CeO2 based catalysts for elemental mercury capture

The alternative materials to remove Hg 0 from energy utilization sectors is crucial to mercury control in atmosphere. CeO2 based catalysts were prepared by an incipient wetness impregnation (IWI) method. A novel Hg 0 and Hg T temperature-programmed surface reaction (Hg 0 -Hg T -TPSR) was proposed in this study for the investigation of the prepared CeO2 based catalysts with the qualitative and quantitative analyses. The characteristic temperatures, the areas of adsorption region and desorption region, and activation energy with reaction kinetics were investigated to evaluate the performance. It was found that 2wt% Ce catalyst has the best mercury removal performance with the highest Hg 0 removal ability and the lowest Ea. There was also small amount of Hg 2+ detected which indicated the catalytic effect contributed. The results suggested that 2wt% Ce based binary catalysts could be the potential candidates to be investigated in the future study. © 2019 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the scientific committee of ICAE2018 - The 10th International Conference on Applied Energy

Promotion effect and mechanism of the addition of Mo on the enhanced low temperature SCR of NOx by NH3 over MnOx/γ-Al2O3 catalysts

A series of Mn/γ-Al2O3 and MnMo/γ-Al2O3 catalysts were prepared by using Incipient Wetness Impregnation (IWI) method. The catalytic performance tests showed that the Mn3Mo1.25/γ-Al2O3 demonstrated a higher SCR performance (NO conversion of around 96%) at a broad low temperature range (150 to 300°C). The characterization showed that the addition of Mo to the Mn/γ-Al2O3 catalysts could promote the dispersion of MnOx on the surface of γ-Al2O3. The adsorption of NO could form two different species, nitrites and nitrates on the surface of the catalyst. The presence of nitrites is beneficial to low temperature SCR. It is also found that the existence of Mo in the catalyst favours the formation of Mn3+, which plays a critical role in the adsorption of NH3 and therefore improves NH3 adsorption capacity of the MnOx/γ-Al2O3 catalysts. The low temperature SCR of the Mn3Mo1.25/γ-Al2O3 catalyst was found to mainly follow L-H mechanism, but E-R mechanism also plays a role to some extent. Moreover, it is also found that the addition of Mo not only mitigates the deactivation of catalysts, but also broadens the effective temperature range of the SCR catalyst

Synergistic engineering of heteronuclear Ni-Ag dual-atom catalysts for high-efficiency CO2 electroreduction with nearly 100% CO selectivity

Single-atom catalysts (SACs) have emerged as attractive materials for the electrocatalytic carbon dioxide reduction (ECO2R). Dual-atom catalysts (DACs), an extension of SACs, exhibit more compelling functionalities due to the synergistic effects between adjacent metal atoms. However, the rational design, clear coordination mode, and in-depth understanding of heteronuclear dual-atom synergistic mechanisms remain elusive. Herein, a heteronuclear Ni-Ag dual-atom catalyst loaded on defective nitrogen-rich porous carbon, denoted as Ni-Ag/PC-N, was synthesized using cascade pyrolysis. The configuration of Ni-Ag dual-atom sites is confirmed as N3-Ni-Ag-N3. Ni-Ag/PC-N demonstrates a remarkable CO Faradaic efficiency (FECO) exceeding 90% over a broad range of applied potentials, i.e., from −0.7 to −1.3V versus reversible hydrogen electrode (RHE). The peak FECO of 99.2% is observed at −0.8V (vs. RHE). Tafel analysis reveals that the rate-determining step of ECO2R-to-CO is the formation of the *COOH intermediate, and Ni-Ag/PC-N exhibits optimal electrokinetics. In situ FTIR and in situ Raman spectra indicate accelerated production of *COOH intermediates during the ECO2R-to-CO process. Density functional theory (DFT) calculations demonstrate that the coordinated Ni atom lowers the energy barrier of *COOH intermediates formation over the Ni-Ag/PC-N surface, while the adjacent Ag atom mitigates the catalyst poisoning caused by the strong *CO affinity on the Ni atomic site