Catalytic steam methane reforming enhanced by CO2 capture on CaO based bi-functional compounds

Sorption enhanced steam methane reforming (SE-SMR) was performed to maximize hydrogen production and contemporary remove CO2 from the product stream using bi-functional sorbent-catalyst compounds. Samples were tested at two different scales: micro and laboratory. The CaO amount varied in the CaO-Ca12Al14O33 sorbent system synthesized by wet mixing (CaO content of 100 wt%, 56 wt%, 30 wt%, or 0 wt% and balance of Ca12Al14O33) which were upgraded to bi-functional compounds by impregnation of 3 wt% of Ni. Nitrogen adsorption (BET/BJH), X-Ray Diffraction (XRD), Temperature-Programmed Reduction (TPR) and Scanning and Transmission Electronic Microscopy (SEM and TEM, respectively) analyses were performed to characterize structural and textural properties and reducibility of the bi-functional materials and evaluate their catalytic behavior. A fixed sorbent composition CaO-Ca12Al14O33 (56 wt% of CaO and Ca12Al14O33 balance), was chosen to study the effect of different weight hourly space times (WHST) and CH4 stream compositions in SE-SMR activity. Impregnated mayenite at both micro and laboratory scales showed stable H2 content of almost 74%, with CH4 conversion of 72% similarly to the values reported by the sample containing 30 wt% of CaO in the post-breakthrough.Sample with 30 wt% of CaO showed promisingly behavior, enhancing H2 content up to almost 94.5%. When the sorption enhanced reaction is performed roughly 89% of CH4 conversion is achieved, and after the pre-breakthrough, the catalyst worked at the thermodynamic level. During cycling sorption/regeneration experiments, even if CO2 removal efficiency slightly decreases, CH4 conversion and H2 yield remain stable.