•A new absorption system of [Bmim][Cl]-organic solvent-CuCl for separation of propylene from propane.•Such a system with lower viscosity and higher propylene solubility (0.064 mol/L at 298 K/2 bar) and selectivity of 6:1.•Regenerability and recyclability of system with negligible activity loss.•A class of new potential absorbent for separation of propylene from propane.To lower viscosity and possible negative effect on mass/heat transfer in industrial operation, we prepared a new absorption system to separate propylene from propane, i.e., ionic liquids (ILs)-organic solvent-cuprous salt. The absorption system is constructed by IL of 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]); organic solvent of pyridine, N,N-dimethylformamide (DMF) or N-methyl-2-pyrrolidone (NMP); cuprous chloride (CuCl). We experimentally measured the absorption capability and selectivity of such a new system for pure propylene, propane or their mixture at 1–7 bar and 298–318 K. We investigated different factors such as temperature, pressure, species of organic solvent, Cu+ concentration and regeneration and recycling of absorbents. The addition of organic solvent significantly lowers the viscosity of absorption system (approximately one order of magnitude lower). Organic solvent interestingly enhances the absorption capability for propylene while suppresses the absorption selectivity slightly. Species of solvent has a huge effect on separation performance. [Bmim][Cl]-pyridine-CuCl gives the best separation performance, e.g., in the absorption of a mixture of 50 mol% propylene and 50 mol% propane, the solubility of propylene in [Bmim][Cl]-pyridine-CuCl-2M (mass ratio of [Bmim][Cl]:pyridine, 10:1) is 0.064 mol/L at 298 K/2 bar while that of propane is 0.0105 mol/L with absorption selectivity of 6.1, which is comparable to some other ILs-Ag+ or ILs-Cu+ absorption systems. Such an absorption system can be regenerated through temperature and pressure swing and recycled without remarkable activity loss. Therefore, this new system is a good potential absorbent for separating propylene and propane.

We synthesized one quaternary ammonium polymeric ionic liquids (PILs)P[VBTHEA]Cl and three imidazolium PILs of P[VEIm]Br, P[VEIm]BF4, P[VEIm]PF6 by free-radical polymerization in solution. These PILs were characterized by FT-IR, 1H-NMR, 13C-NMR, TGA, XRD and SEM. Their CO2 adsorption capacities were measured under different pressures and temperatures by constant-volume technique. It was observed that quaternary ammonium PILs of P[VBTHEA]Cl have higher adsorption capacity for CO2 than those imidazolium PILs, following P[VBTHEA]Cl > P[VEIm]PF6 > P[VEIm]BF4 > P[VEIm]Br, which may be ascribed to higher positive charge density on ammonium cation than that on imidazolium cation and thus stronger interaction with CO2, consistent with the results from dual-mode adsorption model that ammonium PILs have much higher CO2 bulk absorption than imidazolium PILs. CO2 adsorption capacity of P[VBTHEA]Cl is 9.02 mg/g under 295 K and 1 bar, which is comparable to that of some other PILs, and is much higher than that of the corresponding ILs monomer. These PILs have good adsorption selectivity for CO2 over N2 and regeneration efficiency.A new class of CO2 adsorbents: polymeric ionic liquids material with high CO2 adsorption capacity & selectivity and good cycling.Download high-res image (342KB)Download full-size image

Isobaric vapor–liquid equilibrium (VLE) values at 101.3 kPa of binary methyl acetate + methanol, binary methyl acetate + ionic liquids (ILs), binary methanol + ILs, and ternary methyl acetate + methanol + ILs are measured, where the ILs are 1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP]), 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]), and 1-butyl-3-methylimidazolium dibutylphosphate ([BMIM][DBP]). The azeotropic point of methyl acetate + methanol is removed with addition of ILs, and [MMIM][DMP] gives the largest effect, followed by [EMIM][DEP] and [BMIM][DBP]. Salting-out effect from ILs is observed where the relative volatility of methyl acetate is increased. The minimum amount of such phosphate ILs required to break the azeotropic point is remarkably less than that of some other ILs; also such phosphate ILs are fluorine-free and easily prepared with cheaper starting materials. The experimental VLE data are correlated well with electrolyte NRTL model.

