Nitrogen adsorption on fluorinated activated carbon fiber

Nitrogen adsorption isotherms for fluorinated activated carbon fiber (F-ACF) and fluorinated carbon black (F-CB) were measured at 77 K. Surface structures of F-ACF and F-CB were examined by _s -plot analysis using the adsorption data on the nonporous carbon black (CB) and F-CB. The surface energy of F-ACF was lower than that of ACF. The micropore structure of ACF was preserved even after fluorination, although the limiting adsorption amount and the micropore width decreased with fluorination.     

电厂废气中饱和水蒸气对活性炭变压吸附捕集CO2的影响

由于热电厂废气中含有高湿饱和水蒸气,选用疏水材料活性炭为吸附剂,利用真空变压吸附技术研究了活性炭分离电厂废气中水蒸气和二氧化碳的可行性和优越性,研究了水对CO₂捕集的影响。实验分析表明,水在活性炭上的“S”型等温吸附曲线有利于真空条件下被解吸。同时,圆锥模型描述了水蒸气在吸附床内的浓度分布。结果表明,即使水蒸气可以被活性炭吸附,但它的存在不影响CO₂的捕集。每个循环操作可在相对较短的解吸时间和较高的解吸压力下完成。实验中单床三步变压吸附工艺可以使CO₂回收率高达80%,CO₂纯度达43%。     

甲烷在活性炭上吸附平衡模型的研究

比较吸附模型分析甲烷在活性炭上吸附平衡的适用性,为吸附式天然气(ANG)的工程应用提供准确的预测模型。基于在温度268.15～338.15 K、压力0～12.5 MPa测试的甲烷在Ajax活性炭上的吸附平衡数据,选择Langmuir、Langmuir-Freundlich和Toth方程,应用非线性回归拟合方程参数后,确定绝对吸附量和甲烷吸附相态,并比较方程在不同压力区域内的预测精度。结果表明,甲烷吸附相密度随平衡温度和压力变化;由绝对吸附量确定的甲烷在Ajax活性炭上的平均等量吸附热为15.72 kJ/mol,小于由过剩吸附量的标绘结果;Langmuir、Langmuir-Freundlich和Toth方程预测结果在0～0.025 MPa的累积相对误差为6.449 8%、7.918 4%和0.910 0%,在1～10 MPa为0.491 1%、0.161 3%和0.369 4%。Toth方程在整个压力范围内的预测结果最为准确,但Langmuir-Freundlich方程在较高压力区域内具有较高的预测精度。     

甲烷在石墨化热解碳黑和活性炭上的吸附

为研究影响碳基吸附剂吸附超临界温度气体的主要因素,选择石墨化热解碳黑BP280和Ajax活性炭,分析超临界温度高压甲烷在其上的吸附平衡。应用容积法,在压力0~20.5 MPa、温度253 K~313 K测定甲烷的吸附平衡数据,并由等量吸附线标绘和亨利定律常数确定等量吸附热。引入通用吸附等温方程,再由方程的Langmuir标绘确定最大吸附容量,进而通过方程的线性化计算吸附平衡态中甲烷分子的作用能。结果表明,甲烷在两种吸附剂上的最大吸附容量均随温度而变化,并都小于液态甲烷的密度;甲烷在碳黑和活性炭上的等量吸附热分别为11.9 kJ/mol~12.5 kJ/mol和17.5 kJ/mol~22.5 kJ/mol,体现了两种吸附剂不同的表面能量分布;甲烷分子间作用能随吸附量的变化特点反映了超临界温度甲烷以类似于压缩气体状态聚集的特点和吸附剂结构上的差异。碳基吸附剂的比表面积和微孔容积是影响其储存甲烷容量的重要因素。     

活性炭液相吸附去除噻吩硫化物的研究

迄今为止,国内外降低汽油硫含量的方法主要有原料加氢脱硫、汽油加氢脱硫、溶剂抽提脱硫、催化裂化脱硫、氧化脱硫、生物脱硫、吸附脱硫及组合技术,同时一些非常规技术如膜过程脱硫、等离子体和光脱硫也在积极探索之中。     

