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T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
THE ESTIMATION OF PHENOL IN CRUDE CARBOLIC ACID AND IN COAL-TAR OILS By F. W. SEIRROW Received September 5 . 1917
Until quite recently no satisfactory method was t o be found in t h e literature for t h e estimation of phenol in t a r oils or in crude carbolic acid. I n a recent paper, Masse a n d Lerouxl give a method based on preliminary fractionation of t h e crude carbolic acid and subsequent estimation of t h e phenol from determinations of t h e solidifying point. This method suffers from t h e disadvantage t h a t t h e cresols and other higher boiling bodies may vary in t h e fraction containing t h e phenol, while they assume a constant and arbitrary ratio of t h e cresols t o be present. More recently Weiss and Downs2 have published a method in which t h e crude carbolic acid is fractionated in such a way as t o obtain t h e whole of t h e phenol in a fraction supposed t o contain only phenol and t h e cresols, and in this fraction t h e phenol is then estimated by simultaneous determination of t h e specific gravity a n d t h e solidifying point, whence b y reference t o graphs the amount of phenol present is deduced. These graphs also are drawn u p with fixed ratios of meta- a n d para-cresol. I n 1909 t h e author worked out a method for t h e estimation of phenol in coal t a r which depended on quite other properties of t h e constituents for their estimation, and which gave a fair indication of the amount of t h e cresols also present. T h e method gave satisfactory results and was used in t h e author’s laboratory for some years, b u t was not a t t h a t time published. I t is thought t h a t t h e method of attack may not be without interest at t h e present time, and t h e author desires t o t h a n k t h e Directors of Messrs. Hardman and Holden, Ltd., of Manchester, England, for permission t o publish t h e results. I n a paper on t h e determination of phenols in gas liquor,3 t h e author determined t h e “Oxygen Absorption” due t o t h e various constituents of t h e effluent from a sulfate of ammonia works and incidentally of t h e phenol a n d cresols, respectively, in t h a t effluent. This suggested t h e possibility t h a t t h e oxygen absorption might furnish a means t o estimate t h e amount of phenol in a mixture of phenolic bodies. OXYGENABSORPTION OF PHENOLa-. m- AND 0-CRESOL Solutions Required Standard Potassium Permanganate.. 0 . 7 9 g. in 2 liters Standard Sodium Thiosulfate.. . . . . , 7.00 g. crystals in 1 liter Dilute Sulfuric Acid (1 : 3) faintly tinged with Permanganate Potassium Iodide Solution.. , . , , , . , , 10 per cent Starch Solution.. . .. . . . . . . , , , , . . , . , 4 g. in 1 liter
.
.
.
The phenol, etc., was diluted so t h a t 5 0 cc. of t h e solution contained 0 . 0 0 2 g. of t h e particular phenol or cresol. METHOD
Portions ( j o cc.) of t h e permanganate were measured .nto stoppered bottles and 15 cc. of the dilute sulfuric acid added t o each. These bottles were placed in a rack 1
2 8
Comgt. rend., 166 (1916). 361. THISJOURNAL. 9 (1917). 569. J . SOL.Chem. I n d . , January, 1908.
Vol. 9, No.
12
in a thermostat which was maintained a t 23’ C. The solutions of t h e t a r acids were also brought to t h e temperature of t h e thermostat: jo cc. of t h e t a r acid solution were then run into t h e permanganate solution from a pipette also warmed t o 23’ C., a n d t h e time noted when t h e first drop entered t h e permanganate. When t h e whole h a d been added, t h e bottle was quickly shaken tc insure uniformity. At the end of 3 min. t h e action was stopped by quickly adding I cc. of t h e potassium iodide solution. T h e liberated iodine was then titrated with t h e thiosulfate solution. Sufficient excess of permanganate was used so t h a t 30 t o 40 per cent of t h e permanganate remained a t t h e end. The results were then calculated t o grams of oxygen absorbed b y I g. of t h e respective t a r acid. The concordance of t h e results is shown in t h e case of t h e phenol, t h e others being equally good. TABLEI-GRAMS OXYGENABSORBED
Phenol..
. . . . . . . ..
