Production Of Nanocarbon Research Articles

Understanding the impact of support materials on CoFe2O4 catalyst performance for hydrogen fuel and nanocarbon production via methane decomposition

This study focuses on assessing the performance and durability of three distinct catalysts, namely CoFe2O4/MgO and CoFe2O4/TiO2 and CoFe2O4/Al2O3 in the methane decomposition process. These catalysts were synthesized using a co-precipitation impregnation route. Their catalytic activity of methane decomposition was examined in a fixed-bed reactor at a temperature of 800 °C under atmospheric pressure. Various appropriate analytical techniques were employed to explore the physicochemical characteristics of both the fresh and spent catalysts. The SEM images, XRD and H2-TPR results of fresh catalysts revealed strong dependence on the support type. The XPS results confirm the presence CoFe2O4 species on the surface of supports. The CoFe2O4/MgO catalyst has a higher inversion degree compared with other catalysts as confirmed from Raman results. The methane conversions at the end of the reaction time (300 min) were found to be 66 %, 34 % and 2.48 %, while the rates of hydrogen formation corresponding to these methane conversions are 134.73 × 10−5, 68.25 × 10−5 and 8.80 × 10−5 mol H2 g−1 min−1 for CoFe2O4/MgO and CoFe2O4/TiO2 and CoFe2O4/Al2O3 catalysts, respectively. SEM images verified the existence of filamentous carbon on the surface of the spent CoFe2O4/MgO catalyst, whereas the spent CoFe2O4/TiO2 catalyst showed a mix of carbon chunks and filaments and fluffy carbon over the CoFe2O4/Al2O3 catalyst. Ultimately, the quantity of deposited carbon was significantly associated with catalytic activity, as they were 56, 46 and 4 wt% for the spent CoFe2O4/MgO, CoFe2O4/TiO2 and CoFe2O4/Al2O3 catalysts, respectively.

Nitrocellulose-containing sediment as renewable resource for hydrogen and high-pure carbon production

Nitrocellulose accumulated in sludge accumulators does not undergo any changes and remains explosive for decades but it can be used as initial recourse for H2 and nanocarbon production through biogas. Anaerobic biotransformation of waste with a nitrocellulose content of about 75% with native microflora, consortia of mesophilic or thermophilic microorganisms from industrial bioreactors under various volume loading of microorganisms and temperature conditions has been studied. Stimulation by an additional source of biogenic elements and the development of native microflora made it possible to reduce the concentration of nitrocellulose by 44% at 35 °C in 100 days. With a biocatalyst volume loading of 30% at 35 °C with mesophilic biocatalyst 39% of nitrocellulose (with 50% initial volume loading) was conversed to biogas, at 55 °C with thermophilic biocatalyst-99%. The rate constant of decomposition of nitrocellulose using a thermophilic biocatalyst was 0.0248 day−1, while the half–life of nitrocellulose was 28 days.

