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Stable catalyst design for the viable activation of methane to syngas, hydrogen, and chemicals

Problem statement

Methane and light alkanes are surplus species and by-products with relatively poor economic interest. Our goal is to activate C–H σ-bond to produce hydrogen, olefins, carbon monoxide, and carbon nanofibers, following different process strategies such as oxidative coupling (for olefins), CO2 dry reforming (for syngas), cracking or catalytic decomposition (for hydrogen-free of COx and sequestrated carbon nanotubes/nanofibers), cracking/co-cracking with CO or methanol. We work on developing, synthesizing, characterizing, and testing innovative catalysts with a twist of reaction engineering concepts, looking at multi-scale implications.

We delve into the mechanistic insights of a series of in-house synthesized metal-supported heterogeneous catalysts by combining them with dynamic reactors and ab initio calculations. We explore catalysts with promoted lifetime, activity, selectivity, and heat exchange.

We investigate novel reactor designs grounded on forced dynamic (operando) fluidized-bed reactors at high pressures to amplify the kinetic information and hydrogen.

Goals

  • Develop a microkinetic-based modeling framework to analyze the catalyst performance
  • Scale the technical catalyst for its application in demanding exothermic (oxidative coupling of methane using SiC and spray drying) or fluidized-bed (catalytic decomposition of methane) conditions
  • Develop new catalytic concepts based on Ni-alloys (Ni-Fe, -Co, -Zn…)
  • Improve the catalyst structure-function correlations using in-situ, operando, and dynamic techniques and reactors
CHA2023

Related People

Xueqin Bai (Bruce)

Related Publications

Highly Efficient and Stable Methane Dry Reforming Enabled by a Single-Site Cationic Ni Catalyst

by Cheng, Yao, Ou, Hu, Zheng, Li, Morlanes, Cerrillo, Castaño, Gascon, Han
J. Am. Chem. Soc. Year: 2023 DOI: https://doi.org/10.1021/jacs.3c04581

Abstract

Zeolite-supported nickel (Ni) catalysts have been extensively studied for the dry reforming of methane (DRM). It is generally believed that prior to or during the reaction, Ni is reduced to a metallic state to act as the catalytic site. Here, we employed a ligand-protected synthesis method to achieve a high degree of Ni incorporation into the framework of the MFI zeolite. The incorporated Ni species retained their cationic nature during the DRM reaction carried out at 600 °C, exhibiting higher apparent catalytic activity and significantly greater catalytic stability in comparison to supported metallic Ni particles at the same loading. From theoretical and experimental evidence, we conclude that the incorporation of Ni into the zeolite framework leads to the formation of metal–oxygen (Niδ+–O(2−ξ)–) pairs, which serve as catalytic active sites, promoting the dissociation of C–H bonds in CH4 through a mechanism distinct from that of metallic Ni. The conversion of CH4 on cationic Ni single sites follows the CHx oxidation pathway, which is characterized by the rapid transformation of partial cracking intermediates CHx*, effectively inhibiting coke formation. The presence of the CHx oxidation pathway was experimentally validated by identifying the reaction intermediates. These new mechanistic insights elucidate the exceptional performance of the developed Ni-MFI catalyst and offer guidance for designing more efficient and stable Ni-based DRM catalysts.

Keywords

HCE CHA