Adsorption Of Isopropanol Research Articles

Absorption of Isopropanol on Surface of Defect Silicene

In this work, we investigate the defect structure of Silicene with a vancacy and the adsorption mechanism of isopropanol on the surface of defected Silicene by employing the Density Functional Theory method. The adsorption profile was determined based on van der Waals functional optPBE-vdW and the charge transfer between isopropanol and silicene this system was also calculated by Bader charge analysis method. In the defected Silicene, Si vacancy preferably forms on the lower layer of the bulking structure. As a Si vacancy is introduced, Silicene exhibits a metallic behavior with zero bandgap. Due to the losing electron of defected Silicene, isopropanol is adsorbed on the surface with the most favourable adsorption configuration in which oxygen atom towards the surface of Silicene. Isopropanol adsorption opens a tunnelling gap of defected Silicence, resulting in the mili-gap characteristics of the adsorbed Silicene system. The adsorption profile of this volatile organic compound on defected Silicene implies the physics adsorption characteristics. The adsorption energy for isopropanol was found to be -0.40 eV. In addition, the charge transfer of 0.24 electron was obtained

Modulation of Lewis acidic-basic sites for efficient photocatalytic H2O2 production over potassium intercalated tri-s-triazine materials

Photocatalytic H2O2 production (PHOP) on graphitic carbon nitride (GCN) at neutral pHs is limited by the sluggish oxidation of sacrificial alcohols and insufficient protons. In our work, the PHOP over a series of K intercalated triazine (KTCN) or tri-s-triazine units (KTTCN) reached 11–32 folds of GCN in the presence of only 0.5 vol% isopropanol, and a positive correlation between the H2O2 production and the K contents was found. The critical role of K was revealed as that K intercalation creates Lewis acidic sites for isopropanol adsorption and strengthens Lewis basic sites for hydrogen abstraction and proton release. The improved alcohol oxidation and enhanced O2 chemisorption synergistically result in dramatically accelerated PHOP over KTTCN. The findings provide the understanding of the preliminary active site dependent PHOP mechanism and bring insights for design of carbon nitride polymers with desirable photocatalytic performance.

Improved H2O2 photogeneration by KOH-doped g-C3N4 under visible light irradiation due to synergistic effect of N defects and K modification

KOH-doped graphitic carbon nitride (g-C3N4) prepared by thermal copolymerization in the presence of KOH was used for photogeneration of H2O2 under visible light irradiation. The H2O2 yield of the KOH-doped g-C3N4 photocatalyst with isopropanol (IPA) as a scavenger was 704 μM·g−1g-C3N4·h−1, twelve times that of unmodified g-C3N4. The total H2O2 output with IPA as a scavenger increased to 86.08 mM after 60 h. The photogeneration of H2O2 with g-C3N4 occurred as two single-electron reactions in which oxygen was reduced to the superoxide radical by one photogenerated electron and further reduced to H2O2 by reacting with another electron and two protons released by oxidization of IPA by holes. KOH doping had a synergistic effect owing to the strong electron-withdrawing ability of N defects caused by N vacancies and cyano groups, and enhanced electron transport due to K bridges between the C3N4 layers. These effects significantly enhanced the H2O2 photogeneration performance of g-C3N4 by improving the quantum efficiency, narrowing the band gap, strengthening IPA adsorption on g-C3N4, and lowering the energy barrier of the oxygen reduction reaction. This work provides an attractive and promising strategy for green H2O2 production.

Enthalpy of isopropanol adsorption on zeolite

Abstract The enthalpy of isopropanol adsorption on ZSM-5 (Zeolite Socony Mobil Framework Type MFI) was determined by the static adsorption method at the temperature range from 20°C to 100°C. Langmuir and Huttig models of equilibrium adsorption have been used to calculate the enthalpy of isopropanol adsorption at these conditions. Adsorption isotherms determined by the flow method at 20°C and 30°C have been also used in the calculations. The obtained values of isopropanol adsorption enthalpy were compared with the values of isopropanol evaporation enthalpy and with the results obtained from isopropanol and water desorption measurements with thermogravimetry and differential scanning calorimetry methods.

