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1.
A series of experiments were conducted to produce carbon molecular sieves (CMS) through carbon deposition from a locally available
palm shell of Tenera type for separating gaseous mixtures. The process involves three stages; carbonization, physical activation with steam, and
carbon deposition by using benzene cracking technique. Carbonization of the dried palm shells was occurred at 900°C for duration
of 1 h followed by steam activation at 830°C for 30–420 min to obtain activated carbons with different degree of burn-offs.
The highest micropore volume of activated carbon obtained at 53.2% burn-off was used as a precursor for CMS production. Subsequent
carbon deposition of the activated sample at temperature range from 600 to 900°C for 30 min has resulted in a series of CMSs
with different selectivities of CO2/CH4 and O2/N2. The kinetic adsorption isotherm of CO2, CH4, O2 and N2 at room temperature also presented in this work. 相似文献
2.
Growth of carbon nanofibers on activated carbon fiber fabrics 总被引:2,自引:0,他引:2
Activated carbon fiber fabrics, an excellent adsorbent, were used as catalyst supports to grow carbon nanofibers. Because of the microporous structure of the activated carbon fibers, the catalysts could be distributed uniformly on the carbon surface. Based on this concept, the carbon nanofibers can be grown directly on the activated carbon fiber fabrics. We demonstrate that carbon nanofibers with a diameter between 20 and 50 nm for most of the fibers can be synthesized uniformly and densely on activated carbon fiber fabrics, impregnated by nickel nitrate catalyst precursor, using catalytic chemical vapor deposition. Although the carbon nanofibers are not straight with a crooked morphology, they form a three-dimensional network structure. Structure characterizations by TEM and XRD indicate that the carbon nanofibers have a turbostratic graphite structure and the graphite layers are stacked with a herringbone structure. 相似文献
3.
Arash Arami-Niya Wan Mohd Ashri Wan Daud Farouq S. Mjalli Faisal Abnisa Mohammad Saleh Shafeeyan 《Chemical Engineering Research and Design》2012
In this study, the optimization of the palm shell based activated carbon production using combination of chemical and physical activation for methane adsorption is investigated. response surface methodology (RSM) in combination with central composite design (CCD) was used to optimize the operating parameters of the production process. Physical activation temperature, chemical impregnation ratio and physical activation time were chosen as the main process variables and the amount of methane adsorption was selected as the investigated response. Phosphoric acid and carbon dioxide were used as chemical and physical agents, respectively. The optimum reaction conditions were found to be a physical activation temperature of 855 °C, H3PO4 impregnation ratio of 9.42 g of phosphorous per gram palm shell and physical activation time of 135 min. The results exhibited significant increase in methane adsorption after physio-chemical activation. 相似文献
4.
In this study a heat-treatment process using an activated carbon and coal-tar pitch was developed to prepare carbon molecular sieves (CMSs) for CH4/CO2 separation. This process results in a partial blockage of the pores of the activated carbon precursor, so that a reduction in the pore size takes place. Equilibrium CO2 adsorption measurements at different temperatures, and CO2 and CH4 kinetic measurements at different temperatures and feed pressures were carried out using the TEOM technique for a carbon molecular sieve (CMS) prepared by this process (sample CB3) and a commercial CMS (Takeda 3A, sampleT3A). The overall diffusion for CO2 in sample CB3 was faster than that in T3A and a slightly higher CO2 adsorption capacity of CB3 was obtained. The transient uptake profiles in both samples at different temperatures and different CO2 partial pressures were described in some cases by a micropore diffusion model, and in other cases by a dual resistance model. Both equilibrium and kinetic results demonstrate a better CO2/CH4 separation performance for the CMS prepared in the present study (CB3) than for the commercial CMS (Takeda 3A), due to the existence of slightly wider pore-mouth openings in sample CB3. This study demonstrates that the process used in this work is an interesting and reproducible approach to prepare CMS for CO2/CH4 separation. 相似文献
5.
Catalytic characteristics of activated carbon manufactured from palm shell (ACPS) for methane decomposition was studied using a thermobalance by measuring thee mass gain with time. A reaction order of 0.5 is obtained for methane decomposition over the activated carbon and the activation energy is 210 KJ mol− 1. The activity of the activated carbon had decreased in almost a linear relationship with the amount of carbon deposited at 800 °C, which indicates that the carbon deposition occurred uniformly on to the carbon surface, while diffusion effect appeared to occur significantly at the last stage of the process at reaction temperatures up to 950 °C. The study of mass gain using different particle sizes indicates the existence of mass transfer effect and the pore mouth blocking which seem to take place particularly in large particles. Comparison between ACPS and commercial based activated carbon (AC) shows almost similar values with regard to change of mass gain with time, maximum amount of carbon deposited before deactivation and the deactivation time. 相似文献
6.
