INDUSTRIAL AND ENGINEERING CHEMISTRY
442
VOl. 19, No. 4
Manufacture of Amyl Acetate from Natural Gasoline'3z By Geo. T. Koch and Geo. A. Burrell 501 COLUMBIA B A N KBLDG.,PITTSBURGH, PA.
ASOLINE obtained from natural gas contains a considerable amount of the pentane hydrocarbons. These may be separated from the natural gasoline in suitable rectification towers and be used for the synthesis of amyl acetate. An outline of the research on this problem, including the principal difficulties encountered and how they were overcome, and a few cost figures are given herein. The process for the synthesis of amyl acetate from pentane may be briefly outlined as follows:
G
(1) Fractionation of pentane from natural gasoline (no reactions). ( 2 ) Treatment of pentane with chlorine to obtain chloropentane (amyl chloride) and hydrochloric acid, according to the reaction, CbHiz Clp CsHiiCl HCl (3) Esterification of amyl chloride to amyl acetate with sodium acetate, according to the reaction, CsHllCl Na(C2H302) +C5Hll(C2H302) NaCl
+ *
+
+
+
Besides these three major processes there are a number of minor ones, such as neutralization, fractionation, and rectification. I n describing the process in this paper all temperatures, pressures, or gravities mentioned are the ones which, up to the present time, have given the best results. Further operation and research will no doubt shorn instances where these values should be changed, resulting in greater efficiencier and economies. Fractionation of Gasoline for Recovery of Pentane
A standard copper-lined, steam-jacketed, continuous rectifying still is used. The fraction which distils over between 25' and 40" C. is the one most suitable for chlorination. This is essentially pentane, with some butane and hexane. The specific gravity of this fraction averages 0.625 a t 15.5" C. The recoveries vary according to the gravity of the gasoline being fractionated, being about 50 per cent pentane with a gasoline having an initial gravity of 84 O Be. Chlorination A number of previous investigators, in attempting to treat hydrocarbons with chlorine, carried out this reaction in the vapor phase, with varying results. The writers' first experiments were also in the vapor phase, but it was soon found that this method was difficult to control, the results were uncertain, and large amounts of di- and trichlor derivatives were formed. Furthermore, it was dangerous, for if the concentration of chlorine became too high, the reaction, being exothermic, proceeded so rapidly and violently that an explosion ensued, resulting in cracking the hydrocarbon vapors and the deposition of free carbon. Vapor-phase chlorination was therefore abandoned and attention turned to liquid-phase chlorination. APPARhTUS--,kfter considerable experimentation a method and apparatus (Figure 1) were devised by which chlorination could be carried on a t any desired rate and to any extent u p to a certain limit without danger of explosion or formation 1 Received December 8, 1926 2 Work was begun on the problem a t t h e laboratories of T h e Ohio Fuel Supply Co , Homer, Ohio, b y G. A. Burrell. T h e work was done for and the patents are t h e property of T h e Ohio Fuel Supply Company.
of the di- or trichlor d e r i ~ a t i v e s . ~The apparatus consists of a lead-free glass tube, fitted a t the ends with reducers and screens. Inside the large glass tube is a smaller tube, also of lead-free glass, extending approximately one-half of the vertical length of the large tube and supported a slight distance off the bottom screen. h small nozzle projects through the bottom screen and is directed into the end of the small tube. The lower end of the smaller tube is spread out in a funnel shape. Activated carbon, silica gel, or similar porous substances having large gas-absorption properties are used in connection with this apparatus as catalyst or chlorine carriers. Activated carbon of 12- to 15-minute chloropicrin test gives the best results. (Table I) The catalyst is placed on the bottom screen in the large tube to the depth of about 3 inches. Table I-Comparative
Chlorinations
DURATION
CATALYST USED
OF
CHLORO- CONVERSION PBNTANB
TO
AMYL
CHLORINATION RECOVERED CHLORIDE Minutes Kone 50-minute carbon (coconut shell) 15-minute carbon (Batchite) 12-minute carbon (Batchite)
45 45 45 45
Per cent 53 58
43 4i
Per cent 4.3 8.3 16.6 19.2
h'ote-These represent laboratory tests. In actual plant practice, using the 12-minute carbon, the average chloropentane recovered in over 3000 chlorinations was 78 per cent, and t h e average amyl chloride conversion 19 per cent.
