November, 1941
INDUSTRIAL AND ENGINEERING CHEMISTRY
from unleaded isooctane to isooctane plus 3 cc. tetraethyllead is about equal to that from 75 to 100, or from 0 to 75 octane number. On the supercharged C. F. R. engine the indicated power output is substantially proportional to the manifold pressure a t constant-mixture strength, and therefore the power output at incipient detonation for any given fuel is proportional to its allowable boost ratio. If we call the power output possible on isooctane 100 per cent, then under a certain set of
1373
engine conditions isooctane plus 3 cc. tetraethyllead permits, say, 140 per cent power, and a 75 octane number fuel, 65 per cent (Figure 4).
Literature Cited (1) Boerlage, G.D., Peletier, L. A., and Tops, J. L., Aircraft E w . , 7, 306-8 (1935). (2) Hebl, L. E., Rendel, T.B., and Garton, F. L., IND. ENG.CHEM., 25, 187-91 (1933). (3) Ibid.. 31, 862-5 (1939).
Catalytic Poisoning in Liquid-Phase Hydrogenation Effect of Sulfur Compounds of Various Degrees of Oxidation Catalytic hydrogenation is an established process in the vegetable oil, petroleum, and chemical industries. In many cases process designs, costs, and operating schedules are greatly affected by the presence of catalyst poisons. Results are presented on the poisoning effect of sulfur compounds of various degrees of oxidation.
HE poisoning effect of sulfur compounds on nickel
T
catalysts has been observed in many instances Ellis and Wells ( 2 ) showed that bromine, iodine, antimony bromide, sulfur, phosphorus, sulfur chloride, arsenic, mercury, and lead have a distinct poisoning effect on the hydrogenation of cottonseed oil with a nickel catalyst. Hydrogen sulfide, sulfur dioxide, and chlorine were also shown by Moore, Richter, and Van Arsdel (6) to destroy the catalytic activity of nickel. However, sodium sulfate, sodium chloride, sodium nitrate, and nickel chloride were without effect. Sodium sulfide gave a gradual poisoning effect. Ueno (8)in an exhaustive investigation of the hydrogenation of oil with a nickel catalyst found a retarding effect by soaps of potassium, sodium, lithium, magnesium, barium, beryllium, iron, chromium, zinc, cadmium, lead, mercury, bismuth, tin, uranium, and gold, while the soaps of calcium, strontium, aluminum, cerium, nickel, manganese, copper, silver, vanadium, thorium, and platinum had no effect upon the catalytic action. Nickel acetate, butyrate, stearate, lactate, oxalate, and succinate had also no influence on the catalytic hydrogenation. Fatty acids, such as acetic, lauric, stearic, and oleic, had no influence on catalytic action, but glycolic and lactic acids, hydroxystearic acids, oxalic, succinic, and fumaric acids, and hydroxy acids such as malic, citric, and tartaric acted as catalyst poisons. Sodium taurocholate had a restrictive influence while nucleic acids had no effect. Proteins, blood albumin,
