Effects Of Carbonization Conditions Research Articles

Effect of carbonization conditions on microstructural properties of isotropic coal tar pitch-based general-purpose carbon fibers

The microstructures of carbon fibers can be significantly modified by understanding the carbonization conditions which improves the properties of fibers. The carbonization is a complex process of converting pitch fibers into carbon fibers through the evolution of gases and arrangement of molecules by polymerization reactions. Hence, the present study focuses on the synthesis of isotropic pitch-based carbon fibers and the investigation of microstructural properties with varying carbonization conditions at 1000 °C. The isotropic pitch is derived from coal-tar pitch through the utilization of a vacuum distillation technique. Various properties of isotropic pitch are studied to determine the flowability and optimum temperature range for melt-spinning into fibers. Subsequently, the stabilization process is conducted in an open atmosphere to retain fibers shape by introducing oxygen-containing functional groups. Time-dependent carbonization parameters such as heating rate and holding/soaking periods are used to optimize the conditions that yield superior microstructural properties. This research reveals that slower heating rates enhance the crystallite sizes while reducing defects. Conversely, longer holding times at carbonization temperature showed adverse effects on the microstructural properties. To assess microstructural, thermal and physical properties of the pitch and fibers, various characterizations are performed, including DSC, TGA, rheology, FTIR, XPS, Raman, XRD, and SEM.

Centrifugally Spun PVA/PVP Based B, N, F Doped Carbon Nanofiber Electrodes for Sodium Ion Batteries.

Owing to their high electrical conductivity, high surface area, low density, high thermal stability, and chemical stability, carbon nanofibers have been used in many fields, including energy storage, electromagnetic shielding, filtering, composites, sensors, and tissue engineering. Considering the environmental impact of petroleum-based polymers, it is vital to fabricate carbon nanofibers from environmentally-friendly materials using fast and safe techniques. PVA/PVP nanofibers were fabricated via centrifugal spinning and the effects of variations in the PVP content on the morphology and thermal properties of PVA/PVP-blend nanofibers were studied using SEM and DSC analyses. Moreover, the effects of carbonization conditions, including stabilization time, stabilization temperature, carbonization time, and carbonization temperature on the morphology and carbon yield, were investigated. Centrifugally spun PVA/PVP-based carbon nanofiber electrodes with an average fiber diameter around 300 nm are reported here for the first time. Furthermore, centrifugally spun PVA/PVP-based B, N, F-doped carbon nanofibers were fabricated by combining centrifugal spinning and heat treatment. Through B, N, F doping, CNFs demonstrated a high reversible capacity of more than 150 mAh/g in 200 cycles with stable cycling performance.

MoS2-Decorated Graphene@porous Carbon Nanofiber Anodes via Centrifugal Spinning.

Sodium-ion batteries (SIBs) are promising alternatives to lithium-ion batteries as green energy storage devices because of their similar working principles and the abundance of low-cost sodium resources. Nanostructured carbon materials are attracting great interest as high-performance anodes for SIBs. Herein, a simple and fast technique to prepare carbon nanofibers (CNFs) is presented, and the effects of carbonization conditions on the morphology and electrochemical properties of CNF anodes in Li- and Na-ion batteries are investigated. Porous CNFs containing graphene were fabricated via centrifugal spinning, and MoS2 were decorated on graphene-included porous CNFs via hydrothermal synthesis. The effect of MoS2 on the morphology and the electrode performance was examined in detail. The results showed that the combination of centrifugal spinning, hydrothermal synthesis, and heat treatment is an efficient way to fabricate high-performance electrodes for rechargeable batteries. Furthermore, CNFs fabricated at a carbonization temperature of 800 °C delivered the highest capacity, and the addition of MoS2 improved the reversible capacity up to 860 mAh/g and 455 mAh/g for Li- and Na-ion batteries, respectively. A specific capacity of over 380 mAh/g was observed even at a high current density of 1 A/g. Centrifugal spinning and hydrothermal synthesis allowed for the fabrication of high-performance electrodes for sodium ion batteries.

