Sorption enhanced steam methane reforming is an advanced environmentally friendly process for hydrogen production. The addition of the sorbent leads to in-situ CO2 capture that shifts thermodynamic equilibrium towards high-purity hydrogen and a sequestration-ready CO2 stream, while reformer heat demands are reduced (due to the exothermic carbonation reaction). We are investigating sorption enhanced steam methane reforming process combined with chemical looping, where in addition to the sorbent, the reformer contains another material that serves as an oxygen transfer material (OTM). During the reduction/reforming step, the OTM is reduced by methane into metallic nickel and the reforming reaction proceeds under near autothermal conditions, while in the second step regeneration of the saturated sorbent is driven by exothermic OTM re-oxidation. The key for the successful commercialization is the development of stable sorbents and OTMs that can undergo multiple cycles without deterioration in their performance. Herein, we report results from evaluation of NiO-based OTMs under conventional reforming as well as under chemical looping reforming conditions. The OTMs were prepared via wet impregnation method using commercial supports (SiO2, TiO2, Al2O3, ZrO2, mixed Ce-La-Zr oxide) and one lab-synthesized support (NiAl2O4) all with 40wt% NiO loading. In experiments under conventional reforming conditions (pre-reduced OTMs) NiO/Al2O3 and NiO/ZrO2 were active with loss of activity less than 8% after 10 h on stream. NiO/NiAl2O4 and NiO/Ce-La-ZrO2 demonstrated constant activity with no deactivation. On the other hand, NiO/SiO2 and NiO/TiO2, were found to be inactive under the same conditions. In the second step, the promising materials were tested under chemical looping reforming conditions (without CO2 sorbent). NiO/ZrO2 and NiO/Ce-La-ZrO2 exhibited good activity with more than 80% initial CH4 conversion and a very good stability with less than 2% deactivation after 20 consecutive redox cycles, corresponding to 20 h exposure in CH4/steam.

Evaluation of NiO-based oxygen transfer materials in chemical looping methane reforming

249th National Meeting (2015)

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