Highly efficient and reusable nanostructured porous Ni/La2O2CO3 tandem catalyst for hydrogen and methane production from subcritical hydrothermal treatment of nitrocellulose

Authors: PARK, JUNG HYUN - University Of Illinois; SCOTT, JOHN - University Of Illinois; RAJAGOPALAN, NANDAKISHORE - University Of Illinois; Sharma, Brajendra - Bk; KIM, JAEMIN - University Of Illinois

Submitted to: Chemical Engineering Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/9/2024
Publication Date: 3/11/2024
Citation: Park, J., Scott, J.W., Rajagopalan, N., Sharma, B.K., Kim, J. 2024. Highly efficient and reusable nanostructured porous Ni/La2O2CO3 tandem catalyst for hydrogen and methane production from subcritical hydrothermal treatment of nitrocellulose. Chemical Engineering Journal. 486:150330. https://doi.org/10.1016/j.cej.2024.150330.
DOI: https://doi.org/10.1016/j.cej.2024.150330

Interpretive Summary: Conversion of organic waste to hydrogen and methane for energy generation is one of the effective sustainable ways to deal with municipal solid waste (MSW). There are various processes with their own merits and demerits. Hydrothermal at lower temperature/pressure offers a promising solution, however efficient production of hydrogen and methane remains a challenge. This work reports the synthesis of a nanostructured catalyst and shows its application to efficiently convert cellulosic sugars to methane production under hydrothermal conditions. The catalytic activity of the new catalyst outperforms the activity of the current most known catalysts such as Raney Nickel under these conditions. The outcome from this work can be applied to carbon dioxide methanation for a variety of waste biomass/biorefinery byproducts for sustainable production of gaseous fuel, which will help improve the economics of biorefineries and thereby help farmers by increasing the value of waste biomass generated on the farms, and also utilization of organic waste present in MSW.

Technical Abstract: Conversion of biowaste to value-added gas products such as hydrogen (H2) and methane (CH4) is one of effective and sustainable strategies in municipal solid waste (MSW) treatment fields. Cost-effective subcritical water conditions offer a promising solution; however, the efficient production of H2 and CH4 still remains a challenge in such conditions. In this report, a synthesized, nanostructured highly porous tandem catalyst, nickel nanoparticle-exsolved lanthanum oxycarbonate (Ni/La2O2CO3), presents its high catalytic efficacy to convert CO2 to CH4 without throughput of H2 gas under subcritical water conditions. The nanostructured tandem catalyst provides catalytically active triple-phase boundaries, which thus exhibits the remarkable CH4 production performance, achieving a 14% carbon yield (versus carbon in nitrocellulose) under 350 degree C and 4.5 MPa reaction conditions. The obtained performance easily overwhelms the activity of the current most known catalysts such as Raney Nickel or Ni/La2O3 in subcritical conditions. The mechanism study using the temperature-dependent X-ray diffraction (XRD)-assisted structure study and the electron paramagnetic resonance (EPR) spectroscopy analysis further elucidated the origin of high catalytic efficacy together with the phase change of the tandem catalyst. This study highlights that the newly designed Ni/La2O2CO3 catalyst can be potentially applied to CO2 methanation for a variety of biomass with important implications for the sustainable production of value-added gases from biowaste.