Cu/ZrO2 Catalyst Modified with Y2O3 for Effective and Stable Dehydration of Glycerol to Acetol.

Glycerol is a main by-product of biodiesel production, and its further processing is essential for the biorefinery. In this paper, a highly active and stable catalyst for the catalytic dehydration of glycerol to acetol is obtained by modifying a Cu-Zr (ZrO2 supported Cu) catalyst with Y2O3 using a co-precipitation method. It is found that the addition of Y2O3 effectively enhances the catalytic performance of Cu-Zr. Cu-Zr reaches the highest selectivity (82.4%) to acetol at 24 h. However, the selectivity decreases to 70.1% at 36 h. The conversion also decreases from 99.2 to 91.1%. Cu-Zr-Y exhibits very high activity and very good stability. During a 250 h reaction, no deactivation is observed, and the conversion and selectivity remains ~100% and ~85%, respectively. The catalysts are characterized by XRD, TEM, H2-TPR, and NH3-TPD. The results reveal that Y2O3 not only improves the dispersion of Cu and the acidity of the catalyst but also restrains the agglomeration of Cu particles and assists retaining the main structure of support under reaction conditions. The high dispersion, high acidity content, and stable structure contributes to the excellent catalytic performance of Cu-Zr-Y.

Enhancing electronic metal support interaction (EMSI) over Pt/TiO2 for efficient catalytic wet air oxidation of phenol in wastewater.

Phenol is one of the major hazardous organic compounds in industrial wastewater. In this work, a highly active Pt/TiO2 catalyst for catalytic wet air oxidation (CWAO) of phenol was obtained by supporting pre-synthesized Pt on TiO2. During the followed hydrogen reduction, strong hydrogen spillover occurred without the migration of TiO2 onto Pt. The reduced support then enhanced the electron transfer from TiO2 to Pt, increasing the percentage of partially negative Pt (Ptδ-), which has been confirmed by XPS. The strong EMSI made the obtained catalyst far more active than Pt/TiO2 prepared by impregnation method. The electron-enriched Pt/TiO2 achieved total organic carbon (TOC) conversion of 88.8% and TOF 149 h-1 at 100 °C and 2 MPa O2, while conventional Pt/TiO2 gave TOC conversion of 39.5% and TOF 41 h-1 for CWAO of phenol. Our work indicates that the enhancement of EMSI between metal and support can be an effective approach to develop highly active catalysts for phenol treatment.

Effect of Metal Precursors on the Performance of Pt/SAPO-11 Catalysts for n-Dodecane Hydroisomerization.

Pt(NH3)4(NO3)2, Pt(NH3)4(Ac)2, (NH4)2PtCl4, and H2PtCl6 were used to prepare Pt/SAPO-11 catalysts to investigate the effect of Pt precursors on the hydroisomerization of n-dodecane. The catalyst derived from Pt(NH3)4(NO3)2 displays the best hydroisomerization activity and selectivity among these precursors. The hydroisomerization conversion of n-dodecane is affected by the platinum particle size, platinum dispersion, the location of platinum, and the valence state of platinum. The selectivity of n-dodecane is determined by the number of Brønsted acid sites and Pt crystal planes. These conclusions are verified by combining transmission electron microscopy, high-resolution transmission electron microscopy, hydrogen temperature programmed reduction, NH3-temperature programmed desorption, and Py-IR studies. The catalyst prepared with Pt(NH3)4(NO3)2 as the precursor exhibits the smallest platinum particle size and the highest platinum dispersion. Most of the platinum particles are supported on the external surface of SAPO-11 with the Pt(111) crystal face. Such a catalyst also possesses a suitable number of Brønsted acid sites and then displays the best catalytic performance. Obviously, the use of various precursors for the Pt-based catalyst can significantly affect the performance of Pt/SAPO-11 for the hydroisomerization of n-dodecane.

The effect of weak acid anions on the selective catalytic wet air oxidation of aqueous ammonia to nitrogen.

In this work, the effect of weak acid anions on the ammonia removal has been extensively studied for the process of selective catalytic wet air oxidation (CWAO) of ammonia to nitrogen. It is found that the presence of weak acid anions can effectively enhance the ammonia conversion and selectivity towards nitrogen. The combination between the weak acid anions and H+ to produce weak acid molecules is responsible for such enhancement. Firstly, the H+ consumption of weak acid anions can increase the NH3 concentration and thus the reactivity of ammonia oxidation, due to the shift to NH3 on the equilibrium of NH4+/NH3. Secondly, the competition combination with H+ between the weak acid anions and NO2- can increase the concentration of NO2- and thus boosts the disproportionation reaction between NH4+ and NO2- to produce nitrogen.

Ultrafine Nanoparticle-Supported Ru Nanoclusters with Ultrahigh Catalytic Activity.

