The Carbon Nanotubes Synthesized From Petroleum Residue By Arc Discharge And Its Applications

Carbon nanotube(CNT),arranged by carbon atoms alone,is widely recognized as a star in one dimensional material.Due to its extraordinary mechanical,electromagnetic,optical and chemical properties,CNT has caused widespread attention among scientific communities ever since its discovery.Here,we successfully synthesized CNT via an arc discharge methods under different atmospheres with cheap petroleum based materials(petroleum asphalt and coke)as feedstock and iron as the catalyst.These achievements not only pave a new way for the value-added utilization of petroleum asphalt and coke,but also provide constructive strategy to precisely tune the number of CNT layers.In addition,the parameters of the growth condition associated with detailed growth mechanism were also investigated.Inspired by the semi-conductor property of CNT,along with our observation that during the arc discharge process the metal catalysts tend to transform into metal nanoparticles which strongly adhered onto the surface of CNT,we applied the resulting CNT based material into the field of clean energy,namely solar cells and fuel(gasoline and diesel)hydrodesulfurization.Major results are as follows:Single-,double-and triple-walled carbon nanotubes were controllably synthesized using petroleum asphalt and coke as feedstock.Our findings indicate that during arc discharge process single-walled carbon nanotube(SWCNT)can be formed,with petroleum asphalt as feedstock under helium(He)atmosphere,while when the atmosphere is nitrogen(N2),double-walled carbon nanotube(DWCNTs)will be synthesized.Interestingly,the mixture of SWCNT and DWCNTs with a ratio of 1:1 is formed using petroleum coke as feedstock and N2 as atmosphere.Moreover,when the atmosphere is set as argon(Ar),double-and triple-walled CNTs with high purity can be synthesized using coke and petroleum asphalt as feedstock,respectively.It is worth mentioning that the yield of CNT is rather low when using petroleum asphalt as feedstock,whereas much higher yield of CNT can be achieved when employing coke as feedstock.In particular,during the preparation of coke derived DWCNTs,the maximum yield reaches 7.82%.The coke-based SWCNTs and DWCNTs were used for solar cells due to their p-type semi-conducting property.SWCNT-based solar cells exhibit better photovoltaic performance than DWCNTs based solar cells when being exposed in LED light under the same power density with their wavelength ranging from 400 to 940 nm.Notably,the output power of SWCNTs based solar cells are found to be more sensitive to the LED light with wavelength of 630 nm and 940 nm,whereas the maximum output power of DWCNT based solar cell occurs at the wavelength of 800 nm.Additionally,under the LED light with the same wavelength,the current density and open circuit voltage of the SWCNTs and DWCNTs based solar cells both first increase with the increase of input power until steady values are achieved,while the power conversion efficiencies both experience a drop with the input power increases.Interestingly,when exposed in the infrared light with a wavelength of 1310 nm,DWCNTs based solar cells achieve a better performance.Specifically,DWCNTs and SWCNTs based solar cells show comparable current densities,however,by virtue of the narrow band gap,DWCNTs absorb more infrared light,which results in almost double open circuit voltage than that of SWCNTs based solar cells.During the arc discharge process of CNTs synthesis,metal catalysts tend to transform into metal nanoparticles and be strongly adhered onto the surface of CNTs.Inspired by the aforementioned characteristic,we synthesis a novel hydrodesulfrization catalysts in which CNTs are act as support and metal(nickel and yttrium)nanoparticles are function as the active sites.It is proved that nickel and yttrium supported SWCNTs based catalysts show excellent ultra-desulfurization performance especially when the catalyst is subject to oxidation treatment.The oxidation treatment oxidized a certain proportion of the pure metal,which facilitate the self-sulfurization during the HDS process by reacting with H2 S,thus significantly enhancing the HDS activity.The activities of the catalysts are evaluated and optimized on a fixed-bed hydrodesulfurization reactor with Jinan FCC gasoline and Hohhot FCC diesel as feedstock.Our findings indicate that with a weight hourly space velocity of 2 h-1 and oxidized nickel and yttrium supported CNTs as the catalyst,the sulfur content of FCC gasoline are decreased from 259 mg/L to less than 1 mg/L for 30 h,and the sulfur content of FCC diesel are decreased from 1126 mg/L to 10 mg/L for 7 h.