低挥发性有机物脱附活化能估算模型

提出了一种新的低挥发性有机物程序升温脱附(TPD)活化能估算模型.与经典 TPD 模型相比,所提出的新的 TPD理论模型不仅考虑了脱附过程中存在的吸附质分子再吸附现象的影响,而且还考虑了脱附分子在吸附剂孔内扩散的影响.通过 TPD 实验,运用所建立的活化能估算模型,技术测定了二苯并呋喃在 Norit RB1、Monolith 和 Chemviron三种活性炭上的脱附活化能.结果表明经典TPD 模型所估算出来的二苯并呋喃的活化能要比非线性 TPD 模型估算结果偏高约8.2%～9.6%,这表明脱附过程中存在吸附质分子再吸附现象和内扩散过程对脱附活化能有一定的影响.     

有序介孔碳对低浓度气相萘的吸附特性分析

对3种常见有序介孔碳(OMCs)吸附脱除典型气相多环芳烃——萘进行了研究。分别采用吸附等温线模型(Langmuir、Freundlich、Sips)和恒定浓度波动力学模型对吸附等温线和穿透曲进行拟合分析。采用程序升温脱附法通过失重曲线分析了吸附剂的再生性能。结果表明:Langmuir模型和Sips模型能很好地描述低浓度气相萘在OMCs上的静态吸附行为(R~299%),吸附量呈CMK-5CMK-3FDU-15排列。恒定浓度波动力学模型具有较高的拟合度,介孔促使3种吸附剂对萘分子具有较高的吸附扩散系数。具有微通孔结构的CMK-5和FDU-15表现出更好的再生性能。综合吸脱附动力学分析,CMK-5在3种吸附剂中表现出更好的应用潜能。     

有序介孔碳对低浓度气相萘的吸附特性分析

对3种常见有序介孔碳（OMCs）吸附脱除典型气相多环芳烃--萘进行了研究。分别采用吸附等温线模型（Langmuir、Freundlich、Sips）和恒定浓度波动力学模型对吸附等温线和穿透曲进行拟合分析。采用程序升温脱附法通过失重曲线分析了吸附剂的再生性能。结果表明：Langmuir模型和Sips模型能很好地描述低浓度气相萘在OMCs上的静态吸附行为（R² > 99%），吸附量呈CMK-5 > CMK-3 > FDU-15排列。恒定浓度波动力学模型具有较高的拟合度，介孔促使3种吸附剂对萘分子具有较高的吸附扩散系数。具有微通孔结构的CMK-5和FDU-15表现出更好的再生性能。综合吸脱附动力学分析，CMK-5在3种吸附剂中表现出更好的应用潜能。     

磁性树脂和活性炭混合吸附剂吸附腐殖酸研究

采用磁性树脂和活性炭混合吸附剂对腐殖酸(HA)进行吸附,研究不同质量比混合吸附剂对HA的吸附,利用吸附动力学、吸附等温线和动态吸附脱附实验对树脂吸附、脱附过程进行分析。结果表明,当磁性树脂和活性炭的质量比为9:1时,混合吸附剂对HA的吸附容量最高,吸附过程符合准2级动力学模型。混合吸附剂对HA的吸附等温线更适合Langmuir模型,25℃时拟合饱和吸附量可达135.1 mg/g。动态吸附过程中,混合填柱固定床对HA的吸附要优于分层填柱,体积比1:1质量分数10%的NaOH、质量分数10%的NaCl对2种吸附固定床能快速脱附。     

程序升温脱附活化能估算新模型

以吸附过程本征动力学模型为基础，提出了一种新的TPD非线性活化能估算模型.与经典TPD模型相比，这种新的TPD理论模型考虑了脱附过程中存在的吸附质分子再吸附现象的影响，更接近实际的脱附过程.采用TPD实验技术测定了二苯并呋喃在Norit RB1、Monolith和Chemviron 3种活性炭上、不同升温速率下的程序升温脱附图谱.以这些TPD图谱为基础，分别采用经典TPD模型和TPD非线性模型计算了二苯并呋喃在3种活性炭上的脱附活化能.结果表明，经典TPD模型所估算出来的二苯并呋喃的活化能要偏高TPD非线性模型估算结果约8％～12％，脱附过程中存在吸附质分子再吸附现象对脱附活化能有较大的影响.     

