d u c t i o n . -SUMMARY. CONCLUSION c»mm«co'"l ftipetti. BIB110 GRAPH Y. THE CATALYTIC PREPARATION OF ETHER PROM ALCOHOL BY MEANS OP ALUMINUM OXIDE. INTRODUCTION. Considerable work has been done on the dehydrat ion of a lcohol in the gaseous phase by means of s o l i d c a t a l y s t s . Jhe c a t a l y s t s which have been used have been of many types* but m e t a l l i c oxides have found the g r e a t e s t f avor , and of t h e s e alumina appears t o be the most e f f i c i e n t and the most widely employed. In the dehydrat ion of e t h y l a loohol alumina beoomes a o t i v e a t tempera tures above 3 0 0 ° c , " g iv ing i n c r e a s i n g amounts of e ther with increase of temperature .At 350° the y i e l d of e the r i s high and r e a d i e s a maximum value*for as t h e temperature i s r a i s e d s t i l l f u r t h e r * i n c r e a s i n g amounts of e thy lene begin t o be formed and t h e y i e l d of e ther i s cut down accordingly .Above 300 the product of dehydrat ion 1,2. i s mainly e t h y l e n e . Pure e t h e r i s»a l so ,dehyd ra t ed r e a d i l y to e thylene a t , a n d above 350.There i s some d i f fe rence of opinion among the d i f f e r e n t workers as to the mechanism of these reao t ions .The dehydrat ion of a lcohol t o e ther and e thy l ene may ooour in two independent s t e p s : 3 C2H;50H—•*• (CsH5)20 + H30,and C.H OH - > C H +- H30 .This , Sender ens cons ide r s t o be the mechanism.The dehydrat ion t o e thylene 1 Senderens,Ann.Chim.Phys. ,(6) 35,505 (1813) . 3 I p a t i e w , B e r . , S 7 , 3886 (1804) . 3 may occur in two success ive s t e p s however t 3 c2H-0H —> (CjgH^sO +• H20,and ( C j O ^ -*> CgH^ +• HgO .Ipat iew concludes t h a t the l a t t e r i s the mechanism. Pease and Yung° consider t h a t i t i s not necessary to p o s t u l a t e e i t h e r of the two mechanisms to the Sxolusion of the o ther .Prom t h i s i n v e s t i -ga t ion repor ted herewith i t would seem qu i t e probable t h a t the r e a c t i o n prooeeds according to both mechanisms simul-t a n e o u s l y . Ipatiew* working a t high tempera tures and pressures* wi th aluminum oxide has dehydrated a loohol to e ther and e t h y l e n e and furthermore has shown the r e a c t i o n to be re_ v e r s i b l e , having ob ta ined an apprec iab le amount of a loohol from equimoleoular q u a n t i t i e s of e ther and water .Sender ens, as r e s u l t of cons iderab le work*has r e p o r t e d a good yieldcff e t h e r from a lcohol by means of aluminum oxide p repared by dehydra t ing t h e hydroxide p r e o i p i t a t e d from s o l u t i o n s of sodium aluminate by means of su lphur io aoid.He cons ide rs t h i s form of alumina b e t t e r than tha t ob ta ined by p r e c i -p i t a t i n g the hydroxide from s o l u t i o n s of aluminum s a l t s by means of ammonia. Mailhe and de Godon were a b i e to get a 71$ y i e l d of e ther a t ISO0 u s ing anhydrous aluminum su lpha te as c a t a l y s t .They showed the inf luenoe of i nc r ea s ing the amount of o a t a l y s t by o b t a i n i n g higher and higher y i e l d s .Pease and Yung repor t a 60$ y i e l d of e ther a t 250° with alumina prepared from aluminum n i t r a t e and ammonia. I t i s gene ra l ly aocepted»in fac t almost e s t ab l i shed , 3 Pease and Yung>J.Am.Chem.Soo.,46,390 (1934) 4 l a i l h e & de Godon,Bull .eoo.chim. ,35,565 (1916) 5 that the r e s u l t s of ca ta lys i s are due to reactions taking place at surfaoe of the catalyst material in the case of heterogeneous systems .Older theory postulated the formation of def ini te intermediate chemical compounds which are un_ s table and break down to give the react ion produots.This, Senderens considers to be the case in t h i s reaction* a oomplex involving one moleoule each of alumina and alcohol being formed which may break down d i r ec t l y to give ethy-lene or which may react with another molecule of alcohol to give ether .The more recent explanation i s that cataly-s i s i s the resu l t of the molecules being brought into pos i -t i o n for reaotion as a resu l t of adsorption on the surface of the catalyst .Moleoular a t t r ac t ion of every degree between t h a t of d is t inot chemical combination and that of loose adhesion i s considered to ex i s t . I n ei ther oase i t i s eas i ly believed that the extent of the surface of the ca ta lys t wi l l p lay a considerable par t in the act ivat ion of the reac t ion . JJpie idea that the spacing of atoms or moleoules would be a fac tor in oa ta ly t io reactions at surfaces was f i r s t spoken 5 of by Langtnuir . Experimental evidence of t h i s has la te r been given by Adkins who has been able to se lec t ive ly ac t iva te alumina for specifio react ions by regula t ing the s ize of the i n t e r s t i c e s in the maleoules, or pores of mole-cular dimensions in the oxide .Senderens considers the alumina prepared from sodium aluminate more aotive than dehydrated col lo idal alumina.This difference may be explain-ed as due to a difference in s t ruc ture ,as the former p r e c i -oLangmuir , Trans .Far,Soo., 17 .617 (1922) through C,A.16,7(193#) 6 Adkins, J.Am. Chem.Soo., 44,265,3175 (1933) ;45, ISO (1934) 4 p i t ate i s def in i te ly c rys ta l l ine and the l a t t e r amorphous. , Prom a consideration of the above i t would seem highly poss ib le to obtain a ca ta lys t more aotive in ether formation than any hi ther to prepared. The purpose of t h i s inve st i gat icn was to determine the catalyst most eff ioient in the production of e ther . Different ca ta lys t s have been prepared in ways which would give p rec ip i t a t e s of differ ing na ture . The investigation i s considered to have been quite success-f u l . I t has been mentioned that work on t h i s problem has been done by Pease and Yung,During the oourse of th i» inves t iga t ion two papers ' on t h i s reaction appeared by them.In the former they reported a maximum yield of 60$ dehydration t o ether at 350°C.In the l a t t e r paper were given data for an equilibrium in the ether-alooho 1-water reaotion showing a maximum possible conversion of alcohol to ether of 62$ at 375°.Calculations from the data given by them show the equilibrium to correspond to a maximum conversion of less than 66$ at 350 .The resu l t s of our work show yields considerably higher than t h i s with several c a t a l y s t s as wil l be ful ly demonstrated la te r : we have obtained yields of over 60$ at 350 .The resu l t s of Senderens work undoubtedly show yields higher than 66 $ but Senderens i s indefini te as regards d e t a i l s . This faot i s indicated by a separation of the product into layers and Pease and Yung s t a t e tha t the products they obtained did not separate into 7 (a) van Br enamel en, Re c . t rav.chim. , 7,75(1668) ; - (b) Martin,Mon.Sci.,(5) 6,335. (1.915) through Ch.Abst ,10,571. 