OPERATIoPi-The pentane to be treated is run into the large tube until it is about three-fourths full. Chlorine gas is then admitted into the container through the small nozzle which is placed concentrically with respect to the funnelshaped mouth of the smaller tube or percolator. The rate of flow of chlorine gas is controlled from a master control panel similar to the chlorine apparatus used in municipal water plants. The chlorine gas emerging from the nozzle passes through the catalyzing material and up through the percolator tube, carrying a portion of the catalyzing material with it. While flowing up through the percolator, the catalyzing material and chlorine are in intimate contact in the presence of a small quantity of the liquid. Large amounts of the chlorine are absorbed by the catalyst. Upon spouting from the top of the percolator, the catalyst enters the reaction zone, where it comes in contact with a large quantity of pentane. The chlorine is dropped or displaced from the carbon a t this point and enters into reaction with the pentane. The reaction zone is exposed to actinic light emanating from a battery of mercury vapor lamps suitably placed. The particles of carbon, denuded of their chlorine, fall back to the bottom of the large tube in the space between it and the percolator, are again picked up by the chlorine jet, forced through the percolator, and then used over and over. The products of the reaction are hydrogen chloride and the chlorinated derivatives of the hydrocarbon being treated. Any vapors given off during the course of reaction pass from the reaction zone to a refrigerated condenser and are refluxed back into the tube. The hydrochloric acid vapors pass through the condensers into a washer, where they are absorbed t o form a weak solution of hydrochloric acid. I n order to keep this formation of di- and trichloride derivatives a t a minimum, chlorination must be stopped when This apparatus is covered under U. S. Patents 1,380,067 (May 31, 1921) and 1,432,761 (May 4 , 1920).
INDUSTRIAL A N D ENGINEERING CHEMISTRY
April, 1927
the chlorinated derivatives are about 20 t o 25 per cent of the total volume of hydrocarbons being treated. Using the apparatus described above, the reaction can be carried to this point in about an hour to an hour and a quarter. I n actual plant practice, recoveries of chloropentane were 78 per cent, with an average conversion to amyl chloride of about 19 per cent. Treatment of Chlorohydrocarbons and Recovery of Amyl Chloride
The chlorinated hydrocarbons coming from the chlorinators are very acid and must be washed and neutralized before being fractionated to recover the amyl chloride. This is done in a covered tank equipped with agitators. A 10 to 20 per cent caustic solution is agitated with the chlorohydrocarbons for about 20 minutes. This is allowed to settle and then drawn off the bottom of the washer. The chlorohydrocarbon is then further washed with pure water two or three times for 10- or 15-minute periods. The washed hydrocarbon is then run into the fractionating still. The first fraction coming over, consisting of untreated pentane, is run back into the pentane storage for further chlorination. The amyl chloride cut is the fraction coming over between 90" and 110" C. This fraction amounts roughly _- - to 25 per cent of the original liquid, depending upon the conversion d u r i n g chlorination, and is approximately 80 per cent pure amyl chloride. The residue amounts to about 5 per cent and consists of the di- and trichlor derivatives. The amyl chloride recovered is run back into the washer and rewashed with pure water before further treatment. F i g u r e 1-Apparatus f o r C h l o r i n a t i o n of P e n t a n e
Conversiorl Of Amy1 Chloride to Amyl Acetate
Numerous difficulties were encountered in developing this step of the process, chief of which was the tendency of the amyl chloride to decompose to form amylene and hydrochloric acid vapors according to the reaction, C6HiiCl+
CsHio
+ HCI
This tendency was finally overcome or reduced to a minimum by the elimination of all moisture from the ingredients used in the reaction, and the int r o d u c t i o n of c h a r c o a l in the reaction as a ~ a t a l y s t . ~Identical samples of amyl chloride and sodium acetate, except that in one case carbon was present, were boiled and refluxed for 8 hours. I n the test without carbon the amyl chloride was 70 per cent, decomposed to amylene, while in the test using carbon decomposition amounted to only 18 per cent. Table I1 shows the effect of carbon on amyl acetate yield. ESTERIFICATIOX-The amyl chloride-is charged-into a 100or 200-gallon steel-jacketed, agitator-equipped autoclave, along with 65 t o 75 parts by weight of fused and ground (100 mesh) sodium acetate and 1 t o 2 parts by weight of solvent. Heat is applied to the autoclave by circulating hot oil through the jacket. A temperature of 400" t o 450" F., with a corresponding pressure of 200 t o 250 pounds gage, is maintained on the apparatus. The time required to com4
U.S. Patent 1,374,666 (April 12, 1921).
