Jul;\-, 1932
ISDUSTRIAL AKD ENGINEERIKG CHEMISTRY
Large-scale tests were conducted in 1930 a t a number of southern mills to compare the effectiveness of the more promising compounds and to perfect practical methods of application. Additional small-scale tests were conducted to make a further study of these promising compounds in different modifications and to compare them with new chemicals which had not previously been tested. The results of some of these studies are now published (4, 6). The records of these experiments agreed with the previous preliminary tests in proving the ethylmercury compounds to be the most generally effective chemicals used. A solution containing 1 part of either of the ethylmercury salts in 10,000 parts of water proved to be an effective dip for the control of' sap stain of both pine and gum. A few other compounds, when used in greater concentration than this, were found to be effective on certain kinds of lumber, but none of them appears to be satisfactory on both pine and gum. Borax and sodium tetrachlorophenolate were effective on sap gum but not satisfactory on pine, while sodium o-phenylphenate was effective on pine but not sufficiently effective on gum. The extensive large-scale tests in 1930 indicated that the ethylmercury compounds could be used successfully for dipping lumber on a commercial scale for the control of sap stain. Ethylmercury chloride was then offered the lumber industry, diluted sufficiently with water-soluble inerts to make it safe to handle by exercising the precautionary measures recom-
747
mended for handling poisonous disinfectants. The concentration is adjusted so that 1 pound in 50 gallons of water gives the required strength for application. This solution is prepared in a vat so constructed that the lumber passing on the green chain from the saws to the sorting and grading floor is drawn through the solution. A thorough wetting of all surfaces of the lumber is all the treatment necessary. Although not entirely beyond the developmental stages, ethylmercury chloride is producing good results in the control of sap stain of lumber, and is filling a real need in the lumber industry. LITERATURE CITED (1) Brundage, M. R., Am. Lumberman, 41 (April 5, 1930). (2) Ezekiel, W.N., and Taubenhaus, J. J., Ph2/topathoZogy, 21, 1191 (193 1). (3) Lindgren, R. M., and Chapman, A. D., Am. Lumberman, 46-8 (June 13. 1931). (I) Lindgren, R. M., a n d Scheffer, T. C., Southern Lumberman, 42-6 (Feb. 1, 1931). (5) Lindgren, R. M., and Scheffer, T. C., Am. Lumberman, 35-8 (March 7 , 1931). (6) Stucky, H. P., Ga. Expt. Sta., Ann. Rept. 41, 24 (1928). (7) Tisdale, W. H., and Cannon, W. N., Phytopathology, 19, 80 (1929). (8) Townsend, G. R., Ibid., 22, 2 i (1932). RECEIVED January 29, 1932.
Hydrogenation of American Goals Preliminary Investigation M'. L. BEUSCHLEIN, B. E. CHRISTENSEN, AND C. C. WRIGHT Chemical Engineering Laboratory, University
of Washington, Seattle, Wash.
