TITLE: Multifunctional Cobalt-Zeolite Catalysts for Fischer-Tropsch Synthesis.

AUTHOR: G. Linden.

INST.  AUTHOR: Kernforschungsanlage Juelich G.m.b.H. (Germany, F.R.). Inst. fuer Grenzflaechenforschung und Vakuumphysik.

SPONSOR: Technische Hochschule Aachen (Germany, F.R.).


PUB.  TYPE: Technical Report

PUB.  COUNTRY: Germany Federal Republic

SOURCE: Department of Energy [DEE],  Jun 85,  238p.



The subject of this thesis has been to study the interaction of a metallic cobalt catalyst with zeolite supports and alkali as promoter in the CO hydrogenation reaction. For this purpose molecular sieves of the types of zeolite 4A, chabazite/erionite, ZSM-5, silicalite, mordenite and zeolite Y as well as two silica carriers have been impregnated with aqueous cobalt-nitrate solution and reduced. The obtained catalysts were characterized by CO- and H sub 2 -chemisorption, thermogravimetric analysis, X-ray diffraction and electron microscopy. The catalytic activities of the Co/zeolite-catalysts were determined to be all about 6x10 sup -4 converted CO per reduced Co per second. This value was half an order of magnitude less than those measured for the Co/silica-catalysts. Model calculations showed that a possible electrostatic field effect inside zeolite pores should be rather small. The hydrocarbon composition of the Fischer-Tropsch products followed the Schulz-Flory distribution.  Chain growth, olefin-to-paraffin ratio and CO sub 2 -selectivity grew in the order ZSM-5 < chabazite/erionite < mordenite < zeolite Y < zeolite 4A < silicalite and they correlated best with the basicity of the carriers  increasing in the same order. Experiments with Co/silica as well as with a Co-foil showed that alkali (Na, K) lowers the specific CO-hydrogenation activity and acts as an inhibitor for all the other hydrogenation reaction steps. (ERA citation 11:035641)