TITLE: CO + H Sub 2 Reaction over Nitrogen-Modified Iron Catalysts.  Quarterly Technical Progress Report, January 1-March 31, 1984.

AUTHOR: W. N. Delgass.

INST.  AUTHOR: Purdue Univ., Lafayette, IN.

SPONSOR: Department of Energy, Washington, DC.

LANGUAGE: English

PUB.  TYPE: Technical Report

PUB.  COUNTRY: United States

SOURCE: Department of Energy [DE],  Jul 84,  28p.

ABSTRACT:

We have found that the nitride catalysts lose substantial amounts of nitrogen during the initial minutes of Fischer-Tropsch synthesis. In order to further study the stability of these catalysts, we have concentrated on the decomposition of the nitride in hydrogen. In addition, we have prepared a range of epsilon-Fe/sub x/N (2 < x < 3) phases. The Moessbauer parameters from these phases will aid in the identification and fitting of the transient epsilon phases formed during the carburization of Xi-Fe sub 2 N. Extremely rapid nitrogen loss has been observed from Xi-Fe sub 2 N in H sub 2 at 523 K both in constant velocity Moessbauer and in transient mass spectrometer experiments. In order to study the phase change from Xi-Fe sub 2 N to alpha -Fe in more detail, the hydrogenation temperature was decreased to 473 K and intermediate samples were quenched in liquid nitrogen to lock in the phase distribution for subsequent Moessbauer study. The spectra show complete conversion to alpha -Fe at or before 21 minutes at 473 K. The intermediate samples show evidence of an extremely sharp gradient; only a very small amount of gamma ' or epsilon phase is observed. Thus, a moving front model of the phase transformation appears to be appropriate. Mass spectroscopy of the hydrogenation of Xi-Fe sub 2 N at 523 K showed similar behavior to that of both the gamma ' and epsilon phases, in which an active surface species and a slowly activating one were observed. The H sub 2 was replaced by D sub 2 in this experiment in order to observe partially hydrogenated surface species in the initial spike of ammonia. All NH/sub x/D/sub y/ (x + y = 3) species were observed in this spike, indicating extremely rapid surface H/D exchange with gaseous ammonia. The fragmentation pattern of NH sub 3 in the mass spectrometer was also determined and will be used to calculate initial NH/sub x/ surface contributions. 23 references, 3 figures, 3 tables. (ERA citation 09:035261)

REPORT  NUMBER: DOE/PC/50804-6

CONTRACT  NUMBER: FG22-82PC50804