Hydrogenation of American Coals in Diphenyl m'. L. BEUSCHLEIN, C. C. WRIGHT,AND C. M. WILLIAMS Department of Chemical Engineering, University of Washington, Seattle
This work shows that the effect of the dispersion other than t h e n a t u r a l c o a l American coals in a staagent upon the of coal hydrogenation is speash was employed. After r e nioval of air by hydrogen flushtionary r e t o r t using cific. The commercial treatment of a coal can be ing, the r e t o r t was charged phenol (a) and anthracene (5) RS d i s p e r s i o n media has been expected to be intimately dependent upon fhe with h y d r o g e n t o a pressure dispersion agent and the process treatment of of 141 kg. per sq. cm. a t room reported by this l a b o r a t o r y . products. Repeated hydrogenation with anthratemperature, and then heated This work has been extended to a t 350' c. for 8 hours. During cene and eztractio,z with benzene of Wilkesoncoal include diphenyl as the disperthe experiments, pressures of and Of the is shown to be an eflective method for dissolving approximately 317 kg. per sq. previous experiments have been repeated using a r o t a t i n g lhe cm. were attained, and, upon bomb with stirrer. Some comc o o l i n g to r o o m temperature, parative methods for examination of the products resulting the final pressure was always lower than the initial. Pressure from the hydrogen treatment have been included. readings taken during runs were often unreliable owing to clogging of the gage tubing with solid diphenyl. This same EXPERIMENTAL METHOD trouble often prevented the determination of the volume of The hydrogenation apparatus with the stationary retort gases left in the bomb after an experiment. has been described ( I , 2). For the purpose of stirring the Of the twelve coals treated, each product upon removal coal charge during the treatment, the retort was placed in a from the bomb appeared as a gray mass of crystals and tarry horizontal position upon a set of rollers which were rotated matter. Water separated out in amounts varying from 0.1 slowly by means of a small motor with appropriate reduction to 5.0 grams, depending upon the coal treated. The larger gearing. The inner cylinder used with the stationary retort quantities were found on treating sub-bituminous coals high for holding the coal sample was discarded during rotary in oxygen. The solid and liquid products from the bomb were operation and replaced by a short length of chain loosely extracted with benzene in a Soxhlet extractor, and the inspread along the bomb by a stout copper rod. As the appa- soluble residue was subsequently carbonized a t 550" C. in a ratus rotated, the chain rolled and scraped along the bomb Fischer retort without steam. The benzene-soluble portion wall and insured thorough mixing. The spacer rod was and the tar obtained from the carbonization were combined, effective in retaining the chain throughout the length of the and the total weight, corrected for diphenyl, is reported as bomb. Only constant volume experiments were possible as total tar. The results are presented in Table I. Since tars the hydrogen storage cylinders had to be disconnected during form one of the valuable products when coal is distilled comrotation of the retort. mercially, the low-temDerature carbonization of hvdrogenated residues was intended to throw some light u p o i the-tar TREATMENT WITH DIPHENYL yields of treated and untreated coals. A %gram sample of coal (-60 mesh), together with 20 For comparative purposes, three coals were hydrogenated grams of diphenyl, was placed in the retort. No catalyst with anthracene substituted for diphenyl. The analytical
T
HE hydrogenation of some
I
TABLEI.
BENZENE EXTRhCTION
a b
DISTILLATION OF HYDROGENATED COALS~
AND
DIPHENYL
Dispersion medium:
-ANTHRACEND---.
FIXED rARBOS
EXTRACTED TAR
Tar
Coke
EXTR.4CTED TAR
Tar
Coke
%
%
%
%
%
%
%
63.3 63.7 59.9 57.9
25.6 24.0 42.6
1.8 1.8 1.5
61.5
19,:
;3 6
65:9
14.2 47.5 13.8 39.0 46.4 12.5 15.6 32.7
6.7 2.2 5.9 3.0 1.5
51.1 41.6
37 2
2.5
53.2 49.7
17 5
3.6
COAL,^ B ~ DAND , STATE Fairfax 5 Wash Wilkesdn '7 Wash. Flat Top' diary Lee Ala. Boone 2 'Chilton W. Va. 204, Elkhorn, K ;. Orient 1 Illinois 6 Ill. Occidenlal 2 Wadh, Rolapp C A d e Gate Utah Roslyn '7, Roslyn, Wash. New Black Diamond, Jones, Wash Tono, 1, Wash. Ford's Prairie, Foron, Wash Ail results re orted on ash- and moisture-free basis. A complete &scription of the coals has been reported
59.0
47.7 46.9 49.1 43.5 44.4
39.3 30.8
50.1
DISTILLATION
58.1 41.2 44.7 62.4 46.6
2.8
25.8
1.7 2.7 2.4
DIBTILLATION
. .
