How Du Pont's ESC A solved the case of the poisoned catalyst. A manufacturer who was using a palladi um-on-carbon catalyst in a chemical process to reduce a nitrogen-containing organic com pound noted that, after extended use, the catalyst lost its activity. Using bulk analyses such as x-ray fluo rescence, he determined that the total pal ladium content of the catalyst remained
constant after use. He suspected a catalyst poison such as sulfur or a halogen. But he had no proof. Surface analysis of samples of Fresh, Used-but-active, and Spent catalyst made with a Du Pont 650B Electron Spectrometer produced the following three spectra, shown at left below.
PALLADIUM-ON-CARBON CATALYST
FRESH
From these data, obtained in less than an hour, he determined that loss of activity was not caused by sulfur or halogens. Instead, it was due to formation of a nitrogen-containing by-product of the reaction which coated the surface of the catalyst, blocking the active palladium sites. ESCA—Electron Spectrometry for Chemical Anal ysis—has proved its unique capacity for surface analysis in the heterogeneous catalyst field. The sensitivity, speed and ease of use of the Du Pont 650B may prove valuable in your field. For more information on the Du Pont 650B and a descriptive brochure that takes the mystery out of ESCA, write Du Pont Instruments, Room 23956, Wilmington, DE 19898.
USED-BUT-ACTIVE
SPENT
DUΡΟΝT Instruments REG. U.S.PAT.OFF.
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A N A L Y T I C A L CHEMISTRY, VOL. 46, NO. 14, DECEMBER 1974 · 1259 A
