Physical Solvent Research Articles

Hydrate-based acidic gases capture for clean methane with new synergic additives

The widespread need for carbon dioxide (CO2) and hydrogen sulfide (H2S) removal from potential gaseous fuel processes associated with upgrading of natural gas, biogas and landfill gas has led to a continuing interest in developing acid gas capture technologies. This work experimentally investigated the hydrate-based acidic gases (CO2 and H2S) capture for clean methane (CH4) fuel from biogas or natural gas with new synergic additives, which comprised physical gas solvent (TMS) and traditional hydrate promoter (TBAB). The results show that, with the synergic additives, the equilibrium hydrate formation pressures were moderated by about 90% relative to pure water, the selectivity of CO2 over CH4 and the selectivity of H2S over CH4 could achieve 18.56 and 11.38, respectively. Compared with TBAB, the synergic additives could improve the hydrate formation rate and the gas storage capacity by 149% and 84%, respectively. Furthermore, the promotion effect could be enhanced when with the help of H2S. It has been shown that CO2 and H2S could be synchronously captured through the hydrate formation process. It will be of importance to the fundamental study of enhancing gas hydrate formation process, and of practical significance for the hydrate-based application industry.

Technical and Economic Assessments of Ionic Liquids for Pre-Combustion CO2 Capture at IGCC Power Plants

This study evaluates the feasibility and cost of ionic liquids (ILs) for precombustion carbon dioxide (CO2) capture at integrated gasification combined cycle power plants. The ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide is selected as a physical solvent for CO2 capture. Using newly developed performance and cost models, our analysis shows that the energy penalty of the IL-based capture system mainly arises from powering various compressors and solvent pumps, and compressors and absorbers are the dominant capital cost components. Using the Integrated Environmental Control Model (IECM) for power plant assessments, the cost of CO2 avoided by the IL-based capture system is estimated to be $62/t CO2 in constant 2011 USD. The preliminary comparisons of performance and cost between IL- and Selexol-based capture systems show that an IL-based capture system could be a viable alternative to current liquid solvent processes.

Performance of a Carbon Dioxide Removal Process Using a Water Scrubber with the Aid of a Water-Film-Forming Apparatus

With tap water as a physical solvent to absorb CO2 from different concentrations of mixed gases (containing CO2 and N2), an apparatus outfitted with a water-film generator was used to enhance the CO2 dissolution rate as well as the contact between the liquid and gas phases. The operational pressure in the absorption tank, induced gas pressure, initial CO2 content, liquid-to-gas ratio, and temperature had a significant effect on the CO2 removal efficiency and its absorption rate in water. On varying the experimental conditions, the CO2 removal ability and absorption rate varied from 22.9 to 90.0% and 4.5 × 10−4–44.4 × 10−4 mol s−1 L−1, respectively. For instance, the removal and absorption rates reached approximately 90.0% and 12.0 × 10−4 mol s−1 L−1, respectively, when the experiment was operated at 10 °C and 0.30 MPa of gas pressure with 35% CO2 inlet gas content and 1.40 liquid-to-gas ratio. Additionally, a statistical tool, the Taguchi method, was applied to evaluate the effects of four parameters thoroughly and systematically. According to the Taguchi analysis results of nine total runs for four independent variables with three levels for each, the two most significant variables for the removal rate were temperature and liquid-to-gas ratio, whereas those for the absorption rate were inlet gas CO2 concentration and gas compressed pressure. These results may provide evidence to aid in the adoption of this method for large-scale CO2 capture from exhaust gases.

CFD Study of Hybrid Membrane Contactors for Absorption and Stripping of Carbon Dioxide

Carbon capture and storage (CCS) has been identified as an essential technology to meet the internationally agreed goal of limiting the temperature increase to 2°C. Compared to traditional gas-liquid contactors, the membrane contactors provide many beneficial features, including the high specific area, independent gas and liquid flows, modular units and easy to include internal heat exchange. The solvent carbon dioxide absorption processes employing membrane contactors is an important technology. Limited by the low partial pressure of carbon dioxide, physical absorption is not a feasible technology for post-combustion flue gas treatment. However, chemical absorption technology is high energy consumption. In this study, an innovative hybrid absorption/stripping membrane contactor (HASMC) for physical solvent carbon capture is proposed. The simultaneous absorption and stripping can enhance the effectiveness of carbon capture. The device can raise the feasibility of applying physical solvent technology to the treatment of gases with low carbon dioxide partial pressure. In this paper, computational fluid dynamics simulation of the concentration profiles and mass fluxes for parallel-flow and cross-flow modules are presented.

