December, 1928
I-VDI;STRIAL , I N D E-VGINEERING CHEMISTRY
1341
Synthesis of Higher Hydrocarbons from Water Gas-11'" David F. S m i t h , Charles 0. Hawk, a n d D. A. Reynolds PITTSBURGHEXPERIMENT STATICIS,U. S. BUREAUOF ?VfINES, PITTSBURGH, PA.
T h e composition a n d m e t h o d of p r e p a r a t i o n of an active catalyst for the s y n t h e s i s of higher hydrocarbons f r o m water gas at a t m o s p h e r i c pressure have been described. T h i s catalyst at 203" C. will convert o n a single pass 18 per c e n t of t h e w a t e r g a s passed over it a t a space velocity of 230. At s o m e w h a t higher t e m p e r a t u r e s the conversion will be greater w i t h o u t giving a n appreciably larger fract i o n of m e t h a n e in the hydrocarbon products. R a t h e r complete i n f o r m a t i o n has been given o n t h e n a t u r e a n d a m o u n t s of the hydrocarbons formed a n d on the q u a n t i t i e s of water gas converted i n t h i s process when carried o u t u n d e r definite coiiditions of t e m p e r a t u r e a n d space velocity. M o s t of t h e oxygen appears i n t h e produ c t s as H20, t h e r a t i o H20:C02 increasing rapidly w i t h decreasing t e m p e r a t u r e . A t h i g h e r space velocities a n d at higher t e m p e r a t u r e s relatively m o r e u n s a t u r a t e d hydrocarbons are formed. At lower space velocities a n d a t higher t e m p e r a t u r e s , w i t h c e r t a i n limitations, relatively more heavier hydrocarbons a r e formed. T h e t o t a l hydrocarbon p r o d u c t s c o n t a i n f r o m a b o u t 20 weight per cent up of m e t h a n e , depending upon t e m p e r a t u r e a n d catalyst activity. W i t h a certain catalyst a t
260" C. and u s i n g a space velocity of a b o u t 260, the composition of the hydrocarbon p r o d u c t s is as follows:
HE synthesis of higher liydrocarboiis frcm water gas is perhaps of greatest practical interest to the gas industry, \There it presents the possibility either of converting off-peak gas into liquid fuel or of effecting enrichment and odorizatiori of blue water gas, a t such a time as increased cost of gas oil and other factors may make the process economical. Although enrichment of blue gas can as well be accomplished through converting it, by the relatively simpler process, into methane, t,he conversion to higher hydrocarbons has t'he advant'age oyer this in that there is the possibility not only of enriching but also of imparting the characterist,ic "gassy" odor to the blue gas and, further, of operating a combination process in which off-peak gas may be converted into liquid fuel. I n addition, this process, whereby even the solid hydrocarbons can be synthesized from carbon monoxide and hydrogen, is of considerable theoretical interest. That this reaction, in spite of its necessarily complicated mechanism, takes place so readily was a rather remarkable discovery. A great deal of work on this process has been done I)? its discoverers, Fischer and T r ~ p s c h . ~ However, complete and detailed account of their work has apparently not been published. A report of preliminary tests made in the U. S. Bureau of Mines was presented a t the Detroit meeting of the AMERICA&CHEJIICAL SOCIETY.~ Papers on
the subject have also been published by Elvins, Sash, and Erdely. I n the present work an attempt has been made to develop an active catalyst, to investigate its action and properties, and to determine the nature and amounts of the hydrocarbons produced and the amounts of water gas converted in this process. It was hoped that this work would provide useful. practical information and lead to a bdter understanding of the mechanism of the reactions involved.
T
1 Received July 2 5 , 1928. Presented before the Division of Gas and Fuel Chemistry at the 76th Meeting of the American Chemical Society, Swampscott, Mass., September 10 t o 14, 1928. * Published b y permission of the Director, U. S. Bureau of Mines. (Not subject to copyright.) 3 Ber., 69, 830, 832, 923 (1926); 60, 1330 (1927); Brcnnsrof-Chem., 4, 276 (1923); 7, 97 (1926); 9, 2 1 (1928); Fischer, I b i d . . 8 , 1 (1927); 8, 53 (1927); Fuel, 6, 89 (1927); Natl. Petvoleurn Seu's, 18, 49 (1926); Proc. International Conference on Bituminous Coal, p. 234 (1926), published by Carnegie Institute of Technology, Pittsburgh, Pa. 4 IND. ENG. CHEM., ao, 462 (192s).
Constituent Methane Enriching hydrocarbons ( G e r m a n "Gasol") M o t o r fuel
Weight per C e n t 21 45 34
More c o m p l e t e i n f o r m a t i o n o n t h e n a t u r e of the products m a y b e o b t a i n e d from the tables. Although i n most of the experiments a large fraction'of t h e hydrocarbon p r o d u c t s was u n s a t u r a t e d , itlis possible to reduce the proportion of u n s a t u r a t e s by u s i n g (1) lower space velocity, (2) lower t e m p e r a t u r e or a m o r e active c a t a lyst, (3) a reacting gas in which t h e r a t i o Hz:CO is higher (as has been shown by previous work). It is possible also, t o a certain e x t e n t at least, t o control the nature of t h e hydrocarbons produced as regards t h e i r molecular weight, by t h e choice of catalyst a n d by t h e t e m p e r a t u r e a n d space velocity used. The yields of hydrocarbons, exclusive of m e t h a n e , vary f r o m 92 t o 156 g r a m s per cubic m e t e r Hz CO converted. T h e r a t i o of Hz converted t o CO converted varies w i t h t h e experimental conditions. In the present work t h i s ratio varied f r o m 1.6 t o 2.0.
