Sulfate residuals on Ru catalysts switch CO reduction from methanation to reverse water-gas shift reaction.

Efficient heterogeneous catalyst design primarily focuses on engineering the active sites or supports, often neglecting the impact of trace impurities on catalytic performance. Herein, we demonstrate that even trace amounts of sulfate (SO) residuals on Ru/TiO can totally change the CO reduction from methanation to reverse-water gas shift (RWGS) reaction under atmospheric pressure. We reveal that air annealing causes the trace amount of SO to migrate from TiO to Ru/TiO interface, leading to the significant changes in product selectivity from CH to CO.

Effects of surface fluoride modification on TiO for the photocatalytic oxidation of toluene.

In the present study, we investigated the influence of surface fluorine (F) on TiO for the photocatalytic oxidation (PCO) of toluene. TiO modified with different F content was prepared and tested. It was found that with the increasing of F content, the toluene conversion rate first increased and then decreased.

Effects of freeze-thaw on bank soil mechanical properties and bank stability.

Riverbank instability in the seasonally frozen zone is primarily caused by freeze-thaw erosion. Using the triaxial freeze-thaw test on the bank of Shisifenzi Bend in the Yellow River section of Inner Mongolia, we investigated the changes in the mechanical properties of the soil at different freezing temperatures and freeze-thaw times, and analyzed the bank's stability before and after freezing based on the finite element strength reduction method. The results showed that the elastic modulus, cohesion, internal friction angle and shear strength of the soil tended to decrease with the increase in the number of freeze-thaw cycles and the decrease in freezing temperature.

Synergically regulated silver species and surface oxygen on manganese oxide for promoted activity of formaldehyde oxidation.

Formaldehyde (HCHO) is a common indoor pollutant that is detrimental to human health. Its efficient removal has become an urgent demand to reduce the public health risk. In this work, Ag-MnO-based catalysts were prepared and activated under different atmosphere (i.

Incorporation of Epoxy Carbon onto CeO-Supported Pt to Tackle the CO Self-Poisoning Issue.

The catalytic oxidation of carbon monoxide (CO) under ambient conditions plays a crucial role in the abatement of indoor CO, which poses risks to human health. Despite the notable activity exhibited by Pt-based catalysts in CO oxidation, their efficacy is usually diminished by the CO self-poisoning issue. In this work, three different Pt/CeO-based catalysts, which have distinct coordinative environments of Pt but an identical Pt/CeO substrate structure, were synthesized by activating the catalyst with CO using different temperatures and durations.

Enhancing oxidation reaction over Pt-MnO catalyst by activation of surface oxygen.

Formaldehyde (HCHO) and carbon monoxide (CO) are both common air pollutants and hazardous to human body. It is imperative to develop the catalyst that is able to efficiently remove these pollutants. In this work, we activated Pt-MnO under different conditions for highly active oxidation of HCHO and CO, and the catalyst activated under CO displayed superior performance.

Tuning hydrogenation chemistry of Pd-based heterogeneous catalysts by introducing homogeneous-like ligands.

Noble metals have been extensively employed in a variety of hydrotreating catalyst systems for their featured functionality of hydrogen activation but may also bring side reactions such as undesired deep hydrogenation. It is crucial to develop a viable approach to selectively inhibit side reactions while preserving beneficial functionalities. Herein, we present modifying Pd with alkenyl-type ligands that forms homogeneous-like Pd-alkene metallacycle structure on the heterogeneous Pd catalyst to achieve the selective hydrogenolysis and hydrogenation.

Effect of different reduction methods on Pd/AlO for o-xylene oxidation at low temperature.

Pd/AlO was pretreated by CO, H and NaBH reduction, respectively. The reduced catalysts were tested for o-xylene oxidation and characterized by power X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and temperature-programmed decomposition of palladium hydride (TPDH). The characterizations indicate the pretreatments lead to distinct Pd particle sizes and amount of surface activated oxygen species, which are responsible for the catalytic performance.

Electronic Modification by Transitional Metal Dopants to Tune the Oxidation Activity of Pt-CeO-Based Catalysts.

While utilization of transitional metals as a promoter has been extensively studied to enhance the activity of Pt-based catalysts for the oxidation of formaldehyde (HCHO), there is still a lack of well elucidated property-function relationship for the rational selection of a promoter in catalyst design. Herein, we modified a Pt/CeO catalyst with two transitional metal dopants (i.e.

Using Amphiphilic Polymer Micelles as the Templates of Antisolvent Crystallization to Produce Drug Nanocrystals.