Production of Nanocarbon from Local Raw Materials

This research aims at extraction of nanocarbon from local raw materials through a detailed study of its characteristics. The research involves study of thermal properties of fruit kernels (apricots) and walnut kernels, determining the optimal modes of the carbonization process for each type of raw material, developing a method for the synthesis of spherical granules by liquid granulation and determining the optimum concentration of the sulfuric acid solution used in granulation. Analysis of the results on the dynamic sorption of petroleum products showed that maximum sorption is achieved when using a sorbent obtained at 400∘C for 30 minutes. Temperature regimes have been optimized for obtaining sorbent from walnut shells with different carbon content. The hydrophobicity and oleophilic of their surface are common to all these materials. The dynamic conditions of the adsorption capacity processes under the sorbents were studied. Sorption efficiency and the specific capacity of sorbents were determined. It has been shown that the technological cycle of the studied sorbents can be repeated by repeated purification. When activated charcoal is used to purify water from petroleum products, the process of leaching with colloidal and finely dispersed mixtures – it was found that deaeration is necessary. The individual composition of the ether fraction OV-1 has a fixed liquid phase, Connected to Finuigan 4023 Automated GC/MS System mass spectrometer, It was determined by chromato-mass spectrometry in a capillary column 40 m long and 0.25 mm in internal diameter. The results of the Fure-IR spectroscopy study of samples based on the apricot peel, walnut peel, and walnut peel showed that winning symmetrical bands (2920 and 2851 cm−1) were observed in them, these bands belong to the C-H-valence oscillation belonging to the methyl and methylene groups. In the spectrum taken from a sample of apricot peel, absorption bands belonging to cellulose (1377 cm−1 and 1069 cm−1 ) were observed.
 Thermogravimetric studies were performed on an STA 449C Jupiter synchronous thermal analysis instrument in the inert environment at a heating rate of 10∘ C/min in the temperature range of 25–1000∘C. Analysis of the porous structure parameters of carbon sorbents were carried out using the high-speed analyzer of gas sorption NOVA-1200e by the method of imaging nitrogen adsorption isotherms at a temperature of 77K.

Chemistry-mediated Ostwald ripening in carbon-rich C/O systems at extreme conditions

There is significant interest in establishing a capability for tailored synthesis of next-generation carbon-based nanomaterials due to their broad range of applications and high degree of tunability. High pressure (e.g., shockwave-driven) synthesis holds promise as an effective discovery method, but experimental challenges preclude elucidating the processes governing nanocarbon production from carbon-rich precursors that could otherwise guide efforts through the prohibitively expansive design space. Here we report findings from large scale atomistically-resolved simulations of carbon condensation from C/O mixtures subjected to extreme pressures and temperatures, made possible by machine-learned reactive interatomic potentials. We find that liquid nanocarbon formation follows classical growth kinetics driven by Ostwald ripening (i.e., growth of large clusters at the expense of shrinking small ones) and obeys dynamical scaling in a process mediated by carbon chemistry in the surrounding reactive fluid. The results provide direct insight into carbon condensation in a representative system and pave the way for its exploration in higher complexity organic materials. They also suggest that simulations using machine-learned interatomic potentials could eventually be employed as in-silico design tools for new nanomaterials.

Controlled Growth of Unusual Nanocarbon Allotropes by Molten Electrolysis of CO2

This study describes a world of new carbon “fullerene” allotropes that may be synthesized by molten carbonate electrolysis using greenhouse CO2 as the reactant. Beyond the world of conventional diamond, graphite and buckyballs, a vast array of unique nanocarbon structures exist. Until recently, CO2 was thought to be unreactive. Here, we show that CO2 can be transformed into distinct nano-bamboo, nano-pearl, nano-dragon, solid and hollow nano-onion, nano-tree, nano-rod, nano-belt and nano-flower morphologies of carbon. The capability to produce these allotropes at high purity by a straightforward electrolysis, analogous to aluminum production splitting of aluminum oxide, but instead nanocarbon production by splitting CO2, opens an array of inexpensive unique materials with exciting new high strength, electrical and thermal conductivity, flexibility, charge storage, lubricant and robustness properties. Commercial production technology of nanocarbons had been chemical vapor deposition, which is ten-fold more expensive, generally requires metallo-organics reactants and has a highly carbon-positive rather than carbon-negative footprint. Different nanocarbon structures were prepared electrochemically by variation of anode and cathode composition and architecture, electrolyte composition, pre-electrolysis processing and current ramping and current density. Individual allotrope structures and initial growth mechanisms are explored by SEM, TEM, HAADF EDX, XRD and Raman spectroscopy.