+
Apparatus a n d Experimental Procedure
TEMPERATURE CONTROL-Since
the reactions concerned are rather sensitive t o temperature and are highly exothermic, it is important to have a thermostatic control giving constant and uniform temperature and providing for rapid interchange of heat between catalyst and bath. As a bath liquid the eutectic mixture of sodium and potassium nitrates was used with enough lithium nitrate added t o bring the melting point down as required. This mixture is fluid and Clear and has excellent heat conductivity. The mixture melted a t about 130' C. and could be used up t o a t least 400' C. Figure 1 shows the thermostat. The bath liquid was contained in a sheet-iron pot surrounded by magnesia a t d, retained by a thin sheet-iron cylinder with a wooden bottom. The pot was set on magnesia bricks and fastened down by the rods, e, whose ends hooked over the edge of the pot. The brass stirrer, s, was made without soldered joints. The stirrer shaft was made of chrome steel and its bottom bearing of monel metal. The stirrer was clamped close t o the top of the pot a t c, and by the brace, b. The stirrer was operated by the motor, a, fastened t o the wooden baseboard. The temperature control was obtained by the mercury regulator, r , which Elvins and S a s h , Y n t u r e , 118, 154 (1926), F u e l , 6 , 263 (1926). S a s h , Chemisfry and Industry, 46, 876 (1926); J . Insl. Petroleum Tech., 13, 597 (1927). 7 Elvins, J . Soc. Chem. Ind., 46, 4731'-(19'27). Unfortunately, in the preliminary report from this laboratory, reference was not made t o this article because i t was not available to the writers until after the report was prepared and sent to the publisher, 8 Erdely and Nash, Ibid., 47, 219T (1928). 5
6
1342
INDUSTRIAL A N D ENGINEERING CHEMISTRY
c W Figure 1-Fused-Salt
Bath Thermostat
fitted into a bracket hooking over the edge of the pot at f. The capillary tubes from the regulator extended out of the bath far enough so that they remained cool. A modified telegraph relay (not shown in the figure) was operated by the mercury contact in the regulator and opened or closed the circuit through one of the resistance heaters, It. The current in the other resistance heater was adjusted so as to maintain the temperature of the bath just slightly below that desired. The heaters were not fastened but merely rested on the bottom of the pot. The thermostat as a whole could be raised up t o or lowered away from any fixed apparatus used therein, by means of the jack, 1. Three guides were made from standard pipe fittings with clamps as shown at i . This thermostat has been in practically continuous operation for many months without excessive corrosion having occurred. The stirrer was run only when necessary, because the wear on i t was considerable. The design of the thermostat was thus such that all parts could be readily taken out of the bath liquid. A detailed drawing of the resistance heaters is shown in Figure 2, which is self-explanatory. The cooling fins are necessary t o prevent possible “creeping” of the fused salt up t o the heating wires. The caps on the end of the seamless-steel enclosing case are screwed on against copper gaskets as shown. This construction permits convenient replacement of the heating element without destroying the protecting case. The creeping of the fused nitrates is not nearly so serious on iron surfaces as on copper, brass, or monel metal. The temperature of the thermostat was determined by means of the resistance thermometer, t , and a thermometer bridge. The maximum variation of t h e thermostat temperature during a n experiment was =t0.3”C. The average temperature was probably known to 0.1”C. SYNTHESIS APPAuTus-‘l’he apparatus used for carrying out the synthesis is shown in Figure 3. The apparatus to the right of e (save for the meters and the gas-holder, 5 ) was made entirely of glass. Water gas was made by steaming active charcoal in a small generator electrically heated t o about 950” C. The gas was passed over special bog iron ore t o remove hydrogen sulfide and was stored in a 7-cubic meter gas-holder. The gas as made contained about 1 per cent of carbon dioxide and a few tenths of one per cent of oxygen. This gas was passed over heated copper gauze in b t o remove oxygen, through lump sodium hydroxide in c to remove carbon dioxide, and over calcium chloride in d t o dry the gas further. The gas then passed through a carefully calibrated wet meter, e, in which the usual water was replaced by a fluid mineral oil (“Russian White Oil”) which had negligibly small vapor pressure. Final purification of the gas was effected by passing it through the trap, f, cooled in liquid air and packed with glass beads and glass wool. This removed all sulfur compounds and heavy gases. The catalyst was contained in the glass spiral, h. The catalyst tube was of small diameter in order to avoid overheating and a loop (not shown in the figure) was provided in order to preheat the incoming gas t o the temperature of the thermostat
Vol. 20, No. 12
bath which surrounds the catalyst tube. All heavy products were caught in the receiver, k, cooled in liquid air. The unused CO and HZand most of the CH, passed through the meter m, which was similar t o the meter e. A continuous sample of the gas emerging at n was obtained by allowing mercury t o run slowly from a gas pipet connected by a T t o the exit tube. Frequent meter readings were taken during an experiment in order to determine the rate of gas flow and the contraction in gas volume. After an experiment the condenser, k, contained the following products: all hydrocarbons above CH4 except a small amount of GHd which was found in the exit gas; occluded CH4, CO, and H2; C02; H20. Quantitative handling of these products was accomplished as follows: The condenser, i, was allowed to warm up t o about 0” C., the gaseous products passing first through a fractionating condenser, q, maintained at the temperature of carbon dioxide snow, which experience showed under the conditions t o retain substantially all hydrocarbons from propane and propylene up. The gas then passed through a weighed KOH solution (not shown in the figure) to absorb COZ and through a gas meter (containing water instead of oil and previously flushed out with NZ).The condenser and connecting tubes were then flushed out with N2 to carry over all remaining gases. The gas fraction containing the previously occluded CO, Hz, and CH4, C2H4, GHe, and Nz was collected in the small gasholder, s. The products in p were then distilled back into the condenser, i, which had again been cooled with liquid air. A small condenser with a calibrated tube at the bottom was now connected at j and immersed in liquid air. The liquid products were run over into it through the capillary, j . Finally, the condenser, i, was surrounded with a n electric heater and all remaining products flushed with Nz into the calibrated condenser attached at i. The products in the small calibrated condenser were again allowed to come t o about 0” C. and subjected to a second fractionation from o through g, the gas being added t o that in s and the condensate being returned to the small condenser attached at o. The gas meter was then flushed with N t o carry the gases into s. Analyses of incoming and exit gases and of the “condensate gas” from s were made on the modified Orsat apparatus.9 I n the 6rst series of experiWires insulated ments the volumes and weights of water and of liquid hydrocarbons were determined in the small calibrated condenser, the weight of hydrocarb o n s s o determined including the Silver-soidered joint weight of gas, and the volume of liquid hydrocarbons, including that of dissolved gaseous hydrocarbons. In the second series the products were subjected to another fractionation t o remove from the liquid hydrocarbons all products below pentane and amylene. The volume of the gas fraction was accurately determined and a n analysis of it was made by fractionation in a modified Shepherd-Porter train.10 I n all cases apparatus of appropriate size t o avoid loss due to waste space was used, handling of the products was done in a closed system, and precautions were taken to sweep out dead space in the apparatus with nitrogen so as not to lose any of the products. Finally, further examination of the liquid hydrocarbons was made by distillation analysis in certain cases and also by determination of the density and of the iodine num- Figure 2-Resistance Heater for Fused-Salt Bath ber according t o Wijs.” Preparation and Characteristics of Catalyst
In general, the catalysts which are effective contain as a major constituent a member of the iron group. There are apparently a number of materials which may be used as promoters or catalyst supports. It seems that the presence of copper should be desirable in a catalyst for this reaction, since it has a high s Fieldner, Jones, and Holbrook, Bur. Mines, Tech. Paper Sa0 (1925). “Frey and Yant, IND. ENG.Cxsar., 10, 492 (1927). 1 1 Lewkowitsch, “Chemical Technology and Analysis of Oils, Fats, and Waxes,” Vol. I, p . 308, Macmillan Co., New York, 1909.