Surface Tension Measurement of Water Surface Under IPA Vapor and the Impact of Its Concentration Dependence on the Marangoni Convection in Wafer Drying Process

As higher integration of semiconductor devices has progressed recently, mechano-chemical polishing process is playing a very important role. At the same time, cleaning and drying technologies after the polishing process have been more and more important in order to ensure the surface cleanliness of the wafer products. As a drying process after the cleaning, there is a method of supplying pure water and IPA (Iso-Propyl Alcohol) vapor simultaneously to the surface of the water meniscus region on a rotating wafer (which is called Rotagoni drying method). This technique causes a surface tension difference on the liquid surface and then gives rise to the convection by the Marangoni effect, which is thought to efficiently remove impure particles on the wafer surface. In this method, IPA vapor impinges on the vicinity of the liquid meniscus on the wafer. It is very difficult to measure the surface tension of the liquid surface in that part in situ, and the details about the convection are not well understood. As this technique further advances in near future in order to remove ultra-fine foreign particles on the wafer surface more efficiently, observation and understanding of the Marangoni convection in the meniscus region are necessary for the future progress of the technique. In this study, in order to consider the actual situation of the drying process, not only the measurement of the surface tension of the droplet of the IPA aqueous solution, but also the measurement by exposing pure water droplet to various concentrations of the IPA vapor were performed, and the relationship between the concentration of IPA vapor and the surface tension of the droplet was investigated. The latter situation is much closer to actual drying situation. Specifically, in measurements, a small pure water droplet was placed in a glass container, and the container was filled with a constant concentration of IPA vapor. At the time when it was judged that the IPA adsorption to the liquid surface had reached equilibrium by confirming that the shape of the droplet became unchanged, the image of the droplet shape was taken from the side of the container with digital camera. It is known that the static shape of a droplet which is flattened under the influence of gravity can be analytically expressed by a mathematical equation in consideration of surface tension and mechanical equilibrium. In this study, the surface tension was deduced by assuming that a uniform concentration of IPA and a uniform surface tension over the whole droplet surface. In another project of the authors’ group, physical simulation using a two-dimensional PDMS flow channel was performed to reproduce a situation of impinging IPA vapor to the meniscus region, and PIV (Particle Image Velocimetry) method was applied to obtain the flow velocity of the Marangoni convection. The measurement of IPA concentration on water surface during the actual drying process is very difficult, and moreover, the in-situ measurement of surface tension is almost impossible. From the data of surface tension as a function of IPA concentration and the measured velocity data with a simple analytical flow model, the estimation of surface tension and IPA concentration on the droplet surface will be discussed. END Figure 1

Functionalization of porous siliceous materials, Part 2: Surface characterization by inverse gas chromatography

Surface modification of porous glass beads by ethanol-based 3-mercaptopropyltrimethoxysilane (MPTMS) grafting solutions is directly evidenced by nitrogen adsorption, elemental analysis, thermogravimetry, infrared and 29Si CP MAS NMR spectroscopy. Furthermore, the energetic characterization of the surface is essential to understand comprehensively the physico-chemical interactions between the pristine and MPTMS-modified surface and its gas/liquid-phase environment. In this study, inverse gas chromatography (IGC) is used to characterize the surface properties of porous glass (PG). By means of IGC at infinite dilution (IGC-ID), the dispersive component of the surface energy (γsd), the enthalpy and entropy of adsorption of C6-C10 hydrocarbon probes were determined at temperatures between 30 and 120 °C. The specific component of the surface energy (γssp) at the temperature of 120 °C has been obtained via the Van Oss theory and a least-squares procedure evaluating the IGC data of 8 polar probe molecules collectively. After surface silylation, the total surface energy (γst) decreased from 402 to 255 mJ/m² indicating both a reduced wettability and an increased hydrophobicity of the MPTMS-modified PG. Moreover, the acidity/basicity parameters according to the Van Oss and the Gutmann approach indicated that the acidity of the PG surface decreases by MPTMS grafting.Using n-octane and isopropanol probes, IGC at finite concentration (IGC-FC) was applied to obtain their adsorption isotherms and subsequently the BET specific surface areas. In addition, the surface heterogeneity of the studied PGs was also computed. The energy distribution functions of adsorption sites were monomodal (peak maximum at about 22 kJ/mol) for the n-octane probe, while isopropanol revealed a bimodal distribution function (maxima at about 18 and 25 kJ/mol) on both pristine and MPTMS-modified PG. Furthermore, the proportion of high energy sites (apparently assigned to SiOH groups) has been reduced by surface modification from 65% to only 35% despite a high surface coverage of ˜10 MPTMS species/nm2. These findings are in agreement with the results of 29Si CP MAS NMR measurements and are supported by DFT calculations on the adsorption of isopropanol and n-octane on the surface of a silica cluster model.