1.435 1 434/Mean 1:434 14.34
o-Cresol.. m-Cresol. $-Cresol
. . . .. ... .....
.... . . . .
1.170 1.156 1.062
O X Y G E N ABSORPTION O F MIXTURES
I n order t o see if any considerable difference would be found in t h e rate of oxidation of phenol if cresols were simultaneously undergoing oxidation, known mixtures mere made up containing varying proportions of phenol t o cresols, t h e cresol taken being a mixture of equal proportions of ortho, meta and p a r a . TABLE 11-OXYGEN ABSORBED
. . .. .
P e r cent Phenol.. . .. . . , OXYGEN Calculated.. ABSORBED: Found.. . Difference.. , , , , . . , , . . .
{ ..
11.1 1.163 1.167 +0.004
25.0 50.0 1.205 1.281 1.212 1 , 2 8 1 4-0.007 0.000
75.0 1.358 1.364
+0.006
88.9 1.400 1.405 $0.005
There appears t o be slightly increased oxidation in most of t h e cases, but this is not sufficient t o cause serious error in t h e use of t h e oxygen absorptions. The rate is naturally dependent on t h e temperature and i t is necessary t o work in a thermostat. Attempts were made t o work with solutions ten times as concentrated as t h e solutions quoled, b u t t h e results were much less steady owing no doubt partly t o t h e considerable temperature disturbance due t o the increased heat of reaction. T h e phenol can thus be estimated with reasonable accuracy provided t h a t t h e ratio of t h e cresols to one another be known, T h e difference in t h e rate of oxidation of t h e three cresols from one another, while much less t h a n t h e difference between the rate of oxidation of any one cresol and t h e rate of oxidation of phenol, is still much too great t o allow of estimation in this way unless t h e ratio of t h e cresols present is known. It is thus necessary t o get some idea as t o t h e ratio of cresols present in order t o proceed. FRACTIONATION E X P E R I M E N T S
It is obvious t h a t in dealing with a mixture of phenol, cresols a n d higher boiling phenolic bodies, which are present in a crude carbolic acid, preliminary fractionation would have t o precede any a t t e m p t a t titration, a n d experiments were carried out in this direction on crude carbolic acid, which was t h e average from a very large amount of t a r from widely differing sources. This crude carbolic acid was fractionated
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T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
through still heads of various types a n d t h e progress of t h e fractionation observed b y taking t h e oxygen absorption of t h e fractions.
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used, being a little t o the advantage of t h e “Pear” form b u t t h a t with t h e Pear a greater volume accumulates in the first fraction which contains t h e largest proportion of phenol. The use of t h e Pear head is OXYGEX ABSORPTION O F HIGHER BOILING BODIES further t o be preferred on account of t h e smaller amount A large sample of higher boiling bodies was obtained of liquid remaining after a distillation. I n all subsewhich had had most of t h e phenol a n d cresols removed quent work t h e Pear form was used. This superiority in a works column still. This was freed from H2S of t h e Pear still head was also established by Weiss a n d was fractionated several times in t h e laboratory and Downs.’ t o remove a n y phenol and cresols which might still It will further be seen by comparing t h e second and remain. Fractions were t h e n collected and their oxyt h e third fractionations, confining our attentions now gen absorption measured with t h e results given in t o t h e values for t h e Pear head only, t h a t t h e “quality” Table I11 of t h e fractions does not alter very materially after TABLEI11 FRACTION , . , ., , .. 205 t o 210” C. 210 t o 215’ C. 215 t o 220’ C. t h e second fractionation, b u t t h a t t h e chief difference Oxygen Absorption.. , . 