Evaluación de métodos de extracción para la obtención del ácido giberélico en semillas germinadas de maíz (Zea mays L.)

El maíz (Zea mays L.) es el segundo cereal de mayor cultivo a nivel mundial el cual es empleado como materia prima en diferentes industrias. Hasta el momento no se han encontrado reportes de la obtención del ácido giberélico (GA3) en esta planta. En el presente trabajo se compararon los métodos de extracción sólido-líquido por lixiviación y la extracción dinámica con disolvente asistida por sonicación (DSASE) para la obtención del GA3 a partir de semillas germinadas de maíz. Los factores trabajados en la extracción por lixiviación fueron el método físico, el solvente y el tiempo, mientras que los parámetros por DSASE fueron el flujo, el solvente y el tiempo. La mayor concentración del GA3 se obtuvo con el método DSASE (30,012 mg/kg), empleando como solvente acetonitrilo-ácido fórmico 5% (80:20, v:v) a un flujo de 0,4 mL/min y un tiempo de extracción de 25,0 min. La identificación y la cuantificación del GA3 se realizó mediante cromatografía líquida de alta eficiencia (HPLC) con detector de arreglo de diodos (DAD). Estos resultados evidenciaron que la DSASE es una alternativa novedosa para la obtención del GA3, dada su alta eficiencia, el bajo consumo de solvente y su simplicidad en la obtención del extracto.

Hydrate-based Capture of Acidic Gases for Clean Fuels with New Synergic Additives

Abstract The widespread need for the removal of carbon dioxide (CO 2 ) and hydrogen sulfide (H 2 S) from process gas streams associated with hydrogen synthesis plants, upgrading of natural gas, landfill gas recovery, and enhanced oil recovery has led to a continuing interest in developing acid gas separation technologies. This work experimental investigated the hydrate formation processes for capturing acidic gases (CO 2 and H 2 S) from mixture gas (biogas and natural gas) with a new synergic additive, which is composed physical gas solvent (TMS) and traditional hydrate promoter (TBAB). Based on the thermodynamic and kinetic studies, the results show that the hydrate formation process with the synergic additives can capture CO 2 and H 2 S synchronously. The synergic additives not only can considerably moderate the equilibrium hydrate formation conditions, but also make high selectivity of CO 2 and H 2 S over CH 4 during the hydrate formation process, and improve the formation rate and gas storage capacity through their excellent promote effect on the solubility and diffusivity of acidic gases. It will be of practical interest in relation to the fundamental study of enhancing gas hydrate formation and of potential importance for the industry application of gas hydrate.

Slippery Liquid-Immobilized Coating Films Using in Situ Oxidation-Reduction Reactions of Metal Ions in Polyelectrolyte Films.

We fabricated slippery liquid-immobilized coating (SLIC) films by reacting a slippery liquid (polymethylhydrosiloxane) near the surface of a polyelectrolyte film containing silver ions prepared by the layer-by-layer method. The obtained films maintained their slipperiness after chemical and physical treatments, in contrast to slippery liquid-infused porous surfaces. The high chemical and physical stabilities of the films were attributable to gelation and immobilization of the lubricant owing to an oxidation-reduction reaction with subsequent dehydration condensation of Si-OH on the outer surface of the polyelectrolyte film and the bonding of Si-H with NH2 groups within the polyelectrolyte film, respectively. Moreover, the SLIC films exhibited a high degree of slipperiness with respect to low-surface-tension liquids. To the best of our knowledge, this technique of lubricant immobilization using silver ions has not been reported previously. The films should be suitable for use in various applications where contamination must be prevented under extreme conditions, such as those requiring high physical durability and organic solvent use.

