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Widely available natural layered expandable clay minerals (smectites) can sorb carbon dioxide in their interlayer space under specific conditions and hence may show potential for gas separation or carbon sequestration processes. This work presents experimental adsorption and desorption measurements of gaseous, sub-critical carbon dioxide (p = 0.1 bar up to 20 bar, T = −20 °C up to 300 °C) on well-characterized anhydrous smectite (Wyoming montmorillonite) and focuses on the effect of the interlayer cation (size). Using seven alkali and alkaline-earth metal cations and three quaternary ammonium cations, a wide range of ionic radii are studied. Physisorption of CO2 in the interlayer space is confirmed via infrared spectroscopy measurements. The results show that optimally sized interlayer cations─comparable to the thickness of a carbon dioxide monolayer─open the interlayer space to make it easily accessible for CO2 up to 1.7 mmol g–1. In particular, Cs-exchanged and tetramethylammonium-exchanged montmorillonite facilitate the rapid sorption of carbon dioxide even at ambient pressure and temperature. These results provide valuable insights into the applicability of widely available natural adsorbent clays for carbon capture and sequestration for the mitigation of climate change.

This paper presents a method to determine the minimum amount of a catalyst needed to operate a heterogeneously catalyzed reactive distillation column based on kinetic and VLE data only, avoiding rigorous column simulations. Good initial estimates for catalyst loadings are rarely discussed, and shortcut methods are lacking. The described method determines the highest possible reaction rate using known kinetics and column stage temperatures obtained from ternary diagrams of the column top and bottom sections, neglecting the highest or lowest boiler of the column, respectively. The method was validated against several literature cases. From these cases, it could be determined that a conservative estimate for the amount of the catalyst in the early design phase is six times the minimum catalyst found using the method described. Additionally, the presented method provides information regarding the operability of the column, for example, related to catalyst deactivation.

2,5-Furan dicarboxylic acid (FDCA) is a promising intermediate for producing polyethylene furan dicarboxylate, an alternative to polyethylene terephthalate that combines a significantly lower greenhouse gas footprint with better mechanical and gas barrier properties. This work presents a process design and techno-economic evaluation for producing FDCA from non-edible biomass via the oxidation of furfural to furoate salt, and subsequent carboxylation to furandicarboxylate salt. Major technical uncertainties are associated with the possible polymerization of furfural in the oxidation step and the state of salt phase in the carboxylation step. Based on the furfural market price of $1400/ton this process requires a minimum selling price of 2000 ± 500 $/ton FDCA. To compete with purified terephthalic acid (PTA), it requires a premium of 100% for better performance and sustainability, or a combination of much cheaper furfural and a much lower capital expenditures (CAPEX).

BACKGROUND: Phenol is used as a raw material in the polycarbonate industry and as the incentive for bio-based plastics and products is increasing, so is the interest in and demand for bio-based phenols. In renewable phenol production processes based on biomass, impurities derived from the biomass, including other oxygenate compounds, are expected in the phenol containing solution. Vapor–liquid equilibrium (VLE) of phenol and 2-Octanone was studied and impact of impurities thereon to gain insights applicable for similar systems in biorefineries for renewable phenol production. RESULTS: For the binary mixture of phenol - 2-octanone azeotropic VLE behavior was found. The effects of ternary compounds on the molecular interactions between phenol and 2-octanone were studied using isothermal calorimetry (ITC) and molecular modelling (MM), and the impact on the VLE behavior was measured using an ebulliometer. CONCLUSION: It was found that the relative volatility could be improved by adding solvents that are polar and/or contain hydrogen bond accepting groups. Ketones and ethers most strongly improved the relative volatility of the binary mixture 2-octanone – phenol. Addition of a linear alkane, a repelling component especially for 2-octanone, strongly improved the relative volatility as well. ITC and MM results, providing heat of mixing and the interaction energy of mixture components, improved fundamental understanding of the molecular interactions between phenol, 2-octanone and ternary compounds, and supported the VLE findings.

We measured the reaction kinetics of the electrochemical reduction of CO2to formate on Pd/C and evaluated several proposed mechanisms, by comparing model-described and observed rates of formation of HCOO-and H2as a function of several parameters (pH2,pCO2, and potential). An α-/β-hydride mechanism, based on an α-hydride phase active for CO2reduction and a β-hydride Pd-phase active for hydrogen evolution, described the experimental data of our and other laboratories reported in the literature satisfactorily. After parametrization, using a data set including only H2, this mechanism also predicted the outcome of D2isotope labeling experiments correctly. Analyses of the results indicate that the α-/β-hydride ratio and hydride formation rate are key factors affecting the formate production rate and the selectivity, thereby identifying areas for further (spectroscopic) studies and mechanism validation.