8Pease and Yung, J.Am.Chem.Soo .,46,3397 (1934)/ o layers.These fac ts indicate that the equilibrium in the reaotion cannot be where Pease and Yung have placed i t .That the react ion is»however,reversible i s undoubtedly the oase. It was f i r s t shown by Ipatiew and has also been shown in t h i s inves t iga t ion . As an explanation for the disagreement in equilibrium / values such as i s shown her&ithe idea has been presented that a shif t in equilibrium may be brought about by a sol id c. ca ta lys t .The idea has been mentioned by Bancroft" and Edgar and Sohuyler s ta te that t h i s explanation was offered at the Roohester meeting of the American Chemical Society in April 1931 to account for certain anomalies in e s t e r i f ioation e q u i l i b r i a presented in a paper by Reid and Mulliken.There i s no good evidence for such a viewpointjjiowever. In determining the i r equilibrium data Pease and Yung have made determinations at lSO°Using sulphuric acid as a catalyst and at 375° using alumina.The work of Edgar and Schuyler on e s t e r i f ioation equ i l ib r i a show tha t the equilibrium in the gaseous phase may be higher than in the l iquid phase and they oonolude that the equ i l ib r i a are in general not the same .From t h i s i t i s open to question whether the data of Pease and Yung are oonparable in the two oases. Another point worth notice i s that we have always obtained small amounts of ethylene,and the fact tha t t h i s react ion i s also catalyzed complicate* the oase .Pease and Yung claim that in t h e i r equ i l ib r i a determinations no appre-c iable amounts of ethylene were formed.This would indicate 9 Bancroft,J.Phys.Chem.,31,603,(1917) 10 Edgar and Sohuyler,J.Amer .Chem.Soc, 46,64 (1934), 6 t h a t t he alumina o a t a l y s t used in tha t case was not very a c t i v e , a s at 2?5 t h e e thylene r e a o t i o n i s o r d i n a r i l y c a t a -lyzed s t r o n g l y . They s t a t e t h a t t h i s c a t a l y s t was not as a c t i v e as tha t used in the k i n e t i o measurements of t h e i r f i r s t p a p e r . With the method of a n a l y s i s a v a i l a b l e i t would be r a t h e r u n s a t i s f a c t o r y to attempt t o determine t h e equ i l ib r ium po in t of t h e r e a c t i o n other than approximate ly . APPARATUS AND PROCBEDURE. In ca r ry ing out t h e experiments a flow method has been used th roughou t . The arrangement of t h e appara tus i s shown in P i g . l with the furnace in p o s i t i o n and in F i g . 3 with t h e furnaoe removed. The proceedure cons i s t ed in p a s s i n g a d e f i n i t e volume of l i q u i d a lcohol in to a hot tube f i l l e d with t h e c a t a l y s t . The a lcohol vapor ized on contact with t h e hot surface of t h e t u b e . The vapors then passed on over the o a t a l y s t and out through a condenii* »the l i q u i f ied produot s being d e t a i n e d in a bu lb a t t ached to t h e condenser and the gases p a s s i n g over to an a s p i r a t o r con ta in ing a s a t u r a t e d sodium ch lo r i de s o l u t i o n . Before a run was made fo r a n a l y s i s about 15 oo . of a l coho l were passed over t b e o a t a l y s t to make sure t h e l a t t e r was*in a s teady s t a t e dur ing the r u n . Several methods were t r i e d f o r i n t roduc ing the a l coho l in to t h e r e a o t i o n t u b e . The method used must be such t h a t the a lcohol oan be passed over t h e c a t a l y s t a t a con-t r o l l e d s teady r a t e . Sealed connect ions were used wherever p o s s i b l e and in other oases corks were used i n s t ead of 7 lu l l fUillilllUluil ft FigJ[ - Apparatus with furnaoe in p o s i t i o n . P i g . 3 _ Apparatus with furnace removed,showing connections with oa ta lys t tube* 8 rubber connections on account of the sulphur content of thB l a t t e r . In the f i r s t experiments a heating element was used to pass alcohol vapor into the tube.The f ina l form of t h i s vaporizer consisted of a glass bulb with platinum heat ing coi l with leads sealed through the glass,and de l i_ very and f i l l i n g tubes sealed on.The vaporizer method has the following disadvantages: The apparatus must be discon-nected af ter every run»with possible loss of aloohol vapors; the r a t e of vaporization i s not eas i ly control led c o n s i d e r -able time i s required in heating the aloohol to boi l ing and the vaporizer must be oooled after eaoh run for weighing. I t was decided to t ry a method of introducing the aloohol from a graduated vessel and allowing the vaporiza-t i o n to take plaoe in the hot ca ta lys t tube.Adkine oonsiders t h a t vaporization of the reaotants by dropping on hot sur-faoes unsat isfactory but we have found i t to be quite su i tab le for a vo la t i l e substance l ike e thyl aloohol.The apparatus was arranged as follows: A oapi l la ry tube bent at r igh t angles was sealed on to the top of a b u r e t t e ; a side tube bent upward at r ight angles was sealed into the buret te near the t o p ; a dropping funnel with a oapi l la ry tube stop-cook sealed on at the end of i t s stem was inser ted into the side tube of the buret te through a corkja seoond dropping funnel was sealed into the buret te near the top for r e f i l l i n g with aloohol,The oapi l lary -tube was introduced into the furnace .Mercury was allowed to drop at a control led ra te s from the dropping funnel into the buret te foroing the alcohol into the cata lyst chamber .The length of mercury column was about 45 cm.and the rate of flow was eas i ly cont ro l led by regula t ing the stop_oook .The flow i s easier to control if the edges of the hole in the stopper are scraped back a l i t t l e .The ra te of flow for a short column of mercury was found to be d i f f icu l t to control,The amount of alcohol passed over the cata lyst was read off from the b u r e t t e . This apparatus oould be left connected to the furnace for several runs,fresh alcohol being introduced in to the buret te by drawing off the mercury at the bottom and allowing fresh aloohol t o run in at the top .This method was very eas i ly controlled and quite sa t i s fac to ry . The oata lys t mass was ground up and spread along a pyrex tube about 1.6 cm.in diameter»almost f i l l i n g i t for a length of 120 cm.A small ou t le t tube was sealed on one end.The oatalyst tube was s l i gh t l y longer than the hea t ing furnace and was placed inside the heating element of the l a t t e r . The fumaoe was e l e c t r i c a l l y heated,I t consisted of a 1 1/4" iron pipe insulated with a thin sheet of asbestos and wound with nichrome resis tance wixe.The ear ly experiments were oarried out in a SO" furnace>but l a t e r a 54* furnace was constructed to permit the use of more ca ta lys t .Concentric with the iron pipe was a 5" stove pipe jacket*the two pipes being held in place by means of two asbestos board p l a t e s with convenient grooves turned in 10 them to f i t over the pipes,and a hole in the centre of eaoh to allow the inser t ion of the react ion tube.The temperature was measured by a thermometer placed between the reaction tube and the iron pipe .This was more convenient than one in the oatalyst tube and on t e s t was found to reg is te r sensibly the same temperature»part icularly so when the furnace was in a steady state.With a large furnace such as th is , tem-pera ture regula t ion was quite easy. On aocotint of the v o l a t i l i t y of ether an eff ic ient condenser was a prime requ i s i t e .TEo get the most accurate r e s u l t s in weigh-in® the condensed products, the condenser and rece iv ing vessel were made in one pieoe and as l igh t as possible .A sp i r a l of glass