General Prox Reactor Performance

The catalyst formulation chosen needs to be selective toward CO oxidation (Eq. 7.1) over water production and methane reactions (Eqs. 7.2 and 7.4), as well as be active at low temperatures where the reverse rate of Equation 7.3 is slow. The formulation will also need to be highly active for Equation 7.1, thus allowing the use of near stoichiometric amounts of 02. Stoichiometric amounts of 02 are desirable to keep the selectivity toward CO conversion high. Any 02 remaining after conversion of CO will react with H2, thus decreasing the effectiveness of the reactor. 

To further illustrate typical Prox performance, results are shown from tests done with an 02/C0 ratio of 1 1 and a reactor space velocity of 440,000 h using a representative shifted reformate from an autothermal methane reformer (CO 500-10,OOOppm 02 1000-20,000ppm H20 = 32% H2 = 32% C02 = 14%  

N2 balance = 20%). The catalyst formulation used for this example was a Pt/ -Al203. This formulation is very common for the examination of a wide window of temperature operation with no observed methanation. 

Since the maximum selectivity occurs for X = 1, which is the stoichiometric amount to oxidize CO to C02, and diminishes from thereon, while simultaneously 

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This section is focused on the catalyst selection for optimal Prox reactor operation. During the discussion, catalyst formulation will generally cover the active metal (Pt, Rh, Cu, etc.) and support (A1203, ZnO, etc.) with promoters (La, Ce, etc.) however, there are instances in which studies done are more focused on the active metal regardless of the support used and is indicated where appropriate. It should be kept in mind that catalyst formulation selection must be done in the context of the desired performance outcome, or avoidance of certain characteristics and reformate mix. 

The U.S. Department of Energy is also investigating the performance of monolithic reactors using the same cell configuration as General Motors. The catalyst used was Selectra PROX I (BASF Catalysts, LLC), which was used to generate a data set that was incorporated into a correlation that enable them to model different staged reactors. They developed an empirical correlation for selectivity toward CO... 

The U.S. Department of Energy is also investigating the performance of monolithic reactors using the same cell configuration as General Motors. The catalyst used was Selectra PROX I (BASF Catalysts, LLC). 

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