January, 1934
I N D U S T R I A L AIVD E N G I N E E R I N G C H E M I S T R Y
the mixture becomes homogeneous. Gilsonite and fatty acid pitch, alone or mixed with resins or vegetable drying oils or both, may also be used satisfactorily. The pigment will vary in quantity from one-half to the same weight as the bituminous base, depending upon the intensity of the pigment, the opacity of the base, and the color of the paint desired. McRae (14) has patented a mixture of gilsonite, Trinidad asphalt, solvent, and pigment for this purpose. Colored bituminous emulsion paints are likewise being used successfully. Pigmented bituminous compositions have found a use as antifouling paints. They protect the bottoms of metal ships against the growth of barnacles as well as against the corrosive action of sea water. Copper and mercury compounds are often used for their toxic properties. Bowles (3)has described as satisfactory a composition consisting of asphalt, fatty acid pitch, and linseed oil in solution in tar oil, together with red iron oxide and a toxic compound. These are prepared by grinding BITUhfINous ENAMELS. dry pigments into bituminous varnishes. With most pigments comparatively dark hues are obtained. The recently developed asphalt-aluminum enamel gives a bright, lustrous film. Bituminous enamels possess the advantages of extreme durability and low cost. Bituminous materials are less expensive than the resins otherwise used and are also more weather-resistant. The bituminous varnish employed as a base is made as translucent as possible in order to bring out the color of the pigment. Bituminous substances having a brown streak are selected and combined with a substantial amount of resins and oils. A distinguishing characteristic of bituminous varnishes is that hardening of the film takes place
91
by oxidation of the vegetable drying oil. Gilsonite is used most frequently, since it shows the optimum brown color, possesses the necessary hardness, and does not cause livering with lead, zinc, and chromium pigments. BITUMISOUSCELLULOSE-ESTER LACQUERS.These lacquers, prepared by mixing together a solution of bituminous substances with a solution of cellulose ester, are sometimes colored by the addition of various pigments. Lacquers containing 25 to 30 per cent by weight of pigment dry quite rapidly to a semi-glossy coating and possess considerable toughness. They withstand atmospheric exposure very well. LITERATURE CITED (1) Abraham, H., “Asphalts and Allied Substances,” 3rd ed., Van Xostrand, 1929. (2) Abraham, H., U. S. Patent 824,898 (July 3. 1906). (3) Bowles, P. E., J . SOC.Chem. I n d . , 41, 492R (1922). (4) Bur. of Standards, Letter Circ. 42, revised (Feb. 12, 1923). (5) Edwards, J. D., “Aluminum Bronze Powder and Aluminum Paint,” Chemical Catalog, 1927. (6) Fleming, C. S., U. S. P a t e n t 1,568,215 (Jan. 5, 1926). (7) Goodwin, H., and Smith, H., British P a t e n t 212,188 (March 6, 1924). (8) Hannam, G. C., and Sohede, J. W., U. 5. Patent 1,637,301 (July 26, 1927). (9) Ibid., 1,637,302 (July 26, 1927). (10) Kirsohbraun, L., Ibid., 1,417,839 (May 30, 1922). (11) Ibid., 1,528,436 (March 3, 1925). (12) Lukens, A. R., U. 5.Patent 1,430,392 (Sept. 26, 1922). (13) Lupton, W. B., Ibid., 398,337 (Feb. 19, 1889). (14) McRae, F. W., Zbid., 1,684,593 (Sept. 18, 1928). (15) Murray, A , , Chem. & Met. Eng., 25, 473 (1921).
RSCEITEDJune 23, 1933. Presented before the Division of Paint and Varnish Chemistry at the 86th Meeting of the American Chemical Society, Chicago, Ill., September 10 to 15, 1933.
Effect of Catalysts on the Reaction between Olefins and Hydrogen Sulfide H. R. DTJFFEY, R. D. SNOW,’AND D. B,, .KEYES, University of Illinois, Urbana, Ill.
P
REVIOUSLY reported experiments on the thermal decomposition of naphtha solutions of mercaptans have shown the following percentages remaining : SOL-
CAPTAN
VENT
Butyl Isobutyl N-amyl N-amyl a Estimated.