0.942 0.879 0.831 is in t h e volume of t h e first fraction. From this i t was inferred t h a t more t h a n two fractions would not The oxygen absorption decreases steadily with inbring any commensurate advantage, and t h a t with creasing boiling point a n d wil1 thus throw light on t h e two fractionations a steady state of affairs h a d been progress of t h e fractionation. reached which would be easily reproducible. The COMPARISON O F T H E E F F I C I E K C Y O F STILL HEADS examination of these fractions was then proceeded with, The two still heads giving t h e best results with crude t o ascertain t h e amount of phenol in each. carbolic acid were found t o be t h e “LeBel” bulbs a n d The oxygen absorption of t h e fractions obviously t h e “Pear” bulbs. The Hempel column mas not so gives us no quantitative measure of t h e amount of efficient and h a d the disadvantage t h a t a large amount phenol which they contain as we haT7-e no information of liquid is held u p in t h e glass beads. The Young as t o t h e ratio in which t h e cresols exist in each. dephlegmator. although excellent for lower boiling MAT C H I K G E X P E R I lZIE NT S liquids, did not give as good results in the author’s I n order t o establish definitely t h e percentage of hands as did t h e Pear bulbs. phenol. ortho-, meta- and para-cresol in these fracC O M P A R I S O N O F A 4 - B U L B LEBEL W I T H A 1 2 - B U L B tions, use was made of a fact previously observed by P E A R STILL H E A D - T h e total length of t h e two colt h e author in t h e course of work on the phenols in umns t o the side tube was practically t h e same. I n both cases 1000 cc. of t h e crude carbolic acid was taken gas liquor1 b u t not a t t h a t time alluded t o , uiz.. t h a t if t h e llessinger and 1-ortman method for t h e estimain a copper flask a n d distilled through t h e respective head. An air condenser was used leading into rezeiv- tion of phenol be applied t o solutions of 0 - , In- and ers closed with a calcium chloride tube. Any mois- $-cresol, respectively, t h e end-product obtained (triiodophenol etc.) has widely different colors in each ture was first distilled off and t h e temperature carried t o 180’ C. The phenol was recovered from this, case. The colors of these end-products are extremely dehydrated, and returned t o t h e distilling flask and characteristic a n d may be described as follows: PHENOL 0-CRESOL m-CRESOL p-CRESOL t h e fractionation then proceeded with. The rate of Bright Rose-Pink Brown Slate-Blue D i r t y Yellow distillation was regulated carefully t o one d;op per Preliminary experiments showed t h a t if a known second, a seconds pendulum being placed behind t h e receiver T h e flask was protected by a shield of as- mixture of phenol and t h e cresols be taken, the perbestos paper a n d t h e column enclosed in one thickness centage of each constituent could be determined with of glazed paper t o prevent draughts and t o dirninish good accuracy b y first measuring t h e oxygen absorpsomewhat the radiation from t h e column. Under tion of t h e mixture and then making u p mixtures with these conditions extremely steady conditions were t h e same oxygen absorption, forming the iodo-comeasily maintained. ,4 small Anschutz thermometer pounds, a n d b y t h e method of trial and failure gradually graduated in tenths was used a n d this was compared approaching t h e exact shade of t h e so-called tri-iodowith a standard “N. P. L.” thermometer. compound of t h e mixture t o be analyzed. (The endThe oxygen absorption of each fraction was meas- product in t h e case of t h e cresols is by no means exured and t h e fractions then submitted t o a second actly t h e tri-iodo compounds.) a n d t o a third systematic fractionation. The oxygen The iodo compound was prepared in each case as absorption of t h e fractions of t h e second and of t h e follows: 2 0 0 cc. of water and 3 . j cc. N NaOH were third fractionations were also measured. Table IV mixed; I g. of t h e t a r acid was dissolved in 500 cc. contains t h e results so obtained. The two first tem- of water and 2 5 cc. of this solution were added t o t h e perature intervals in t h e first fractionation are differ- dilute sodium hydroxide solution. This was heated ent from those in t h e second and third fractionations, t o 70’ C. in a stoppered flask and 2 5 cc. of 0 . 0 2 N b u t in all subsequent work t h e latter intervals were iodine solution added and well shaken. After standused. ing for j mins. t h e flask was cooled under the t a p , If we examine these fractionations we see t h a t t h e t h e mixture slightly acidified with sulfuric acid a n d t h e oxygen absorption of t h e fractions is much t h e same excess of iodine removed with a slight excess of sodium whether t h e “Pear” or t h e “LeBel” column is 1 L O C . cit.
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
I 104
TABLEIV-COMPARISON
FIRST F R A ?CIONATION ~
BULB PEAR 4-BULB LEBEL Vol.
