Direct Flame Production of Carbon Nanotubes ( CNT ‘s ) From Liquefied Petroleum Gas ( LPG )
Liquefied crude oil gas ( LPG ) is a common family fuel used for cooking intent in India. LPG is really rich in its C content because of its specific mixing constituents of preponderantly C3 methane series ( Propane – C3H8 ) or C4 methane series ( Butane – C4H10 ) which provides a better opportunity of bring forthing strong and good quality nano merchandises like nanotubes, nanotubes nanowires, nanoparticles etc. In our research lab a lab graduated table fire reactor is designed and developed for bring forthing C nanotubes utilizing LPG as the C beginning in the presence of air as an oxidant under atmospheric conditions. The design facets and the best operational conditions of the fire reactor for bring forthing C nanotubes are discussed. The nanotubes obtained were purified and were farther characterized utilizing SEM, TEM XRD and Raman.
Carbon Nanotubes ( C ) ; TEM ( Transmission electron microscopy ) ; LPG ( methane seriess ) ; Raman ( Raman spectrometry ) ; XRD ; Flame Synthesis ;
Liquified crude oil gas ( besides called as LPG or Autogas ) is a mixture of hydrocarbon gases used as a fuel in heating contraptions and vehicles and it is progressively replacing CFCs as an aerosol propellent and a refrigerant to cut down the harm and devolution of the ozone bed. LPG is a clean, convenient energy beginning, which can be stored as a liquid under reasonably high force per unit area and used as a gas in commercial and residential warming applications. It is a common family fuel used for cooking intent in India, LPG is rich in its C content because of its specific mixing constituents of preponderantly C3 methane series ( Propane – C3H8 ) or C4 methane series ( Butane – C4H10 ) which provides a better opportunity of bring forthing strong and good quality nano merchandises like nanotubes, nanotubes nanowires, nanoparticles etc.
Carbon nanotubes ( CNTs ) are among the astonishing objects that scientific discipline sometimes creates by accident, without intending to, but that will probably revolutionise the technological landscape of the century in front. Our society stands to be significantly influenced and shaped by C nanotube applications in every facet, Carbon nanotubes have been synthesized for a long clip as merchandises from the action of a accelerator over the gaseous species arising from the thermic decomposition of hydrocarbons [ 1 ] . Since their find by Sumio Ijima [ 2 ] several ways of fixing them have been explored. The CNTs have been synthesized by assorted methods e.g. electric discharge discharge, laser vaporization and chemical vapour deposition ( CVD ) [ 3-5 ] .
Though research workers have been successful to synthesise multi-wall nano tubes they can bring forth merely in mg to gram measures in a few hours. However as many possible applications [ 6-7 ] of CNTs require kg to ton measures.
Apisit Songsasen et Al [ 8 ] have synthesized CNTs by agencies of catalytic decomposition of LPG on a Zeolite-supporting Nickel accelerator. Qian et Al [ 9 ] have reported the formation of CNTs by the decomposition of liquefied crude oil gas ( LPG ) incorporating S in the presence of Fe/Mo/Al2O3 accelerator, Since this contains S of a few to several hundred ppm, which can take to poisoning the accelerator to a great extent, few studies presently exist on utilizing LPG or natural gas straight for production of C nanomaterials, merely Prokudina et al [ 10 ] has reported CNT synthesis from LPG by CVD method, but boulder clay day of the month no information and literature is reported on direct fire synthesis of CNTs by LPG. The chief challenge in this field is to develop methods to bring forth nanotubes on a big graduated table and at low cost. As Flame synthesis of nano Cs being a uninterrupted flow method, in which fluxing gaseous feedstock mixture could bring forth CNTs in big measures it has several advantages like easy graduated table up, atom size control, double function of provender gas which serves both as C beginning and fuel, and unmoved coevals of accelerator. Hence it is one of the preferable methods for bulk production of non lone CNTs but besides other nano atoms and nano metal oxides. This method is really utile and is of widespread importance.
Many groups have investigated gas-phase continuous-flow production of C nanomaterials utilizing other hydrocarbons. These surveies typically involve go throughing a mixture of C beginning gas and organo metallic accelerator precursor molecules through a het furnace. In this paper we report the direct fire synthesis of C nanotubes utilizing LPG and air as our gaseous feedstock in a diffusion type burner without any external usage of a accelerator and synthesis at optimal procedure parametric quantities.