Quantitative structure-property relationship (QSPR) for prediction of CO2 Henry’s law constant in some physical solvents with consideration of temperature effects

Different types of physical solvents have been utilized for CO2 removal from natural gas in the sweetening process. In this work, quantitative structure-property relationship (QSPR) method is suggested to build powerful models to predict Henry’s law constant (HLC) for CO2 in physical solvents. Modeling the HLC for CO2 as a function of molecular descriptors was achieved by multiple linear regression and descriptor selection was by genetic algorithm. The main proposed model has two simple descriptors, including the number of hydroxyl groups and molecular weight of solvents at fixed temperature. Also, the effect of temperature was studied, and this operational variable was added to the mentioned simple descriptors. In this case, the data set is comprised of 77 HLC for CO2 in solvents and at different temperatures. Several internal and external validation methods demonstrated the excellent ability for prediction, and the average relative deviation of main model was 6.48.

Investigation of new control strategies for acid gas absorber columns to improve the response rates using dynamic process simulation

Increasing penetration of intermittent renewable sources of electrical energy such as wind or solar into the energy mix places an increasing demand on the flexibility of other power plant, in particular fossil fuel-based units.The suppliers of natural gas combined cycle equipment have been particularly successful in designing plants with increased ramp rates. In a recent review (Todd et al., 2014) EPRI has analysed the potential for using such equipment to improve the ramp rates of IGCC power plant. The review concluded that this was certainly possible, and identified the limiting equipment to be the acid gas removal system. Experience with such units in chemical applications has shown that at faster ramping rates than about 3%/min, the design sulfur specification cannot be maintained and a short-term sulfur breakthrough occurs. In that review it was postulated that this could be attributed to reduced solvent flow in the lower part of the column, while the hold-up required for higher load operation was being built up.Follow up work has been performed at the Technical University of Darmstadt to verify this hypothesis and propose mitigation measures. A typical tray column using a physical solvent was modeled, initially in ASPEN Plus and then in ASPEN Plus Dynamics. The dynamic model was calibrated against typical performance of industrial plant. The initial hypothesis could be verified and further refined. A number of proposals for mitigation measures were investigated and evaluated. The understanding gained by this work will be applicable also to packed columns and chemical solvents, though in the latter case the model will need to be extended to include kinetic effects.This paper describes the simulation work and a control strategy to improve the ramp rate of an acid gas removal system.

New blends of hydroxypropylmethylcellulose and Gelucire 44/14: physical property and controlled release of drugs with different solubility

New blends of hydroxypropylmethylcellulose (HPMC, 4000 cps) and Gelucire®44/14 (GE) were utilized to modulate the solubility and release rate of poorly water-soluble drug in a controlled manner. HPMC was used as sustained release polymer while GE was blended as a solubilizing carrier. The binary blends of HPMC and GE with proportional ratios (0, 25, 50, 70, 100%) were prepared by three different preparation methods: simple physical mixing, solvent evaporation and hot-melting. The physical properties such as surface morphology, thermal behavior and crystallinity pattern of the binary blends without loading drugs were then characterized using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and powder X-ray diffraction (PXRD), respectively. Finally, the ternary solid dispersions (SD) were prepared by dispersing model drugs in a binary blend. Two model drugs, water-soluble acetaminophen (AAP) and poorly water-soluble pranlukast (PLK) were applied to the binary blends. In case of AAP, HPMC retarded release rate but GE had no significant solubilizing effect due to the high AAP solubility, In contrast, the release rate of PLK was efficiently modulated release rate in a controlled manner with an aid of HPMC and GE. Surely, GE could play a key role in enhancing the dissolution rate while HPMC efficiently controlled release rate of drugs without losing drug crystallinity.

Membrane contactors for process intensification of gas absorption into physical solvents: Impact of dean vortices

