In the Journal of the American Chemical Society, Stylianou et al have reported on the investigation of the structural transformation of a Zn-based flexible
Publication Highlights from 2013!
At the end of this, the first full year of our new blog, we have decided to take a look back at some of the publication highlights from 2013.
Our collection of papers that include data measured using Hiden Isochema instruments continues to grow and now exceeds 500, with articles published in over 160 different peer-reviewed journals; this fact nicely illustrates the breadth of application areas that are served by our gas and vapor sorption instrumentation.
The highlights from 2013, as reported below, include the following topics:
- Hydrocarbon diffusion in polymers
- Mass transport behaviour in hierarchically-structured zeolites
- Methane adsorption by shales
- Hydrogen sorption by metal hydrides and nanoporous materials
- Carbon capture using supported ionic liquid membranes
- Carbon dioxide adsorption by nanoporous materials
We hope that this selection of papers will give existing customers an interesting insight into the different ways in which our instruments can be used but also that it will provide a glimpse into what is possible for those visitors new to Hiden Isochema’s gas and vapor sorption analysis tools.
If you would like to discuss the possibilities with us, please do not hesitate to contact us. Otherwise, we hope you enjoy the selection of studies outlined below. If you wish, you can just skip straight to the reference list.
We begin with a couple of examples of vapor sorption work, one of which we covered briefly in our Autumn 2013 newsletter:
Professor Jingdai Wang from the Department of Chemical Engineering, Zheijang University, China, and his co-workers studied the diffusion of isopentane (i-C5H12), 1-hexane (C6H14) and cyclohexane (C6H12) in polyethylene particles using an IGA-003 . By applying a kinetic desorption method Professor Wang and his team were able to extract effective diffusion coefficients for the different hydrocarbon species in the material as a function of parameters such as the particle size and the measurement temperature. This paper provides an excellent example of the use of the IGA to study diffusion phenomena in polymeric materials.
Also on the topic of vapor diffusion, but for a rather different application, Professor Javier Pérez-Ramírez from the Institute for Chemical and Bioengineering, ETH Zurich, Switzerland, and his co-workers studied the diffusion rate of 2,2-dimethylbutane in a hierarchically-structured ZSM-5 zeolite sample using an IGA-002 vapor sorption analyzer. One of the reasons for introducing mesoporosity or macroporosity into microporous zeolites is to enhance their mass transfer properties, which can be limited in microporous solids. A series of kinetic adsorption measurements presented in this paper show the dramatic enhancement in the mass transfer properties of these materials due to the introduction of a hierarchical pore structure. 2,2-dimethylbutane is a branched alkane with a kinetic diameter of 0.61 nm, which is very close to the pore diameter of ZSM-5, and so its diffusion in this material can be expected to be kinetically restricted. What this study demonstrates particularly well is, firstly, the quantitative improvement in the diffusion rates due to the modification of the porosity of the ZSM-5, but also the ability of the gravimetric technique, as implemented in our IGA series, to provide such kinetic information.
The study above by Professor Pérez-Ramírez and his co-workers was covered briefly in our Autumn 2013 newsletter. Another study we mentioned, covered also in an earlier blog item, is the methane adsorption by shale study published in Energy & Fuels earlier this year . We’ve probably said enough about this work already (see our previous blog item on methane adsorption by shale) but we wanted to nevertheless include it in our list of 2013 highlights!
Next up, we have a series of papers that take advantage of the high accuracy and high pressure operation of our IMI series of manometric gas sorption analyzers, and it is gratifying indeed for us to see more high quality data appearing in the literature from these instruments. In each case, the instrument of choice was the HTP1-V, which is the predecessor of our current IMI-HTP.
Dr David Book and his co-workers in the School of Metallurgy and Materials at the University of Birmingham, UK, studied hydrogen uptake by Ti-V-Mn alloys . The study uses a range of techniques, including scanning electron microscopy (SEM) and X-ray powder diffraction (XRD), but features some particularly nice hydrogen absorption and desorption isotherms measured up to 120 bar (12.0 MPa) at near ambient temperatures, together with van ‘t Hoff plots for two samples of slightly differing stoichiometry. The isotherms, in particular, demonstrate the dramatic effect that relatively small changes in stoichiometry can have on the hydrogen absorption and desorption properties of multicomponent metal hydrides.