Mg and Cu incorporated CoFe2O4 catalyst: characterization and methane cracking performance for hydrogen and nano-carbon production

The Cobalt ferrite (CoFe2O4) and cobalt ferrite incorporated with Cu (Cu–CoFe2O4) and Mg (Mg–CoFe2O4) have been synthesized by wet chemical route. In fixed-bed reactor, the CoFe2O4, Cu–CoFe2O4 and Mg–CoFe2O4 were used as catalysts for direct cracking of methane at temperature of 800 °C and 20 mL/min of feed gas flow rate for hydrogen and nano-carbon production. Different characterizations techniques namely XRD, FESEM, XPS, Raman spectroscopy, TGA, BET for fresh and spent catalysts have been executed. The X-ray powder diffraction and Raman spectra confirmed that the fresh catalysts possess a cubic spinel crystal structure. The FESEM images for spent catalysts displayed that filamentous carbons were not formed over catalysts surfaces except a few amount was observed over the spent CoFe2O4 catalyst. XPS results confirmed the purity of the synthesized catalysts and qualitatively evaluate the cation distribution between the tetrahedral and octahedral sites from Co 2p3/2 and Fe 2p3/2 spectra. BET surface area revealed no significant effects in surface area and pore size of CoFe2O4 catalyst by incorporation of Mg and Cu metals. Activity studies showed that incorporation Mg metal on CoFe2O4 improved methane conversion up to 40.03% and hydrogen formation rate of 79.90 mol H2 g−1 min−1 as compared to 31.61% and 66 mol H2 g−1 min−1 for CoFe2O4 catalyst. Whilst, Cu metal incorporation in CoFe2O4 catalyst led to decline the catalyst performance. Structure activity relationship was described in details.

Single catalyst particle growth modeling in thermocatalytic decomposition of methane

ThermoCatalytic Decomposition of methane (TCD) is studied as a method to convert natural gas into hydrogen and functional carbon. In these processes the carbon typically formed on top of a catalyst phase leading to particle growth. Therefore, the development of a particle growth model is necessary to understand the limitations of thermocatalytic decomposition of methane and to assess optimal parameters and process conditions. In this paper, a particle growth model is presented to describe the growth of functional carbon on the catalyst particle. This coupled model requires kinetic equations and information on deactivation rates which have been studied from literature. The morphology of the particle changes due to carbon formation, which leads to eventual deactivation. Therefore, these kinetic expressions are coupled to a particle growth model based on the analogy with the growth of particles in polyolefin production. To combine the effects of particle growth, kinetics, and internal heat and mass transfer, the Multi-Grain Model (MGM) was used. Results confirm that with the currently available catalysts the carbon yield is not affected by heat and mass transfer limitations, however, with the availability of more active catalysts these limitations will become important. Temperature, however, has a significant role in that it regulates the kinetic rate and thus growth rate, which in turn influences the catalyst deactivation. The optimum temperature for the production of nano-carbon, within a reasonable process time, therefore sensitively depends on the choice of catalyst. • Development of a particle growth model for Thermocatalytic decomposition of methane. • Combined mass/heat transfer, kinetics and particle growth using a multi-grain model. • Assessment of transfer limitations and temperature using available kinetic models.

Preparation and optimization of activated nano-carbon production using physical activation by water steam from agricultural wastes.

Production of activated nano-carbon from agricultural wastes was studied in this work. To obtain the optimum production conditions by a physical activation method, influence of temperature (850, 900, 950 and 1000 °C), activation residence time (30, 60 and 90 min), and mill rotation (200, 300 and 400 rpm) were investigated using three different raw materials including walnut, almond and pistachio shells. To prepare activated nano-carbon, all the samples were heated up to the final activation temperature under a continuous steam flow of 130 cm3 min−1, and at a heating rate of 3 °C min−1, and were held at the different activation temperatures for 30, 60 and 90 minutes. BET surface area of the obtained activated carbons was measured from nitrogen adsorption data in the relative pressure range between 0 to 1. Activated nano-carbon standard indexes were evaluated according to the ASTM standard and the samples were compared. First, the cellulose raw material was heated in the carbonization furnace at 600 °C and then activated in the advanced activation furnace at a temperature between 850 to 1000 °C for 30, 60 and 90 minutes with water vapor. Ash percentage, iodine content, moisture content, specific area, elemental analysis, and FESEM were used for product characterization. The results of the analysis showed that by using the water vapor physical activation method and optimizing the parameters of this process including time and rotation of the mill up to 10 min and 400 rpm, resulted in a significant increase in specific surface area, cavity volume and the iodine number of the final product.