Structural control of a novel hierarchical porous carbon material and its adsorption properties

Novel hierarchical porous carbon materials (HPCs) were fabricated via a reactive template-induced in situ hypercrosslinking procedure. The effects of carbonization conditions on the microstructure and morphology of HPCs were investigated, and the adsorption of methylene blue (MB) on HPCs was explored. The as-prepared HPCs has a hierarchical micro-, meso- and macropore structure, which results from the overlap of hollow nanospheres possessing microporous shells and macroporous cavities. The carbonization temperature, carbonization time and carbonization heating rate played important roles in tailoring the nanostructures of HPCs. The BET specific surface area and micropore specific surface area can reach 2388 m2 g−1 and 1892 m2 g−1, respectively. Benefitting from the well-developed pore structure, the MB removal efficiency can exceed 99% under optimized conditions. The adsorption kinetics and thermodynamics can be well described by a pseudo-second-order model and Langmuir model, respectively. Furthermore, such adsorption was characterized by a spontaneous endothermic process.

High Surface Area Nanoporous Activated Carbons Materials from Areca catechu Nut with Excellent Iodine and Methylene Blue Adsorption

Nanoporous carbon materials from biomass exhibit a high surface area due to well-defined pore structures. Therefore, they have been extensively used in separation and purification technologies as efficient adsorbents. Here, we report the iodine and methylene blue adsorption properties of the hierarchically porous carbon materials prepared from Areca catechu nut. The preparation method involves the phosphoric acid (H3PO4) activation of the Areca catechu nut powder. The effects of carbonization conditions (mixing ratio with H3PO4, carbonization time, and carbonization temperature) on the textural properties and surface functional groups were studied. The optimum textural properties were obtained at a mixing ratio of 1:1, carbonized for 3 h at 400 °C, and the sample achieved a high specific surface area of 2132.1 m2 g−1 and a large pore volume of 3.426 cm3 g−1, respectively. The prepared materials have amorphous carbon structures and contain oxygenated surface functional groups. Due to the well-defined micro-and mesopore structures with the high surface area and large pore volume, the optimal sample showed excellent iodine and methylene blue adsorption. The iodine number and methylene blue values were ca. 888 mg g−1 and 369 mg g−1, respectively. The batch adsorption studies of methylene dye were affected by pH, adsorbent dose, contact time, and initial concentration. The optimum parameters for the methylene blue adsorption were in alkaline pH, adsorbent dose of 2.8 g L−1, and contact time of 180 min. Equilibrium data could be best represented by the Langmuir isotherm model with a monolayer adsorption capacity of 333.3 mg g−1. Thus, our results demonstrate that the Areca catechu nut has considerable potential as the novel precursor material for the scalable production of high surface area hierarchically porous carbon materials that are essential in removing organic dyes from water.

Fabrication of porous tubular carbon fibers from the fruits of Platanus orientalis and their high oil adsorption properties

Faced with the stark challenge of global oil spills, development of clean absorbent materials is crucial. In this paper, the plant fibers extracted from the waste Platanus orientalis are transformed by vacuum carbonization method, and the fibers with micron-size cavities and porous pipe walls are obtained simply and cheaply. The fibers exhibit high oil adsorption capacity. The effects of carbonization conditions, adsorption temperature and time on adsorption capacity are systematically investigated. Specific surface area of F900–10 obtained by vacuum carbonization at 900 °C for 10 h is 702.44 m2/g. It has the best adsorption performance and can absorb 71.72–172.37 times of its own weight. Meanwhile, oil can be removed quickly by simple extrusion, and the oil removal rate reaches 63.18–95.67%. The adsorption sites of the tubular carbon fibers to the oil include micron-scale cavities, the physical cross-linking network that overlaps between the fibers, and the nano-scale pores on the tube wall. Further, the practicability of F900–10 is tested by simulating oil leakage in diverse environments, and its removal efficiency ranged from high to low in seawater, glass, soil and sand. High adsorption capacity and significant oil removal rate make F900–10 a promising oil adsorption material with high potential value.

Effects of carbonization conditions on the microporous structure and high-pressure methane adsorption behavior of glucose-derived graphene

A simple, promising, environmentally friendly, and high yield technique to synthesize high specific surface area (SSA) and porous graphene-like materials from glucose precursor through carbonization and controlled chemical iron chloride (FeCl3) activation was demonstrated. Designing this nanoporous graphene-based adsorbent with high SSA, abundant micropore volume, tunable pore size distribution, and high adsorption capacity, is crucial in order to deal with the demands of large-scale reversible natural gas storage applications. Raman spectroscopy, BET method of analysis, and N2 adsorption/desorption measurements at 196 °C were adopted to evaluate the structural and textural properties of the resultant glucose derived-graphene (gluGr) samples. The effects of different carbonization conditions, such as the inert environments (argon, helium, and argon) and temperatures (700, 800, 900, and 1,000 °C), have been studied. A glucose-derived graphene carbonized under nitrogen environment at 700 °C (NGr700) with highly interconnected network of micropores and mesopores and large SSA (767 m2/g) exhibited excellent methane (CH4) storage property with exceptionally high adsorption capacity, superior to other glucose-derived graphene (gluGr) samples. A maximum volumetric capacity up to 42.08 cm3/g was obtained from CH4 adsorption isotherm at 25 °C and 35 bar. Note that the adsorption performance of the CH4 is highly associated with the SSA and microporosity of the gluGr samples, especially NGr700 that was successfully synthesized by FeCl3 activation under N2 environment.