The fire reactor ( Fig.1 ) has been indigenously designed to bring forth C nanotubes at our university. The elaborate apparatus and procedure instrument and diagram ( PID ) of the reactor ( Fig. 2 ) has been discussed in item in our old work [ 11 ] . In general our reactor operates under atmospheric force per unit area. The mensural measure of the LPG and the oxidant reaches the ignition chamber where the partial burning procedure occurs where the CNT ‘s are produced. During the procedure we have observed the dark orange fire colour which is absolutely in a spindle signifier. Along the full length of the fire, its temperature was recorded utilizing a K-type thermocouple where this temperature can supply some informations sing the growing of nanotubes. The carbon black therefore produced is captured on a glass fibre filter ( Axiva GF/A ) with the assistance of a vacuity pump and the gathered carbon black is scrapped carefully and weighed and subsequently heat treated and oxidized at 550 OC in the presence of air for 60 proceedingss to take any hints of formless C drosss and so the sample is reweighed in order to gauge the loss of formless C as an dross so the samples are subsequently characterized by SEM, TEM, XRD and Raman for their quality. The entire sum of thermally oxidized and purified sample from the experiment ( for 30 infinitesimal tally ) weighed merely 0.8g.
3. Consequences and Discussion
3.1 Scaning Electron Microscope Analysis
The samples were analyzed utilizing Phillips XL 30 series Scanning Electron Microscope ( SEM ) from National Center for Compositional Characterization of Materials ( NCCCM ) , Hyderabad. From the Figs ( 3a – 3d ) we can see a heavy growing of C nanotubes at assorted flow rates with regard to the oxidizer to fuel ( O/F ) ratios between 0.7 – 1.0 slpm/slpm ( standard liter per minute ) . The mean diameter scope of the CNTs from the SEM image was found to be about 200 nm -1000 nanometer and lengths greater than 40 ?m.
3.2 Transmission Electron Microscope Analysis
The TEM ( Technai -12, FEI ) images ( Fig 4a ) shows the presence of thickly packed multiwalled CNT with an mean diameter of 150 – 250 nanometer which is still surrounded by hints of carbonous nanoparticle aggregates perchance caused due to the scattering of the sample in the dissolver. This can be assumed that the agglomerative C nanoparticles were really protected by the CNTs during the thermic intervention, as the CNTs might hold formed a net like bed covering the nanoparticles and protecting it from the heat and oxidization. Fig 4b shows a thick multi walled CNT around 250 nanometers in its diameter with tonss of hints of agglomerative C nanoparticles which can be accounted for the presence of C60 atoms which is besides in understanding with the XRD analysis in Fig 5. The broken caps of the CNTs besides reveal the freak out and a faulty growing of the character beds as seen in the Raman analysis in Fig 6.
3.2 X-ray Diffraction Analysis
The XRD ( PW1830 Phillips ) analysis was carried out utilizing CuKa1 type of radiation with a wavelength ( cubic decimeter ) of 1.54060 A. XRD ( Fig. 5 ) of nanotubess produced utilizing LPG-air at an O/F ratio of 0.7 slpm/slpm shows a heterogenous crystallinity in the sample. The natural scan detected three strong extremums. The first extremum at 2? angle of 25.77O was found with ( 110 ) orientation of atoms along its plane with peak matching to graphite with an orthorhombic type of system and an end-centered lattice. The 2nd extremum at 2? angle of 43.159O was found with ( 245 ) orientation of atoms along its plane with peak matching to C60 molecule with a three-dimensional type of system and a crude lattice. The 3rd extremum at 2? angle of 83.475O was found with ( 112 ) orientation of atoms along its plane with peak matching to graphite with a hexangular type of system and a crude type lattice severally.
3.2 Raman Analysis
Raman analysis ( Horiba Jobin Yvon T64000, Raman Spectrophotometer ) was carried out merely on the best sample ( Fig.6 ) which clearly shows the D set & A ; G band severally. The D set ( the upset set is well-known in broken graphitic stuffs and located between 1330-1360 cm-1 when it is excited with a seeable optical maser ) it is expected to be observed in Multi Walled Nanotubes ( MWNT ) . However when the D set is observed in SWNT ‘s [ 12 ] , it is assumed to incorporate defects in the tubing. The G set or ( TM- Tangential Mode ) [ 12 ] , corresponds to the stretching manner of the -C-C- bond in the graphite plane [ 12 ] . This manner is located near 1580 cm-1. From the figure we can state that the nanotubes are in the somewhat disordered graphite stage based on the D set wavelength nowadays at 1349 cm-1. This D set besides confirms the presence of formless province of C in the majority sample. Based on the G set from the figures, there appears two extremums at 1560 and 1600 cm-1 severally which proves the presence of multi beds of broken graphene sheets. On analysing the degree of graphitization utilizing the D and G set strengths ratio, we find that the sample is usually good graphitized with little grade of crystallinity and its ID/IG ratio was found to be about 0.939.
Carbon nanotube ( CNT ) is a various group of applied chemicals with high grade of applications on larger graduated table in assorted subjects. The synthesis, purification and the cost still remains an un-doubted argument around the universe hence an economical attack is to be developed in order to bring forth big sums of good quality CNTs from an economical and a resourceful fuel. LPG as a general trade good plays a major function since its handiness in India is high and it is a really economical beginning of fuel as good. Here, we were able to successfully synthesise semicrystalline, CNTs from LPG with an mean diameter of 100 – 500 nanometer utilizing the direct fire synthesis attack.
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