Nitrogen Doped Nanoporous Carbon Derived from Zizania Latifolia for Adsorptive Removal of Bisphenol A.

Nitrogen doped nanoporous activated carbon (N-NPAC) was prepared via the facile and effective KOH activation method using Zizania latifolia (ZL), a common Chinese aquatic vegetable, as the raw material. The biomass derived N-NPAC exhibited high content of nitrogen (18.4 at%), large surface area (1493.4 m²/g) and abundant nanopores. The unique physical-chemical structure endows the N-NPAC with great application potential in adsorbents. The performance of the N-NPAC for the adsorptive removal of bisphenol A (BPA) was studied. The results showed the adsorption processes were barely affected by solution pH. The adsorption kinetics are well-fitted by the pseudo-second-order kinetic model and the adsorption isotherms followed the Langmuir isotherm model. The maximum adsorption capacity calculated by the Langmuir isotherm model is 555.5 mg/g at 313 K, demonstrating the promise of the N-NPAC for the application in water cleanup. This study provides an example using the inexpensive and abundantly available biomass as the raw materials for the large scale production of nanocarbons and paves an avenue for the development of bio-derived nanomaterials.

Opto-electric property relationship in phosphorus embedded nanocarbon

Abstract Graphene, due to its zero band gap, has an excellent combination of the important features such as ballistic transport, tensile strength and chemical tuning, which are practically hindered in opto-electric applications. The precursors used in the production of nanocarbon are relatively costlier; however, that their production processes include difficulties is a harder problem. It is possible to control the size, structure and properties of the produced nanocarbon matrix by tuning sp2 domains in the matrix. In this respect, the coal, being a potential candidate for the synthesis of nanocarbon which holds promising applications, has attracted remarkable interest. The nanocarbon structure reported in this paper was synthesized from bituminous coal and then phosphorus atoms were added into the produced structure in order to obtain resultant composite structure, whose structural properties were illustrated here in detail by using the X-ray, IR and UV–Visible spectroscopy techniques. A systematical analysis of the optical and electrical properties of the produced composite has revealed that a composite structure to be produced in the ratio 1:2 of nanocarbon + phosphorus has better optical and electrical properties. We report here that the composite produced in this study from nanocarbon by adding phosphorous atoms shows unique photoluminescent property in particular due to the dominance of quantum confinement and oxygen functionalities. The observed increase in the dielectric strength, which results from interfacial polarization and its frequency independent nature, is desirable for the fields such as supercapacitor, sensor, stealth applications etc.

Preparation and characterization of nanocarbons from <i>Nicotiana tabacum stems</i>

Nanocarbon materials can improve adsoption capacity if the nano size range is optimized during production. In this study, nanocarbons were prepared from green recyclable waste N. tabacum stem using carbonization process and KOH as the activating agent, thus potentially unclocking value in the otherwise waste material. The formation of nanocarbons was investigated at different KOH concentration, activation temperature and carbonization time. Fourier Transform Infrared (FT-IR) spectroscopy, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Brunauer–Emmett–Teller (BET) techniques were used to characterise the nanocarbon material. The results showed that nanocarbons with high specific surface areas in excess of 950 m 2 /g and nanostructured morphologies characterized by pore width averages ranging from 3.33–8.87 nm, pore diameter 10.59–45.30 nm and particle size 25.34–54.88 nm could be formed. Optimum nanocarbon production was achieved when the precursor was activated using 10% KOH and carbonized at a temperature of 400 ℃ for 4 h. Characteristic FT-IR absorption bands were observed in all carbonized samples. SEM images revealed a dense irregular material with cavities and protuberances. XRD patterns showed that crystallinity of the nanocarbons decreased with increase in carbonization time. The properties reported for the nanocarbons are ideal for adsoption of analytes from complex matrices, hence presenting N. tabacum as a promising low-cost and green alternative precursor for nanocarbon production targeting analytical fields such as solid-phase extraction and solid phase microextraction. The produced nanocarbons appear to be carbon nanoparticles comprising nearly spherical particles.