443
plete an esterification is about 8 hours a t maximum heat; a complete cycle, including charging, esterifying, and discharging, requiring about 12 hours. The start of the reaction is manifested by a gradual drop in pressure and completion of the reaction is evidenced by a decided drop in pressure which is only slightly affected by increased temperature. This esterified product is distilled directly from the autoclave through a condenser into a washer, where it is washed and neutralized with pure water of sodium carbonate. T a b l e 11-Comparative
RUN
Y i e l d s of A m y l A c e t a t e w i t h and w i t h o u t Activated Carbon DURATION O F RUN
Hours
AMYLACETATEY I E L D
Minutes
Per cent
NO CHARCOAL
7
1 2 3 4
6
37.16 29.15 45.16 33.42
40 30
7
20
7
CHARCOAL U S E D
5
58.16 83.23 78.34
30 15
6 7
Recovery of Amyl Acetate
After washing, the esterified liquid is run into a fractionating still and fractionated into three fractions as follows: CUT
TEMPERATURE
FRACTION
c. 1 2
I. b. p .
3
120 t o l i 5
t o 82
82 t o 120
Amylenes, pentanes, etc. Unconverted amyl chloride, some amyl. butyl, and perhaps propyl acetate' Amyl acetate, 99 to 100 per cent
This cut is used as starting solvent in charging the autoclave; it might also be used as a cheap grade of solvent.
The amyl acetate recovered in cut 3 is a technical grade product but can be purified by redistillation and washing. Without purification it shows the following physical properties : Specific gravity a t 15.5O C . , . . . . . . . . . . . . . . . . . . 0.88 C o l o r . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Light yellow . . . . . . . . . . . . . None . . 0 . 1 9 6 per cent acetic acid t . . . . . . . . . . . . 930 c. . . . . . . . . . . . . . . 2000 c. . . . . . . . . . . . . . None
These specifications compare favorably with technical grades of cold-process amyl acetate purchased on the open market. Methods of Analysis of Amyl Acetate
Some difficulty was experienced in finding a method suitable for the estimation of the per cent of amyl acetate formed in the esterification of the chlorohydrocarbons. Several methods were tried, saponification before and after esterification, difference in chloride content before and after esterification, and iodine absorption. Saponification with alcoholic potassium hydroxide and titration with standard hydrochloric acid to determine the percentage of amyl acetate gave widely varying results, owing to the action of the alcoholic potassium hydroxide on the hydrocarbon, producing amyl alcohol. The results obtained varied with the duration of the saponification. The method of Drogin and Rosanoff for the detection and determination of the halogens in organic compounds was tried, but owing to the presence of di- and trichlorides and some butyl and heptyl chloride, considerable error was introduced by figuring chloride content to amyl chloride disregarding its homologs. The same difficulty was experienced in getting iodine absorption values. Iodine was absorbed not 5
J . A m . Ckem. Soc., 98, 711 (1916).