A. GARRELL DEEM AND JOSEPH E. KAVECKIS University of Illinois, Urbana, Ill.
blood fibrin, and gelatin showed a restrictive influence, but hemoglobin was inert. Glycerol and lecithin had considerable action, but cholesterol and squalene were ineffective. Carbohydrates such as sucrose, dextrose, mannitol, and starch behaved as negative catalysts, but glycogen had no influence. Alkaloids such as morphine and strychnine were pronounced poisons. Kelber (8) found that nickel catalysts made in various ways behaved differently toward poisons such as hydrocyanic acid or potassium cyanide, hydrogen sulfide, and carbon disulfide when used for the hydrogenation of sodium cinnamate in aqueous solution. The effect of ethyl mercaptan on the kinetics of the hydrogenation of ethyl cinnamate was investigated by Schwab and Brennecke (7). Maxted and Evans (6)were able to show that the poisoning effect of hydrogensulfide, carbon disulfide, thiophene, and cysteine varied directly as the concentration of the poison. Kubota and Yoshikawa (4) found that, while thiophene inhibited the reaction of benzene to cyclohexane,the nickel catalyst so poisoned was still active for the hydrogenation of phorone. Later Yoshikawa (9) studied the effect of thiophene on the relative activities of nickel and nickel-copper catalysts for the hydrogenation of benzene. The nickel-copper catalyst was found to be poisoned to a lesser degree than the plain nickel catalysts. From these investigations the qualitative generality may be drawn that the poisoning effect of acids, halogens, soaps, m d sulfide sulfur compounds are dependent on the catalyst used and the material to be hydrogenated. No work, however, has shown the effect of sulfur of intermediate stages of oxidation between sulfide sulfur and sulfate or sulfonate sulfur. Since the progress of hydrogenation is of fundamental importance to the vegetable oil, petroleum, and chemical industries, more complete information of the effect of sulfur compounds of all types, especially sulfides, sulfoxides, sulfones, and sulfonic acid salts and esters, would be of value'. For this investigation Raney nickel was selected as the catalyst, because of ease of preparing batches with reproducible activity. Phenol, naphthalene, and quinoline were chosen as the materials to be hydrogenated because of the ease with
1314
INDUSTRIAL AND ENGINEERING CHEMISTRY
which they may be prepared pure, and also because of the absence of complicating side reactions.
Materials and Method The catalyst was prepared ( I ) from Raney nickel, a finely divided alloy of nickel and aluminum. T w o hundred grams of Raney catalyst were added slowly over a period of 145 minutes to a solution of 160 grams of reagent-grade sodium hydroxide, dissolved in 840 cc. of distilled water contained in a 3-liter beaker cooled by tap water. The mixture was heated on a hot plate for 4 hours with occasional stirring a t 105-110' C. Then 268 cc. of the sodium hydroxide solution were added, and the mixture was heated for 2.5 hours; after that time bubbles of hydrogen were no longer evolved. A 1250-cc. partion of distilled mater was added and the sodium aluminate decanted. The nickel was washed with distilled water by decantation until the decanted liquid was neutral to litmus. The catalyst was then washed eight times with absolute alcohol and kept in a loosely corked bottle.
Vol. 33, No. 11
A 400-atmosphere chrome-vanadium steel bomb was used for a reaction chamber. The net volume of the bomb was accurately determined t o be 355 cc. During the course of the hydrogenation the bomb was oscillated 15' above and 15" below the horizontal in a shaking machine (Figure 1) running a t the rate of ninety oscillations per minute. Temperatures were measured by an iron-constantan thermocouple with a Leeds & Northrup portable-type potentiometer, with an accuracy of *LO" C. Pressures were measured with a 0-5000 pound per square inch, 8-inch, Crosby pressure gage. To obtain reproducible results, each run was made in the following manner: (a) The bomb was rinsed with acetone, steamed for a minimum of 15 minutes, rinsed again with acetone, dried by air, and then wiped with a clean towel. (b) Fifty grams of hydrogen acceptor and 5 grams of catalyst were weighed into the bomb. When a sulfur compound was used, it was weighed directly into the bomb if solid, or by a tared eye-dropper bottle if liquid. (c) The bomb was closed and placed in the shaking machine, and hydrogen was admitted. For phenol and quinoline a pressure of 1600 pounds per square inch was used; for naphthalene, 1800 pounds per square inch. (d) After the hydrogen was admitted to the bomb, the temperature was raised to the desired value, which was 120" C. for phenol. In the hydrogenation of quinoline, substantially constant temperatures of 130" C. for the first stage and 230' for the second were used; for naphthalene 130' C. was used for the first stage and 190" for the second. The point of temperature change can, of course, be identified on the curves by the sudden increase in the rate of hydrogen addition after the first stage is complete. For low rates of absorption, pressure readings were taken at 20-minute intervals; for high rates, pressure readings were taken every 5 minutes. When the pressure had decreased to 1000 pounds per square inch, more hydrogen was admitted until the original pressure was restored. This addition of hydrogen was made as quickly as possible. Each run was for a t least 4 hours or until the pressure remained constant for a t least 20 minutes. After the run, the bomb was cleaned as in step a, and the procedure was repeated with pure phenol 2nd catalyst to be certain that all poisoning compounds had lieen removed. It was found that 45 minutes of steaming removed the sulfur compounds completely.