Finding an Optimum Period of Oxidative Heat Treatment on SS 316 Catalyst for Nanocarbon Production from LDPE Plastic Waste

Plastic waste accumulation has become a major health and environmental problems in many parts of the world. Many efforts have been taken to reduce the accumulation, one of which is to convert it into a more useful products, such as CNT. CNT have been used for several products to enhance its properties. In this work, Low Density Polyethylene (LDPE) plastic waste was used as a feed to produce CNT with the help of wired mesh stainless steel type 316 serving as the catalyst. The stainless steel was pretreated by applying heat under oxidative environment at 800 o C. The time of the pretreatment was varied from 0, 1, 5, 10, and 20 minutes to determine the relationship between the period of the pretreatment and the produced CNT quality. The collected nanocarbons were characterized by using XRD, SEM-EDX, TEM, and TGA. It was discovered that CNT was formed from the pretreated catalyst. The best result was obtained from the 10 minutes pretreatment shown by formation of buckling and continuous growth CNT having an evenly spread carbon with a mean CNT diameter of 7.70 nm, carbon percentage up to 93.3%, and oxidation temperature up to 530 o C.

Shape-controlled synthesis of nanocarbons through direct conversion of carbon dioxide

Morphology control of carbon-based nanomaterials (nanocarbons) is critical to practical applications because their physical and chemical properties are highly shape-dependent. The discovery of novel shaped nanocarbons stimulates new development in carbon science and technology. Based on direct reaction of CO2 with Mg metal, we achieved controlled synthesis of several different types of nanocarbons including mesoporous graphene, carbon nanotubes, and hollow carbon nanoboxes. The last one, to our knowledge, has not been previously reported to this date. The method described here allows effective control of the shape and dimensions of nanocarbons through manipulation of reaction temperature. The formation mechanism of nanocarbons is proposed. As a proof of concept, the synthesized nanocarbons are used for electrodes in symmetrical supercapacitors, which exhibit high capacitance and good cycling stability. The reported protocols are instructive to production of nanocarbons with controlled shape and dimensions which are much desirable for many practical applications.

Production, identification, and use of nanocarbon in vehicles’ frictional systems

Nanocarbon production by the decomposition of hydrocarbon gas at atmospheric pressure is considered; no catalysts are employed. The role of nanocarbon in improving the antifrictional, antiwear, and antiscratch properties of lubricants is studied.

Aggregation kinetics of detonation nanocarbon

We analyze the properties of diffusion-limited coagulation and associated energy release applicable to processes such as nanocarbon production in detonation or nanoaerosols growth. We introduce a physical model that yields the expected energy release by treating the aggregation kinetics as a quasi phase transformation with a nonlinear rate dependent on the size of the initial nuclei, thermodynamic conditions, and viscosity of the fluid matrix.

Creation of spherical carbon nanoparticles and clusters from carbon dioxide via UV dissociation at the critical point

Carbon nanomaterials have become increasingly important for many applications, including sensors, electronics, biomedical materials and functional composites. Currently their production is based on hydrocarbons or graphite and requires very high temperatures. Here we present a method for the synthesis of carbon nanomaterials from carbon dioxide. Unlike previously described methods, our synthesis method works near room temperature. Carbon dioxide is irradiated at its critical point, producing spherical carbon nanoparticles even without the use of a catalyst. We examine the influence of irradiation parameters and different metals and catalysts on the nanocarbon production. Together with analysis of the fluid phase, this allows us to draw some conclusions on the carbon dioxide dissociation mechanism.

