Nickel catalyst steam gasification

Baker, E. Mudge, L. Brown, M., Steam gasification of biomass with nickel secondary catalysts. Industrial and Engineering Chemistry Research 1987, 26, 1335-1339. 

Garcia, L., Sanchez, J.L., Salvador, M.L., Bilbao, R., and Arauzo J. (1996). Hydrogen-rich Gas from Steam Gasification of Biomass Using Coprecipitated Nickel-alumina Catalysts, Bioenergy 96. The Seventh National Bioenergy Conference, pp. 859-865. 

Nickel-based steam reforming catalysts are very efficient for the decomposition of tars and ammonia in biomass gasification gas. Ceramic candle filters can be applied to remove particles at high temperature. It is proposed to use nickel-activated alumina candle filters for the simultaneous removal of tar, ammonia and particles from biomass gasification gas [12]. 

An obvious improvement in the steam gasification of biomass for synthesis gas production is to operate at higher temperatures and to use catalysts to gasify as much of the char and liquid products as possible. Laboratory-scale experiments have been carried out to examine this possibility (Mitchell et al, 1980). Nickel precipitated on silica alumina (1 1) and a mixture of silica alumina and nickel on alumina were evaluated as catalysts for steam gasification at 750°C and 850°C and atmospheric pressure. The results are summarized in Table 9.6. The function of the silica alumina is to crack the hydrocarbon... 

Minowa, T Ogi, T., Yokoyama, S. (1997) Hydrogen Production from Lignoccllulose Materials by Steam Gasification Using a Reduced Nickel Catalyst. 

The effect of the addition of a potassium promoter to a nickel steam reforming catalyst has been probed in terms of the propensity of the catalyst to resist carbon formation. It has been found that potassium facilitates a reduced accumulation of carbon by decreasing the rate of hydrocarbon decomposition on the catalyst and by increasing the rate of steam gasification of filamentary carbon from the catalyst. The effect of the promoter on the carbon removal reaction is evident in an enhancement of the pre-exponential factor in the rate equation by promotion of water adsorption on the catalyst surface. 

The addition of potassium to a nickel/ -alumina steam reforming catalyst provides resistance to the accumulation of carbonaceous deposits in two ways. First, the alkali reduces the rate of hydrocarbon cracking on the nickel component of the catalyst. Second, the promoter enhances the rate of the steam gasification of carbon on the catalyst. This is accomplished by increasing the surface coverage of water on the catalyst and hence supplementing the pre-exponential component of the gasification rate equation. 

This reaction is hardly directly involved in the steam reforming reactions on nickel catalysts (1), but it operates in regeneration of the catalyst. For H20/C Hm > ca. 10, there is affinity for gasification of carbon via reaction (2) depending on pressure. 

Newly formed carbon may be removed by steaming (600-700°C) [381] according to Equation (5.13) which shows potential for gasification at a H20/H2=10, which is sufficient to keep the nickel catalyst in a reduced state (refer to Chapter 4). In practice fresh whisker carbon can be removed by simply increasing the steam-to-carbon ratio. 

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