MER-
TIME
MER-
Naphtha Naphtha Naphtha Naphtha
OF
TEMP.EXPOSURE C. 300 300
O
Sec.
475 425
360” 360a 153 185
CATALYBT
CAPTAN
RE-
REFER-
MAINING
% Nickel Nickel None None
21 28
18 81
E N C ~
(4) (4) (6)
(6)
These figures indicate that equilibrium conditions may be reached when a measurable quantity of mercaptan still remains. A determination of the equilibrium constants for reactions involving olefins, hydrogen sulfide, and the corresponding mercaptans should supply some useful fundamental data. As a first step toward the determination of the equilibrium constant, the effect of catalysts on the synthesis of mercaptans from ethylene or propylene and hydrogen sulfide was determined. Variables included type of catalyst, rate of gas passage, and temperature.
EXPERIMENTAL PROCEDURE MATERIALSAND METHOD. The propylene was tank propylene consisting of 96.7 per cent unsaturates, 0.2 per cent I
Present address, Phillip’s Petroleum Company, Bartleeville, Okla.
carbon dioxide, 0.3 per cent oxygen, 0.1 per cent hydrogen, 0.2 per cent carbon monoxide, 1.45 per cent saturated hydrocarbons, and 0.85 per cent nitrogen. The ethylene used contained 99 per cent unsaturates. The hydrogen sulfide used for the catalyst study on propylene (with the exception of the commercial nickel catalyst) contained 76.2 per cent hydrogen sulfide, 23.2 per cent hydrogen, and 0.6 per cent residual gas. That used in the work on the nickel catalyst contained 99 per cent hydrogen sulfide. The purity of the hydrogen sulfide used for the work on ethylene varied from 91 to 99 per cent, with hydrogen as the major impurity. CATALYSTS.The catalysts used were as follows: Activated fuller’s earth. Two different samples were obtained through the courtesy of oil companies. Activated charcoal, commercial grade. Silica gel, commercial grade. Silica aerogel, a specially prepared product having an apparent specific gravity of about 0.05. Thorium oxide. FiMeen grams of thorium nitrate were precipitated on 39 grams of pumice by evaporation of a water solution. This nitrate was decomposed by heating gradually from 230” to 370’ C. Decomposition was assumed complete when no more acid was given off. Hydralo (aluminum oxide), regular granular material. Alumina aerogel, a specially prepared product having an apparent specific gravity of about 0.05. Antimony sulfide on pumice. The pumice was impregnated with a solution of antimony trichloride in hydrochloric acid.
INDUSTRIAL A X 0 ENGISEERING CHEMISTRY
92
Vol. 26, No. 1
Hydrogen sulfide was passed through the mass until the sulfide liquid polymer divided by the weight of propylene, talwas formed and the hydrochloric acid was removed. Bentonite. Bentonite colloidal clay was moistened, rolled culated from the gas volume, was called the "percentage into balls, and dried. polymerization.'' Chabazite. This was a quite pure variety. The crystals were ANALYTICAL METHODS. The naphtha was diluted to either separated from accompanying rock and heated for 4 hours under 50 or 100 cc., depending on the amount of mercaptan formed. vacuum at a temperature of 340" C. Hydrogen sulfide was removed by acid cadmium chloride Phosphoric acid on activated charcoal. Activated charcoal was placed in the catalyst tube and well moistened with sirupy (6)* Mercaptan was determined by the method Of and Reid (1) 8s modified by Anding ( 6 ) . It was found phosphoric acid. Excess moisture was removed by heating the tube and passing through the hydrogen sulfide-propylene mix- desirable to keep the naphtha solution cold during the reture. moval of the hydrogen sulfide Nickel on kieselguhr, a comand subsequent titration of the mercial hydrogenation catalyst. The effect of catalyst, temperature (200' to mercaptan. Thjs procedure was Nickel s u l f i d e on p u m i c e . Nickel hydroxide was precipitated 300" C.), and time of contact o n thesynthesis of followed on all for the on the pumice by addition of ammercaptan from propylene and hydrogen sulfide ethylene and on the runs for monium hydroxide t o an aqueous solution of nickel