甲烷在高表面炭质吸附剂上的低温吸附性能研究

液化天然气汽车(LNGV)用于城市小轿车时,因夜间停驶或较长时间停运时,储罐内LNG的蒸发可能迫使燃料储存系统安全阀开启放气,增加小型LNGV的安全环境风险。结合LNGV燃料储存系统的主要特点,开展了低温低压下甲烷在高表面炭质吸附剂(SYJ-2)上的吸附性能研究。结果表明,在温度238～161K,压力1.5MPa下,吸附剂对甲烷的吸附量为0.16～0.3g/g,即82～153mL/mL。吸附天然气(ANG)可望用于LNGV燃料储存系统,以增加LNGV燃料储存系统的安全性。

菌丝体表面分子印迹吸附剂的选择性吸附

采用制备得到的菌丝体表面分子印迹吸附剂,系统研究了菌丝体表面分子印迹吸附剂对模板金属离子的吸附选择性。结果表明:与非印迹吸附剂相比,以Ni2+为模板制备的菌丝体表面分子印迹吸附剂,对Ni2+、Cu2+与Cr3+的吸附速率和吸附容量都有较大幅度的提高。对于含有Ni2+的金属离子混合溶液,菌丝体表面分子印迹吸附剂对Ni2+的吸附容量和选择性都比另一种金属离子(如Cr3+和Cu2+)明显提高;与非印迹吸附剂相比,印迹吸附剂对非模板金属离子Cr3+和Cu2+的选择性明显降低。

高比表面积炭质吸附剂吸附性能评价方法的研究

采用热重天平和吸附剂评价装置测试了高比表面积炭质吸附剂对甲烷的吸附性能,论述了其影响因素和相关校正过程。测试结果表明,在相同的甲烷气体压力下,质量吸附量不随吸附剂质量变化而改变,压力越高,其误差越小,当压力为4 90MPa时,质量吸附量误差不足0 8%;体积吸附量的校正误差不超过1%。

表面活性剂在低能固体表面上的吸附 Ⅲ.聚苯乙烯胶乳粒子对阴离子表面活性剂的吸附

在无乳化剂的条件下合成了粒径均匀的聚苯乙烯胶乳.发展了应用表面张力计测定吸附等温线的连续平衡法,得到不同盐浓度和温度下聚苯乙烯胶乳对十二烷基硫酸钠和十二烷基苯磺酸钠的吸附等温线.它们属于Giles分类的L_2型或L_4型,采用两阶段吸附模式讨论了吸附机理、吸附层结构及等温线类型变化的规律。

Y型分子筛酸性对其吸附脱硫性能影响的研究

燃料油的深度脱硫一直是国内外研究的热点。传统加氢脱硫技术应用于汽油馏分的关键是如何实现最大限度的脱硫而不使汽油辛烷值降低．吸附脱硫技术因操作简单且无辛烷值损失而有望成为最有前途的深度脱硫技术之一。目前，对金属离子改性的Y型分子筛吸附脱硫的研究已取得很多基础性的研究成果，但是在金属离子交换的同时，往往在分子筛内引入不同种类的酸性中心，吸附剂酸性对吸附脱硫的影响一直被忽略或关注较少。本论文以液相离子交换法制备Ce（IV）Y、AgY，以原位红外光谱法探索吸附剂的酸性对噻吩、环己烯和甲苯3种吸附质的吸附模式的影响，并对这两种吸附剂在不同体系中的吸附脱硫性能做了系统考察，揭示酸性对吸附剂脱硫性能的影响方式。本文研究表明：NaY吸附剂表面无酸性，Ce（Ⅳ）Y和AgY表面既有B酸中心，又有L酸中心，但前者以中等强度以上的B酸中心为主，后者酸强度分布广泛的L酸中心为主。噻吩、甲苯和环己烯3种吸附质在Ce（IV）Y和AgY上的吸附模式存在着差别。Ce（IV）Y吸附剂的强B酸中心均引起噻吩和环己烯吸附方式的变化，生成相应的质子化产物，对甲苯的吸附方式无影响。Ce（IV）Y吸附剂对噻吩具有更好的吸附选择性，主要是因为S—Ce＋＋直接作用起着主要脱硫作用；甲苯对噻吩吸附的影响主要是竞争吸附位；烯烃与噻吩共存时，会在Ce（IV）Y表面的B酸位引发烷基化反应或者烯烃分子自身聚合，从而导致其脱硫率显著下降。Ce（IV）Y对3种不同组成模型油的吸附等温线表明，环己烯和甲苯的存在显著降低了吸附剂的吸附硫容。很明显Ce（IV）Y表面的酸性使其吸附脱硫性能降低。而对AgY吸附剂来说，酸中心的存在未发现对噻吩、环己烯和甲苯的吸附产生影响，3种吸附质均发生兀络合作用。当模型油中含有少量竞争物时，AgY对噻吩仍具有较好的吸附选择性，主要是因为噻吩分子与Ag＋＋之间的“络合作用；大量竞争物存在，因相同的吸附方式而使得竞争物与噻吩之间形成强烈的竞争吸附，导致脱硫效果显著下降。AgY表面的B酸并未引发烷基化反应或是烯烃的聚合，这说明AgY吸附剂表面的酸性并未对其吸附脱硫造成影响。

