TH E INSTITUTE OF PETROLEUM.
A m e e t i n g of th e In s titu te of Petroleum was held a t Manson House, P o rtla n d Place, London, W .l, on W ednesday, May 7, 1947, th e Chair being ta k e n by Mr H . C. T e tt (Vice-President an d Chairm an of Council).
A fter th e G eneral Secretary (Mr F . H. Co e) had read th e nam es of newly elected members, th e Chairm an said : I t is now m y pleasure to h an d th e m eeting over to th e Chairm anship of D r A. P arker, C.B.E., th e D irector of th e Fuel R esearch S tation of th e D ep artm en t of Scientific and In d u stria l Research. D r P ark er is well known to us all, an d we are very fo rtu n ate th a t he has agreed to occupy th e Chair th is evening. H e was closely associated w ith M ajor Gordon in th e work which resulted in th is paper, and I am sure we could n o t wish for a b etter Chairman.
Dr A. Pa r k e r, having form ally occupied th e Chair, said : F irst I will strik e a personal no te and say how much I appreciate th e in vitation to occupy th e Chair, as an outside Chairman, for th e presentation by my old friend M ajor Gordon of his paper on th e developm ent of hydrogenation and Fischer-T ropsch processes in Germany.
I t is m y ta sk to introduce M ajor Gordon, b u t I am certain he is so well know n to everybody here th a t he really needs no introduction. You all know of his outstanding work, particularly a t Billingham, in relation to coal hydrogenation, th e hydrogenation of creosote, tars, and so on, a n d also his work in relation to th e hydrogenation of certain petroleum fractions for th e production of high-octane aviation spirit, which in large m easure helped us to win th e war. W ithout a spirit of th a t kind we certainly should n o t have won th e B attle o f B ritain or have been able to proceed further.
I am n o t sure, however, th a t you know of M ajor Gordon’s activities in relatio n to th e investigation of th e processes in Germany. Some will know ; your Vice-President, Mr T e tt, was one of th e team , and there are others in th e audience who took p a rt in th e investigations in Germany, which began in M arch or early April 1945 before th e w ar was over.
I n th e paper M ajor Gordon has n o t sta te d how this was set up, because th e paper deals w ith technical m atters. B u t I would like to say th a t, a t th e instigation or suggestion of Sir H arold H artley, in th e au tu m n of 1944 th e M inistry of Fuel and Power began to prepare for th e tim e when we could go into G erm any, w ithin a few horns of works and plants being captured, in order to collect inform ation with regard to th e activities there, w ith th e object of assisting to win th e war. The M inistry decided to set up a body—I forget w hether it was called a W orking P a rty or a Group—which came to be know n later as th e Oil Mission, M ajor Gordon being Chairm an. T h a t Oil Mission included specialists in hydrogenation, th e Fischer-T ropsch process, coal carbonization, gasification, petroleum refining, lubricating oil, an d so o n ; and it was divided into a num ber of team s, w ith a leader responsible for each. M ajor Gordon and his colleagues a t Billingham took full responsibility for collecting all the
inform ation on hydrogenation, an d th e F uel R esearch S ta tio n accepted responsibility for th e F ischer-T ropsch process, w hilst others to o k respon
sibility in connexion w ith refining, • lubricating oil, an d so on. An enorm ous am o u n t of w ork was carried out. T he various rep o rts were w ritte n an d m any have been issued by H.M. S tatio n ery Office as B .I.O .S.
reports.
The n e x t stage was to m ake an overall rep o rt dealing w ith processes as a whole—hydrogenation, F ischer-T ropsch, oil refining, ta r refining, ahd so on. The various sections were w ritte n by individuals, an d M ajor G ordon p u t in an enorm ous am o u n t of work w riting a sum m ary of th e whole lot. I am sorry t h a t th e p rin tin g has been so slow th a t it is n o t published y e t; th e w ork has got beyond th e p roof stage, b u t owing to th e fuel crisis th e p rin tin g has been delayed. W hen you see it I am confident you will agree th a t M ajor G ordon, as C hairm an of th e Oil Mission, leader o f one o f th e team s a n d co-ordinator of th e rep o rts, has p u t in a trem endous am o u n t of work.
T h a t is a p icture of how some o f th e inform ation on w h at is happening in G erm any has been obtained. Of course, we all becam e soldiers for the tim e being; we w ent over to G erm any a n d were on th e ta rg e ts w ithin a few hours of th e ir capture. I t was a ru sh job, because th e assau lt on the R u h r was v ery rap id once it did sta rt.
Ma j o r Go r d o n, in presenting th e following p ap er, said : D r P a rk e r has given an indication of th e conditions in w hich we exam ined th e various plants in G erm any, an d I would ta k e th e o p p o rtu n ity to say w h at a v ery fine team of people was provided by th e au th o rities concerned to m ake up these various m issions in to G erm any. T he position was a little com plicated in t h a t th e investigation of th e ta rg e ts was a jo in t effort w ith th e Americans.
B u t I m u st say t h a t I found th e A m ericans v ery easy to g et on w ith ; th e leader of th e ir p a rty , m y various colleagues an d I found no difficulty in co-operating an d arranging who should go to which places, on th e same so rt of plane, th o u g h in a sm all way, as t h a t on w hich G enerals M ont
gom ery and Eisenhow er arranged who should be w hat.
Reference was m ade b y D r P a rk e r to th e docum ent w hich gives a sum m ary of th e inform ation contained in th e re p o rts w ritte n b y the leaders o f th e various team s. A g re at deal of tim e h a d to be devoted to it in order to m ake everything co n sisten t; a n d i t is a v e ry large docu
m ent. I do n o t know w h at th e S tatio n ery Office will charge for it, b u t it is w orth a lo t o f m oney, I th in k . I rea d th e final proofs ab o u t a m onth ago.
W hen I was asked b y th is I n s titu te to p rep are a p a p e r on th e same subject it was ra th e r difficult for me, as you will ap p reciate, to go over th e sam e ground again. So th a t, ra th e r th a n fill th is p a p er w ith detailed scientific an d sta tistica l inform ation, which would have m ade it v ery long, an d having regard to th e fa c t th a t th e detailed re p o rt is being pubhshed, I felt th a t a brief sum m ary of th e position in G erm any would be m ore acceptable and perhaps easier to read, draw ing th e a tte n tio n o f those in te rested to th e various things th e y m ight like to follow u p w hen th e detailed re p o rt is available.
F rom th e p o in t of view o f pure fuel technology we were all "very d is
4G 8 GORDON : D E V EL O PM E N T OF H Y D R O G EN A TIO N AND
FIS C H E R -T R O P S C H PRO CESSES IN G ERM A N Y . 4 6 9 appointed th a t n o t more knowledge was gained. So far as th e h y d ro genation process was concerned, of which I had a knowledge before th e war of w hat was going on in G erm any, the developm ents were com pletely negligible in th e direction of new processes; there was th e developm ent of an enorm ous num ber of new plants, b u t there was no really new inform a
tio n beyond th a t w hich was know n in 1938. I th in k th e sam e rem ark applies to th e F ischer-T ropsch process. I am n o t so fam iliar w ith th a t, b u t so far as I could m ake o u t th ere was really nothing new, and there was n o t in th a t case th e very big developm ent o f o u tp u t th a t h ad been effected in hydrogenation. In stra ig h t oil refining th ere was ever^ less.
