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Effect of CoMo metal loading on H2 and CNTs production from biogas by integrative process
(2022-12-19)
Aieamsam-Aung, Pichawee
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Nantapong, Paveenuch
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Rattanaamonkulchai, Raminda
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Kludpantanapan, Thunyathon
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Srifa, Atthapon
Effect of CoMo metal loading to MgO (1, 5, 30 and 50 wt%) on conversion of biogas by an integrative process was investigated at 900 °C under atmospheric pressure. The integrative process combines the direct methanation of CO<inf>2</inf> in biogas and the CH<inf>4</inf> decomposition to upgrade biogas to CH<inf>4</inf> and decompose to hydrogen and carbon nanotubes. Methane dissociative reaction is governed by the concentration of active metals on the catalyst surface, while DRM reaction is suppressed. The 30 wt%CoMo catalyst shows the optimal loading for production of high-purity H<inf>2</inf> (>90v/v%) and high yield of MWCNTs (2.33 gCNT/gCat-h) with 100%CO<inf>2</inf> conversion and 95%CH<inf>4</inf> conversion. Meanwhile, 1 wt%CoMo catalyst provided the single-walled CNTs with diameter of 2.5 nm, high surface area of 165 m2/g and high graphitization of I<inf>G</inf>/I<inf>D</inf> = 6.14.
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Simultaneous production of hydrogen and carbon nanotubes from biogas: On the design of combined process
(2022-04-15)
Rattanaamonkulchai, Raminda
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Kludpantanapan, Thunyathon
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Nantapong, Paveenuch
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Srifa, Atthapon
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Koo-Amornpattana, Wanida
We introduced a novel combined process of CO<inf>2</inf> methanation (METH) and catalytic decomposition of methane (CDM) for simultaneous production of hydrogen (H<inf>2</inf>) and carbon nanotubes (CNTs) from biogas. In this process, biogas is catalytically upgraded into CH<inf>4</inf>-rich gas in METH reactor using Ni/CeO<inf>2</inf> catalyst, and the obtained CH<inf>4</inf>-rich gas is subsequently decomposed into H<inf>2</inf> and CNTs in CDM reactor over CoMo/MgO catalyst. Among the three different process scenarios proposed, the combined process with a steam condenser equipped between METH and CDM reactors could greatly improve a CNTs productivity. The CNTs production yield increased by more than 2.5-fold, maximizing at 9.08 gCNTs/gCat with a CNTs purity of 90%. The deposited carbon product was characterized as multi-walled carbon nanotubes (MWCNTs) with a surface area of 136.0 m2/g, comparable with commercial CNTs of 199.8 m2/g. The remarkable I<inf>G</inf>/I<inf>D</inf> ratio of 2.18 confirms a superior portion of graphitic carbon in the synthesized CNTs upon the commercial CNTs with I<inf>G</inf>/I<inf>D</inf> = 0.74. Notably, the CH<inf>4</inf> conversion reached 94.5%, while the CO<inf>2</inf> conversion achieved 100%, resulting in the H<inf>2</inf> yield and H<inf>2</inf> purity higher than 90%. This combined process demonstrates a promising route for production of high quality CNTs and high purity H<inf>2</inf> with complete CO<inf>2</inf> conversion using biogas as abundant renewable energy resources. In addition, the test of raw biogas showed no deactivation of catalyst, justifying the implementation of the developed process for real biogas without purification.
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Synergistic effect of nickel nanoparticles and carbon nanotubes buckypaper for enhancement of microwave shielding properties
(2020-01-01)
Sukgorn, Nuttaya
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Yordsri, Visittapong
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Thanachayanon, Chanchana
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Horprathum, Mati
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Chudpooti, Nonchanutt
Carbon nanotubes (CNTs) are considered as the most promising materials to solve the electromagnetic interference (EMI) issue. Various forms of CNTs including CNTs/polymer composites, metal nanoparticles-decorated CNTs and freestanding CNT buckypapers (CNT BPs) have been proposed to enhance shielding effectiveness. In this study, the synergistic effect of nickel nanoparticles (NPs) and relatively short CNTs for the enhancement of microwave shielding properties was investigated. CNT BPs were prepared by vacuum filtration of well-dispersed multi-walled CNTs and subsequently nickel was decorated on the CNT BPs (Ni/CNT) by pulsed DC sputtering technique with different deposition times of 0, 5, 10 and 15 min (hereinafter referred to as CNi0, CNi05, CNi10 and CNi15, respectively). The diameter of Ni/CNT increased from 8.74±0.53 to 72.5±3.2 nm and the conductivity improved from 9.57±0.87 to 12.57±0.59 S/cm when the nickel deposition time was 15 min. Nickel NPs were the mixed phases of nickel and nickel oxide with a dominant nickel phase. The shielding effectiveness at the frequency of 9.5 GHz achieved to-34.1 dB for CNi15. The enhancement of shielding effectiveness of CNi15 is attributed to the synergistic effect of CNTs and nickel NPs on wave dissipation.