Low-temperature collecting performance of a new combined collector on scheelite flotation

The reduced ability of fatty acids to dissolve and disperse at low temperatures limits their effectiveness in winter applications.In this study,a green and environment-friendly reagent,polyethylene glycol 2000(PEG-2000),was used to evaluate its effect on the collecting performance of sodium oleate during scheelite flotation at low temperatures.The effect of PEG-2000 on the flotation of scheelite with the collector sodium oleate(NaOL)was studied by flotation tests,surface tension tests,infrared spectral analysis,and zeta potential measurements.Flotation tests showed that adding PEG-2000 can enhance the collecting ability of NaOL on scheelite at low temperature(5℃).The recovery of scheelite with the mixed collector of PEG-200 and NaOL is 4.39%higher than that with NaOL only.The surface tension tests,infrared spectral analysis and zeta potential measurements revealed that PEG-2000 and OL^(−)are co-adsorbed on the scheelite surface at low temperatures.The presence of PEG-2000 promoted the increase of the adsorption concentration of oleate ions(OL^(−))on the scheelite surface.The reason was that PEG-2000 has a shielding effect on the electrostatic repulsion between the OL^(−)groups,which changes the micellar configuration of OL^(−)in the solution system and makes the OL^(−)gather more tightly on the surface of scheelite,leading to the enhancement of its hydrophobicity.This discovery provides a reference for the development of collecting reagents for efficient flotation recovery of scheelite under low temperature environment.

Performance of branched-chain extended surfactant mixed with zwitterionic or cationic surfactant

2-Hexyl-1-decanol was used as the main material to prepare a block-polyether sulfonate extended surfactant(IC_(16)P_(6)E_(6)S).The solubility and surface active properties of IC_(16)P_(6)E_(6)S were evaluated,and then the IC_(16)P_(6)E_(6)S was mixed with a cationic surfactant hexadecyl trimethyl ammonium bromide(CTAB)and a zwitterionic betaine surfactant(HAB),respectively.The effects of mixing ratios of IC_(16)P_(6)E_(6)S∶HAB and IC_(16)P_(6)E_(6)S∶CTAB on the hydrodynamic diameter and interfacial properties were discussed.The emulsification,adsorption and laboratory core displacement experiments of the binary system were tested.The results showed that the critical micelle concentration(cmc)of IC_(16)P_(6)E_(6)S in distilled water was 0.1 mmol/L and the surface tension at cmc(γcmc)was 28.53 mN/m.IC_(16)P_(6)E_(6)S showed strong synergistic effects with HAB and CTAB,and the mixed systems could effectively reduce the interfacial tension compared with single surfactants.The mixed systems with n(IC_(16)P_(6)E_(6)S)∶n(HAB)of 1∶1 and n(IC_(16)P_(6)E_(6)S)∶n(CTAB)of 1∶3 could maintain ultra-low interfacial tension(in the order of magnitude of 10^(-3)mN/m)in the salinity range of 1%-7%NaCl and low interfacial tension(in the order of magnitude of 10^(-2)mN/m)in the salinity range of 3%-7%NaCl,respectively.With the increase of salinity,the emulsion formed by the mixed surfactant system underwent the phase transition process from WinsorⅠto WinsorⅢand then to WinsorⅡ.The emulsion of mixed IC_(16)P_(6)E_(6)S/HAB system had more middle-phase emulsion volume than that of the mixed IC_(16)P_(6)E_(6)S/CTAB system,and the former emulsion system was more stable.The mixed IC_(16)P_(6)E_(6)S/HAB system also had good solubilization effect,and the amount of oil solubilization was up to 43 mL/g.Meanwhile,it had good adsorption resistance.Compared with water flooding,the depressurization rate could reach 25.00%and the recovery could be enhanced by 11.75%,indicating that the IC_(16)P_(6)E_(6)S/HAB system was more conducive to the depressurization and injection enhancement for low-permeability reservoirs.

