High-temperature steam reforming catalysts

Table 4 Selected best performing catalysts for the middle-, and high-temperature steam reforming of ethanol (SRE) reaction"...

Notably, since high-temperature steam reforming enhances the r-WGSR, which would produce CO, the undesirable poison of fuel cells, low-temperature reforming is preferable. Low temperatures can be achieved over strong acid catalysts, although the strong acid at the same time tends to cause deactivation by coke formation. 

Matsumura Y, Ishibe H. High temperature steam reforming of methanol over Cu/ZnO/ Zr02 catalysts. Appl Catal B Environ 2009 91 (1 —2) 524—32. 

Table 2.29. Selected Best Performing Catalysts for the Middle- and High-Temperature Steam Reforming of Ethanol (SRE) Reaction3...

The steam reformer process involves the reaction of methane and high temperature steam in the presence of a nickel catalyst. The reactions are... 

DME hydrolysis is an equilibrium-limited reaction and is considered as the rate-limiting step of overall DME steam reforming. The equilibrium conversion of hydration of DME is low at low temperatures (e.g. about 20% at 275 °C). However, when methanol formed in the first step is rapidly converted into H2 and CO2 by methanol steam reforming catalysts, high DME conversion is expected. Therefore, enhancement of DME hydrolysis is an important factor to obtain high reforming conversion. 

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]. 

In the example of partial oxidation of methane the highly endothermic reaction of steam reforming of natural gas was combined with the exothermic combustion of methane. Reverse flow operation makes it possible to achieve high temperature in the catalyst bed at a low average difference between outlet and inlet temperatures, thus decreasing the methane consumption for exothermic combustion. Pilot plant tests [32] have demonstrated the feasibility of this concept. 

The coking of steam reforming catalysts is a well recognised problem which has received much attention [3,4,5,6]. At high temperatures coke deposition may result from reactions on the catalyst or in the gas phase [7], although the latter are less common in the steam reforming situation. 

From consideration of the thermodynamics of sulfur chemisorption on ruthenium (ref. 6), the gas phase sulfur activities (llgS/l ) of the lightly and moderately sulfur-poisoned Ru catalysts in equilibrium with the adsorbed sulfur at the process temperature (190 C), were approximately 0.02 and 1 ppb+ respectively. On the basis of these results, the equivalent partial pressure ratio for critical sulfur coverage is about 1 ppb at 490 C. This level is well below that attainable by conventional sulfur removal methods. Thus our result confirms the need for high performance desulfurization technology (ref 3) that can reduce sulfur contaminants in feedstocks to a sufficiently low sulfur level to avoid carbon fouling cf Ru/A Og steam reforming catalysts. 

Carbon formation limited by precious metal steam reforming catalysts, high steam-to-carbon (S/C) ratio (1.3), and high reforming temperature (>725°C)... 

---