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Alcohol sensing properties of SnO2/CNT nanocomposites synthesized by microwave-assisted process
(2016-01-01)
Sawangjit, Nalita
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Techitdheera, Wichan
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Pecharapa, Wisanu
SnO<inf>2</inf>/CNT nanocomposites were synthesized via microwave-assisted process using SnCl<inf>4</inf>·;5H<inf>2</inf>O as a starting precursor and UV-treated multi-wall carbon nanotubes (MWCNTs) as scaffolds. The concentration of SnCl<inf>4</inf> was varied in the range of 0.01-0.05 M. Effect of precursor concentration on their physical properties and micro structural morphology were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). XRD results indicate that the assynthesized composites are the mixture of two separated phases including SnO<inf>2</inf> and MWCNT. SEM images indicate that the surfaces of MWCNT are thoroughly covered with SnO<inf>2</inf> nanoparticles. Comparative gas sensing result reveals that the prepared hybrid SnO<inf>2</inf>/MWCNT composites exhibit much higher sensing sensitivity and recovery property in detecting alcohol gas at room temperature than the bare SnO<inf>2</inf>.
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Performance improvement of zinc oxide photoanode-based dye-sensitized solar cells by multi-walled carbon nanotube
(2010-11-01)
Chindaduang, Anon
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Duangkaew, Pattasuda
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Pratontep, Sirapat
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Tumcharern, Gamoiwan
Unique electrical and surface-to-volume properties of carbon nanotubes have made these conductive molecules highly attractive in many applications. In this work, the influence of multi-walled carbon nanotubes into a zinc oxide active layer of dye-sensitized zinc oxide solar cell has been investigated. With this method, a significant improvement in the performance of the solar cell has been achieved. Compared to the typical zinc oxide photoelectrochemical cells, the photocurrent- voltage characteristics of the fabricated cell containing 0.05 percent by weight of carbon nanotubes in the metal oxide film displayed a higher short-circuit photocurrent, consequently caused an increase of the solar-to-electricity conversion efficiency by a factor of approximately 1.4. Further increase of the conductive carbon material resulted in a decrease of the energy conversion of the photovoltaic cell. The enhancement of the energy conversion at this optimum carbon nanotube loading may be attributed to the dye-adsorption ability and the electrochemical activity of the composite photoanodes. The fabricated photovoltaic cells with the highest efficiency exhibited the maximum dye adsorption intensity and the minimum charge transfer resistance, as measured by ultraviolet-visible spectroscopy and electrochemical impedance spectroscopy, respectively . Copyright © 2010 American Scientific Publishers.
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Alcohol sensor based on multi-wall carbon nanotube
(2009-12-01)
Sutthinet, Chalin
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Sangnual, Assuchol
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Phetchakul, Toempong
We have demonstrated multi-walled carbon nanotube (MWCNTs) based sensors, which are capable of detecting alcohol vapor. The properties of the sensor were as a function of baking times at ethanol flow rate 200 cc/min and nitrogen gas flow rate 200 cc/min. Moreover, the various of baking times were observed that the highest sensitivity was obtained at baking time of 25 minutes at 70 ° C can be explained for residual of ethanol on the surface .It was found that the optimum operating at room temperature (25 °C). It is expected that many applications of CNTs-based sensors will be explored in future as the interest of the nanotechnology research in this field increases.
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Effect of the deposition condition for carbon nanotube thin films on gas sensing performance
(2008-01-01)
Chaisitsak, S.
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Tuantranont, A.
A simple fabrication process for single-walled carbon nanotube (SWCNT)-based sensors was reported. By using chemical vapor deposition (CVD) of alcohol-ferrocene mist, SWCNT films could be directly deposited on patterned Al electrodes to fabricate a sensor. The effects of depositing position along the inner quartz reactor on the properties of SWGNT films (morphology, structure and purity) and the characteristics of sensors (response and reproducibility) were investigated. The SWCNT-film-based sensors fabricated at low substrate temperatures of 200-700 °C exhibited a reasonably good sensitivity to saturated organic vapor (ethanol, methanol and acetone) and showed a fair reproducibility even operated at a room temperature (∼28 °C). Copyright © 2008 American Scientific Publishers All rights reserved.
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Parametric study of atmospheric-pressure single-walled carbon nanotubes growth by ferrocene-ethanol mist CVD
(2007-11-01)
Chaisitsak, S.
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Nukeaw, J.
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Tuantranont, A.
Uniform web-like films consisting single-walled carbon nanotubes (SWCNTs) were deposited on a silicon substrate using the chemical vapor deposition (CVD) of ferrocene-ethanol mist at atmospheric pressure (∼ 1 atm). The tiny mist was generated using a high-frequency ultrasonic vibration. The effects of various parameters including deposition position in the reactor, temperature, ferrocene/ethanol ratio, flow rate of carrier gas (argon), and deposition time on the formation of SWCNTs was investigated using high-resolution scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The worm region outside the furnace was found to be a suitable position for the formation of SWCNT films. The furnace temperature and the flow rate of carrier gas were found to determine the diameter and crystallinity of nanotube. The ferrocene concentration in ethanol strongly influenced the amount of impurity particles in the material. Moreover, the intensity of metallic tail in D-band was found to decrease with increasing the flow rate, showing a possibility of the formation of semiconducting SWCNTs. Results of this study can be used to improve understanding of the growth of SWCNTs by floating catalyst CVD of alcohol mist. © 2007 Elsevier B.V. All rights reserved.

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