TITLE: Synthesis of Low Molecular Weight Olefins over Coprecipitated Iron-Manganese Catalysts. Volume 8. Final Report.

AUTHOR: W. H. Wiser.

INST.  AUTHOR: Utah Univ., Salt Lake City. Dept. of Fuels Engieering.

SPONSOR: Department of Energy, Washington, DC.

LANGUAGE: English

PUB.  TYPE: Technical Report

PUB.  COUNTRY: United States

SOURCE: Department of Energy [DE],  15 Jun 85,  176p.

NTIS ORDER NO.: DE85014173/INW

ABSTRACT:

The synthesis of low molecular weight olefins (C sub 2 -C sub 4 ) from hydrogen and carbon monoxide has been investigated over unsupported iron-manganese catalysts. Nine iron-manganese catalysts with different atomic ratios were prepared by coprecipitation of Mn/Fe iron and manganese nitrates. Atomic absorption spectroscopy was used to determine the catalyst compositions. The catalysts were evaluated in a conventional bench-scale fixed bed reactor system. A period of 12 hours was generally required to stabilize the activity and selectivity of the iron-manganese catalysts at the operating conditions investigated: 473 to 483 K temperature, 1465 kPa pressure, 2/1:H sub 2 /CO ratio, and 1.08 cm exp 3 g exp -1 s exp -1 reactant gas space velocity. No evidence of catalyst deactivation was detected during the deactivation experiments up to forty hours on stream. A catalyst reduction study with these iron-manganese catalysts was carried out in a thermogravimetric analysis system. A reduction in flowing hydrogen at 673 K and at the ambient pressure for 8 hours was found to be sufficient to activate the catalyst for the carbon monoxide hydrogenation reaction. The hydrogen pretreatment resulted in a relatively more stable pattern of catalyst activity, higher selectivity for C sub 2 -C sub 4 hydrocarbons and lower total production of carbon dioxide and methane. The experimental results of the carbon monoxide hydrogenation at the standard catalyst evaluation conditions over a series of iron-manganese catalysts indicated that the catalyst activity generally decreased as the manganese concentration of the catalyst increased; however, the C sub 2 -C sub 4 olefin selectivity was significantly enhanced in the presence of a small amount of manganese in the catalyst. 86 refs., 35 figs., 22 tabs. (ERA citation 10:046247)

REPORT  NUMBER: DOE/ET/14700-T1-V.8

CONTRACT  NUMBER: AC22-79ET14700