tant. Methyl or ethyl groups attached to the second carbon appeared optimal. The pentyl group was too large and caused steric effects. The effect of main chain length on drag reduction was minimal, although a longer main chain resulted in higher solubility and much easier dissolution. Acknowledgments This work was supported in part by the National Science Foundation. The Ohio State University donated the computer time. Synthetic Products Company prepared all the aluminum disoaps and donated a substantial fraction of the materials. Dr. Quentin Van Winkle assisted with the light scattering measurements.
Nomenclature CMC = critical micelle concentration, concentration below which soap is unaggregated in solution D = inside tube diameter, f t f = Fanning friction factor, eq 1 f' = friction factor calculated from eq 3 a t the same velocity as f g, = gravitational conversion constant K' = constant in Rabinowitch-Mooney eq 5 L = tube length, f t n' = constant in Rabinowitch-Mooney eq 5 N R = ~ Newtonian Reynolds number, D V p / h N R =~ Reynolds ~ number based on solvent viscosity, eq 2 P = pressure, AP is pressure drop, lbJft2 V = average tube velocity, ft/sec
hs
= solvent viscosity, lb,/(ft sec)
p = solution density, lb,/cu
ft
L i t e r a t u r e Cited Agoston, G. A,. eta/., lnd. Eng. Chem., 46, 1017 (1954). Baker, H. R., Bolster, R. N., Leach, P. B..Little, R. C., lnd. fng. Chem. Prod. Res. Dev., 9, 541 (1970). Baxter, R. A,, M.S. Thesis in Chemical Engineering, The Ohio State Universi-
ty, 1968. Brodkey, R. S.,"The Phenomena of Fluid Motions," Addison-Wesley, Reading, Mass., 1967. Debye, P., Ann. N.Y. Acad. Sci., 51, 575 (1949). Hershey, H. C., Ph.D. Dissertation, University of Missouri at Rolia, 1965. Hoyt, J. W., J. Basic Eng., Trans. A.S.M.E., Ser. D, 94 (2),258-285 (1972). Kuo, J. T., Ph.D. Dissertation, The Ohio State University, 1973. Lee, K. C., Zakin. J. L., AlChE Symp. Ser. No. 130, 69, 45 (1973). Lee, W. K., Vaseleski, R. C., Metzner, A. E., A.l.Ch.€. J., 20, 128 (1974). Ludke. W. 0.. Wiberley, S. E.. Goldenson. J., Bauer, W. H., J. Phys. Chem.. 59, 222 (1955). McMillan. M. L., Ph.D. Dissertation, The Ohio State University, 1970. McMillan, M. L., Hershey, H.C., Barter. R. A,, Chem. Eng. Progr. Symp. Ser., 67.No. 111.2711971). Ostwald, W., diedei, R., Kolloid-Z., 69, 185 (1934). Ousterhout, R. S.,Hall, C. D., J. Pet. Techno/., 13, 217 (1961). Patterson, G. K.,Zakin, J. L., Rodriguez, J. M.. lnd. Eng. Chem., 6 1 (l),22
(1969). Radin, I., Zakin, J. L., Patterson, G. K., in "Viscous Drag Reduction,'' C. S. Wells, Jr.. Ed., p 213,Plenum Press, New York, N.Y., 1969. Savins, J. G., J. lnst. Pet., 47, 329 (1961). Savins, J. G., Rheol. Acta, 6, 323 (1967). Savins, J. G., U S . Patent 3,361,213 (1968). Savins, J. G.,in "Viscous Drag Reduction," C. S. Wells. Jr., Ed.. p 183.Plenum Press, New York, N.Y.. 1969. Sheffer. H., Can. J. Res., 268, 481 (1948). Shiba. S.,Bull. Chem. SOC.Jpn.,33, 1563 (1960). Shiba, S.,Bull. Chem. Soc. Jpn., 34, 194,198 (1961). Virk. P. S.,Merrill. E. W., Mickley, H. S., Smith, K. A., in "Modern Developments in Mechanics of Continua." S. Eskinazi, Ed.. Academic Press, New York, N.Y., 1966. Virk, P. S., J. FiuidMech., 45, 417 (1971). White, A,, Nature(London), 214, 585 (1967).
Greek Letters solution viscosity, lb,/(ft sec)
Received for review December 23,1974 Accepted M a y 24, 1975
1=
Preliminary Assessment of Catalyst Pore Size Effects on Sulfur Removal from a Coal Derived Liquid Matthew C. Sooter and Billy L. Crynes* School of Chemical Engineering, Oklahoma State University, Stillwater, Oklahoma 74074
The effect of changing the average catalyst pore size radius from 33 to 25 A for a cobalt-molybdate on alumina catalyst resulted in a loss in desulfurization capability while hydroprocessing raw anthracene oil, a coal derived liquid. For these catalysts which have essentially identical chemical compositions and which are shown to be operating without the usual pore diffusion limitations, the shift to a smaller average pore size still resulted in lower sulfur removal. Possibly two surface phenomena are acting to limit the small pore catalysts: (1) a change in intrinsic surface activity or (2) restriction in reactant molecular orientation for proper adsorption for surface reaction. The data are presented and discussed; however, in this preliminary study, the controlling surface phenomena cannot be assessed, although an evaluation of the sulfur content of liquid product fractions suggests that there is no change in intrinsic activity.