nitrate. After has been determined. Several of the catalysts propylene Over the nickel catapromote polymerization or decomposition of the lyst* drying, h y d r o g e n s u l f i d e was passed over the catalyst until the Residual sulfur, after removal propylene at the space velocities studied. Among hydroxide had been converted into of the m e r c a p t a n , was deterthe sulfide. the best calalysts are nickel on kieselguhr, phosmined by the A. s. T. M. lamp phoric acid o n activated charcoal, and various m e t h o d and by the modified APPARATUS.T h e r e a c t i o n was carried out in an electriclays. &laximum conrersions range from 17 lamp method (3). Correction per cent at 2000 to 9 per cent at 3000 at space was made for the sulfur origically heated tube furnace having nally present in the n a p h t h a a heating section 30 long* velocities of 3 and 23, respectively. (0.000111 g r a m of sulfur per The catalyst tube was of Pyrex The ComParison Of catalysts is repeated on gram of oil). glass 18 mm. inside d i a m e t e r ethylene at 250" C. Nickel on kieselguhr is by a n d 23 c m . l o n g , a n d w a s IDENTIFICATIOS OF ~ I E R C A P far the most act& catalyst, converting 22.2 per TAN. D e n i g e ' s nitroprusside surrounded by a copper jacket to equalize the temperature. The cent the ethylene to mercaptan at a space test for mercaptans was positive (sulfides, sulfur d i o x i d e , capacity of the tube was about velocity of 3. alcohols, aldehydes, and hydro: 20 cc. The furnace was held gen sulfide do not i n t e r f e r e ) . constant to within *3" C. by means of a regulator. Temperatures were read on a chromel- The doctor test was also positive. The 2,4-dinitrophenyl alkyl sulfides were prepared after alumel thermocouple inserted in a tube sealed in the center of the method of Bost, Turner, and Norton ( 2 ) . Difficulty Tvas the catalyst tube. METHODOF OPERATION.Hydrogen sulfide and propylene found in purifying the propyl derivative, the melting pojnts or ethylene were measured and mixed in the ratio 1 to 1 by on three successive recrystallizations being 81O, 86", 88" C. volume. The mixture was forced from a containing flask by (melting point of the N-propyl sulfide, 81"; of the isopropyl saturated salt solution which entered the bottom a t a con- sulfide, 94.5" C.). It is possible that other mercaptans or stant slow rate. This salt solution was found to absorb from mercaptan-like bodies are present in the product. How10 to 20 per cent of the hydrogen sulfide. The gases after ever, the difficulty in purification may be due to the small passing through the furnace were run through a sintered glass amount of derivative available. The mercuric oxide derivative of ethyl mercaptan was prefilter containing naphtha and surrounded by a n ice bath. At the end of a run the naphtha was analyzed. No runs were pared. The product melted a t 75.2" to 75.8" C. (Reported made until a t least 6000 cc. of gas mixture had passed through melting point 76" C., 7.) The 2,4-dinitrophenylethyl sulfide the furnace. Runs were continued until no further increase was found to melt a t 115" C. A mixed melting point gave in percentage of mercaptan was obtained. During the entire 114" to 115" C. Sulfur analysis on the. derivative gave period of testing a catalyst (a week or more) the furnace was 14.00 per cent (theoretical, 14.20 per cent). held a t constant temperature. PROPYLENE Decomposition of the propylene was indicated by a deposit Table I gives a comparison of the various catalysts a t apof carbon on the catalyst. Polymerization, in the case of phosphoric acid, was determined by passing the pure propyl- proximately 200" C. They may be placed in three groups: ene through the catalyst and condensing the liquid product (1) good catalysts-nickel on kieselguhr and phosphoric acid in a trap surrounded by a n ice bath. The weight of the on charcoal; (2) fair catalysts-bentonite, fuller's earth, and
c.
TABLEI. EFFECT OF CATALYSTS OK YIELD OF PROPYL MERCAPTAN PROPYLENE CONVERTED SPACE
CATAL STS ~
VETEMF LOCITY ).