浅谈菌丝体表面分子印迹吸附剂的选择性吸附

通过制备的方法获得菌丝体表面分子印迹吸附剂,本文系统的分析和探讨了针对模板金属离子菌丝体表面分子印迹吸附剂的吸附选择性。通过实验研究证明,菌丝体表面分子印迹吸附剂如果是以Ni2+为模板制备的,相对于非印迹吸附剂来讲,其对Cr3+、Cu2+、Ni2+的吸附容量以及吸附速率的提高幅度都是非常大的。而菌丝体表面分子印迹吸附剂相对于具有Ni2+金属离子混合溶液来讲,其对Ni2+的选择性以及吸附容量要比含有诸如Cu2+以及Cr3+的金属离子提高的都要明显很多;印迹吸附剂相对于非印迹吸附剂来讲,其在吸附非模板金属离子Cu2+以及Cr3+时具有明显降低的选择性。

Comparative studies on flotation of aluminosilicate minerals with Gemini cationic surfactants BDDA and EDDA

Gemini quaternary ammonium salt surfactants, butane-a, co-bis（dimethyl dodeculammonium bromide） （BDDA） ethane-a, fl-bis（dimethyl dodeculammonium bromide） （EDDA） were adopted to comparatively study the flotation behaviors of kaolinite, pyrophyllite and illite. It was found that three silicate minerals all exhibited good floatability with Gemini cationic surfactants as collectors over a wide pH range, while BDDA showed a stronger collecting power than EDDA. FTIR spectra and zeta potential analysis indicated that the mechanism of adsorption of Gemini collector molecules on three silicate minerals surfaces was almost identical for the electronic attraction and hydrogen bonds effect. The theoretically obtained results of density functional theory （DFT） at B3LYP/6-31G （d） level demonstrated the stronger collecting power of BDDA presented in the floatation test and zeta potential measurement.

Study on catalyst for pyridine synthesis

The synthesis of pyridine from aldehydes and ammonia was performed over ZSM-5 catalyst. The catalytic activity in reaction was correlated with the acidity of the zeolite catalysts. A few of ZSM-5 (m(SiO2)/m(Al2O3)=120) were prepared and modified with Co2+, Fe3+. The surface acidity was determined by Py-IR technique. It was found that CoZSM-5 and FeZSM-5 have fewer Lewis acid sites than HZSM-5. The decrease of Lewis acid sites leads to decreasing the ability of NH3 adsorption, this phenomenon insures that there are adequate acid sites discovering and reacting with aldehydes. It is advantageous to the reaction. By using a CoZSM-5 catalyst, the yields of pyridine base can reach 78%. The study provides a theoretical base for preparing high activity and high selective catalyst for pyridine synthesis.

A Research Note on the Adsorption of CO2 and N2

Experiments were made for the adsorption of CO2 and N2 on typical adsorbents to investigate the effects of porous structure and surface affinity of adsorbents as well as those of adsorption temperature and pressure that might cause the variation of adsorption mechanism. It is shown that polar surface tends to enlarge the adsorption difference between CO2 and N2, and the difference is more sensitive to temperature than the adsorbents with non-polar surface. The adsorbents with non-polar surface are not much sensitive to the effect of water vapor, though the water vapor interferes the separation remarkably. The separation coefficient linearly increases with the micro- pore volume per unit surface area of activated carbons, but no rule is shown on mesoporous silicon materials. The function of adsorption mechanism on the separation is not as much as expected.

Electrochemical study on adsorption behavior of surfactants at β-2CaO·SiO2/NaAlO2 interface

β-2CaO＇SiO2 was obtained with analytical grade reagents. Polyethylene glycol （PEG）, sodium polyacrylate （PAAS） and their mixture were used to inhibit the decomposition of β-2CaO·SiO2 in sodium aluminate solution. The potential of solid-liquid interface and the adsorption mechanism were studied by the methods of Zeta potential measurement and XPS. The results indicate that PEG and PAAS have synergistic effect on the inhibition of secondary reaction. The inhibitory effect is the best when the volume ratio of PAAS to PEG is 1：1 and the total concentration is 12.5 mg/L. PAAS adsorbs on the surface of β-2CaO-SiO2 by the formation of --COOCa coordinate bond, and the negative charge enters into Stem layer, which results in the decrease of particle potential and the obvious change of binding energy of Ca 2p, Si 2p and O Is. PEG only physically adsorbs on the surface ofβ-2CaO·SiO2, and had little effect on particle potential and binding energy of Ca 2p, Si 2p and O Is.