tubing was sealed into a bulbj a s t ra igh t v e r t i c a l tube was sealed on to allow the escape of ethylene to the aspirator and act as a reflux condenser for any entrained ether vapor .The expansion of the gas into the bulb helped to condense the ether and only.negl igible amounts escaped,The condensate was removed through a stop-cook at the bottom .The ethylene was oolleoted over saturated sodium chloride solution which was soon sa tura ted with the gas and served quite well.The pressure was kept almost at atmospheric .The condenser was kept in a ooId bath and only in exceptional case3 when the ethylene y ie ld was high was any appreciable amount of ether carr ied over with the gas. 11 METHOD OP MALY8IS. Considerable d i f f i c u l t y was encountered in g e t t i n g a s u i t a b l e method of ana lys i s .The l i t e r a t u r e on the subject was of l i t t l e a v a i l .Some work was done on a method of d i f f e r e n t i a l ox ida t ion of e ther and a lcohol with u n s a t i s . f a o t o r y r e s u i t a . Pease and Yung in t h e i r pape r s on t h i s r e a o t i o n made use of a s a l t i n g out method of determining e ther in m i x t u r e s of ether , a l coho l and water.They show a ourve for t h e c o r r e c t i o n which i t i s necessa ry to apply to the observed volume of e ther s e p a r a t i n g out from the mixture when t h e l a t t e r i s shaken up with s a t u r a t e d so lu t ion ef sodium ch lo r ide in t h e presence of an exoeas of t h e s o l i d s a l t . I t was found impossible t o get r e s u l t s t o oheok with t h e ha l f of t h e i r curve corresponding to lower pe rcen tages of e the r . I t was found t h a t t he amount of e ther s e p a r a t i n g depended on the r a t i o of e ther to a lcohol and on the r a t i o of volumes of the sample analyzed and t h a t of s a l t so lu t i on . The disagreement with t h e i r curve may have been due to the composit ion of the mix tu res dea l t wi th ,and since Pease and Yung used l a rge r amounts of a lcohol in t h e i r runs than i t was d e s i r e d t o use he re ,o r than were necessa ry for acouracy* i t was found necessa ry to oompile d a t a based on mixtures of t h e same t o t a l volume and con ta in ing e t h e r , a l c o h o l and water in n e a r l y t h e same p r o p o r t i o n s as would be ob ta ined from the c a t a l y s t t ube .Th i s was a l l the more neoessary 13 ainoe with the most aotive ca ta lys t s the products separated into two layers in which case the en t i re product would have to be taken in the analysis .This l a t t e r faot el iminated al together a method of analysis by specific gravi ty determination, A method of analysis based on the above was 11 worked out in t h i s laboratory by Miss A.(J.Winter. The problem was attacked as follows: A ser ies of determinations with mixtures of known composition corresponding to d i f ferent percentages of conversion of an or ig ina l volume of 30 oo .of alcohol was made and a curve p lo t t ed showing t h e correction necessary to be applied to the volume separa t ing when the mixtures were shaken up with 100 oo. of saturated sa l t solution .An excess of sol id sal t was always present as some was always displaced by the alcohol in the mixture. These mixtures were made up by volume at 15°C.and contained ether ,a lcohol and water in the propor, t i o n s in which they would occur in the products from the dehydration of alcohol .Sinoe the volumes of ether ,aloohol and water mixtures are very nearly the same as the volume of the alcohol equivalent as shown by the specif ic gravity 12 t ab le s of Sanfourche and Boutin the method could be d i r ec t l y applied to t h i s work.To allow for a s l ight conver-sion to ethylene a small excess of alcohol was passed over the oatalyst .The resu l t ing product would contain a l i t t l e more water than the equivalent of the ether .Test determina-11 Miss Winter,The s i s submitted for the degree of B.A.,at fhe University of Br i t i sh Columbia, Apr i l 1935. 13 Sanfourche and Bout in»Bull .Soo.Chim.T i). 51,456,(1933) through Pease and Yung»ref . 3 . IS t i ons were therefore made with mixtures containing small amounts of added water but showed no difference in ths amount of ether separat ing. Mixtures in which the volume of ether was kept constant and that of the alcohol varied gave no appreciable r e l a t i v e change in the necessary correction.The method i s acourate to Vjo for mixtures having the composition of those for which the data were compiled. The mixture to be analyzed (30 cc . in volume) was shaken up with a saturated sodium chloride solution in a 100 oo.volumetric flask to which a buret te stem had been sealed close to the bulb,The mixture was kept in a bath at 10° and repeatedly shaken u n t i l the volume separating became constant . A curve i s given (Pig.o) from the data t abu la ted vTable 1) showing the observed volume separating at 10° against the t rue volume at 15° .There was no 103s of e the r when the flask was well corked and kept in the cold bath.The design of1 the condenser enabled t ransfer of the products to the flask to be made with a minimum escape of vapors.The method i s very convenient owing to the short time required for a determination. The method may be used as a rapid approximate method for the de t e rmina t ion ,^ , e the r in mixtures of composition dif fer ing from those for which the data are given .The error i s considered to be within 2$ in the extreme for such cases and for the moat pa r t within 2 fo. The method becomes inexact however»in a l l cases,when the volume of the e the r becomes less than Z>0/o of t h a t of the alcohol . 14 Table 1 . Compos i t ion of m i x t u r e , 1 5 ° Volume C o r r e c t i o n E t h e r A l c c h o l Water s e p a r a t i n g CO . 17 .8 16. 5 U . S 13.6 10.7 8.9 6 . 9 5 . 3 3 . 8 cc . 0.00 3.00 4.00 5.7 fc.o 10.0 13,0 1S.6 15.8 oc. s.t 3 . 8 3 . 5 3 . 3 1.6 1.5 1.35 o.s 0 . 6 cc. 16 .5 15 .05 1 5 . 1 11.7 S.6 7.S 6 .0 4 .5 1.3 PREPARATION OP CATALYSTS AND REAGENTS. ALCOHOL: 95$ a l c c h o l was r e f l u x e d o v e r l ime and d i s t i l l e d and was i n a l l c a s e s p r a c t i c a l l y a b s o l u t e . In some of t h e e a r l i e r work a b s o l u t e a l c o h o l as p u r c h a s e d from Malldinckrodt Chemica l Worlds was u s e d . E t h e r : The e t h e r u s e d was Merck18 a b s o l u t e e t h e r d i s t i l l e d o v e r sodium . The s p e o i f i o g r a v i t i e s of t h e e t h e r and a l c o h o l were d e t e r m i n e d a t 15° and c a l c u l a t i o n s made from t h e s e v a l u e s . S p e c i f i c g r a v i t y of t h e a l c o h o l was .7S5 and of t h e e t h e r ,712 , CATALYSTS: In t h e e a r l y p a r t of t h i s i n v e s t i g a t i o n i t was found q u i t e e a s y t o p r e p a r e a c a t a l y s t a c t i v e in e t h y l e n e f o r m a t i o n but which was no t n e a r l y so a o t i v e i n e t h e r c c . 1.5 1.25 1.3 1.1 1.1 1.0 0 .9 O.S 3 . 1 1 TY) * • * » * * »*. »f <« <a T ^ w Ml >4 X <^  - 1 i i • • • • t .1 j 1 :—[ - - • ~ i ' 1 TT-4-r-•• j " r -L ' _ . -• ' • • " > " • > 1 .-- " — 1 ~ • 1 — — L • -~k ~ t ~ ' ' . ; ' ) • • , j • • i ' \ i • : ' • ' • ! • • . " • • ] -. 1 ... 