Enhanced activity and sulfur resistance of Cu- and Fe-modified activated carbon for the reduction of NO by CO from regeneration gas

The reduction of NO by CO was proposed to apply in regeneration gas to remove the NOx from industrial flue gas with activated carbon purification technology. To improve the activity...

Catalytic and Sulfur-Tolerant Performance of Bimetallic Ni–Ru Catalysts on HI Decomposition in the Sulfur-Iodine Cycle for Hydrogen Production

The sulfur-iodine (SI) cycle holds great promise as an alternative large-scale process for converting water into hydrogen without CO2 emissions. A major issue regarding the long-term stability and activity of the catalysts is their poor sulfur deactivation resistance in the HI feeding process. In this work, the effect of Ru addition for enhancing the activity and sulfur resistance of SiO2-supported Ni catalysts in the HI decomposition reaction has been investigated. The presence of H2SO4 molecules in the HI results in severe sulfur deactivation of the Ru-free Ni/SiO2 catalysts by blocking the active sites. However, Ni–Ru/SiO2 catalysts show higher catalytic activity without sulfur-poisoning by 25% and exhibit more superior catalytic performance than the Ru-free catalyst. The addition of Ru to the Ni/SiO2 catalyst promotes the stability and activity of the catalysts. The experimental trends in activity and sulfur tolerance are consistent with the theoretical modeling, with the catalytic activities existing in the order Ni/SiO2 < Ni–Ru/SiO2. The effect of Ru on the improvement in sulfur resistance over Ni-based catalysts is attributed to electronic factors, as evidenced by theory modeling analysis and detailed characterizations.

Effect of N (N=Fe, Co, Ni, Cu, Ce) Loaded on Blast Furnace Slag in Low-temperature NH3-SCR

Using low-value solid waste blast furnace slag as a catalyst carrier, the active component N (N = Fe, Co, Ni, Cu and Ce) was loaded by impregnation method to study its effect on the denitration and sulfur resistance of the Mn-based blast furnace slag catalyst. BET, XRD, XPS, SEM and FT-IR characterization methods were used to analyze the denitration mechanism. The results show that: (1) Mn-Ce/GGBS catalyst has better denitration and sulfur resistance; (2) Mn-Ce/GGBS catalyst has a significant denitration effect when load ratio is 2:1; (3) The catalyst can reduce the poisoning and deactivation of S and prolong the catalyst service life; (4) MnO, MnO2, Mn2O3, CeO2 and Ce2O3 play an important role; (5) The larger the ratio of Mn4+/Mn3+, Ce4+/Ce3+, Oα/Oβ, the stronger the catalyst activity and the better denitration effect, and the introduction of SO2 will increase the acid sites on the catalyst surface and increase the catalyst activity.

Improved Sulfur Resistance of COMMERCIAl V2O5-WO3/TiO2 SCR Catalyst Modified by Ce and Cu

The accumulation of NH4HSO4 leads to the deactivation of commercial V2O5-WO3/TiO2 catalyst (VWTi) in practical application. The commercial catalyst is modified with 0.3 wt. % Ce and 0.05 wt. % Cu (donated as VWCeCuTi), and its sulfur resistance is noticeably improved. After loading 20 wt. % NH4HSO4, the NOx conversion of VWCeCuTi-S remains 40% at 250 °C, higher than that of VWTi-S (25%). Through a series of characterization analyses, it was found that the damaged surface areas and acid sites are the key factors for the deactivation of S-poisoned samples. However, surface-active oxygen and NO adsorption are increased by NH4HSO4 deposition, and the L–H mechanism is promoted over S-poisoned samples. Due to the interaction between V, Ce and Cu, the surface-active oxygen over VWCeCuTi-S is increased, and then NO adsorption is promoted. In addition, VWCeCuTi-S obtains a higher V5+ ratio and a better redox property than VWTi-S, which in turn accelerates the NH3-SCR reaction. More NO adsorption and encouraged reaction contribute to the better sulfur resistance of VWCeCuTi.

Sulfur Poisoning on Rh Nanoparticles but Sulfur Promotion on Its Single-Site Catalyst for Carbonylation

Sulfur poisoning is a challenge for most nanoparticle metal catalysts. A trace amount of sulfur contaminants could result in dramatic catalytic activity reduction or even irreversible deactivation1-5. Therefore, new approaches to enhance the catalyst sulfur-resistance have continuously attracted attention from academia and industry. Herein, a role reversal of sulfur from poison to promotor is presented for an Rh-based heterogeneous catalyst from supported Rh nanoparticles (NPs) to its single-site catalysts (Rh1/AC, AC: activated carbon) in methanol carbonylation, ethylene and acetylene hydrocarboxylic reaction with a feed containing 1000 ppm H2S (S-feed). In situ free-electron laser/time of flight mass spectrometry (In situ FEL/TOF MS) indicated that H2S could be quickly transformed into catalyst-friendly CH3SCH3 and/or CH3SH on the Rh1/AC, which coordinated with the Rh ions and promoted its methanol carbonylation reaction, possessing a lower energy barrier based on DFT calculations. On the contrary, strong adsorption of H2S on the surface of Rh NPs inhibited the reaction of reactants.