There were some interesting developm ents of petroleum production in G erm any, th e G erm ans having found some new fields; th a t m a tte r is d ealt w ith in th e report. There was also a very g reat deal of interesting chemical developm ent on th e border-line betw een petroleum technology and th e chemical in d u stry ; some of th a t developm ent is dealt w ith a t greater length in th e report.
DEVELOPMENT OF- HYDROGENATION AND FISCHER-TROPSCH PROCESSES IN GERMANY.
By K . Go r d o n;*
Ge n e r a l.
Th e hydrogenation process was th e more im p o rtan t of th e tw o synthetic processes used in G erm any from th e point of view of th e production of fuel.
The first commercial p lan t was b uilt a t Leuna, and it was started in 1927.
I t was originally intended to operate w ith brown coal, b u t various diffi
culties caused this p lan to be abandoned tem porarily, and brown coal-tar was th e raw m aterial used u n til 1931, when th e difficulties w ith brow n coal were overcome.
B y th e o utbreak of w ar th e o u tp u t a t Leuna h ad reached 440,000 tons a year, and during th e war th e o u tp u t increased to 600,000 tons a year.
The building of new hydrogenation plants was an im p o rtan t p a rt of the five-year p lan which was p u t into operation a t th e access of th e Nazis to power. The first plan ts were a t Bohlen and Magdeburg, and were combined brow n coal carbonization and brow n coal-tar hydrogenation plants. These plan ts added 300,000 tons a year to the' capacity for hom e-produced oils in Germ any.
The first p lan t built in G erm any for th e hydrogenation of bitum inous coal was a t Scholven. This p lan t was sta rte d up in 1937, and used a process sim ilar to th a t em ployed a t Billingham.
A t th e outbreak of th e w ar th e capacity of th e plan ts com pleted was 1,400,000 tons a year, and actual o u tp u t was a t th e rate of over 1,000,000 tons a year. More new plants were built, u n til th e capacity of th e installed plan ts wfts ab o u t 4,000,000 tons a year. The actu al o u tp u t reached a m axim um ra te corresponding to 3,600,000 tons a year early in 1944, when Allied bom bing rapidly reduced production to a negligible am ount.
* Im p e ria l C hem ical In d u s trie s , L td .
4 7 0 G O R D O N : D E V E L O P M Ei i j. u i H Y D R O G E N A T I O N A N D
The hydrogenation p lan ts were th e m ost im p o rta n t of th e G erm an sy n th e tic fuel p la n ts, as th e y provided th e whole of G erm any’s requirem ents of av iatio n f u e l; nearly h alf th e o u tp u t of the hydrogenation p lan ts was ta k e n in th is form.
The first p la n t em ploying th e Fischer process was s ta rte d by R uhrchem ie in 1936. In 1939 th e ra te d capacity of th e F ischer p la n ts was 740,000 to n s a year. There was little or no increase in th is capacity during th e w ar. The m axim um o u tp u t of th e Fischer p la n ts was a t a ra te of 570,000 to n s a year, some 14 per cent of th e to ta l production of oil from coal.
T he reason for th e lack of developm ent of th is process com pared w ith progress in hydrogenation is n o t difficult to find. The m otor fuel produced is of very poor q u ality from th e p o in t of view of octane num ber, and is quite u n su itab le for av iatio n fuel. T he principal in te rest in th e Fischer process was its use for supplying raw m aterials for chem ical processes, a n d th e pre-w ar scale of operation was am ple to supply all th e requirem ents in th is field.
Table I, which is ex tra c te d from th e “ R e p o rt on S tu d y of L iquid Fuel Processes in G erm any,” sh o rtly to be published, gives a sum m ary of the c a p acity for which th e various processes were installed.
Ta b l e I .
A n n u a l r a te o f p ro d u c tio n , to n s.
H y d r o g e n a tio n .
F is c h e r - T ro p sc h s y n th e sis
p la n ts .
R e fin in g o f G e rm an p e tro le u m .
B ro w n c o al a n d b it. coal- t a r d is tilla tio n .
B enzol. T o ta l
A v ia tio n fu e l . M o to r sp irit D ie se l oil F u e l oil . L u b r ic a tin g oil.
M iscellan eo u s .
1,900,000 350.000 680.000 240,000
40.000 40.000
270.000 135.000
20,000
160.000
160,000 700.000 70.000 780.000 90.000
35.000
110,000
750,000 50.000
50,000 330,000
1.950.000 1.145.000 1.625.000 1.060.000 840.000 340.000
3,250,000 585,000 1,800,000 945,000 380,000 6,960,000
Pr o d u c t i o n o e Sy n t h e s i s Ga s.
Synthesis gas is th e te rm used for a m ix tu re of carbon m onoxide and hydrogen which is needed for th e Fischer process directly or for th e p ro duction of th e pure hydrogen required for th e h y drogenation process. To m ake 1 to n of Fischer p ro d u ct we need 11,000 m 3 of synthesis gas. To m ake 1 to n of m otor fuel by th e hydrogenation process we need from 1000 to 3600 m 3 of hydrogen, a n d hence synthesis gas, according to th e raw m aterial used, and th e p ro d u ct m ade.
Coal Gasification.
Considering first of all a situ a tio n as in G erm any w here some form of coal is th e only raw m aterial, one is faced w ith th e in itial problem of gasi
fication. The Fischer and th e hydrogenation processes only differ in th is
FIS C H E R -T R O P S C H PRO CESSES IN GERM ANY. 4 7 1
respect in degree. I t is n o t proposed in this paper to give details of th e various types of p la n t used. A large proportion of th e o u tp u t was m ade in conventional w ater-gas p lan ts. Most of th e developm ents were in th e direction of th e utilization of low grade solid fuel as th e raw m aterial for gasification. Oxygen was used b o th for this purpose and to m ake the process continuous.
Manufacture of Hydrogen from Hydrocarbons.
The developm ent of processes, startin g w ith hydrocarbon gas as th e raw m aterial, is of m ore interest to th e oil industry. The first commercially operated p lan ts for th e production of hydrogen from n a tu ra l gas cracked th e n a tu ra l gas therm ally over red-hot brickw ork to give “ reform ed gas,”
n o t dissim ilar in composition to coke-oven gas. The hydrogen in 'th is gas was th en separated by liquefaction and distillation, em ploying th e f?ame process as is used to separate hydrogen from coke-oven gas.
A m ore a ttra c tiv e process was discovered by th e I.G . F arbenindustrie, an d was employed on a large scale for th e first tim e b y th e S tan d ard Oil Com pany A This goes b y th e nam e of th e “ m eth an e-steam process.”