T
HE increased demand for
that with most coals, ferric oxide For the conditions investigated, coal ash does liquid fuels during the reacts a not appear to act as a catalyst for the hydrogensSince the pioneering work of past decade has stimution Oj'phenol at 400" C. The "B" product hUS ~ ~much research ~ has ~ beeni lated research having as its object the conversion of coal into been found in the two coals before and after carried on in Great Britain by the more desirable liquid prodhydrogenation. Qualitative and quantitative the Fuel Research Board and by w t s . The m o s t p r o m i s i n g &la have been presented for hydrogen absorption the Mines Research Laboratory by two ~~~~i~~~ coals the bituminous class. (Birmingham). Inaseriesofexmethod d e v e l o p e d is that of high-pressure hydrogenation. periments a t the Mines Research Temperatures between 300" and 350" have The first att)empt to hydroLaboratory a study was genate coal was made by Berthebeen found to giae optimum conversion of the madeof coal hydrogenation, both lot (4) some sixty years ago. coals into phenol-soluble constituents. The with and without catalysts. conversions of these coals at optimum conditions Bergius' process was used withHe treated finely powdered coal favorably with those reported f o r E ~ ~out ferric ~ -oxide or other catawith a saturated hydriodic acid solution a t 270" c. for several lysts, and with a change of dispean coals. hours. This method was later persion m e d i u m . From r u n s covering twenty-nine different modified by Tropsch (g), who added red phosphorus to the reaction mixture and found in coals, data were obtained that showed some conversions in general that the younger coals were quite susceptible to excess of 80 per cent. With nickel oxide or ammonium hydrogenation. For most of the pioneering work and the molybdate catalysts, some of the same coals showed conversuccessful commercial application, however, credit is given to sions greater than 90 per cent. Rergius, who succeeded in producing virtually complete I n Italy similar experiments have been conducted by liquefaction of coal. The process, as described in his patent Levi, Padovani, and Amati (IS), in Japan by Oshima and (d), involves treatment of coal with hydrogen a t high pressure Tashiro (16), and in France by Arend (1). For the investiand at temperatures between 300" and 500" C. The patent gat,ion of Canadian coals, a laboratory has been inst,alled a t specifies dispersion of coal in liquid hydrocarbons; although the University of Alberta (17). Except for some work on it mentions no catalyst, ferric oxide is used in the process, Canadian coals reported by Graham ( I l ) , results of hypresumably for the purpose of fixing the sulfur present. drogenation studies on American coals do not appear in the -More recent investigation by Skinner (,?O),however, shows literature.
c.
~
I N D U S T R I A L A N D E NG I X E E R I N G C H E M I ST R Y
748
TABLEI. RESULTS OF PHEYOL HYDROGESATION ASD EXTRACTIOX ASD EXPERIMENT
TEMP.
RGN A C. Lb./sq. in. K g . / s q . cm. %
Phenol hydrogenation 400 Coal extraction: Eastern 50 Western 50 Constant-vol. nitrogen:" Eastern 350 Western 350 Constant-vol. hydrogen:a Eastern 350 Western 350 a Pressures for constant-volume
PRESSURE
PRODUCTS----
B
COXSTANT-VOLUME EXPERIMENTS
OF
E
Vol. 24, No. 7
F
CARBOS 1 B
HYDROGES RATIOC / H A B 1 B % % ... , . . .. ..
%
%
D %
%
%
%
225
1
0
0
0
0.9
0.2
0
..
%
3200 14.7 14.7
1.03 1.03
2 3
86.1 85.1
10.2 7.6
3.7 5.4
0 0
0 0
0 0
81.8 79.0
80.3 78.1
4.7 5.2
4.6 4.9
17.4 15.2
17.5 16.6
1700 1750
120 123
4 5
83.8 7i.5
3.4 4.3
8.2 10.2
0.3 0.3
0.: 0.t
3.6 5.4
86.4 84.0
81.7 83.0
3.6 4.0
4.2 4.5
23.8 21.0
19.6 18.6
1700 1750
120 123
E
40.8 40.6
42.2 23.7
15.4 14.7
3:4
316
9.4 26.5
85.2 83.1
83.6 83.5
3.7 3.8
4.1 4.2
23.0 21.8
20.4 19.6
I
C
..
