Synthesis of Waste Derived CaO Promoted Hydrotalcite Based Catalyst for Sorption Enhanced Steam Reforming of Methane

Abstract

The waste derived CaO promoted Mg-Ni-Al based hydrotalcites hybrid catalyst was produced by co-precipitation and wetness impregnation method. The hybrid material was tested for sorption enhanced steam methane reforming (SESMR) for hydrogen (H2) production. The catalyst samples were characterized using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, Brunauer Emmett Teller (BET), temperature programmed reduction (TPR), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). Various sequences of CaO loadings from 0-15 % into the Mg-Ni-Al based hydrotalcites (MNA HTc) were assessed for SESMR in a fixed bed reactor. The results showed that 10% CaO@MNA exhibited best performance in terms of longer pre-breakthrough period with respect to other sequences. The CH4 conversion, H2 purity, and CO2 production in the absence of CaO was marked at 60%, 55%, and 14% respectively. However, the CH4 conversion and H2 purity improved to 84% and 80%, while CO2 decreased to 3% in the pre-breakthrough period for 10% CaO @ MNA, respectively at 650 ° C and S/C of 2. The hybrid catalyst was also tested at various temperatures from 650- 850 °C to investigate the effect of CaO sorbent. It was found that elevated temperatures >750 °C reduced the carbonation reaction and shifted the technique to SMR. The spent catalyst exhibited negligible carbon formation on the catalyst. The performance of the reported catalyst-sorbent system is encouraging for further regeneration studies for SMR.