(477f) Hydrogen from Natural Gas with No Greenhouse Gas Emissions

Membrane reactor technology holds the promise to circumvent thermodynamic equilibrium limitations by in-situ removal of product species, resulting in improved chemical yields. Recent advances in mixed-conducting oxide-membrane technology present the possibility for a dramatic reduction in the cost and environmental impact of converting petroleum, coal and biomass derived feed stocks to hydrogen and other “value added” hydrocarbons.

We have developed single-step gas to liquid reactors that convert natural gas to C₂₊ products with high yields and no unwanted oxidation byproducts. Conversion of CH₄ to simultaneously produce H₂ on one side of a mixed protonic-electronic conducting SrCe_0.7Zr_0.2Eu_0.1O_3-δ membrane and C₂₊ hydrocarbons (C₂ and aromatics) on the other using a direct non-oxidative methane conversion (DNMC) iron/silica catalyst is demonstrated. Further, by adjusting the operating conditions (e.g., temperature) we can tailor the hydrocarbon products between C₂’s (e.g., C₂H₄) and aromatics (e.g., C₆H₆).

Recently we focused our membrane reactor development on hydrogen production with negligible greenhouse gas emissions, e.g., for the 2CH₄ -> 2H₂ + C₂H₄ reaction all the carbon is tied up in the ethylene co-product. If electricity from today’s grid (0.4 kg CO₂/kWh_e) is used to provide necessary enthalpy this reaction can produce hydrogen at only 0.06 kg CO₂/kg H₂ which is orders of magnitude smaller than either SMR or electrolysis on today’s grid. Moreover, if we take the carbon footprint of ethylene production into consideration this process for hydrogen production is actually carbon negative.