1 j 1 ••]'•' "-"1 ' : 1 ... j . , . j . — 4 — : 1 ---Irt-rr' i • i ' 1 i l l ; : --j" ' ' L "' : r-i iT • i""' ; ; • : . : ! : - • • — 1 - ~ -. • I > ' I • • ! i • • i • -'• T'"•"• - • 4 , l ! \ • 1 K ; ;! I '. ; TTri;. J ^ u._. . . „ „ l . - r -: • . --1 j : 1 ' !•• i l - ' . ' i !"' r:; j , i :, ; ...... J.... 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'1 ! ) ' • . i 1" • | : j . ; ; i ". i . i i —i |-. i . j . | -I f ""• j 1 • : • 1 j ' i ' i • i i j • ... !. j —^ ^—- *-*r — H— —'rr-r-| i p | 44 s ..'-' ~|: . 1 • 1 - . I • ; ' • ; 4 . 'i .,['.. "I^_ I . i • •; ; :- • • " ; ' j - ' • . ' ! • j , : ' j " i ' i ; ' : ' . • " _„_ L : - 4 - - * -„i,.-. i-4.™„L_-1 > •••; i i > yM '••. I-' ' i •i-l:.--! '":. j 1 : - — H — ^ : • 1 ! ••• j '"• U : LL . i -'",;j • • ! i : 1 iJ_;_; * © : i -"r*h"^ " "'in i- !• 1 i ~ l ! -• , . j . . ... __^ __j "j ' ~Lrr|-•r v , :;l 1 ' ••- i . ' — „ . ^ ~ . - ; -;::l:i:L: 1 i ; K .i. -.-..!. JL-+.-~ \ *-4 rf-• : ; ' • -' , . ! " . : L \ i - " ' ~ * — * • * ~ ~ ! - -^-~~—— — [••'::- ..•• j:..U- - -1 : 1 ' ! • | ; f _ - p -\ J . , . , • ' • : ' . • • ! " • i +_..„,. „..... i . . _L—i 1 — _ _ . '+ lb .Hi:-' ' . ' . - -rLi-. -. „ . —n—, - ' L [ 4 4 . : •  - : j - ' . i • — 1 — • -i j / -J ' -y£+r"~ -J ___j ] , _j :. 1 - - — - • • - ! — — — - " • ! • ' — . 1 __J_ l....;.|... ] T i" !:' 4 • • ' • __ i ' • 1 '. L : 1 1 i . i .. —L t • " " ! ! • True \Zofume in cc.at15 "C ^ ' 9 - 5 . - Correction Chart rer tth er Qetertninotion. 15 format ion .Sinoe the purpose of t h i s work was to determine the best catalyst for e ther , ca ta lys t s which gave large y ie lds of ethylene at r e l a t ive ly low temperatures- as under 260 _ were discarded and few quant i ta t ive measure-ments made with them .Since a l l previous work shows the produots of alcohol decomposition over alumina at t h i s temperature to be almost en t i r e ly ether or ethylene t h i s was considered a ju s t i f i ab l e proceedure and much time was aaved thereby. Of the alumina ca ta lys t s used in alcohol dehydration t h a t prepared by p rec ip i t a t i on from a solution of an aluminum sal t with ammonia seems to have been used most often .Senderens has however, shown tha t alumina prepared from sodium aluminate by p rec ip i t a t ion with sulphurio aoid i s more act ive in ether formation,The p rec ip i t a t e in the former oase i s quite amorphous while tha t in the l a t t e r oase i s considered to be c r y s t a l l i n e . Both are readi ly soluble in acids and alkalies.The hydroxides formed in these p r ec ip i t a t i ons were dehydrated by heating to tempera-t u r e s not over 400°. In t h i s invest igat ion the f i r s t ca ta lys t s made were obtained by following the ra ther indefini te data given by Sendereas as olosely as pos s ib l e . l t wa3 thought that the most active catalyst would be obtained by increasing the surface of the p a r t i c l e s of the p rec ip i t a t e .Accordingly the p r e c i p i t a t i o n was carr ied out in solutions of varying d i l u t i o n .An attempt was made to spread the p rec ip i t a t e out 16", on a support suoh as glass wool from very d i lu te so lu t ions . It was further thought that the use of a very weak acid 3uch as oarbonio aoid would give a muoh finer preo ip i ta te than s u l p h u r i c Some ca ta lys t s were prepared by bubbling C03 through solutions of sodium aluminate. l t i s also known t h a t solutions of sodium aluminate in which the fcatio of AloO^ : Na.0 i s under 1:3 wi l l deoompose slowly on standing, due to hydrolysis , giving a c rys ta l l ine p reo ip i t a te of 15 aluminum hydroxide. Cat i lys ts were prepared in t h i s manner .The p reo ip i t a t e obtained by means of GOg from a 5$, o r s t ronger ,solut ion of sodium aluminate i s also of the same c rys t a l l i ne nature .These p r e c i p i t a t e s were very insoluble in acids and alkalies.The p r e c i p i t a t e s with sulphuric aoid, while they may be c r y s t a l l i n e are evidently of a different s t ruc tu re as they are read i ly soluble in ac ids . The following general information was gained in regard to the preparat ion of the catalysts .The p r ec ip i t a t e s adsorb impuri t ies such as sodium s a l t s very strongly .Washing with hot water helps to remove the impurit ies but the p r e o i p i t a t e must not be boiled as t h i s coagulates the par t iolo s.Washing i s best carr ied out by means of deoantation as f i l t r a t i o n i s apt to contaminate the p rec ip i t a t e with f i l t e r paper . Where f i l t e r i n g i s necessary a layer next to the paper must be scraped off and discarded.Pure water must be used and in t h i s work d i s t i l l e d water was used through-out .Prec ip i ta t ion from concentrated solutions with sulphuric 13(a) Di t te , Compt.Rend., 116,165 (16S5) (b) Russ.:, Zt.Anorg.Chem.41,316 (1SG4) 17 acid gives a lumpy p rec ip i t a t e ,ha rd to wash.It was thought tha t pur i f i ca t ion by means of d ia lys i s might introduce some iarpurity from the membrane though such a method might have hastened washing.The temperature to which the cata lyst i s heated in dehydration has considerable effect :the best r e s u l t s were obtained by heating the p rec ip i t a t e to 400 G. Heating to higher temperatures i s apt to be injurious as i t tends to ointer the oxide .The p r e c i p i t a t e s on glass wool were not very act ive ,poss ibly owing to contamination from the glass wool.These p reo ip i t a t e s were not of the structure found to be the best for the r e a c t i o n . The preparat ion of the best ca ta lys t s i s described in d e t a i l . Two different l o t s of sodium aluminate were used which wi l l be refer red to as I and II,Lot £ ooirtained 10$ moisture and considerable excess a lka l i .Lot I I contained 18$ moisture and l i t t l e excess a l k a l i . Catalyst JL t 800 grams of sodium aluminate I were dissolved in 1© l i t r e s of water .An equivalent amount of sulphuric acid in the same volume was allowed to drop slowly into the a lkal ine solution with constant agitation.The p rec ip i t a t e was washed by decant at ion u n t i l the wash water fa i l ed to give a t e s t for sulphate and then f i l tered.The f i l t e r oake wa3 then s t i r r e d up in nearly boi l ing water,deoanted two or th ree times and f i l t e r e d again.The preo ip i ta te was then dried in an oven at 120° for about 24 hours,ground up and heated in the furnace to about 250°.i t was then considered ready for use . This oatalyst was successfully duplicated. The maximum yield obtained with i t was 74.5$. IS Catalyst B : 1000 grams of aluminate I were dissolved in 18 l i t r e s of water and CO2 bubbled through the solution at a moderate ra te u n t i l a l l the aluminum was preoip i ta ted as hydroxide .This point was determined by f i l t e r i n g a l i t t l e of the suspension and t e s t i n g the f i l t r a t e for aluminum. This p r ec ip i t a t e was oxrystalline and washed r e a d i l y . I t was washed in cold water u n t i l i t f a i l ed to give a t e s t f o r a l k a l i with phenolphthalein and then f i l t e r e d and washed once with hot water .On drying at 120° i t beoame very powdery.The best yield with th is catalyst was 77.5$. One attempt to duplicate t h i s oatalyst gave a p r e c i p i t