Ke Qiao

Clover leaf-shaped Al2O3 extrudate as a support for high-capacity and cost-effective CO2 sorbent

Amine-functionalized clover leaf-shaped Al(2)O(3) extrudates (CA) were prepared for use as CO(2) sorbent. The as-synthesized materials were characterized by N(2) adsorption, XRD, SEM and elemental analysis followed by testing for CO(2) capture using simulated flue gas containing 15.1% CO(2). The results showed that a significant enhancement in CO(2) uptake was achieved with the introduction of amines into CA materials. A remarkably high volume-based capacity of 70.1mg/mL of sorbent of this hybrid material suggests that it can be potentially used for CO(2) capture from flue gases and other stationary sources, especially those with low CO(2) concentration. The novel adsorbent reported here performed well during prolonged cyclic operations of adsorption-desorption of CO(2).

A review of the direct oxidation of methane to methanol

This article briefly reviewed the advances in the process of the direct oxidation of methane to methanol (DMTM) with both heterogeneous and homogeneous oxidation. Attention was paid to the conversion of methane by the heterogeneous oxidation process with various transition metal oxides. The most widely studied catalysts are based on molybdenum and iron. For the homogeneous gas phase oxidation, several process control parameters were discussed. Reactor design has the most crucial role in determining its commercialization. Compared to the above two systems, aqueous homogenous oxidation is an efficient route to get a higher yield of methanol. However, the corrosive medium in this method and its serious environmental pollution hinder its widespread use. The key challenge to the industrial application is to find a green medium and highly efficient catalysts.

Perspective on FCC catalyst in China

This paper provides an overview of the enormous challenge in processing heavier fluid catalytic cracking (FCC) feedstock and producing higher qualified liquid fuels. Besides optimizing the operation conditions of the FCC unit, it is crucial to design new catalysts especially for heavier and inferior feedstock. In this paper, a new concept, stepwise structure of catalyst, was postulated and a potential new catalyst based on stepwise structure design was prepared.

The effects of magnesium of Zn–Mg–Al additives on catalytic cracking of VGO and in situ reduction of sulfur in gasoline

The scope of the present study is to describe the cracking behavior of hydrocarbons and the reduction of sulfur in gasoline in fluid catalytic cracking (FCC) process using Zn–Mg–Al additives with varying the Mg/Al molar ratios. Experiments have been carried out on a micro-activity-test (MAT) reactor using high-sulfur vacuum gas oil (VGO) feed and zinc impregnated Mg–Al spinels as additive and the commercial cracking catalyst. It was found that Zn–Mg–Al additives exhibited enhanced Lewis acidity compared with the corresponding Zn-free Mg–Al spinels. The MAT results indicated that the addition of additives reduced the yields of liquid petroleum gas and coke at low Mg contents but increased the coke yield at high Mg contents. Overall, the additives improved the yields of gasoline and diesel. It has also been shown that the rich Lewis acidity had a positive effect on the conversion of aromatic sulfur species of gasoline and the maximum reduction of gasoline sulfur was achieved with Zn/Mg4.0Al2O3 due to the synergistic effect of basicity and Lewis acidity.

Preparation and characterization of hierarchical USY by post-treatment

Two modifying agents, citric acid and EDTA-2Na, were used to modify USY zeolite to obtain the hierarchical USY with high crystallinity. XRD, N2 isothermal sorption, 27Al and 29Si NMR, and TEM were adopted to characterize the dealumination process in the post-treatment of USY. The results showed that all modified USY have increased surface areas and pore volume due to the removal of non-framework Al species. Besides, framework dealumination occurred in the modification process. USY-EC, which was modified by the combined effects of citric acid and EDTA-2Na, has the highest SiO2/Al2O3 ratio of 19.40 and relatively high crystallinity.

Nitrogen and Sulfur Co-Doped Graphene Nanosheets to Improve Anode Materials for Sodium-Ion Batteries

Sodium-ion batteries (SIBs) attract more attention because of sodiums abundant availability, affordable price, and potential to be an effective anode material. Meanwhile, carbon-based materials provide the most promising anode materials. Because of the large radius of sodium ions, SIBs do not exhibit favorable electrochemical performance. Introducing heteroatoms into the carbon-lattice is an effective strategy to enlarge the interlayer space of carbon-based materials which can improve carbons electrochemical performance. In addition, anode materials with a surface-induced capacitive process can enhance the SIBs electrochemical performance because its capacitive process increases the kinetics of ion diffusion. Here, we describe an SIBs anode material containing nitrogen and sulfur co-doped graphene sheets [denoted as poly(2,5-dimercapto-1,3,4-thiadiazole) (PDMcT)/reduced graphene oxide (RGO)] which are synthesized via carbonization of PDMcT polymerized on the surface of GO. PDMcT/RGO exhibited high capacities (240 mA h g-1 at 500 mA g-1), improved rate performance (144 mA h g-1 at 10 A g-1), and good cycling stability (153 mA h g-1 after 5000 cycles at 5000 mA g-1). These unique results are attributed to the enlarged interlayer spacing and electronic conductivity from the heteroatoms which facilitate the sodium ions insertion and electron transport. These results represent that PDMcT/RGO is a great potential anode material for SIBs.

Preparation and hydrodesulfurization properties of cobalt–molybdenum–phosphorous catalysts for removal of dibenzothiophene

Abstract In this study, a series of cobalt–molybdenum–phosphorous acid (Co–Mo–P) impregnating solutions with various Co/Mo molar ratios (0.2, 0.25, 0.3, 0.35) were synthesized, and desulfurization catalysts were prepared by mixing the solutions with γ-Al2O3 through an incipient-wetness impregnation method. The Co–Mo–P supported γ-Al2O3 catalysts were tested in the hydrodesulfurization of dibenzothiophene (DBT). The catalysts were characterized by N2 adsorption–desorption isotherms, XRD, py-FT-IR, and HRTEM. Nitrogen adsorption measurements revealed that the as-prepared catalysts possess high specific surface area and appropriate pore size. XRD showed that Co species and Mo species were well dispersed on the surface of γ-Al2O3 with the addition of phosphoric acid. Py-FT-IR showed that the catalyst with a Co/Mo molar ratio of 0.25 exhibited more Lewis and Brønsted acid sites. The stacking number and slab length of MoS2 nanoclusters changed with various Co/Mo molar ratios as revealed by HRTEM. Among the tested catalysts, Co–Mo–P supported γ-Al2O3 with Co/Mo molar ratio of 0.25 exhibited higher activity and selectivity of biphenyl than the other catalysts.