The gas is passed, together w ith steam , over a cataly st containing nickel, and th e hydrocarbons are converted alm ost entirely to CO, C 0 2, and H 2.
There were considerable developm ents of this process by th e I.C .I. in E n g land. D etails of th e plan ts have recently been described in a paper by the w riter to th e In s titu te of Fuel entitled “ Developm ents in th e H ydrogena
tion of Coal and T a r.”
Two p lan ts were b uilt in G erm any during th e war, one a t Wesseling on th e R hine, an d one a t Polifz, near S te ttin . The Wesseling p la n t was very sim ilar to those b uilt in G reat B ritain, and it does n o t call for any special com m ent. The raw m aterial was th e ta il gas from th e hydrogenation p ro cess, and producer gas m ade from brow n coal b riq u e tte s was used as th e fuel.
The hydrocarbon gas is first purified from sulphur com pounds by passing a t 420° C through cham bers filled w ith iron oxide and zinc oxide. The reaction tem p eratu re is 750° C. The reaction is carried out in tubes in parallel m ade of K ru p p ’s NCT6 alloy’. The exit gas, after cooling in h eat exchangers, goes over an iron chrom ium cataly st a t a lower tem perature for th e conversion of th e m ajor p a rt of th e CO to C 0 2 and H 2 by catalysis w ith steam .
K W Process. ^
A lthough th e m eth an e-steam process is a t th e same tim e simple in operation and low in capital cost, th e Germans developed another process, know n as th e “ K W Process,” for th e m anufacture of synthesis gas from hydrocarbons. This process was developed a t Oppau and it was intended to operate it on a much larger scale a t new p lan ts a t H eidebreck, Walde- burg, Ausschwitz, and Linz. The h e a t of reaction for th e conversion of th e hydrocarbons to synthesis gas is provided by com bustion of p a rt of th e gas w ith oxygen.
T he reactions taking place in th e m ethane-steam process can be represented by :—
CH4 + H 20 = CO + 3H 2.
The hydrogenation p lan ts were th e m ost im p o rta n t of th e G erm an syn
th e tic fuel p lan ts, as th e y provided th e whole of G erm any’s requirem ents of aviation fu e l; nearly h alf th e o u tp u t of th e hydrogenation p lan ts was ta k e n in th is form.
The first p la n t em ploying th e Fischer process was s ta rte d by Ituhrchem ie in 1936. In 1939 th e ra te d capacity of th e Fischer p la n ts was 740,000 to n s a year. There w as little or no increase in th is capacity during th e w ar. T he m axim um o u tp u t of th e Fischer p lan ts was a t a ra te of 570,000 to n s a year, some 14 per cent of th e to ta l production of oil from coal.
The reason for th e lack of developm ent of th is process com pared w ith progress in hydrogenation is n o t difficult to find. The m otor fuel produced is of very poor q u ality from th e p o in t of view of octane num ber, and is q uite u n su itab le for av iatio n fuel. The principal inte rest in th e Fischer process was its use for supplying raw m aterials for chem ical processes, an d th e pre-w ar scale of operation was am ple to supply all th e requirem ents in th is field.
T able I, which is ex tra c te d from th e “ R ep o rt on S tu d y of Liquid Fuel Processes in G erm any,” sh o rtly to be published, gives a sum m ary of th e c a p acity for which th e various processes were installed.
4 7 0 G O R D O N : D EV EL O PM E N T OY .
Ta b l e I.
A n n u a l r a te o f p ro d u c tio n , to n s.
H y d r o g e n a tio n .
F is c h e r - T ro p sc h sy n th e sis
p la n ts .
R efin in g o f G e rm an p e tro le u m .
B ro w n c o al a n d b it. coal- t a r d is tilla tio n .
B enzol. T o ta l
A v ia tio n fu el . M o to r s p irit D ie se l oil F u e l oil . L u b ric a tin g oil.
M iscellan eo u s .
1,900,000 350.000 680.000 240,000
40.000 40.000
270.000 135.000
20,000
160.000
160,000 700.000 70.000 780.000 90.000
35.000
110,000
750,000 50.000
50,000 330,000
1.950.000 1.145.000 1.625.000 1.060.000 840.000 340.000
3,250,000 585,000 1,800,000 945,000 380,000 6,960,000
Pr o d u c t i o n o f Sy n t h e s i s Ga s.
Synthesis gas is th e term used for a m ix tu re of carbon m onoxide and hydrogen which is needed for th e Fischer process directly or for th e p ro duction of th e pure hydrogen required for th e h y d rogenation process. To m ake 1 to n o f Fischer p ro d u ct we need 11,000 m 3 of synthesis gas. To m ake 1 to n of m otor fuel by th e hydrogenation process we need from 1000 to 3600 m 3 of hydrogen, a n d hence synthesis gas, according to th e raw m aterial used, an d th e p ro d u ct m ade.
Coal Gasification.
Considering first of all a situ atio n as in G erm any w here some form of coal is th e only raw m aterial, one is faced w ith th e in itial problem of gasi
fication. T he Fischer and th e hydrogenation processes only differ in th is
FIS C H E R —TROPSCH PROCESSES IN GERMANY. 47 1 respect in degree. I t is n o t proposed in this paper to give details of the various ty p es of p la n t used. A large proportion of th e o u tp u t was m ade in conventional w ater-gas p lan ts. M ost of th e developm ents were in th e direction of th e utilization of low grade solid fuel as th e raw m aterial for gasification. Oxygen was used b o th for this purpose and to make the process continuous.
Manufacture of Hydrogen from Hydrocarbons.
The developm ent of processes, startin g w ith hydrocarbon gas as th e raw m aterial, is of more in terest to th e oil industry. The first commercially operated p lan ts for th e production of hydrogen from n atu ra l gas cracked th e n a tu ra l gas therm ally over red-hot brickw ork to give “ reformed gas,”
n o t dissim ilar in com position to coke-oven gas. The hydrogen in 'th is gas was th en separated b y liquefaction and distillation, employing th e iam e process as is used to separate hydrogen from coke-oven gas.
A more a ttra c tiv e process was discovered by th e I.G. Farbenindustrie, a n d was em ployed on a large scale for th e first tim e by th e S tandard Oil C om pany This goes by th e nam e of th e “ m ethane-steam process.”
The gas is passed, together w ith steam , over a cataly st containing nickel, an d th e hydrocarbons are converted alm ost entirely to CO, C 0 2, and H 2.
There were considerable developm ents of this process by th e I.C .I. in E n g land. D etails of th e plan ts have recently been described in a paper by th e w riter to th e In s titu te of F uel entitled “ D evelopm ents in th e H ydrogena
tio n of Coal and T a r.”
Two p lan ts were b uilt in G erm any during th e war, one a t Wesseling on th e R hine, an d one a t Polifz, near S tettin . The Wesseling p lan t was very sim ilar to those b u ilt in G reat B ritain, and it does n o t call for any special com m ent. The raw m aterial was th e ta il gas from th e hydrogenation p ro cess, and producer gas m ade from brow n coal b riq u e tte s was used as the fuel.