Carbon Fibers from Lignin–Cellulose Precursors: Effect of Carbonization Conditions

Carbon Fibers from Lignin–Cellulose Precursors: Effect of Carbonization Conditions

Effects of Carbonization Conditions on Structure and Gas Adsorption of Carbon Membranes Derived from Polyvinyl Chloride

AbstractCarbon membranes were fabricated through the pre‐oxidation and pyrolysis of polyvinyl chloride (PVC). Their chemical composition and structure morphology were characterized using FTIR, SEM and XRD; their CO2 and N2 adsorption isotherms were measured at 25 °C. The experimental results showed that heating rate and holding time have great influences on the pore structure during the pre‐oxidation process as well as the carbonization process. The pore structure of the carbon membrane is also influenced by carbonization temperature. The carbon membrane obtained at 700 °C has the largest CO2 adsorption capacity of 1.45 mmol/g at 101 kPa. The carbon membrane prepared at heating rate of 3 °C/min and holding time of 0.5 h at 800 °C displayed an excellent adsorption selectivity of CO2 over N2 evidenced by the fact that its CO2 adsorption capacity could reach 1.1 mmol/g and while it does not significantly adsorb N2.

The effects of carbonization conditions on electrochemical performance of attapulgite-based anode material for lithium-ion batteries

In this work, attapulgite-based anode materials with different polyacrylonitrile contents were fabricated. The effect of polyacrylonitrile contents on electrochemical performances of the anode materials was systematically investigated. The optimal attapulgite/polyacrylonitrile ratio for the anode material was selected via comparing with electrochemical specific capacity at the same current density. It was shown that the specific capacity of the sample with 20 wt% polyacrylonitrile could reach a maximum value of 446.5 mAh g−1 at the same current density. Furthermore, the effect of carbonization temperatures on electrochemical properties of the anode materials with 20 wt% polyacrylonitrile was investigated. The structural features of the carbonized samples were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Brunauer–Emmett–Teller, field emission scanning electron microscopy, transmission electron microscopy, energy dispersive spectrometer and X-ray photoelectron spectroscopy. The discharge specific capacity of the anode material carbonized at 800 °C reached the maximum value of 446.5 mAh g−1 at a current density of 0.1 A g−1 at the 50th cycle. The coulombic efficiency of the AT-based anode material carbonized at 800 °C was 99.8% at the current density of 0.5 A g−1 at the 300th cycle. The anode material carbonized at 800 °C with a mass loading of 0.85 mg cm−2 had excellent electrochemical conductivity and rate capability.

Preparation of hydrothermal carbon acid catalyst from defatted rice bran

In this study, the effects of carbonization conditions: temperature (180–250 °C) and time (1–8 h) on the yield and the chemical characteristics of hydrothermal carbon derived from defatted rice bran (HTCDRB) were determined. The morphological and chemical characteristics of the sulfonated HTCDRB catalyst were also examined. In addition, the stability of the catalyst was evaluated based on the amounts of biomass conversion products (5-hydroxymethylfurfural (HMF), furfural, levulinic acid and formic acid) leached into water at a specified biomass conversion condition. Since no HMF and furfural, and only small amounts of levulinic acid (1.75 wt.%), and formic acid (0.42 wt.%), were leached from the catalyst synthesized from HTCDRB prepared at the carbonization condition of 220 °C for 3 h, this condition was suggested to be a suitable carbonization condition. Despite having similar structural and chemical characteristics, the leaching test suggested that the DRB-based hydrothermal carbon catalyst was found to be more stable than the glucose-based hydrothermal carbon catalyst, prepared at the same condition. The catalytic activity for cellulose hydrolysis of the catalyst was higher than that of the commercial Amberlyst 16 WET catalyst.