Introduction With the increasing interest in the United States on the conversion of coal into convenient gaseous and liquid forms of energy, the potential need for catalysts for hydrotreating coal liquids has also increased. Much effort has been given to catalyst development for hydrodesulfurization of petro-
leum stocks, whereas relatively little has been directed toward those for coal-based liquids. The work reported here is a part of a larger program given to tailoring hydrogenation catalysts explicitly for coal-based liquids. These studies were made in the earlier phases of our program and are presented here to help establish communications with Ind. Eng. Chem., Prod. Res. Dev.. Vol. 14, No. 3, 1975
199
others working to develop coal processing catalysts. Much of the catalyst development work receives limited distribution in that proprietary arts must be protected. The Pittsburg and Midway Coal Mining Co. has developed a solvent refined coal process which produces a valuable, low sulfur-low ash fuel (Office of Coal Research, 1970a,b; Kloepper et al., 1965). Lighter liquid solvents are produced and used in the process, and such liquids have been of interest in this study.
0bjec tive The objective of this work was to make initial assessments of the effects of catalyst support pore properties on hydrodesulfurization of a coal liquid. Three cobalt-molybdate on alumina catalysts were obtained from a catalyst vendor for use in this work. The liquid used was a raw anthracene oil which was analogous to a solvent oil produced in The Pittsburg and Midway Coal Mining Co.'s solvent refined coal process. The catalysts were to have essentially the same chemical composition and total surface area but with differing catalyst support pore size frequencies and pore distributions. The ability of these three catalysts to remove sulfur from the raw anthracene oil was studied in a typical packed-bed, trickle flow reactor. Coal Liquid Feedstock The properties of the raw anthracene oil are shown in Table I. This oil was obtained from Reilly Tar and Chemical Corp. and served as a liquid analogous to a solvent fraction produced from The Pittsburg and Midway Coal Mining Co. solvent refined coal process. Obviously, liquid feedstocks from the process itself were preferable; however, in the earlier phases of our work such stocks were not available. The sulfur concentration in the feed liquid was 0.48 wt %, with essentially no ash components, and it had an ASTM distillation range of 193OC (380'F) to over 435OC (815'F). Catalyst Properties The catalysts used in this study were obtained from a vendor and were known to be good hydrodesulfurization catalysts for heavier petroleum feedstocks. One catalyst was commercially available (catalyst C), and the other two were from research batch production runs. All were extrudates. The metals content was the same, and the total catalyst surface areas were approximately equal. The BET areas were determined by an independent commercial testing laboratory as were the mercury penetration tests. The pore properties were characterized by 60,000 psi mercury penetration tests, and these test data were used to characterize the pore properties of the support. General catalyst properties are shown in Table 11. The composition of the catalysts was 3.5 wt % COO and 12.5 w t % MoOa; surface areas fell within 240 to 300 m2/g. The mercury penetration data were used to calculate a pore frequency plot for each catalyst, and these are shown in Figure 1. In this figure of dV/d(ln r ) vs. r, V is the accumulative pore volume and r is pore radius. Note that the three catalysts are single modal. Catalyst C has a more frequent pore size a t about 33 8, radius, and those for catalysts A and B are a t 25 8,. Catalyst B has a somewhat broader frequency than that for catalyst A. A greater difference in the pore properties of these test catalysts would have been desirable; however, availability and preparation limitations dictated choices of catalysts. Reactor Description The reactor used in this study was a 1.27 cm (0.5 in.) i.d. tubular packed bed, trickle flow reactor. Typical catalyst 200
Ind. Eng. Chem.. Prod. Res. Dev., Vol. 14, No. 3, 1975
Table I. Feed Oil Properties 90.65 wt 5.76 wt 0.48 wt 0.91 wt 2.2 wt
Carbon Hydrogen Sulfur Nitrogen Oxygen Ash
% % % % %
Nil
API gravity Init ialn 10 vol % 30 vol % 50 vol % 70 vol % 90 vol %
@
-7 193°C 232°C 297°C 343°C 371°C 435°C
60°F
(380°F) (450°F) (570°F) (650°F) (700°F) (815°F) * Normal boiling data determined from ASTM D 1160 data.
Table 11. Catalyst Properties A
C coo, wt MOO,, wt Support Pore volume, cm3/g Surface area, m2/g Most frequent pore radius, Size a
B
3.5 12.5 Alumina 0.463
3.5 12.5 Alumina 0.461
3.5 12.5 Alumina 0.566
240(270")
298
303
33
25
25
8/10 mesh
8/10 mesh
8/10 mesh
Ab
Vendor data. Taken from Figure 1.
PO
~ iADkI u
