TITLE: Study of Fischer-Tropsch Model Compounds Reacting over ZSM-5.

AUTHOR: M. G. Riley.

INST.  AUTHOR: Texas A and M Univ., College Station.

SPONSOR: Department of Energy, Washington, DC.


PUB.  TYPE: Technical Report

PUB.  COUNTRY: United States

SOURCE: Department of Energy [DE],  Aug 84,  94p.


The decomposition of three Fischer-Tropsch model compounds (1-decanol, decanal, and n-heptane) over ZSM-5 catalysts ion exchanged with nickel, zinc, and hydrogen was studied. The mechanisms of decomposition and the reaction kinetics of the model compounds were investigated as well as how exchanging the ZSM-5 with different cations affected the mechanisms, kinetics, and product distribution. The mechanism for 1-decanol decomposition was found to be formation of di-n-decyl ether, which then dehydrated to form 1-decene. Decanal was seen to decompose by three different mecanisms: Aldol condensation, cleavage of CO to form n-nonane, and reduction to 1-decanol. Heptane was seen to follow classical carbonium ion chemistry. First order rate constants and activation energies were calculated for n-heptane/Ni-ZSM-5, 1-decanol/Ni-ZSM-5, 1-decanol/H-ZSM-5, decanal/Ni-ZSM-5, and decanal/H-ZSM-5. The activation energies for decomposition were found to be 21 +- 4 Kcal/gmole for 1-decanol to 1-decene; 32 +- 3 Kcal/gmole for n-heptane; and 15 +- 3 Kcal/gmole on Ni-ZSM-5 and 21 +- 1 Kcal/gmole on H-ZSM-5 for decanal decomposing to n-nonane and CO. H-ZSM-5 was determined to be the most active catalyst of the three tested for decomposition of oxygenates. N-ZSM-5 was the most effective catalyst in the cracking of n-heptane. Due to its superior ability to decompose oxygenates, H-ZSM-5 appears to be the best choice for a Fischer-Tropsch liquid up-grading catalyst. For Fischer-Tropsch liquids with high linear alkane contents a small amount of nickel or other dehydrogenation catalyst added to the H-ZSM-5 would probably prove beneficial. 26 references, 12 figures, 8 tables. (ERA citation 09:039816)