活性炭孔隙结构对催化氧化脱除单质汞的影响

研究活性炭在硫化氢存在条件下催化氧化脱除煤气中单质汞的吸附机理和探讨提高其吸附能力的方法,在模拟煤气气氛下对3种活性炭和一种活性焦进行汞的吸附性能实验,并进一步分析活性炭(焦)的孔隙结构。用BET方程处理N₂等温吸附数据,计算比表面积;用HK法进行微孔分析;用BJH法计算中孔孔径分布。结果表明,硫化氢被催化氧化后,生成吸附在活性炭孔壁上的活性硫促进了对汞的吸附;随着活性炭微孔和中孔体积的增大,活性炭对汞的吸附能力得到提高。     

活性炭吸附CO2与其微孔体积的关系

对五种活性炭样品进行液氮温度下的N2吸附、碘吸附测定和冰点下的CO2吸附表征。结果表明,碘吸附值测定法和基于N2吸附等温线的BET方程、D-R方程,孔结构参数都不能正确反映活性炭对CO2的吸附特性;由CO2吸附等温线得到的D A模型参数也不适合分析活性炭吸附CO2特性;CO2吸附等温线的密度泛函理论（DFT）分析结果表明,CO2在活性炭上的吸附发生在极微孔内,DFT分析的微孔孔容与吸附等温线反映的吸附性能完全一致。因此,根据CO2吸附等温线的DFT模型是准确反映活性炭吸附CO2特性的表征分析方法。     

磁性活性炭的制备及其对KMn04的吸附性能

采用浸渍氮气保护焙烧法,以自制碳酸锶、氯化铁和工业活性炭为原料,制备了介孔磁性活性炭．采用红外光谱、N2吸附、X光衍射、振动样品磁强计等手段和以吸附KMnO4作为探针实验,表征了样品的性质和吸附性能．结果表明,磁性活性炭是具有较高微孔率的介孔磁性材料,其微孔率为45．74％．该材料的饱和磁化强度为19．6emu／g,矫顽力为239．7Oe,易于吸附后的磁分离,且具有一定的抗退磁能力．对KMnO4的吸附探针实验表明其吸附本质为物理吸附．Freundlich吸附等温式可描述KMnO4在磁性活性炭上的吸附平衡,准二级动力学方程是描述KMnO4在磁性活性炭上吸附的最佳吸附动力学模型．本研究有望为特种废水处理剂提供新型功能性材料．     

Preparation of biomass-derived phosphorus-doped microporous carbon material and its application in dye adsorption and CO2 capture

Microporous P-doped carbon materials are synthesized by a pyrolysis method using MCM-22 as a template, sucrose as a precursor, and phosphoric acid as phosphorus sources. The results show that the pore structure of the carbon materials can be adjusted by changing the amount of phosphoric acid and template. When the P/C molar ratio is 0.075, the obtained P-doped microporous carbon material shows excellent specific surface area up to 621 m²/g and shows a high adsorption capacity of 199.40 mg/g for crystal violet dye, with a removal rate of 98.9%. When testing the CO₂ adsorption capacity, it was found that the maximum adsorption capacity reached 63 mg/g and remained stable after 10 adsorption and desorption cycles, with excellent cycle stability. The adsorption obeys pseudo-second-order kinetic model, and the adsorption isotherm follows the Langmuir model.     

Endothermic character of toluene adsorption from supercritical carbon dioxide on activated carbon at low coverage

Recasens, P., Velo, E., Larrayoz, M.A. and Puiggené, J., 1993. Endothermic character of toluene adsorption from supercritical carbon dioxide on activated carbon at low coverage. Fluid Phase Equilibria, 90: 265-287.

Heat effects and volumetric properties are analyzed for the adsorption of toluene from supercritical carbon dioxide onto activated carbon at the limit of zero coverage, based on existing data for the system. Using values of the adsorption equilibrium constant at different temperatures as a function of fluid density, large, negative partial molar volumes for toluene in the fluid were obtained, which were previously unavailable.