为解决煤层抽放气中CH4/N2的分离问题,以椰壳炭化料为原料,采用炭化、活化和炭沉积相结合的方法,以苯为沉积剂,改变工艺条件,制备了不同性能的炭分子筛,研究了炭分子筛前驱体的种类、苯流量对炭分子筛分离效果的影响,结果表明,在炭化温度450℃,炭化时间40 min,活化温度850℃,活化时间120 min时制备的炭分子筛前驱体,进一步制成炭分子筛对CH4/N2的分离效果最好;在750℃,沉积时间30 min,苯流量0.45 m L/min时制备的炭分子筛对CH4/N2的分离效果最好。 相似文献
7.
Mekala BikshapathiAshish Sharma Ashutosh Sharma Nishith Verma 《Chemical Engineering Research and Design》2011,89(9):1737-1746
In this study, a hierarchal web of carbon micro and nanofibers was used as a precursor for the synthesis of a carbon molecular sieve (CMS). CMSs were prepared by thermal treatment of carbon fibers using a microwave heating device. The heating power and treatment time were optimized for the maximum performance of the prepared CMS for the separation of CO2 at low concentrations from the gaseous mixture of CO2 and air under dynamic (flow) conditions. Based on the experimental data, microwave power input of 240 W and treatment time of 15 min were found to be suitable for the maximum uptake of CO2 by CMS. Adsorption breakthrough curves were obtained at different gas flow rates and CO2 concentrations. CMSs prepared from the hierarchal web of carbon micro and nanofibers were found to be superior to those prepared from ACF. The CO2 uptake was determined to be approximately 0.88 mg/g and 10 mg/g at concentrations of 500 ppm and 5000 ppm, respectively, in air. 相似文献
8.
TiO2 photocatalyst deposition by MOCVD on activated carbon 总被引:1,自引:0,他引:1
Xingwang Zhang 《Carbon》2006,44(2):325-333
Activated carbon modified by HNO3 was used as the support during the production of TiO2 by metal organic chemical vapor deposition (MOCVD). The HNO3 modification increased mesopores surface area of activated carbon indicating the size of pores increased. The concentration of surface oxygen bearing groups on the HNO3 modified activated carbon was much higher than that of the original activated carbon. It was found that a modification of activated carbon by 6 mol/L HNO3 increased the deposition rate of TiO2 by 4.5 times. The modification of activated carbon by HNO3 significantly raised the photocatalytic activity of TiO2 resulting from the formation of smaller-sized TiO2 particles well dispersed confirmed by the results of XRD patterns and N2 adsorption-desorption isotherms. 相似文献
9.
炭纤维基复合吸附材料的制备及其气体分离性能研究 总被引:4,自引:0,他引:4
活性炭纤维基复合炭分子筛材料作为一种新型的吸附材料,具有丰富而发达的微孔结构、大的比表面积和优异的导电性能,这些性质使其具有独特的气体分离性能。本文以沥青基活性炭纤维和酚醛树脂为原料制备复合炭分子筛材料,用扫描电镜和氮吸附等温线法研究其外观型态和孔隙结构,在变电吸附工艺条件下以CO2为探针考察了此类复合吸附材料的分离性能。 相似文献
10.
Adsorption of methane on corn cobs based activated carbon 总被引:1,自引:0,他引:1
Activated carbon was prepared with corn cobs and potassium hydroxide under optimized variables. Due to their botanical origin, corn cobs can be an excellent starting material to produce nanoporous carbon for natural gas storage. Samples with different BET surface areas were chosen to perform methane adsorption experiments. Methane adsorptions on corn cob based activated carbon were studied at four different pressures (500, 1000, 1500 and 2000 psi) and two different temperatures (298 K and 323 K) in a volumetric adsorption apparatus. The volume based methane adsorption results specified an ‘increase in the methane adsorption capacities of activated carbon with increasing surface area and showed that adsorption capacity of methane depends on pressure and temperature. The highest methane storage capacity was found to be 160 (v/v) at 298 K and 1500 psi. The applications include use in the transportation of natural gas, natural gas based vehicles, and adsorption of gas from landfills. 相似文献
11.