•CFD method was integrated with factorial design to reveal particle suspension.•Solid-liquid mixing performance of four typical impellers was compared.•Regression models for floating and sinking particles suspension were achieved.•Impeller optimization was proposed upon particle suspension and mixing energy.The present study focuses upon the effect of the impeller on sinking and floating behavior of suspending particles in stirred tank reactor, employing computational fluid dynamics (CFD) simulation where factorial design is used to investigate the main and interaction effects of design parameters on the particle distribution performance of four typical impeller designs. Factorial design results show the effect of diameter and width of the impeller and off-bottom clearance on sinking particles is different from that of floating particles and regression equations for sinking particles and floating particles are achieved separately. Meanwhile, optimal equations which quantitatively reveal the effect of impeller factors on suspension quality and energy input is established for impeller improvement. Besides the development of computational models, the combination of CFD simulation with factorial design method provides a useful approach to gain insight into the suspension behavior of sinking and floating particles, also it guides to optimize the impeller design.Download high-res image (88KB)Download full-size image

Annually the transport sector consumes a quarter of global primary energy and is responsible for related greenhouse gas emissions. Presently, petroleum derived liquid fuels are the overwhelming source of energy for the transport sector. Liquid biofuels are a viable substitution for petroleum-derived fuels in the transport sector and an important option to mitigate greenhouse gas emissions, especially CO2 emissions. Substituting petroleum-derived fuels with liquid biofuel is also anticipated to reduce the dependency of the transport sector on fossil fuels. Different options are available for the production liquid biofuels. However, the production of liquid biofuels from lignocellulosic biomass has certain advantages. These advantages include the high abundance, availability, low procurement cost and current under-utilization of lignocellulosic biomass. However, the potential for successful deployment of technologies to produce liquid biofuel from lignocellulosic biomass and their cost reductions are surrounded by large uncertainties. High cost of production of liquid fuels from lignocellulosic biomass and their commercial immaturity are major obstacles for the widespread application of liquid biofuels in transportation. Other obstacles include the lack of infrastructure and lack of political as well as public support. This article reviews the obstacles behind the limited production of biomass to liquid (BTL) fuels and their diffusion in the transport sector. The potential approaches to make the production of lignocellulosic-based liquid biofuels economically attractive are also discussed. An approach that focuses on integrating individual operations and processes and adequately modelling these processes evaluated on the bases of the entire pathway can help in realizing the large scale commercial production of liquid biofuels through cleaner production.

•Mutual solubility of 1830 ILs and fuel oil were studied with COSMO-RS calculation.•IL micro-structures were characterized by energy, σ-profile and σ-moment.•Mutual solubility is dependent on ionic structure and vdW and HB interactions.•Mutual solubility between selected ILs and fuel oil were determined experimentally.•[C1pyr]H2PO4 were screened out to perform extractive desulfurization experiments.Extractive and oxidative desulfurization of fuel oil using ionic liquids (ILs) as solvents have been intensively studied recently. In such processes, the mutual solubility of ILs and fuel oil is still a major concern. Less mutual solubility is desired to reduce the loss of ILs and the contamination of fuel oil. To screen the ideal ILs with less mutual solubility with fuel oil and to understand the effects of ILs structural characteristics on the mutual solubility, we employed Conductor-like Screening Model for Real Solvents (COSMO-RS) to calculate the mutual solubility of 1830 ILs and model fuel oil. The influences of ILs structural characteristics such as cationic nature, cationic alkyl chain length, cationic symmetry, anionic nature, anionic alkyl chain length and functional group on the mutual solubility are investigated from micro-level view with σ-profile, σ-moment and COSMO-RS energies. The mutual solubility is strongly dependent on cation or anion species and is highly influenced by van der Waals (vdW) and hydrogen-bonding (HB) energies. Cations with smaller non-polarity, shorter alkyl chain length and less symmetry tend to have weaker vdW energies and smaller mutual solubility, while anions with larger polarity tend to have stronger HB energies and smaller mutual solubility. The functional groups also show remarkable effects on mutual solubility; those functional groups that decrease the non-polarity and vdW energies or increase the polarity and HB energies favor the small mutual solubility. Moreover, experimental determinations of the mutual solubility indicate [C1pyr]H2PO4 is a good solvent for desulfurization. This work provides the theoretical basis to design and select the ILs, which have small mutual solubility with fuel oil.