Effect of carbonization conditions on CO2 gasification reactivity of biocarbon

Substituting fossil reductants with biocarbon is a promising way for reducing greenhouse gas emissions and increase sustainability of the metallurgical industry. Biocarbon can be produced from a wide range of raw biomass materials and carbonization conditions. Studies on the properties of biomass biocarbon are critical for further efficient utilization of the biocarbon in metallurgical industries. The purpose of this study was to study the impact of pyrolysis temperature and calcination treatment on properties of woody biomass biocarbon focusing on gasification reactivity under CO2 atmosphere. The experimental work was carried out using Norway spruce biocarbon produced at two different carbonization temperatures (650 and 800 °C). In addition, pine wood biocarbon produced at 650 °C was also gasified for comparison purpose. Considering the possible negative effects of the volatile content on metallurgical processes, the studied biocarbon samples were also calcined at 1000 °C for 1 hour to eliminate the volatile matters. Both the uncalcined and calcined biocarbons were gasified in a furnace setup at 850 °C under CO2 atmosphere with continuous monitoring of the weight loss. The results showed that the carbonization temperature has evident effects on CO2 gasification reactivity of the studied biocarbons. The calcination treatment lowered the CO2 gasification reactivity of the studied biocarbons. This is due to the higher temperature applied for the calcination compared to the carbonization, and additionally it might be due to loss of catalytic inorganic elements and structure reordering of the carbon matrix during the calcination that is accompanied by loss of active carbon sites. From this point view, calcination is an option to tune properties (i.e., remove volatiles, increase fixed carbon content, reduce reactivity etc.) of biocarbon, to better fit the requirements of metallurgical processes. In addition, different gasification behaviors were observed for the studied spruce and pine biocarbons produced under the same conditions. This is mainly attributed to the different nature of them, physical and chemical properties as well as the amount and composition of ash forming elements.

Matrimid-based carbon tubular membrane: Effect of carbonization environment

Among gas separation materials, carbon membrane exhibits the most interesting performance in terms of selectivity, stability, and gas permeance. By controlling and optimizing carbonization environment, excellent gas separation performances can be achieved. In this study, tubular supported carbon membrane was prepared using Matrimid as polymeric precursor. In order to produce high performance carbon membrane, the effect of carbonization conditions on the gas permeation properties was investigated. The polymer solution was coated on the surface of the tubular support by using dip-coating method. Carbon membranes were fabricated by heat treatment process under controlled carbonization environments; Ar or N2. Pure gas permeation tests were performed using CO2, CH4, and N2 at room temperature with pressure 8bar. Based on the results, the highest CO2/CH4 and selectivity of 87.34 and CO2/N2 selectivity of 79.60 were obtained by carbon membrane carbonized under Ar gas. Despite the higher carbonization temperature, the carbonization under Ar created more permeable pores as compared to N2 environment.

Synthesis and characterizations of nanoporous carbon derived from Lapsi (Choerospondias axillaris) seed: Effect of carbonization conditions

We report a facile synthesis of nanoporous activated carbons (NACs) derived from Lapsi (Choerospondias axillaris) seed powder (LSP). LSP and sodium hydroxide (NaOH) are mixed in 1:1 ratio by wt. and carbonized at 400°C for different time (3, 4, and 5h) and at different temperature (400, 500, 600, and 700°C) for 3h under a constant flow of ultrapure nitrogen gas. The effect of the conditions during the preparation on the structures and properties of NACs is investigated carefully. Fourier transform infrared spectroscopy (FT-IR) show the presence of several functional groups (e.g., hydroxyl, carbonyl, and carboxyl groups) on the carbon surface. Irrespective of the carbonization conditions, both D and G bands are clearly observed in Raman scattering spectra. It is found that the increase in carbonization time significantly increases the G/D bands ratio, indicating an enhancement in the graphitic character. The NACs prepared by carbonization at 400°C for 3h have the highest surface area (over 1000m2g−1) and show high adsorption efficiency in removing methylene blue (MB) from aqueous solution (around 200mgg−1).