Highly Effective Activated Carbons from Turkish–Kozlu Bituminous Coal by Physical and KOH Activation and Sorption Studies with Organic Vapors

Abstract Activated carbons were produced from coal by activations applying physical and chemical (with KOH) treatments for adsorption of selected organic vapors. Physical activations were carried out at 400–900°C under N2/CO2 flow. The effects of different variables such as carbonization temperature and flow rate on the final porous texture were investigated. Chemical activation gave more effective results in terms of both porosity development and adsorption capacity. Pore characterization of carbon samples was evaluated with the observation of N2 adsorption-desorption isotherms at 77 K. The adsorption of isopropyl alcohol, acetone and ethyl alcohol on the coal derived activated carbons were determined by a volumetric technique at room temperature. The highest surface area was obtained as 1904 m2/g by KOH treatment at 800°C. The adsorption isotherm data of the selected organic vapors on carbon samples were compared with the BET, Langmuir, Freundlich, Dubinin-Radushkevich, Dubinin-Astakhov, Harkins-Jura, Henderson, Halsey and Smith adsorption models. Adsorption capacities of organic vapors for carbon samples were related with the development of surface area. Among the four chemically activated carbons produced K1_K_600, K1_K_700 and K1_K_800 showed better isopropyl alcohol and acetone adsorption than the commercial activated carbon. K1_K_700 and K1_K_800 samples showed better ethyl alcohol adsorption. Isopropyl alcohol, acetone and ethyl alcohol adsorption capacities of the obtained sample that had the maximum surface area were determined as 39.7, 44 and 43.5 %, respectively. Results indicate that activated carbons prepared with KOH at 600–800°C could be effectively used for the adsorption of organic vapors.

Adsorption of Isopropyl Alcohol (IPA) in Water Using Activated Bentonite

It has been done separation isopropyl alcohol (IPA) in water using activated bentonite as adsorbent. Preparation of activated bentonite is done using H2SO4 1 M. Characterization of adsorbent includes structural analysis with XRD, surface area and pore size using the BET method. The adsorption test is carried out in a batch system with variations in stirring time, adsorbent mass, pH and temperature. Analysis of the amount of IPA adsorbed is determined by a picnometer. The results of the adsorption test showed that the adsorption capacity optimum of IPA by activated bentonite was 116.62 mg/g at optimum conditions, i.e. 40 minutes stirring time, 1 g of active bentonite mass, at 30 °C and acidity level 7. Model of isotherm adsorption of IPA in activated bentonite are isotherm Langmuir model with corelation coefficient (R2) of 0,9283. The thermodynamic parameters (ΔH°, ΔS° and ΔG°) are 189.37 J·mol−1,−1.08 J·mol−1·K−1 and 132.63 J·mol−1respectively.