experiments reported as initial pressure at room temperature,
PRESENT INVESTIGATIOS Studies of American coals were begun in the fall of 1930 a t the chemical engineering laboratories of the University of Washington. The first work was confined to representative bituminous coals from both the eastern and western sections of the United States, and the final selection of samples was dependent upon these and other available analytical data of the respective coals. The experimental system adopted differed from that of other investigators in one respect: the reaction bomb was of the stationary type and employed no stirring device. Graham, heating externally by means of a gas flame, used a rotating bomb; Bergius, in his American patent, specifies a revolving stirrer in the reaction mixture. The selection of a dispersion medium was conditioned largely by available methods of analyzing the products. Bergius used a saturated oil and separated the products by a combined process of extraction with raw petroleum and destructive distillation. Fischer (7, 8) used no dispersion medium and analyzed the products by both ether extraction and destructive distillation. Shatwell and Iiash (19) used saturated oils, but were unable to effect a satisfactory separation of the products from the oil used. Shatwell and Graham (18) used phenol and worlred out a separation of products depending upon phenol and chloroform extractions. I n general, the yields obtained by workers using no dispersion
gen gas instead of nitrogen. After these initial runs, the coals were hydrogenated at constant pressure between the limits of 250" and 450" C., and 120 and 296 kg. per square centimeter (1700 and 4200 pounds per square inch) pressure, with phenol as the dispersion medium. The samples of coal selected were received from the United States Bureau of Mines. The eastern coal, furnished through the courtesy of A. C. Fieldner, was a p-bituminous sample (Seyler's classification) from the Ocean KO.2 mine, Pittsburgh bed, Allegheny County, Pa. This coal analyzed as follows (6): K L T I Y A T E .4KALYSISn
(70)
C
H
0
S
N
85.4
5.9
5.9
1.1
1.7
PROXIMATE ANALYSIS
(70) FIXEDCARBOS
VOLATILE MATTER 37.6
62.4
LOW-TEMPERATURE C A R B O N I Z I T I O N ,
COKE
GAS
7i.6
7.1
bWo C. (%)
TAROIL
LIQUOR
8.5
6.3
Softening temperature of coal 320' C. Initial temperature of active decomposition 390' C. 8 1 1 results reported in this paper are expressed on the ash-free and moisture-free basis. Q
The western coal, furnished through the courtesy of H. F. Yancey of the United States Bureau of Mines, University of Washingt,on station, wvns a per-m-lignitous sample from KO.3 mine, Roslyn bed, Rosyln, Wash., and analyzed as follows (21): (%)
CLTIMATE A N L Y S I S
NITROG€N
S500
C
H
82.6
6.3
0 8.5
P R O X I l l A T E .4XIALYSIS
s
N
0.5
2.1
(70) FIXEDCARBON
VOL.ATILE MATTER
56.3
43.7 L O W - T E M P E R A T U R E C h R B O K I Z . ~ T I O N , 550'
C.
(%)
COKE
GAS
TAR
LIQUOR
70.1
6.42
17.9
5.05
LABORATORY IKSTALLATIOS. Briefly, the system employed
0
P
+
lY0UR.s
e
OF NITROGEN AID FIGURE1. CHANGEOF PRESSURE HYDROGEN W-ITH TIME (EASTERN COAL)
10
OF
medium were unsatisfactory. The method of separation effected by Bergius, although more applicable industrially, does not yield as complete information of the coals as does the method of Graham. Phenol was therefore adopted as the dispersion medium. Initial experiments were made upon the hydrogenation of phenol in the presence of a small amount of coal ash. This work was followed by phenol extractions of the raw coal. Both coals were then subjected to a constant-volume nitrogen distillation a t 350' C. and 211 kg. per square centimeter (3000 pounds per square inch) pressure, with phenol as the dispersion medium. Similar runs were made with hydro-
a stationary reaction chamber involving no stirring. It was heated electrically by means of an external coil. A thermocouple well passed through the head and was immersed in the
reaction mixture. Controls from the hydrogen storage cylinders to the reaction chamber were so situated that runs could be made at either constant pressure or constant volume. Pressures up t o 350 kg. per square centimeter (5000 pounds per square inch) were obtained by means of a three-stage compressor which received the gas from a gas holder at atmospheric pressure. From the compressor the gas passed through a felt-packed oil trap to the storage cylinders. EXPERIMENTAL METHOD.The reaction cylinder was charged with an intimate mixture of 50 grams each of coal and phenol. The cylinder was placed in the reaction bomb, which in turn was connected t o the high-pressure system. A buffer cylinder was brought to the ressure of the desired run and opened to the control manifolt which in turn opened to the reaction chamber. The apparatus was then ready for a constant-pressure run. The desired temperature of the reaction chamber was attained and maintained for a period of 8 hours. At the end of a run,
July, 1932
I N D U S T R 1-4 L ,4 N D E N G I N E E R I N G C H E Jl I S T R Y
the heat was shut off; the system was closed to the pressure line and then allowed to cool to room temperature. The gas was then passed through sampling bottles and measured by a uet meter. The charge was removed and analyzed. In order to make comparisons between European and American coals, Graham's method was followed, and a separation was made into the following fractions: A. B. C.
