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In this study, traditional strongly endothermic anaerobic retorting (AR) and relatively novel self‐heating retorting (SHR) processes for oil shale (OS) were investigated and compared in detail. These studies mainly involve the structural and quantitative evolution of organic matters in OS during retorting, including varieties of crystallite parameters, carbon framework structure, amounts of various structural carbons and toxic polycyclic aromatic hydrocarbons, and so on. The obtained results well elucidate some reaction pathways in AR and SHR as well as certain differences between the two retorting processes. Moreover, based on our former work that verifies SHR greatly simplifies retorting operation by in situ generating heat to replace external heat carrier/provision, this study further demonstrates that SHR also alleviates the environmental effect of organic toxic residues as compared to AR. The present study provides some critical results not only for penetrating the reaction mechanism but also for assessing or controlling the environmental impact of both retorting processes. [ABSTRACT FROM AUTHOR]

Oil shale (OS) is a particularly promising alternative fossil fuel source. However, very different from coal, its inorganic mineral content is very high. The organic matters (mainly kerogen) are finely distributed in the inorganic minerals. Therefore, the minerals may affect the processing of OS, whose elucidation is critical to the choice of processing conditions. In this work, different minerals (SiO2, CaCO3, and Al2O3) were added to OS with different mass ratios of OS to mineral, respectively. Then, the thermogravimetric (TG) technique was employed to analyze the reaction behavior of these different OS/mineral mixtures in N2and in air for studying the influence of minerals on the OS pyrolysis in N2(i.e., retorting) and on the OS combustion in air. The results show that CaCO3and Al2O3have a promoting effect on both pyrolysis and combustion of OS, and they can decrease the reaction activation energy of both kinds of processes. However, SiO2has an inhibitive effect and can increase the reaction activation energy for both kinds of processes. It is hoped that the present study can further increase the understanding toward the effect of different minerals on the OS reactions. [ABSTRACT FROM PUBLISHER]

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]

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: Carbon nanotubes encapsulated Fe nanowire composites were synthesized via pyrolyzing of ferrocene. 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 characteristic effects by the encapsulation of metal Fe were investigated in a frequency range of 8–18 GHz. With matching thickness of 3.5 mm, the maximum reflection loss is about −22.73 dB for the absorber. The bandwidth corresponding to the reflection loss below −10 dB is more than 4.22 GHz. With increasing thickness, the peak value of the reflection loss shifts to a lower frequency. [Copyright &y& Elsevier]

Abstract: Fe-filled carbon nanotubes were prepared reliably and economically via pyrolyzing of ferrocene and activated carbon. The sample was characterized by high-resolution transmission electron microscopy, electron diffraction and fast Fourier transforms. The complex relative permittivity and permeability parameters were measured in a frequency range of 2–18GHz and microwave absorbing behavior was investigated. The sample exhibits the maximum reflection loss and the widest bandwidth of below −5dB is −11.29dB and 4.13GHz (matching thickness=2.5mm), respectively. [Copyright &y& Elsevier]