a t e less o rys ta l l ine and much more soluble in acid . This i s a t t r ibu ted to a difference in the composition of t he sodium aluminate which i s known to vary .The preaipi ta t ion i s governed somewhat by the composition of the aluminate. I t oould not be washed free from a lka l i and was considerably l e s s active .The oatalyst was however duplicated in other a t tempts . Oatalyst 0 : This catalyst was sensibly the same in appearanoe ,properties and ac t iv i ty as oatalyst B. 500 grams of aluminate I were dissolved in 4 l i t r e s of water and p reo ip i t a t ed and otherwise t r ea ted the same as B. The best y ie ld obtained was 7S$. Cat alyst D: This i s not in the same class as the best ca ta lys t s but i s included here as an in te res t ing case . Tests were made with a sample of Merck's aluminum IS hydroxide or p rec ip i t a t ed oxide,whioh was dried for the f i r s t run at 250° and la ter at 400°. No other treatment was given t h i s c a t a l y s t . This cata lys t . contained a small amount of free a l k a l i but gave a fa i r yield of ether .The best yield was 69 %% Catalyst E? 600.grams of aluminate I I were dissolved in 4 l i t r e s of water. The solution began to decompose at onoe p r e o i p i t a t i n g aluminum hydroxide. The pred ip i ta te was washed as before but after drying was found to eon-bain a t race of f ree a l k a l i .The p rec ip i t a t e was therefore dried at o50° and washed several t imes in nearly boi l ing water,by whioh means t he a l k a l i was r ead i ly removed.On drying,a t race of a lka l i was s t i l l present whioh was neutra l ized with d i lu te hydro-chlor ic acid and the alumina washed u n t i l no t e s t for chloride was given in the wash water . In these washings i t was found necessary to f i l t e r as the suspension did not se t t l e ,On drying t h i s time no t e s t for a lka l i was obtained. The best y ie ld with t h i s oata lys t was 81 ?o. Catalyst F : The preparat ion of th i s oatalyst waa similar to that of E, 600 grama of aluminate I I were dissolved in 1.8 l i t r e s of water. The specifio gravity of the solution at 30° was 1.18, very nearly the optimum condition for the spontaneous decomposition of sodium aluminate solutions given by Russ., ' After washing several times the p rec ip i -t a t e was dried at 250° and washed again in hot water . I t was thought possible to displace the adsorbed a lka l i by adding 20 acid.The suspension was made s l i gh t ly aoid and the alumina washed u n t i l the wash water gave no t e s t for chloride .Hot water was used. The p rec ip i t a t e was dried again. The best y ie ld with th i s catalyst was 80,5 /o. Note on the Washing of Aluminum Hydroxide P r e c i p i t a t e s : An in te res t ing point was observed in connection with, the o rys ta l l ine p r e c i p i t a t e s such as oatalyst E and P .This has to do with the adsorption of sodium hydroxide by the p reo ip i t a t e .The p r ec ip i t a t e was washed u n t i l the wash water gave no t e s t for a lka l i with phenfclphthalein and onlX a very faint t e s t was observed in the presence of the p r e c i p i t a t e . On drying and moistening the p rec ip i t a t e a s t rong alkal ine reac t ion waa given with the indicator . Successive washings with hot water now removed the a lka l i qui te rapidly . The alumina appeared to hydrate again to a ce r t a in extent and f ina l ly »as before»no t e s t was given for a l k a l i in the wash water. On drying again more a lka l i could be removed and t h i s time the removal was so complete that no further t e s t was given with the ind ica tor . With another sample»before drying*an attempt was made to displace the a lka l i by adding hydrochloric acid. The suspension was made s l i g h t l y acid and the p rec ip i t a t e f i l t e r e d out and dr ied . On drying a t e s t for a lka l i was s t i l l given .This p reo ip i t a t e was washed as above.It was found possible however jto completely remove the free a l k a l i from a dried p r e o i p i t a t e . The p rec ip i t a t e was washed u n t i l the water gave no t e s t for a lka l i »and flame 31 t e s t s showed only a t r a c e of sodium in t h e p r e c i p i t a t e . On seve ra l oooasions o ther p r e o i p i t a t e s , w h i o h a f t e r l ong washing » t i l l s e t t l e d rap id ly , sudden ly on one change of water f a i l e d t o s e t t l e * i n d i c a t i n g t h e acqu i r ing of a charge .This might be expla ined on t h e b a s i s of t h e more complete removal of one of two adsorbed ions than of t h e o t h e r .These phenomena would seem to offer an i n t e r e s t i n g f i e l d for i n v e s t i g a t i o n of ion adsorp t ion both by the hydroxide and the anhydrous oxide .As t h i s was a s ide l i n e of t h i s r e sea roh p r e s s u r e of t ime made i n v e s t i g a t i o n i m p o s s i b l e . CALCULATION AND ACCURACr.OF RESULTS. The r e s u l t s of t h e experiments repor ted in t h i s p a p e r a re c a l c u l a t e d on t h e b a s i s of t h e percentage con-v e r s i o n of the a lcoho l in t roduced in to t h e r e a c t i o n tube i n t o t h e produdta co l l ec t ed .The d a t a given here are a l l f o r oases where t h e dropping method of a lcohol feed WRB u s e d . In t h e s tandard runs by t h i s method about 21 o c . of a l c o h o l were passed in to the t u b e . This was convenient and • u f f i c i e n t to permit accura te measurements as mentioned in connec t ion with the method of a n a l y s i s .After a l lowing f o r a s l i g h t conversion t o e thylene of not over 5 h t h e unconver ted a l coho l»e the r and i t s water equivalent were p r e s e n t in a t o t a l volume of about 30 oc.The method of a n a l y s i s dould be app l i ed d i r e c t l y .The e thylene was 33 measured at room temperature and atmospheric pressure in a carefu l ly graduated aspirator .Corrections were not made to standard conditions as these were deemed neg l ig ib le . A check was made on a l l possible loss of alcohol or products by weighing the condenser and contents and calcula-t i n g the weight of ethylene.The sum of these weights checked with the weight of the aloohol used in a l l cases.Only when the ethylene yield was high was any appreciable quantity of ether carr ied into the gas receiver and t h i s did not occur in the runs here repor ted . As a check on the conversions determined! mixtures containing e ther ,a lcohol and water in the amounts caloulated for a standard ru$ were made up. The amount of ether separa t ing out on analysis from these mixtures was the same as tha t separating for the products of the runs .The ca l -cu la t ions are considered accurate to 1 j». A further indication of high yie lds of ether was best afforded by the fact that for t he / ca t a ly s t s here mentioned the l iqu id products separated out into two layers in the receiving vessel.A separation in such mixtures only occurs when the components are present in proportions co rrespondiag t o approximately BO $ conversion. Exoess water such as would correspond to ethylene formation causes a separation at s l i g h t l y lower conversions to ether .In t h i s wor.li the ethylene formed,and*consequently*the exoess water were very l i t t l e . 