We experimentally studied the catalytic performances of a series of Brönsted-Lewis acidic N-methyl-2-pyrrolidonium metal chlorides ([Hnmp]Cl/MClx, where M=Fe, Zn, Al, or Cu) for the hydrolysis of microcrystalline cellulose (MCC) and cotton to produce reducing sugar. A variety of factors, such as temperature, time, ionic liquid (IL) species, IL dosage, and the concentration of the metal chloride were investigated. [Hnmp]Cl/FeCl3 presented the best hydrolysis performance, affording a 98.8% yield of total reducing sugar from MCC (1 h, 100 °C, 0.1 g MCC, 0.2 g acidic IL, 2.0 g [Bmim]Cl as solvent), which is better than or comparable to results previously obtained with other–SO3H functionalized acidic ILs. The hydrolysis performances of [Hnmp]Cl/MClx were rationalized using density functional theory calculations, which indicated that interactions between the metal chlorides and the cellulose, including charge-transfer interactions are important in the hydrolysis of cellulose and degradation of glucose. This work shows that Brönsted-Lewis acidic ILs are potential catalysts for the hydrolysis of cellulose to produce sugar.

Study on alternative methods to hydrodesulfurization is always an interesting area, because of the ineffectiveness for hydrodesulfurization to remove some cyclic sulfur compounds (S-compounds) and the high cost from harsh operation conditions and expensive catalyst, among which oxidative desulfurization (ODS) using ionic liquids (ILs) as solvent is intensively studied recently. Here, we synthesize a series of Brønsted–Lewis acidic ILs of N-methylpyrrolidonium zinc chloride ([Hnmp]Clx/(ZnCl2)y, x:y from 2:1 to 1:2) and investigate the ODS of both model diesel fuel composed of n-octane and dibenzothiophene and real FCC feedstock where such ILs are used as extractant and catalyst and 30 wt % H2O2 is used as oxidant, involving the factors such as IL composition (or x:y), temperature, dose of oxidant (or molar ratio of O/S), dose of IL (or mass ratio of IL/oil), recycling of IL and multistage desulfurization. IL composition has an important effect on sulfur removal (S-removal) efficiency, and [Hnmp]Cl/ZnCl2 (x:y = 1, the structure nature was characterized with ESI-MS and FT-IR) shows the highest desulfurization capability with good recyclability. With [Hnmp]Cl/ZnCl2, the S-content in model diesel fuel can be reduced to <1 ppm from 500 ppm with 99.9% S-removal at 75 °C, IL/oil = 1/3 and O/S = 8 after only one stage, while the sulfur removal for real FCC diesel fuel is less than 38% in one stage and can reach 83% after five stages, which might be ascribed to more-complex S-species in real fluidized catalytic cracking (FCC) diesel fuel as indicated by gas chromatography–sulfur chemiluminescence detection (GC-SCD) chromatogram analyses. The sulfur content (S-content) in FCC diesel fuel, however, can be reduced to 5.3 ppm with a total S-removal of 97.6% after five-stage ODS with one more extractive desulfurization with furfural as the extractant. This work shows that such Brønsted–Lewis acidic ILs are potential solvents used in ODS to produce clean fuel oils.