INDUSTRIAL AND ENGINEERING CHEMISTRY
444
only by the olefins, but by other substances, consequently the results obtained were false. As a result of these difficulties a method was tried out which had for a basis the solubility of amyl acetate in sulfuric acid and the relative insolubility of the chlorohydrocarbons and saturated ring compounds of the polymethylene series and paraffin hydrocarbon.6 T a b l e 111-Synthetic AMYLACETATE
M i x t u r e of C h l o r o p e n t a n e and A m y l A c e t a t e ACETATE CHLOROPENTANE BY AMYL ABSORPTION T~~~
Per cent
Per cent
Per cent
100 90 80 70
0 10 20 30 40 50 ti0
100.0 90.4 80.0 70.2 59.8 51.4 38.8 31.0 21.0 9.2 0.0
ti0
50 40 30 20 10 0
70
80
90 100
Two hundred cubic centimeters of the esterified product from the autoclave were placed in a standard Bureau of Mines distillation apparatus and distilled slowly, about 2 drops a second. Cuts were made of each 10 per cent fraction, temperature readings being made a t the beginning, middle, and end of each cut. Each cut was kept separately in tightly stoppered bottles to prevent volatilization. Upon the completion of the distillation, a sulfuric acid absorption test was run on each cut in a 10-cc. glass-stoppered graduate, as follows: By means of a pipet 5 cc. of C. P. 1.84 gravity sulfuric acid were introduced into the graduate, and 5 cc. of the cut being tested were introduced by means of another pipet, care being taken to avoid mixing the two layers until the stopper was inserted in the graduate. After inserting the stopper, the content of the cylinder was violently shaken for 5 minutes. After settling 15 minutes, the total volume was read and the point of separation of the layers noted. The absorption per cent is calculated as shown in the following example: For the purpose of a test example, 50 per cent Merck's pure amyl acetate and 50 per cent chloropentane were mixed together and a n absorption run on the mixture. cc. 5 5 10 7.51 9.77 2.23
Let A = Acid layer before agitation B = Sample layer before agitation C = Total volume before agitation D = Acid layer after agitation E = Total volume after agitation F = Total volume minus acid layer F = volume of sample unabsorbed Volume of sample used = 5 cc. - F = absorbed oil; in this case, 2.77 cc. or 55.4 per cent pure amyl acetate
It was found that, although in 15 minutes the separation is almost complete, on standing 24 hours about 0.1 cc. more comes out of solution. The following formula was derived to take care of this error: Corrected absorption = per cent a t end of I 5 minutes - (3 f per cent found X 0.02); in this case (55.4 x 0.02)l = 55.4 - [3 55.4 - 4.11 = 51.3 per cent, which is within 1.3 per cent of the actual amyl acetate present
+
I n running a complete analysis, absorptions are run on each of the 10 per cent cuts of the esterified product and by plotting the corrected absorption per cent of each cut against the middle boiling point of each cut, the per cent of amyl acetate can be determined. The widest variation found on synthetic mixtures of amylenes, chlorohydrocarbons, and amyl acetate was 2 per cent of the correct value. (Table 111) 6
U. S Patent 1,278,198,
Vol. 19, No. 4
Cost Figures
Apparatus and Buildings (Basis 500 gallons amyl acetate per 24 hours) BUILDINGS APPROXIMATE COST Still h o u s e , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $4000 Chlorination building. . . . . . . . . . . . . . . . . . . . . 2000 Autoclave building,. . . . . . . . . . . . . . . . . . . . . . 1500 Power h o u s e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1000 Refrigeration plant. . . . . . . . . . . . . . . . . . . . . . . . 1000 Warehouse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1000 Office a n d laboratory,. . . . . . . . . . . . . . . . . . . . . 1500 APPARATUS Gasoline Fractionation: 1 Pentane still comolete with condensers. refluxes,'etc. . . . .................... $5000 2 Gasoline tanks (5000 gallons), . . . . . . . . . . 2500 2 Pentane tanks (2000 gallons). , , . . , . . , . . 1200 Chlorination : 30 Chlorination units complete with racks, condensers, etc. ....................... $1500 2500 1 Chlorination control panel complete,, . . , 1 HC1 scrubber . . . . . . . . . . . . . . . . . . . . . . . . . 100 1 Mechanically stirred washer. .., 750 2 T a n k s (1000 gallons) . . . . . . . . . . . . . . . . . . 900 Lead ,piping and miscellaneous valves a n d piping... 1000 Recovery of Amyl Chloride: 1 Enamel-lined still complete with condensers, etc. . . . . . . . . . . . . . . . , .. $2500 Miscellaneous piping . . . . . . . . . . , . . 150 1 T a n k (1000 gallons). . . . . . . . . . . . . . . . . . 450 Esterification: 3 Autoclaves,. . . . . . . $7500 1 Condenser., . ...... 250 750 1 Mechanically stirred washer,. . . . . . . . . . . . . . . . . . 6000 1 400,000 B.t.u. oil heater.. 1 Sodium acetate fusing pan . . . . . . . 200 1 Sodium acetate grinder., . . . . . . . . . . . . . . . 750 300 1 Sodium acetate cyclone.. . . . . . . . . . . . . . . 450 1 Tank and support,. . . . . . . . . . . . . . . . . . . . Miscellaneous piping. .................... 300 Recovery of Amyl Acetate: 1 Enamel-lined still complete' with condensers, etc. $2500 2 T a n k s (1000 gallons). . . . . . . . . . . . . . . . . . . 900 AUXILIARYPLANT 2 Boilers,, , . . . . . . . . . . $2000 . . . . . . 3600
I..