Xylose is a promising feedstock for the fuel and chemical industry. We propose here an integrated process to recover and purify xylose from an acidic hydrolysate stream, e.g., coming from pretreated lignocellulose. This process consists of selectively extracting the xylose as the diboronate ester and back-extracting it into a clean aqueous solution. We report 85% xylose extraction efficiency using toluene/phenyl boronic acid in a single stage. We show that the extraction procedure is compatible with acidic and basic xylose feed (from pH 1 to 12), does not need a phase transfer agent (such as Aliquat), is strongly selective for xylose, and proceeds best with aromatic solvents. We demonstrate the structure of the diboronate ester by means of 2D-NMR and show evidence for the intermediate formation of a monoboronate ester. The release of xylose from the diboronate ester is explored, and an integrated process for xylose purification is proposed and its boundaries are discussed.

Short polyols, such as ethylene glycol (EG), are a popular target of catalytic hydrogenolysis of saccharides. However, studies on the use of untreated or pretreated lignocellulosic biomass as feedstock for polyol production are scarce. In this work, we have studied the impact of lignin on the catalytic hydrogenolysis of different biomass samples, targeting ethylene glycol. We first developed a hydrogenolysis protocol that is sensitive to lignin and feedstock impurities, such as ash and extractives. A matrix of biomass feedstocks with varying lignin content has been evaluated, by subjecting poplar, pine, and hay to solvent-based (water/ethanol/acetic acid) pretreatments and by preparing physical mixtures of pure microcrystalline cellulose with organosolv lignin. Lignin appeared to inhibit the activity of the hydrogenation catalyst, Raney-Ni, by hindering the formation of sugar alcohols in the presence as well as in the absence of the tungstate catalyst. However, lignin is not the root cause for the low EG yield typically obtained with untreated lignocellulose, as treated lignocellulose delivered high EG yields (30-35 wt %), irrespective of the lignin concentrations, which varied between 0 and 44 wt %, under identical demanding experimental conditions.

BACKGROUND: Although phenol is a key intermediate in the plastics and polycarbonate industry, it is also a toxic component that requires removal from dilute aqueous streams, potentially by liquid–liquid extraction (LLX). For LLX, cumene is suggested as a solvent as it is already present in processes in the polycarbonate industry. For the recovery of cumene from phenol by distillation, knowledge on vapor–liquid equilibrium (VLE) behavior is important, in combination with how this is affected by other components possibly present as an impurity or explicitly added as a solvent. This was investigated in this work. RESULTS: The binary cumene–phenol system shows a tangent pinch in the binary VLE diagram. Addition of a range of impurities and solvents showed that hydrogen bond accepting compounds strongly improve the relative volatility of the mixture, whereas dodecane, not capable of forming hydrogen bonds, has a negative effect on the relative volatility. CONCLUSION: Addition of polar components with hydrogen bonding abilities, i.e. ketones or ethers, affected the relative volatility of cumene over phenol the most positively. Combining two types of components results in similar effects, and clear synergistic effects could not be shown based on current VLE measurements. Addition of an apolar component in combination with polar components with hydrogen abilities had only a minor effect on the relative volatility.

We show the effective conversion of xylose into furfural, with a selectivity >90 mol%, in an aqueous-organic three-solvent system, which is composed of an apolar aromatic solvent, a polar organic solvent and acidic water and helps in catalyzing the formation of furfural. We couple this with a pre-extraction step of xylose as a boronic diester into a promising integrated process for valorising a diluted xylose hydrolysate. This process promises facile recovery of furfural and good recycling of all solvent components. The use of the boronic diester was found to be irrelevant for obtaining high selectivity, as its hydrolysis under the reaction conditions is fast. Surprisingly, the >90 mol% selectivity requires the three-solvent system to transition from biphasic to monophasic under the reaction conditions. Phenylboronic acid (PBA) used to extract xylose was found to be instrumental to this transition; PBA-lean media ( 20 mM resulted in the highest observed xylose-to-furfural selectivity (95 mol%).

Various solvents such as ionic liquids, deep eutectic solvents, and aqueous two phase systems have been suggested as greener alternatives to existing extraction processes. We propose to add macroscopic complex coacervates to this list. Complex coacervates are liquid-like forms of polyion condensates and consist of a complex of oppositely charged polyions and water. Previous research focussing on the biological significance of these polyion-rich phases has shown that polyion condensates have the ability to extract certain solutes from water and back-extract them by changing parameters such as ionic strength and pH. In this study, we present the distribution coefficients of five commonly used industrial chemicals, namely lactic acid, butanol, and three types of lipase enzymes in poly(ethylenimine)/poly(acrylic acid) complex coacervates. It was found that the distribution coefficients can vary strongly upon variation of tunable parameters such as polyion ratio, ionic strength, polyion and compound concentrations, and temperature. Distribution coefficients ranged from approximately 2 to 50 depending on the tuning of the system parameters. It was also demonstrated that a temperature-swing extraction is possible, with back-extraction of butanol from complex coacervates with a recovery of 21.1%, demonstrating their potential as extraction media., Macroscopic complex coacervates can be used to extract compounds from aqueous supernatants. Compound partitioning depends on the ionic strength, complex composition, and temperature. These findings show their potential as aqueous extraction media.

