September, 1933
INDUSTRIAL ASD ENGINEERING CHEMISTRY
no more than 2 per cent of the benzene could have been hydrogenated even if the whole freezing point depression mas due to this alone. TABLE11.
KISETICS OVER
--
CaHaS REACTED
% 21 23 24 24 33 33 35 33 31
THIOPHENE VARIED
87 88 81 85 88 86 87
ACKSOJT-LEDGMENT The authors wish to express their thanks to Hugh S.Taylor who suggested this investigation.
Ct S-bfOOs CaTALYsT A T 200" c .
(1 iitmosphere total pressure) FLOW R ~ T E-INITIAL PAESSCRE __. 4 2000 ~ c. G H ~ Sx 103 H? c6Hs Sc./min. Atmuspheres--H Y D R O G E N .AND B E S Z E N E V I R I E D , S z A D D E D 90 3.32 0.329 0.678 89 3.29 0.328 0.672 90 3.23 0,321 0,359 0,350 89 3.15 0,325 90 3.21 0.643 0,357 0,354 90 3.19 0.646 90 3.19 0.646 0.354 0.317 85 2.86 0.683 85 2.86 0.683 0.317 1.67 1.67 2.78 3.07 3.28 6.70 6.70
0.659 0.659 0.712
0.341 0.341
0.682 0.660
0 318 0.340 4.328 0.332
66 70 52 50 46 38 39
0.375 0.310 0.404 0.358 0.386 0.367 0.350 0.390
17 23 34 34 49 49 53 74
0,672 0.668
0.288
1013
sUMIJIARY
I series of catalysts, including cobalt and molybdenuiii ~ 1 fides, has been tested in the removal of small quantities of thiophene from benzene by hydrogenation. An equimolecular mixture of cobalt sulfide and molybdenum oxide was the most active catalyst of those tested. At a space velocity (hours-') of 240, 0.5 mole per cent of thiophene was completely removed a t 325" C., with a 4H9:1C6Hs mixture. Detailed investigation of the reaction a t 200" C. in the presence of the cobalt sulfide-molybdenum oxide catalyst showed that the rate was little affected by changes in hydrogen or benzene concentrations. The order with respect to thiophene was less than the first, indicating either a nearly saturated surface layer of thiophene, or poisoning by-products.
F L O W R l T E Y'ARIED
a
b
3iO 336 195 179 94 92 89 47 !i = > 0.320 a t m . .U? 0.325 atm.
1.84 1.52 1.97 1.75 1.89 1.80 1.71 1.89
0.625 0.690 0.596 0.642 0.614 0.633 0.650
0.610
LITER-4TURE C I T E D
(1) Sllen, "Commercial Organic .4nalysis," 5th ed., p. 517, Blakiston,
1926. (2) Elgin, J. C., Wilder, G. H., and Taylor, H. S., IND.EXG.CHEM., 22, 1284 (1930); Elgin, Ibid., 22, 1290 (1930). (3) I. G. Farbenindustrie, British Patent 315,439 (May 24, 1928). (4) Mascarelli and Pestalozaa. dtti accad. Lincei, [2] 16, 574 (1907).
-
* * * * *
Part I1 ROBERTN. PEASEAND WENDELLC. MUNRO,Princeton University, Princeton, N. J.
I
N EXTENSION of the investigation reported in Part I, additional catalysts have been tested. The method and apparatus used are unchanged. Four catalysts were prepared as follows:
1. Cobalt oxide from the nitrate was reduced in hydrogen and subsequently treated with hydrogen sulfide gas to produce a surface layer of sulfide. 2. Cobalt sulfide and chromic oxide were co-precipitated from their nitrate solutions with ammonium hydroxide and hydrogen sulfide. The ratio was one mole COSto one mole Cr2CL. 3. Chromic oxide was precipitated from the nitrate with ammonium hydroxide. This catalyst retained much water at 110Oto 130" C. 4. Cobalt oxide and molybdenum sulfide were mixed in powder form. The ratio was one mole CosO, to one mole Yo&.
All catalysts were made into pills of which 25 cc. apparent volume were used. All samples were first treated with hydrogen at 400" C. and then with the hydrogen-benzene-thiophene mixture also at 400". Tests were made with a mixture of 1 mole benzene, containing 0.5 mole per cent thiophene, to 4 moles hydrogen. The total flow rate was 100 cc. per minute (normal temperature and pressure). Results for steady-state operation are given in Table I. TABLE
CAT.ALYST 1 2 3
4
I. EFFICIENCY
DEscI(IP'rIox Cobalt treated HzS COS-CrrOa CrlOs. zH?O Co-hloS?
OF
C.4TALYST.9 THIOPHENE REMOVED 200' C. 400" C. 38 0
37
I00
100 98
Comparison of these results with those of Keighton (Part I) indicates that catalysts 2 and 4 were as good as Keighton's best catalyst IIb (COS-Mooa). Catalyst 4 was much superior t o the corresponding preparation made b y Keighton. The
reason for this is not clear, since the only difference was that, after reduction, Keighton's preparation was treated with the reaction mixture first at 200" C. while Munro's preparation was first treated a t 400". The treatment a t 200" was intended to prevent carbonization. The inactivity of catalyst I was unexpected. Pure cobalt was found by Keighton to have moderate activity, whereas cobalt sulfide was next to the best catalyst. It might have been expected that' a surface layer of sulfide on cobalt would lie between, instead of being the least active. The explanation is presumably to be sought in the existence of a n unbroken layer of sulfur on the cobalt treated with hydrogen sulfide. Such a layer is probably firmly bound as compared to a similar layer on the fully saturated sulfide. Hence, interchange with the substrate would be more difficult. Presumably if the untreated metallic cobalt was exposed to the reaction mixture under such conditions that most of the sulfur remained on the surface, similar inactivity would have resulted. The fact that the hydrogen has access to the sulfur while i t is being laid down gives the untreated cobalt catalyst such activity as it possesses. SUMM.4RY
Cobalt sulfide plus chromium oxide, and chromium oxide alone are good catalysts for removal of thiophene from benzene by hydrogenation. Metallic cobalt pretreated with hydrogen sulfide is inactive, although untreated cobalt and cobalt sulfide are active. RECEIVED February 27, 1933. This paper containe results of an investigation carried out as part of Project 40 of American Petroleum Institute research. Financial assistance has been received from a research fund donated by John D. Rockefeller. This fund was administered by the hmerican Petroleum Institute with the cooperation of the Central Petroleum Committee of the National Research Council. Hugh S . Taylor of Princeton University was director of Project 40.