Temperature
CC.
202 205
to205 to208
57 35
0 Abs. 1.293 1.305 1.257 1.204 1.159 1.117 1.074 1.037 1.003
VOl. 0 Cc. Abs. 27 1.292 112 1.300 243 1.266 130 1.214 81 1.166 62 1.125 69 1.079 51 1.036 31 0.999
SECOND FRACTIONATION
~Z-BULB PEAR BULB Temperature Vol. 0 Vol. No. C. Cc. Abs. Cc. 1 180to184 143 1.342 124 2 184to187 179 1.293 174 3 187 t o 1 9 0 75 1.233 114 79 4 190to193 78 1.188 5 193 t o 1 9 6 65 1.133 66.5 6 196to199 661.098 69 7 199to202 61 1.068 54 8 202 t o 2 0 5 44 62 1.028 9 205to208 23 23 0.972
TABLEV-RESULTS OF MATCHINGEXPERIMENTS 1-SECONDFRACTIONATION 2-THIRD FRACTIONATION -PERCENTAGE* -PERCENTAGESVol. Phe-Cresol0 Vol. Phe--CresolN ~ cC. . nol Abs. cC. nol $ 1 143 71.0 1 4 . 8 14.2 o 1.117 202 73.5 1 4 , s 12.0 0 0 1.114 100 5 7 . 1 21.4 21.4 0 2 179 56.0 20.8 2 3 . 2 3 75 40.5 18.7 4 0 . 8 o 1.096 87 40.5 25.5 34.0 o 0 1.083 56 25.0 25.0 50.0 0 4 78 3 0 . 0 22.2 47.8 5 65 15.9 18.7 6 5 . 4 o 1.076 53 1 5 . 4 21.1 63.5 o 6 66 6.9 18.6 65.7 8 . 8 1.073 85 3 . 2 19.8 68 5 9.0 7 61 o 1 1 . 3 72.8 15.9 1.068 70 o 1 1 . 3 72.8 15.9
* ,,,
The. mixtures were made UP t o have t h e Same OXYgen absorptions as t h e respective fractions with t h e exception of t h e higher fractions-where it was found t h a t better matches could be obtained b y making mixtures with slightly higher oxygen absorptions t h a n t h e fractions. This was probably due t o t h e small amounts of higher boiling bodies in the higher frattions. ( T h e color of t h e “iodo-compounds” of the higher boiling bodies is not pronounced, while their oxygen absorptions are progressively less t h a n the cresols.) Table V gives t h e results of these matching experiments. T h e last column gives t h e mean oxygen absorption of everything except phenol in t h e fractions, calculated from t h e oxygen absorption of t h e fraction, t h e oxygen absorption of pure phenol and the found percentage of phenol in t h e fraction. Here we see more definitely t h a t t h e percentage of phenol TABLE VI-RESULTS
c.
No. 1 2 3 4 5
180to184 184to187 187 t o 1 9 0 190to193 193 t o 1 9 6 196to199 199to202
6 7
PERCENTAGES IN: No.
1. AMOUNTOF FRACTION-A B C Cc. G. G. 377.3 143 41.6 152.1 173.8 179 68.7 75 200.6 45.1 78 115.5 37.7 65 109.6 23.5 66 104.2 22.6 61 106.1
FRACTIONS FROM B -Cresolo p m
Pheno1
D G. 7.4 58.3 171.2 151.1 128.3 125.5 147.4
LEBEL 0 Abs. 1.337 1.299 1.236 1.189 1.139 1.099 1.060 1.022 0.978
(3)-TAIRD FRACTIONATION 12-Bm~ PEARBULB LBBEL Temgerature Vol. 0 Vol. 0 No. C. Cc. Abs. Cc. Abs. 1 180to184 202 1.351 165 1.340 2 1 8 4 t o 187 100 1.297 126 1.297 1.236 lS7 to190 87 1.240 4 190to193 56 1.183 64 1.185 1.137 1.094 7 199to202 71 1.060 71 1.058
~~~~~i~~
z!
