Boosting activity of γ-alumina-supported vanadium catalyst for isobutane non-oxidative dehydrogenation via pure V3.

The vanadium-based dehydrogenation (DH) catalyst is becoming a promise alternative to the industrial used Pt- and Cr-based catalysts, due to lower cost and less environmental threat. However, the low DH activity hampered the industrial application of vanadium-based catalysts. Herein, for the first time, we introduce a method to prepare high-efficiency vanadium-based catalyst by constructing pure V3+ species on γ-Al2O3 through treatment of as-prepared thiovanadate. The V3+ species contributes to not only enhancing the DH activity, but also fabricating the V3+-O/S acid-base pair with ideal strength and stability. The isobutene yield can reach as high as 56.9 wt%. Only Lewis acid is recognized on V3+/Al2O3 catalyst, while no Brønsted acid remains. The side-reactions are consequently inhibited, and the selectivity to isobutene is improved. Besides, with the increase of vanadium loadings, the Lewis acid content increases at first and then decreases, and the content of acid sites in middle strength keeps decreasing. Though the deposited coke on V3+/Al2O3 was just 2.5 wt% during 8.5 h consecutive DH reaction, the valence state of vanadium was still influenced and the fraction of inert V4+ species increased steadily. This study will improve the potential for industrial application of vanadium-based DH catalyst, and offer theoretical guidance for optimization of ideal DH catalysts.

Co-Catalysis for Hydroamidocarbonylation of Alkynes with Amides over a Bifunctional Ligand-Based Pd Catalyst.

The hydroamidocarbonylation of alkynes with amides allows for the synthesis of α,ß-unsaturated imides with the advantage of 100% atomic economy. Herein, the bifunctional ligand (L1) containing a sulfonic acid group (-SO3 H) and phosphino-fragment enable the Pd catalyst to accomplish the hydroamidocarbonylation of alkynes with amides. It was found that, due to an intramolecular synergetic effect, the L1-based Pd-catalyst exhibited much higher activity than the individual mechanical mixtures of Xantphos-based Pd-complex and MeSO3 H. The formation and stability of Pd-H species were promoted by the presence of L1, which was verified by in situ high-pressure FT-IR analysis. Under the optimized conditions, the target products of the branched imides were obtained with yields in the range of 46-87% over the L1-based Pd-catalyst. Advantageously, as an ionic ligand, the L1-based Pd-catalyst could be recycled for 4 runs in the ionic liquid of [Bmim]NTf2 without any obvious activity loss and detectable metal leaching.

Isobutane dehydrogenation over high-performanced sulfide V-K/γ-Al2O3 catalyst: Modulation of vanadium species and intrinsic effect of potassium.

Compared with industrial used Pt- and Cr-based catalyst in dehydrogenation (DH) of light alkanes, the sulfide V-K/γ-Al2O3 catalyst reported in this study shows lower cost and toxicity, and significant DH performance. The yield to isobutene reached as high as 52.9%, which is among the highest reported to date. We attribute such high isobutene yield to the precise modulation of polymerization degree for vanadium species via doping of potassium and indicating that the synergy between vanadium species and acid sites is critical to enhance the DH performance. Our previous work showed sulfidation promoted the increase of DH performance for vanadium-based catalyst, and we go further in this study to explore the correlation between increased range of DH performance and the added potassium. The different loaded potassium leads to variation in sulfidation degree, affecting the properties of vanadium species and acid properties consequently. The potassium was distributed uniformly on surface of the sulfide vanadium-based catalyst and was predominantly bonded with the vanadium species rather than with the γ-Al2O3 support. With increasing the potassium amount from 0 to 3 wt%, the acid amount kept decreasing, and some specific strong acid sites appeared once adequate sulfur was introduced in the V-K/γ-Al2O3 catalyst. The characterization and DFT results both revealed that the doped potassium contributes to regulating the vanadium species in the oligomeric state. The synergy between vanadium species and acid properties was regulated by the added potassium simultaneously, and thus the DH performance was enhanced. This study provides promising strategy for preparation of environment-friendly model industrial DH catalyst.

Study on Colloidal Model of Petroleum Residues through the Attraction Potential between Colloids.

The samples of DaGang atmospheric residue (DG-AR), Middle East atmospheric residue (ME-AR), TaHe atmospheric residue (TH-AR), and their thermal reaction samples were chosen for study. All the samples were fractioned into six components separately, including saturates plus light aromatics, heavy aromatics, light resins, middle resins, heavy resins, and asphaltenes. The dielectric permittivity of the solutions of these components was measured, and the dielectric permittivity values of the components can be determined by extrapolation, which increased steadily from saturates plus light aromatics to asphaltenes. Moreover, the Hamaker constants of the components were calculated from their dielectric permittivity values. The Van der Waals attractive potential energy between colloids corresponding to various models could be calculated from the fractional composition and the Hamaker constants of every component. It was assumed that the cores of colloidal particles were formed by asphaltenes and heavy resins mainly; the other fractions acted as dispersion medium. For the three serials of thermal reaction samples, the Van der Waals attraction potential energy between colloids for this kind of model was calculated. For TH-AR thermal reaction samples, the Van der Waals attraction potential energy presented the maximum as thermal reaction is going on, which was near to the end of coke induction period.

Probability of premature mortality caused by chronic respiratory disease and its changing trend during 2005-2015 in Guangdong province / 解放军医学杂志

Objective: To analyze the probability of premature mortality, mortality and standardized mortality of chronic respiratory diseases during 2005-2015 in Guangdong province, thus providing scientific and effective reference for further development of prevention and control of chronic respiratory diseases. Methods: The data of chronic respiratory disease were collected from the death registration system of 2005-2015 Guangdong province residents. The probability of premature mortality, mortality, age-standardized mortality and annual percent change (APC) were calculated. Chi-square test was used to compare the rates, the trend change was identified by linear regression. Results: During year 2005-2015, the probability of premature mortality decreased from 2.48% to 1.13%, and its APC was -7.87% (F=239.58, P<0.05). The percentage of deaths from chronic respiratory diseases decreased from 14.02% to 10.84% in total deaths, with the corresponding APC of -2.96% (F=21.12, P<0.05). The mortality decreased from 71.39/100,000 to 50.76/100,000, with the corresponding APC of -3.63% (F=41.49, P<0.05). The age-standardized mortality decreased from 107.31/100,000 to 61.83/100,000, with the corresponding APC of -5.64% (F=106.83, P<0.05). Conclusions Chronic respiratory diseases remain a major health hazard for residents in Guangdong province, although their incidence shows a downtrend, so further preventive and control measures are needed to reduce the premature death from chronic respiratory diseases.

[Effects of microbial inoculation on composting in a bioreactor].

A composting experiment with chicken manure was carried out in a lab-scaled bioreactor to study the effects of microbial inoculation (a single Bacillus megaterium and a compound VT agent) on the changes of the temperature, oxygen concentration, C/N ratio, WSC (water-soluble carbon), germination index (GI), and cellulase and dehydrogenase activity. The results showed that the use of compound VT agent was more effective in the growing of starting temperature and maintaining of the high-temperature during composting than the single Bacillus megaterium treatment. The oxygen concentration in the composting with inoculation (both Bacillus megaterium and VT) was lower than that of the composting without inoculation. Meanwhile, the inoculation with compound microbial inocula (VT) showed lower of C/N ratio, higher WSC concentration and higher GI in the compost than that of the individual microbial inoculation. Furtherly, microbial inoculation could increase the cellulase activity and dehydrogenase activity in the composting process and promote the decomposition of cellulose during the composting.