TO
MERCAP-
REMARKS
TAN
cc. g a s / c c .
c. Fuller's earth 1 hctivated charcoal Silica gel Thorium oxide Hydralo Antimony sulfide on pumice Fuller's earth 2 Silica gel (low sp. gr.) Bentonite Chabazite Phosphoric acid on charcoal
200 192 205 205
Nickel on kieselguhr
205
217
206
205 207 197 195
202
catalyst/ hr 23.1 17.7 15.0 14.7 16.5
12.6
15.3
20.7
17.7
% 4.5 5.7 2.0
0.2 2.6 0.2 6.5 0.7
8.5
18.0 17.7
0.3 14.8
12.9
14.3
Some polymerization and decomposition of propylene
..........
..........
Viscous red oil formed which collected in the exit tube. No polymerization of propylene, but considerable hydrogen eulfide could not be accounted for.
..........
Some polymerization and decomposition of propylene
.......... Some decomposition of ..........
propylene.
Polymerization of pro ylene to the extent of about 70 per cent: the polymer was a light oil,, colorless t o light yellow gut gradually darkening, and readily soluble in concentrated sulfuric acid; about 75% of the liquid distilled over in the range 40' to 120' c.
..........
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 R.I I S T R Y
January, 1934
93
v
activated charcoal; (3) poor catalysts- hydralo, silica gel, chabazite, antimony sulfide on pumice, and thorium oxide. The space velocities in every case are very low. Figure 1 gives the variation in yield with temperature for phosphoric acid, fuller's earth, and nickel on kieselguhr. Apparently the competing reactions (polymerization and decomposition) in the case of the fuller's earth and the phosphoric acid are influential in causing the rapid decrease in yield with increasing temperature. This decrease is much less marked with nickel on kieselguhr. The space velocities tried ranged from 73 to 1.9 cc. of gas per cc. catalyst per hour. The results with fuller's earth 2 a t a temperature of 200" C. are as follows: S P (CE
VELOCITY Cc g a s / c c catalyst/hr.
39 23 6 1
3 1 6 9
PROPILENE CONVERTED TO M E R C A P T ~ ?
% 4 4 4 5
11 6 16 4
Thus even a t low rates of flow, equilibrium probably had not been reached. However, a t 295" C. the nickel on kieselguhr gave the following results: 3 7 6 2 23 3 73.2
9 1 9.2 9 6 4.8
At this temperature, Kith the nickel catalyst, constant yields of mercaptan were obtained a t space velocities as high as 23.3. I n the case of the fuller's e a r t h a n d phosphoric acid catalysts, lamp s u l f u r determinations were made after B the removal of the mercaptan with excess silver n i t r a t e . There was no e v i d e n c e of 12 residual sulfur in the naphtha s. over that originally present i (limit of accuracy of the lamp $ 8 method, 1 per cent of the $ total hydrogen sulfide used for a run). With these cata4 lysts the formation of sulfur compounds not extracted by silver nitrate is slight.
f
2 00
Tempwuture,
300
C:
ETHYLEXE
FIGURE1. VARIATIOXOF The effect of catalysts on YIELDOF PROPYL MERCAP- the reaction between ethylene TAN WITH TEMPERATURE a n d h y d r o g e n sulfide was studied a t only one temperature, 250' C. Table I1 shows the comparative activity of the catalysts. In this reaction the nickel on kieselguhr is by far the most active catalyst, with hydralo and bentonite next in order of activity. Ethylene, like propylene, gave considerable liquid polymer in the presence of the phosphoric acid catalyst. With the exception of the hydrogenation catalyst, there was no evidence of sulfur remainingin the naphtha, over that originally present, after removal of the hydrogen sulfide and mercaptan. With the nickel hydrogenation catalyst about 1.2 per cent of
the sulfur was converted to products not removed by silver nitrate or doctor solution. TABLE 11. EFFECT O F CiTALYSTS O N YIELD O F ETHYL J4ERC i P T . 4 S AT
253"
c.
ETHYLENE CONVERTED SPlCE VELOCITY
Cc.
Chabarite Nickel sulfide on pumice Antimony sulfide on pumice Hydra!o Alumina aerogel Nickel on kieselguhr ~
TO lfERC.kPT.4S
catalust/hr.
gas/cc.
% 2.3 1.5 2.8 5.0 1.0 1.3 1.6 0.5 7.5 0.9 22.2
1.9 1.5 1.5
1.6 2.6 3.1
This work should not be const'rued as evidence either for or against, the intermediate CzHaSH CsHsSH I/ or CzHa czH>