in the third fractionation has not changed very m a terially from t h a t in t h e second fractionation. RESULTS OBTAINED WITH OTHER MATERIALS
7 T h e preceding results were obtained with a large stock sample of crude carbolic acid representing t h e total extract from a very large a m o u n t of tar. Similar experiments were then carried out with other materials as follows: A-For
comparison:
Material already quoted
zi
R $ ~ , ~ d ~ ~ ~ $ ~ f i ~ D-Another sample of Refined Cresylic Acid of different origin E-Another sample of Crude Carbolic Acid of different origin t o t h a t quoted in “A”
~~~~~~~~
These were submitted t o preliminary purification t o free t h e m from HsS, etc., a n d were then fractionated twice in t h e manner described. I n A t h e Volume of t h e fractions was measured; in all subsequent operations t h e fractions were weighed t o t h e nearest decigram. Results are given in Table VI. I n Table VI1 is given t h e mean oxygen absorption of everything except t h e phenol in the fractions, calculated as before indicated from t h e oxygen absorption of t h e fraction, the oxygen absorption of Pure Phenol a n d t h e found percentage of phenol in t h e fraction. From these data we see t h a t the mean oxygen absorPtion of the cresols, etc., in t h e fractions is Very cons t a n t for one a n d t h e same fraction and Varies very little with the nature of t h e material distilled. T h u s . i t seems evident t h a t t h e larger variation Of t h e OXYgen absorption of t h e fractions themselves is caused Principally b y variation in t h e Percentage of Phenol PresentM E T H O D O F ANALYSIS A D O P T E D
Thus t h e method adopted for the analysis of a n y unknown sample of crude carbolic acid was t o fractionate about a liter of t h e sample in t h e manner outlined and then determine t h e oxygen absorptions Of t h e fractions of the second fractionation. T h e per-
WITH
VARIOUSMATERIALS
E
G. 44.9 183.0 104.3 76.0 70.1 56.9 63.7
-2. No. 1 2 3
4 5
6 7
A 1.342 1.293 1.233 1.188 1.133 1.098 1.068
OXYGENABSORPTIOND B C 1.272(a) 1.355 1.332 1.287 1.297 1.294 1.245 1.238 1.235 1.195 1.172 1.175 1.132 1.130 1.147 1.099 1.087 1.103 1.065 1.070 1.071
3. MATCHING FRACTIONS FROM D FRACTIONS FROM EXPERIMENTS C Phe-CresolPhe-Cresols-no1 o p m no1 o 9 m 50.0(a)22.2 27.8 0 12.0 0 54.2 21.5 24.3 0 575.0 7.3 213.0 0.1 22.6 0 44.0 23.3 32.7 0 40.9 17.5 41.6 0 31.0 28.1 40.9 0 26.7 18.2 55.1 0 1 8 . 1 2 3 . 1 51.9 6.9 15.0 26.7 33.3) 251 9.4 17.5 61.8 11.3 4.7 19.2 57.3 18.8
E 1.327 1.302 1.251 1.207 1.150 1.101 1.066
FRACTIONS FROM E o-Cresol- P m
Pheno1
66.5 16.1 17.5 15.0 0 58.6 20.3 56 7 5 .. 56 23.1 21.3 0 4 5 . 4 18.7 b ZM°CS 3 40.5 18.7 40.8 0 35.5 23.3 26.7 18.2 55.1 0 20.6 14.1 15.2 17.6 6 1 . 4 5 .8 :la* 10.6 21.2 5.8 17.1 60.5 16.6 k.: J 0 9 62 29 (a) O n thelfirst fractionation the volume of t h e first fraction was so small t h a t i t could be distilled only through a 3-bulb Pear-head.
3g P
1
:
12
OF 4-BULB LEBEL WITH A ~ Z - B U L B PEAR STILL HEAD
thiosulfate solution. T h e precipitated iodo compound was allowed t o settle, washed once by decantation a n d placed in a small clear glass weighing bottle for comparison. It is essential t h a t the compound be freshly prepared as it becomes lighter in color after standing one or two hours. T h e method is clearly cumbersome but it was used only t o establish the percentages present in the fractions once a n d for all, i. e., as a method of standardization. I n this way the percentages of phenol, 0 - , m-,a n d p-cresol were determined in t h e fractions through t h e Pear still head for t h e second a n d third fractionations quoted in Table IV, ( 2 ) a n d (3)
Temp.