Membrane contactors are considered as one of the most promising intensification technologies for gas-liquid absorption processes. For chemical absorption systems, such as flue gas CO2 absorption in amine solutions, the mass transfer resistance is significantly located in the membrane due to the accelerating effect exerted by the reaction in the liquid. For physical absorption systems however, such as CO2 absorption in water for biogas purification, most of the resistance is located within the liquid phase. Process intensification requires an increase of the gas-liquid interfacial area (provided by the membrane) together with increased mass transfer performances in the rate limiting phase, namely the liquid. In the liquid phase, a boundary layer is formed, in which the solute concentration is higher than at the bulk, thus decreasing the driving force for the transfer. This study investigates the use of Dean vortices as a tool to increase mass transfer performance in membrane contactors. These vortices, generated by a helical hollow fiber, are applied to CO2 absorption in water using dense polymeric membranes. A straight hollow fiber with water flowing in the lumen is compared to different helical shaped hollow fibers. Firstly, Dean vortices, calculated by a CFD approach, are successfully compared to the velocity maps experimentally obtained by MRI, a non-invasive spectroscopy. Hydrodynamic simulations are thus validated, offering parametric studies and design optimization perspectives. The experimental results for the mass transfer performances of a hollow fiber under different liquid velocity conditions are further compared to simulations. A parametric study, combining CFD and mass transfer simulations, shows that Dean vortices enable an increase of the mass transfer coefficient by a factor of 3, with a moderate increment in pressure drop or energy expenditure, when compared to the straight fiber. Lastly, the best helical geometry, with maximal CO2 mass transfer at the expense of minimal energy requirement is investigated. For a given application, it is shown that a large process intensification effect is attainable; with the same energy requirement, a 2-fold decrease in the surface area is achieved. The potential of the concept for practical hollow fiber modules design and applications are finally discussed.

Use of Solid Dispersions and Inclusion Complexation for Enhancing Oral Bioavailability of Ziprasidone in Treating Schizophrenia

In modern times, people are suffering from many mental health disorders like schizophrenia, bipolar disorders and many psychoses. Hence, it is essential to treat these mental disorders using medications as well as with assistance from caregivers for the social well being of person. This study was focussed on improving solubility & dissolution of poorly soluble drug Ziprasidone using different formulation approaches like solid dispersion & inclusion complexation. Different solubility enhancing techniques like physical mixing, solvent evaporation, microwave irradiation, lyophilization & spray drying were used for the along with four different polymers i.e Kollidon, Soluplus, Pluronic and HPβCD. The prepared formulations were evaluated for saturated solubility, dissolution, ATR, SEM, XRD, pharmacodynamic and pharmacokinetic in vivo study. The prepare formulations showed increment in solubility as well as dissolution. The order of solubility enhancement for the studied polymers was found to be of following order: Soluplus >HPβCD >Kollidon >Pluronic. In the pharmacodynamic study, the optimized solid dispersion showed the calming effect on mice when compared to pure Ziprasidone. The pharmacokinetic study demonstrated the increase in oral absorption of Ziprasidone in all prepared formulations and it followed the same order as that solubility & dissolution enhancement. The Soluplus-solid dispersion prepared by spray drying technique was found to be suitable in enhancing oral absorption with significant (p < 0.05) enhancement in Cmax & AUC than pure Ziprasidone. Hence, comparative study was helpful in increasing oral bioavailability Of Ziprasidone in choosing the suitable polymer with decreasing the dose and increasing patient adherence to therapy.

Solvent‐Modulated Influence of Intramolecular Hydrogen‐Bonding on the Conformational Properties of the Hydroxymethyl Group in Glucose and Galactose: A Molecular Dynamics Simulation Study

Intramolecular hydrogen‐bonding (H‐bonding) is commonly regarded as a major determinant of the conformation of (bio)molecules. However, in an aqueous environment, solvent‐exposed H‐bonds are likely to represent only a marginal (possibly adverse) conformational driving as well as steering force. For example, the hydroxymethyl rotamers of glucose and galactose permitting the formation of an intramolecular H‐bond with the adjacent hydroxyl group are not favored in water but, in the opposite, least populated. This is because the solvent‐exposed H‐bond is dielectrically screened as well as subject to intense H‐bonding competition by the water molecules. In the present study, the effect of a decrease in the solvent polarity on this rotameric equilibrium is probed using molecular dynamics simulation. This is done by considering six physical solvents (H2O, DMSO, MeOH, CHCl3, CCl4, and vacuum), along with 19 artificial water‐like solvent models for which the dielectric permittivity and H‐bonding capacity can be modulated independently via a scaling of the O–H distance and of the atomic partial charges. In the high polarity solvents, the intramolecular H‐bond is observed, but arises as an opportunistic consequence of the proximity of the H‐bonding partners in a given rotameric state. Only when the polarity of the solvent is decreased does the intramolecular H‐bond start to induce a conformational pressure on the rotameric equilibrium. The artificial solvent series also reveals that the effects of the solvent permittivity and of its H‐bonding capacity mutually enhance each other, with a slightly larger influence of the permittivity. The hydroxymethyl conformation in hexopyranoses appears to be particularly sensitive to solvent‐polarity effects because the H‐bond involving the hydroxymethyl group is only one out of up to five H‐bonds capable of forming a network around the ring.