中高温环境下VOCs在活性炭上的吸附性能研究

选用3种商用活性炭及其分别经HCl溶液和KOH溶液浸渍改性的商用活性炭,研究中高温烟气环境下,反应空速、吸附温度对挥发性有机物（VOCs）吸附性能的影响,以及VOCs种类、吸附剂特性等与VOCs吸脱附效果的关系。研究发现：空速对吸附穿透时间影响较大,但对饱和吸附量影响不显著。吸附温度与VOCs浓度对饱和吸附量存在较大影响,150℃时甲苯的饱和吸附量仅能达到90℃时的40％。高沸点吸附质更易被吸附,更难被脱附。     

活性碳填料在挥发性有机物分析中替代TENAX的应用研究

热脱附-气相色谱质谱分析挥发性有机物(VOCs)是目前应用最广泛,也是最便捷的VOCs分析方法。该方法的关键在于采用合适的填料,能够对空气中的VOCs进行有效的捕集和脱附。主要研究了新型国产活性碳在挥发性有机物(VOCs)分析中替代TENAX填料的可能性。通过残留率、重复性和线性测试,对活性炭吸附解析VOCs的能力进行探究。选择9种VOCs,利用热脱附-气质分析法对活性炭和TENAX填料的吸附性能进行比较,来研究活性碳替代TENAX的可能性。     

吸附挥发性有机化合物树脂的高效微波再生过程

主要研究应用微波辐射再生高聚物吸附树脂.论述了微波加热的优点和微波脱附的原理,以乙醇为吸附质研究了吸附和微波辐射再生吸附剂过程.进行了正流微波辐射脱附和逆流微波辐射脱附实验,测定了微波脱附流出曲线和床层的温升曲线,并与传统的热脱附流出曲线和在不同加热速率下得到的床层温升曲线进行比较.实验结果表明：微波脱附比热脱附脱附速度更快,效率更高;高聚物吸附树脂类吸附剂对微波是半透明的,它对微波的吸收能力随着温度的升高而下降,因此,在微波辐射下,吸附剂床层吸收微波的能力也随着床层温度的升高和吸附质的脱附而减弱,床层最终温度不超过84℃,可使吸附剂的结构和性能不会被破坏和受影响,这有利于吸附剂的循环使用.微波在脱附和吸附剂再生中有很好的应用前景.     

分形BET吸附模型

本文提出了一个改进的分形ＢＥＴ吸附模型。用此模型分析水在新型干燥剂上的吸附平衡和文献［８］中水在活性氧化铝上的平衡吸附数据。结果表明：所提出的模型能在整个相对蒸汽压力范围内描述水在吸附剂上的吸附平衡行为；脱附等温线与吸附等温线之间的差别可归结于吸附质的单层吸附。     

中高温环境下VOCs在活性炭上的吸附性能研究

选用3种商用活性炭及其分别经HCl溶液和KOH溶液浸渍改性的商用活性炭,研究中高温烟气环境下,反应空速、吸附温度对挥发性有机物(VOCs)吸附性能的影响,以及VOCs种类、吸附剂特性等与VOCs吸脱附效果的关系。研究发现:空速对吸附穿透时间影响较大,但对饱和吸附量影响不显著。吸附温度与VOCs浓度对饱和吸附量存在较大影响,150℃时甲苯的饱和吸附量仅能达到90℃时的40%。高沸点吸附质更易被吸附,更难被脱附。     

固体酸催化剂脱附活化能动力学模型研究及酸强度表征

基于脱附动力学，确定了脱附活化能动力学模型方程，建立了基于一套程序升温脱附(TPD)数据确定固体酸催化剂脱附活化能的动力学模拟方法。不同温度活化的催化剂TPD实验数据模拟计算结果指出，催化剂的脱附过程符合2级脱附规律；随着活化温度的提高，催化剂的脱附活化能（或酸强度）呈先增大后降低的变化趋势。比较单套数据法和多套数据法的计算结果可知，两种方法测定的脱附级数相同，各活化催化剂的脱附活化能有相似的变化趋势，单套数据法具有操作简便和结果可靠的优点。     

Simulating Temperature Programmed Desorption of Oxygen on Pt(111) Using DFT Derived Coverage Dependent Desorption Barriers

The dissociative adsorption energy of oxygen on Pt(111) is known to be coverage dependent. Simple Redhead analysis of temperature programmed desorption (TPD) experiments that assumes a coverage independent desorption barrier can lead to errors in estimated properties such as desorption barriers and adsorption energies. A simple correction is to assume a linear coverage dependence of the desorption barrier, but there is usually no formal justification given for that functional form. More advanced TPD analysis methods that are suitable for determining coverage dependent adsorption parameters are limited by their need for large amounts of high quality, low noise data. We present a method to estimate the functional form of the coverage dependent desorption barrier from density functional theory calculations for use in analysis of TPD spectra. Density functional theory was employed to calculate the coverage dependence of the adsorption energy. Simulated TPD spectra were then produced by empirically scaling the DFT based adsorption energies utilizing the Brønstead–Evans–Polyani relationship between adsorption energies and desorption barriers. The resulting simulated spectra show better agreement with the experimental spectra than spectra predicted using barriers that are either coverage-independent or simply linearly dependent on coverage. The empirically derived scaling of the desorption barriers for Pt(111) is shown to be useful in predicting the low coverage desorption barriers for oxygen desorption from other metal surfaces, which showed reasonable agreement with the reported experimental values for those other metals.     