•New IL absorbents with Cu+ are prepared for separation of propane and propylene.•Absorption capability and selectivity are determined at 1–7 bar and 298–318 K.•Separation capability are comparable to expensive ILs-Ag+, and better than pure ILs.•Such absorbents can be regenerated simply without remarkable activity loss.Ionic liquids (ILs) coupled with Ag+ or Cu+ salts to form a new kind of reactive absorbent have been studied to separate light olefin from paraffin recently. In this work, we prepared two halogen-free alkylimidazolium thiocyanate ILs with cheaper cuprous thiocyanate, i.e., [Bmim]SCN–CuSCN and [Emim]SCN–CuSCN (Bmim, 1-butyl-3-methylimidazolium; Emim, 1-ethyl-3-methylimidazolium) and investigated their absorption capability for propylene, propane and mixture of both at 1–7 bar and 298–318 K. The effects of operating parameter including cation nature, temperature, pressure, Cu+ concentration and reuse of absorbent were investigated. Propylene shows a chemical absorption while propane does a physical one, and increasing Cu+ concentration effectively improves the absorption capability for propylene and the selectivity of propylene/propane. [Bmim]SCN–CuSCN has higher absorption capability and selectivity for propylene than [Emim]SCN–CuSCN, e.g., [Bmim]SCN–CuSCN-1.5 M can absorb 0.12 mol of propylene per liter while 0.012 mol of propane per liter at 1 bar and 298 K, with a selectivity of 10, which is comparable to some other ILs-Ag+ salts and better than pure ILs. Such absorbents can be regenerated through temperature and pressure swing without remarkable activity loss. This work shows that alkylimidazolium thiocyanate ILs with Cu+ salts are promising reactive absorbents to separate propylene from propane.

To screen and use ionic liquids (ILs) as environmental-friendly extractive solvents in removing aromatic sulfur compounds (S-compounds) from fuel oils, the knowledge of their capacity for S-compounds (or solubility of S-compounds in ILs) is very important. In this work, the capacities of 1860 potential ILs (30 anions, 62 cations) for two representative S-compounds of thiophene (TS) and dibenzothiophene (DBT) are calculated using conductor-like screening model for real solvents (COSMO-RS). The influences of cation family, cation alkyl chain length, cation symmetry, anion nature, anion alkyl chain length, and functional group on the capacity are extensively discussed and are understood from microlevel view with σ-profile, σ-moments, and COSMO-RS energies. It is observed that the capacity is very dependent on cation and anion structure characteristics and is in a very wide range (e.g., 10–3∼101 for TS, 10–3∼102 for DBT); the van der Waals (vdW) and hydrogen-bonding (HB) energies have significant effects on the capacity. Increasing the nonpolarity and vdW energies of cation or alkyl chain on anion, or the polarity and HB energies of anion, can favor the capacity. This work is valuable to rationally select or design the ILs for desulfurization of fuel oils.

•Five functional Brønsted or Brønsted–Lewis acidic ILs are prepared.•Such acidic ILs act as both extractive and catalytic solvents in desulfurization.•S-content in diesel fuel is reduced to <10 ppm through coupled EDS–ODS.•Desulfurization condition is mild with very low loss of desulfurization efficiency.•Nature of S-compounds in diesel fuel is determined by GC-SCD.Desulfurization of diesel fuel with ionic liquids (ILs), as alternative to traditional hydrodesulfurization (HDS), has been studied intensively for the latest years. Most works, however, were focused on the investigation of model diesel fuel. In this work, two acidic ILs ([(CH2)4SO3HMIm][Tos] and [(CH2)4SO3HMIm][ZnCl3]) were synthesized and studied their desulfurization performance for real diesel fuel in a coupled oxidative–extractive way, where 30 wt% H2O2 acted as oxidant and ILs served as both extractants and catalysts with adding no acidic catalysts that were usually used in traditional oxidative desulfurization. The influences, on desulfurization, of temperature, time, mass ratio of ILs/oil, molar ratio of O/S, multiple desulfurization and ILs recycle were investigated. It was observed that sulfur content (S-content) in the real diesel fuel was reduced to <10 ppm from original 225 ppm in a coupled oxidative–extractive way ([(CH2)4SO3HMIm][Tos]; mass ratio of ILs/oil 1/2; 3 h, 348.15 K and molar ratio of O/S 40/1 in oxidative step; 30 min and 333.15 K in extractive step). These results are more competitive than other previous results. After 5 cycles of oxidative desulfurization with used ILs, the loss of efficiency is less than 1% at a mild temperature. Distribution of S-compounds in diesel fuel before and after desulfurization were determined by gas chromatograph with sulfur chemiluminescence detector. This work shows that such acidic ILs are capable of removing S-compounds effectively from real diesel fuel with a coupled oxidative–extractive operation.