Vol. 9 , No.
................
................
17.4 21.1 35.9 41.2 61.9 59.9
0
0 0
0
3.4
. . . . . . . . . . . . .8.3 ..
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T E E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
TABLEVII-MEAN
No.
................. .................. .................. ................. ................ ..................
1. 2 3 4. 5.. 6
’
OXYGEN ABSORPTIGN OF THE CRESOLS, A B C D E 1.117 1 . 1 2 0 1 . 1 1 8 (1.110) 1 . 1 1 4 1.114 1.119 1.113 1.115 1.113 1 . 0 9 6 1.099 1 . 1 0 2 1.097 1,099 1 . 0 8 3 1 . 0 8 1 1.077 1.082 1.088 1,076 1.076 1.078 1.076 1.084 1.073 1.078 1.070 1.069 1.062
ETC. Mean 1.117 1.115 1.099 1.082 1.078 1.070
centage of phenol in each fraction was then calculated from t h e oxygen absorption of pure phenol and the oxygen absorption of t h e cresol, etc., in t h a t fraction as given in Table V I I . I n Table VI11 comparison is made of t h e percentages of phenol found in the materials A , E , C, D a n d E ( I ) By direct matching of the fractions. ( 2 ) By calculation, as described, from t h e mean oxygen absorptions of t h e cresols, etc., in t h e respective fraction. These results are not, of course, independent, as t h e results in t h e second case also depend on t h e matching experiments, b u t t h e result indicates how far t h e mean oxygen absorption of t h e cresols, etc., in t h e fractions may be regarded as fixed points, thus avoiding t h e necessity for t h e tedious matching experiments i n each case dealt with. TABLE VIII-PERCENTAGESPHENOL Material A B
......................... ......................... c ......................... D ......................... E .........................
B y Direct Matching 30.0 27.7 44.0 20.5 24.6
BY Calculation 30.0 28.0 43.9 20.7 24.5
SOURCES OF ERROR I N THE PRECEDING WORK
I-It
has been noted t h a t in t h e case of t h e higher boili.ng fractions better matches were obtained when mixtures were made u p having slightly higher oxygen absorption t h a n t h e fractions t o be matched, and i t was pointed out t h a t this was probably due t o increasing amounts of higher boiling bodies in these fractions. It would undoubtedly have been better t o have taken some of this higher boiling material as well as phenol a n d t h e cresols in t h e matching experiments. 2-It was found after t h e method had been in use for some time t h a t in practically all experiments with crudes a disturbing factor was present in t h e form of small amounts of pyridine. 3-It was further observed t h a t crude carbolic acid tenaciously retains small amounts of dissolved sodium phenate when water is also present. Thus water is much more soluble in crude-tar acids in presence of sodium phenate, and, on t h e other hand, sodium phenate is considerably soluble in t a r acids i n presence of water. This sodium phenate remains in t h e distilling flask when t h e mixture is distilled. It was found necessary t o treat t h e crude carbolic acid with successive washes of dilute sulfuric acid, followed b y washes of water t o remove pyridine a n d decompose t h e dissolved sodium phenate. T h e t a r acids in t h e acid a n d water washes were recovered a n d returned t o t h e bulk. When these disturbing factors were discovered, time was not available t o repeat t h e work herein recorded, b u t t h e effects were partially eliminated b y using t h e constants already determined on a series of synthetic mixtures with“known amounts of phenol
1105
and varying and known amounts of t h e cresols a n d higher boiling bodies. I n t h a t way a correction was found t o be applied t o all results as so obtained. T h e resulting corrections when plotted against the percentage of phenol found gave a smooth curve. Typical points from this curve are given in Table IX. TABLEI X
............. ............ ...............
Per cent Phenol Taken.. Found.. Correction (per cent).
