A bi-functional Co-CaO-Ca12Al14O33 catalyst for sorption-enhanced steam reforming of glycerol to high-purity hydrogen

Sorption enhanced steam reforming of glycerol (SESRG) enables the production of high-purity hydrogen from the by-product of biodiesel manufacture. To this end, highly stable catalysts and CO2 sorbents are desired to overcome the performance degradation at high temperatures. Herein, a hi-functional catalyst, Co-CaO-Ca12Al14O33, is proposed to couple CO2 sorption and catalytic reforming of glycerol on nanoscale. The catalyst was derived from a Co-Ca-Al hydrotalcite-like (HTl) material to achieve homogeneous mixing of Co, CaO and Ca12Al14O33 as a spacer to prevent CaO sintering. At Ca/Al of 2.8, the highest catalytic activity and sorption capability were reached. Over the optimized catalyst, high-purity H-2 of 96.4% was produced at 525 degrees C through SESRG during the pre-breakthrough stage. High stability of the hi-functional catalyst was demonstrated by a cyclic SESRG-calcination operation up to 50 times. The role of Ca12Al14O33 as spacer of CaO was proved by XRD and TEM-EDS analysis. In addition, it was found that Ca3CO2O6, which is formed during the calcination stage and is reduced during the SESRG to release Co catalysts, may act as a dynamic reservoir of Co catalysts to prevent Co from sintering, leading to an excellent SESRG activity and stability. (C) 2015 Elsevier B.V. All rights reserved.