Solvent effects on the retention mechanisms of an amylose-based sorbent

The mobile phase, when used in combination with a polysaccharide-based sorbent, often contains hydrocarbons with polar modifiers. Studies have investigated the effect of solvent on the recognition mechanism of polysaccharide-based sorbents, but it remains unclear how these modifier molecules affect solute retention behavior. This study used an amylose 3,5-dichlorophenylcarbamate–based sorbent to systematically investigate the retention behavior of various solutes as a function of the concentration of four polar modifiers: ethanol, isopropanol, methyl tert-butyl ether, and acetone. The thermodynamic properties of adsorption for the four modifiers were thoroughly investigated using retention factor data, van’t Hoff plots, and adsorption isotherms of the modifier molecules. The adsorption data of acetone and isopropanol followed the Langmuir isotherm, whereas the bi-Langmuir isotherm more accurately fit the ethanol data. For methyl tert-butyl ether, the Brunauer–Emmett–Teller adsorption isotherm indicated multilayer adsorption with a low saturation capacity of the first adsorption layer. A multivalent retention model interpreted slopes of the plots of the logarithm of the retention factor versus the logarithm of the modifier concentration. Because the molecular polarity of acetone is stronger than that of methyl tert-butyl ether, the limiting absolute slope values of tetrahydrofuran at a very high acetone modifier concentration were smaller than that when methyl tert-butyl ether was used as the polar modifier. The higher absolute value of the slope for tert-butanol suggested the potential of CO groups of acetone molecules to form bifurcated H bonds on a tert-butanol molecule. When alcohol was employed as the polar modifier, the results suggested that the effect of isopropanol self-association on the retention factor was stronger than the effects of solute–IPA complexation and isopropanol adsorption. For alcohol modifiers, U-shaped retention curves were obtained for all aromatic solutes. When acetone or methyl tert-butyl ether was used, the absence of a U-shaped curve indicated the weak polarity of those modifiers.

Adsorption dynamics of isopropanol in structured fixed bed with microfibrous ZSM-5 zeolite structured composite

Abstract The micro-fibrous ZSM-5 zeolite structured composite (ZSM-5/PSSF), prepared by combining wet lay-up paper-making with sintering technique followed by secondary growth process, was applied in isopropanol (IPA) adsorption dynamics in structured fixed bed. ZSM/PSSF was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) as well as N2 adsorption–desorption isotherm. Adsorption dynamics of isopropanol in structured fixed bed indicated a significant mass transfer enhancement. Bed pressure drop of structured packed bed decreased drastically attributed to excellent permeation nature of 3D network structure in paper-like stainless steel fiber (PSSF). Length of unused bed (LUB) reduced when ZSM-5/PSSF was packed in proper proportions. Breakthrough curves could be well fitted by both Yoon–Nelson and Bed depth service time (BDST) models, rate constant k′ and ka also confirmed enhancement of mass transfer. In conclusion, excellent mass transfer, low bed pressure drop and high utilization of bed made great contributions in improving adsorption performance of IPA in structured fixed bed.

119Sn MAS NMR Study of the Interaction of Probe Molecules with Sn-BEA: The Origin of Penta- and Hexacoordinated Tin Formation

119Sn CPMG MAS NMR was applied to study the adsorption of acetonitrile, methanol, isopropyl alcohol, isobutyl alcohol, and water over Sn-BEA enriched with 119Sn isotope. Two signals observed at ca. −422 and −443 ppm over dehydrated samples were attributed to tetracoordinated framework tin sites with strong and weak Lewis acidity, respectively. The adsorption of acetonitrile and methanol resulted in the observation of pentacoordinated tin species, due to the formation of 1:1 adsorption complexes over both Sn sites. Water adsorption led first to formation of pentacoordinated tin species, which were further converted into hexacoordinated species at longer reaction times. The latter transformation was found to be kinetically limited and was attributed to chemical interaction of tin sites with water, such as hydrolysis of Si–O–Sn bonds. The adsorption of isopropyl alcohol and isobutyl alcohol was accompanied by the formation of pentacoordinated Sn species in the case of weak sites and hexacoordinated Sn over s...