Cost and performance of some carbon capture technology options for producing different quality CO2 product streams

A techno-economic assessment of power plants with CO2 capture technologies with a focus on process scenarios that deliver different grades of CO2 product purity is presented. The three leading CO2 capture technologies are considered, namely; oxyfuel combustion, pre-combustion and post-combustion capture. The study uses a combination of process simulation of flue gas cleaning processes, modelling with a power plant cost and performance calculator and literature values of key performance criteria in order to evaluate the performance, cost and CO2 product purity of the considered CO2 capture options. For oxyfuel combustion capture plants, three raw CO2 flue gas processing strategies of compression and dehydration only, double flash system purification and distillation purification are considered. Analysis of pre-combustion capture options is based on integrated gasification combined cycle plants using physical solvent systems for capturing CO2 and sulfur species via three routes; co-capture of sulfur impurities with the CO2 stream using Selexol™ solvent, separate capture of CO2 and sulfur impurities using Selexol™, and Rectisol® solvent systems for separate capture of sulfur impurities and CO2. Analysis of post-combustion capture plants was made with and without some conventional pollution control devices. The results highlight the wide variation in CO2 product purity for different oxyfuel combustion capture scenarios and the wide cost variation for the pre-combustion capture scenarios. The post-combustion capture plant with conventional pollution control devices offers high CO2 purity (99.99mol%) for average cost of considered technologies. The calculations performed will be of use in further analyses of whole chain CCS for the safe and economic capture, transport and storage of CO2.

A technical and economic assessment of variants for CO2 separation from synthesis gas

ABSTRACTAn analysis of carbon dioxide (CO2) removal process from synthesis gas has been carried out in this work. CO2 removals by physical and chemical solvents are the most often used. The most important factors that affect cost and performance of a CO2 recovery unit are the number of flash drum separation units, and the pressure drop pattern among them. Different variations of this process were simulated using Hysys software, and the capital and operational expenditures for these plants were estimated. The focus was to reach an optimum process to minimize the total unit cost of separated CO2. The results indicate that for a fixed number of separation units, the case with uniform pressure drop pattern has the minimal cost and energy consumption. On the other hand, it was revealed that among the cases with uniform pressure drop pattern, the one with four separation units will be the optimum case.

Solubility of sulfur compounds in commercial physical solvents and an ionic liquid from Monte Carlo simulations

Natural gas, synthesis gas, and flue gas typically contain a large number of impurities (e.g., acidic gases), which should be removed to avoid environmental and technological problems, and to meet customer specifications. One approach is to use physical solvents to remove the acidic gases. If no experimental data are available, the solubility data required for designing the sweetening process can be obtained from molecular simulations. Here, Monte Carlo (MC) simulations are used to compute the solubility of the gas molecules, i.e., carbonyl sulfide, carbon disulfide, sulfur dioxide, hydrogen sulfide, methyl mercaptan, carbon dioxide, and methane in the commercial solvents tetraethylene-glycol-dimethyl-ether (Selexol), n-methyl-2-pyrrolidone, propylene carbonate, methanol (Rectisol), and the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][Tf2N]). Henry coefficients of the gases in the investigated solvents are obtained from the computed solubilities. The ratio of Henry coefficients is used to compute ideal selectivities of the solvents. The solubilites and selectivities computed from MC simulations are compared with available experimental data. Some guidelines are provided to remove acidic gases using the investigated solvents. Rectisol is the best solvent for acid gas removal, but it should be used at low temperatures. Selexol and the ionic liquid have similar selectivity of sulfur compounds with respect to methane and may be used at elevated pressures and temperatures since both have low vapor pressures. The solubility of carbon disulfide, sulfur dioxide, and methyl mercaptan in these solvents is the highest. Hence, these components can be removed easily prior to hydrogen sulfide, carbonyl sulfide, and carbon dioxide in a pre-absorber.