Adsorption of Metsulfuron and Bensulfuron on a Cationic Surfactant-Modified Paddy Soil

Adsorption isotherms of metsulfuron and bensulfuron on a hexadecyltrimethylammonium （HDTMA） bromide-modified paddy soil under different ionic strengths, with divalent cation Cu^2＋, or having different pH were studied to describe their adsorptive behavior, and to try to explain the adsorption process of a sulfonylurea compound with a carbamoylsulfamoyl group in the modified soil environment. All the adsorption isotherms fitted the Freundlich equation well, and the HDTMA treatment of paddy soil dramatically enhanced adsorption capacity of metsulfuron or bensulfuron. Also, an increase of ionic strength and the addition of divalent heavy metal cation Cu^2＋ on the HDTMA-modified paddy soil increased the adsorption of metsulfuron or bensulfuron. Additionally, for metsulfuron and bensulfuron in the aqueous phase, adsorption capacity of the HDTMA-modified paddy soft gradually increased with decreasing pH.

Modeling of mass transfer characteristics of bubble column reactor with surfactant present

Danckwert’s method was used to determine the specific interfacial area, a, and the individual mass transfer coefficient, kL, during absorption of CO2 in a bubble column with an anionic surfactant in the carbonate-bicarbonate buffer solution and NaAsO2 as catalyst, the presence of which decreases the specific interfacial area and the individual mass transfer coefficient. The specific interfacial area and the individual mass transfer coefficient increase with increasing su- perficial gas velocity. The specific interfacial area decreases whereas the individual mass transfer coefficient increases with increasing temperature. The results of experiments were used to determine the dependence of a, kL, and kLa on the surface tension, the temperature of the absorption phase, and the superficial velocity of the gas. The calculated results from the correlation were found to be within 10% deviation from the actual experimental results.

Lead Removal from Aqueous Solutions Using Novel Gel Adsorbent Synthesized from Natural Condensed Tannin

Lead has caused serious environmental pollution due to its toxicity, accumulation in food chains and persistence in nature. In this paper, removal of lead from aqueous solutions is investigated using a novel gel adsorbent synthesized from natural condensed tannin. The novel adsorbent performs in aqueous solutions as a weak base with valid basic groups of 1.2mmol·g-1 tannin gel particles and therefore results in the elevation of pH value of aqueous solutions. Even when initial pH is 3.6, final pH at equilibrium can climb up to 6.5 that is above the pH value for Pb(OH)2 precipitation formation and then lead can be removed from wastewater by this so-called surface precipitation. The adsorption isotherm can be expressed by the Langmuir equation and the maximum capacity for adsorption of Pb is up to 92 mg·g-1 (based on dry adsorbent) when initial pH value is 3.6. Hence, the adsorbent does offer favorable properties in lead removal with respect to its high adsorption capacity at low initial pH value, which is advantageous to lead removal from acidic wastewater. A model is put forward to describe the individual adsorption phenomenon of the tannin gel adsorbent.

Adsorption of Fe on GaAs（100）Surface

The adsorption of one monolayer Fe atoms on an ideal GaAs (100) surface is studied by using the self-consistent tight-binding linear muffin-tin orbital method. The Fe adatom chemisorption on Ga- and As-terminatedsurface are considered separately. A monolayer of S atoms is used to saturate the dangling bonds on one of the supercellsurfaces. Energies of adsorption systems of an Fe atom on different sites are calculated, and the charge transfers areinvestigated. It is found that Fe-As interaction is stronger than Fe-Ga interaction and Fe atoms prefer to be adsorbed onthe As-terminated surface. It is possible for the adsorbed Fe atoms to sit below the As-terminated surface resulting inan Fe-Ga-As mixed layer. The layer projected density states are calculated and compared with that of the clean surface.

Characteristics of Amine Surfactant Modified Peanut Shell and Its Sorption Property for Cr（VI）

Modified peanut shell （MPS） was prepared by amination reaction with peanut shell （PS） as the starting material The sorption of Cr（VI） oxyanions on MPS in static and column tests were investigated. In addition, the sorption isotherm and kinetic models were applied to confirm the sorption capacity and the sorption mechanisms. BET surface area anysis showed the physicochemical characterist!cs of the samples. The results of zeta potential,Fourier transform infrared （FT-IR） and Raman spectra analysis illustrated that chemical adsorption and ion exi change are the potential sorption mechanism. The static sorption test showed that the maximum sorption capacity （qm） of MPS for Cr（VI） increased with temperature, which indicated that the Cr（VI） sorption rocess was endothermic. The saturated sorption capacity of Cr（VI） in the colunm sorption test was 138.34 mg.g-1, which accounted for 93.9% of the qmax at 25 ℃. The regeneration capacity of MPS was evaluated using HC1 solution as an eluent. The high regeneration efficiency （82.6%） validated the dominance of the ion exchange mechanism in the Cr（VI） sorption process with C1ions displacing Cr（VI） oxyanion on MPS. The Langmuir isotherm model showed a higher correlation coefficient than the other adsorption isotherm models. And in the kinetic study, a pseudo-second-order model fit the data best.