Calculations The quantity of hydrogen absorbed was calculated from the pressure drop since the volume of the bomb, weight of the sample, and temperature were known. In making the calculations the following assumptions were made:
FIGURE 1. SHAKING MACHINE AND PROTECTIVE BARRICADN
The phenol used was U. S. P. grade packed by the J. T. Baker Chemical Company and by Merck and Company. Hydrogenation tests revealed no apparent difference between the batches used. Polar brand moth flakes,, packed by The Barrett Company, were refluxed with sodium t o produce purified naphthalene. To 345 grams of moth flakes, 8.5 grams (2.5 per cent) of sodium were added. After refluxing for 9 hours, the naphthalene was distilled into a glass container. Attempts t o purify Barrett's quinoline by refluxing with sodium, sodium hydroxide, and Raney nickel catalyst were unsuccessful. Synthetic quinoline from Eastman Kodak Company was therefore used. All poisons were pure compounds from Eastman.
1. The vapor pressure of the acceptor and the resulting product had a negligible effect upon the total pressure. At 115' C. the va or pressure of phenol is 1.54 pounds per square inch. 2. !'he change in compressibility factor of hydrogen is negligible. 3. The density of the solution does not change during the course of the reaction. 4. The solubility of hydrogen in the solution may be neglected.
Calculation for the amount of hydrogen absorbed a t any time, 8, may be made by the expression: gram atoms of hydrogen absorbed = 2(Vo o - Vs) 22,400 X N gram moles of hydrogen acceptor where N = gram moles of acceptor used V = volume of hydrogen gas corrected t o standard conditions at time B Typical data are shown in Table I. Complete data are given in Figures 2, 3, and 4.
W
z
(boiling point 157' C.) was suspected. However, no such derivative could be made. Therefore the hydrogenation produced only cyclohexanol (boiling point 161' C.). This result may be explained as a delayed poisoning effect which caused the reaction rate to decrease to zero after only two thirds of the theoretical quantity of phenol had been converted to cyclohexanol. By delayed poisoning effect we mean that diphenyl sulfone itself is not a poison, but that a poison, such as thiophenol, is generated by reduction and hydrogenolysis of the diphenyl sulfone. Obviously, as increasing quantities of thiophenol are produced, the catalyst will become progressively less effective and finally exhibit complete inactivity. This result is especially worthy of note in view of the widely used procedure of determining the quantitative amount of unsaturation in organic research. That is, in every respect except the amount of hydrogen added, a hydrogenation in the presence of a delayed poison is similar to the hydrogenation of a pure compound. Therefore, for the method of determining amount of unsaturation by hydrogenation to be trustworthy, a hydrogenation must be carriedout in which the equilibrium is approached from both sides. I n cases in which the reaction is irreversible, the method is open to question. I n the case of naphthalene two distinct stages of hydrogenation occur-namely, to the tetra- and decahydronaphthalene. Likewise, two distinct regions of poison characteristics are noted. I n the low-temperature region used for the hydrogenation to tetrahydronaphthalene, substantially the same conclusions may be made as were drawn for phenol. In the high-temperature region, however, i t appears that all sulfur compounds from thiophenol to methyl-p-toluene sulfonate are either immediate or delayed poisons. Presumably, as a result of the high temperature involved, the sodium benzene sulfonate, methyl-ptoluene sulfonate, and diphenyl sulfone are gradually reduced to active poisons. Similar conclusionsmay also be drawn in the case of quinoline with regard to the relation between ease of reduction, temperature, and delayed poison activity,
"/'
CII
~
we -I
I 6 !,---0.6
I
G
M E T W L - P A R A - TOLUENL SULFONATE
I
0.5 G.
20
40
1 60
20
40
60
DIPHENYL W L F I D E
I
I
80
100
120
140
100
1
80
100
120
140
I60
! I' 4 I
I
180
we
E
_I
U w -14
2
9
e