10.00 25.00 50.00 9 . 6 2 23.98 47.50 1.02 0.38 2.50
75.00 70.54 4.46
Duplicate determinations when carried out with t h e precautions mentioned on t h e same sample of material gave results with a maximum variation of not more t h a n about 0 . 2 t o 0 . 3 per cent and with t h e above corrections applied were not very much farther t h a n t h a t from t h e t r u t h . OXYGEN ABSORPTION OF THE FRACTIONS OF TAR ACIDS PROM VARIOUS KINDS OF TAR
T h e method was also used t o estimate t h e phenol in the t a r acids from inclined retorts, vertical retorts, blast furnace creosote and producer gas tar. I n Table X are quoted t h e oxygen absorption of t h e fractions of t h e second fractionation of these materials. T h e first column contains results already given which were largely for t h e material from horizontal retorts. With the exception of t h e first column t h e t a r acids received t h e preliminary treatment with dilute sulfuric acid, and were further carefully freed from a n y neutral oils b y conversion t o phenate and extraction with benzene, with all necessary precautions t o recover a n y phenol which was so washed out. It will be seen t h a t these oxygen absorptions all lie in much t h e same range. No.
TABLEX-OXYGEN ABSORPTION OF FRACTIONS Horizontal Inclined Vertical Blast Producer 1.342 (1.288) 1.293 (1 2563 1.293 (1: iis) (1: i i 7 ) 1.244 1.243 1.233 1,202 1,201 1.175 1.195 1.188 1.155 1.152 1.123 1.128 1.133 1,102 1.105 1.095 1.101 1.098
................. ................. ................. ................ ................ 6 ................. 1 2 3 4. 5.
:
..
The figures given in parentheses were for very small fractions which could not be handled through t h e 1 2 bulbs. REMARKS
It will be noted from t h e matching experiments t h a t t h e fraction from 199 t o 2 0 2 ’ always contains definite a n d easily detectable percentages of phenol, b u t t h a t in t h e fraction above 2 0 2 ’ no phenol was ever detected. Weiss a n d Downs also distilled twice, b u t collected only two fractions, v i z . , “to 190’” a n d “190 t o 2 0 2 ’ ” on t h e first fractionation, while on t h e second they collected everything up t o 197’. It seems certain t h a t under these conditions some phenol must have been left in t h e distilling flask, while some of t h e higher boiling bodies must have inevitably appeared in t h e distillate. Another point which is of interest in connection with t h e work of Weiss a n d Downs is t o be found in t h e amount of rn-cresol present I n t h e materials investigated b y t h e author the amount of m-cresol in t h e fractions up t o 2 0 2 ’ was invariably far less t h a n t h e amount of o-cresol or of $-cresol. Thus from t h e figures in Tables IV, V a n d VI1 t h e following
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T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
ratios may be calculated for the materials designated "A,,, ((B"and (IC.>> A-o:p:m = 6.5:12.8.. B-o:p:m = 6.0:13.0:1 C-o:p:m = 8.3:11.5:1 AS meta-cresol boils only 3" higher t h a n p-cresol, it seems certain t h a t in t h e original materials dealt with t h e amount of p-cresol must much exceed t h e amount of m-cresol. Weiss a n d Downs in t h e preparation of their graphs made u p synthetic mixtures in which t h e ratio of para t o meta was fixed a t about I : I and they s t a t e t h a t t h a t is t h e approximate ratio in which they exist in their oils. The question arises whether their method would give reliable results when applied t o t h e t a r acids dealt with b y t h e author. I n t h e present method such variation in t h e ratios of t h e cresols present would be eliminated, a t a n y rate t o a considerable extent, although t h e ratio of cresols worked with in t h e preparations of t h e synthetic mixtures was not varied as far as t o include a ratio, m : p = I : I , so t h a t definite figures cannot be given. It would be interesting t o follow up this a n d t h e other points raised a t greater length b u t t h e author has not now access t o t h e necessary crude materials. CHEXICAL DEPARTMENT, MCGILLUNIVERSITY MONTREAL. CANADA
ANALYTICAL CONTROL OF THE AMMONIA OXIDATION PROCESS BY GUY B. TAYLOR A N D Jos. D. DAVIS Received October 17, 1917