Our other examples feature hydrogen adsorption, rather than absorption. Firstly, we have a report by Professor Sanping Chen and his co-workers in the College of Chemistry and Materials Science, Northwest University, China, and collaborators at Shangluo University, China, which examined the hydrogen adsorption capacity of an unusual heterometallic MOF . The material includes both Cr and Cu contained within two kinds of paddlewheel building blocks ([Cu2C4O8] and [CuCrC4O8]), which are formed by four carboxylates that bridge binuclear homometallic copper atoms or heteronuclear copper-chromium atoms. The resultant structure has two distinct cages and shows a significant amount of hydrogen uptake and a high isosteric enthalpy of hydrogen adsorption.
Secondly, we have a study by Dr Tim Mays and his team at the Department of Chemical Engineering, University of Bath, UK, which looks at different methods for calculating the isosteric enthalpy of hydrogen adsorption using variable temperature measurements on the activated carbon, AX-21, and the metal-organic framework, MIL-101. Although careful analysis of different methods for calculating the isosteric enthalpy of adsorption from experimental data is the most important aspect of this work, we particularly like it because it nicely demonstrates the use of our IMI series for hydrogen adsorption measurements on nanoporous materials at variable low temperatures.
We now move on to an interesting study by Professor Lee Brammer of the Department of Chemistry, University of Sheffield, UK, and Dr Ashleigh Fletcher of the Department of Chemical and Process Engineering, University of Strathclyde, UK, and their collaborators, which features a one-dimensional coordination polymer that forms a non-porous crystal. Despite its lack of permanent porosity, the material can undergo multiple reversible single-crystal-to-single-crystal transformations via a solid-vapor reaction with small alcohol molecules, such as methanol, ethanol and isopropanol . The structural changes induced by the presence of these alcohols were followed using both laboratory and synchrotron X-ray diffraction; however, this crystallographic work was complemented by the measurement of the uptake of CO2 by the host compound [Ag4(O2C(CF2)2CF3)4(TMP)3]n (TMP = 2,3,5,6-tetramethylpyrazine) using an IGA gas sorption analyzer. Three steps were seen in the sorption isotherm, which was measured up to 10 bar (1.0 MPa) at 295 K. Although the first step was small and was indicative of adsorption on the external surface of the particles, the two larger steps at approximately 2.6 bar (260 kPa) and 3.9 bar (390 kPa), which were accompanied by some hysteresis, are most likely due to the structural rearrangement that also accompanies the sorption of small alcohol molecules. This work clearly demonstrates the usefulness of gas sorption measurements in supporting the study of novel solid state phenomena.
In a more applied study, a team led by Dr George Romanos from the Division of Physical Chemistry, NCSR “Demokritos”, Athens, Greece, together with researchers from The Netherlands and Germany, investigated the use of room temperature ionic liquids (RTILs) in nanoporous ceramic membranes for CO2/N2 separation . A variety of characterization techniques were used in this work on Supported Ionic Liquid Membranes (SILMs) but, most crucially, an IGA-001 was used to determine the solubility of both CO2 and N2 in the RTILs up to 20 bar (2.0 MPa); as a result, Dr Romanos and his team were able to calculate both Henry’s Law constants and CO2/N2selectivities . They also measured kinetic data to determine the diffusivities of both gases in the bulk RTILs. Interestingly, due to the narrow pores of the support used in this study, which introduces nanoconfinement effects, the predicted pure gas permeabilities and CO2/N2 selectivities from the bulk measurements differed dramatically from the results of permeability and selectivity measurements on the membranes themselves, which were made using a Wicke−Kallenbach cell. This clearly demonstrates the importance of considering the effects of nanoconfinement on the performance of such membranes.
We conclude our round-up with a series of papers on carbon dioxide adsorption by nanoporous materials, which is currently a hot topic due to the urgent need to develop more efficient carbon capture and storage (CCS) technology for the reduction of harmful greenhouse gas emissions.
