Search

Oil shale (OS), from which petroleum-like shale oil can be obtained via retorting, is one of the most promising alternative fossil fuels due to its huge reserve. A main obstacle to OS retorting is the required high-energy input, particularly for underground retorting. Recently a low-energy-input route via self-heating retorting (SHR) was developed (Guo et al., 2013 and 2014). However, its unclear reaction mechanism hinders its further development. Herein, the reaction mechanism of SHR was analyzed by using Huadian OS and thermal analysis techniques. The results suggest anaerobic retorting (AR) used for preparing shale oil produces substantial residual carbon (RC) byproduct, and the heat contained in RC is more than the energy input needed by an AR process. While in SHR process, by reaction-kinetics control, part of kerogen is first pyrolized into oil and RC before exposed to air, and then RC in-situ reacts with the diffused air to release heat for progressing SHR and replacing external heat supply. In-situ utilizing RC by SHR process partly explains why SHR itself provides heat to increase retorting temperature but without obviously lost shale-oil yield. [ABSTRACT FROM AUTHOR]

Recently a facile low-energy-input retorting route but without marked loss in the shale-oil yield is developed, which is achieved by a self-heating effect, that is, spontaneously increasing retorting temperature in the absence of external heat provision (Guo et al., 2013, 2014). In this work, the applicability of self-heating retorting (SHR) process to three Chinese oil shales from different places (i.e., Longkou, Huadian and Fushun) is studied. Of these three oil shales, Fushun oil shale is associated with coal and was previously abandoned during coal mining due to its not high kerogen or oil content. The results show that it’s hard for Fushun oil shale to obtain satisfying self-heating effect, while Longkou or Huadian oil shale with higher kerogen or oil content shows satisfactory SHR. However, by adding suitable amounts of Longkou or Huadian oil shale into Fushun oil shale, a satisfying self-heating effect can be obtained as well. Thus, the relatively low-grade Fushun oil shale can also be well utilized to produce shale oil via this facile SHR route. Moreover, to utilize Fushun oil shale with a greener SHR process, the process can be performed by co-retorting Fushun oil shale with pine needles, a kind of renewable biomass. This finding also provides a new starting point for exploring plentiful biomass resources to utilize low-grade oil shale to produce oil in the future work. [ABSTRACT FROM AUTHOR]

Caustic calcined magnesia (main component is MgO) can be used to produce Mg(OH) 2 by ammonium-circulation method (reaction steps: (1) MgO + 2NH 4 + → Δ Mg 2 + + 2NH 3 ↑ + H 2 O and (2) Mg 2 + + 2NH 3 ↑ + 2H 2 O → Mg(OH) 2 ↓ + 2NH 4 + ; Overall: MgO + H 2 O → Mg(OH) 2 ↓). NH 4 Cl, NH 4 NO 3 and (NH 4 ) 2 SO 4 have exhibited the ability to be used as a circulation medium. In this work, ammonium acetate (NH 4 Ac) was investigated as a circulation medium. The purity of the used caustic calcined magnesia (i.e., MgO content) is 85 wt.%. The results show that NH 4 Ac is a much more efficient circulation medium than NH 4 Cl, NH 4 NO 3 or (NH 4 ) 2 SO 4 is. Step (1) in the ammonium-circulation method can be significantly accelerated if NH 4 Ac is used as the circulation medium. The reason for the high efficiency of NH 4 Ac was also analyzed. By using NH 4 Ac as the circulation medium, rose petal-like Mg(OH) 2 precipitate can be prepared in the presence of polyethylene glycol. The purity of the prepared Mg(OH) 2 is more than 99 wt.%. [ABSTRACT FROM AUTHOR]

Abstract: The effect of the minerals of Huadian oil shale on a low-energy input retorting route was studied. This special retorting route was achieved by a self-heating effect, that is, spontaneously increasing retorting temperature in the absence of external heat provision (Guo et al., 2013) [12]. Oil shale was first demineralized with HCl, HNO3 or HF before used in the self-heating retorting. The oil shales treated with different acids, and their corresponding semicokes attained after retorting were also characterized. The results showed that using HF-treated oil shale produces the best self-heating effect and the highest oil yield. Using HNO3-treated oil shale also promotes the self-heating effect. While using HCl-treated oil shale remarkably worsens the self-heating effect, but it gives a higher oil yield than using HNO3-treated or raw oil shale. The reasons are also analyzed. Although different acid treatments affect the self-heating effect differently, all the attained oils mainly consist of various hydrocarbons, however, the product distributions are different. [Copyright &y& Elsevier]

Abstract: Through-porous steel fiber matrix with high specific surface area and self-support strength was examined as the support of TiO2 film photocatalyst. TiO2 was uniformly and conformally deposited onto the surface of the metal skeleton of the porous steel fiber matrix via atomic layer deposition method so that the porosity as well as gas permeability of the matrix is maintained. For further improving the photocatalytic activity, noble metals (Au and Pt/Pd alloy) were sputtered onto the surface of TiO2 photocatalyst. The photodegradation of methyl orange was used for evaluating the photocatalytic properties. The results show that compared with TiO2 films deposited on flat Si wafers, TiO2 films on the porous support display higher photocatalytic activities, owing to their higher specific surface areas. The photocatalytic activity of TiO2 on porous support was not enhanced by Au, while it was remarkably improved by Pt/Pd. The TiO2 photocatalysts were also analyzed by scanning electron microscopy and X-ray photoelectron spectroscopy. [Copyright &y& Elsevier]