Desorption of isopropyl alcohol from adsorbent with non-thermal plasma

ABSTRACTEffective desorption of isopropyl alcohol (IPA) from adsorbents with non-thermal plasma is developed. In this system, IPA is effectively adsorbed with activated carbon while dielectric barrier discharge is applied to replace the conventional thermal desorption process to achieve good desorption efficiency, making the treatment equipment smaller in size. Various adsorbents including molecular sieves and activated carbon are evaluated for IPA adsorption capacity. The results indicate that BAC has the highest IPA adsorption capacity (280.31 mg IPA/g) under the operating conditions of room temperature, IPA of 400 ppm, and residence time of 0.283 s among 5 adsorbents tested. For the plasma desorption process, the IPA selectivity of 89% is achieved with BAC as N2 is used as desorbing gas. In addition, as air or O2 is used as desorbing gas, the IPA desorption concentration is reduced, because air and O2 plasmas generate active species to oxidize IPA to form acetone, CO2, and even CO. Furthermore, the results of the durability test indicate that the amount of IPA desorbed increases with increasing desorption times and plasma desorption process has a higher energy efficiency if compared with thermal desorption. Overall, this study indicates that non-thermal plasma is a viable process for removing VOCs to regenerate adsorbent.

Heterogeneous Interaction of Isopropanol with Natural Gobi Dust.

The adsorption of isopropanol on Gobi dust was investigated in the temperature (T) and relative humidity (RH) ranges of 273-348 K and <0.01-70%, respectively, using zero air as bath gas. The kinetic measurements were performed using a novel experimental setup combining Fourier-Transform InfraRed spectroscopy (FTIR) and selected-ion flow-tube mass spectrometry (SIFT-MS) for gas-phase monitoring. The initial uptake coefficient, γ0, of isopropanol was measured as a function of several parameters (concentration, temperature, relative humidity, dust mass). γ0 was found independent of temperature while it was inversely dependent on relative humidity according to the empirical expression: γ0 = 5.37 × 10-7/(0.77+RH0.6). Furthermore, the adsorption isotherms of isopropanol were determined and the results were simulated with the Langmuir adsorption model to obtain the partitioning constant, KLin, as a function of temperature and relative humidity according to the expressions: KLin = (1.1 ± 0.3) × 10-2 exp [(1764 ± 132)/T] and KLin = 15.75/(3.21+RH1.77). Beside the kinetics, a detailed product study was conducted under UV irradiation conditions (350-420 nm) in a photochemical reactor. Acetone, formaldehyde, acetic acid, acetaldehyde, carbon dioxide, and water were identified as gas-phase products. Besides, the surface products were extracted and analyzed employing HPLC; Hydroxyacetone, formaldehyde, acetaldehyde, acetone, and methylglyoxal were identified as surface products while the formation of several other compounds were observed but were not identified. Moreover, the photoactivation of the surface was verified employing diffuse reflectance infrared fourier transform spectroscopy (DRIFTs).

Sorbent track: Quantitative monitoring of adsorbed VOCs under in-situ plasma exposure.

Sorbent-TRACK is a new device developed to monitor adsorption and surface oxidation of pollutants under direct plasma exposure. It is based on direct transmitted Fourier Transformed Infrared (FTIR) spectroscopy. A pyrex reactor under controlled gas pressure and composition is inserted on the infrared beam of a commercially available Nicolet 5700 FTIR spectrometer. A substrate holder is located on the optical path of the infrared beam. A thin pellet of a dedicated catalyst (CeO2 in the present work) is inserted in a substrate holder and can be exposed to direct plasma treatment using a Dielectric Barrier Discharge. The time resolution of Sorbent-TRACK is limited by the time resolution of the Nicolet 5700 FTIR spectrometer and close to 30 s. The dynamic of the adsorption and plasma oxidation of acetone and isopropanol on CeO2 are studied and intermediates are monitored. Performances and sensitivity of Sorbent-TRACK are reported Adsorption and oxidation of acetone leads to production of adsorbed isobutene and acetic acid, where oxidation of isopropanol gives mainly to adsorbed acetone, mesityl oxide and acetate. An increase of the plasma power leads to an increase of the isopropanol and acetone oxidation rate and a related increase of the production of adsorbed intermediates.

