234
11. C . GRILLS .4ND 0. n'. BROWN
CXTALYTIC REDUCTIOS OF NITKOBESZESE I S T H E LIQUID PHASE 11. c. GHILIaS A K D 0 . \v. BHO\YS Luboratory o j Physical Chemistry, Iildiana Unioersity, Bloomington, Indiauu
Received April 18, 1940 INTRODUCTIOii
In this investigation a study was made of the liquid-phasc reduction of nitrobenzene. The reduction was carried out with a metallic copper, lead, or bismuth catalyst undcr a pressure of 500, 1000, or 1500 pounds per, squarc inch and a t tcmpcraturcs varying from 200" to 360°C. The time of esporimcnt ~va8also varied. Brown, Etzel, and Hcnkc (2) harr published data conccwiing the us(' of nickel catalyst iii th(1 liquid-phase reduction of iiitrocompounds. Adkins and coworkers (1) have used nickel and copper chromium oxide as catalysts in the liquid-phase reduction of nitrobenzene. S o published data was found 011 the use of a metallic copper, lead, or bisniut,l~as catalyst in thv liquid-phase reduction of nit,robcnzene. .\PP.iHITTS. M.%TEIIIALS, . W D .I?iALTSIS
Tht: apparatus used was a high-pressure hydrogenation apparatus Nodel W3C, manufact,urcd by the Parr Instrument Company of Aloliiie, Illinois. The procedure of coiiducting experiments with the apparatus is described in a pamphlet published by the Parr Instrument Company. Thcb niatcrials i w d were purified and the products analpcd in thc maiinw described by Brown. Etzcl, and Henke (2). PREPAIlATIOS OF CAT.%Ll-ST
Cupric acetate wax dissolved in hot distilled water and sodium hydrosidc was nddcd to ,scc,nre complete precipitation of copper hydroxide. The hpdroxidc was washcd, dried overnight at 110°C. and reduced wit'h hydrogen. Thc temperature of rcduction was 360°C. for catalyst S O .1 and 260°C. for catalyst S o . 2 . The catalyst was always filtered from the produc:t,s and usrd in the nest cxpcriments. ~
HPSULTS
From t a l h 1 it, can be seen that the niasimuni yield with cntalystsSo. 1 and S o . 2 is a t 270°C. f5" under the conditions studied. Copper cat.alysts Tvhich had been reduced eithcr at 360°C. or at 260°C gave approximately the samch yicld of nnilinc, when used at 270°C. -f 5'. Hoivevcr, a t a temperature higher or lower than 270°C. 5", the catalyst which had bccn reduccd a t 36O"C!. gavc t,lic better yield of aniline.
*
C.\T.\LYTIC
235
REDVCTIOS OF S I T R O n E S Z E S E
Esperinientc \\ere conductcd with catalpts So. 1 :uid S o . 2 to see if increasing or decreasing the time of run would improi c’ the yield of aniline. The esperinirnts were conducted undcr the bwt eonditions of temperature and pressure as given in table 1. I t was found that the yield of anilinc decreased nlicn thc time was rithcr decreased from 2 Iir. to 1 hr. or increased from 2 hr. to 3 hr. When experiments ~ e r made e with a pressure of 1500 pound., :i time of run of 2 hr , and a temperature of 270°C., approsimately the same Jield of aniline nas obtained as with a pressure of 1000 pounds. Howc~er, when the pressure was reduced to 500 pounds, the yirld of aniline was decreawd from 94 to 83 per cent. .i study qhould be made of the effect of varying the amount of catalyst in rclation to the amount of nitrobenzene. TABLE 1 Reduction of nitrobevteire i t &the Ziquid phase Time of run, 2 hr.; pressure, lo00 pounds per square inch; anioiint of nitrobenzene, 4.7366 g.; amount of catalyst, 2 6. CATALTdT NO.
Temperature
-___
.
‘C
200 212
Yield of aniline
I
per c e d
I
30
I
91t 90
270&5
300 325
1
I
-
~
‘C.
300
Yield of auilino
=-I I
--20
I
89.5’
85
I
Temperature
270 315
5
j
93%
i
55
I
* Average of two experiments. t .iverage of eleven experiments. t Average of seven experiments. The w e of 10 ml. of benzene or 10 ml. of ab-olutc alcohol as solvent under the best condition of temperature, prcssurc. and time of run did not increase the yield of aniline. However, in the reduction of nitro compounds in which the starting matcrial or the product.; arc solid. a solvent might increase the yield. A study was made of a lead catalyst prepared by the rcduction of Hammond‘ red lead a t a temperature of 31OoC. The conditions of the esperiinent were a temperature of 260’ to 360°C. and a p r e w ~ r cof 500 to 1000 pounds, and the time of run was varied from 1 to 2 hr. The ratio of with the catalyst to nitrobenzene was the S ~ I Cn.: in thc c~\pcrimcnt~ copper catalysts. The niasimum yield was 7.5 per cvit anilinc a t a tem1 Hanimond red lead, obtained from the Hanimond Lrad I’roducts, h e . , Hammond. Indiana.
236
W. 0. EVERBOLE AND D. L. DEARDORFF
perature of 310"C., a pressure of 1500 pounds, and a time of run of 2 hr. A metallic bismuth catalyst prepared by the redKction in hydrogen of bismuth hydroxide a t 320" to 340OC. was studied under the same conditions as the metallic lead catalyst. The maximum yield obtained was 45 per cent of aniline a t 31O'C., a pressure of lo00 pounds, and a time of run of 2 hr. CONCLUSIONS
1. The copper catalysts studied gave yields of aniline as high as 89.5 per cent t o 94 per cent over a temperatw-e range of 242' to 300"C., the pressure being lo00 pounds and the time of run 2 hr. 2. Copper catalysts reduced from the oxide at either 260" or 360°C. gave, within experimental error, the same yield of aniline. The best results were obtained at a temperature of 27OOC. This is approximately the temperature, 260" to 265"C., that gives the best results in the vapor phase (3). 3. A metallic lead catalyst and a metallic bismuth catalyst prepared and studied under the conditions described are nobgood producers of aniline. REFERENCES (1) ADKINS,HOMER: Reaction of Hydrogen w i t h Organic Compounds over CopperChromium Oxide and Nickel Catalysts, p. 95. Vniversity of Wisconsin Press, Madison, Wisconsin (1930). (2) BROWN, 0. W., ETZEL,G., AND HENKE, C. 0.:J . Phys. Chem. 88, 831-5 (1928). (3) BROWN, 0.W., AND HENKE,C. 0.:J. Phys. Chem. #, 161-90 (1921).
FLOW POTENTIALS THROUGH METALS W. G . EVERSOLE AND D. L. DEARDORFF Division of Phyeical Chemistry, State University of Iowa, Iowa City, Iowa Received March
1 , 19.40 '
In connection with attempts to measure potential differences set up by a stream of liquid flowing through a gas (I), it became necessary to measure potentials set up by flow through a small hole in a platinum disc. Thqse potentials increased with increasing pressure, and the deviations from a linear relationship between the potential difference and the pressure were such as might be,expected from the failure of Poiseuilie's law to apply to this type of flow. Such potential differences set up by the flow of liquids through metals have been measured by other investigators (3, 4), but their significance has not been satisfactorily explained. The