T he hydrocarbon gas is first purified from sulphur com pounds by passing a t 420° C through cham bers filled w ith iron oxide and zinc oxide. The reaction tem p e ratu re is 750° C. The reaction is carried out in tubes in parallel m ade of K ru p p ’s NCT6 alloy'. The exit gas, after cooling in heat exchangers, goes over a n iron chrom ium cataly st a t a lower tem perature for th e conversion of th e m ajor p a rt of th e CO to C 0 2 an d H 2 by catalysis w ith steam .
K W Process. v
Although th e m eth an e-steam process is a t th e same tim e simple in operation and low in capital cost, th e Germ ans developed another process, know n as th e “ K W Process,” for th e m anufacture of synthesis gas from hydrocarbons. This process was developed a t Oppau and it was intended to operate it on a m uch larger scale a t new plan ts a t H eidebreck, Walde- burg, Ausschwitz, an d Linz. The h e a t of reaction for th e conversion of the hydrocarbons to synthesis gas is provided by com bustion of p a rt of th e gas w ith oxygen.
T he reactions taking place in th e m e th an e-steam process can be represented by :—
CH4 + H 20 = CO + 3H 2.
4 7 2 GORDON : D E V EL O PM E N T OF H Y D R O G EN A TIO N AND
The reaction is endotherm ie, a n d th e am o u n t of fuel required co rre
sponds to 37 per cent of th e calorific value of th e reacting gas.
In th e K W process th e re a c ta n t gas and oxygen are preheated an d burned a t high te m p eratu re ; th e h o t gases pass directly over a nickel-containing cataly st. T he overall reactio n can be represented as follows :—
CH4 + i 0 2 = CO + 2 H 2.
I t will be seen th a t th e gas produced is th ree-q u a rters of th a t m ade by th e m eth a n e-steam process. As no ad d itio n al fuel is required, th e overall h eat balances of th e tw o processes are very sim ilar. T he K W process requires oxygen which involves cap ital expenditure an d running costs.
Considerable precautions are necessary to avoid explosions in th e burner.
B ecause of th e high te m p eratu re a t w hich th e gases leave th e b u rn er and pas's to th e nickel cataty st, 1200° C, nickel is lost as carbonyl and has to be replaced b y introducing nickel n itra te in th e com bustion zone. Again on account of th e high tem p eratu re, th e re is a sm all form ation of carbon in th e form of soot an d th is has to be filtered from th e ex it gas.
To give a proper com parison of th is process w ith th e m eth an e-steam process a n accurate economic s tu d y u n d er com parable, conditions would have to be m ade, b u t it is difficult to see w h at benefit th e K W process offers over th e m e th an e-steam process. A possible reason for its adoption is to avoid th e use of high chrom ium steel for reaction tu b es, as th is m aterial w as in sh o rt supply in G erm any during th e war.
Modification of the K W Process to Produce Acetylene.
A very interesting m odification of th e K W process was in th e pilot p la n t stage in G erm any. O xygen was b u rn ed in th e hydrocarbon gas in a sim ilar way to t h a t ju st described, b u t th e re a c ta n ts were preheated, the products were rap id ly cooled, an d no- c a ta ly st was used. Acetylene was produced in a pro p o rtio n approxim ating to th e equilibrium am o u n t a t th e high te m p eratu re of th e flame. N o steam is, of course, ad d ed to the reacting gases.
In cases w here b o th acetylene is required an d th e synthesis gas is needed for chem ical purposes an d n o t used as fuel, th e process app ears to offer some economic attrac tio n s. A pproxim ately 25 p er cent of th e carbon in the hydrocarbon gases is converted in to actylene, an d th e balance is recovered as synthesis gas.
The reaction can be represented very appro x im ately b y th e equation :—
7C2H 6 + 7 0 2 - 2C2H 2 + CH4 + C 0 2 + 8CO + 13H2 + 4 H 20 . Using m ethane as th e raw m aterial th e com position of th e ex it gas is :—
A c ety len e C arb o n dio x id e M eth an e
C arbon m o n o x id e H y d ro g e n
8 to 9 p e r c e n t.
3 to 4
6 to 7 ,,
24 to 26 ,, 56
A cetylene and also C 0 2 are rem oved from th e gas m ix tu re b y compression to 18 atm ospheres, an d washing w ith w ater. T he residual gas contains ra th e r more m ethane th a n is desirable for both processes requiring synthesis, gas, and a second stage tre a tm e n t would be desirable to rem ove it.
F IS C H E R -T R O P S C H PROCESSES IN GERMANY. 4 7 3 Operation of CO Conversion Under Pressure.
The only oth er notew orthy developm ent in th e production of synthesis gas was a pressure process for th e reaction :—
CO + H 20 - C 0 2 + H 2.
This process operated a t atm ospheric pressure has long been known and is th e conventional m ethod of hydrogen m anufacture for am m onia synthesis, for th e hydrogenation process, and for adjusting th e H 2 : CO ratio of gas for synthesis gas m anufacture. An increase of pressure has no effect on the equilibrium , b u t it increases th e velocity of reaction.
Since one volum e of CO gives by this reaction one volume of C 0 2 and one volum e o f-hydrogen, compression costs are saved by carrying out the hydrogen reaction a t as high a pressure as is practicable. I t is, on the o th er hand, necessary to use high-pressure steam instead of low-pressure steam for th e reaction.
In practice considerable difficulty was encountered by th e Germans in o perating th is process. W hilst an atm ospheric pressure p lan t can be b u ilt th ro u g h o u t of mild steel, an d no particu lar corrosion problem s are m et, th e use of high-pressure gases produces corrosion problem s which are only overcome b y th e use of stainless steel.
As is th e case w ith th e K W process, it would appear doubtful w hether th is process would in fact give a su b stan tial im provem ent over conventional m ethods.
Th e Hy d r o g e n a t i o n Pr o c e s s.
Table I I gives a list of th e G erm an hydrogenation plants, their capacity a n d th e raw m aterials em ployed :—
Ta b l e I I .
German H ydrogenation P la n ts Operating in 1945.
N am e o f p la n t. M ain raw m a te ria l.
N o m in al c a p a c ity for p ro d u c tio n o f to ta l
liquid p ro d u c ts in clu d in g liquefied
gas (to n s/y ear).
L eu n a . . . . B row n coal a n d bro w n co al-ta r 620,000
B o h len . . . . B row n c o a l-ta r 250,000
M agdeburg B ro w n c o a l-ta r 220,000
Z eitz . . . . B ro w n c o a l-ta r 250,000
Scholven B itu m in o u s coal 220,000
G elsenberg W elheim
B itu m in o u s coal 400,000
P itc h a n d t a r 130,000
P ö litz -S te ttin B itu m in o u s coal, p itc h , ta r , a n d p e tro leu m residues
700,000 L ü tz k e n d o rf . P e tro le u m resid u es a n d t a r 50,000
W esseling R h in e b ro w n coal 200,000
B rü x . B ro w n c o al-ta r 400,000
B lec h h am m er B itu m in o u s coal 425,000
Hydrogenation of Bituminous Coal.
