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Title: Importance of ammonia pressure in the kinetics of ammonia synthesis over supported Ru

Journal Article · · J. Catal.; (United States)

This study examines the ammonia dependence of the synthesis rate over supported (but unpromoted) ruthenium using data collected with a flow reactor coupled with effluent ammonia determination. Silica gel and ..gamma..-alumina powder were impregnated to Ca. 1.0 to 1.3 wt % ruthenium loading by incipient wetness using an aqueous solution of RuCl/sub 3/ . 3 H/sub 2/O. Following this impregnation, the samples were dried overnight in air at 380 K, and then a portion, 1.5 g in the case of the silica-supported sample and 2.2 g in the case of the alumina-supported sample, was loaded into a flow reactor for hydrogen reduction (at 700K for ca. 50h) and subsequent ammonia synthesis studies at atmospheric pressure (0.1 MPa). This study has yielded ammonia synthesis turnover frequencies and apparent activation energies at constant flow rate that are in good agreement with the results of Ozaki et al. This study has also shown that the rate of ammonia synthesis does indeed exhibit an ammonia dependence in the same range of ammonia pressures studied by Ozaki et al. Apparent activation energies calculated at constant ammonia pressure are greater than those determined at constant flow rate. 6 figures, 1 table. (DP)

Research Organization:
Univ. of Wisconsin, Madison
OSTI ID:
5031295
Journal Information:
J. Catal.; (United States), Vol. 62:1
Country of Publication:
United States
Language:
English