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By grafting of TaMe 5 (1) on the surface of silica partially dehydroxylated at 500 °C (silica 500 ), a mixture of (SiO)TaMe 4 (2a; major, 65 ± 5%) and (SiO) 2 TaMe 3 (2b; minor, 35 ± 5%) was produced, which has been characterized by microanalysis, IR, and SS NMR ( 1 H, 13 C, 1 H− 13 C HETCOR, proton double and triple quantum). After grafting, these surface organometallic compounds are more stable than the precursor TaMe 5 . Treatment of 2a,b with water and H 2 resulted in the formation of methane in amount of 3.6 ± 0.2 and 3.4 ± 0.2 mol/grafted Ta, respectively. 2a,b react with H 2 (800 mbar) to form (SiO) 2 TaH. After (SiO) 2 TaH was heated to 500 °C under hydrogen or vacuum, [(SiO) 3 Ta][SiH] was produced, and the structure was confirmed by IR, NMR, and EXAFS. Considering the difficulty of the previous preparation method, these syntheses represent a facile and convenient way to prepare tantalum surface species (SiO) 2 TaH and (SiO) 3 Ta via the intermediate of the new surface organometallic precursors: (SiO)TaMe 4 /(SiO) 2 TaMe 3 . ( SiO) 2 TaH and (SiO) 3 Ta exhibit equal reactivities in alkane metathesis and ethylene polymerization in comparison to those in previous reports.

The effect of water on the performance of potassium-promoted precipitated iron catalyst was investigated during Fischer-Tropsch synthesis (FTS) using a continuously stirred tank reactor (CSTR) at two different reaction temperatures. Water was added in such a manner as to replace an equivalent amount of inert gas so that all other reaction conditions (e.g., reactant partial pressure, space velocity) remained the same before, during, and after water addition. The externally added water had a positive effect on CO conversion at 270°C whereas, for the reaction carried out at 230°C, the added water decreased CO conversion and deactivated the catalyst. From these findings, the addition of water at 230°C oxidized the catalyst, transforming the iron carbide to the Fe 3 O 4 phase. When the reaction was carried out at 270°C, severe oxidization did not take place and a carbide phase was retained. The loss in activity and the rate of deactivation were more pronounced at 230°C compared to the 270°C condition for the same catalyst. Mössbauer spectroscopic measurements revealed that for the reaction carried out at 230°C, the catalyst had 85% of the iron present as Fe 3 O 4 and the remaining as Hägg carbide (v-Fe 5 C 2 ), whereas at the higher temperature reaction condition the catalyst had about 66% of the iron present as e 9-Fe 2.2 C, with the remaining as Fe 3 O 4 . These findings were also supported by XANES analysis, where a high white line intensity was observed for the sealed used catalyst sample for the low temperature reaction condition, indicating a higher extent of oxidation. A low white line intensity was recorded for the used sample for the high temperature reaction condition, indicative of a higher extent of reduction.

The successful adaptation of conventional cobalt and iron-based Fischer-Tropsch synthesis catalysts for use in converting biomass-derived syngas hinges in part on understanding their susceptibility to byproducts produced during the biomass gasification process. With the possibility that oil production will peak in the near future, and due to concerns in maintaining energy security, the conversion of biomass-derived syngas and syngas derived from coal/biomass blends to Fischer-Tropsch synthesis products to liquid fuels may provide a sustainable path forward, especially considering if carbon sequestration can be successfully demonstrated.However, one current drawback is that it is unknown whether conventional catalysts based on iron and cobalt will be suitable without proper development because, while ash, sulfur compounds, traces of metals, halide compounds, and nitrogen-containing chemicals will likely be lower in concentration in syngas derived from mixtures of coal and biomass (i.e., using an entrained-flow oxygen-blown gasifier) than solely from coal, other byproducts may be present in higher concentrations. The current project examines the impact of a number of potential byproducts of concern from the gasification of biomass process, including compounds containing alkali chemicals like the chlorides of sodium and potassium.In the second year, researchers from the University of Kentucky Center for Applied Energy Research (UK-CAER) continued the project by evaluating the sensitivity of a commercial iron-chromia high temperature water-gas shift catalyst (WGS) to a number of different compounds, including KHCO 3 , NaHCO 3 , HCl, HBr, HF, H 2 S, NH 3 , and a combination of H 2 S and NH 3 . Cobalt and iron-based Fischer-Tropsch synthesis (FT) catalysts were also subjected to a number of the same compounds in order to evaluate their sensitivities.

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