35 RESULTS AND DISCUSSION. DEHYDRATION OF ALCOHOL TO ETHER: These experiments have o shown t h a t 3o0 i s the best temperature for e ther format ion . The r e s u l t s show t h a t t h e t o t a l a lcohol dehydrated approaches a maximum value as t h e l eng th of time of t h e c r u n i s i n c r e a s e d . The best r a t e of flow va r i ed with the d i f f e r e n t c a t a l y s t s s l i gh t ly>r$ng ing from 15 to 30 oo.per hour .At r a p i d t a t e s of flow t h e t o t a l dehydrat ion f a l l s off and at slower r a t e s t h e r e l a t i v e amounts of e thylene formed inc rease at the expense of the e ther .This has also been shown by Pease and Yung. R e s u l t s wi th the d i f f e r en t o a t a l y s t s are shown in t a b u l a r fom.The oolumn headed drying temperature r e f e r s t o t h e tempera ture to which t h e c a t a l y s t was heated in d r y i n g . I n some oases a c a t a l y s t was used a f t e r hea t i ng to one tempera ture and then hea ted t o a higher temperature and f u r t h e r t e s t s made. Heating up t o 400 inc reased t h e a c t i v i t y . The react a n t s and p roduc t s were measured by volume throughout and t h e i r weights c a l c u l a t e d . CATALYST A: Table 3 . Time of Drying Temp Weight of Vol . $ conversion . r u n * inrtimins. 66 135 85 65 57 4,9 Temp . 500° rl 400 of r u n . 350±3, A l o . "Ether u s e d . c o l l . 1 6 . 7 0 8 . 3 16, ,55 16 AC 17, 16 . 16 , ,15 .65 ,40 9 . 5 5 9 . 5 0 9.8C 9<.8-5 else of C3H4 210cc 330 750 590 480 530 t o Ether 6 1 . 5 70 70, 71 , 74, 70, .3 .5 .0 .8 .0 to C3H4 3 . 6 3 .7 9*3 7 . 1 5 .9 8.9 34 CATALYST Time r u n : mint 560 65 150 70 75 of Ln 3 . CATALYST Time of r u n i n m i n s . 95 110 305 95 64 71 B: Dry ing Tergp . 500 400 C : Dry ing Temp . Deg .C. 550 400 Tab le 5 . Temp . of r un Deg.C 350*3 « n « H Table 4 Texrp. of r u n Deg .C . 35013 K II N i n n Weight of A l o . E t h e r u s e d o o l l . grams 3 5 . 7 5 14 ,6 14 .40 1 6 . 5 4 1 6 . 5 4 16 .60 • Weight A l o . u s e d gr 1 6 . 6 4 1 6 , 6 3 1 6 . 4 ° 16 .50 16.50 16.50 7 .9 1 0 . 3 1 0 , 3 1 0 , 5 of E t h e r d o l l . ams 10 ,55 10 .65 10 .50 10 .30 10 ,55 10 .55 Vo l .o f C3H4 0 0 . SOO soo 450 340 340 V o l . o f 300 310 540 560 3 40 360 i» c o n v e r s i o n t o t o Ether °Z^i 7 3 . 3 7 . 1 69 .0 lfc .5 7 7 . 5 77 .5 4 .3 6 . 3 5 , 0 3 .9 •f> c o n v e r s i o n t o t o E t h e r CgH^ 7 7 . 3 3 . 5 79 76 76 76 76 .4 .0 .0 ,0 .0 3 . 6 4 .3 4 .7 3 .9 5 .3 CATALYST D: "Time of Drying Temp. run in Temp. of run Mins . Deg.C. Deg.C. 75 108 550 400 Tabled Weight of Vol.of # conversion Alo. Ether CgH^ t o to used c o l l . o c . Ether 03%. in grains. - ^ „ 350*3 16.65 6.4 60 47.7 0.6 16.65 9 .5 110 69.0 1.4 35 CATALYST E: Table 6 . Time of Drying Temp. Weight of Vol. % conversion run in Temp, of run Alo. Ether O3H, to mine . Deg.C, Deg.C. used o o l l . 00 Ether C2H,. in granss So 400 35012 16.5 C 10.73 &?0 60.6 4.5 65 " 16.6C 10.60 160 60.6 3.3 107 " 16.60 10,60 330 60.6. 3.7 o CATALYST F r This c a t a l y s t was .heated a l i t t l e above 400 whioh appears t o have decreased i t s a c t i v i t y a l i t t l e * a s i t was p r epa red t h e same as c a t a l y s t E. The a c t i v i t y appea r s t o have been reoovered with use a s i s shown in f a b l e 7 . I n d i c a t i o n s were given in t h e case of o t h e r c a t a -l y s t s t h a t the a c t i v i t y inc reased with use t o a c e r t a i n p o i n t . The e thy lene 1 B higher with t h i s oa t a lye t than with Table 7 , Time of Drying Temp Weight of Vol % conversion r u n in Temp. of run Alo Ether C3H4 to mine . Deg.C. Deg.C. used o o l l . 00 Ether C^H^ in grams 66 430 35013 16.55 10. S5 iOO 76.0 5.0 67 " 16.55 10.4£ £00 76.5 £.7 65 " 16.50 10.7S £40 60 .5 i . 3 o a t a l y s t E whioh i s a t t r i b u t e d t o the dry ing temperature be ing too h i g h . EFFECI OF WE-RUNIUHG THE PRODUCTS : An attempt was made t o f i n d t h e e f f eo t of use of more o a t a l y e t but owing t o i n a b i l i t y t o c o n t r o l t h e tempera ture in t h e long furnace which had t o be used the idea was abandonned.As an a l ternat ive t h e e f f eo t of r e j r u n n i n g the p roduc t s was de te r mined. About 36 100 oo . of a loohol were passed over t h e oa t a lys t and p r o p o r t i o n a t e amounts of t h e two l a y e r s giving a t o t a l volume of 20 oo .were analyzed.The amount of e ther in the whole produc t and in t h e balance was ca lcu la ted .The remaining product was then pas sed over t h e o a t a l y s t again .The two l a y e r s ware in t roduced in r a t e s p r o p o r t i o n a t e t o t h e i r amounts by means of two droppers u n i t e d in to a oommon d e l i v e r y t u b e . Again a sample con ta in ing the two l a y e r s in p ropo r t i ona t e amounts and having a t o t a l volume of 30 oc .was analyzed.The amount of e ther in t h e whole product was c a l c u l a t e d and was found t o be s l i g h t l y lower than be fo re .Th i s decrease was due t o t h e formation of a l i t t l e e thylene and corresponded t o t h e equivalent of the e thylene olosely .The produots were etentained in two bure t t e s>gradua ted from t h e bottom up, between t h e runs .This enabled equiva len t amounts t o be taken out when d e s i r e d . EFFECT OF TEMPERATURE ON THE REACTION: The temperature effect i s shown by Table & .The runs were made with c a t a l y s t C. Table 6 . Temp. of run Deg .C. 33513 3 4 0 t 3 35013 365*3 Time of r u n i n m i n i . 148 9 3 64 66 Weight A l o . u s e d i n gr 16.5C 1 6 . 5 5 16 .50 17 .OC of V o l . E t h e r CgH^ c o l l e c t e d cc am s 9 . 1 3 1 0 . 0 0 1 0 . 5 5 Q.8% 50 130 340 600 ft c o n v e r s i o n t o E ther C3H 6 9 . 0 7 5 . 0 7 6 . 0 7 5 . 0 0 . 6 1.5 3 . 9 7 . 5 37 EFFECT OF TRACES OF ALKALI ON THE CATALYTIC ACTIVITY: The effeot of t r a c e s of i m p u r i t i e s such aa 30dium hydroxide*and no doubt t h a t of s a l t s ae we l l * i s shown by t h e d a t a in Table 8 . A o a t a l y s t was p repared by t h e spontaneous decomposi t ion of sodium aluminate and should have been in a l l r e s p e c t s t h e same as c a t a l y s t E. On dry ing i t was founA t h a t t r a o e s of f r ee a l k a l i s t i l l remained in t h e p r e c i p i t a t e . The o a t a l y s t was t r i e d out in the fumaoe and a very poor y i e l d r e s u l t e d . The o a t a l y s t was then fu r the r washad and a muoh grea te r a c t i v i t y r e s u l t e d . While the a c t i v i t y was not as great as for t h e best o a t a l y s t i t i e qu i t e probable t h a t s i n c e the o a t a l y s t was used before rewashing the i i p u r i t i e s were not l a t e r a l l removed.The ef feo t of b e t t e r washing is> however, shown in no unmistakable manner. Table 8 . Time of Drying Temp. Weight of Vol . # conversion run in Temp, of run . Alo. Ether C-H. t o mine Peg.C. Deg.C. used c o l l . 3otf Ether C2H4 Before rewash ing : 75 400 330i2 16,60 5.83 60 U>.0 O.fc Af ter rewashing: 6£ " * 17.10 S.fcO 1r30 71.0 5.0 DURATION OF CATALYST LIFE: That the o a t a l y a t s w i l l remain a c t i v e for a cons iderab le l eng th of t ime i s shown by Table 10 f o r a run with o a t a l y s t C a f t e r more than 1000 00 . of a l c o h d had been passed over i t . The a c t i v i t y shows no sign of impairment. 