D
E.
F.
Residue insoluble in phenol Fraction soluble i n phenol, insoluble in chlorofoim Fraction soluble in phenol and chloroform Light oil boiling under 150' C. Water Gas
DETAILSOF SEPARATIOS.The liquid portion was distilled up to 150" C. and the distillate was washed successively with dilute sodium hydroxide, dilute sulfuric acid, and water. The solid portion, together with the stripped liquid portion, was treated with an excess of sodium hydroxide solution to remove the phenol. The solid was filtered, ,ground in a mortar, washed with sodium hydroxide and finally with water, then dried in z'acuo a t 105' C., and weighed. This procedure gives the total weight of the products A , B, and C. The mixture was then placed in a Soxhlet extiactor and extracted with phenol. The phenol-insoluble residue from the thimble was leached with a 20 per cent solution o f sodium hydroxide, washed with water, and dried in vacuo, giving product A . The phenol solution was treated with a slight excess of sodium hydroxide solution which caused the precipitation of a black tarry mass. This precipitate was filtered, washed, and dried, then placed in a Soxhlet extractor, and extracted with chloroform. The portion remaining in the thimble after extraction was product B. The chloroform was removed from the extract by evaporation on a steam bath, leaving product C. Combustion analyses were made for carbon and hydrogen on all the A and B products and on a few of the C products. -4nalysis of the gaseous products was made in some cases.
DISCLXSION OF RESULTS In Table I are summarized the results of phenol liydrogenation, of phenol extraction of enstern and western coals, and of the constant-volume nitrogen and hydrogen experiments. iiccording to Lush ( l 5 ) ,phenol is not an appropriate dispersion medium for coal hydrogenation because, under the conditions prevailing, it is readily converted into cyclohexane. Wing and Florentin (12), however, claim that phenol is not hydrogenated without the use of catalysts. I n a test reported by Shatwell and Graham (18) in which phenol was treated for 4 hours under a hydrogen pressure of 134 kg. per square centimeter (1900 pounds per square inch) and a t a temperature between 400" and 406" C., no conversion of the phenol was observed. The catalytic effect of coal ash upon the hydrogenation of phenol, however, does not appear to have been reported in these or other investigations. Run 1 of the present investigation (Table I), in which phenol was treated with hydrogen in the presence of a small quantity of coal ash, shows very little hydrogenation at 400" C. I n this experiment, phenol was hydrogenated in the presence of one per cent of A product from the Roslyn coal. This product contained 42 per cent ash of the following composition (-5): silica, 41.6 per cent; alumina, 39.3 per cent; ferric oxide, 10.3 per cent; calcium oxide, 7.9 per cent; magnesia, 1.3 per cent; and phosphorus, 0.62 per cent. I n correlating the results from phenol extractions of the coals with those from nitrogen and hydrogen experiments at constant volume, several interesting observations regarding hydrogenation were noted. The B product yields of 10.3 and 7.6 per cent from phenol extractions of eastern and western coal, respectively, show that this fraction, although one of the principal ones resulting from hydrogenation, is not solely due to the action of hydrogen, but is present in the original coal. These results do not substantiate those of Graham ( I O ) , who states that the B fraction is a definite product of hydrogenation. The effect of temperature alone is clearly shown in a comparison of the phenol extractions with the nitrogen euperiments. Both coals under the action of increased
749
temperature showed a small decrease in A , a large decrease in B, and a greatly increased yield of C. These results indicate that temperature increase has only a slight effect upon the A product but exerts a marked cracking action on the B portion, tending to break it into lighter components. Figures 1 and 2 illustrate the change of pressure with time when the coals were heated in atmospheres of nitrogen and of hydrogen. These curves were obtained under constantvolume conditions and indicate qualitatively the effect of temperature rise and of hydrogenation. A quantitative measure of the hydrogen absorbed is shown in Table I1 and amounts to 1.6 per cent for the eastern and 2.8 per cent for the western coal. Because the cracking of the coal liberates
zoool 0
2
4
HOURS
6
FIGURE 2. CHARGE OF PRESSURE OF NITROGEN.4hD OF HYDROGET UITH TIME(WESTERNCOAL) gases, progressive increases in pressure for experiments with nitrogen are to be observed. Hydrogenation experiments under identical initial conditions, however, show a marked decrease in pressure which clearly indicates hydrogen absorption. Both hydrogen curves, moreover, show definitely that the absorption is more rapid in the early stages of the experiment and becomes almost negligible toward the end of the runs. Furthermore, the product percentages reported in Table I for these experiments shorn that the hydrogen reacts not only with gaseous and phenol-soluble products, but also with the solid coal. TABLE11. HYDROGEN ABSORPTION FOR CONSTAST-\-OLUME EXPERIMENTS (Volume in litera a t normal temperature and pressure) ------EARTERN COAL7 - W ~ COAL-~ ~ NITROGEN EXPT
HYDROGEN EXPT.