Experimental and Molecular Dynamics Simulations for Investigating the Effect of FattyAcid and Its Derivatives on Low Sulfur Diesel Lubricity

In this work,fatty acid and its derivatives were adopted as lubricity additives for low sulfur diesel.Tribological evaluation obtained from the High-Frequency Reciprocating Rig(HFRR)apparatus showed that the lubricating performance of the additives increased in the following order:stearic acid>glycol monopalmitate>stearyl alcohol>ethyl palmitate>cetyl ethyl ether.The adsorption behavior of the additives on Fe(110)surface and Fe2O3(001)surface was investigated by molecular dynamics(MD)simulations to verify their lubricity performance.The results suggested that adsorption energies of the additives on Fe(110)surface are determined by the van der Waals forces,while adsorptions on Fe2O3(001)surface are significantly attributed to the electrostatic attractive forces.Higher values of adsorption energy of the additives on Fe2O3(001)surface indicate that the additive has more efficient lubricity enhancing properties.

Regulation of isobutane/1-butene adsorption behaviors on the acidic ionic liquids-functionalized MCM-22 zeolite

The adsorption ratio of isobutane/1-butene on the catalyst surface is one of the most important factors for the C4 alkylation process. Regulation of isobutane/1-butene adsorption ratio on the zeolite-supported acid catalyst is a big challenge for catalyst preparation. To regulate the isobutane/1-butene adsorption ratio, four types of ionic liquid （i.e., IL） with different alkyl chain lengths and different acid group numbers were synthesized and were subsequently immobilized onto the MCM-22 zeolite. The as-synthesized IL-immobilized MCM-22 （i.e., MCM-22-IL） was characterized by FT1R, TGA, BET, XPS and XRD, and their adsorption capacities and adsorption molar ratios of isobutane to l-butene （I/O） were investigated to correlate with surface features of MCM-22-IL Results showed that the immobilization of ILs led to a decrease of specific surface area and pore volume. But the surface density of acid groups was increased and the adsorption molar ratio of isobutane/1-butene （I/O） was significantly im- proved by the immobilization of ionic liquids. The adsorption molar ratio of I/O is substantially improved from 0.75 to above 0.9 at 300 kPa upon immobilizing ILs. Although the alkyl chain length oflLs was found to have little effect on the adsorption molar ratio of I/O, the increase of acid group numbers led to a dramatic decrease in the adsorption I/O ratio. The results illustrated that immobilizing ionic liquids is an effective way to modify the textural, chemical and morphological properties of MCM-22. Accordingly, the immobilization of ionic liquids provides a novel and a feasible way to regulate the adsorption I/O ratio on an adsorbent or a solid catalyst.

Ru surface density effect on ammonia synthesis activity and hydrogen poisoning of ceria-supported Ru catalysts

Evaluating the effect of metal surface density on catalytic performance is critical for designing high-activity metal-based catalysts.In this study,a series of ceria(CeCO_(2))-supported Ru catalysts(Ru/CeCO_(2))were prepared to analyze the effect of Ru surface density on the catalytic performance of Ru/CeCO_(2) for ammonia synthesis.For the Ru/CeCO_(2) catalysts with Ru surface densities lower than 0.68 Ru nm^(-2),the Ru layers were in close contact with CeCO_(2),and electrons were transferred directly from the CeCO_(2) defect sites to the Ru species.In such cases,the adsorption of hydrogen species on the Ru sites in the vicinity of 0 atoms was high,leading to a high ammonia synthesis activity and strong hydrogen poisoning.In contrast,the preferential aggregation of Ru species into large particles on top of the Ru overlayer resulted in the coexistence of Ru clusters and particles,for catalysts with a Ru surface density higher than 1.4 Ru nm^(-2),for which Ru particles were isolated from the direct electronic influence of CeCO_(2).Consequently,the Ru-Ceth interactions were weak,and hydrogen poisoning can be significantly alleviated.Overall,electron transfer and hydrogen adsorption synergistically affected the synthesis of ammonia over Ru/CeCO_(2) catalysts,and catalyst samples with a Ru surface density lower than 0.31 Ru nm^(-2) or exactly 2.1 Ru nm^(-2) exhibited high catalytic activity for ammonia synthesis.