The design of an ideal heterogeneous catalyst for hydrogenation reaction is to impart the catalyst with synergetic surface sites active cooperatively toward different reaction species. Herein a new strategy is presented for the creation of such a catalyst with dual active sites by decorating metal and metal oxide nanoparticles with ultrafine nanoclusters at atomic level. This strategy is exemplified by the design and synthesis of Ru nanoclusters supported on Ni/NiO nanoparticles. This Ru-nanocluster/Ni/NiO-nanoparticle catalyst is shown to exhibit ultrahigh catalytic activity for benzene hydrogenation reaction, which is 55 times higher than Ru-Ni alloy or Ru on Ni catalysts. The nanoclusters-on-nanoparticles are characterized by high-resolution transmission electron microscope, Cs-corrected high angle annular dark field-scanning transmission electron microscopy, elemental mapping, high-sensitivity low-energy ion scattering, and X-ray absorption spectra. The atomic-scale nanocluster-nanoparticle structural characteristics constitute the basis for creating the catalytic synergy of the surface sites, where Ru provides hydrogen adsorption and dissociation site, Ni acts as a "bridge" for transferring H species to benzene adsorbed and activated at NiO site, which has significant implications to multifunctional nanocatalysts design for wide ranges of catalytic reactions.

Effect of calcination temperature and pretreatment with reaction gas on properties of Co/γ-Al2O3 catalysts for partial oxidation of methane.

The effects of calcination temperature and feedstock pretreatment on the catalytic performance of Co/γ-Al(2)O(3) catalysts were studied for partial oxidation of methane (POM) to synthesis gas, with emphasis on the role of feedstock pretreatment. The physicochemical properties of the catalysts were characterized by N(2) adsorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), H(2) temperature-programmed reduction (H(2) -TPR), and Raman spectroscopy. The results showed that the pretreatment of the catalyst by reaction gas significantly improved the catalytic activity and stability for the POM reaction. On the other hand, the effect of calcination temperature was less significant. Although the initial activity was increased by an increased calcination temperature, the catalyst without the feedstock pretreatment suffered a rapid deactivation. The reaction-atmosphere pretreatment was revealed as a process that mainly modified the surface structure of the catalyst. In that process, the formation of a CoAl(2)O(4) -like compound led to high Co metal dispersion after reduction, and the transformation of the carrier into α-Al(2)O(3) occurred over the catalyst surface. Both the high dispersion of cobalt and the presence of α-Al(2)O(3) surface phase were assumed as the important factors resulting in an excellent catalytic performance in terms of high activity and high stability.

Enhancement of Astragalus polysaccharide on the immune responses in pigs inoculated with foot-and-mouth disease virus vaccine.

The effects of Astragalus polysaccharides (APS) on the immune response in pigs immunized with foot-and-mouth disease virus (FMDV) vaccine were investigated. Fifteen pigs were randomly divided into five groups. Four groups were vaccinated with a FMDV inactivated vaccine. Pigs in three experimental groups were administered varying doses of APS (APS1, 5mg/kg; APS2, 10mg/kg; APS3, 20mg/kg). The influence of APS on the number of CD3(+)CD4(-)CD8(+) cytotoxic T cells, CD3(+)CD4(+)CD8(+) T helper memory cells, and CD3(-)CD4(-)CD8(+) natural killer cells among peripheral blood lymphocytes (PBL) in the three APS groups were significant compared to the vaccine group. In vitro stimulation of PBL by Con A and LPS in APS groups induced a stronger proliferative response at 2 and 6 weeks post-inoculation (PI). APS markedly increased the titer of FMDV-specific antibody in a dose-dependent manner, and up-regulated mRNA expression of IFN-γ and IL-6. APS could potentially be used as an immunomodulator for a FMDV vaccine and provide better protection against FMDV.

Integrating miRNA and mRNA expression profiles in response to heat stress-induced injury in rat small intestine.

The molecular mechanisms underlying the pathophysiology of heat stress in the small intestine remain undefined. Furthermore, little information is available concerning changes in microRNA (miRNA) expression following heat stress. The present study sought to evaluate miRNA and mRNA expression profiles in the rat small intestine in response to heat stress. Male Sprague-Dawley rats were subjected to 2 h of heat stress daily for ten consecutive days. Rats were sacrificed at specific time points immediately following heat treatment, and morphological changes in the small intestine were determined. The miRNA and mRNA expression profiles from sample of small intestine were evaluated by microarray analysis. Heat stress caused pronounced morphological damage in the rat small intestine, most severe within the jejunum after 3 days of heat treatment. A mRNA microarray analysis found 270 genes to be up-regulated and 122 genes down-regulated (P ≤ 0.01, ≥2.0-fold change) in the jejunum after heat treatment. A miRNA microarray analysis found 18 miRNAs to be up-regulated and 11 down-regulated in the jejunum after heat treatment (P ≤ 0.05). Subsequent bioinformatic analyses of the differentially expressed mRNAs and miRNAs were carried out to integrate miRNA and mRNA expression and revealed that alterations in mRNA following heat stress were negatively correlated with miRNA expression. These findings significantly advance our understanding of the regulatory mechanisms underlying the pathophysiology of heat stress-induced injury in the small intestine, specifically with regard to miRNAs.