Macerals of lignite and the effect of alkali treatment on the structure and combustion performance of lignite

Suppressing the spontaneous combustion of lignite is of great significance for safe transportation and efficient utilization of lignite. Taking the Shengli lignite as the research object, two different macerals, inertinite and huminite, were selected by optical microscope, and treated with NaOH respectively to study the relationship between the structure and combustion reaction performance of different macerals and lignite treated with NaOH. The structure of the prepared coal samples was characterized by SEM-EDS, XPS, FT-IR, XRD and Raman, and the changes of the main functional groups were analyzed. The effect of NaOH treatment on the combustion performance of different maceral lignite was investigated by TGA. The results showed that the ignition temperature of huminite lignite was about 10 ℃ earlier than that of inertinite, but the comprehensive combustion characteristic index of inertinite lignite was slightly higher than that of huminite. After the NaOH treatment, the lignite of different macerals showed a hysteresis of combustion, there were two obvious weight losses in the range of 200−500 ℃ and 650−800 ℃, respectively, and the mass loss was mainly concentrated in the second weight loss, in particular, the effect of huminite lignite was more significant, and the temperature corresponding to the maximum combustion reaction rate was about 60 ℃ behind that of inertinite. The kinetic analysis of the combustion process of the coal samples showed that the activation energy of combustion reaction of lignite with different macerals significantly increased after the NaOH treatment, and the huminite lignite was higher than that of inertinite lignite. The XPS/FT-IR results revealed that the contents of carboxylic oxygen-containing functional groups in different macerals of lignite treated by NaOH decreased, the main reason is that in the process of NaOH treatment, Na+ interacted with the carboxylic oxygen-containing functional groups in lignite to form the sodium carboxylate structure, and the relative amount of the sodium carboxylate structure in huminite coal was relatively large. It is believed that the inhibitory effect on the combustion of lignite with different macerals is attributed to the stability of the sodium carboxylate structure, and the number of the sodium carboxylate structure formed by combining with Na is the main reason for the difference in its combustion performance. The XRD/Raman analysis indicates that the formation of the sodium carboxylate structure in lignite leads to the increase of the order degree of carbon microcrystalline structure, and the order degree of huminite lignite is higher than that in inertinite

Dynamic Mechanical Property of Kaolinite/Styrene-Butadiene Rubber Composites

International audienceThe dynamic properties of kaolinite/styrene-butadiene rubber (SBR) composites filled by kaolinite were investigated to evaluate their real-world engineering applications. The results of field emission scanning electron microscopy (SEM), and transmission electron microscopy (TEM) revealed that the rubber chains were confined within the interparticle space of kaolinites, and that the nanoscale kaolinites exhibited a fine and physical dispersion in the SBR matrix. The dynamic properties of kaolinite/SBR composites were investigated by performing dynamic mechanical analysis (DMA) and rubber processing analysis (RPA). Both the decrease in kaolinite particle size and the increase in kaolinite content can greatly improve the storage modulus and reinforcing effect of kaolinite/SBR composites. A small particle size and a low filled content of kaolinite filler is favourable for the dynamic properties of kaolinite/SBR composites for tire products. The filler networking phenomenon attributed to the agglomeration-de-agglomeration of filler particles intensified as the kaolinite particle size was reduced and the kaolinite content was increased, which resulted from the increase in the unit volume fraction of kaolinite in the rubber matrix and the stronger interaction of kaolinite particles in the composite matrix. Introduction. Layered clay minerals/polymer nanocomposites have received considerable attention from the industry and academic researchers because these materials have exhibited remarkably improved properties, such as improved mechanical properties and thermal ability, enhanced barrier property, and decreased flammability [1-7]. In particular, rubber is an important class of polymer materials because of its outstanding characteristics and special applications [8]. Many researchers have applied different approaches to modify clay minerals, which are then incorporated into rubber matrix by latex blending and simple melt mixing [5, 9]. Such practices have achieved slight improvements in the mechanical, thermal, and barrier properties of clay/rubber composites [6, 8, 10, 11]

Research Progress on Application in Energy Conversion of Silicon Carbide-Based Catalyst Carriers

In modern industrial production, heterogeneous catalysts play an important role. A catalyst carrier, as a constituent of heterogeneous catalysts, is employed for supporting and loading active components. The catalyst carrier has a considerable impact on the overall acting performance of the catalysts in actual production. Therefore, a catalyst carrier should have some necessary properties such as a high specific surface area, excellent mechanical strength and wear resistance, and better thermal stability. Among the candidate materials, silicon carbide (SiC) has excellent physical and chemical properties due to its special crystal structure; these properties include outstanding thermal conductivity and remarkable mechanical strength and chemical stability. Therefore, SiC materials with a high specific surface area basically meet the requirements of catalyst carriers. Accordingly, SiC has broad application prospects in the field of catalysis and is an ideal material for preparing catalyst carriers. In the present study, we reviewed the preparation methods and the variation in the raw materials used for preparing SiC-based catalyst carriers with high specific surface areas, in particular the research progress on the application of SiC-based catalyst carriers in the field of energy-conversion in recent years. The in-depth analysis indicated that the construction of SiC with a special structure, large-scale synthesis of SiC by utilizing waste materials, low-temperature synthesis of SiC, and exploring the interaction between SiC supports and active phases are the key strategies for future industrial development; these will have far-reaching significance in enhancing catalytic efficiency, reutilization of resources, ecological environmental protection, energy savings, and reductions in energy consumption