Elucidation of adsorption mechanisms of solvent molecules with distinct functional groups on amylose tris(3,5-dimethylphenylcarbamate)-based sorbent

Although polysaccharide derivative-based sorbents have been widely used for chiral separation, for a long time it remained unclear how these CSPs interact with the molecules associated with different functional groups. In this study, six molecules were chosen for retention behavior studies: acetone (AC), tetrahydrofuran (THF), methanol (MET), isopropanol (IPA), tert-butanol (TBA), and benzene (BZN). An immobilized amylose carbamate stationary phase, amylose tris(3,5-dimethylphenylcarbamate)-based sorbent, or Chiralpak IA, was used. Van’t Hoff plots of ln k versus 1/T showed that alcohol molecules may simultaneously form two H-bonds with the IA sorbent. The results of density functional theory simulations and IR spectra support this inference showing that alcohol may bind with amide groups in three possible configurations. Frontal tests of AC and IPA were performed to estimate adsorbed solute concentration. Langmuir isotherm for IPA adsorption and mass action model for IPA self-aggregation were used for analyzing the IPA frontal results. Average IPA aggregation numbers range from 1.4 to 2.3. More than fifty percent of IPA molecules were found to be in aggregate form. From the frontal test results, thermodynamic properties of the adsorptions were determined. Retention behaviors of the five solutes as a function of IPA concentration were investigated. The absolute values B of the slopes from plots of the logarithms of the retention factor versus the logarithms of the IPA concentration increase in the order THF<AC<TBA<MET. U-shaped retention curves were observed for BZN, indicating that π-interactions of BZN aromatic group with the IA sorbent may involve both electrostatic and hydrophobic interactions. For THF, the slightly concave upward retention curves also suggested potential hydrophobic interactions between THF and IA. A monovalent retention model was used to estimate equilibrium constants (KSL-A) of solute-IPA complexation. The retention factors of the solutes with larger KSL-A values increase more rapidly with a decrease in the IPA concentration. Hence, a combination of the thermodynamic analysis and retention model has been shown to be reliable approach for elucidating the adsorption mechanisms of monovalent molecule containing different functional groups.

Isopropyl alcohol vapour removal from diluted gaseous stream by adsorption: Experimental results and dynamic model

The gas phase adsorption of isopropyl alcohol (IPA) onto a commercial activated carbon at 30°C was investigated under different operating conditions. Fixed-bed experiments were performed to obtain equilibrium and kinetic data for IPA adsorption. The equilibrium data were fitted by means of the Langmuir equation and isotherm parameters were determined. A dynamic, isothermal, dilute solution adsorption model, based on the linear driving force (LDF) approximation, was developed to describe the kinetic adsorption behavior. A very good agreement between experimental and model results was found when a LDF mass-transfer-rate coefficient dependent on the gas concentration was used.

Adsorption of acetone and isopropanol on organic acid modified activated carbons

Commercial activated carbon (AC) was modified using formic acid, oxalic acid, and sulfamic acid separately. The effects of the modification on the physicochemical properties of ACs were evaluated using specific surface area and pore distribution, scanning electron microscope, and Fourier transform infrared spectroscopy. After the modification, (i) the BET specific surface area and total pore volume of ACs decreased, (ii) uneven etching trace and white crystal particles were observed on the surface of AC, and (iii) more oxygen-containing functional groups such as OH, CO, CO, and SO were formed on the surface. The effects of the modifications on the adsorption behavior of acetone and isopropanol on ACs at different inlet concentrations were studied from adsorption equilibrium, kinetics, and energy point of view. The results show that the equilibrium adsorption capacity has been greatly improved by the modification of organic acids. The adsorption isotherms of acetone and isopropanol on ACs are well fitted by both Langmuir and Freundlich equations. Characteristic adsorption energy values of acetone and isopropanol slightly increase with increasing of oxygen functional groups on the ACs surface. The adsorption kinetics of acetone and isopropanol on ACs are best described by Bangham kinetics model.