Isobaric vapor–liquid equilibrium (VLE) at atmospheric pressure (101.3 kPa) for the binary systems of acetone + methanol, acetone + phosphate ionic liquids (ILs), and methanol + phosphate ILs, and for the ternary system of acetone + methanol + phosphate ILs are measured using a circulation VLE still. The phosphate ILs include 1,3-dimethylimidazolium 1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP]), 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]), and 1-butyl-3-methylimidazolium dibutylphosphate ([BMIM][DBP]). The addition of these phosphate ILs to the azeotropic acetone + methanol system results in a salting-out effect on acetone and makes the azeotropic point disappear. The relative volatility α12 of acetone over methanol increases with increasing molar fraction of ILs. The equilibrium data were well fitted by the electrolyte nonrandom two-liquid model (e-NRTL). Compared with some reported ILs previously such as pyridinium hexafluorophosphate, imidazolium trifluoromethane sulfonate and imidazolium dicyanamide, such imidazolium phosphate ILs are fluorine-free, are prepared more simply with lower cost, and make the azeotropic point disappear at less added amount of ILs. This work shows that such phosphate ILs are a class of potential solvents to separate azeotropic acetone + methanol system.

•Lewis/Brφnsted acidic ILs in this work were proved to be capable of removing S-/N-compounds effectively from fuel oils.•More than 90% extractive efficiency was realized after a single extraction of N-compounds from fuel oils.•Influence of temperature, IL:mass ratio, multiple extractions on efficiency were tested.•Good recyclability showed the ideality of [Bmim]Cl/ZnCl2 in industrial application.Due to the ineffectiveness in removing cyclic sulfur compounds (S-compounds) and nitrogen compounds (N-compounds) such as thiophene (TS), dibenzothiophene (DBT), carbazole, pyridine and their derivatives from fuel oils, the traditional hydrodesulfurization and hydrodenitrogenation processes are facing some challenges especially now in the wake of sterner regulation of S-/N-content in fuel oils. This work demonstrates that some acidic ionic liquids (ILs) are capable of extracting cyclic S-/N-compounds particularly the basic N-species from fuel oils. Both Lewis acidic ILs 1-butyl-3-methylimidazolium chloride/ZnCl2 ([Bmim]Cl/ZnCl2) and [Bmim]Cl/2ZnCl2 as well as Brφnsted acidic ILs [Bmim]HSO4 and [Hmim]HSO4 are used to extract TS, DBT, carbazole and pyridine from their hexane (model gasoline) or octane (model diesel fuel) mixtures. Typically, 93.8% TS removal (S-content drops from 500 ppm to 31 ppm) and 95.9% DBT removal (S-content from 516 ppm to 21 ppm) by [Bmim]Cl/ZnCl2 after 6-stage extraction are obtained at 25 °C, 1:1(w/w)IL:oil, 30 min; while 93.8% carbazole removal (N-content from 279 ppm to 17 ppm) and 97.8% pyridine removal (N-content from 495 ppm to 11 ppm) are realized after only one stage extraction and the N-content is undetectable after 2-stage extraction. [Bmim]Cl/ZnCl2 is selected as a representative IL to undergo a series of parallel experiments to determine the influence of extraction time, temperature, IL:oil mass ratio and multi-stage extraction on S-/N-removal efficiency. The mutual solubility of [Bmim]Cl/ZnCl2 in fuel oil as well as IL recycling is also performed.

