Production of high-purity hydrogen by sorption-enhanced steam reforming process of methanol

Abstract

The sorption-enhanced steam reforming process of methanol (SESRP-MeOH) to produce high-purity H2 was thermodynamically and experimentally studied. Thermodynamic calculations showed that at a CO2 adsorption ratio of 95%, product gas contains 98.36% H2, 32.8 ppm CO under temperature of 130 °C and steam-to-methanol (S/M) molar ratio of 2. However, without adsorption-enhanced, the product gas contains nearly 74.99% H2 with 24.96% CO2 and 525 ppm CO. To verify the thermodynamic calculation results, experiments were performed in a fixed-bed reactor loaded with commercial CuO/ZnO/Al2O3 methanol reforming catalyst and 22% K2CO3-promoted hydrotalcite as CO2 adsorbent. Experimental results showed that 99.61% H2 could be obtained by SESRP-MeOH at reaction temperature of 230 °C and S/M of 2. Under the same CH3OH conversion, the reaction temperature decreased by almost 50 °C and H2 concentration increased of more than 20% using SESRP-MeOH compared with solely steam reforming of methanol. The characterization of the adsorbent and catalyst showed that the adsorbent showed good stability while the catalyst was seriously sintered under the high regeneration temperature of the adsorbent.