Search Results (16)

In this study, the characteristics of coal sorbents obtained by the activation of coke fines in an atmosphere of a mixture of gases CO₂ and H₂O were studied. The experiment was conducted at various temperatures (700–900 °C), activation time (60–180 min), and constant CO₂ supply rate (0.5 L/min). The main parameters such as tinder, ash content, bulk density, sorption capacity, total pore volume, and specific surface area were analyzed to assess the efficiency of the process. The results showed that samples of sorbents obtained at a temperature of 800 °C and an activation time of 120 min have the highest sorption capacity for iodine (up to 64.77%). The specific surface area of the obtained carbon sorbents was ~432.6 m²/g. It was found that an increase in temperature to 900 °C leads to a decrease in sorption characteristics, which may be due to partial destruction of the porous structure of the material. It was also found that the duration of activation contributes to an increase in burn-off and ash content, which had an effect on sorption properties. Based on the data obtained, optimal conditions for the production of carbon sorbents have been established and a process model has been developed. Full article

CO₂ capture from the flue gas is a promising approach to mitigate global warming. However, regulating the carbon-based adsorbent in terms of textural and surface modification is still a challenge. To overcome this issue, the present study depicts the development of cost-effective and high-performance CO₂ adsorbents derived from petroleum coke, an industrial by-product, using a two-step process involving thiourea modification and KOH activation. A series of N,S-codoped porous carbons was synthesized by varying activation temperatures and KOH quantity. The optimized sample exhibited a high specific surface area of 1088 m²/g, a narrow micropore volume of 0.52 cm³/g, and considerable heteroatom doping (1.57 at.% nitrogen and 0.19 at.% sulfur). The as-prepared adsorbent achieved a CO₂ adsorption capacity of 3.69 and 5.08 mmol/g at 1 bar, 25 °C and 0 °C, respectively, along with a CO₂/N₂ selectivity of 17. Adsorption kinetics showed 90% of equilibrium uptake was achieved within 5 min, while cyclic studies revealed excellent stability with 97% capacity retention after five cycles. Thermodynamic analysis indicated moderate isosteric heat of adsorption (Q_st) values ranging from 18 to 47 kJ/mol, ensuring both strong adsorption and efficient desorption. These findings highlight the potential of petroleum coke-derived porous carbons for sustainable and efficient CO₂ capture applications. Full article

Chloride ions readily react with organic matter and other ions, resulting in the formation of disinfection by-products (DBPs) that exhibit heightened levels of toxicity, carcinogenicity, and mutagenicity. This study creatively employed waste walnut shells as self-templates and low-cost magnesium bicarbonate as a rigid template to successfully synthesize multifunctional porous carbon derived from walnut shells. Employing a series of characterization techniques, it was ascertained that the porous carbon material (WSC/Mg) synthesized via the dual-template method exhibited a distinct layered microscopic surface structure, with a predominance of C and O elements on the surface. The material displayed a high degree of graphitization, significant specific surface area, and abundant oxygen-containing surface functional groups. The incorporation of magnesium bicarbonate as a hard template improved the structure of the walnut shell porous carbon, resulting in a significant enhancement in mass transfer efficiency for the target product on the adsorbent and a substantial improvement in removal efficiency. In comparison with walnut shell-derived carbon using only self-templating, WSC/Mg exhibited a 17.26-fold increase in adsorption capacity for 2,4-dichlorophenol. Furthermore, even after four adsorption–desorption cycles, WSC/Mg-12 maintained an adsorption efficiency above 90%. It is remarkable that WSC/Mg-12 demonstrated exceptional resistance to interference from natural organic matter and pH variations. Moreover, the adsorbed saturated WSC/Mg-12 effectively treated real coke wastewater, resulting in an 80% color removal rate, 20% COD removal rate, and 15% ammonia nitrogen removal rate. In conclusion, this study presents an innovative approach for cost-effective and versatile porous carbon materials with extensive applications in water environment purification and biomass utilization. Full article

A Co-doped porous carbon was successfully fabricated by a facile carbonizing procedure using coal hydrogasification semi-coke (SC) as the carbon and cobalt nitrate as the magnetic precursors, respectively. The mass ratio of the precursors was changed to regulate the microwave absorption (MA) capabilities. The favorable MA capabilities are a result of a synergistic interaction be-tween the dielectric loss from the carbon framework, the magnetic loss from nano-sized Co particles, and multiple scattering from the residual pores. At a thickness of 4.0 mm, the Co/C composite showed the lowest reflection loss of −33.45 dB when the initial mass ratio of cobalt nitrate and SC was 1:1. The effective absorbing bandwidth (EAB) could achieve 3.5 GHz at 2 mm thickness. This work not only opens up a new avenue for the facile fabrication of dielectric and magnetic loss combinations and their structural design, but it also creates a new route for the high value-added exploitation of SC. Full article