...
29.5
in a previous paper ( 8 )
TABLE 11. PHENOLEXTRACTION OF HYDROGENATED C04LS' Dispersion medium' Products.
-.kNTHR4CENI-
A
B
%
%
COAL Wilkeson Wash. 2.1 Flat Top' Ala. 10.9 Occident& Wash. 8.1 New Blsok Diamond Wash. 2.9 Ford's Prairie, Wash.' 2.9 All results reported on ash- and moisture-free basis.
94.0 72.1 63.1
53.7
35.4
C %
*-
--DIPAE\TYL--
-PHENOL--
c
A
B
4
%
%
%
B %
%
18.2
25.5
iP.8
1.4
69.3
34.0
21.3 11.1 23.2
1316
64:6
..
26.4 32.1 ..
44:2
,.
2 7 2.2
18.7
465
,
..
..
. .
31.2
..
466
INDUSTRIAL AND ENGINEERING
procedure was the same as for the diphenyl, and the results have been included in Table I, together with those previously reported for anthracene using the stationary retort (3). The results presented in Table I for experiments using diphenyl show little correlation between the yield of tar and the original composition of the coal stated as percentage of carbon, fixed carbon, or ratios of carbon to hydrogen, carbon to net hydrogen, etc. I n several instances the conversions to tar are similar to those previously reported for the same coals using anthracene as the dispersion medium in a stationary retort. However, for the three coals investigated, there appears to be no apparent agreement between the conversions obtained with anthracene as the dispersion agent in the rotating retort and those obtained with the same medium in the stationary retort. It was thought that stirring should increase the ease of hydrogen absorption, in particular, if some equilibrium n'ere to exist between soluble products formed and diffusion of them into the dispersion medium.
EFFECTOF DISPERSIONMEDIA As a further comparison of dispersion media, two coals were hydrogenated with diphenyl, three with phenol, and five with anthracene. The method of Shatwell and Graham (4) for the analysis of the products was followed whereby they were separated into three parts: A, insoluble in phenol; B, soluble in phenol and insoluble in chloroform; and C, soluble in phenol and chloroform. The apparatus and procedure for the hydrogenation were those used in the previous diphenyl experiments except where phenol was the dispersion agent, and then the weight ratio of coal to phenol was 1:l. The results appear in Table 11. Three of the five coals dispersed in anthracene and all of those in phenol were rendered almost completely soluble in phenol, the residues being less than 3 per cent. From the limited data available, these two agents appear to be much more effective than diphenyl. The yield of B product was largest for the high-carbon coals, decreasing with the carbon content; this indicated that those coals most deficient in hydrogen were the least easily converted into the C product which is a liquid tar. Experiments on the conversion of B products to C products might show some valuable properties of various solvents. The tar acids and bases can be indicated by the losses occurring in the washings of the phenol-soluble extracts (B and C products) with dilute sodium hydroxide solution. It was found that, regardless of the dispersion medium, these tar acids and bases in the products vere Iess with high-carbon coals than with those of lower carbon content. The chloroform-soluble fraction corresponds in physical characteristics to the benzene-soluble portion obtained in the coking runs. The amount of tar appears to be about the same, irrespective of rank of coal. It would rather appear from the data that the fractions of the low-rank coal which produce tar acids and bases have been metamorphosed in the higher ranks so that they produce the B products upon hydrogenation. REPEATED HYDROGENATION AND EXTRACTION The use of the benzene extraction method upon hydrogenated residues has obvious advantages when tarry products are desired. Wilkeson coal mas extracted with benzene and was found to have a negligible solubility. A fresh sample with anthracene was then hydrogenated, and the products were extracted with benzene. A portion of the insoluble material was carbonized, and the remainder was returned to the retort with more anthracene and retreated with hydrogen. This procedure was repeated a third time, the product being extracted and a portion carbonized. The results are described in Table I11 and show that removal of the benzenesoluble portion and the addition of anthracene allow hydro-
CHEMISTRY
Vol. 26, No. 4
genation to proceed. Whereas the single treatment shows a yield of 19.7 per cent tar, two additional treatments increase this to 54 per cent. This indicates that the coal could be rendered essentially benzene-soluble by successive treatments. Apparently, extraction during hydrogenation would be advantageous for effecting solution of the coal. TABLE111. EFFECTOF REPEATED BENZENEEXTRACTION OF HYDROGENATED COAL^ (Wilkeson, Wash , coal dispersed in anthracene) EXTRACTION CARBONIZATION OF BENZENE Solid Soluble SOLIDRESIDUE residue tar Coke Tar
%
%
...