We start with some work by the group of Dr Krista Walton in the School of Chemical and Biomolecular Engineering at Georgia Institute of Technology, US, on the adsorption of CO2, CH4 and H2O by a water resistant MOF . This paper addresses a crucial aspect of the use of MOFs, and nanoporous adsorbents, in general, for the capture of carbon dioxide, which is the response of the material to the presence of the water vapor that is frequently present in real gas streams. UiO-66, the metal-organic framework examined in this study, is particularly robust, but it is also fairly hydrophilic; however, a functionalized form of the material, designed to introduce hydrophobicity, is shown to adsorb considerably less water at 298 K than the undecorated form, whilst maintaining the high stability of pure UiO-66. Furthermore, the CO2/CH4 selectivity of the functionalized material for an equimolar mixture at higher pressures (10-20 bar, 1.0-2.0 MPa) is higher than that of the parent compound. This material is therefore of interest for adsorptive carbon dioxide capture from natural gas. The study, in general, also provides an excellent demonstration of the use of our IGA series gas and vapor sorption analyzers to characterize novel nanoporous materials for gas separation and purification applications.
We then travel north of the border to look at some interesting higher temperature work led by Professor Maria Iliuta from the Department of Chemical Engineering, University of Laval, Canada. In this case, an IGA-003 was used to study the cyclic CO2 adsorption-regeneration process for a CaO-based material for CCS technology . The adsorption measurements were carried out with a 15 vol.% CO2 in Ar mixture at temperatures of 600°C, 650°C and 700°C, while the regeneration was performed at 750°C in pure Ar. This is a very interesting demonstration of the use of an IGA to perform high temperature adsorption and desorption measurements, because adsorption is often studied under conditions much closer to ambient. This study thus illustrates the flexibility of the IGA series.
Finally, we shall finish by mentioning a very nice paper by Professor Sheng Dai of Oak Ridge National Laboratory in the US and the Department of Chemistry, University of Tennessee, Knoxville, and his collaborators, in which they report the development and characterization of carbon membranes for CO2 separation . In this work, Professor Dai and his collaborators from the Department of Chemistry at the East China University of Science and Technology in Shanghai, synthesize N-doped carbonaceous membranes via the thermal treatment of novel porous organic polymers. The membranes were found to exhibit excellent CO2/N2 selectivity, which was attributed to a combination of the effects of strong dipole-quadrupole interactions between CO2 and the polar sites associated with N-doped groups and the presence of narrow microporosity. The crucial role played in this study by the IGA lies in the determination of the equilibrium CO2 and N2 uptakes of the membrane material at near ambient temperatures.
If you would like to discuss any of the above in more detail or would like any further information on our gas and vapor sorption instruments, please do not hesitate to get in touch via our contact form.
And if you are a customer and you have publications that you think we might not be aware of, please send them to us – we would love to hear about them –contact form.
 M. Chen, J. Wang, B. Jiang and Y. Yang (2013) Diffusion measurements of isopentane, 1-hexene, cyclohexane in polyethylene particles by the Intelligent Gravimetric Analyzer, Journal of Applied Polymer Science 127(2), p. 1098-1104
 L. Gueudré, M. Milina, S. Mitchell and J. Pérez-Ramírez (2013) Superior mass transfer properties of technical zeolite bodies with hierarchical porosity, Advanced Functional Materials, DOI: 10.1002/adfm.201203557
 N. Bimbo, J. E. Sharpe, V. P. Ting, A. Noguera-Díaz and T. J. Mays (2013) Isosteric enthalpies for hydrogen adsorbed on nanoporous materials at high pressures, Adsorption, DOI: 10.1007/s10450-013-9575-7
 I. J. Vitórica-Yrezábal, G. M. Espallargas, J. Soleimannejad, A. J. Florence, A. J. Fletcher and L. Brammer (2013) Chemical transformations of a crystalline coordination polymer: a multi-stage solid-vapour reaction manifold, Chemical Science 4, p. 696-708
 A. I. Labropoulos, G. Em. Romanos, E. Kouvelos, P. Falaras, L. Likodimos, M. Francisco, M. C. Kroon, B. Iliev, G. Adamova and T. J. S. Schubert (2013) Alkyl-methylimidazolium tricyanomethanide ionic liquids under extreme confinement onto nanoporous ceramic membranes, Journal of Physical Chemistry C 117, p. 10114-10127
 H. R. Radfarnia and M. C. Iliuta (2013) Limestone acidification using citric acid coupled with two-step calcination for improving the CO2 sorbent activity, Industrial & Engineering Chemistry Research 52, p. 7002-7013
 X. Zhu, C. Tian, S. Chai, K. Nelson, K. S. Han, E. W. Hagaman, G. M. Veith, S. M. Mahurin, H. Liu and S. Dai (2013) New tricks for old molecules: Development and application of porous N-doped, carbonaceous membranes for CO2 separation, Advanced Materials 25(30), p. 4152-4158