Biocompatible and biodegradable amphiphilic polymeric micelles (PLA-CMCS-g-OA) were prepared by surface grafting of oleic acid and polylactic acid onto carboxymethyl chitosan and were used as templates for the crystallization of camptothecin. The camptothecin (CPT) nanocrystals prepared by the novel micelle-templated antisolvent crystallization (mt-ASC) method demonstrated higher crystallinity, narrower particle size distribution, and slower release characteristic than those prepared by conventional antisolvent crystallization (c-ASC) using a high initial concentration and fast addition rate. In particular, the CPT release behavior of mt-ASC products in phosphate buffer solutions presented a pH-responsive characteristic with the increasing release rate of CPT under lower pH conditions.

Tuning Metal-Support Interaction of Pt-CeO Catalysts for Enhanced Oxidation Reactivity.

Metal-support interaction (MSI) has been widely recognized to be playing a pivotal role in regulating the catalytic activity of various reactions. In this work, the degree of MSI between Pt and CeO support was finely tuned by adjusting the activation condition, and the obtained catalysts were tested for the oxidative abatement of CO and HCHO under ambient conditions. The characterization of catalysts shows that activation of strongly interacting Pt-CeO at higher temperatures by H leads to a weaker MSI with increased electron density of Pt, and this modification of local electronic properties is demonstrated to result in enhanced O adsorption/activation to prevent the CO self-poisoning effect, while it abates the activity of CO adsorption/activation and oxidation of adsorbed CO.

Elucidating the Active Site and the Role of Alkali Metals in Selective Hydrodeoxygenation of Phenols over Iron-Carbide-based Catalyst.

Iron-carbide-based catalysts have been explored in the selective hydrodeoxygenation (HDO) of phenol, aiming at elucidating the role of active site and alkali metal. Complementary characterization such as X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and scanning transmission electron microscopy coupled with electron energy loss spectroscopy, together with catalytic evaluations revealed a rapid structural reconstruction of iron carbide (Fe C) catalysts, leading to a stable defective graphene-covered metallic Fe active phase (G@Fe) under reaction conditions. Further studies using different alkali metals (i.

Surface engineering of earth-abundant Fe catalysts for selective hydrodeoxygenation of phenolics in liquid phase.

Development of inexpensive sulfur-free catalysts for selective hydrogenolysis of the C-O bond in phenolics (, selective removal of oxygen without aromatic ring saturation) under liquid-phase conditions is highly challenging. Here, we report an efficient approach to engineer earth-abundant Fe catalysts with a graphene overlayer and alkali metal (, Cs), which produces arenes with 100% selectivity from liquid-phase hydrodeoxygenation (HDO) of phenolics with high durability. In particular, we report that a thin (a few layers) surface graphene overlayer can be engineered on metallic Fe particles (G@Fe) by a controlled surface reaction of a carbonaceous compound, which prevents the iron surface from oxidation by hydroxyls or water produced during HDO reaction.

Heterogeneous Reaction of SO on Manganese Oxides: the Effect of Crystal Structure and Relative Humidity.

Manganese oxides from anthropogenic sources can promote the formation of sulfate through catalytic oxidation of SO. In this study, the kinetics of SO reactions on MnO with different morphologies (α, β, γ and δ) was investigated using flow tube reactor and in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). Under dry conditions, the reactivity towards SO uptake was highest on δ-MnO but lowest on β-MnO, with a geometric uptake coefficient (γ) of (2.

Effect of Support on the Activity of Ag-based Catalysts for Formaldehyde Oxidation.

Ag-based catalysts with different supports (TiO2, Al2O3 and CeO2) were prepared by impregnation method and subsequently tested for the catalytic oxidation of formaldehyde (HCHO) at low temperature. The Ag/TiO2 catalyst showed the distinctive catalytic performance, achieving the complete HCHO conversion at around 95 °C. In contrast, the Ag/Al2O3 and Ag/CeO2 catalysts displayed much lower activity and the 100% conversion was reached at 110 °C and higher than 125 °C, respectively.

Effects of particle composition and environmental parameters on catalytic hydrodechlorination of trichloroethylene by nanoscale bimetallic Ni-Fe.

Catalytic nickel was successfully incorporated into nanoscale iron to enhance its dechlorination efficiency for trichloroethylene (TCE), one of the most commonly detected chlorinated organic compounds in groundwater. Ethane was the predominant product. The greatest dechlorination efficiency was achieved at 22 molar percent of nickel.