TITLE: Metal Particle Characterization of Zeolite-Based Syngas Conversion Catalysts.

AUTHOR: V. U. S. Rao; R. T. Obermyer; A. Shamsi; R. K. Wicker; R. J. Gormley.

INST.  AUTHOR: Department of Energy, Pittsburgh, PA. Pittsburgh Energy Technology Center.

SPONSOR: Pennsylvania State Univ., McKeesport. Dept. of  Physics. *Washington

and Jefferson Coll., Washington, PA.*Department of Energy, Washington, DC.


PUB.  TYPE: Technical Report

PUB.  COUNTRY: United States

SOURCE: Department of Energy [DE],  1984,  9p.


NOTES: 188. meeting of the American Chemical Society, Philadelphia, PA, USA, 26 Aug 1984.


In this study it has been demonstrated that magnetic and chemisorptive techniques can be used to characterize metal speciation in catalysts such as Co/ZSM-5. In particular, the amounts of ion-exchanged cobalt and cobalt external to the zeolite can be estimated. These measurements enable one to intepret the catalytic activity and selectivity of the catalyst. In our attempts to introduce cobalt in cationic form in ZSM-5 we have used a temperature of 90 exp 0 C for exchange with aqueous cobalt nitrate solution. It appears that 0.9 wt % Co can be introduced into ZSM-5 of SiO sub 2 /Al sub 2 O sub 3 = 38 under these circumstances. Co/ZSM-5 samples that were prepared by impregnation at room temperature with cobalt nitrate solution, showed approximately 2.2 wt % Co to be in a form not reducible to metallic cobalt. In earlier work the Co/ZSM-5 samples were subsequently washed with water to yield samples that contained 1.4 to 1.7 wt % Co. It is hence possible that exchange at temperatures lower than 90 exp 0 C would yield samples containing more than 0.9 wt % Co in ion-exchanged form. It is shown in this study that Co exp 2+ /ZSM-5 can be back-exchanged and reduced to yield metallic cobalt supported on H-ZSM-5. Chemisorption measurements are currently being carried out to determine the degree of dispersion of such samples. The back-exchanged samples are  catalytically active in synthesis gas conversion. The method of back-exchange should be generally applicable for preparing metal-zeolite catalysts where it is desirable to free the zeolite of metal cations in order to restore the acidity to its original strength, and to have the metal on the exterior of the zeolite crystallites in a highly dispersed, catalytically active form. 14 refs., 2 figs., 3 tabs. (ERA citation 10:036300)