In this work, four quaternary ammonium-based ionic liquids are used to extract methyl orange and methylene blue (major dye species in industry) from water. The influence of extraction time, temperature, salt effect, and pH on extraction efficiency is systematically investigated. Tricaprylmethylammonium thiocyanate ([N1888][SCN]) exhibits optimal ability for extracting both dyes; the extraction efficiency reaches 89.09% and 64.14% for methyl orange and methylene blue, respectively. It is also observed that the efficiency is remarkably increased by adding NaCl in the extraction system except in the extraction of methyl orange using [N1888][SCN]. This work shows that ionic liquids might provide new options in the disposal of dye-wastewater.Highlights► New quaternary ammonium-based ILs are used to extract soluble dyes. ► Quaternary ammonium-based ILs are very stable for extraction. ► Significant effects of extraction are interestingly observed. ► This work shows a new option for dealing with dyes wastewater.

•VLE data for methanol + DMC + phosphoric-based ionic liquids measured at 101.3 kPa.•The azeotropic point is totally eliminated by ILs investigated at xIL > 0.15.•The ILs have a great salting-out effect, which enhances the relative volatility of DMC.•The e-NRTL model can correlate the experimental VLE data with a good accuracy.•The ILs investigated are promising entrainers for the separation of methanol and DMC.Isobaric vapor–liquid equilibrium (VLE) at 101.3 kPa for methanol + 1-methyl-3-methylimidazolium dimethylphosphate ([MMIM][DMP]), dimethyl carbonate (DMC) + [MMIM][DMP], methanol + 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]), and DMC + [EMIM][DEP] binary systems, as well as the VLE for the methanol + DMC + [MMIM][DMP] and methanol + DMC + [EMIM][DEP] ternary systems are measured using a circulation VLE still. With the addition of ionic liquids into the azeotropic system of methanol + DMC, the relative volatility of DMC is enhanced, which shows a salting-out effect of ionic liquids. The azeotropic point disappears when the mole fraction of ionic liquids is above 0.15. The salting-out effect on the DMC produced by [MMIM][DMP] is stronger than that produced by [EMIM][DEP]. The equilibrium experimental data is well correlated by the electrolyte nonrandom two-liquid model.Potential entrainers for the separation of methanol and DMC in extractive distillation.

Isobaric vapor–liquid equilibrium at 101.3 kPa for the ternary system methanol + dimethyl carbonate +1-butyl-3-methylimidazolium dibutylphosphate ([BMIM][DBP]) and their binary systems are determined using a modified Othmer still. By adding [BMIM][DBP] into the azeotropic system of methanol + dimethyl carbonate, the relative volatility of dimethyl carbonate is increased, which might be ascribed to the salting-out effect of [BMIM][DBP]. The relative volatility α21 increases with increasing molar fraction of [BMIM][DBP]. The azeotropic point disappears when the molar fraction of [BMIM][DBP] is above 0.150. The equilibrium data are well fitted by the electrolyte nonrandom two-liquid model.