December, 1928
INDUSTRIAL AND ENGINEERING CHEMISTRY
1343
Figure 3-Apparatus for Synthesis of Hydrocarbons from Water Gas
heat conductivity and yet does not induce methane formation. Also, it is said to assist in the reduction of other oxides, permitting reduction a t a lower temperature. I t would also seem desirable to have, in addition, a supporting material consisting of a non-reducible oxide. The different combinations which can be made of such materials are manifold. Up to the present, partly upon the basis of their preliminary experiments, the writers have therefore settled upon a catalyst that seems to represent a reasonable combination of desirable characteristics and a reasonable proportioning of the three constituents, and have made a study of the characteristics and functioning of this particular catalyst. Thus they have so far centered their attention perhaps more on the process and the conditions which affect this particular catalyst rather than on the alterations that can be made in the constituents of the catalyst and in their proportions. The writers feel that their catalyst, especially that used in the last experiment recorded in Table 11, represents an approach to the maximum activity which can a t present be expected of a catalyst for the practical operation of this process. It seems obvious that the mechanism of the reaction by which the heavier hydrocarbons are formed from water gas, must involve many steps and probably several secondary reactions. For example, it seems evident that unsaturated hydrocarbons, after their primary formation, undergo direct hydrogenation and also polymerization. In a reaction which probably involves so many steps, it is unlikely that equilibrium conditions wi!l be closely approached under practical operating conditions. Although it is possible that the heats of activation of some of the reactions may be rather small under certain conditions and thus that the reaction may be made to take place a t a lower temperature, there is certainly a limit to the conversion that can be expected upon one pass over the catalyst, on account of the reduction of the partial pressures of the reacting gases. This is especially true if the reactions are of higher order than the first. And, as will appear later, irrespective of the activity of a catalyst there is a temperature below which it is not feasible to operate, on account of clogging of the catalyst with the heavier products of the reaction. The writers have found that the activity of their catalyst depends to a predominant extent upon its method of preparation and reduction. They have also found that even a few cubic centimeters of unpurified water gas (with its very small content of sulfur), upon contact with an active catalyst, will reduce its activity enormously. Overheating in the presence of water gas will also markedly reduce the activity of an active catalyst. The catalysts which were used in the preliminary work,' although of suitable chemical composition, were not very active, for the following reasons: (1) Their reduction was carried out a t too high a temperature; (2) they were probably overheated: (3) the gas was not completely devoid of sulfur compounds. Since these catalysts were not very active, they were naturally rather insensitive. All the catalysts involved in this paper were made as follows: (1) 881 grams C o ( N 0 ~ ) ~ . 6 H ~150 0 , grams MnCl2.4H20, and 183 grams Cu(N0&.3H20 were dissolved in 3 liters of water and the solution filtered; (2) 220 grams NaOH dissolved in 500 cc. of water were added slowly with stirring to the above solution heated to about 85' C.; (3) the precipitate was washed by decantation until it began t o become colloidal: (4) it was then filtered on muslin, compressed into pellets about 8 mm. in length and 2 mm. in diameter, and dried slowly up to a final temperature of 200' C.; ( 5 ) the dried catalyst, freed from fines, was placed in the catalyst tube and reduced first a t 150' C. with hydrogen diluted with nine times its volume of nitrogen,
the temperature and concentration of hydrogen being gradually increased until finally pure hydrogen was used a t 300" to 325' C. It is probably advisable to use pure materials in the catalyst preparation or, a t any rate, to avoid the use of compounds containing sulfur. The precipitation from a hot solution and the thorough washing tend to produce a very finely divided material. A gross catalyst volume of 300 cc. was used in all experiments. Catalysts 1, 2, and 3 (in tables) were all rather active when first tested, but all were inadvertently overheated in the first test because their activity was underestimated. In each case, on the first test, reaction took place so rapidly that local overheating and excessive production of methane occurred. Since these catalysts all retained a considerable activity, they were used nevertheless. Because i t was desired to investigate the effect of temperature and of rate of gas flow using a catalyst of cbnstant activity, it was thought as well to use a catalyst of moderate activity, since such a one would be expected to be relatively insensitive and would, therefore, not be likely to exhibit such marked changes in activity as would a very active catalyst. Even so, it was found that the activity of the catalyst often changed and reproducibility of the results was not so readily attained as was the case in the previous work. Even when using the writers' thermostat bath of excellent heat capacity and heat conductivity and the catalyst tube of very small diameter, local overheating of the catalyst frequently occurred. One must be cautious, then, about inferring the temperature of the catalyst itself from that prevailing nearby. It is probable that in much of the previous work local overheating of the catalyst frequently occurred, leading to underestimation of the actual catalyst temperature. It was always noticed that the initial contraction in gas volume was greater than the subsequent contraction during a single experiment. For example, in test 22 the contraction ran as follows: first half cubic foot, 25 per cent; second cubic foot, 18 per cent; seventeenth cubic foot, 13 per cent; twenty-first cubic foot, 9 per cent. Upon sweeping out the catalyst with hydrogen, the contractions were as follows: first half cubic foot, 25 per cent; seventh cubic foot, 12 per cent; thirty-fourth cubic foot, 14 per cent. After sweeping out the catalyst with nitrogen the contractions were: first cubic foot, 12 per cent; tenth cubic foot, 7 per cent. Thus, besides the sweeping-out effect, hydrogen seems to have a specifically beneficial effect, due to its