Total Total Total Total gas gas H N Initial 26.1 2 6 . 1 20.1 26.1 Final 29.8 26.3 2 3 . 9 17.9 Absorptiona ., ., .. 1.6 a Grams hydrogen per 100 grams coal.
HITROGEN EXPT
HYDROGEK EXPT
Total Total gas N 28.8 2 8 . 8 34.0 29.0
Total Total
.
..
gas
~
H
2 8 . 8 28.8 2 4 . 8 15.8 .. 2.8
Bergius ( 3 ) observed that hydrogenation began a t a temperature relatively low, and that treatment a t temperatures between 300" and 350" C. for several hours resulted in a fairly large absorption of hydrogen, although the product was a solid pitchlike mass. Continued treatment at 450" C. converts this product to a liquid. Levi, Psdovani, and Mariotte (14) state that hydrogenation takes place in three stages: (1) Up to 300' C., transformations occur without the formation of gas or vapor, and with very little hydrogen absorption. (2) Between 350" and 400' C., hydrogenation is principally of the liquid phase and corresponds essentially to destructive distillation. (3) From 400' to 500" C., cracking of more resistant molecules takes place with hydrogenation essentially in the vapor phase.
~
~
INDUSTRIAL AND ENGINEERIXG CHEMISTRY
750
TABLE111. EFFECTOF TEMPERATURE ON HYDROGENATION OF COAL PRES0URE
L 6 . / s q . in. K g . / e q . em.
RUN
TEMP. C.
PRODUCTS
C
D
E
%
%
%
%
A
B
%
CARBON B % %
AHYDRoGEN B
A
%
%
B
EASTERN COAL
2200
155
250 300 350 400
8 9 10 11
83.8 39.5 33.8 50.7
16.7 49.9 51.5 20.6
5.3 10.5 14.0 14.8
..
...
3:l 1.6
3.7 4.0
...
81.7 83.0 82.5 88.7
82.4 82.0 83.0 85.0
4.3 4.4 4.0 3.6
4.5 4.5 4.3 3.7
19.0 18.8 20.2 24. t
18 2 18.3 19.8 22 6
0.4 0.0 0.7 2.3 4.2 13.1
0.3 1.8 4.3 3.6 4.3 3.8
82.2 81.1 84.9 86.1 87.8 90.7
85.9 81.8 81.1 81.7 82.5
..
4.4 4.0 3.7 3.6 3.5 3.2
4.3 4.5 3.5 4.2 3.9
...
18.7 20.2 23.0 23.9 25.0 28.1
20.0 18.2 23.2 19.5 21.1
81.3 83.2 88.0 90.0
82.5 80.0 83.5 85.0
4.6 4.7 3.9 3.5
4.7 4.4 4.0 3.8
17.7 17.5 22.6 25.7
17.4 18.2 20.8 22.4
... ...
79.6 81.2 82.1 86.4
81.2 81.0 83.8 85.1
5.3 4.8 4.2 3.6
4.9 4.6 4.6 4.0
15.2 17.0 19.6 24.0
16.7 17.6 18.2 21.2
...
