ABSTRACT
The effect of ammonia in syngas on the performance of two different supported cobalt catalysts (i.e., Co/Al2O3 and Co/SiO2) was investigated during Fischer-Tropsch synthesis using a continuous stirred-tank reactor. In our earlier study21 using a Co/ alumina catalyst, ammonia exhibited a negative effect on CO conversion and a positive effect on selectivity (i.e., lower methane and higher C5+ selectivities). In the current contribution, the effect on a Co/silica catalyst was studied under similar conditions as used previously for Co/alumina, and the addition of 10 ppmw (concentration of ammonia with respect to the syngas feed) of ammonia resulted in significant irreversible deactivation of the catalyst. The addition of ammonia increased methane selectivity and decreased higher hydrocarbon selectivity compared to ammonia-free synthesis conditions for the silica-supported catalysts. During the ammonia exposure, the percentage of deactivation is higher in silica-supported catalysts than the alumina-supported catalyst. Addition of ammonia led to significant losses in BET
14.1 Introduction .................................................................................................. 258 14.2 Experimental ................................................................................................ 259
14.2.1 Catalyst Preparation .......................................................................... 259 14.2.2 Catalyst Characterization .................................................................260