The first p lan t for hydrogenating bitum inous coal was b uilt a t Billingham.
The first p la n t in G erm any was a t Scholven, and formed an addition to an
4 7 4 GORDON : D E V EL O PM E N T O r n r DRO GENATION AND
existing am m onia p lan t. The Scholven p la n t em ployed su b stan tially th e sam e process as was used a t Billingham , which has already been described.*
Coal is m ade into a 45 per cent coal p a s te ; tin oxide and am m onium chloride are added as catalysts. The reaction tak es place a t 460° C and 300 a tm pressure. The h o t products leaving th e m ain converter are neutralized w ith a suspension of alkali in oil to avoid corrosion through chlorine.
The th ro u g h p u t of coal a t Scholven was 0-264 to n s/m 3 reaction volum e/- hour. T he yield of m otor sp irit an d m iddle oil was 60 to 61 per cent of th e ash- a n d m oisture-free coal.
The sludge was tre a te d for oil recovery by fugalling an d carbonization in
“ kugelofen ” of th e residue.
L a te r, coal hydrogenation p lan ts were b u ilt a t Gelsenberg, a t Politz,
■near S te ttin , an d a t B lechham m er. In these p la n ts it was decided to raise th e reactio n pressure- a t 700 atm . All o th er conditions being k ep t constant, th e increased pressure w ould be expected to be accom panied by increase in yield an d decrease in th e reaction volum e required. The m ain purpose of th e increase in pressure in these p lan ts appears n o t to have been to o btain th is increased yield, b u t to sim plify th e operation by m aking unnecessary th e use of m axim um chloride an d th e subsequent n eu traliza
tio n of th e hydrochloric acid in th e vapours b y alkali. I t w ould indeed be im practicable to use th e acid hydrogenation conditions w ith am m onium chloride a t 700 a tm pressure, since condensation of hydrochloric acid would ta k e place even a t th e reaction te m p eratu re, a n d it w ould be impossible to avoid corrosion b y th e m eans ad o p ted a t 300 a tm pressure. A t 700 atm , 1-2 per cent of iron in th e form of sulphate, to g eth er w ith 1-5 p er cent by w eight of “ B ayerm asse ” (iron oxide), an d 0-3 per cent by w eight of sodium sulphide, was used as cataly st. A ra th e r higher te m p eratu re, 480° C in place of 460° C, was em ployed.
A t th e p la n ts a t Gelsenberg a n d Politz, coal hydrogenation was operated un d er approxim ately balanced .conditions, so far as th e production of heavy oil is concerned. The tem p eratu re an d th ro u g h p u t are controlled so th a t th e n e t form ation of heavy oil ju s t equals th a t lost in th e tre a tm e n t of the sludge.
A t B lechham m er there was a n interesting variatio n . A higher th ro u g h p u t was used, an d gave excess of heav y oil w hich was disposed of as a fuel, un d er conditions involving th e replacem ent of p a r t of th e heav y oil used for preparing th e coal p aste by m iddle oil.
I t was th e original in ten tio n of th e B illingham p la n t to o p erate th e coal hydrogenation stage in a sim ilar w ay, b u t th e object w as n o t to m ake fuel oil, b u t to allow th e heavy oil to be tre a te d u n d er m ore efficient conditions in a separate liquid-phase hydrogenation stage. O peration w ith excess of heav y oil h a d to be abandoned because a t th e pressure em ployed th ere was an excessive accum ulation of asp h alts in th e circulating heav y oil system . O peration a t 700 a tm rem oves th is lim itation.
Table I I I gives th e operating conditions of th e coal stage a t Scholven
* G ordon, K „ “ T h e D ev elo p m en t o f C oal H y d ro g e n a tio n b y Im p e ria l C hem ical In d u s trie s , L td .,” J . In s t. F uel, 1935, 9, 6 9 ; G o rdon, K ., “ P ro g re ss in th e H y d ro g e n a tio n o f Coal a n d T a r ,” J . In s t. F u el, 1946, 20, 42,
F IS C H E R -T R O P S Ç H PROCESSES IN GERMANY.
Ta b l e I I I .
Scholven. G elsenberg. B lechham m er.
O p e ra tin g p re ssu re , a tm o sp h e re s 300 700 700
Coal fe ed r a te , t o n /m 3/h o u r 0-264 0-39 0-65
H y d ro g e n u se d , p e r c e n t .
Y ield o f m o to r fu el p lu s m id d le oil, 9 to 10 10-3 8
p e r c e n t . . . . . 61 66-8 46-7
F u e l oil, p e r c e n t . . . . ni l ni l 21-5
U n c o n v e rte d coal, p e r c e n t 8 4 4
L oss o f oil, p e r c e n t 6-0 4-7 5-5
H y d ro g e n gases, p e r c e n t 25-0 20-5 29 to 20
an d a t Gelsenberg (these figures apply equally to Pölitz) and a t Blech ham m er.
The m otor fuel and middle oil were th en hydrogenated together by th e vapour phase process, to be described later. In this way, separate acid tre a tm e n t of liquid-phase m otor fuel was avoided.
Hydrogenation of Middle-German Brown Coal.
This m aterial was th e first to be hydrogenated on a commercial scale an d th e process was operated a t L euna in th e first instance in 1927. As . already indicated, this operation ceased for a tim e b u t was restarted in 1931,
an d continued thereafter.
The operating pressure a t L euna is 230 atm , and th is pressure was doubtless chosen to be in line w ith conditions em ployed for am m onia synthesis. A higher pressure is preferable, a n d in th e brown coal p lan t b u ilt a t W esseling th e pressure was increased to 700 atm . The raw m aterial used in th is p la n t differed from m iddle-G erm an brown coal in being a m ore refracto ry m aterial.
The d ry brow n coal was m ade into a paste w ith heavy oil an d “ B ay er
masse ” was added as th e cataly st, in a concentration of 4 per cent by weight on th e original coal. The p aste contained 44 per cent coal and was hydrogenated w ith tem p eratu res up to 490° C. Im proved results were obtained by dropping th e tem p eratu re of th e last converter of th e series to 475° C.
O perating conditions w ith brown coal a t L euna are given in Table IV.
Ta b l e IV .
P re ssu re . . . . . 230 a t m
T h ro u g h o u t . . . . . 0-46 to n /m
Y ield o f m o to r fuel p lu s m id d le oil . 50 p e r c en t
H y d ro c a rb o n gases 15-2 „
CO a n d C 02 . . . . . 10-6 „
U n c o n v e rte d coal . . . . 1-5 „
H y d ro g e n ab so rb ed 6-7 „
Hydrogenation of Brown Coal-Tar.