............................
..
...........
Warehouse e
..................
$ 300 1000
__ Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $57,650 Add labor, piping, e t c . , . . . . . . . . . . . . . . . . . . . . . . . . . . 50,000
$107,650
Contingent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Total for apparatus and buildings.. . . . . . . . . . . . . . . . . . . . . .
20,000 $127,650
Production Data High-test gasoline. . . . . . . ..................... Recoveries: Pentane, 40 per c e n t , , . . . . . . . . . . . . . . . . . . . 1200 gallons Residue, 30 per c e n t , , . . . . . . . . . . . . . . . . . . . 900 gallons Loss, 30 per c e n t . ,
..................................
3000 gallons
2100 gallons 900 gallons
Chlorination of Pentane: 1200 gallons pentane 75 per cent recovery = 900 gallons 900 gallons chloropentane 25 per cent recovery of 80 per cent amyl chloride = 225 gallons B y rechlorination of the untreated pentanes distilled off when separating the amyl chloride from the chloropentane, the ultimate yield of amyl chloride this case, is approximately 40 per cent of the original pentane treated-in 480 gallons. Esterification : 480 gallons 80 per cent amyl chloride . . , . . , . . 106.57 Molecular weight amyl chloride.. . . . . . . . . . 130.14 Molecular weight amyl acetate.. . . 0,8834 Specific gravity amyl chloride. . . . . . . . . . . . . . . . . . . . . . . 0,8659 Specific gravity amyl acetate.. . . . . . . . . . . . . . . . . . . . . . 1 0 6 . 5 7 p o u n d s , . , . , , , . . , = 1 4 . 5 gallons 1 3 0 . 1 4 p o u n d s . . . . . . . . . .= 18 gallons Theoretical recovery.. ... 125 per cent 125 per cent recovery, . . . = 600 gallons SO per cent conversion to amyl acetate = 4 $240.00 1200 gallons pentane a t 20 c e n t s . . . . . . . . . . . . 120.00 2000 pounds chlorine a t 6 cents. . . _. . . . . . . . . 3000 pounds sodium ac c e n t s . . . . . . . . . . . . . . . . . 150.00 26.40 Depreciation, 10 per ce ...................... 30.00 Power a n d fuel. ....... ....................... 75.00 Labor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Total, . . . . . . . . . . . . . . . .................... Selling, packing, insurance, contingent and overhead..
.....
$641.40 75.00
$716.40 Total cost of 480 gallons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $1.50 Total cost per gallon.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.75 Selling price of amyl acetate per gallon, . . . . . . . . . . . . . . . . . . . . . . . . Profit per gallon..
........................................
-
$0.25
April, 1927
IND USTRIAT, AND ENGINEERING CHEMISTRY
A seinicommercial plant was built from which the foregoing figures were deduced. Owing, however, to the introduction to the trade of other solvents and particularly those coming from the olefins of cracked gases, larger scale Operations have not been attempted yet* It is known, however, that with more work on the process, and a larger
445
operation than that presented, costs can be very materially reduced so that the process still has attractive possibilities. Acknowledgment
Various individuals have contributed material to the solution of this problem, among therrl p. Lf. Biddison, G. C;. Oberfell, H, T. Boyd, and c, L, J - ~ ~ ~ ~ ~ .
