Cr and CeO2 promoted Ni/SBA-15 framework for hydrogen production by steam reforming of glycerol

Abstract

Ni/SBA-15 meso-structured catalysts modi ed with Chromium and CeO 2 (Ni-Cr-CeO 2 /SBA-15) were utilized to produce hydrogen from glycerol steam reforming (GSR). The catalysts were synthesized by a one-pot hydrothermal process and extensively characterized by analytical techniques such as N 2 adsorption-desorption (BET), H 2 -temperature programmed reduction (H 2 -TPR), powder X-ray diffraction (PXRD), Inductively coupled plasma-optical emission spectrometry (ICP-OES), and Transmission electron microscopy (TEM). Overall, the Ni-based catalysts exhibited higher glycerol conversion − 12Ni-SBA-15-99.9%, 12Ni3CeO 2 -SBA-15-89.4% and 8Ni4Cr3CeO 2 -SBA-15-99.7%. Monometallic 12Ni/SBA-15 performed exceptionally well, while 12Cr/SBA-15 performed poorly with the highest 71.48% CO selectivity. For shortterm GSR reactions, CeO 2 addition to 12Ni/SBA-15 did not have any effect, whereas Cr addition resulted in 32% decrease in H 2 selectivity. The long-term stability studies of 12Ni-SBA-15 showed H 2 selectivity of ~ 64% and ~ 98% glycerol conversion. However, its activity was short-lived. After 20-30hrs, the H 2 selectivity and conversion dropped precipitously to 40%. The doping of mesoporous Ni/SBA-15 with Cr and CeO 2 remarkably enhanced the long-term stability of the catalyst for 12Ni3CeO 2 -SBA-15, and 8Ni4Cr3CeO 2 -SBA-15 catalyst with ~ 58% H 2 selectivity and ~ 100% conversion for the entire 60hrs. Nonetheless, Cr and CeO 2 seem to improve the shelf-life of Ni-SBA-15 via different mechanistic pathways. CeO 2 mitigated Ni poisoning through coke oxidation whereas Cr bolstered the catalyst stability via maintaining a wellde ned pore size and structural integrity of the heterogeneous framework, thereby restricting structural collapse, and hence reducing sintering of the Ni active sites during the long-term 60hrs continuous reaction.

Research Advances of Non-Noble Metal Catalysts for Oxygen Evolution Reaction in Acid

“…Yet, pushing covalency to extremes might induce surface amorphization or undesired structural shifts [118]. Such transitions manifest when the OH-(base)/H 2 O (acid) adsorption pace or the lattice oxygen migration speed cannot counterbalance the surface Vo generation rate, culminating in cation loss [119]. As TM d-O p covalency intensifies, so does the metal dissolution rate, potentially ushering in surface modifications or complete structural disintegration.…”

Role of Mn in the Ni–Mn/SBA-15 Catalyst for Hydrogen Production by Biomass Steam Reforming at Relatively Low Temperature

“…The addition of promoters has the potential to enhance the catalytic activity, improve the metal reducibility, increase the regenerability of spent catalysts, and sustain the resistance to catalyst deactivation. In this aspect, the addition of second metals such as Ca, , Fe, Co, Cu, CeO 2 , , Cr, La, Ce, Sr, Mn, − etc. to Ni-based catalysts has been investigated in many studies.…”