This comprehensive review addresses the need for sustainable and efficient energy storage technologies against escalating global energy demand and environmental concerns. It explores the innovative utilization of waste materials from oil refineries and coal processing industries as precursors for carbon-based electrodes in next-generation energy storage systems, including batteries and supercapacitors. These waste-derived carbon materials, such as semi-coke, coal gasification fine ash, coal tar pitch, petroleum coke, and petroleum vacuum residue, offer a promising alternative to conventional electrode materials. They present an optimal balance of high carbon content and enhanced electrochemical properties while promoting environmental sustainability through effectively repurposing waste materials from coal and hydrocarbon industries. This review systematically examines recent advancements in fabricating and applying waste-derived carbon-based electrodes. It delves into the methodologies for converting industrial by-products into high-quality carbon electrodes, with a particular emphasis on carbonization and activation processes tailored to enhance the electrochemical performance of the derived materials. Key findings indicate that while higher carbonization temperatures may impede the development of a porous structure, using KOH as an activating agent has proven effective in developing mesoporous structures conducive to ion transport and storage. Moreover, incorporating heteroatom doping (with elements such as sulfur, potassium, and nitrogen) has shown promise in enhancing surface interactions and facilitating the diffusion process through increased availability of active sites, thereby demonstrating the potential for improved storage capabilities. The electrochemical performance of these waste-derived carbon materials is evaluated across various configurations and electrolytes. Challenges and future directions are identified, highlighting the need for a deeper understanding of the microstructural characteristics that influence electrochemical performance and advocating for interdisciplinary research to achieve precise control over material properties. This review contributes to advancing electrode material technology and promotes environmental sustainability by repurposing industrial waste into valuable resources for energy storage. It underscores the potential of waste-derived carbon materials in sustainably meeting global energy storage demands. Full article

A Computational Fluid Dynamic study was carried out to match the measured outer ash deposition rates associated with the combustion of petroleum coke (PC)–natural gas in AIR and O₂/CO₂ (70/30 vol%, OXY70). The fly ash PSD associated with high-fixed-carbon, non-porous fuel was estimated using a shrinking sphere burnout model and employed in conjunction with particle kinetic energy (PKE), particle viscosity (µ_P), and a critical Weber-number-based capture criterion. Deposition rate predictions were sensitive to the fly ash composition employed for estimating µ_P due to the significant enrichment of Fe in the deposits. Predictions were insensitive to the specific µ_P model formulation employed or whether the V₂O₅ in the ash was assumed to play the role of a glass former or a glass modifier. OXY70 scenario impaction rates were significantly lower than the measured deposition rates when the fly ash PSD associated with the AIR scenario was employed in the calculations. This necessitated an ad hoc modification of the OXY70 fly ash PSD to a coarser range to match the measurements and attributing it to agglomeration resulting from longer residence times and higher temperatures. This shift in PSD was in line with AIR and OXY70 fly ash PSD measurements reported previously. Full article

The choice of precursor and simple synthesis techniques have decisive roles in the viable production and commercialization of carbon products. The intense demand for developing high-purity carbon nanomaterials through inexpensive techniques has promoted the usage of fossil derivatives as a feasible source of carbon. In this study, Vietnamese-coal-derived porous carbon (PC) was used to fabricate coal-derived porous carbon nanomaterials (CDPCs) using the modified Hummers method. The resulting porous carbon nanomaterials achieved a nanoscale structure with an average pore size ranging from 3 to 10 nm. The findings indicate that CDPC exhibits well-developed micropores and mesopores. The presence of macropores and mesopores not only facilitates the complete immersion of the material in the electrolyte but also effectively shortens the ion diffusion pathways. CDPC boasts a high carbon content, constituting 80.88% by weight. Electrochemical impedance spectroscopy (EIS) Nyquist plot of electrodes made from CDPC showed good conductivity value with low charge-transfer resistance. This electrode worked well and stably with capacitance retention of 74.7% after 1000 cycles. The CDPC specific capacitance reached 236 F/g under a current density of 0.1 A using the constant current discharge method and then decreased as the current density increased. Based on the results of the electrochemical properties of the materials, the energy storage capacity of the CDPC material was good and stable. This investigation presents an eco-friendly methodology for the judicious utilization of coal in energy storage applications, specifically as electrodes for supercapacitors and anodes for Li-ion batteries. Full article