A series of Lewis acidic ionic liquids (ILs) based on 1-n-butyl-3-methylimidazolium metal chloride, i.e., [C4mim]Cl/MCl2 (M = Zn, Fe, Cu, Mg, Sn, Co), are synthesized and used to investigate the oxidative removal of sulfur compounds (S-compounds) from diesel fuels, with ILs serving as both extractant and catalyst and 30 wt% H2O2 solution as oxidant. It is observed that metal chloride species affect S-removal, as S-removal efficiency follows the order: [C4mim]Cl/ZnCl2 > [C4mim]Cl/FeCl2 > [C4mim]Cl/CoCl2 > [C4mim]Cl/MgCl2 > [C4mim]Cl/CuCl2 > [C4mim]Cl/SnCl2. The highly efficient [C4mim]Cl/ZnCl2 is selected to investigate the effects of ZnCl2 content on desulfurization. It is interesting to find out that ZnCl2 content has a significant influence on desulfurization; specifically, 99.9% S-removal is observed for [C4mim]Cl/3ZnCl2 after 3 h at 45 °C, O/S molar ratio of 8, IL/oil mass ratio of 1/2. [C4mim]Cl/3ZnCl2 then undergoes series of parallel experiments to systematically investigate the influence of factors such as temperature, molar ratio of O/S, mass ratio of IL/oil, and ILs recycling. The incorporation of real diesel fuel into this study demonstrates the efficacy of this IL in desulfurization. This work shows that oxidative desulfurization using Lewis acidic ILs may be a new option for producing cleaner diesel fuels.Graphical abstractDeep oxidative desulfurization of diesel fuels by Lewis acidic ILs (a. IL; b. IL, model oil and H2O2; c. oxidized product).Highlights► New extractive-catalytic systems of Lewis acidic ILs are developed for ODS. ► Such Lewis acid ILs are easily manufactured with lower cost on a large scale. ► S-contents of <1 ppm in model diesel fuel and <50 ppm in real oil can be obtained. ► Significant influence from anionic species on ODS is interestingly observed. ► This work shows a new option for producing cleaner diesel fuels.

•[bmim][BF4] and [bmim][PF6] are two efficient absorbents for CO2 capture.•A new ILs-based CO2 capture process is developed and simulated.•Negligible corrosion and solvent loss problems in such a process.•Energy consumption in IL-based process is >25% lower than that in MEA-based process.•ILs-based CO2 capture process is a very promising alternative technology.This study was aimed to simulate a new ionic liquids (ILs)-based CO2 capture process which is useful to capture CO2 from model flue gas, by using two promising CO2 absorbents, 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]). Thermodynamic properties such as vapor pressure, heat capacity and density were modeled. Vapor-liquid equilibrium (VLE) data were calculated by Redlich-Kwong (R-K) equation and NRTL model. The calculated VLE data were in good agreement with the experimental values. This ILs-based CO2 capture process is characterized with few advantages such as there is no issue of water; solvent (ILs) loss is negligible as compared to monoethanolamine (MEA)-based CO2 capture process (e.g., 0.299 g/tCO2 for [bmim][BF4] and 0.391 g/tCO2 for [bmim][PF6] respectively, while 178 g/tCO2 for MEA); potential corrosion risk is excluded; the energy consumption in [bmim][BF4]- and [bmim][PF6]-based processes are lowered up to 26.7% and 24.8% respectively than that in MEA-based process. Thus, such an ILs-based CO2 capture process is more competitive than traditional MEA-based CO2 capture process.

•Properties of feedstock LCM and pre-treatment operation play a vital role.•Proper pretreatment method increase access to fermentable sugars thereby improving the efficiency of the whole process.•In this review paper, intensive fundamental and applied research of each pretreatment process is reviewed.Cost effective pretreatment is key to commercial success of use of lignocellulosic material (LCM) as feedstock for production of bioethanol. The seasonal nature and annual variability of LCM may enforce the use of different biomass sources as feedstock to ensure round the year production. However, different processing requirements of each material may limit the success of such development and impair the use of many feedstocks due to logistic and economic reasons. The selection of pretreatment technology for different LCM sources in cost effective manner is a major challenge. The recent review articles have provided the details of different pretreatment operations. This article has tried to establish a strong connection between pretreatment options and their combination with prior and post pretreatment processes, which is pre-requisite to success of establishing the commercial facility. The key is lessening number of operations and operating cost of each unit of operation. This paper suggests ways towards appropriate pretreatment processes through process intensification leading to the prospects of sustainable biofuel production.Download high-res image (90KB)Download full-size image