Recent Developments in Zeolite Softening‘ By A. S. Behrman I K T E R N A T I O NFILTER AL Co., C H I C A G O ILL ,
Early Types
period of regeneration was also lengthy. It was the standard practice to require a softening period of 8 t o 12 hours, and a regeneration period of similar duration. his researches on fertilizers. Rather interestingly he Obviously, with such slowacting zeolites, high peak describes the synthesis of zeolites by two of the same re- loads and suddenly increased demands for soft water could actions used today-i. e., the reaction of sodium silicate be met only by the alternative expedients of using an appawith sodium aluminate on one hand, and with aluminum ratus large enough t o have a normal capacity equivalent sulfate on the other. to the Deak load reauired. or bv providing sufficient storage bf water softened a t the The first effort to utilize slower rate to carry over the commercially the base-expeak period. Either alterchange property of zeolites The demands upon the modern zeolite water softener native had its obvious obwas made by who are considerably more exacting than those made on jections. used a siliceous earth for the its predecessors. Chief among these demands are Another objection to the renioval of potash from beetgreater softening capacity per given volume of zeolite, f u s e d t y p e of synthetic sugar juice, in order to inmore rapid rate of base exchange, and a minimum loss zeolite was its susceptibility crease the yield of crystalof water pressure through the zeolite bed. to attack by certain kinds lizable sugar. A good deal A distinct advance in the attainment of these objects of water, particularly those of work was done along the has been made possible by the development of the with large amounts of free same line, and apparently synthetic “gel” type of zeolite, which is the principal carbon dioxide. The effect much more scientifically, subject discussed in this paper. A brief review of preof this attack was a gradual by Rumpler,4 who worked vious practice and materials is also given. disintegration of the zeolite with synthetic precipitated into more or less gummy zeolites and those occurring and gelatinous p a r t i c l e s in Portland cement. The application of zeolites to water purificat’ion did not which were unsuited mechanically a s well as chemically receive attention until the first decade of the twentieth for water-softening. A few years after water-softening with these synthetic century. There appears to have been some little: discussion between Rumplerj and G a m 6 as to who should get credit zeolites was introduced into the United States, a bentonitic for the suggestion; but this argument does not concern us clay was found which possessed marked base-exchange properties. This clay, when processed into particles of here. Regardless of whether Rumpler or Gans suggested water- appropriate size, baked and rehydrated, yielded a T-ery softening with zeolites, it is fairly certain that Gans and his satisfactory softening material-satisfactory again, by the organization made t’he first usable synthetic materials then prevailing standards, since it was also a relatively that were actually employed for the purpose on a practical slow softening, slow regenerating material, with attendant scale; and in 1906 they obtained a process patent7 for the limitations. softening of water by means of zeolites. The zeolites used The next development in zeolite water-softening, which were made by fusion of appropriate raw materials. After was fast becoming a keenly competitive field of chemical the usual period of experimentation, products were finally engineering, was the introduction of Kew Jersey greensand, obtained which were generally satisfactory according to or glauconite, as the softening medium. This marked a the only standards then prevailing. distinct advance, for greensand is much more rapid in its These zeolites, however, were quite slow acting. I n action than either of the older zeolites, so that considerably consequence, wat’er could be run through a bed of such greater softening rates and much shorter regeneration periods material only a t a comparatively slow rate if complete could be employed. High peak loads could be carried, softening was to be vecured; and by the same token the making unnecessary the use of extra softening or storage capacity. It is true that the useful capacity of greensand Presented before the Division of Water, Sewage, and Sanitation between regenerations was materially less than that of the Chemistry a t the 72nd Meeting of the American Chemical Society, Philaolder materials-about 3000 grains of calcium carbonate delphia, Pa., September 5 to 11, 1926. equivalent per cubic foot as compared with 4000 to 5000 J. Roy. Agr. S o c . , 11, 313 (1850); 13, 123 (1852). 8 German Patent 95,447 (June 2 , 1896). for the older materials-but regeneration could be accom4 Deut. Zuckerind., 26, 585, 625 (1901). plished in such a short time-a half hour, or even somewhat 6 Centr. Z u c k e r i n d . , 16, 172 (1907--08). less-and with such economy of salt, that the lesser total 6 I b i d . , 16, 373 (1907-08). capacity was of comparatively small importance. ’ German Patent 197,111 (1900).
T
HE base-exchange properties of zeolites were discovered by ,J. Thomas Way2 in 1850, in the course of
1
2