The gasification kinetics of semi-coke are an important research topic in the gasification process of semi-coke. The evolution of the pore structure is one of the most important factors affecting the gasification rate of semi-coke. In this paper, the pore fractal growth model was established based on the principle of pore fractal growth and the Sierpinski sponge structure. Three kinds of semi-coke raw materials were used to prepare porous carbon with different degrees of gasification. Combined with the TG curves of raw materials, the gasification kinetics based on the fractal model were verified. The curves of the gasification reaction rate and the specific surface area as a function of carbon conversion were consistent with the random pore model and experimental data, which verified the feasibility of the model. The pore fractal dynamic model could predict the change in the pore structure with carbon conversion during semi-coke gasification, so as to reveal the kinetic law of carbon gasification. Full article

The possibility of obtaining effective coal sorbents from a low-liquid product of coke chemical production—coke fines—has been studied. To obtain a coal sorbent, coke fines with a size of ≤10 mm were crushed and sieved to obtain a fraction of 2–5 mm. The resulting fraction was activated in a specially designed reactor at 850 °C with steam treatment. Activation was carried out at different durations of the process: 60, 90, and 120 min. It was found that the sample obtained with a process duration of 120 min has the best indicator for the ability to remove phenol from aqueous solutions (74.94 mg/g) and methylene blue (145 mg/g). When cleaning tap water with the resulting carbon sorbent, there is a decrease in the content of calcium, sulfates, and bicarbonate and a decrease in total mineralization. Obtained activated carbon was studied by scanning electron microscopy, low-temperature nitrogen adsorption (BET), and FTIR spectroscopy. It was found that the resulting activated carbon has a porous structure consisting of meso- and macropores, and the specific surface value was ~301 m²/g. The presence of high-intensity absorption bands corresponding to acid functional groups has also been established. Full article

As a modification of the conventional blast furnace (BF), the top gas recycling-oxygen blast furnace (TGR-OBF) has been continuously studied in the context of the technological transformation of low-carbon metallurgy. As it has a set of new gas inlets in the stack and changes the blast operation system in the hearth, the pressure drop and the in-furnace gas flow are the primary problems to be solved in the TGR-OBF’s industrialization. In this paper, a two-dimensional model of a whole blast furnace, based on a softening-and-melting experiment and porous-medium theory, is established. The in-furnace pressure drop and the gas velocity with different oxygen concentrations and tuyere heights are studied. The results show that the suitable height of the stack tuyere is the same as that of the elevation as the cohesive zone inside the furnace. With the gradual increase in oxygen enrichment, the permeability of the cohesive ore layer (COL) increases, while the gas flow through the coke layer (CL) decreases gradually up to 10%. The simulation results provide a theoretical basis for the TGR-OBF to reduce the coke rate and keep the pressure drop from increasing, or even to enable it to decrease. Full article

This review comprehensively examines biochar, an essential material in an era of climate change for reducing carbon dioxide (CO₂) emissions into the atmosphere. It is inconspicuous, black, lightweight, and very porous, and is produced through the thermal conversion of biomass. Our literature review highlights biochar’s expansive application possibilities. Firstly, its potential to improve soil quality and sequester CO₂ has been examined, as well as its utilization in iron and steel manufacturing to minimize the quantity of coke and ultimately reduce CO₂ emissions. In industrial manufacturing, the complete elimination of coke can promote environmental neutrality, which is achieved using biochar from biomass for its extrusion. Furthermore, biochar is becoming increasingly significant in modern energy storage technologies and as an important additive in Pickering emulsions, which are also employed in energy storage systems. Additionally, the use of carbon black is a broad topic, and this review illustrates where it can be successfully utilized, especially in environmentally sensitive areas. Full article