reducing action. It is worthy of note that in certain cases the activity of the catalyst (as measured by the contraction in gas volume) may be more or less permanently increased by treatment with hydrogen after the catalyst has been used. It seems likely then that, especially when using a gas rich in hydrogen, the activity of the catalyst may in certain cases improve with use. It was also observed that careful oxidation and reduction of a catalyst, which had been poisoned by sulfur, restored its activity to a considerable extent. The activity of a poisoned catalyst, however, never returned quite to its previous value. As to the life of an active catalyst under the conditions obtaining in these experiments, the 300 cc. of catalyst No. 3 had between 7 and 8 cubic meters of water gas passed over it without noticeable impairment. It seems likely that, with proper purification of the gas and with protection against overheating, a catalyst of this nature will last indefinitely. The writers attempted t o make satisfactory catalysts (1) by ignition of the nitrates upon diatomite brick, and (2) by mixing this supporting material with a sludge of the hydroxides. Although catalysts of moderate activity were obtained, espe-
INDUSTRIAL AND ENGINEERING CHEXISTRY
1344
T a b l e I-D
Hz Liters
CO
CH4
a f r o m t h e F i r s t Series of S y n t h e s i s E x p e r i m e n t s
UNCHANGED
GAS ENTERINGa
GAS Na
Liters Liters Liters
Vol. 20, No. 12
Hz
CO
Liters Liters
3.6 33.1 46.2 83.4 43.9 27.3 34.8 41.7 46.8 93.8 92.0 43.6 37.7 30.9 60.5 49.9 48.4 44.9
0.2 38.6 47.0 89.1 51.4 35.2 39.6
45.1 48.1 93.1 93.3 46.7 44.2 38.7 61.1 50.9 48.3 46.3
GASEOUS HYDROGAS CONVERTED CARBONS FORMED HI
CO
CHab CzHa CzHa
I
Liters ~ i t e r s Liters Liters Liters 58.6 30.3 15,s 42.0 28.7 36.2 28.4 22.2
16.3 16.2 24.2 21.4 26.9 33.0 16.0 14.0 14.4 18.3
I
YIELD OF HIGHER HYDROCARBOSS
C
82
'2
-
Wt.
Per Per Vol. liter Hz liter CC used up used ur
Gram Lrters :rams Cc. Not det ermine d 24.16 5.78 0.109 3.89 3.36 3.67 0.185 1.20 3.00 3.25 7.77 10.59 0.181 4 . 7 4 6.57 0.162 3.66 5.87 6.85 8.97 0.192 3.76 5 . 4 1 0.131 5.24 4.44 0.144 3.82 3.27 3.38 0.153 1.54 2.56 0.89 1.95 2.68 0.116 3.50 0.104 0.82 2.59 0.91 1.87 2.81 0.086 1.57 2.89 4.08 0.106 5.48 0.128 4.11 4.28 0.79 1 . 7 2 2.10 0.104 0.50 1.65 2.85 0.114 2.50 0.135 0.58 2 . 0 0 3.28 0.139 0.84 2 . 6 2 I
Gram 0.168 0.229 0.261 0.225 0.253 0.191 0.232 0.217 0.180 0.216 0.152 0.202 0.223 0.202 0.226 0.224 0.234
WATER VAPOR ?ORYED
Ltters 6.93 14.90 8.33 18.76 12.42 13.27 11.16 9.61 8.49 11.09 9.43 9.30 11.47 12.68 8.17 7.64 8.01 8.31
a Percentage composition of entering gas may be calculated from these values of total volumes of reactants used. b These CH4 volumes represent excess of CHI in products over t h a t from entering gas. o These COz values are subject t o slight error in some cases, due t o escape of COa through ROH absorber and its subsequent dissolving in water in gas-
holder.
cially in the second way, and perhaps could be improved, they were more successful in using their standard method, even though it required more materials and a longer time to prepare them. Catalysts of this nature oxidize rapidly upon exposure t o air at room temperature. It is evident that oxidation of the catalysts with air may occur a t temperatures far below those necessary for subsequent reduction with hydrogen. It is believed desirable, therefore, t o remove oxygen completely from the gas used in the synthesis of hydrocarbons.
the examination of the products in the Shepherd-Porter apparatus. Furthermore, within the experimental error, the total oxygen of the entering gas appeared in CO2 and H20. The amounts of oxygenated products formed must have been comparatively small. Although the fact is not indicated in the tables, as mentioned previously, the initial contraction in gas volume in B single experiment was always largest. I n very long experiResults of Synthesis Experiments ments the contraction usually settled down to a more or less constant value after considerable gas had passed over the The experimental data are presented in Tables I, 11, and catalyst. After each experiment the catalyst was flushed 111, which are, for the most part, self-explanatory. All gas out with hydrogen, the temperature being gradually increased volumes given in the tables are corrected to 0" C., 760 mm. to 250-300" C. This brought the activity of the catalyst I n Table I the weights of liquid hydrocarbons produced in- substantially to its previous condition. Also, a t the higher clude some hydrocarbon vapor, and the volumes include the temperatures the percentage decrease in activity of the cataincreased liquid volume due to dissolved gaseous hydro- lyst during a single experiment was not nearly so great as carbons. a t the lower temperatures. This might be due to the greater I n Table I1 more complete data are given on the nature and ease with which the products are distilled out of the catalyst properties of the hydrocarbons produced, since in these tests at the higher temperatures. the gas fractions of the heavier hydrocarbons were analyzed Although it would be desirable to make a complete mawith the Shepherd-Porter apparatus; sharp fractionations terials balance between reactants and products, there are were made in order to include only the hydrocarbons from certain practical difficulties in the way of this. First, it is pentane and amylene up in the liquid products; iodine num- very difficult to be sure of gas volumes, when measured by bers were obtained; the specific gravity of the liquid fraction the wet meter, to better than about 1 per cent. Further, was determined; and, in the case of the two long experiments even with very careful gas analyses, i t is difficult to be certain (tests 23 and 24), distillation and examination of the liquid of the amount of the constituent to better than 1or 2 per cent products were made as shown in Table 111. in the case of certain gas samples. For example, with a gas Table IV shows, for the second series of tests, the yields of containing CO and Hz and a small amount of CH4 the best the various hydrocarbons per liter of Hz or CO which has standard method of analysis in certain cases will not deterbeen used up in the pro-cess. Table V shows-the percentage mine the amount of COand Hzto better than about 1per cent composition of the total hydrocarbon products in order to of the amount of the constituent. Frequently the errors w ill indicate better the differences in the nature of the products be as much as 3 per cent of the amount of the constituent. which are obtained under different conditions. The volumes Although these