Enhanced Catalytic Oxidation Reactivity over Atomically Dispersed Pt/CeO2 Catalysts by CO Activation.

The elevation of the low-temperature oxidation activity for Pt/CeO2 catalysts is challenging to meet the increasingly stringent requirements for effectively eliminating carbon monoxide (CO) from automobile exhaust. Although reducing activation is a facile strategy for boosting reactivity, past research has mainly concentrated on applying H2 as the reductant, ignoring the reduction capabilities of CO itself, a prevalent component of automobile exhaust. Herein, atomically dispersed Pt/CeO2 was fabricated and activated by CO, which could lower the 90% conversion temperature (T90) by 256 °C and achieve a 20-fold higher CO consumption rate at 200 °C. The activated Pt/CeO2 catalysts showed exceptional catalytic oxidation activity and robust hydrothermal stability under the simulated working conditions for gasoline or diesel exhausts. Characterization results illustrated that the CO activation triggered the formation of a large portion of Pt0 terrace sites, acting as inherent active sites for CO oxidation. Besides, CO activation weakened the Pt-O-Ce bond strength to generate a surface oxygen vacancy (Vo). It served as the oxygen reservoir to store the dissociated oxygen and convert it into active dioxygen intermediates. Conversely, H2 activation failed to stimulate Vo, but triggered a deactivating transformation of the Pt nanocluster into inactive PtxOy in the presence of oxygen. The present work offers coherent insight into the upsurging effect of CO activation on Pt/CeO2, aiming to set up a valuable avenue in elevating the efficiency of eliminating CO, C3H6, and NH3 from automobile exhaust.

Trace SO2 capture within the engineered pore space using a highly stable SnF62--pillared MOF.

Developing reliable solid sorbents for efficient capture and removal of trace sulfur dioxide (SO2) under ambient conditions is critical for industrial desulfurization operations, but poses a great challenge. Herein, we focus on SNFSIX-Cu-TPA, a highly stable fluorinated MOF that utilizes SnF62- as pillars, for effectively capturing SO2 at extremely low pressures. The exceptional affinity of SNFSIX-Cu-TPA towards SO2 over CO2 and N2 was demonstrated through single-component isotherms and corroborated by computational simulations. At 298 K and 0.002 bar, this material displays a remarkable gas uptake of 2.22 mmol g-1. Among various anion fluorinated MOFs, SNFSIX-Cu-TPA shows the highest SO2/MF62- of 1.39 mmol mmol-1 and exhibits a low Qst of 58.81 kJ mol-1. Additionally, SNFSIX-Cu-TPA displays excellent potential for SO2/CO2 separation, as evidenced by its ideal adsorbed solution theory (IAST) selectivity of 148 at a molar fraction of SO2 of 0.01. Dynamic breakthrough curves were obtained to reveal the effective removal of trace SO2 from simulated flue gas (SO2/CO2/N2; v/v/v 0.2/10/89.8) with a high dynamic capacity of up to 1.52 mmol g-1. Furthermore, in situ TGA demonstrated the efficient and reversible capture of 500 ppm SO2 over 20 adsorption-desorption tests. This durable material presents a rare combination of exceptional SO2 capturing performance, good adsorption selectivity, and mild regeneration, thus making it a good candidate for a realistic desulfurization process.

Asymmetric Ru-In atomic pairs promote highly active and stable acetylene hydrochlorination.

Ru single-atom catalysts have great potential to replace toxic mercuric chloride in acetylene hydrochlorination. However, long-term catalytic stability remains a grand challenge due to the aggregation of Ru atoms caused by over-chlorination. Herein, we synthesize an asymmetric Ru-In atomic pair with vinyl chloride monomer yield (>99.5%) and stability (>600 h) at a gas hourly space velocity of 180 h-1, far surpassing those of the Ru single-atom counterparts. A combination of experimental and theoretical techniques reveals that there is a strong d-p orbital interaction between Ru and In atoms, which not only enables the selective adsorption of acetylene and hydrogen chloride at different atomic sites but also optimizes the electron configuration of Ru. As a result, the intrinsic energy barrier for vinyl chloride generation is lowered, and the thermodynamics of the chlorination process at the Ru site is switched from exothermal to endothermal due to the change of orbital couplings. This work provides a strategy to prevent the deactivation and depletion of active Ru centers during acetylene hydrochlorination.

Lattice-Strain Engineering in Ni-Ru Heterostructures for Efficient Acetylene Hydrochlorination toward Vinyl Chloride.

Ru-based catalysts have emerged as promising alternatives to HgCl2 in vinyl chloride monomer (VCM) production by acetylene hydrochlorination. However, poor C2H2 activation and the generation of key intermediates (*CH2═CH) have posed grand challenges for enhanced catalytic performances. Herein, we synthesized a Ni-intercalated Ru heterostructure using a lattice-strain engineering strategy, resulting in the desired electronic and chemical environments. The collaboration of Ni splits the adsorption centers of C2H2 and HCl by weakening the strong steric hindrance, and it also promotes the activation of the linear C≡C configurations. The well-controlled lattice strain enables strong d-d hybridization interactions between Ni and Ru, resulting in an upshift of the d-band center from -3.72 eV (for Ru/C) to -3.49 eV and electronic delocalization. This optimized local Ni-Ru/C structure thus enhances *H adsorption while weakening the energy barrier for generating *CH2═CH intermediates. Furthermore, the energy barrier for VCM formation was simultaneously reduced. Accordingly, the Ni-Ru/C heterostructures achieve improved performance in pilot-scale trials, with a conversion of >99.2% and stability for over 500 h. These performances significantly surpass most reported Ru-based moieties and the traditional Hg catalysts, offering a promising avenue for C2H2 activation in industrial applications.