TITLE: Elektronen- und massenspektroskopische Untersuchungen oberflaechenchemischer Reaktionen der Fischer-Tropsch-Synthese an feinverteiltem, hochgestoertem Nickel auf Cordierit-Traeger. (Electron and mass spectroscopy for investigating chemical surface reactions of the Fischer-Tropsch synthesis on finaly dispersed, highly disordered nickel on cordierite substrates)

AUTHOR: H.P. Matsen Kohfahl.

INST.  AUTHOR: Hamburg Univ. (Germany, F.R.). Fachbereich 12 - Physik.

LANGUAGE: German

PUB.  TYPE: Technical Report

PUB.  COUNTRY: Germany Federal Republic

SOURCE: Other [$TFFIZ],  28 Sep 93,  185p.

NTIS ORDER NO.: TIB/A95-03805INW

ABSTRACT:

The hydrogenation of carbon of the technologically important Fischer-Tropsch-synthesis, nCO+(2n+1)H(2) ->C(n)H(2n+2)+nH(2)O, was investigated on finely dispersed, highly disordered nickel on technical cordierite supports under UHV conditions by electron and mass spectroscopy. The investigation of the Fischer-Tropsch-synthesis was carried through on highly disordered nickel made of formate precursors.  Surface loading with carbidic carbon and oxygen, important for the synthesis, was obtained by segregation of both out of the volume.  Subsequently, after exposure to 360000L of hydrogenation below 140K in a separate preparation chamber, carbon and oxygen were hydrogenated.  TDS-measurements of all important masses show the dominant generation of H(2)O and C(2)H(x) and, in parallel reactions, the generation of CH(x) and CH(x)O. The formation of carbidic C(2)-carbon was found to depend on the surface geometry of the nickel. While the close packed (111)- and (100)-interfaces are suitable catalysts for the methan-synthesis, carbidic C(2) adsorbates are formed at the grooves and the steps of the disordered nickel surface below 200K. The control of the catalytic selectivity of the hydrogenation of carbon is not only governed by the material of the catalyst: an essential influence is exerted by the surface geometry as due to preparation. (orig./EF). (Copyright (c) 1995 by FIZ. Citation no. 95:003805.)