为评价分析碳分子筛(Carbon Molecular Sieves,CMS)产品性能,以酚醛树脂废料为主要原料,通过添加助剂,采用炭化/气相沉积一体化工艺,制备了专用于煤层气提浓的BM碳分子筛(记为BMCMS)。采用CO_2吸附法、加压热重法及四塔变压吸附法对BMCMS及商业碳分子筛(记为JCCMS)的孔隙结构、CH_4和N_2的吸附容量、速度以及对煤层气的实际分离性能等进行研究。结果表明,BMCMS碳分子筛的孔隙以0.85 nm以下微孔为主,主要分布在0.4~0.65 nm,其比例占整个孔隙的66%以上,高于JCCMS的65%;碳分子筛的孔隙直径为N_2分子的1.1~1.8倍时,该类孔隙适宜吸附N_2,而对CH_4的吸附具有阻碍作用;当用于PSA浓缩抽采煤层气时,可将煤层气中CH_4浓度提高25.6%,实际运行指标优于JCCMS。 相似文献
12.
Xingwang Zhang 《Carbon》2005,43(8):1700-1708
Anatase TiO2 coatings on highly porous activated carbon were prepared by a novel method—atmospheric pressure metal organic chemical vapor deposition (AP-MOCVD). At a source temperature of 423 K, the TiO2 particles were mostly coated on the external surface of activated carbon. These particles were well dispersed with their sizes ranging from 10 to 50 nm. The optimum loading of TiO2 was found to be 12 wt%. The TiO2 photocatalysts so prepared behave similarly to that of the pure commercial TiO2 powder. The activated carbon supported TiO2 catalyst could be easily separated from the treated water with its catalytic performance maintained even after 10 cycles, indicating that the TiO2 coating was stable. It was observed that TiO2 supported on activated carbon had a high capacity to mineralize pollutants. Consequently, activated carbon supported TiO2 by AP-MOCVD is a promising photocatalyst for the photodegradation of pollutants in water. 相似文献
13.
Roozbeh Hoseinzadeh Hesas Arash Arami-Niya Wan Mohd Ashri Wan Daud J.N. Sahu 《Chemical Engineering Research and Design》2013
In this study, waste palm shell was used to produce activated carbon (AC) using microwave radiation and zinc chloride as a chemical agent. The operating parameters of the preparation process were optimised by a combination of response surface methodology (RSM) and central composite design (CCD). The influence of the four major parameters, namely, microwave power, activation time, chemical impregnation ratio and particle size, on methylene blue (MB) adsorption capacity and AC yield were investigated. Based on the analysis of variance, microwave power and microwave radiation time were identified as the most influential factors for AC yield and MB adsorption capacity, respectively. The optimum preparation conditions are a microwave power of 1200 W, an activation time of 15 min, a ZnCl2 impregnation ratio of 1.65 (g Zn/g precursor) and a particle size of 2 mm. The prepared AC under the optimised condition had a BET surface area (SBET) of 1253.5 m2/g with a total pore volume (Vtot) of 0.83 cm3/g, which 56% of it was contributed to the micropore volume (Vmic). 相似文献
14.
Molecular sieve properties of activated carbon fibers modified by cracking treatment with methane are studied herein. The effect of methane treatment on the porous texture of the samples has been studied while varying temperature and time. These materials have been evaluated for their selectivity during CO2 and CH4 separation; their uptakes have been compared with non-treated activated carbon fibers (studied previously), which were considered suitable to be used as molecular sieves. Kinetics of CO2 and CH4 uptake have also been investigated in this research. The treatment produced materials exhibiting fast kinetics and high selectivity during CO2 and CH4 separation; at the same time however, the CO2 uptake capacity was diminished. 相似文献
15.
Improved activated carbon by thermal treatment in methane and steam: Physicochemical influences on MIB sorption capacity 总被引:2,自引:0,他引:2
J.R. Rangel-Mendez 《Carbon》2005,43(3):467-479
Thermal treatment by steam or by methane plus steam altered the physicochemical properties of a commercial lignite-based activated carbon; and improved the carbon’s sorption capacity for the odorant 2-methylisoborneol (MIB). Rapid small scale column tests (RSSCTs) revealed that favorable thermal treatment allowed an activated carbon to remove this odorant for up to six times longer before initial MIB breakthrough than did its commercial lignite counterpart. For these RSSCTs (135 ppt), clarified water from a water treatment plant (2.07 mg/L TOC) was spiked with 14C-MIB; and liquid scintillation protocols facilitated 14C-MIB detection at 1-3 ppt. The more favorable thermal treatment at 1000 °C increased pore volumes with 5-400 Å widths by twofold; and the bed volume to initial MIB breakthrough correlated fairly well (R2 = 0.9) with pore volume in the range of 5-60 or 5-400 Å. Thermal tailoring altered the carbon’s apparent point of zero charge: from pH 6.5 for the commercial lignite carbon, to pH 9.2 for tailored carbon. When methane and steam were used together, the C, H, N and O contents were virtually the same as for the commercial lignite. In contrast, when steam was employed alone, the percent of oxygen increased, and the percent of H, C and N therefore decreased slightly. 相似文献
16.