78.3 75.7 79.4 86.3 89.3
79.8 81.4 80.4 82.1
..
5.0 4.6 4.6 3.8 3.5
3.0 4.5 4.3 4.9
..
15.7 16.6 17.3 22.6 25.7
16 1 18.3 18.7 16.8
...
79.0 79.6 84.5 87.3
79.9 79.3 84.2 83.6
5.1 4.6 3.6 3.6
4.8 4.6 4.3 4.0
15.5 17.2 23.4 24.2
16.6 17.1 19.6 20.9
3200
225
250 300 350 400 450 500
16 17 18 19 20 21
75.0 21.1 34.5 69.7 78.5 92.3
8.2 67.9 31.4 10.3 3.3 0.0
14.8 12.2 34.9 12.9 10.1 7.1
4200
295
250 300 350 400
27 29 28 30
87.1 42.3 27.6 53.3
13.7 47.5 40.2 10.4
8.3 10.2 14.1 11.1
12 13 14 15
81.8 52.9 26.1 54.4
19.3 36.8 58.0 9.4
6.5 10.0 21.1 13.4
29.7 66.8 59.7 27.6 1.6
5.3 22.4 14.4 5.5 5.4
13.0 21.2 34.0 9.5
6.7 7.9 13.1 9.8
0:s 2.7 6.4
...
1.9 3.6 4.3
W E S T E R N COAL
2200
155
250 300 350 400
'
3200
4200
295
250 300 350 400
31 32 33 34
85.9 66.1 37.6 46.5
..
..
...
3:O
3.4
0:O
1.3 4.2 3.9 4.3
2.6 2.7 12.2 0:2
3.7 3.5
1.0 2.9 3.1
TABLEIV. EFFECTOF PRESSURE ON HYDROQENATION OF COAL TEMP.
c.
PRESSURE L b . / s q in. K q . / s q . cm.
RCN
%
B %
A
PRODUCTB
D %
C %
E %
A
%
CARBON B %
HYDROGEN A B
%
%
RATIOC/H A
B
E A S T E R N COAL
350
1700 2200 2700 3200 3700 4200
120 155 190 225 260 295
35 10 36 18 37 29
84.4 33.8 35.7 34.5 30.0 27.6
62.7 51.5 53.3 31.4 50.0 40.2
15.1 14.0 11.5 34.9 16.1 14.1
1700 2200 2700 3200 3700 4200
120 155 190 225 260 295
38 14 39 24 40 33
37.5 26.1 17.9 23.1 49.4 3i.6
41.4 58.0 63.6 59.7 17.3 31.0
15.7 21.1 16.5 14.4 17.5 13.1
.. .
3.1
...
. ..
3.7
...
0.7
4.8
2.7
3.6
...
...
80.9 82.5 82.7 84.9 83.6 88.0
80.2 83.0 81.9 81.1 82.8 83.5
4.1 4.0 4.0 3.9 4.1 3.9
4.2 4.3 4.0 3.5 4.2 4.0
19.7 20.6 20.6 23.0 20.4 22.6
19.1 19.3 20.4 23.2 19.7 20.8
79.5 82.1 78.7 79.4 84.6 84.5
83.5 83.8 83.0 80.4 83.6 84.2
3.9 4.2 4.5 4.6 3.8 3.6
4.4 4.6 4.5 4.3 4.2 4.3
20.1 19.6 17.5 17.3 22.4 23.4
19.0 18.2 18.4 18.7 19 9 19 6
WESTERN C O l L
350
.,
. ..
...
...
,
...