errors in themselves are not serious, when one the heavier hydrocarbons would have as gas were calculated has, say, 10 per cent of the original CO and H2 going to form from an estimated average molecular weight. Table VI hydrocarbons, an error of 1 per cent in the total CO and gives the yields of total hydrocarbons produced in the differ- Hz used introduces 10 per cent error into the absolute ent experiments per liter of reactants converted. Finally, amount of carbon and hydrogen going to hydrocarbons. Of in Figure 4 are shown the theoretical yields of various paraffin course, without knowing the carbon : hydrogen ratio in the and olefin hydrocarbons when the oxygen goes either to HzO liquid hydrocarbons formed, an accurate materials balance of carbon and hydrogen is not possible. Also, since in certain or to COZ. No direct determination was made of the amount of oxy- cases, as noted in Tables I and 11, the COn values are somegenated products formed. These, however, owing to their what uncertain due to the escape of some of the COZthrough solubility in the relatively large quantity of water which was the KOH absorber, and its subsequent loss through its disalways present, could not have been included with the hydro- solving in the water in the gas-holder, the materials balance is carbon products. Furthermore, repeated extractions of these subject to error. The percentages of constituents in the total products with water failed to remove an appreciable amount hydrocarbon products (Table V) are in general accurate, of material. No oxygenated products were ever detected in since in this case the analyses were made on the products
December, 1928
INDUSTRIAL AND ENGINEERING CHEMISTRY
themselves and do not depend upon analyses of the total of the reaction was that reactants used. Of course, in certain cases there was in which the oxygen probably a small and unavoidable loss of products. Further- went to HzO r a t h e r more, in certain cases the sample of the unused gas may not than to COZ. Let us examine a few be an entirely average sample. I n considering the yields per unit volume of gas used up, these uncertainties must of the results upon this basis, neglecting the be remembered. In considering the yields, let us first examine the theoretical GO2 formation for the possibilities as set forth in Figure 4. Since it appears that sake of simplicity and only paraffins and olefins are formed in this process,12 taking the data on the no other hydrocarbons need be considered. The case of the total weights of hydroolefins is simpler. The yield in grams of any olefin per liter carbons per liter of reof GO reacting when HzO is formed is the same as that per liter actants converted, from of Hz reacting when GO2 is formed. These yields are inde- Table VI. The conpendent of the molecular weight of the olefin and the value is clusions so deduced 0.625 gram per liter. The same is true for olefin yields per may be compared with liter of Hz reacting when HzO is formed and per liter of GO the data in Table V. reacting when COZ is formed. I n this case, however, the Of course, these deducyield is 0.31 gram per liter. Thus, if we considered a reac- tions cannot be made tion in which equal volumes of water vapor and COZ were too pointedly nor from formed and assumed a water gas containing 50 per cent HZand all the test data, since, 50 per cent CO, the yield of any olefin would be 0.208 gram per as mentioned before, liter of water gas. If the olefin were C7HI4we would have 2.2 t h e a c c u r a c y w i t h gallons of liquid per 1000 cu. ft. of water gas. In the case of which these yields can the paraffins the yield, in grams of paraffin per liter of reactant, be determined i s n o t depends upon the particular paraffin considered. The yield high. Two or three of of paraffin per liter of Hz when either HzO or COZ is formed the values in column 6 increases with increasing molecular weight of paraffin. The of Table VI are obviyield of paraffin per liter of CO when either HzO or COZ is ously too low. I n genformed decreases with increasing molecular weight. If C ~ H M eral, however, they are were formed from a water gas containing 47.7 per cent CO as consistent as could be e x p e c t e d and are comparable one w i t h another. Of course, unless t h e reaction which leads to GOz formation is considered, the yields per liter of CO will appear especially low. For example, if the volume of COz formed is 10 per cent of the volume of water vapor f o r m e d , the theoretical yields of CH, are changed as follows: From0.24 to0.25 gram per liter of Hz; from 0.71 to 0.61 gram per liter of CO. Considering tests 21 and 22, which were run with different rates of gas flow but at the same 021 1 I I I 1 CHI cs ClO CI, Chl temperature, the yields ATOHS OF CARBON PER YOLECLLE OF H I DROCARBO\ per liter of Hz and also Figure 4-Theoretical Yields of Various Olefin of CO are higher in No. and Paraffin Hydrocarbons i n Grams per Liter of Reactant 21. Referring to Figure 4, the higher yield and 52.3 per cent Hz and if equal volumes of water vapor and per liter of Hz can mean GO2 were formed, we would obtain 0.20 gram C1H16 per liter e i t h e r that relatively of water gas. This would likewise be about 2.2 gallons of more olefins a r e proliquid per 1000 cubic feet of water gas. Thus, the quantity duced a t the slower rate of yield obtained in an experiment, based on the volume of or that relatively higher reactants converted, should, other things being equal, give paraffins are produced. some indication of the nature of the products formed and the Data on the unsatureaction by which they were formed. I n these experiments, r a t e s show t h a t t h e the analyses of the products show that by far the greater part former conclusion is not 1 2 Fischer and Tropsch. Brsnnslof--Chem., 9, 21 (1928). justified, so the latter
1345
!J 0 0 0
p 4
!J n 0
,x n 0
cot FORMED5
INDUSTRIAL AND ENGINEERING CHEMISTRY
1346
T a b l e 111-Distillation
Vol. 20,
12
30.
Analyses of t h e L i q u i d H y d r o c a r b o n s _ _ _ _ _ _ ~
TEST33, TEMPERATURE 240° C. Fraction Original samgle 25O t o 1 0 1 . 5 C. 101.5°to 132.4' C. 1 3 2 . 4 O t o 184.3" C. Residue Loss
TEST24, TEMPERATURE 260' C.
Wt., grams
Per cent of total
Sp. gr. (20' C.)
Iodine number
11.82 4.88 2.35 2.86 0.68
100 0 41.3 19.9 24.2 5.8 8.8
0.6953 0.6601 0 7125 0.7535
90 138 70 30
. ...
Wt., grams
Fraction
24.4 11.87 2.37 6.36 1.95
Original sample 2.50 t o 101.50 c. 1 0 1 . 5 ' t o 131.6' C. 131:6'to 1 8 4 . 3 ' C. Residue
...
Percent of total
Sp. gr. (20' C . )
Iodine number
100.0 48.6 9.7 26.1 8.0
0.6974 0,6632 0.7190 0.7565
116 163 103 51
....