Voltage effects on the production of nanocarbons by a unique arc-discharge set-up in solution

Well graphitised nanocarbons including onion-like fullerenes and single- and multi-walled carbon nanotubes (CNTs) were synthesised in high yield by automatic arc-discharge method in solution. This technique is considered a low-cost method since it does not require any expensive equipment. Herein, an arc discharge full automatic set-up was used for fabrication of CNTs which enables controlling of the gap between the two electrodes and the voltage as well. Carbon nanostructures under a controlled amount of voltage (from 10 to 30 V) were synthesised where Ni : Mo as a catalyst and LiCl 0.25 M as a solution were used. Subsequently, a modified acid treatment method was applied as purification stage of the products. The production rate of CNTs was as high as 7.7 mg min−1 while the voltage was set at 30 V. Scanning electron microscopy and transmission electron microscopy as well as Raman spectroscopy were employed to study the morphology of these carbon nanostructures. The results indicated that CNTs synthesised at a voltage of 30 V had the best quality and elongated straight structures. The mechanism of the voltage conditions for preparing nanocarbons as well as their characterisation are discussed.

Novel and Practical Separation Processes for Fullerenes, Carbon Nanotubes and Nanodiamonds

Nanocarbons, defined as nanometer-sized carbon clusters including fullerenes, carbon nanotubes and nano-diamonds, are one of the most fascinating materials known today. Applications for electronics and optics require controlled size and/or structure of these materials, because the physical properties are well known to closely correlate with the structures. Therefore, separation methods of nanocarbons have been investigated, in particular practical processes applicable to large-scale separation. This review describes three novel and practical methods for separating fullerenes, carbon nanotubes and nanodiamonds, which have been developed in our group. In fullerene separation, a solution of fullerene mixture including C60, C70 and C>70 was filtered through a thin layer of activated carbon to provide pure C60 and C70. Since this process is very useful, many patents were filed, and this technology was successfully transferred to a company. Circular single-walled carbon nanotubes were obtained in high purity by use of ultrasonic atomization. While this sonochemical process has been employed only for homogeneous systems such as concentration of aqueous ethanol, this is the first example to apply the sonoprocess to solid/liquid biphasic system. Separation of nanodiamond by centrifugation was effective to obtain single-digit nanometer size diamonds as small as 4 nm from nanodiamond powder with median size of 30 nm. This process was successfully applied to large-scale separation. Filtration, sonication and centrifugation are very fundamental experimental techniques which can be used for the separation of these three types of nanocarbons. Therefore, these processes are expected to be applied to the industrial scale production of nano-carbons, which should reduce cost and increase availability.

Natural Lavas as Catalysts for Efficient Production of Carbon Nanotubes and Nanofibers

Mount Etna provided the lava rocks used for the direct synthesis of carbon nanotubes and nanofibers by chemical vapor deposition (see image; scale bar: 15 μm). Since the iron oxide particles abundantly present serve as a natural catalyst, this could be an effective approach for the efficient production of nanocarbons.

Synthesis of Various Types of Nano Carbons Using the Template Technique

Abstract Using uniform nanochannels of an aluminum anodic oxide film as a template, uniform and unique multiwalled carbon nanotubes can be synthesized with a selectivity of 100%. This technique allows one to precisely control the diameters and the length of nanotubes. Moreover, it is possible to chemically modify only the inner surface of carbon nanotubes and to prepare carbon nanotubes with a double coaxial structure of heteroatom-doped multiwalls. The test tube like carbon prepared by this technique was found to be dispersible in water without any post treatment. In addition to this one-dimensional approach, unique microporous carbon can be prepared by the template technique using zeolite Y. The resulting microporous carbons are characterized by their regular ordering, originating from the regularity of the parent zeolite. When the synthesis conditions were optimized, the specific surface area and the micropore volume of the zeolite-templated carbon reach more than 4000 m2 g−1 and 1.8 cm3 g−1, respectively. This review introduces such a template-mediated approach and highlights how useful and versatile the template technique is for the production of nano carbons.