Resources Chemicals and Materials最新文献

The inclined micro-fluidized bed (MFB) can enhance heat and mass transfer rates compared to the vertically aligned counterparts, but the increased significance of surface forces and wall effects may cause poor fluidization performance. In this paper, the effects of column inclination and different particle-to-bed ratios (d_P/d_B) on the solid hydrodynamics are investigated in an inclined micro-fluidized bed. The results validated the suitability of using the Ergun equation to predict minimum fluidization velocities due to small deviations between 1.01 and 1.81 times the theoretical values, for a particle-to-bed ratio ranging from 0.025 to 0.165 at inclinations between 0° and 10°. Investigation into the effects on bed expansion behavior showed that the bed contracted with an increase in bed inclination. An unexpected observation during the bed expansion was the appearance of a secondary high voidage region and the appearance of strong circulation patterns with an increase in bed inclination. A detailed analysis of this phenomenon suggested the presence of a critical angle at 6° and 10° for the 85 µm particles, 4 × 4 mm bed cross-section and 165 µm particles, 1 × 1 mm bed cross-section, respectively. However, the liquid-solid back-mixing was observed due to the modified particle trajectories resulted in the disappearance of the high voidage region. This paper gives new insights into the micro-fluidization behavior in inclined beds thus contributing to the development of micro-fluidized beds and their future applications.

Most natural resources are processed as particle-fluid multiphase systems in chemical, mineral and material industries, therefore, discrete particles methods (DPM) are reasonable choices of simulation method for engineering the relevant processes and equipments. However, direct application of these methods is challenged by the complex multiscale behavior of such systems, which leads to enormous computational cost or otherwise qualitatively inaccurate description of the mesoscale structures. The coarse-grained DPM based on the energy-minimization multi-scale (EMMS) model, or EMMS-DPM, was proposed to reduce the computational cost by several orders while maintaining an accurate description of the mesoscale structures, which paves the way for its engineering applications. Further empowered by the high-efficiency multi-scale DEM software DEMms and the corresponding customized heterogeneous supercomputing facilities with graphics processing units (GPUs), it may even approach realtime simulation of industrial reactors. This short review will introduce the principle of DPM, in particular, EMMS-DPM, and the recent developments in modeling, numerical implementation and application of large-scale DPM which aims to reach industrial scale on one hand and resolves mesoscale structures critical to reaction-transport coupling on the other hand. This review finally prospects on the future developments of DPM in this direction.

Direct catalytic conversion of methane to benzene at non-oxidative condition is considered as one of key reactions for constitution of sustainable carbon-cycling processes, since either biomethane or CO₂-based synthetic methane can serve as its feed source. While this concern may motivate many researchers over the world to make their continuous effort to gain deep insight into the catalytic mechanism of this catalysis system and the essential cause of the catalyst deactivation, successful development of a catalyst with high performance, enhanced coking resistance and long-term operating stability will be the key to its industrial application. Here in this review paper, we demonstrate the high catalytic activity and stability of our two shaped Mo/HZSM-5 catalysts developed respectively for fixed-bed and fluidized-bed operations at severe reaction conditions. Thermodynamically, a possibly high aromatization temperature is required to attain a desired high benzene formation rate, but adopting such a temperature will certainly accelerate coke formation and catalyst deactivation. Therefore, the focus of the catalyst development was laid on finding various effective ways of suppressing coke accumulation and catalyst deactivation at practically required severe reaction conditions, and much effort was made to attain the purpose. As a result, a highly active and selective pelleted Mo/HZSM-5 catalyst has been successfully developed and was stably run in a fixed-bed reactor under cyclic regeneration operation mode over 1000 h. In parallel a binder-free, fluidizable Mo/HZSM-5 catalyst with certain mechanical strength has also been developed and successfully tested in a dual circulating fluidized-bed reactor system to provide a stable benzene yield of about 12% at 1073 K and 3000 ml/g/h space velocity.

As the main contributor to air pollution, lots of volatile organic compounds (VOCs) were emitted into the atmosphere due to the rapid urbanization and industrialization, threatening environmental safety and human health. Catalytic oxidation has been verified as an efficient approach for VOCs elimination from industrial waste gas streams. Owing to the merits of cost-effective and high activity, cobalt-based catalysts have been considered as one of the most promising candidates for VOCs degradation. This review systematically summarized the developments achieved in the design of cobalt-based catalysts for VOCs removal over the past decade. Specifically, the fabrication of single cobalt oxides, cobalt-based binary oxides and cobalt-based composites, as well as the modified cobalt-based oxides by the surface engineering strategies, such as doping technology and acid etching method are coherently reviewed. Subsequently, the corresponding kinetic models and mechanisms are also discussed. Finally, considering the enormous challenges and opportunities in this field, the perspective with respect to future research on cobalt-based catalysts is proposed.