28 Table 10 Temp. Time Weight of Vol of jar convexsion t© of run o f i run Ale Ether C9H. Ether fcCalU 7 it. e. . 250^2 $& 16.55 10,56 500 78.4 5.7 In some oases t h e a lcohol tended to deposi t car_ bonaoeous m a t t e r on the c a t a l y s t which was evidenced by a b l a c k e n i n g of t h e l a t t e r but in t h e case of the bes t c a t a l y s t s t h i s d id not appear t o happen .While t h i s may be due to i m p u r i t i e s in t h e a loohol in some of the oases>for t h e nicest p a r t i t i s considered t o have been due t o the n a t u r e of t h e s ide r e a c t i o n s t a k i n g p laoe with t h e c a t a l y s t i n quest ion .When carbon was depos i t ed on a c a t a l y s t the n a t u r e of t h e r e a c t i o n appeared t o be modified somewhat as more e thy lene was o b t a i n e d , FORMATION OP ALCOHOL PROM ETHER AND WATER: N The r e v e r s i b i l i t y of t h e r e a c t i o n was p rev ious ly ? 5 ti' shown by Ipat iew and l a t e r by Pease and Yung . Some runs were made in which e ther and water in equal molecular amounts were passed over c a t a l y s t C.The amount of e ther and water used in t h e runs were equivalent to a l i t t l e over 2$ oc.of alcohol*. The p r o d u c t s were analyzed and t h e amount of e the r was found t o have been deoreased by an amount cons iderab ly grea ter than t h e equ iva len t of the e t h y l e n e formed .The l a t t e r was t h e same as would have been formed if a s tandard run with a lcohol had been made. The dec r ea se in t h e amount of e ther was undoubtedly due t o / t h e formation of a lcohol according t h e equat ion 29 C3H5OC3H5 •+ H20 —> 2 CaH50H.The r e s u l t s of t hese expe r i -ments are shown in Table 1 1 . The column headed percent Table 1 1 . Temp. Time Weights used Alcohol Weight Vol. Alcohol of run .of run Ether Water Equivalent Ether- C3H4 formed *• Deg.C, mins . grains grams Beco^pred co gms fo c~tJ/f 350t2 63 1£.$C 3.50 16.65 1 1 . Vi 300 3.05 13.3 ff-f • 56 lb .60 S.40 16.90 11.95 150 1.64, 11.0 hi a l c o h o l formed i s based on t h e t o t a l a lcohol equivalent of t h e mix tures passed over t h e furnace .'•The iodoform t e s t was made t o determine t h e presence of a lcohol in t h e p r o d u c t s and a decided r e a c t i o n was g iven . I t i s seen t h a t approaohing from t h e e ther s ide about 12 ft of t h e a lcohol equ iva len t of/xhe mixture i s ob ta ined as a lcohol* t h e time of the run being about t h a t of a s tandard run with a l c o h o l . The appara tus used t o in t roduce e t h e r tod water i n t o the c a t a l y s t tube &t r a t e s of flow p r o p o r t i o n a l to t h e i r e q u i v a l e n t s was t h e double dropper mentioned in connec t ion with r e - runn ing the p rdduo ts (page 25) .The two were jo ined with a common d e l i v e r y tube and meroury dropped i n t o each independent ly . From t h e above i t i s seen tha t fafom t h e e ther s i de j t h e e the r recovered i s equiva len t t o n e a r l y an &&$ conversion t o e the r .From t h e a loohol s ide y i e l d s of abtiut 81 $ have been obta ined.The formation of e thylene complicates t h e c a s e somewhat but fo r t h e purpose of an approximate c a l c u l a -t i o n may be neglec ted .Thus from t h e s e va lues t h e y i e l d cor responding t o t h e equi l ib r ium may be es t imated t o bf 8 5 $ . Thia would mean a mixture con ta in ing 13 .5 mol percent of each e t h e r and water and 15 mol pe rcen t of aloohol.The equi l ibr ium 425 y 425 cona tan t oa lou la t ed from t h e s e va lues i s given by K'l *a . < « ( . 1 5 ) 3 - 6 . 0 . HEAT OP REACTION AKD THERMAL DATA: The thermal da ta given are most 14 t h e / r e l i a b l e v a l u e s ob t a inab l e and are as quoted by Pease and Yung .The h e a t s of vapo r i za t i on are for 30°c and have been o b t a i n e d by Pease and Yung by p l o t t i n g va lues for d i f f e r en t t e m p e r a t u r e s and i n t e r p o l a t i n g for 30 . 4 00 3 * 6 H3fy—* 3 C2H50Ha)> 6O3 -655600 OStlvRi .Em .Ben .) 3 ° 3 H 5 0 % ^ 3 °3 H 5 0 f W - 3 0 6 0 ° ('V"? 3 .C3H50H^ - * (C2H5) a 0 ^ + H30<v) +Q **%,)-*%% - 1 0 4 5 0 / — ' (C2H{.)3O#>-*(O3H5)3O0) -6500 (**.) 6 0 3 + CQaR5)2C|y—>4 003*-5 HgOjj +653,500 fs**»—^> Hence Q * 655800 -f 3 0 6 0 0 - 10450 - 6500 -653500 « 7100 S a l , Adopting L*wis' n o t a t i o n AH *-Qp* -7100 C a l . Prom t h e heat of t h e r e a c t i o n and the above value of t h e equ i l ib r ium constant the s tandard f ree energy of the r e a c t i o n may be c a l c u l a t e d . AP» -RT In K where In s tands fo r t h e logar i thm t o the base e»or A P * -2.505 RT log^cK. AP cornea out t o be - 1560.The s tandard f ree energy change v a r i e s with t h e tempera ture aooording t o the equat ion AP - AH -r IT . Prom t h i s t h e i n t e g r a t i o n cons tan t I may be c a l c u l a t e d and comes out to be 4 .66 .Cons ider ing AH to be constant over t h i s t empera ture range the equ i l ib r ium constant at 375° may be c a l c u l a t e d , AP- . -=-7100 +• 5 4 6 " 4.66 s -4440 .Prom t h i s 946 14 LandoI t -Borns te in , "Tabe l ien" , J .Springer ,Ber l in 1^35 51 log K = .1 ,whence K-.? 5 .68 .This corresponds 1.966 x 548 K3.SOS _o *' t o a maximum.possible conversion at 37 o of 82.8$ which i s much h ighe r t h a n the value given by Pease and Yung. I t i s c e r t a i n t h a t t h e equ i l ib r ium at 375 i s not where Pease and Yung have p l aced i t , Ca lcu la t ions of t h e s tandard f ree energy of e the r a r e s c a r c e l y j u s t i f i e d on the da ta a v a i l a b l e . In add i t i on to t h e p o s s i b l e r e a c t i o n s a l ready mentioned* another r e a c t i o n (C2H_)3 0—"G^ H. -t C3H5OH i s a lso p o s s i b l e . Since the method of a n a l y s i s determines one product only and t h e o t h e r s may vary i n s e v e r a l ways,a de te rmina t ion of t h e exact equi l ib r ium p o i n t i s ha rd ly p o s s i b l e . DISCUSSION OF THE VARIOUS CATALYSTS FOR ETHER FORMATION. With alumina p r e p a r e d by dehydrat ion of t h e p r e c i p i -t a t e from aluminum s a l t s with ammonia only low y i e l d s have been r e p o r t e d by ' t hose who ha^e used t h i s c a t a l y s t * This p r e c i p i t a t e i s very so lub le in ac ids and a l k a l i e s . With the hydroxide p repa red from s o l u t i o n s of sodium aluminate with s u l p h u r i c ac id a y i e l d of 7 4 fa has been obta ined in t h i s i n v e s t i g a t i o n . This p r e o i p i t a t e i s considered to b e ' c r y s t a l l i n e but i t i s r e a d i l y so luble in a c i d s . The p r e o i p i t a t e produced by COg from a ofo o r s t ronger so lu t i on of sodium aluminate i s decidedly c r y s t a l l i n e and very i n s o l u b l e in ac ids and a l k a l i e s . T h i s p r e c i p i t a t e gave a c a t a l y s t y i e l d i n g 76 -79$ e ther .The p r e c i p i t a t e ob ta ined by . 