Brow n coal-tar is a m uch more reactive and a lighter boiling m aterial th a n ta r from bitum inous coal. On th e plants a t Bohlen, M agdeburg, Leuna, and B riix, the crude ta r was first fugalled to remove solids, and then distilled into m iddle oil, for tre a tm e n t in th e vapour phase, and a heavy oil residue. The la tte r was hydrogenated a t pressures in th e region of
4 7 6 GORDON : D E V EL O PM E N T OF H Y D R O G EN A TIO N AND
220 to 300 a tm a t a tem p eratu re of 460 to 480° C using as th e c a ta ly st finely divided brow n coal coke im pregnated w ith iron. T he am o u n t em ployed was 1 per cent of cataly st, containing 5 to 6 per cent of iron, on th e ta r.
The feed ra te was ap proxim ately 1 to n /m 3/hour, th e yield of m otor fuel plus m iddle oil appro x im ately 79 per cent, and th e hydrogen consum ption 3-8 per cent.
The products leaving th e converter were sep arated in a catch p o t m ain tain e d su b stan tially a t reaction tem p e ratu re, and th e liquid heavy oil recycled th ro u g h th e p reh ea ter to th e first converter. P a r t o f it m ust be let down in pressure continuously, to rem ove th e accum ulation of ash in th e system . The purge is carbonized in sim ilar ro ta ry kilns to those used for coal hydrogenation p roduct. T he lighter products go overhead from th e h o t catch p o t an d are condensed in th e coolers.
A fter separation from excess hydrogen, th e pressure is released in stages.
Th* p ro d u ct is norm ally distilled in th e sam e p la n t as t h a t em ployed for th e distillation of th e crude ta r into m iddle oil and heavy oil. The la tte r is
The m iddle oil from th e liquid-phase hydrogenation a n d th e m iddle oil obtained directly by th e d istillation of ta r were hydrogenated to g eth er in the vapour phase. L ight oil recovered from th e gases from brow n coal car
bonization was also included in th e feed to th e vapour phase.
The overall yield in th e process from crude ta r was 75 to 85 per cent by w eight of m otor spirit to ab o u t 70 per cent of av iatio n spirit.
A t Zeitz th ere was an in terestin g v ariatio n of brow n coal-tar h ydro
genation. The ta r, afte r fugalling a n d filtering, was fed to converters filled w ith p elletted 5058 (tungsten sulphide) cataly st, a t 300 a tm an d tem pera
tu res of 360 to 390° C.
The p ro d u ct is m ore s a tu ra te d th a n th a t o btained by norm al o p e ra tio n ; indeed a t th e lower te m p eratu re some 10 per cent of lubricating oil base was obtained. The m ain pro d u ct was diesel oil in a yield of 50 to 60 per cent.
Hydrogenation of Bituminous Coal-tar, Pitch, and Petroleum Residues.
These m aterials are all more refra cto ry th a n brow n coal p ro d u cts which form ed such a large p a r t o f G erm an production, an d were tre a te d a t 700 a tm a t S te ttin , W elheim , a n d L utzkendorf. T he process is th e same as th a t described from brow n coal-tar, except for th e increase of pressure, an d an increase of reactio n tem p e ra tu re from 480 to 490° C. The cataly st was th e sam e as t h a t used for brow n coal-tar.
The W elheim p la n t was of in te rest in having been b u ilt in th e first place to tr e a t coal e x tra c t m ade b y th e P o tt Broche process. Difficulties w ith th is process led to th e p lan ts being op erated on pitch.
W elheim was s ta rte d before th e w ar, a n d was th e first hydrogenation p la n t to w ork a t 700 atm . The conditions for p itc h h y d rogenation a t W elheim are given in Table V.
recycled.
Ta b l e V.
O p e ratin g p re ssu re . . . F e e d r a te . . . . H y d ro g e n u sed
Y ield o f m o to r fuel p lu s m iddle oil Y ield o f fuel oil
700 a tm .
0-51 to n /m 3/h o u r 7-1 p e r c e n t 28
45 9 Y ield o f h y d ro c a rb o n gases
F IS C H E R —TROPSCH PROCESSES IN GERMANY. 4 7 7 A ccording to inform ation supplied by th e I.G ., a com bination of pitch hydrogenation a t 700 a tm w ith hydrogenation of th e middle oil resulting from th is operation an d th a t arising from th e initial distillation of th e t a r , would give a final yield of 78 per cent of petrol w ith a hydrogen absorption of 13-7 per cent.
The 700-atm process was used a t S te ttin and L ützkendorf for th e h y d ro genation of residues resulting from petroleum cracking. N ot m uch infor
m atio n is available. The sam e c ataly st was used as for other liquid-phase hydrogenation processes. The feed ra te was 0-63 to n /m 3/hour, the hydrogen absorption 3-2 per cent, and th e yield of m otor fuel plus middle oil 86 p er cent.
The petroleum residues were those resulting from cracking operations.
Much im proved results would be obtained from more carefully controlled hydrogenation of residues from distillation, in which cracking has been reduced to th e m inim um .
F ajior-Phase Hydrogenation. >
' The survey of th e process as so far described for th e tre a tm e n t of coal, ta r, an d sim ilar m aterials, has consisted of a com bination of distillation and liquid-phase hydrogenation, giving as th e products middle oil, m otor fuel, an d hydrocarbon gasës. The first tw o were n o t norm ally separated in G erm an practice.
The specification for th e middle oil was fixed 4>y th e requirem ents of vapor-phase hydrogenation and norm ally calls for an end point of 325° C.
V apor-phase hydrogenation is usually carried out a t 250 to 300 atm pressure. There is norm ally no po in t in th e higher pressures th a t have been used for liquid-phase hydrogenation. A t W elheim and L ützkendorf, however, vapor-phase hydrogenation was worked a t 700 atm . The reaction tem p eratu re was usually in th e region of 400° C.
The oil was pum ped to th e required pressure and m ixed im m ediately w ith hydrogen a t th e same pressure. The proportion was usually 2000 m3/to n of oil. The m ixture of oil and hydrogen passed through tu b u lar h eat exchangers an d th e n through a gas-fired or electrically heated tu b u lar preheater. A u n it m ay comprise one, tw o, or three converters in series, a n d each converter is divided into com partm ents. E ach com partm ent is filled w ith solid p elletted or ex truded catalyst, and th e hydrogen and vaporized oil flow dow nwards over th e catalyst. Between each two sec
tions of th e converter, cold hydrogen is introduced to control th e tem p era
tu re. On leaving th e last converter th e products are cooled, first in heat exchangers an d finally in a w ater cooler. The m ixed gaseous and liquid p ro d u cts from th e cooler go to a high pressure separation vessel where th e excess hydrogen is separated an d recirculated to th e plant.
The pressure is released, usually in th ree stages, to effect a degree of stabilization.