%
Raw coal 99.5 80.9 1st treatment 80.0 19.7 65.9 2nd treatment 59.5 16.3 47.0 3rd treatment 35 9 17.9 29.6 Final yield 35.9 53.9 29.6 a All results on ash- and moisture-free basis of original b Nitrogen used in place of hydrogen.
TOTAL TAR
%
%
3.5 1.1 2.3
10.1b 23.2 17.4 20.2
...
...
coal
COMPARlSON O F TREATMENTS I n Table IV are shown the results obtained by treating New Black Diamond coal with hydrogen under various conditions of time, pressure, and dispersion medium. It is evident that initial pressures of 140 kg. per sq. cm. a t room temperature are advantageous for converting the coal into phenol-soluble products. That the dispersion medium plays an important part is indicated by the small decrease in phenol solubility obtained when no medium is used as compared with those for anthracene and phenol. TABLEIV. VARIOUSTREATMENTS OF NEW BLACK DIAMOND, WASH., COAL4 DISPERSION MEDIUM
INITIAL PRESSURE HYDRO-
OF
OEN
-
TINEO F HYDROQENATION
AT35O0C* Hours 8 8
--PRODUCTSCoke
%
Total
%
Tar A %
Tar B
%
Tar
C
%
Ka./so. cm. - , 73.2 5.7 Anthracenea 141b .. .. 38.0 28.8 141 , . .. Anthracenec 51.9 2 1 . 1 Anthracene 14 1 8 .. .. 53.2 1 4 . 2 141 8 Diphenyl Extracted only .. 88:O 0:9 0:4 Noned 8 38.7 .. 68.5 8.9 Diphenyl 38.7 54 .. 33.7 Diphenyl 141 8 .. ,. Anthracene 2 . 9 53:7 ii:i 127 8 .. .. 62.7 13.8 6 . 1 None 38.1 4 5 4 . 0 21.7 .. 7.5 Phenol 8 38.1 .. 43.3 Phenol 141 8 .. . . 2.2 3211 3 i : 2 Phenol 49.9 1 3 . 2 12.8 141 8 Phenold a All results reported on ash- and moisture-free basis. a Hydrogen replaced by nitrogen. C Experiments without stirring reported in a revious paper (3). d Experiments reported in a previous paper &).
... .
..
..
.. ..
..
.. ..
..
..
The effect of the ash in the original coal upon hydrogenation has not been investigated in any of the experiments reported in this paper. I n those runs showing less than 3 per cent residue insoluble in phenol, some of the ash passed through the extraction thimble with the hot phenol and appeared in the B products. ACKNOWLEDQMENT The authors are indebted to the United States Bureau of h?ines for the samples of coal used in these experiments. The investigation was made possible b y a Grant-in-Aid of the National Research Council to W.L. Beuschlein. LITERATURE CITED (1) Beuschlein, W. L., Christensen, B., and W r i g h t , C. C., Univ. W a s h i n g t o n Eng. Expt. Sta., Bull. 69 ( J a n . 2, 1933). (2) Beuschlein, W.L., and W r i g h t , C. C., IND. EKQ.CHEM.,24, 1010 119.12. - ~ \--
,
(3) Ibid., 25, 409 (1933). (4) Shatwell, H. G., and Graham, J. I., Fuel, 4, 75 (1926). RECEIVEDSeptember 20, 1933. Presented before the Division of Gas and Fuel Chemistry at the 86th Meeting of the American Chemical Society, Chicago, Ill., September 10 t o 15, 1933.