52 the spontaneous decomposition of sodium aluminate gave the most d i f f i c u l t l y soluble p rec ip i t a t e of a l l and was the best catalyst giving a yie ld of 80-81$ e the r . The d i s t inc t ion between col lo idal aluminum hydroxide and the t rue c rys ta l l ine aluminum hydroxide obtained by p r e c i p i t a t i o n from solutions of sodium aluminate was made 7 15 by van Bremmelen and substant iated by Martin.MiHigan Tias shown that the compound Al(OH) -C loses most of i t s water on heat ing to 300 c and af ter being heated above 275° and then allowed to rehydrate, the water i s adsorbed and not ohemioally oombined in the t rue sense .The hydroxide i t s e l f furnishes a d i s t i nc t c rys ta l l ine X-ray pa t t e rn but on heating above S25° gives another pa t t e rn which i s that of a c rys ta l l ine s t a t e according to Mead as quoted by Milligan^but different from the f i r s t , I t would be in te res t ing to observe whether the different p r e c i p i t a t e s from solutions of sodium aluminate whjboh have been used as ca ta lys t s in t h i s work have different p a t t e r n s . The marked difference in the i r so lub i l i ty in aoids indicates a difference in their s t ructure .Until the exact nature of each p r e c i p i t a t e i s determined i t i s not possible to develope a def ini te theory of the mechanism of the react inn . SUMMARY. 1. A study of the ca ta ly t i c dehydration of ethyl alcohol t o ether has been made in the gaseous phase in the presence of alumina at 350 . 3 . The maximum amount of ether was obtained with the 15 Milligan, J.PhyB.Chem,,36,3« (1933) product obtained by dehydration of the orys ta l l ine aluminum hydroxide resu l t ing from the spontaneous decomposition of so lu t ions of sodium aluminate .The highest yields were ototained at 350 and amonnted to QOJ>ii j> of the theore t ica l conversion to e the r . S. Aloohol was obtained from equimoleoular quant i t ies of e the r and water»showing the reaction to be reversible .The pos i t i on of equilibrium has been determined at 350 to correspond to a maximum possible conversion to ether of about &5 ^.The corresponding equilibrium constant i s 8.0 . i . I t has been shown that absolute pur i ty of the catalyst i s e s s e n t i a l . Impurities may be more quiokly tnd completely removed by drying the p rec ip i t a t e and washing again.-5 . Heating the cata lyst to about 400° lout not higherjin drying»gives the most active product . 6 . The c a t a l y s t s p repared as desor ibed r e t a i n t h e i r a c t i v i t y , u n i m p a i r e d , a f t e r long u s e . CONCLUSION . The c a t a l y t i c p r e p a r a t i o n of e t h e r by means of aluminum oxide by the method developed in t h i s i n v e s t i g a t i o n has excep t iona l commercial advantages .The p o s s i b l e uses for e t h e r a^e i n c r e a s i n g rap i d l y , n o t only as a solvent but a l so i n mixtures as a motot f u e l » p a r t i c u l a r l y in oold r e g i o n s . A very va luable a p p l i c a t i o n of t h i s use of e t h e r w i l l be to make p o s s i b l e the use of a loohol as a f u e l . The p re sen t method of manufacture,by dehydra t ing a loohol with su lphur ic aoid i s not only c o s t l y but troublesome. £4 The loss of alcohol i s considerable,usually about SO/o and the ac t i v i t y of the sulphuric acid quickly diminishes. In the method above described the cata lyst i s eas i ly prepared and can be exactly duplicated and gives yields higher than are commercially feas ible by the sulphuric aoid method. In view of the large soale upon which t h i s invest igat ion was ca r r i ed out,approaching semi-commercial s i z e , i t i s aafe to consider the high yields obtained can be duplicated commer-c i a l l y .The ca ta lys t s have been shown to re ta in the i r high a c t i v i t y with long use . The mechanical side of the operation i s extremely simple and could be carr ied out with l i t t l e c o s t . 0O0 I wish to take t h i s opportunity of expressing my hea r t i e s t appreciation to Dr.R.H.Clark,Professor of Organic Chemistry>for h i s kind advice and assistance in connection with the work. 0O0 . S£ BIBLIOGRAPHY. Homer Adk ins j Ac t ion of Alumina, T i t a n i a and T h o r i a on E t h y l and I s o p r o p y l A c e t a t e s * J o u r n a l Amer .Chem.Soo . , 44 ,565^1932) The S e l e c t i v e A c t i v a t i o n of Alumina fo r D e c a r b o x y l a t i o n and f o r D e h y d r a t i o n , J.Amer .Chem .Soc . * 44 ,2175 (1932) R e a c t i o n s of Formic Acid a t t h e S u r f a c e of Alumina S e l e c t i v e A c t i v a t i o n of A lumina , J .Amer .Chem.Soo . , 45.S09 (1925) . The C a u s a t i o n of O r g a n i c R e a c t i o n s by Alumina and T h e o r i e s of C a t a l y s i s , J.Amer . C h e m . S o c , 46,150 ( 1 9 3 4 ) . W.D.Bancroft ;Contract C a t a l y s i s I , J o u r n a l of P h y s i c a l Chemis t ry 2 1 , 5 7 5 ( 1 9 1 7 ) » I t h a c a , N . Y . J .-van Bremmelen, ( On C o l l o i d a l and C r y s t a l l i n e Aluminum Hydrox ides ) R e o e u i l dea Travaux Chimiques des Pays-Bas» 7 , 7 5 (1666) L e i d e n , H o l l a n d ( t h r o u g h M i l l i g a n , s e e b e l o w l . A . D i t t e t Decompos i t ion d e s A lumina t e s A l k a l i n s en P r e s e n c e de 1* Alumine»Comptes Rendus hebdomadair-es d e s S^eances de UAcademie S c i e n c e s , 116 ,185 (1S&5) P a r i s . Graham Edgar and W.H.Schuyler j E s t e d r i f i c a t ion E q u i l i b r i a , ±n t h e fijaseous P h a s e , J o u r , Amer .Chem.Soo. , 16 ,64 ( 1 9 2 4 ) . " J . E n g e l d e r : S t u d i e s i n Contac t C a t a l y s i s , J o u r . P h y s i c a l Chem. ,21 ,676 (1917) W l . l p a t i e w K a t a l y t t i s c h e Reac t i c n e n b e i hohen Temper a t u r e n und D r u c k e n , B e r i o t e d e r d e u t s c h e n chemischen G e s s e l l s o h a f t , 5 7 , 3 9 6 6 ( 1 9 0 4 ) , L e i p z i g . S6 . I .Langmuir{Chemical React ions on Surfaoes»Transact ions of t h e Faraday Society,17,617(1922) through Chem.Abstracts (Aii:er.Chem.Soc) 16,7 (1923) E.Martin {Alumina and Aluminates,Moniteur Soient i f ioj ie,(5) 5 ,235(1915)Par i s , th rough Chem.Abst,(ACS> 10,571 (1916) L.Mil l igantThe Mechanism of Dehydration of C r y s t a l l i n e Aluminum Hydrate,and of the Adsorption of Water by the R e s u l t i n g Alumina,Jour.Phys.Chem.,26,21:7 (1923) Ithaca>NY R .N .Pease and Chi Chao Yung: The C a t a l y t i c Dehydration of Ethyl Alcohol and Ether by Almmina, J .Amer .Chen; Soc . , 46,590 (192 4 ) . The P o s i t i o n of Equil ibrium in the Alcohol-Ether React ion a t I'oCP and a t 275^ J .Amer. Chem. Soc . , 16,3597(1934) F .Russ: Uber Tonerdehydrat , Z e i t s o h r i f t fur anorganisohe und al lgemeine Chemie* 41,216 (19C4) , L e i p z i g . A.Sanfourohe and A.M .Boutin :Dens i t i e s and Ref rac t ive Ind ices of Mixtures of Water Alcohol and Ether , Bul le t in de l a Societe* Chiiuique de Pranoe(4)-51,456(1923iParis , through Amer.Chem.Soc .Abst r.»17»65b(1935) and Pease and Yung above J .B.SenderenstDe'shydratat ion Ca ta ly t iques des Aloools p a r Voie Seche»Annales de Chimie et de Physique , (b) 35.505 (1913) , P a r i s . Miss A.G-.Winter: A Qualitative Determination of Ether in Mixtures of E ther , Alcohol and Water .Thesis submit ted for Bachelors DegresUniversi ty ©f B r i t i s h Columbia Apr i l 1935. A.Mailhe and F .de Godon: P r e p a r a t i o n Cata ly t ique pa r ¥oie Seche de 1 'Ether O r d i n a i r e , B u l l e t i n de l a Socie te ' Chimique de France , .35, (1916) 5 6 5 , P a r i s . 

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