I n vapor-phase hydrogenation th e form ation of light hydrocarbon gases is sm all relative to th a t found in liquid-phase hydrogenation. The solu
b ility o f hydrocarbon gases in th e oil is such th a t th e concentration of hydrocarbon gases does n o t rise above 10 per cent. In th e liquid-phase, on th e other hand, it is usually necessary to pass circulating hydrogen
4 7 8 GORDON : D E V EL O PM E N T OF H Y D R O G EN A TIO N AND
through subsidiary colum ns, in which it is washed w ith circulating oil, to m ain tain th e hydrocarbon concentration dow n to a reasonable m axim um .
The original vapor-phase process was a single stage one. T he liquid p ro d u ct contained some 50 to 70 p e r cent of m otor fuel, an d was distilled to give th ree fractions, excess b u ta n e and lighter hydrocarbon gases, m otor fuel, a n d recycle m iddle oil. T he la st is re tu rn e d to th e process. The c a ta ly st introduced by th e I.G . in 1931 was tu n g ste n sulphide (5058). I t is extrem ely active, provided t h a t a m inim um concentration of sulphur is p resen t in th e to ta l feed m aterial. A n im provem ent was developed in 1935. This consisted of th e use of a c a ta ly st (6434) containing 10 per cent of tu n g ste n sulphide on a c tiv a te d e a rth . T his c a ta ly st is very active, gives a high yield, a n d works a t ra th e r lower te m p eratu re. I t is v ery sensitive to nitrogen com pounds, a n d w hen dealing w ith ra w m aterials derived from coal-tar, a n d th e like, it is necessary t h a t th e feed should have prelim inary hydrogenation.
As th e process was w orked in G erm any th e first vapor-phase stage was operated w ith 5058 cataly st, giving some 30 per cent o f m otor fuel.
The m iddle oil from th is stage, am ounting to nearly 70 per cent of th e feed, th e n w ent to th e 6434 u n it for final conversion to m otor fuel.
The yields obtained b y th e tw o-stage vapor-phase hydrogenation process varied from 95 per cent, in th e case of m otor sp irit containing b utane, dow n to some 80 per cent in th e case of av iatio n spirit, in which no b u ta n e is perm issible, an d w here th e end p o in t of th e sp irit is lower, so th a t a greater
^proportion of th e crude p ro d u c t m u st be recycled.
The to ta l average feed ra te w as in th e region of 0-8 to 1-0 to n s o f feed per cubic m etre of c a ta ly st p er hour. T he average size of converter contained 8 m 3 of cataly st, an d usually th ree w ere op erated in series.
The life of th e 5058 ca ta ly st was a t least one, an d freq u en tly tw o, years.
The 6434 cataly st also h a d a life of over a year, b u t care h a d to be ta k e n to m ain tain its a c tiv ity by excluding nitrogen com pounds b o th from th e liquid feed and th e circulating gas.
A t W elheim an d L iitzkendorf, vapor-phase hy d rogenation was carried out a t 700 a tm pressure. This enabled 6434 ca ta ly st to be used in a single stage operation a t L iitzkendorf. A t W elheim a special c a ta ly st operated a t a good deal higher te m p eratu re was used (480° C) to produce a highly arom atic m otor fuel. I n b o th these cases th e sp irit yields were lower and gas yields higher th a n norm al.
The properties of th e m otor fuel m ade depended upon th e raw m aterial an d Table V I gives rep resen tativ e figures.
Ta b l e V I.
R a w m a te ria l.
M o to r s p irit C .F .R . O c tan e
No.
A v ia tio n s p irit C .F .R . O c ta n e
N o. (C lear).
A v ia tio n sp irit le a d e d w ith T 15 c .c ./litre
(6-2 c.c/g al) C .F .R . CTctane
N o.
B ro w n coal 64 70 88
B ro w n c o a l-ta r 62 68 86
B itu m in o u s coal . 68 72 90
B itu m in o u s c o a l-ta r 69 .73 90
FIS C H E R -T R O P S C H PROCESSES IN GERMANY. 4 7 9 Hydroforming and Sim ilar Processes.
The knock ratin g of hydrogenation m otor spirit produced in G erm any for av iatio n use was im proved by one of two processes, of which th e object was to dehydrogenate th e six-ring naphthenes present to arom atic com pounds. The first process, which was operated a t Leuna and Moosbier- baum , was th e hydroform ing process, sim ilar to th a t employed on a large scale in U.S.A.
The c ata ly st .employed was am m onium m olybdate on alum ina, and th e feed m aterial was a n a p h th a w ith an initial boiling point of 90° C. The operating tem p eratu re was 510° to 520° C and th e pressure 15 atm . The gas was recycled an d th e cataly st needed revivification w ith air every 6 to 12 hours.
A more commonly em ployed process was th e so-called D .H .D . process, in which th e feed m aterial as before is a n ap h th a. The feed m ixed w ith re cycle gas containing hydrogen is h eated to 500° C and passes through three or four converters arranged in series w ith interm ediate heating coils.
The products after cooling by h ea t exchange to 300° C go through a final converter for separation of polym erizable components.
The operating pressure was ab o u t 75 to 80 atm . The cataly st was 8 to 10 per cent m olybdic acid on activ ated alum ina. C atalyst revivification in th e u n it was carried out approxim ately once per week.
The process gave a pro d u ct approxim ately 80 octane num ber, which could be raised to ra th e r over 90 by th e addition of lead. The process.in fact gave from petroleum an d brown coal raw m aterials a m otor fuel sim ilar to th a t which could be obtained directly from coal.
Fi s c h e r Pr o c e s s. General.
W hen CO an d H 2 rea ct together in th e presence of a suitable cataly st a t 200 a tm pressure, th e y combine to form m ethanol. The reaction is practically q u a n titativ e, an d by-products are negligible. B y m odifying th e cataly st, higher alcohols appear in th e product, b u t in th e lim it n o t more th a n 30 per cent of th e pro d u ct is in this form. The form ation of these higher alcohols is accom panied by undesirable side reactions betw een th e CO an d H 2 to give m ethane and w ater.
W hen th e CO an d H 2 react a t atm ospheric pressure in .th e presence of catalysts of w hich th e active ingredient is a carbonyl-form ing m etal, a m ixture o f gaseous, liquid, and solid aliphatic hydrocarbons is form ed.
The reaction tem p eratu re is in th e region of 200° C and m ust be closely controlled.
The first commercial u n it was sta rte d in 1935, an d by 1939 there were nine u n its b uilt in G erm any w ith a ra te d o u tp u t of 740,000 tons of oil a year.
As a resu lt of research w ork an interm ediate pressure process was devised operating in th e region of 5 to 15 atm . The products were som ew hat sim ilar to those of th e atm ospheric process, b u t th ere was a tendency tow ards alcohol form ation.
The p lan ts in operation were w orked w ith a cobalt catalyst. There was a good deal of developm ent work on iron catalysts, b u t no large-scale operation.
D uring th e w ar th ere was no increase in Fischer p la n t o u tp u t, although research w ork continued u n ab ated . The m ajor p a r t played b y th e F ischer plan ts in th e G erm an w artim e econom y was th e p roduction of raw m aterials for chemical m anufacture.