Effects of carbonization conditions on the properties of coal-based microfiltration carbon membranes

Carbon membranes, a novel porous inorganic membrane, have considerable potential applications in many industrial fields owing to their better stability in aggressive and adverse environments. However, the high cost of precursor materials has hampered their wide applications on commercial scale. In this study, coal, a cheap material, is used to prepare the tubular microfiltration carbon membranes. The effects of carbonization conditions on the properties of coal-based carbon membrane were investigated by the variation of the weight loss, shrinkage ratio of tube size and pore structure characteristics during carbonization. The results show that carbonization conditions greatly affect the properties of coal-based carbon membranes. The carbon membranes carbonized in the inert gases have more “open” porous structure and high gas flux compared to those carbonized in vacuum which makes the carbon membrane possess smaller pores and low gas flux. The carbonization temperature plays an important role in the determination of the pore structure and densification of carbon matrix. At the temperature below 600°C, the pore structure and carbon matrix of carbon membrane are formed with more than 95% of the total weight loss and only 48% of the total size shrinkage ratio. The matrix of carbon membrane gets more compact with the temperature increasing from 600°C to 900°C, in which the size shrinkage ratio is up to 52% with only 5% of the total weight loss. The low heating rate should favor the preparation of the carbon membranes with small average pore size and narrow pore size distribution, and the high gas flow rate can produce the carbon membranes with large average pore size and high porosity.

Preparation of activated carbon cloths from viscous rayon: Part III. Effect of carbonization on CO 2 activation

Viscous rayon cloth was carbonized under different experimental conditions The final temperature was 850°C, using heating rates of 0.5, 1, 3 and 5°C min −1; an additional char was obtained at 5°C min −1 but introducing an isothermal stage at 230°C a temperature near the pyrolytic decomposition of the precursor. A sixth char was prepared by treating the precursor in air at 230°C for 2.7 h before carbonization at 5°C min −1 up to 850°C. All chars were activated under a flow of carbon dioxide at 825°C. The effect of carbonization conditions on the porosity, mechanical strength and oxygen surface groups of resultant activated carbon cloth is analyzed, in order to optimize the properties of the final product.

Mechanical Properties of Acacia and Eucalyptus Wood Chars

In the present investigation the effects of carbonization conditions (temperature and heating rate) on the mechanical properties (such as crushing and impact strengths and shatter index) of acacia and eucalyptus wood chars have been determined. The crushing and impact strengths of both the acacia and eucalyptus wood chars (made by slow carbonization) decreased with increase of preparation temperature up to 600 degrees C, followed by an increase thereafter. These wood chars showed a continuous increase in shatter index values with carbonization temperature. In contrast to slow carbonization (heating rate 4 degrees C min -1), rapid carbonization (heating rate 30 degrees C min -1) yielded chars of lower crushing strengths. Slowly carbonized eucalyptus wood gave chars of superior crushing and impact strengths than those produced from acacia wood under the same carbonization conditions. The crushing and impact strengths of these wood chars, in general, have shown an increase with increase in their apparent density. The crushing strength of cubic-shaped wood char decreased with increase in size.

97/02802 Effect of carbonization conditions and metallic catalysts on micropore structure of coal chars

97/02802 Effect of carbonization conditions and metallic catalysts on micropore structure of coal chars

Influence of carbonization conditions and wood species on carbon dioxide reactivity of resultant wood char powder

Carbon dioxide reactivities of powdered samples of Acacia and Eucalyptus wood chars were measured thermogravimetrically at 900°C and the effects of carbonization conditions (temperature, heating rate and soaking time) and wood species were determined. The results showed that the reactivity decreased with increasing carbonization temperature and soaking time. Chars prepared under rapid carbonization (heating rate: 30°C min −1) were found to be more reactive than the chars produced by slow carbonization (heating rate: 4°C min −1). In comparison to Eucalyptus wood chars, the Acacia wood chars exhibited higher reactivity.

The effect of carbonization conditions on the properties of rayon-based carbon fibres

The effect of carbonization temperature on the properties of prewoven carbon fibre made from a rayon precursor is examined. Bulk composition is contrasted with surface elemental analysis (XPS) which shows that low carbonization temperatures (2300F, 1260C) produce a fibre with up to 15 and 5 at.% of oxygen and sodium respectively on the surface. At higher firing temperatures (up to 3000, 1649 C), the surface O and Na levels are significantly reduced and the measured fibre surface area declines from 50 m2 g-1 to under 5 ml g-'. Atomic force microscopy (AFM) was used to examine the surface detail of fibres at magnifications over 250000 times. AFM micrographs reveal that the fibre surface after carbonization at low temperatures is covered with a crust believed to be the char residue from tars released during the precarbonization stage. Surface analysis by Auger spectroscopy has confirmed the high oxygen and sodium content of the char material. Use of higher carbonization temperatures results in fibre surface properties which are generally regarded as preferable for use in ablative applications.