Eucommia ulmoides gum (EUG), main composition is trans-1,4-polyisoprene, is a natural polymer extracted from Eucommia ulmoides plant tissue. Benefiting from the crystallization ability and rubber-plastic duality, it can be applied to a variety of fields, including aerospace, national defense, healthcare, transportation, sports, and construction. Herein, we summarized recent progress in EUG research concerning efficient extraction methods, crystallization characteristics and novel functional EUG materials focused on the relationship between its molecular structure, crystallization behavior, phase structure, and properties. Furthermore, the research and development directions of EUG for the development of its new materials have been outlined.

This review summarized the valuable works on the extraction technologies using pure liquefied dimethyl ether (DME) as the organic solvent. DME is a colorless gas with a slight ether-like fragrance at room temperature and pressure. Due to some special properties, such as the strong ability for extracting organic compounds and water, high extraction rate, cheap price, low extraction temperature, and energy consumption, environmental friendliness, safety, and good compressibility, the application of liquefied DME to the extraction process shows many advantages and has strong potential market competitiveness. On the other hand, the drawbacks of liquefied DME extraction technology were also revealed, mainly on fire hazards, solvent loss, and lack of large-scale application. Furthermore, the previous studies on the application of liquefied DME extraction technology were divided into three parts based on the extracts (water, lipid/oil, and specific ingredients) and listed one by one. The research of the liquefied DME extraction process is still in development. In the future, it is expected that this technology can be continuously improved and optimized in both lab and industrial scales, together with the extension of its application range to more various natural resources.

The plasmonic Ag nanoparticles (NPs) loaded g-C₃N₄ photocatalysts (Ag/C₃N₄) were successfully prepared via a conventional procedure. The fully characterized Ag/C₃N₄ photocatalysts exhibited excellent stability and greatly enhanced visible light-driven photocatalytic performance both in the degradation of methyl orange (MO) and H₂ evolution from water splitting. The 1.0 wt% Ag/C₃N₄ allowed the highest reaction rate of 0.0294 min⁻¹ to be obtained in the MO degradation, which is about 2.3 times higher than the reaction rate of g-C₃N₄ alone of 0.0129 min⁻¹. Furthermore, the optimum H₂ evolution and the k value attained 20 µmol and 1.573 h⁻¹, respectively, after 12 h of visible light irradiation. The surface plasmon resonance effect of Ag NPs and the charge transfer between the two components of the photocatalyst, strongly promote generation of photoinduced charge carriers while suppressing their recombination. These factors are held responsible for the enhanced visible light photocatalytic performance of Ag/C₃N₄. Our methodology will provide guidance for the design and synthesis of plasmon-enhanced visible light photocatalysts derived from Ag NPs and g-C₃N₄ and their applications in environmental remediation and green energy development.

The Paris Agreement has set the goal of carbon neutrality to cope with global climate change. China has pledged to achieve carbon neutrality by 2060, which will strategically change everything in our society. As the main source of carbon emissions, the consumption of fossil energy is the most profoundly affected by carbon neutrality. This work presents an analysis of how China can achieve its goal of carbon neutrality based on its status of fossil energy utilization. The significance of transforming fossils from energy to resource utilization in the future is addressed, while the development direction and key technologies are discussed.

Shale oil resources have proven to be quickly producible in large quantities and have recently revolutionized the oil and gas industry. The oil content in a shale oil formation includes free oil contained in pores and trapped oil in the organic material called kerogen. The latter can represent a significant portion of the total oil and yet production of shale oil currently targets only the free oil rather than the trapped oil in kerogen. Shale oil reservoirs also have a substantial capacity to store CO₂ by dissolving it in kerogen. In this paper, recent progress in the research of CO₂-kerogen interaction and its applications in CO₂ enhanced oil recovery and carbon sequestration in shale oil reservoirs are reviewed. The relevant topics reviewed for this relatively new area include characterization of organic matter, supercritical CO₂ extraction of oil in shale, experimental and simulation study of CO₂-hydrocarbons counter-current diffusion in organic matter, recovery of oil in kerogen during CO₂ huff ‘n’ puff process, and changes in microstructure of shale caused by CO₂-kerogen interaction. The results presented in this paper show that at reservoir conditions, supercritical CO₂ can spontaneously replace the hydrocarbons from the organic matter of shale formations. This mass transfer process is the key to releasing organic oil saturation and maximizing the capacity of carbon storage of a shale oil reservoir. It also presents a concern of the structure change of organic materials for long term CO₂ sequestration with shale or mudstone as the sealing rocks.