Design of bimetallic Rh-M catalysts for N2O decomposition: From DFT calculation to experimental study

Progress and challenges in nitrous oxide decomposition and valorization

Nitrous oxide (N2O) decomposition is increasingly acknowledged as a viable strategy for mitigating greenhouse gas emissions and addressing ozone depletion, aligning significantly with the UN's sustainable development goals (SDGs) and carbon neutrality objectives. To enhance efficiency in treatment and explore potential valorization, recent developments have introduced novel N2O reduction catalysts and pathways. Despite these advancements, a comprehensive and comparative review is absent. In this review, we undertake a thorough evaluation of N2O treatment technologies from a holistic perspective. First, we summarize and update the recent progress in thermal decomposition, direct catalytic decomposition (deN2O), and selective catalytic reduction of N2O. The scope extends to the catalytic activity of emerging catalysts, including nanostructured materials and single-atom catalysts. Furthermore, we present a detailed account of the mechanisms and applications of room-temperature techniques characterized by low energy consumption and sustainable merits, including photocatalytic and electrocatalytic N2O reduction. This article also underscores the extensive and effective utilization of N2O resources in chemical synthesis scenarios, providing potential avenues for future resource reuse. This review provides an accessible theoretical foundation and a panoramic vision for practical N2O emission controls.

DFT Study of N2O Adsorption onto the Surface of M-Decorated Graphene Oxide (M = Mg, Cu or Ag)

In order to reduce the harm of nitrous oxide (N₂O) on the environment, it is very important to find an effective way to capture and decompose this nitrous oxide. Based on the density functional theory (DFT), the adsorption mechanism of N₂O on the surfaces of M-decorated (M = Mg, Cu or Ag) graphene oxide (GO) was studied in this paper. The results show that the effects of N₂O adsorbed onto the surfaces of Mg–GO by O-end and Cu–GO by N-end are favorable among all of the adsorption types studied, whose adsorption energies are −1.40 eV and −1.47 eV, respectively. Both adsorption manners belong to chemisorption. For Ag–GO, however, both the adsorption strength and electron transfer with the N₂O molecule are relatively weak, indicating it may not be promising for N₂O removal. Moreover, when Gibbs free energy analyses were applied for the two adsorption types on Mg–GO by O-end and Cu–GO by N-end, it was found that the lowest temperatures required to undergo a chemisorption process are 209 °C and 338 °C, respectively. After being adsorbed onto the surface of Mg–GO by O-end, the N₂O molecule will decompose into an N₂ molecule and an active oxygen atom. Because of containing active oxygen atom, the structure O–Mg–GO has strong oxidizability, and can be reduced to Mg–GO. Therefore, Mg–GO can be used as a catalyst for N₂O adsorption and decomposition. Cu–GO can be used as a candidate material for its strong adsorption to N₂O.

Efficient and controllable alcoholysis of Kraft lignin catalyzed by porous zeolite-supported nickel-copper catalyst

The alcoholysis of Kraft lignin was catalyzed by bimetallic Ni-Cu supported on H-Beta, HZSM-5, MAS-7, MCM-41 and SAPO-11 zeolite materials in isopropanol solvent. Results showed that a higher bio-oil yield of 98.80 wt% and monomer yield of 50.83 wt% without obvious char were achieved at 330 °C for 3 h over Ni-Cu/H-Beta catalyst. Isopropanol was found to be more effective in H₂ generation and facilitated to the hydrodeoxygenation of lignin-derived phenolic compounds. Moreover, the composition of liquid products was also influenced by the acidity and pore structure of catalyst. The superior cycloalkanes yield was produced over Ni-Cu/H-Beta with larger pore size and more acidity. In contrast, a large number of cyclic ketones/alcohols and alkanes were obtained over other zeolites supported catalysts with smaller pore size and less acid content. Besides, the temperature, time and solvent effect on the lignin depolymerization were also researched.