Numerical integration of the differential equation that expresses the isobaric temperature dependence of the equilibrium constant, coupled with parameter optimization, enabled us to estimate the differential enthalpy of toluene adsorption onto the surface from the ideal gas at the same pressure and temperature, in addition to the enthalpy of transfer from the fluid to the surface. This is found to be large and positive near the critical conditions. Using the thermodynamic analysis of Kelley and Chimowitz, our results show that in terms of the enthalpy of transfer, the isothermal adsorption from a supercritical fluid is an endothermic process, thus explaining the retrograde behavior experimentally observed for the regeneration of carbon with supercritical CO₂ at conditions not far from the solvent's critical point.     

Nitrogen‐doped mesoporous carbon materials for oxidative dehydrogenation of propane

The CN‐15‐x series materials with different doses of SBA‐15 template and the CN‐y‐2.0 series materials with different hard templates were prepared by the hard template method with hexamethylenetetramine as the carbon and nitrogen source. The obtained mesoporous carbon materials were characterized by X‐ray diffraction (XRD), N₂ adsorption–desorption, transmission electron microscopy (TEM), Raman spectroscopy, and X‐ray photoelectron spectroscopy (XPS). The catalytic performance of propane oxidative dehydrogenation was determined. The characterization results indicate that the catalytic activity of CN‐15‐2.0 with a bipartite hexagonal ordered structure was higher than those of the other materials. The conversion of propane was 22.98%, and the selectivity toward propylene was 41.70%.     

Energetics of methane adsorption on microporous activated carbons

The influence of microporous carbon surface oxidation on energetics of methane adsorption at 308 K is discussed. Obtained adsorption heats and integral molar entropies of the adsorbate show that microporous carbon surface oxidation changes the methane adsorption process. This is probably resulted by the existence of an endothermic effect during adsorption in oxidized carbon micropores.     

树脂基球状活性炭的制备及对二氧化碳吸附性能的研究

以四种离子交换树脂（两种强碱性树脂D201和D280、两种弱碱性树脂D301G和D301R）为原料,经过磺化、炭化、活化处理制备了树脂基球状活性炭。采用TG、SEM、N₂吸附等对球状活性炭的收率、表面形貌、比表面积进行了表征,研究了所制球状活性炭对CO₂的吸附性能。结果表明,磺化处理有助提高树脂球的炭化收率;得到的四种球状活性炭对CO₂吸附性能良好,强碱性树脂球原料比弱碱性树脂球更具有优势,其中,由强碱性树脂球D201制得的树脂球状活性炭在30 ℃下对CO₂的吸附量可达2.57 mmol/g;十次循环吸附之后,树脂球仍能保持很好的CO₂吸附性能。     

氯化锂活化制备活性炭及吸附锂离子性能研究

采用化学活化法,用猪血粉为前驱体和新型活化剂氯化锂活化制备锂离子活性炭（LB-AC）并进行吸附锂离子研究。用氯化锂对猪血粉进行活化后我们得到比表面积为695 m2?g-1,总孔体积为0.3 cm3?g-1的LB-AC。通过扫描电子显微镜、元素分析、X 射线衍射分析和红外光谱分析等分析手段对LB-AC表面形貌和表面基团进行表征。吸附?解吸实验结果表明,随着温度升高,锂离子的吸附容量随之增加,表明LB-AC对锂离子的吸附是一种吸热反应。当温度增加至35 ℃和45 ℃时,其吸附容量分别增加至1.41 mg?g-1和1.52 mg?g-1。锂离子的初始浓度增加,吸附容量也增加。锂的脱附随着盐酸浓度的升高而增加。LB-AC对锂离子的选择性很高,且吸附剂在碱性环境下吸附容量更高,在酸性环境下基本不吸附。     

简单芳香化合物的结构和性质对活性炭吸附行为的影响

用静态吸附法考察了一种活性炭对废水中四种简单芳香化合物的吸附行为,并用Langmuir模型对吸附数据进行了拟合。结果表明,Langmuir模型可以近似地描述这些芳香化合物在该活性炭上的吸附行为。芳香化合物的极性及其在水中的溶解度对其在活性炭上吸附的影响较大,芳香化合物与活性炭之间的π-π色散作用对吸附的影响很小。     

四苯硼钠在活性炭表面吸附过程的疏水相互作用

In this paper, the adsorption characteristics of sodium tetraphenylborate(NaBPh4) on activated carbon at 298.2,303.2,308.2,313..2 and 323.2 K was studied.The results show that the adsorption isotherm of NaBPh4 on activated carbon at different temperatures could be described using Langrnuir equation. Furthermore, the standard Gibbs energy, enthalpy, entropy and hydrophobic interaction Gibbs energy for the adsorption of NaBPh4 on activated carbon were studied, and the result shows that the hydrophobic interaction of BPh4^- ion plays the most important role for the transfer of NaBPh4 from water to activated carbon surface.     

