Comparison and Validation of Plug and Boundary Layer Flow Models of Monolithic Reactors: Catalytic Partial Oxidation of Methane on Rh Coated Monoliths

Abstract

Catalytic partial oxidation of methane in short residence time rhodium coated monolithic reactors offers an attractive route for syngas production. The plug flow and boundary layer flow approximations are considered as computationally efficient substitutes for the full Navier-Stokes model of the reactor while including detailed heterogeneous and homogeneous chemistry. The one dimensional plug flow model has trivial computational demands but only a limited range of application. The boundary layer model provides an excellent, computationally manageable substitute for the full Navier-Stokes model over a wide range of operating conditions. Using the 38-step elementary surface reaction mechanism of Deutschmann et al. (2001a) and the full GRI 3.0 mechanism for gas phase oxidation of methane, the boundary layer model can predict the experimental data of Hickman et al. (1993a) and Horn et al. (2007) with high accuracy. Sensitivity analyses with the boundary layer model delineate the complex surface phenomena responsible for the sharp transitions in reactor performance observed experimentally on increasing the feed methane to oxygen ratio. The detrimental influence of gas phase reactions on increasing the pressure to industrial levels (>20 bars) is also clearly demonstrated.

Autothermal reforming of n-hexadecane over Rh catalyst to produce syngas in microchannel reactor using finite element method

“…Researchers have focused on exploring catalytic autothermal reforming through simulations and experiments . Conventional catalysts used in the reforming process are transition active metals, such as nickel, palladium, cobalt, platinum, ruthenium, and rhodium . Catalyst selection depends on reforming technology, hydrogen production, and probability of avoiding coke formulation.…”

“…Nickel, platinum, and ruthenium have less resistance to coke formulation than rhodium . Under high‐temperature conditions, rhodium shows high resistance to catalyst deactivation and hence produces considerable hydrogen and provides high fuel conversion …”

“…[11][12][13][14][15][16] Conventional catalysts used in the reforming process are transition active metals, such as nickel, 17,18 palladium, 19 cobalt, 20 platinum, 19,21,22 ruthenium, 19,20 and rhodium. 19,20,23,24 Catalyst selection depends on reforming technology, hydrogen production, and probability of avoiding coke formulation. Coke deposition on catalyst affects reactor performance.…”

“…19 Under hightemperature conditions, rhodium shows high resistance to catalyst deactivation and hence produces considerable hydrogen and provides high fuel conversion. 20,23 Microchannel reactor technology exhibits an enhanced performance in terms of transport properties, heat and mass transfer, and contact time. Conventional reactors have high residence time, which limits transport properties, heat and mass transfer, catalyst activity, and gas diffusion.…”