1,2,3-Trimethoxypropane: A Glycerol-Derived Physical Solvent for CO2 Absorption

1,2,3-Trimethoxypropane (1,2,3-TMP) is the trimethyl ether of propane-1,2,3-triol, better known as glycerol, which can be derived from triglycerides originating from either plant or animal sources. Despite its simple structure and the ubiquity of its glycerol precursor, successful synthesis of 1,2,3-TMP was only recently reported in the literature, with studies suggesting it may be a “green” and nontoxic alternative to solvents such as diglyme, a constitutional isomer. However, no thermophysical properties of 1,2,3-TMP have yet been reported. Furthermore, the structure of 1,2,3-TMP is also analogous to polyether solvents used in the Selexol process for removal of CO2 and other “acid” gases from CH4, H2, etc. As such, examining the solubility of CO2 in 1,2,3-TMP is also of interest. This work details our initial studies and characterization of 1,2,3-TMP as a physical solvent for CO2 absorption, as well as the characterization of its density, viscosity, and vapor pressure with respect to temperature. 1,2,3-...

In-line physical desorption unit—Part 1: Conceptual design and numerical analysis

The large footprint of liquid physical solvent regeneration unit has reduced its feasibility to be employed at offshore condition. The main aim of current work is to design a compact physical desorption unit via computational modelling approach. Two main outcomes obtained from current work include modelling of non-equilibrium desorption phenomenon and introduction of conceptual design for in-line physical desorption unit. The desorption phenomenon was modelled using Computational Fluid Dynamics – Population Balance Model (CFD – PBM) model with integration of bubble nucleation and growth models. The in-line physical desorption unit has been designed based on three design considerations; pressure maintenance in pipeline without using pump, solvent flow rate optimisation, and desorption rate enhancement. The desorption phenomenon in conventional nozzle and initial conceptual design of in-line physical desorption unit were modelled. The CFD modelling approach has been experimentally validated. CFD results were used to analyse the desorption phenomenon in the domain. The pressure drop in the pipeline (inlet) of initial conceptual design was found to be insignificant. The mole fraction of CO2 in water at the outlet was found to experience higher reduction (better desorption) for initial conceptual design (0.0035) as compared to conventional nozzle (0.0053) from inlet mole fraction of CO2 at 0.0064 for both cases. The velocity of gas–liquid has been increased from 5.5m/s (inlet) to 18.5m/s (outlet) in the initial conceptual design. The optimisation of the initial conceptual design of in-line physical desorption unit would be presented in Part 2 of the study.

Lessons Learned from the Use of Unconventional Materials for CO2 Capture

Having worked on several approaches to CO2 capture over the past decade, we have studied a great number of physical and chemical solvents as well as polymer and composite membranes. Initially, most of these materials were based upon ionic liquids (ILs), however due to challenges encountered in applying ILs to meet the demanding requirements in CO2 separation processes, there is a need to reconsider what role (if any) ILs might play in CO2 capture technologies. Ultimately, more promising and robust materials will not come from ILs themselves, but from retrosynthetic analysis and a reconsideration of which structural variables and properties are (and are not) important. The hybridization of the constituent parts into entirely new, yet seemingly familiar substances, can yield greatly improved properties and economics. This manuscript highlights recent work from our group based on lessons learned from ILs that have spurred the development of new amine solvents and polymer materials to better address the demanding process conditions and requirements of CO2 capture and related separations.

Tin Selenide – Multi-Walled Carbon Nanotubes Hybrid Anodes for High Performance Lithium-Ion Batteries

A simple dry physical grinding and solvent mixing approach was used to prepare tin selenide – multiwalled carbon nanotube (MWCNT) hybrid as an anode material for high performance lithium ion batteries (LIBs). The pure tin selenide and their composites with carbon black or graphene oxides were previously reported, however no other groups have reported tin selenide/MWCNT composite as anode materials for LIBs. The new hybrid had superior electrochemical cycling performance with higher reversible (lithiation) capacity of 882 to 651mAhg−1 over 50 cycles compared to pure tin selenide (602 to 58 mAhg−1) or pure MWCNT (339 to 171 mAhg−1) electrodes. The enhanced performance of the tin selenide/MWCNT hybrid was attributed to various factors including alleviation of volume change of tin selenide during lithiation/delithiation by nanoscale network of MWCNT which helped to preserve the electrical connectivity between active particles, reversible decomposition of tin selenide, lithiation/delithiation of MWCNTs and conductive electronic transport pathways provided by MWCNTs.