7.6
Loss
However, data on tests 24 and 25 in Tables I1 and V show that a t the lower temperature the percentage of CH, in the hydrocarbon products is about the same although the ratio H,O: CO, is very much larger a t the lower temperature. In general, the amount of C02 does not correspond to the amount of CHI formed. Regarding the percentage of CH, in the hydrocarbon products, it is usually true that with a given catalyst, other things being equal, there is proportionately more CH, formed at the higher temperatures. However, comparisons between tests 23 and 24 and between tests 24 and 25 in Table V show that other considerations are involved. With a more active catalyst about as large a proportion of CH, may be formed a t a lower temperature. I n fact, it seems reasonable that a more active catalyst. might produce more CH4 as well as more higher hydrocarbons. Also, when a large amount of reaction is taking place with its resultant reduction in partial pressures of reactants, the rate of formation of one hydrocarbon may be more influenced than that of another. I n this connection it is well to remember that the order of the reaction to form a hydrocarbon, on a catalyst especially, is not necessarily higher the higher the hydrocarbon formed. It is evident from Table I1 that, with the same catalyst, relatively more unsaturates are formed a t higher rates and a t higher temperatures. The distillation analyses in Table 111, although performed on rather a small amount of product, were done very carefully and do, the writers believe, have a certain significance. Although it would have been desirable to have made more cuts in the fractionation they wished to get enough of each fraction to permit a determination of the density and iodine number. It is clear from these distillations that the proportion of residue of very heavy hydrocarbons is greater in the product from the experiment a t the higher temperature. It appears that relatively more heavier products may be formed
explanation may be accepted. Again, from Figure 4 we see that a higher yield per liter of CO can mean either that lower paraffins are formed or that relatively more paraffins than olefins are formed. The second conclusion is, of course, the correct one. From Table V we see that the percentage of products from pentane u p is 35 per cent a t the slower rate and 27 per cent a t the faster rate and from Table I1 relatively more saturated products are formed a t the slower rate. Thus, these deductions are verified. I n comparing, in the same way, tests 23 and 24, the yields per liter of CO are not significantly different. The yields per liter of H2 perhaps are. This fact can mean that there are either relatively more olefins or relatively higher paraffins formed in test 24. Other data indicate a combination of both. When Hp0 is formed in place of C 0 2 (as occurs to a predominant extent in all the tests), the yield of any hydrocarbon per liter of CO in a single experiment is always greater than the yield per liter of HB. This fact is evident in all the data. Other comparisons on this basis might be made but, owing to experimental uncertainties, the conclusions might be doubtful. The foregoing examples are given by way of illustration. A comparison of tests 19 and 23 shows that the hydrogenating properties of the catalyst decrease somewhat with use. Thus the iodine number of the total products from the long experiment is somewhat greater than the iodine number of the products from the shorter experiment. It is possible that decrease in the hydrogenating activity is accompanied by a general decrease in the activity of the catalyst corresponding to the decrease in contraction of gas volume as an experiment proceeds. A comparison between tests 1 and 2 in Table I s h o w that the ratio H20:COz decreases with increasing temperature. I n these two tests this fact might be attributed to the increased formation of CH4 a t the higher temperature. Comparison of tests 19 and 20 in Table I1 might also indicate this.
T a b l e IV-Relative
ETHYLENE
METHANE
?$-TEMP. ; : :F
TEST
3 3 3 3 3 3 4
18 20 21 22 23a 24 25
240.0 280.0 240.0 240.0 240.0 260.0 203.5
1.30 1.24 0.66 1.79 1.28 1.28 1.24
Per ligzr
Total
Per Per liter liter CO Hz CO used up used up used up
2.61 3.56 2.57 1.83 12.12 16.20 1.39
0,0796 0 1102 0.0924 0.0753 0.0687 0.0537 0.0668
0.1411 0.2106 0.1713 0.1476 0,1331 0 0940 0 1094
0,0509 0.0724 0.0600 0,0499 0.0453 0.0342 0.0415
0.70 0.48 0.45 0.94 3.20 10.89 1.09
0.0213 0.0149 0.0162 0,0387 0.0182 0.0361 0.0524
0.0378 0,0284 0.0300 0.0758 0.0351 0.0632 0.0858
Yields of Hydro-
PROPYLENE
ETHANE
Per Per Per liter liter Hz CO HzIYCO used up used up used up
+
...
0.0136 0,0098 0.0105 0.0256
0 0120 0.0230 0.0325
Total
Per Per Per liter ; :1 ,li;rc0 Hz used up used up used up
1.65 1.47 1.33 0.60 5.66 13.78 1.62
0.0503 0.0455 0.0478 0.0247 0.0321 0,0457 0.0779
Total
Per liter H1 used up
0,0892 0.0870 0.0887 0.0484 0.0621 0.0799 0,1276
See note on this experiment in Table 11.
Composition
T a b l e V-Percentage
"z&- 2%
TEST
TEXP.
ETHYLENE
METHANE
Volume
C. L./min.l Lifers
5%
I
Weight
1 Grams
See note on this experiment in Table 11.