Arash Arami-Niya Wan Mohd Ashri Wan Daud Farouq S. Mjalli 《Chemical Engineering Research and Design》2011,89(6):657-664
The objective of this study is to relate textural and surface characteristics of microporous activated carbon to their methane adsorption capacity. Oil palm shell was used as a raw material for the preparation of pore size controlled activated carbon adsorbents. The chemical treatment was followed by further physical activation with CO2. Samples were treated with CO2 flow at 850 °C by varying activation time to achieve different burn-off activated carbon. H3PO4 chemically activated samples under CO2 blanket showed higher activation rates, surface area and micropore volume compared to other activation methods, though this sample did not present high methane adsorption. Moreover, it was shown that using small proportion of ZnCl2 and H3PO4 creates an initial narrow microporosity. Further physical activation grantees better development of pore structure. In terms of pore size distribution the combined preparation method resulted in a better and more homogenous pore size distribution than the conventional physical activation method. Controlling the pore size of activated carbon by this combined activation technique can be utilized for tuning the pore size distribution. It was concluded that the high surface area and micropore volume of activated carbons do not unequivocally determine methane capacities. 相似文献
17.
Abdessalem Omri Mourad Benzina Najwa Ammar 《Journal of Industrial and Engineering Chemistry》2013,19(6):2092-2099
Almond shell was used to prepare activated carbon using physical activation method, consisted of carbon dioxide (CO2) gasification. The effects of the preparation variables which were activation temperature, activation time and carbon dioxide flow rate on the adsorption capacity of iodine and methylene blue solution were investigated. The optimal activated carbon was obtained by these conditions as follows: 800 °C activation temperature, 100 cm3/min carbon dioxide flow rate and 120 min activation time. The characterization of carbon materials is performed by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), 13C (CP/MAS and MAS) solid-state NMR, nitrogen adsorption (BET) and Boehm's titration method. For an industrial application, the optimal activated carbon was ammoxidated to improve its adsorption capacity toward total organic carbon from Tunisian industrial phosphoric acid. The influence of experimental parameters such as specific consumption, initial concentration, contact time, agitation speed and temperature on TOC removal was studied. 相似文献
18.
Thermal treatment of activated carbon fibres (ACF) has been carried out using a microwave device, instead of a conventional furnace. The results show that microwave treatment affects the porosity of the ACFs, causing a reduction in micropore volume and micropore size. More importantly, the results also show that microwave treatment is a very effective method for modifying the surface chemistry of the ACFs with the production of pyrone groups, detected by FTIR. As a result very basic carbons, with points of zero charge approximately equal to 11, are readily obtained. 相似文献
19.
Robert J. Andrews 《Carbon》2006,44(2):341-347
Single walled nanotubes have been synthesized by chemical vapor deposition from camphor, camphor analogs (camphorquinone, norcamphor, norbornane, camphene, fenchone), and various other precursors (menthone, 2-decanone, benzene, methane). The high temperature conditions (865 °C) and Fe/Mo alumina catalyst used in the syntheses are archetypal conditions for the production of single walled carbon nanotubes. It has been shown that the mechanism of tube growth is unlikely to depend upon the production of reactive five- and six-member rings, as has been previously suggested. The results suggest that the presence of oxygen in the precursor does not significantly improve the quality of tubes by etching amorphous carbon: it is suggested that the control of the flux of the precursor to the catalyst is more important in the production of high quality tubes. There is, however, evidence for different distributions of tube diameter being produced from different precursors. 相似文献
20.
Wan Mohd Ashri Wan Daud Wan Shabuddin Wan Ali Mohd Zaki Sulaiman 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2003,78(1):1-5
A series of experiments were conducted to investigate the effect of activation temperature on pore development of activated carbon produced from palm shell. Activation of the samples was carried out at 800, 850 and 900 °C for different durations ranging from 10 to 180 min. The samples were characterized using N2 adsorption for evaluation of micropores and the mercury intrusion technique for mesopore and macropore analysis. Within the range of activation temperatures studied, high burn‐off products derived from high activation temperatures tend to have larger micropore development. However, an increase in the activation temperature has no remarkable effect on mesopore and macropore development. © 2002 Society of Chemical Industry 相似文献