The influence of nitrogen sources on nitrogen doped multi-walled carbon nanotubes

A range of nitrogen doped carbon nanotubes (N-CNTs) was produced by a nebulised floating catalyst method at 850 °C using a mixture of toluene and 1-8% nitrogen containing reagents (a range of amines and amides). The carbon nanotube (CNT) products were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA), CHN analysis as well as Raman spectroscopy. Differences due to the different N containing reagents were noted but in general all reagents gave aligned CNTs that at low concentration (1%) were longer and wider than those produced without nitrogen. Increased N content in the reactant mixture gave doped tubes that became shorter and showed more disorder. Treatment of the N-CNTs with nitric acid (microwave, 30 min) gave samples that were chemically modified by the acid (loss of alignment, narrower tubes and more facile oxidation). It appears in general that the amount of N in the nitrogen containing reagent is more important than the source and type of the N atoms used as revealed by trends in the morphology (diameter, length) of the N-CNTs produced.     

超临界甲烷在活性炭上的吸附平衡分析

为分析由吸附平衡时的热力参数确定吸附量、吸附模型和等量吸附热精度的影响因素,选择在温度268.15~338.15 K和压力0~13.5 MPa测试的甲烷在Ajax活性炭上的吸附平衡数据,通过引入甲烷分子可进入活性炭吸附空间内的容积和可以不考虑甲烷在孔内吸附的临界孔宽的概念,依据甲烷在吸附平衡前后的总量守恒,确定甲烷在吸附池内的总量、绝对吸附量和过剩吸附量三者之间的关系式。结果表明,在引入吸附质分子可进入吸附空间内的容积和临界孔宽后,经由活性炭的孔径分布(PSD),可以准确计算甲烷在活性炭上的过剩吸附量;应用实验数据非线性回归Toth方程参数后,可由Gibbs关于吸附的定义确定甲烷在活性炭上的绝对吸附量。比较结果时发现,由于未考虑本体相中甲烷分子对吸附甲烷分子的影响,采用过剩吸附量的等量吸附线标绘确定的等量吸附热数值偏高,工程应用时应由绝对吸附量来确定等量吸附热。     

载铜球形活性炭的制备及其吸附脱硫性能的研究

以122型弱酸性酚醛系阳离子交换树脂为炭前驱体,经过Cu²⁺交换、炭化和CO₂活化等过程制备得到负载金属铜的球形活性炭,对其进行了SEM、XRD、AAS和BET表征,采用动态吸附实验研究了其对模拟汽油中噻吩类硫化物的吸附性能,并且考察了甲苯和环己烯对其吸附性能的影响,对吸附脱硫机理进行了初步研究。结果表明,载铜球形活性炭上Cu以单质形态存在,并主要与硫原子产生配位作用,提高了对噻吩类硫化物的吸附性能,对噻吩(T)、3-甲基噻吩(MT)、2,5-二甲基噻吩(DMT)和苯并噻吩(BT)的饱和硫容依次为0.938、1.230、1.581和3.744 mg/g,吸附选择性依次为T < MT < DMT < BT。模拟汽油中加入甲苯和环己烯后,饱和硫容分别下降了77%和56%,这是甲苯和环己烯通过π电子与Cu发生作用,从而与硫化物产生竞争吸附导致的。     

Correlation of fractal pore-size distribution of activated carbon fiber with its adsorption for low concentration benzene vapor

Fractal pore-size distribution K(x) is given based on J(x) function proposed by Jaronic. Activated carbon fibers (ACF) with different surface areas are characterized by using two functions mentioned above. The present work studies the fractal pore-size distribution of ACF and adsorption isotherms of nonpolar benzene vapor on ACF, and thereby reveals the correlation between them.