Effect of heating profile on desorption curve in temperature programmed desorption analysis: case study of acid sites distribution of SAPO-34

Comparison of the traditional linear heating method of TPD with an original stepwise heating scheme was reported for the first time. Stepwise heating TPD was carried out by keeping the temperature constant as soon as ammonia desorption signal rises until the signal returns to the baseline. More ammonia desorption peaks on a SAPO-34 catalyst were identified using TPD with stepwise heating. The effect of temperature ramp on desorption peak broadening in TPD curve was also addressed. The more distinct ammonia desorption peaks in stepwise TPD indicates that ammonia adsorbs in about five or six different ways on SAPO-34, and attribution of different adsorptions may be explained considering some known features of SAPO’s acidity; including adsorption on the bridge hydroxyl groups Brønsted acid sites with different acid strength resulting from different silicon environment of SAPO molecular sieves, adsorption on terminal hydroxyl groups Brønsted acid sites, and by multiple adsorption of ammonia on acid sites.     

Heterogeneity of Adsorption Sites and Adsorption Kinetics of n-Hexane on Metal-Organic Framework MIL-101(Cr)

abstract The heterogeneity of adsorption sites and adsorption kinetics of n-hexane on a chromium terephthalate-based metal-organic framework MIL-101(Cr) were studied by gravimetric method and temperatu...     

Temperature programmed desorption of <Emphasis Type="Italic">n</Emphasis>-hexane and <Emphasis Type="Italic">n</Emphasis>-heptane from MFI and FAU zeolites

TPD studies of n-hexane and n-heptane from NaX, Y and ZSM-5 (Na⁺ or H⁺ exchanged) in the experimental system with a TCD detector were performed, using pure He or He/n-alkane mixture as a carrier gas. The TPD profiles with one desorption peak for Y and two peaks for ZSM-5, measured using He/hydrocarbon mixture, were similar to the previously reported equilibrated thermodesorption results. TPD profiles were accurately fitted with a model based on the equilibrium control of the desorption and the adsorption functions derived from the Langmuir or dual site Langmuir isotherms.     

Effect of textural property of coconut shell-based activated carbon on desorption activation energy of benzothiophene

In this work, the effect of the textural property of activated carbons on desorption activation energy and adsorption capacity for benzothiophene (BT) was investigated. BET surface areas and the textural parameters of three kinds of the activated carbons, namely SY-6, SY-13 and SY-19, were measured with an ASAP 2010 instrument. The desorption activation energies of BT on the activated carbons were determined by temperature-programmed desorption (TPD). Static adsorption experiments were carried out to determine the isotherms of BT on the activated carbons. The influence of the textural property of the activated carbons on desorption activation energy and the adsorption capacity for BT was discussed. Results showed that the BET surface areas of the activated carbons, SY-6, SY-13 and SY-19 were 1106, 1070 and 689 m²g^-1, respectively, and their average pore diameters were 1.96, 2.58 and 2.16 nm, respectively. The TPD results indicated that the desorption activation energy of BT on the activated carbons, SY-6, SY-19 and SY-13 were 58.84, 53.02 and 42.57 KJ/mol, respectively. The isotherms showed that the amount of BT adsorbed on the activated carbons followed the order of SY-6 > SY-19 > SY-13. The smaller the average pore diameter of the activated carbon, the stronger its adsorption for BT and the higher the activation energy required for BT desorption on its surface. The Freundlich adsorption isotherm model can be properly used to formulate the adsorption behavior of BT on the activated carbons.     

Adsorption of Propene in the Presence and Absence of Oxygen or Nitric Oxide on Pt-Loaded ZSM-5, Beta, Y, and Ferrierite Zeolites

Adsorption and desorption of NO and propene on pure and platinum-loaded ZSM-5, Beta, Y and Ferrierite zeolites have been studied by FTIR and temperature programmed desorption (TPD). Platinum-loaded ZSM-5 and Beta are found to have a good adsorption capacity for hydrocarbons and NO at low temperatures. HC-SCR on Pt-zeolites is a promising NO abatement method.     

噻吩在CeY分子筛上的吸附行为

采用智能质量分析(IGA)和程序升温脱附和微分程序升温脱附（TPD/DTPD）法研究了噻吩在CeY上的热脱附行为和吸附热力学,并和NaY进行对比。发现噻吩在CeY分子筛上有很好的选择性吸附,噻吩和CeY分子筛之间的吸附主要是金属离子和硫原子的化学键力作用,而在NaY上的吸附作用属于分子间力作用。吸附热力学也证明了噻吩在CeY上既有物理吸附作用也有强的化学吸附作用。     

Investigation of the water-gas shift reaction using temperature-programmed desorption

The water-gas shift reaction has been investigated by the temperature-programmed desorption (TPD) of reaction components over a commercial low-temperature catalyst. It has been found that the oxidation state (and consequently the activity) of the catalyst is strongly influenced by the composition of the gaseous mixture. The adsorption capacity of catalysts decreases in the order: H₂O CO₂CO; hydrogen does not adsorb. The existence of two types of sites for carbon oxides adsorption has been found experimentally. A further type of storage (inactive) sites for water exists. On the basis of experimental results, model equations for TPD of H₂O, CO₂ and CO were derived. Models best fitting the experimental data were based on the assumption of a non-uniform heterogeneous surface of the catalyst.