Volume
5%
1
ETHANE
Weight
% 0.56 0.38 0.36 0.75 2.56 8.71 0.87
8.11 5.28 6.10 17.38 8.81 16.89 18.56
0.70 7.38 5,98 0.48 5,70 0.45 0.94 17.54 7.98 3.20 10.89 14.16 1.09 16.03
Volume
Liters
70
1.23 1.10 0.99 0.45 4.22 10.28 1.21
17.82 15 30 16.78 10.43 14.52 19.93 25.81
1
I
Weight
7% Grams 1 . 6 5 17.41 1.47 18.31 1 . 3 3 16.84 0.60 ~1.19 5.66 14.11 1 3 . 7 8 17.91 1 . 6 2 23.82
PROPYLENE
Volume
Liters 70 0.233 0 . 0 3 4 03 . 43 7 0.044 0 . 7 5 0.085 1 . 9 7 0.615 2.12 1.454 2 . 8 2 0.070 1 . 4 9
I
Weight
Grams
70
0 .0 46 4 0.08 0.16 1.15 2.73 0.13
04 . 76 46 1.01 2.98 2.87 3,55 1.91
INDUSTRIAL A N D EXGINEERING CHEMISTRY
December, 1928
a t a higher temperature, in the case where the reactions are always far from equilibrium, when other things are equal. The density of every fraction from the product obtained a t the higher temperature is higher than that of the corresponding fraction of the lower temperature product. (It is to be noted that the density of an unsaturated hydrocarbon is in general greater than that of the saturated hydrocarbon with the same number of carbon atoms per molecule.) Not only do the fractions have higher densities, but they have even relatively higher iodine numbers. If we assume that the very heavy products are formed through condensation of lower unsaturated products, we can explain how relatively more heavier products are formed a t the higher temperatures. Since, for example, the condensation of 2C2H4 to C4Hgis accompanied by only a very small evolution of heat (about 1200 calories), the equilibrium constant for this reaction, and thus the ratio of the specific rate of polymerization to that of dissociation of the polymerization product would change only about 5 per cent between 240" and 260" C. That is, the tendency for dissociation of the polymerization product is little greater a t 260' than a t 240" C. The rate of the reactions as a whole which are involved in the synthesis of hydrocarbons from water gas would seem to increase about 60 per cent for this temperature change. Since the partial pressure of unsaturates from primary reaction is probably much larger a t the higher temperatures and the rate of dissociatioq of the polymerized products is but little greater, relatively more polymerization of unsaturates might occur a t the higher temperature and consequently relatively more heavier products could be formed. All indications seem to point t o the formation of unsaturates (probably of low molecular weight) as the primary reaction. Secondary hydrogenation results in the formation of paraffins, and polymerization results in the appearance of the very heavy hydrocarbons, which may in turn be hydrogenated. Such hydrogenations and polymerizations in general are thermodynamically possible a t the temperatures involved. It is suggested that the primary reaction is the formation on the catalyst surface of CH2 groups through condensation of which (or of the polymerization products of which) all of the higher hydrocarbons are formed. I n later work the writers hope to investigate various questions such as are suggested herein regarding the mechanism of the reactions involved in this process. Of course, if the materials balance were perfect, the yields
1347
of the hydrocarbon products would be the theoretical as shown in Figure 4,except for any small amount of oxygenated products which may be formed. As to the yields of all hydrocarbons above methane, it is seen from Tables V and VI that these vary from 92 to 156 grams per cubic meter of H2 CO used up. These figures may be compared with Fischer's stated 100 grams per cubic meter of water gas.13 What is of more interest experimentally than the yields of all hydrocarbon products per unit volume of reactants (Hpand CO) used up in the process is the composition of the products obtainable, as shown in Table V. It is seen from this table that in every case an appreciable portion of the total hydrocarbon products is methane. This varies from 20 weight per cent up. It is evident, then, that this process could not in general be operated economically-for example, for the production of liquid fuel-unless the heat units represented by the methane could be utilized or unless the formation of methane could be markedly reduced. The nearest approach to practical utilization of this process a t present would seem to be in the gas industry, where use could be made of the methane and the lighter hydrocarbons for enrichment purposes.
+
Table VI-Comparative
Yields of Total Hydrocarbons Produced
TOTAL I~YDROCARBONS CATA-
GAS
TEST LYST TEMP. FLOW
Per liter Hz used UP (6)
Weight
(5) C. 240.0 250.0 240.0 240.0 240.0 260.0 203.6
3
19 20 21 22 23a 24 25
3
3 3 3
3 4
Per liter
CO used up (7)
Per liter HZ CO used up (8)
+
L./min.
Grams
Gram
Gram
Gram
1.30 1.24 0.66 1.79 1.28 1.28 1.24
9.48 8.03 7.90 5.36 40.10 76.92 6.80
0.2813 0.2440 0.2801 0.21276 0.2201 0.2497 0.3178
0.4912 0.4615 0,5129 0.4061b 0.4154 0.4311 0.5113
0.1789 0.1696 0,1812 0.1396 0.1439 0.15Sl 0.1960
a See note on this experiment in Table 11. b The reason for these low values is not known. cussion of them.
See the text for dis-
There is, of course, a loss of heat units in this process. In general, the heating value of the hydrocarbon products formed is from 76 to 80 per cent of that of the reactants (CO and H2) used in their formation. I n the practical operation of this process on a large scale, the catalyst chamber would have to be designed to carry 13
Fischer, Proc. International Conference on Bituminous Coal, p. 245.
carbons in the Various Tests PROPYLENE
I
Gram 0,0238 0.0036 0.0053 0.0128 0.0126 0.0158 0,0102
Gram 0.0086 0 0012 0.0019 0 0044 0.0043 0.0058 0.0039
I
PROPANE
Per Pel litpr liter CO H 2 + C O used up used up
Grams Gram 0 . 8 6 0.0262
0.436 0.165 0.197 0.103 1.131 1.380 0.058
6.32 2.30 3.34 2.39 3.89 2.68 1.24
Per Per liter liter CO Hr CC used up used up used up
'E
0.32 0.39 0.20 2.22 2.71 0.11
0.0009 0.0140 0.0082 0.0126 0.0090 0.0053
Gram
Gram
Grams
Gram
0.0465 0.018s 0.0260 0.0161 0.0244 0.0157 0.0087
0.0168 0.0065 0.0091 0.0056 0,0083 0.0067 0.0033
0.18 0.10 O,l5 0.09 1.16 3.04 0.09
0.00% 0.0031 0.0054 0.0037 0.0066 0.0010 0.0043
PROPANE Volume
Per
+
1
Gram
0.0097 0.0035 0,0059 0.0020 0.0100 0.0035 0.0073 0.0026 0,0127 0,0043 0.0176 0.0064 0.0071 0.0027
Total
9.07 3.99 4.94 3.73 5.54 3.52 1.62
Volume
0.072 0.039 0.058 0,034 0.466 1.214 0.037
1.04 0.54 1.00 0.79 1.60 2.35 0.79
1
UD
Grams Gram 0 50 0 0152 0.18 0 17 0 07 0 83 1 68
0 05
0 0 0 0 0 0
1.90 1.25 1.90 1.68 2.89 3.95 1.32
Volume
1
Gram
Gram
0.0270 0.0097 0.0107 0.0037 0.0113 0.0040 0.0056 0.0019 0,0091 0.0031 0.0097 0.0036 0.0039 0.0015
0056 0061 0029 0047 0056 0024
0,191 0.068 0.066 0.029 0.319 0.647 0.020
2.77 0.95 1.12 0.67 1.10 1.25 0.43
1
PENTANE A N D HIGHER
Per liter liter Per CO H z + C O used UD used UD 1
BUTAXE
Weight
0.18 0.10 0.15 0.09 1.16 3.04 0.09
Per 1Er used
BUTYLENE
Weight
0.86 0.32 0.39 0.20 2.22 2.71 0.11
+
Gram
1
BUTANE
BUTYLENE
Per Per Per liter liter liter Hz CO €11 CO used up used up used up
Per Per Per liter liter liter Hz CO H I + C O used U D used UP used UD
I Grams 2 54 1.86 2.76 1.47 13.76 25 89 2.32
Gram
Gram
Gram
0.0774 0.0576 0.0993 0.0605 0.0780 0,0859 0.1115
0.1373 0,1101 0.1840 0.1186 0.1511 0.1502 0.1827
0.0495 0.0378 0.0645 0.0401 0.0615 0.0546 0.0693
PEKTANE A N D HIGHER Weight
0.50 0.18 0.17 0.07 0.83 1.68 0.05
5.27 2.24 2.15 1.31 2.07 2.18 0.74
I
Volume
0.531 0.424 0,593 0.305 2.823 5.244 0,473
7.69 5.90 10.05 7.07 9.71 10 17 10.09
1
Weight
2.54 1.86 2.76 1.47 13.76 25.89 2.32
26.79 23.16 34.94 27.43 34.31 33.66 34.12
INDUSTRIAL A N D ENGINEERING CHEMISTRY
1348
away efficiently the heat of the reaction and maintain rather close temperature control throughout the relatively large volume of catalyst which would be necessary. This would present some difficulty, but it probably could be accomplished. The reaction heat could be used to preheat the reactant gases and the process would be self’-sustaining. The sulfur compounds in the gas used would have to be completely removed in order to insure long life for the catalyst.