2.6 4.7 3.7
Data presented in Table I11 show very little absorption of hydrogen and virtually no conversion of the coal a t a temperature of 250' C., irrespective of the pressures investigated. Between 300' and 350" C., maximum absorption of hydrogen together with maximum conversion of the coal was obtained. Experiments a t 400' and 450" C. showed diminishing yields. It is the belief of the authors that this last result is due to the fact that active decomposition of the coal has already commenced a t these higher temperatures; consequently, any hydrogenation taking place affects merely the low-temperature distillation products and not the coal itself. These results appear to be entirely in accord with those of the investigators cited. Because of the rapid rise in temperature, the desired point being attained from 30 to 40 minutes after heat was applied, the time of hydrogenation between the limits of 300" and 350' C. was no more than 10 minutes for all experiments where the maximum temperature was above 350" C. Hence it is believed unlikely that any appreciable hydrogenation occurred below the temperatures reported for any experiment. Table IV shows that pressure has little effect upon the yields throughout the range investigated for eastern coal, although the higher pressures appear to give yields slightly higher. For western coal, however, a marked optimum is shown in the vicinity of 211 kg. per square centimeter (3000 pounds per square inch). According to a prediction made by Graham (IO), based on his studies of European coal, the p-bituminous class (Seyler's system) which corresponds to Parr's "eastern bituminous
...
4.3 2.4 2.9
type" should be more readily acted upon by hydrogen than should those of the m-lignitous or "western bitumjnous type." For the two coals investigated, it will be observed that the western coal shows a slightly better conversion. The six best results reported by Graham from a series of twenty-nine samples show between 16.3 and 22.5 per cent residue ( A product). Yields obtained a t optimum conditions for eastern and western American coals, respectively, were 21.1 and 19.3 per cent residue. From these data it appears that the American coals investigated compare favorably with those of Europe with respect to the degree of hydrogenation.
LITERATURE CITED Arend, J. P.,Proc. 2nd Intern. Conf. Bituminous Coal, 2, (1928). Bergius, F., British Patent 18,232 (Aug. 1, 1914). Bergius, F., Proc. 1st Intern. Conf. Bituminous Coal, 102 (1926). Berthelot, M., Bull. SOC. chim., 11, 278 (1869). Fieldner, A. C., Cooper, H. M., and Osgood, F. D., Bur. Mines, Tech. Paper 491, 101 (1931). Fieldner, A. C., Davis, J. D., and Reynolds, D. A,, IND.ESG. CHEM.,22, 1113 (1930). Fischer, F., and Keller, K., Ges. Abhandl. Kenntnis Kohle, 1, 148 (1915-16). Fischer, F., and Schrader, H., Brennstof-Chem., 2, 161, 257 (1922). Fischer, F., and Tropsch, H., Ges. Abhundl. Kenntnis Kohle, 2, 154 (1917). Graham, J. I., Proc. d n d Intern. Conf. Bituminous Coal, 2, 456 (1928). Graham, J. I., and Skinner, D. G., PTOC.3rd Intern. Conf. Bituminous Coal, 2, 17 (1931).
I N D U S T R I A L -4. N D E N G I N E E R I N G C H E M I S T R Y
July, 1932
Kling, A . , and Florentin, D., Proc. 2nd Intern. Con/. B i t u m i n o u s Coal, 2, 523 (1928). Levi, M . G., Padovani, C., and Amati, 8.,C. A , , 22,2261 (1928). Levi, Padovani, and Mariotte, Ann. chim. applicata, 20, 361 (1930j.
Lush, E. J., J. SOC.Chem. I n d . , 48, 112 (1929). Oshima and Tashiro, J . Fuel. SOC.J a p a n , 7, 70 (1!328). Research Council of Alberta (Canada), 11th A n n u a l Rept.,
NO.26,
2 i (1930).
Shatwell, H. G., and Graham. J. I., F u e l , 4, 75 (1025).
751
(19) Shatwell, H. G., and Nash, A. W., Colliery Guardian, 128, 1435 (1924). (20) Skinner. H. G.. and Graham. J. I.. Fuel. 7. 543 (1928). (21) Yancey,' H. F.,'Johnston, K.'A., and Selvig, W. A., Bur. Mines, Tech. Paper 512, 68 (1932). RECEIVED February 17. 1932. Presented before the Division of Gas and Fuel Chemistry a t the S2nd Meeting of the American Chemical Society, Buffalo, N. Y., August 31 to September 4, 1931. C. C. Wright was a du Pant fellow for 1930-31.
