Hydrogen production through CO2 sorption-enhanced methane steam reforming: Comparison between different adsorbents

Abstract

A two-dimensional transient model has been developed to describe the catalytic methane reforming (MSR) coupled with simultaneous CO2 removal by different absorbents under non-isothermal, non-isobaric and non-adiabatic operating conditions. The influences of temperature, pressure and steam/carbon (S/C) on enhancement were taken into account. The results showed that the hydrogen mole fraction (dry basis) higher than 94% could be achieved using Li4SiO4, CaO, and HTC as CO2 acceptors at the operating conditions of 550°C and 0.1 MPa. When the reaction temperature varied from 500°C to 600°C, the initial CO2 capture rates were HTC>CaO>Li4SiO4>Li2ZrO3, and the saturation rates HTC>CaO>Li4SiO4>Li2ZrO3. Increasing the reaction temperature would improve the CO2 capture rate and available CO2 capacity. For Li4SiO4, although the adsorbing rate increased as the operating temperature increased, the capacity almost did not change. At 550°C, increasing the working pressure could promote the enhancing factors of Li4SiO4,Li2ZrO3 and HTC. There was an optimal steam/carbon ratio between 2–4.5 such that all CaO, Li4SiO4, HTC and Li2ZrO3 would obtain the biggest enhancement for H2 production at the pre-breakthrough stage.