Fischer-Tropsch (FT) synthesis is an effective technology to indirectly upgrade the abundant coal, natural gas, and renewable biomass resources into high-value added fine chemicals and fuels [1]. Gasification is the process in which a carbon source (biomass, coal, petcoke and reforming of natural gas) is converted to synthesis gas in the presence of oxygen/air and steam. FT conversion processes are affected by the presence of impurities such as H2S, COS, NH3, HCN, and tars, formed during gasification. Although present in moderate amounts, the impurities can have a significant impact on the downstream cobalt FT catalyst. Among these impurities, sulfur compounds cause an irreversible deactivation of catalysts used for FT. The effects of nitrogen containing compounds are unclear; some of the results reported no effect [2], while some of them reported an immediate effect on catalytic activity [3]. In our previous investigation [3], we studied the effect of ammonia over a Pt-Co/alumina catalyst by varying the ammonia (NH4OH) concentration from 1 to 1200 ppmw. The aim of the present study is to investigate the effect of ammonia (10 ppmv NH3) on various supported (alumina, silica and titania) cobalt catalysts. All the supported cobalt catalysts exhibited a negative effect on CO conversion (Figure 1), but there is a positive effect on product selectivity for alumina and titania supported catalysts. To investigate the reason for the negative effect on product selectivity for the silica supported catalysts, the samples were investigated using standard H2 TPR and EXAFS and XANES spectroscopic techniques. References 1. Khodakov, A.Y.; Chu, W.; Fongarland, P.; Chem. Review, 107 (2007) 1692. 2. Borg, Ø.; Hammer, N.; Enger, B.C.; Myrstad, R.; Lindvag, O.A.; Eri, S.; Skagseth, T.H.; Rytter, E.; J. Catal. 279 (2011) 163. 3. Pendyala, V.R.R.; Gnanamani, M.K.; Jacobs, G.; Ma, W.; Shafer, W.D.; Davis, B.H.; Appl. Catal. A: Gen. 468 (2013) 38.

Fischer-Tropsch synthesis: Effect of ammonia on supported cobalt catalysts

251st National Meeting (2016)

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