Synthesis Gas Production.
W hilst in th e hydrogenation process, only a p a r t of th e to ta l coal -con
sum ption has to be gasified to give th e necessary hydrogen, in th e Fischer process th e whole of th e raw m aterial m u st be tu rn e d in to a m ix tu re of CO an d H 2.
The Fischer p la n ts in G erm any em ployed a conventional w ater-gas process using coke as th e raw m aterial. T he ra tio of H 2 a n d CO, which are required in th e p ro p o rtio n of 2 : 1, was ad ju ste d eith er by reactio n w ith steam over a c a ta ly st to convert p a rt of th e CO to C 0 2 a n d H 2, or by in tro ducing coke-oven gas to th e w ater-gas generator.
I t is necessary t h a t th e synthesis gas be highly purified, an d th e p ro cedure was first to apply th e conventional m ethod of rem oving HgS w ith iron oxide. The n e x t step was to rem ove th e organic sulphur by passing th e gas th ro u g h tow ers containing granules o f a m ix tu re of iron oxide and soda. The p u rity of th e final gas varied from 0-05 to 0-2 gm of sulphur per 100 m3.
Fischer Synthesis.
The c ataly st em ployed was a m ix tu re of cobalt, th o riu m oxide, m ag
nesium , an d kieselguhr, in th e ra tio of 100 : 5 : 8 : 200.
Before p u ttin g to use, th e c a ta ly st is reduced w ith hydrogen a t ab o u t 400° C to give a 60 per cent reduction of th e cobalt to th e m etallic state.
The design of p la n t to carry o u t th e synthesis reaction presents con
siderable chem ical engineering difficulties. There is a very considerable cataly st volum e, as th e o u tp u t of oil is only 0-008 to n s p er m 3 per hour, com pared w ith 0-5 per m 3 p er hour for vapor-phase hydrogenation. The h e a t of reaction is v ery g reat, app ro x im ately 600 kilocalories/m 3 synthesis g a s ; in fact, approxim ately o ne-quarter of th e h e a t o f com bustion of the same gas. This g reat h e a t o f reaction m u st be rem oved w ith o u t p erm ittin g a rise of tem p eratu re th ro u g h th e ca ta ly st of m ore th a n ab o u t 10° C.
I f th e tem p eratu re is allowed to become excessive, th e n oth er reactions set in, such as th e form ation of m eth an e an d carbon.
This difficulty in rem oving th e h e a t is accen tu ated b y th e fa c t th a t th e process is operated a t atm ospheric pressure. A t higher pressures, th e greater h ea t conductivity of th e gas m akes th e problem easier, an d it was doubtless largely for th is reason th a t th e G erm ans developed th e m edium -pressure process.
In th e p lan ts designed for atm ospheric pressure, th e reactio n vessels were rectan g u lar steel cham bers, 5 m etres by 2-5 m etres b y 1-5 m etre, containing horizontal tubes cooled by circulating w ater connected u p to a steam drum . To increase th e h e a t tra n sfe r surface, th e tu b es were ex pan d ed into vertical steel plates, and th e c a ta ly st was packed in th e spaces betw een them .
Control of th e pressure in th e steam drum gives control of th e tem p era tu re o f th e reaction.
4 8 0 GORDON : D E V ELO PM EN T C“ ...
F IS C H E R -T R O P S C H PR O C ESSES IN GERM ANY. 4 8 1
I n th e case of th e m edium -pressure process, working a t about 10 atm , a vertical cylindrical vessel was em ployed with tubes containing th e c a ta ly st expanded an d welded between two tu b e plates. Generally, in place of th e simple design of single tubes, concentric tubes were employed, w ith w ater a t each side of th e cataly st space.
In operating th e atm ospheric-pressure process, th e gas passes through tw o sets of reaction vessels in series. A rrangem ents were m ade so th a t a suitable num ber of vessels could perm anently be off-stream for re a ctiv a
tio n , or replacem ent of catalyst.
T he new ly charged vessels were placed first on-stream in th e second stage, a n d th e n transferred to th e first stage.
T he to ta l cataly st life varied from 4 to 8 m onths. New cataly st would be p u t into operation a t a te m p eratu re of 180° to 185° C, and th e tem p era
tu re g radually increased to 200° C.
The cataly st was from tim e to tim e revivified in situ by washing w ith oil or b y tre a tm e n t w ith hydrogen, or both, w ith th e object of rem oving high m olecular weight hydrocarbons on th e catalyst.
O peration w ith th e m edium -pressure process was generally carried o u t in th ree stages a t a pressure of 10 atm . Sim ilar arrangem ents were em ployed for tre a tm e n t of th e catalyst.
Ta b l e V II.
C om parison o f A tm ospheric an d Pressure Fischer Synthesis.
W o rk in g p re ssu re , a tm o sp h e re s . . . . 1 10
H 2/CO ra tio o f gas : S tag e 1 . 2 : 1 1-5 : 1
„ 2 ... 2 : 1 1-6 : 1
„ 3 ... 2 : 1 1-8 : 1
A verage gas r a te m3/h r/re a c to r, a ll sta g e s 660 680
R e ac tio n te m p e ra tu re , ° C 180-200 180-200
C a ta ly s t v o lu m e, m3 . . . . . . 10 10
U sefu l p ro d u c ts (C3 a n d over), g m /m3 gas 150 155,
„ ,, ,, ,, k g m /h r/re a c to r . 81 87
k g /h r /m3 c a ta ly s t 6-75 8-7
,, ,, ,, ,, to n s /y e a r/re a c to r 650 700
Shape o f vessel . . . . . . . re a c ta n g u la r cy lin d rical
D im ensions, m e tre s . . . . 5 X 2-5 X 1-5 6-9 x 2-7 dia.
N u m b e r o f tu b e s , 600 2,100
S urface o f tu b e s , m2 . . . . . 400 2,100
T o ta l cooling su rface, m2 . . . . . 4,000 2,100
H e a t p e r m3 g as c o n v erted , k .cals . . . . 600 600
H e a t p e r re a c to r p e r h o u r, to n n e cals 400 410
H e a t tra n s fe r, k .c a ls /m 2/h o u r 100 195
P roducts (% b y w eig h t o f to ta l) :
C3 a n d C4 . 14 (45) 10 (40)
L ig h t oil, 25-165° C . 47 (37) 25 (24)
M iddle oil, 165-230° C ... 17 (18)
H e a v y oil, 230-320° C . . . . . 11 ( 8) 38 (9)
S o ft w ax , 320-460° C . - . 8 15
H a r d w a x . . . . . . . 3 14
(F ig u res in p a re n th e s e s in d ic a te olefin c o n te n t o f fractio n .)
M otor F uel. O c tan e N o. (165° C E .P .) . 53 45
M id d le Oil. Solid p o in t . . . . . - 4 0 ° C —30° C
C e tan e N o. . *
} 78 55-48
