Steam reforming of ethanol/gasoline mixtures: Deactivation, regeneration and stable performance

The steam reforming of 85% pure ethanol, 15% gasoline (E85) with and without sulfur was studied over a bimetallic precious metal (Rh/Pt) catalyst deposited on a ceramic monolith. Tests performed at low space velocities (22,000 h−1) confirmed that the catalyst could achieve 100% ethanol and gasoline conversion to equilibrium concentrations of H2, CO, CO2 and CH4 with no signs of deactivation for at least 110 h reforming a sulfur-free E85 fuel. In the presence of 5 ppm sulfur the catalyst maintained 100% ethanol and 100% gasoline conversion for approximately 22 h before rapid deactivation resulted in ethanol conversion values below 21%. TPO analysis established large carbon deposits had formed on the catalyst surface demonstrating that sulfur promoted carbon formation. Following such extensive deactivation full activity was recovered after treating the catalyst with air; however subsequent deactivation occurred more rapidly indicating that some amount of permanent damage had occurred. A process with preemptive regeneration via air treatment was studied and it was found to extend the period of stable activity.

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► Small amounts of sulfur deactivate the catalyst.
► Air regeneration restores activity but subsequent deactivation occurs more rapidly.
► Sulfur is not the sole cause of irreversible deactivation.
► Catalyst chemistry altered with extended periods of time reforming.
► Intermediates of acetaldehyde and ethylene detected during deactivation.