Abstract: Polyaniline(PANi)/Fe3O4 nanocomposites have been prepared via in situ chemical oxidative polymerization directed with cationic surfactant cetyltrimethylammonium bromide (CTAB). The studies show that PANi can coat Fe3O4 nanoparticles. CTAB can produce insoluble substance with initiator of polyreaction, and plays a very important role for the coating of Fe3O4 nanoparticles by PANi. Many Fe3O4 nanoparticles are bald without being coated by PANi when CTAB is replaced by anionic surfactant, so anionic surfactant can not play the role of CTAB. [Copyright &y& Elsevier]

Abstract: Co-filled carbon nanotubes composites were synthesized via using a simple and efficient wet chemistry solution method. The samples were characterized by transmission electron microscopy. Microwave-absorbing properties were investigated by measuring complex permittivity and complex permeability of the absorber in a frequency range of 2–18GHz. The reflection loss (R.L.), matching frequency (f m) and matching thickness (d m) were calculated using the theory of the absorbing wall. The electromagnetic properties and microwave-absorbing characteristics effects of the modified carbon nanotubes by the encapsulation of metal Co were investigated. A matching thickness is found corresponding to a matching frequency. The maximum reflection loss is about −39.32dB and the bandwidth corresponding to the reflection loss below −10dB is 3.47GHz. With increasing thickness, the maximum reflection loss shifts to lower frequency. [Copyright &y& Elsevier]

Polymorphism- or morphology-controllable synthesis of CaCO 3 is of significance. Usually only calcite CaCO 3 can be obtained from the ordinary CO 2 -Ca(OH) 2 solution route; the very low solubility of Ca(OH) 2 also causes many defects with this route. The route by CaCl 2 and Na 2 CO 3 exhibits some advantages, but the consumption of Na 2 CO 3 is a deficiency. Therefore, this work studies the precipitation of CaCO 3 with CaCl 2 in NH 3 -CO 2 aqueous solution, which will make the overall reaction “CaCO 3   →   CaCO 3 ” if tracing the origin of the reactants. A main focus of the present work is to elucidate how to obtain various CaCO 3 polymorphs with different morphologies through this synthesis system and the corresponding crystal growth mechanism. The results show that, just by simply regulating the reaction conditions, all three anhydrous CaCO 3 polymorphs with various morphologies (e.g., cubic, lamellar, spherical, needle-like and branched) can be obtained in the absence of any additives. The crystal growth process can be well explained based on either Ostwald ripening or dissolution-recrystallization mechanism, depending on the reaction conditions. In addition, the rare phase transition of metastable vaterite to metastable aragonite can also be obtained from the present synthesis system, besides the usual phase transition of vaterite to the most thermodynamically stable calcite. This work provides the essential theoretical support for further developing a green process for CaCO 3 production by using various calcium-containing carbonate minerals, such as limestone, calcite and dolomite. [ABSTRACT FROM AUTHOR]

Use oxide-supported catalyst in green solvent, hot water : Au is anchored on oxide via Au┄O-M interaction (M = Fe, Ti, etc). Basic aqueous catalytic system may destruct a part of O M bonds into oxygen vacancies and weaken Au/support interaction, causing leaching and aggregation of Au. Three simple methods synergistically improve reusability of catalyst. [Display omitted] • Three facile ways synergistically improve catalyst reusability in green solvent, water. • They raise support stability and Au/support interaction to reduce leaching and aggregation of Au. • Nano supports interact with Au more strongly, and are more stable in hot basic water. • Nano TiO 2 is more stable due to the stronger surface Ti O bond, in line with BOLS theory. Obtaining reusable catalysts and using water as a green solvent still remain huge challenges. Various oxides are frequently used as the support, however, the aqueous catalytic systems, particularly in hot basic water, may decrease their stability and thus cause leaching or aggregation of the supported metal nanoparticles (NPs). In this work, three very simple methods in catalyst preparation are demonstrated to greatly improve the reusability of oxide-supported catalysts in 100 °C basic water, by systematically studying a series of oxides as well as carbons as support of gold (Au) NPs and employing Suzuki-Miyaura cross-coupling (SMCC) reaction as a probe. These methods are prerequisites for obtaining both excellent activity and recyclability. Absence of any of them will badly improve leaching or aggregation of Au NPs. The reasons for the synergistically improved reusability are also elucidated in details. Though it's extremely hard to thoroughly overcome leaching in hot water, this work achieves the application of Au/oxide to SMCC reaction in water with higher utilization efficiency of Au than some reported work in organic solvent or with other supports. The present work can serve as supplementary strategies to assist in designing high-performance oxide-supported catalysts for varieties of similar aqueous systems. [ABSTRACT FROM AUTHOR]