Sustainable and selective hydrogen production by steam reforming of bio-based ethylene glycol: Design and development of Ni-Cu/mixed metal oxides using M (CeO2, La2O3, ZrO2)-MgO mixed oxides

Hydrogen (H-2) production in a clean and green manner via renewable sources is at present of great interest. Ethylene glycol, a bio-based feedstock, offers a sustainable route for high purity H-2 production. In the current investigation, MgO based mixed metal oxides containing CeO2, La2O3 and ZrO2 were synthesized and used to support 20 wt% Ni-Cu (1:1). The impacts of altering support characteristics on catalytic behavior have been studied and compared in H-2 synthesis via ethylene glycol steam reforming (SR), employing various characterization techniques such as XRD, SEM, EDX, TEM, H-2-TPR, H-2-TPD, TG-DSC and BET. Further, high resolution XPS studies were performed to explore the valence states and effectiveness of surface engineering of the catalysts. Assessment of the efficacy of catalysts was done via several parameters such as reactant conversion, H-2 concentration and long-term stability. All the synthesized materials produced encouraging results with high H-2 yield and conversion under the said operating conditions [T-623 to 773 K; GHSV - 3120 to 6240 h(-1) ; P - 0.1 MPa; S/C - 3 to 7.5 mol/mol]. Amongst the three catalysts, Ni-Cu/La2O3 -MgO and Ni-Cu/CeO2-MgO exhibited superior behavior for high H-2 production. Ni-Cu/La2O3-MgO was better in comparison to Ni-Cu/CeO2-MgO in terms of reactant conversion whereas Ni-Cu/CeO2-MgO showed highest H-2 concentration (98 mol %) and improved stability along with absence of carbon deposition owing to its high mobile oxygen vacancies in its lattice. The highly active cubic CeO2 species and its long-term durability (up to 8 cycles) owing to its exceptional redox property further justified its efficacy. The optimized process showed that at T = 773 K, GHSV = 3120 h(-1), S/C = 4.5 mol/mol for Ni-Cu/La2O3-MgO and Ni-Cu/CeO2-MgO and at T = 773 K, GHSV = 3120 h(-1), S/C = 6 mol/mol and for Ni-Cu/ZrO2-MgO, maximum H-2 concentration was obtained. At the end, reaction pathway followed by the catalysts was proposed. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Hydrogen production via renewable sources using ethylene glycol as a feedstock is of great interest. Mixed metal oxides supported Ni-Cu catalysts showed promising results for high purity H-2 production, with Ni-Cu/CeO2-MgO exhibiting the highest H-2 concentration and stability.