The Nitriding of Iron and Its Alloys I. Ammonia Dissociation and Nitrogen Absorption in the Nitriding Process .4.W. COFFMAN,Mellon
I n s t i t u t e of Industrial Research, University of Pittsburgh, Pittsburgh,
Pa.
silica combustion tube. To the end U R I K G t h e past five I n contact with the steels under consideration, of this combustion tube was conyears considerable innected an oil bubbler, the excess ammonia decomposition becomes nearly comterest has been aroused ammonia being absorbed in a water plete at 800" C., while the rate of change of scrubber. A glass T, one arm of in the nitriding process as apwhich was a stopcock, was inserted ammonia concentration with the change of plied in producing very hard and between the quartz tube and oil temperature becomes a maximum at some s o m e w h a t corrosion-resistant bubbler. The gases ammonia, hysurfaces on steel. T h e r e f o r e , drogen, and nitrogen which issued definite temperature coincident with the temperafrom the furnace were sampled .by at the i n c e p t i o n of the studies ture of maximum nitrogen absorption. The means of this stopcock, using r e p o r t e d in t h i s s e r i e s of two glass sampling bulbs filled temperature of this coincidence is dependent on p a p e r s , it a p p e a r e d w o r t h with heavy liquid p e t r o l a t u m the steel. w h i l e to c o n s i d e r quantitasaturated with ammonia. The t e m p e r a t u r e was read by a tively what takes place in the gaseous ammonia phase surrounding steel during the process thermocouple located in a quartz protection tube inside the tube, as shown at 2. The small steel samples of nitrification and to obtain a quantitative indication of the combustion X I/, inch, finished to a smooth commercial grind) (1 x amount of nitrogen absorbed over a range of temperatures. were inserted in the fused silica combustion tube so as to be The present paper describes the research carried out with just a t the end of the thermocouple, thus insuring a coincidence between the temperature of the sample and the indicated temperathese objectives. The decomposition of ammonia accompanied by nitriding ture. action, when reaction takes place between ammonia and steel, The procedure included regulation of the temperature of is considerably more rapid than a decomposition of ammonia the furnace as desired; sweeping the train out with ammonia; b y heat alone or by heat plus a surface such a quartz, glass, regulating the flow until constant at 0.06 cubic foot per hour; glazed porcelain, etc. In this connection it is important to and then, after allowing these conditions to prevail for 30 indicate at the start that true equilibrium is probably never minutes, inserting the weighed samples in the combustion reached in commercial nitriding. The original determination tube and taking gas samples a t intervals through the stopcock. of the ammonia equilibrium was reported by Haber and Van The resultant gas samples were analyzed for ammonia and Ordt ( 2 ) and was followed later by the additional contribu- hydrogen in an Orsat apparatus, removing the ammonia with tions by Haber and his co-workers. Perman and htkinson WATER (4) showed that a t 1100" C. in a porcelain bulb a given d 5CRUBEER FOR dh volume of ammonia gas, under static conditions, was comREMOVAL OF E pletely decomposed in 20 minutes. This fact in itself is evidence that, in nitriding, decomposition is not due to heat effects alone, but also to surface and catalytic effects. Ramsay and Young (5)and also White (7) have shown that ammonia decomposition under conditions of flow through tubes depends to a large extent on the chemical composition of the surfaces with which the ammonia comes in contact, the physical structure of the surface, and its total area. They have shown in To AMMONIA SUPPLY addition that decomposition starts at a little below 500" C. FIGURE 1. D I 4 G R A . M OF APP.4RATUS and is pract(ica1ly complete when iron is present a t or near 800" C.sulfuric acid, and burning the hydrogen b y passing through a copper oxide furnace, the balance being considered as nitrogen. EXPERIMENTAL PROCEDURE I n this manner errors introduced should be found in the balI n determining the percentage decomposition taking place ance. when gaseous ammonia is passed over a sample of steel, the apparatus shown in Figure 1 was employed. AMMONIADECOMPOSITION
D
and an electric furnace of the-Hoskins type, fitted with a fused
active substance such as steel. Consequently, a series of