I n t h e manufacture of nitric acid from ammonia, a mixture of air a n d ammonia gas is passed over a suitable catalytic material heated t o temperatures above red heat. Two reactions occur: 4 NH3+5 oz=4 N 0 + 6 HzO (1) 4 NH3+3 0 2 = 2 N2+6 H20 (2) It has been suggested t h a t reaction ( 2 ) may come about by means of t h e intermediate reaction,* 4 NH3+6 N O = j N2+6 H20. (3) I n testing out a particular t y p e of commercial oxidizer, t h e authors believe they have found evidence t h a t under certain conditions this reaction does occur. T h e oxidizer in question was so constructed t h a t the burned gases remained hot f o r Some time' Further' there was irregular local cooling of t h e catalyst due t o eddy currents in t h e burned gases. Consequently, there must have been considerable ammonia passing such points unburned. I n fact, analysis of samples taken from points near t h e cold spots showed ammonia while in samples taken outside the catalyst chamber t h e ammonia content was very low. T h e authors believe t h a t most of t h e NH, passing through t h e cold spots was subsequently "burnedj, b y the hot NO. ~~~~l~~ with this apparatus were uniformly about I O per cent lower t h a n those obtained with t h e same lot of catalytic material in a differently constructed oxidizer. The nitric oxide is converted into nitric acid b y passing t h e gases through suitable absorption towers, 1 2
Published by permission of Director of U.S. Bureau of Mines. Reinders and Cats, Chem. Weekblad, 9 (1912), 47-58.
Vol. 9, No.
12
much t h e same as in t h e arc process of direct fixation of atmospheric nitrogen. T h e efficiency of a n ammonia converter depends upon establishing conditions favorable t o reaction (I) a n d suppressing as far as possible reaction ( 2 ) . If t h e ultimate product desired is nitric acid, little or no free ammonia should be allowed t o pass t h e converter unchanged. I n order t o test t h e efficiency of conversion, analyses of t h e entering ammonia-air mixture and t h e exit nitrose gases must be made. The former offers no special difficulties b u t t h e nature of t h e acid gas creates a special problem. As soon as t h e gas sample cools, t h e nitric oxide begins t o react with t h e excess oxygen present t o form NOz, which partially dissolves in t h e condensed water, so t h a t t h e gas taken into a n y sampling device consists of a mixture of nitrogen, oxygen, and nitrogen oxides of indeterminate molecular species. The principle upon which t h e efficiency calculation is based is as follows: t h e ratio of t h e nitrogen combined as ammonia t o total nitrogen in t h e intake gas is equal t o t h e ratio of t h e nitrogen derived from t h e ammonia t o total nitrogen in t h e exit gas. Let a =nitrogen combined as N H 3 in t h e air-ammonia b =free nitrogen sample and c =nitrogen combined as nitrogen oxides in t h e d = free nitrogen } exit gas f = nitrogen combined as ammonia escap) sample ing oxidation T h e nitrogen in each sample must of course be expressed in terms of the same unit. Then
,
(3)
where x is t h e free nitrogen derived from t h e reaction expressed by Equation ( 2 ) . The efficiency is then expressed by t h e relation -C- - Yield
c + f + x or, substituting t h e value of x from (3), a(c
b, +d+ I,X
IOO
= Per cent Yield.
(4)
(j)
EXPERIMENTAL METHODS
I n t h e course of some experiments on ammonia oxidation, several methods of procedure were developed: M E T H O D I-The apparatus is sketched in Fig. I. Air and was passed through the meter A , the water pressure gauge B , and t h e bottles c containing ammonia liquor ( 7 per cent "3). The ammoniaair mixture passed over t h e catalyzer in D a n d t h e acid gases Out through E' The tubes H H',capacity about 1 2 0 0 cc., were filled with water. K contained 2 0 cc. N / s and K" '5 cc* N / 2 NaoH plus 3 cc. Of 3 per cent hydrogen peroxide' The ammonia-air sample was drawn through K b y allowing a measured volume of water t o flow from H . Before drawing t h e acid sample t h e air in K" was displaced b y pure oxygen passing in at G and out at F. T h e two samples were then drawn simultaneously SO
''
I