Vol. 20, No. 12
Acknowledgment
The writers are indebted in many ways for such information as has been published by Fischer and Tropsch, by Elvins, Nash, and Erdely; and also for the preliminary work from this laboratory in which J. D. Davis participated. They are also indebted to many of the chemists of this laboratory and especially to A. C. Fieldner, under whose direction this work was done.
Some Economic Factors in Chemical Price Making’ Williams Haynes CHEMICAL M A R K E T S , 25
SPRUCE ST., N E W Y O R E ,
RICES tend to approximate the cost of production. If prices rise far above the cost of making any kind of goods, profits become abnormally large; and not only will the present manufacturers increase their output, but others will also be tempted to embark on the making of these same goods. If prices drop below the cost of production, manufacturers lose money. First, they curtail their operations, and eventually they forsake the enterprise or are forced into bankruptcy. In the former case increased production and keener competition will bring abnormally high prices back to the normal level, which is the cost of production plus sufficient profit to keep enough manufacturers in the business of supplying the normal demand. In the latter instance, reduced production will bring supply below demand and this scarcity will force prices back to the normal level. In this way the control exercised by price keeps supply and demand in balance, and price in turn is determined by the relative strength of supply and demand. In a general way everyone recognizes these broad principles. Noriarity points out:
P
For anything that he really wants the average buyer is willing to pay whatever he believes i t costs to produce it. I n part this willingness springs from his sense of fairness and in part from his commonsense knowledge that the market price of producible goods cannot drop below the cost of production without reducing the future supply. On the other hand, the buyer resents being compelled to pay for anything a price which he feels gives either t o the maniifacturer or the middleman more than a fair profit. Indeed, so strongly does the average buyer feel that he is entitled to as low a price as free competition would bring about, that even when he recognizes an article is really worth more t o him than the market price which he regards as unfairly high, he will buy less of such an article if he can possibly get along without it. On the other hand, even when he feels that the price of a n article is unduly high he will make little protest and will not tend t o boycott the industry, if he can be convinced that the market price is not higher than the costs of production, including a fair profit.
As we found wide variations in the costs of producing the identical chemical in different plants, so there are variations in demand. Just as differences in cost enter into competition and affect profits, these differences in demand have great bearing on price and price policies. Use a n d D e m a n d
The demand for soda ash from a glass factory and one from a laundry are different in both degree and intensity. Kot only does the glass factory buy in carload lots, but also soda ash is essential for its operations. The laundry buys in kegs, and can, if necessary, dispense with the material entirely. The glass factory must have soda ash or shut down. The I
Received October 6, 1928
N. Y.
laundry can substitute trisodium phosphate, bicarbonate of soda, borax, half’ a dozen different modified sodas, or any one of a hundred proprietary cleansing compounds. The demand of the manufacturer of patent leather for collodion is different from the demand of the photoengraver or lithographer for the same material, and each differs from the demands of the makers of surgical dressings and of photographic films. The price that any of them will pay is influenced not a little by the use to which he puts the chemical and also by the price which he will eventually receive for the goods into whose manufacture it has entered. Formaldehyde is an essential in the manufacture of embalming fluid and in the production of certain synthetic plastics. The undertaker uses comparatively a small amount and its cost is but a tiny fraction of his charges. If its price rose to five, even to ten dollars a pound, but few of his customers would object. The manufacturer of the plastic, however, consumes vast quantities, and the product he manufactures comes into direct competition with other materials used largely in further manufacturing operations. To them, therefore, a difference of from 10 to 15 cents would mean a necessary increase in cost, which would shut them out from effective competition, for example, with hard rubber in the great electrical field. Finally, within a single industry there are differences in the demand among individual consumers. S o t only are there close buyers and careless buyers-differences which are purely physiological-but there are also differences in financial strength, in consuming ability, in manufacturing or marketing efficiency, all of which actually create real differences in the price that two firms using the same chemical for the identical purpose are able and willing to pay. These disparities of demand exist everywhere, in varying degrees, for all goods in every market. Effective Demand
Since demand is neither uniform nor constant, it must of necessity exercise a fluctuating influence upon supply. At what point, then, does this influence touch prices? Obviously, only what the economist calls “effective demand” need be considered. The woman who wishes for a diamond necklace without the means of paying for it exerts no more influence upon the price than does the manufacturer of drills who has substituted an exceptionally hard alloy of steel for a diamond tip. In like manner, a chemical substitute for rubber which can only be produced in the laboratory a t a price two or three times as great as that of the natural product will have no appreciable effect upon the rubber industry. On the other hand, the demand of a buyer who can afford to purchase with easy indifference to price, although it is certainly effective demand, does not have a determining influence upon