Research Progress on Application in Energy Conversion of Silicon Carbide-Based Catalyst Carriers

In modern industrial production, heterogeneous catalysts play an important role. A catalyst carrier, as a constituent of heterogeneous catalysts, is employed for supporting and loading active components. The catalyst carrier has a considerable impact on the overall acting performance of the catalysts in actual production. Therefore, a catalyst carrier should have some necessary properties such as a high specific surface area, excellent mechanical strength and wear resistance, and better thermal stability. Among the candidate materials, silicon carbide (SiC) has excellent physical and chemical properties due to its special crystal structure; these properties include outstanding thermal conductivity and remarkable mechanical strength and chemical stability. Therefore, SiC materials with a high specific surface area basically meet the requirements of catalyst carriers. Accordingly, SiC has broad application prospects in the field of catalysis and is an ideal material for preparing catalyst carriers. In the present study, we reviewed the preparation methods and the variation in the raw materials used for preparing SiC-based catalyst carriers with high specific surface areas, in particular the research progress on the application of SiC-based catalyst carriers in the field of energy-conversion in recent years. The in-depth analysis indicated that the construction of SiC with a special structure, large-scale synthesis of SiC by utilizing waste materials, low-temperature synthesis of SiC, and exploring the interaction between SiC supports and active phases are the key strategies for future industrial development; these will have far-reaching significance in enhancing catalytic efficiency, reutilization of resources, ecological environmental protection, energy savings, and reductions in energy consumption

Synthesis, crystal structure, and photophysical properties of a double open cubane-like Cd(II) complex based on 2-substituted-8-hydroxyquinoline

<div><p>A 2-substituted-8-hydroxyquinoline (<i>E</i>)<b>-</b>2<b>-</b>[2<b>-</b>(3<b>-</b>thienyl)ethenyl]<b>-</b>8<b>-</b>quinolinol (HL) was synthesized and characterized by ESI-MS, NMR spectroscopy, and elemental analysis. Using solvothermal method, a tetranuclear complex [Cd₄L₆Br₂]·6DMF (<b>1</b>) was fabricated by assembly of Cd(II) with HL. X-ray structural analysis shows that <b>1</b> exhibits a double open cubane-like core structure, which is bridged by six 8-hydroxyquinolinate-based ligands. The supramolecular structure of <b>1</b> features a 3-D porous solid constructed by aromatic stacking interactions, C–H···<i>π</i> interactions and C–H···O hydrogen bonds. The assembly of cadmium salts and HL in solution was investigated by UV–vis and photoluminescence. We also studied the thermal stability and photophysical properties (fluorescent emission, lifetime, and quantum yield) of <b>1</b>. The results show that <b>1</b> emits yellow luminescence in the solid state.</p></div

Dual integrin αvβ 3 and NRP-1-Targeting Paramagnetic Liposome for Tumor Early Detection in Magnetic Resonance Imaging

Abstract Enhanced MRI (magnetic resonance imaging) plays a vital role in the early detection of tumor but with low specificity. Molecular imaging of angiogenesis could efficiently deliver contrast agents to the tumor site by specific targeted carriers. We designed and synthesized dual-targeted paramagnetic liposomes functionalized with two angiogenesis-targeting ligands, the αVβ3 integrin-specific RGD (Arg-Gly-Asp) and the neuropilin-1 (NRP-1) receptor-specific ATWLPPR (Ala-Thr-Trp-Leu-Pro-Pro-Arg) (A7R). These liposomes were proved to be in the nanoparticle range and demonstrated to effectively encapsulate paramagnetic MRI contrast agents Gd-DTPA (gadolinium-diethylenetriamine pentaacetic acid). T1 relaxivity of various liposome formulations was lower than pure Gd-DTPA but with no statistically significant difference. In vitro cellular uptake and competitive inhibition assay showed the higher binding affinity of dual-targeted liposomes to HUVECs (human umbilical vein endothelial cells) and A549 cells compared with pure Gd-DTPA, non-targeted, and single-targeted liposomes, which was proved to be mediated by the binding of RGD/ανβ3-integrin and A7R/NRP1. For MR imaging of mice bearing A549 cells in vivo, dual-targeted liposomes reached the highest SER (signal enhancement rate) value with a significant difference at all experimental time points. It was about threefold increase compared to pure Gd-DTPA and non-targeted liposomes and was 1.5-fold of single-targeted liposomes at 2 h post injection. The SER was lowered gradually and decreased only by 40% of the peak value in 6 h. Dual-targeted liposomes were likely to exert a synergistic effect and the specificity of delivering Gd-DTPA to the tumor site. Therefore, dual-ανβ3-integrin-NRP1-targeting paramagnetic liposome with a RGD-ATWLPPR heterodimeric peptide might be a potent system for molecular imaging of tumor