Developing low-temperature nickel-based catalysts with good resistance to coking and sintering for dry reforming of methane (DRM) is of great significance. In this work, Ni (5 wt%) and CeO₂ (5 wt%) were supported on SBA-15 porous material by glycine-assisted impregnation method to obtain Ni-CeO₂/SBA-15-G catalyst. XRD and TEM results showed that the addition of glycine can effectively promote the dispersion of NiO and CeO₂ in the pores of SBA-15. H₂-TPR and XPS results confirmed the formation of stronger metal-support interaction. In addition, after the addition of glycine, the Ni_xCe_1−xO_y solid solution content was increased significantly, meanwhile, the Ce³⁺ concentration was increased from 31% to 49%, accompanied by more oxygen vacancies and generation of active oxygen species. For the above reasons, Ni-CeO₂/SBA-15-G had better catalytic performance in the low-temperature DRM test (20 h, 600 °C) with high GHSV (600,000 mL/g_cat/h), its CH₄ conversion after reaction of 20 h was 2 times that of Ni-CeO₂/SBA-15-C catalyst prepared by a conventional impregnation method. TGA-DTA test also proved that Ni-CeO₂/SBA-15-G almost completely eliminated carbon deposition. The above advantages of the Ni-CeO₂/SBA-15-G catalyst may have originated from the complexation of glycine with metal cations and can prevent them from gathering. Full article

Pet-coke (petroleum coke) is identified as a carbon-rich and black-colored solid. Despite the environmental risks posed by the exploitation of pet-coke, it is mostly applied as a boiling and combusting fuel in power generation, and cement production plants. It is considered as a promising replacement for coal power plants because of its higher heating value, carbon content, and low ash. A computational fluid dynamics (CFD) computational model of methane steam reforming was developed in this research. The hydrogen production system is composed from a pet-coke burner and a catalyst bed reactor. The heat released, produced by the pet-coke combustion, was utilized for convective and radiative heating of the catalyst bed for maintaining the steam reforming reaction of methane into hydrogen and carbon monoxide. This computational algorithm is composed of three steps—simulation of pet-coke combustion by using fire dynamics simulator (FDS) software coupled with thermal structural analysis of the burner lining and a multiphysics computation of the methane steam reforming (MSR) process taking place inside the catalyst bed. The structural analysis of the burner lining was carried out by coupling the solutions of heat conduction equation, Darcy porous media steam flow equation, and structural mechanics equation. In order to validate the gaseous temperature and carbon monoxide mole fraction obtained by FDS calculation, a comparison was carried out with the literature results. The maximal temperature obtained from the combustion simulation was about 1440 °C. The calculated temperature is similar to the temperature reported, which is also close to 1400 °C. The maximal carbon dioxide mole fraction reading was 15.0%. COMSOL multi-physics software solves simultaneously the catalyst media fluid flow, heat, and mass with chemical reaction kinetics transport equations of the methane steam reforming catalyst bed reactor. The methane conversion is about 27%. The steam and the methane decay along the catalyst bed reactor at the same slope. Similar values have been reported in the literature for MSR temperature of 510 °C. The hydrogen mass fraction was increased by 98.4%. Full article

Porous graphite was prepared without the use of template by rapidly heating the carbonization products from mixtures of anthracene, fluorene, and pyrene with a CO₂ laser. Rapid CO₂ laser heating at a rate of 1.8 × 10⁶ °C/s vaporizes out the fluorene-pyrene derived pitch while annealing the anthracene coke. The resulting structure is that of graphite with 100 nm spherical pores. The graphitizablity of the porous material is the same as pure anthracene coke. Transmission electron microscopy revealed that the interfaces between graphitic layers and the pore walls are unimpeded. Traditional furnace annealing does not result in the porous structure as the heating rates are too slow to vaporize out the pitch, thereby illustrating the advantage of fast thermal processing. The resultant porous graphite was prelithiated and used as an anode in lithium ion capacitors. The porous graphite when lithiated had a specific capacity of 200 mAh/g at 100 mA/g. The assembled lithium ion capacitor demonstrated an energy density as high as 75 Wh/kg when cycled between 2.2 V and 4.2 V. Full article

This paper details the characterisation of char obtained by high-temperature pyrolysis of waste macadamia shell biomass and its application as carbon source in iron-carbon alloy production. The obtained char was characterised by ultimate and proximate analysis, X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray photon spectroscopy (XPS), Brunauer-Emmett-Teller (BET) surface area via N₂ isothermal adsorption and scanning electron microscopy (SEM). The results indicated that obtained char is less porous, low in ash content, and high in carbon content. Investigation of iron-carbon alloy formation through carbon dissolution at 1550 °C was carried out using sessile drop method by using obtained char as a carbon source. Rapid carbon pickup by iron was observed during first two minutes of contact and reached a saturation value of ~5.18 wt % of carbon after 30 min. The carbon dissolution rate using macadamia char as a source of carbon was comparatively higher using than other carbonaceous materials such as metallurgical coke, coal chars, and waste compact discs, due to its high percentage of carbon and low ash content. This research shows that macadamia shell waste, which has a low content of ash, is a valuable supplementary carbon source for iron-carbon alloy industries. Full article