Reactor preferential oxidation

A microchannel reactor for CO preferential oxidation was developed. The reactor was consisted of microchannel patterned stainless steel plates which were coated by R11/AI2O3 catalyst. The reactor completely removed 1% CO contained in the Ha-rich reformed gas and controlled CO outlet concentration less than Ippm at 130 200°C and 50,000h. However, CH4 was produced from 180"C and CO selectivity was about 50%. For high performance of present PrOx reactor, reaction temperature should be carefully and uniformly controlled to reach high CO conversion and selectivity, and low CH4 production. It seems that the present microchaimel reactor is promising as a CO removal reactor for PEMFC systems. 

The main unit is the catalytic primaiy process reactor for gross production, based on the ATR of biodiesel. After the primary step, secondary units for both the CO clean-up process and the simultaneous increase of the concentration are employed the content from the reformated gas can be increased through the water-gas shift (WGS) reaction by converting the CO with steam to CO and H. The high thermal shift (HTS) reactor is operating at 575-625 K followed by a low thermal shift (LTS) reactor operating at 475-535 K (Ruettinger et al., 2003). A preferential oxidation (PROX) step is required to completely remove the CO by oxidation to COj on a noble metal catalyst. The PROX reaction is assumed to take place in an isothermal bed reactor at 425 K after the last shift step (Rosso et al., 2004). 

To further reduce the carbon monoxide, a preferential oxidation reactor or a carbon monoxide selective methanation reactor is used. The term selective oxidation is also used for preferential oxi-... 

As mentioned earlier, reformate from a fuel processor often needs addition processing to reduce the carbon monoxide levels. Researchers at the Stevens Institute of Technology are developing a microscale preferential oxidation (FrOx) reactor to decrease the carbon monoxide level in the reformate stream to below 100 ppm. As part of their research, they used advanced computational fluid dynamic modeling. 

Pfiefer et al. are developing a methanol fuel processor system using steam reforming for a 200 Wg fuel cell based power supply. The researchers are currently working on the methanol reformer reactors, heat exchangers, combustors, and preferential oxidation reactors (Figure 23) for the system. The reactor bodies are either stainless steel or copper. 

Figure 2.60 Integrated reactor/heat exchanger for the preferential oxidation of carbon monoxide developed by Eindhoven University and IMM [89] (source IMM).

Schuessler et al. [85] of XCELLSiS (later BALLARD) presented an integrated methanol fuel processor system based on autothermal reforming, which coupled fuel/water evaporation with exothermic preferential oxidation (PrOx) of carbon monoxide. The reactor technology was based, in contrast to most other approaches, on a sintering technique. 

R 20] The fuel processing system consists of a fuel evaporator, a reformer, a reactor for the preferential oxidation of carbon monoxide and a catalytic burner (Figure 4.48) [95],... 

This system includes several mixing and heat exchange units. A concept for an integrated, microtechnology-based fuel processor was proposed by PNNF [8]. As examples for unit operations which may be included in future integrated systems the same publication mentions reactors for steam reforming and/or partial oxidation, water-gas shift reactors and preferential oxidation reactors for carbon monoxide conversions, heat exchangers, membranes or other separation components. 

Kahlich, M.J., Gasteiger, H.A., and Behm, RJ. Preferential oxidation of CO over Pt/y-AI203 and Au/a-Fe203 Reactor design calculations and experimental results. Journal of New Materials for... 

Ahluwalia, R.K., Zhang, Q., Chmielewski, D.J., Lauzze, K.C., and Inbody, M.A. Performance of CO preferential oxidation reactor with noble-metal catalyst coated on ceramic monolith for onboard fuel processing applications. Catalysis Today, 2005, 99, 271. 

Castaldi, M.J., Boorse, R.S., Roychoudhury, S., Menacherry, P., and Pfefferle, W.C. Lightweight, Compact, Ultra-fast Short Contact Time Preferential Oxidation Reactor for Automotive PEM Fuel Cell Applications, NSF National Meeting (ed. National Science Foundation). San Juan, Puerto Rico National Science Foundation, January 2002. 

For the long-term durability of PEMFC, the acceptable CO concentration appears to be 10-100 ppm. To meet the requirement, three possible reactions can be considered preferential (or selective) oxidation, methanation, and Pd (or Pd alloy) membrane processes. Preferential oxidation (PrOx) of CO can convert CO to CO2, without excessive hydrogen oxidation (to water), to acceptable levels of CO using multi-stage reactors... 

Design of 50 kW integrated fuel processor, which includes reformer, shift reactor, steam generator and preferential oxidation reactor. 

Produced required amount of Catalytica Energy System s autothermal reformer (ATR) catalyst. Produced required amount of NexTech platinum (Pt)/ceria medium-temperature-shift (MTS) catalyst. Obtained Eos Alamos National Eaboratory preferential oxidation (PROX) reactor. 

Los Alamos National Laboratory provided a preferential oxidation reactor suitable for... 

---