Modifying the catalytic and adsorption properties of metals and oxides

A new approach to interpreting the effect of promoters (inhibitors) of nonmetals and metals added to a host metal (catalyst) is considered. Theoretical calculations are based on a model of an actual two-dimensional electron gas and adsorbate particles. An equation is derived for the isotherm of induced adsorption on metals and semiconductors with respect to small fillings of θ ~ 0.1–0.15. The applicability of this equation is verified experimentally for metals (Ag, Pd, Cu, Fe, and Ni), graphitized ash, and semiconductor oxides Ta2O5, ZnO, and NiО. The applicability of the theoretical model of promotion is verified by the hydrogenation reaction of CO on ultradispersed nickel powder. The use of plasmachemical surface treatments of metals and oxides, accompanied by an increase in activity and variation in selectivity, are investigated based on the dehydrocyclization reactions of n-hexane and the dehydrogenation and dehydration of alcohols. It is established that such treatments for metals (Pt, Cu, Ni, and Cо) raise their activity due to the growth of the number of active centers upon an increase in the activation energy. Applying XPES and XRD methods to metallic catalysts, it is shown that the rise in activity is associated with a change in their surface states (variation in the structural characteristics of metal particles and localization of certain forms of carbon in catalytically active centers). It is shown that plasmachemical treatments also alter their surface composition, surface activity, and raise their activity when used with complex phosphate oxides of the NASICON type. It is shown by the example of conversion of butanol-2 that abrupt variations in selectivity (prevalence of dehydration over dehydrogenation and vice versa) occur, depending on the type of plasma. It is concluded that plasmachemical treatments of metals and ZnO and NiO alter the isosteric heats and entropies of adsorption of isopropanol.

Fabrication of novel porous carbon membrane/sintered metal fibers composite for isopropanol adsorption

Novel porous thin-sheet carbon membrane/sintered metal steel fibers (SMFs) composites were developed by the dipping and carbonization process. These novel carbon membrane materials have been characterized by a series of techniques including thermal gravimetric analyses (TGA), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and N2 adsorption–desorption method. Adsorption breakthrough curves of isopropanol in the structured fixed bed filled with both activated carbons in the inlet of bed and carbon membrane/SMFs composites in the outlet of bed were investigated, comparing with that in fixed bed containing only activated carbons with the same bed height. The experimental results indicated that the carbon membranes with different thickness from 748.1nm to 1.27μm were successfully fabricated on the surface of SMFs support. The length of unused bed (LUB) theory was also employed to study the breakthrough curves. The porous carbon membrane/SMFs composites filled in fixed be show exhibited excellent bed utilization, demonstrating by a lowest LUB value (1.17cm). The porous carbon membrane/SMFs composites as high efficiency adsorbents can offer a much higher mass transfer efficiency, contacting efficiency as well as adsorption rate.

Effects of water on the hydrogenation of acetone over Ni/MgAlO catalysts

The effect of water on the hydrogenation of acetone to isopropanol (IPA) on the Ni/MgAlO catalyst was studied. It was found that small amount of water added in the acetone promoted the conversion of acetone to IPA, while more H2O added (>5%) significantly decreased the conversion of acetone. Microcalorimetric adsorption results showed that the presence of small amount of pre-adsorbed water (4% coverage) enhanced the adsorption of acetone while inhibited the adsorption of IPA on Ni, which might be the important reasons for the promotion effect of some water on the hydrogenation of acetone to IPA. On the other hand, the heats for the adsorption of H2, acetone and IPA on the Ni/MgAlO were significantly decreased when more water was pre-adsorbed, which might explain the inhibition effect of more water on the hydrogenation of acetone. The results of infrared spectroscopy revealed that the presence of water suppressed the dehydrogenation of adsorbed IPA to acetone and the formation of enolate and mesityl oxide species from adsorbed acetone, which might be the other reasons for the positive effect of water on the hydrogenation of acetone to IPA.