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Hydrogen generation in a multi-channel membrane reactor

University of British Columbia

A novel Multi-Channel Membrane Reactor (MCMR) has been developed for the decentralized production of hydrogen via Steam Methane Reforming (SMR). The concept alternates steam reforming gas channels to produce the hydrogen and Methane Catalytic Combustion (MCC) gas channels to provide the heat of reaction. A palladium-silver (Pd/Ag) membrane inside each reforming gas channel shifts the reaction equilibrium, and produces pure hydrogen in a single vessel. A steady-state, non iso-thermal and two-dimensional modeling of the concept was first developed. Sensitivity analyses from the simulations indicated the importance of fast kinetics and thick catalyst coating layers (>80 mm) to avoid limitations from the catalyst. An innovative hot substrate air-spray coating method was developed, and thick layer of catalysts (>240 µm) with good adherence under sonication were obtained. A lab-made Ru MgO-La₂O₃/ y-Al₂O₃ catalyst, with carrier and promoters pre-aged by steam, and coated on pre-oxidized Fecralloy, was found to be suitable for the reforming channel. On the combustion side, commercial Pd y-Al₂O₃ catalysts were successfully coated on stainless steel support. Kinetics parameters were estimated for both reforming and combustion catalysts. A proof-of-concept MCMR was designed and built. Results showed that a methane conversion of 87% was achievable with a pure hydrogen output (99.995%). The reforming experimental results were adequately predicted for a wide range of operating conditions. On the combustion side, the experimental conversions were below the model expectations, likely because of flow distribution and catalyst stability issues. It is shown that the MCMR concept has the potential to give hydrogen yield per reactor volume, and per mass of catalyst, about one order of magnitude higher than for alternate membrane reactor technologies.

Text

2013-01-30

Attribution-ShareAlike 3.0 Unported

http://hdl.handle.net/2429/43522

Chemical and Biological Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-sa/3.0/