A novel process was developed for the preparation of ultrafine silica from potash feldspar. In the first step, potash feldspar was roasted with Na2CO3 and was followed by leaching using NaOH solution to increase the levels of potassium, sodium, and aluminum in the solid residue. The leaching solution was then carbonated to yield ultrafine silica. The optimized reaction conditions in the roasting process were as follows: an Na2CO3-to-potash feldspar molar ratio of 1.1, a reaction temperature of 875°C, and a reaction time of 1.5 h. Under these conditions, the extraction rate of SiO2 was 98.13%. The optimized carbonation conditions included a final solution pH value of 9.0, a temperature of 40°C, a CO2 flow rate of 6 mL/min, a stirring intensity of 600 r/min, and an ethanol-to-water volume ratio of 1:9. The precipitation rate and granularity of the SiO2 particles were 99.63% and 200 nm, respectively. We confirmed the quality of the obtained ultrafine silica by comparing the recorded indexes with those specified in Chinese National Standard GB 25576―2010.

SrCO3 was formed and added as a carrier into copper-based catalyst (CuZnAl catalyst) prepared by hydrothermal method before the catalyst incorporates with HZSM-5. The CuZnAlSr catalyst was characterized by SEM, BET, XRD, IR, and activity-evaluation system in a fixed-bed tubular reactor equipped with chromatograph (GC). The conversion of CO2 reaches 30.30 %, and the overall yield of methanol and dimethyl ether is 27.80 %. Catalytic property as to CO2 conversion has only slight decrease even up to 150 h of reaction time. The addition of SrCO3 enhanced the activity of the catalyst through providing a tridimensional frame and electron transfer bridge.

A graphene encapsulated LiFePO4 composite has been synthesized by self-assembly of surface modified LiFePO4 and graphene oxide with peptide bonds, followed by reduction. The graphene forms a continuous conductive coating network connecting the LiFePO4 nanoparticles to facilitate electron transportation, resulting in excellent high rate capability with 70% capacity retention at 50 C rate. The apparent activation energy of the graphene encapsulated LiFePO4 composite (9.6 kJ mol−1) is much lower than that of the carbon coated LiFePO4 (14.6 kJ mol−1). An excellent cycling performance is also demonstrated, in which the capacity loss is less than 8.6% after 950 cycles at 10 C. Therefore, this hybrid material is promising for use as a cathode material for high rate lithium ion batteries.

By employing zinc acetate and sodium hydroxide as raw materials, ultrafine ZnO powders with different morphologies were successfully synthesized through hydrothermal method. The influences of the reaction temperature, the OH−/Zn2+ mol ratio and the reaction time on the morphologies of the ZnO powders were discussed. The reaction conditions were obtained, under which the ZnO of flower-like particles, micro-rods and flake particles was synthesized, respectively. The crystal structures and morphologies of those ZnO particles were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The ZnO with flower-like structures was composed of lots of micro-rods with hexagon morphology. The XRD patterns indicated that the ZnO powders were hexagonal wurtzite structures with high purity. Finally, the growth mechanism of the ZnO particles was discussed.

Stimulated by recent preparation and characterization of the first C50Cl10 fullerene derivative with five fused pentagons and four novel chlorinated fullerene derivatives, C54Cl8, C56Cl12, C66Cl6 and C66Cl10 with the triple sequentially fused pentagons, 30 exohedral chlorine derivatives of small fullerenes C30–C48 have been reported here. The geometrical structures and electronic properties of them are studied using density functional theory (DFT) at the B3LYP/6-31G∗ level. The HOMO–LUMO gaps, reaction energies, and aromaticities commonly used for chemical viability of chlorinated small fullerenes were compared with these values of the two most stable fullerene derivatives C50Cl10 and C60Cl30. The presented data reveal that many unknown fullerene derivatives are stable molecules, especially for C32Cl20 (3, D3d), C36Cl18 (13, D3h), and C40Cl16 (40, Td). The stable behavior of them resembles the well-known C50Cl10. It is quite possible that they can be synthesized experimentally in the solid after C50.

Due to the high absolute humidity of real flue gas, activated carbon, a hydrophobic adsorbent, was used to selectively adsorb CO2 by vacuum swing adsorption in this study. The objective of this work is to study the feasibility and advantage of CO2 capture along with simultaneous moisture removal by activated carbon and the effect of H2O on CO2 capture from wet flue gas streams. Through experiment and analysis, the “S” shape isotherms of water indicated water was easier to be desorbed from activated carbon. Then a cone shape model was proposed to depict water distribution inside the adsorption bed. As a consequence, water vapor hardly influenced the CO2 capture performance. Moreover, the process can be operated under a relatively high vacuum pressure and short evacuation time. The preliminary results showed that our one-bed VSA process could yield a good CO2 recovery of over 80% and a reasonable purity of 43%.

Different VSA (Vacuum Swing Adsorption) cycles and process schemes have been evaluated to find suitable process configurations for effectively separating CO2 from flue gases from different industrial sectors. The cycles were studied using an adsorption simulator developed in our research group, which has been successfully used to predict experimental results over several years. Commercial zeolite APGIII and granular activated carbon were used as the adsorbents. Three-bed VSA cycles with- and without-product purge and 2-stage VSA systems have been investigated. It was found that for a feed gas containing 15% CO2 (representing flue gas from power plants), high CO2 purities and recoveries could be obtained using a three-bed zeolite APGIII VSA unit for one stage capture, but with more stringent conditions such as deeper vacuum pressures of 1–3 kPa. 2-stage VSA process operated in series allowed us to use simple process steps and operate at more realistic vacuum pressures. With a vacuum pressure of 10 kPa, final CO2 purity of 95.3% with a recovery of 98.2% were obtained at specific power consumption of 0.55 MJ·(kg CO2)− 1 from feed gas containing 15% CO2. These numbers compare very well with those obtained from a single stage process operating at 1 kPa vacuum pressure. The feed CO2 concentration was very influential in determining the desorption pressure necessary to achieve high separation efficiency. For feed gases containing > 30% CO2, a single-stage VSA capture process operating at moderate vacuum pressure and without a product purge, can achieve very high product purities and recoveries.Flue gas CO2 concentration differs from different industrial sectors, and hence different VSA cycle configurations are required. A new 13X zeolite-APGIII was compared with coconut carbon to find the better candidate for the VSA. Different VSA cycles and process schemes have been evaluated in order to find suitable process configurations to effectively separate CO2 from flue gas from different industrial sectors, and we also analyze the important processing parameters and the energy consumption for VSA cycle. The goal of this study was to design suitable VSA process configurations to upgrade CO2 concentration in various feed streams to > 95%, at a minimum capture rate of 80%.Download full-size image

A graphene encapsulated LiFePO4 composite has been synthesized by self-assembly of surface modified LiFePO4 and graphene oxide with peptide bonds, followed by reduction. The graphene forms a continuous conductive coating network connecting the LiFePO4 nanoparticles to facilitate electron transportation, resulting in excellent high rate capability with 70% capacity retention at 50 C rate. The apparent activation energy of the graphene encapsulated LiFePO4 composite (9.6 kJ mol−1) is much lower than that of the carbon coated LiFePO4 (14.6 kJ mol−1). An excellent cycling performance is also demonstrated, in which the capacity loss is less than 8.6% after 950 cycles at 10 C. Therefore, this hybrid material is promising for use as a cathode material for high rate lithium ion batteries.