Deep eutectic solvents (DES) have been proposed as solvents for biomass delignification. This paper describes a conceptual process design for the delignification of Eucalyptus globulus using a DES comprised of 30 wt % choline chloride and 70 wt% lactic acid. In this design, the lignin and hemicellulose by-products are recovered by liquid–liquid extraction using 2-MTHF as solvent. Material and energy balances were made and the energy usage of the process was optimized with additional experiments. The amount of DES was reduced to the minimal amount required to fill the porous biomass (5 kg per kg wood), which only reduced the delignification from 94% to 87% and increased the yield from 57 to 59%. Direct recycling of lignin-in-DES mixtures without lignin removal by liquid–liquid extraction to the delignification stage may save energy, but increased repolymerization increases the lignin’s molar weight, which decreases its value and makes recovery by liquid–liquid extraction more difficult. After optimization, the total heat duty of the proposed process is 7.9 GJ/t pulp, which is 28% lower than the kraft process. The main benefit of DES based delignification processes is the possible valorization of byproducts, such as lignin and furans from hemicellulose.

Electrochemical reduction of CO2 on a Pd/C cathode produces formate and hydrogen at low overpotentials. We report on an innovative, effective approach to prevent hydrogen formation. By applying 4 bar partial hydrogen pressure, hydrogen evolution can be fully avoided at −0.05 V vs. RHE and 1 bar partial CO2 pressure.

Dihydrolevoglycosenone, commercially known as Cyrene, is a versatile biobased solvent reported for various applications including being a medium of chemical reactions and membrane manufacture. In this work, application of Cyrene in liquid-liquid extractions has been investigated. Four ternary systems have been assessed at 298.15 K, 323.15 K, and 348.15 K, keeping Cyrene and methylcyclohexane constant and changing the third compound to toluene, cyclohexanol, cyclohexanone, and cyclopentyl methyl ether. Studying these selected ternary systems yielded an indication of applicability of Cyrene in related industrial separation processes such as aromatic/aliphatic separations and in separations of oxygenates in the cyclohexane oxidation process. Key factors are biphasic system formation, distribution coefficients, and selectivity. All ternary systems showed type I liquid-liquid phase behavior with a selective extraction of ternary components from methylcyclohexane by Cyrene. The highest selectivity at 298.15 K was found for cyclohexanol with 61.4 ± 4.33, followed by cyclohexanone with 44.1 ± 8.63, while toluene and cyclopentyl methyl ether had a selectivity of, respectively, 12.0 ± 0.89 and 6.4 ± 0.08. Although Cyrene is applicable in all four ternary systems, the miscibility gap is narrow for the oxygenated species, indicating a limited operation window for liquid-liquid extraction which will be more severe at higher temperatures. Overall, the studies showed that there are certainly application windows for Cyrene. In the case of oxygenate extraction, a process with Cyrene appears energy-saving because the energy duty appears to be lower than when using water, the best alternative solvent, which is a low boiling solvent for this purpose.

Reactive extraction is an emerging operation in the industry, particularly in biorefining. Here, reactive extraction was demonstrated, enhanced by microwave irradiation to selectively heat the reactive phase (for efficient reaction) without unduly heating the extractive phase (for efficient extraction). These conditions aimed at maximizing the asymmetries in dielectric constants and volumes of the reaction and extraction phases, which resulted in an asymmetric thermal response of the two phases. The efficiency improvement was demonstrated by dehydrating xylose (5 wt % in water) to furfural with an optimal yield of approximately 80 mol % compared with 60–65 mol % under conventional biphasic conditions, which corresponds to approximately 50 % reduction of byproducts., It's not just a phase: Reactive extraction of xylose to furfural is boosted by a synergic combination of microwave heating and biphasic operation to deliver a hot aqueous phase for reaction and a colder organic phase for extraction.

In this work an all-electric regenerator is developed for the desorption of CO2 from air-capture sorbents using microwaves. An electromagnetic model was made for a continuous flow radial desorber and its dimensions were optimised for maximal microwave utilisation. Based on the optimal dimensions an actual prototype, capable of desorbing CO2 from a commercial supported amine sorbent in fixed- or moving-bed configuration was built to demonstrate the concept and to study performance characteristics. TSA experiments using nitrogen as purge gas to produce enriched air (1 to 2 vol.% CO2) were done. Productivities of up to 1.5 kg CO 2 / kg sorb . / d were demonstrated, with a total energy duty of 25 MJ / kg CO 2 . Compared to traditional TVSA desorption, the energy duty is similar while the productivity is significantly higher. The process can be further improved by creating an even more homogeneous electric field (preventing hot spots in the regenerator) and by enabling desorption under vacuum conditions to produce pure CO2. Overall, microwave desorption is demonstrated as an effective way to circumvent heat transfer limitations present during more traditional thermal desorption processes using polymeric sorbents.

Countercurrent membrane supported reactive extraction (MSRE) was studied for removal of carboxylic acids from aqueous streams with a PTFE capillary membrane. Analysis of the mass transfer rates was performed to support modeling of the process. Total mass transfer coefficients ranging from 2.0·10-7 to 4.0·10-7 m/s were obtained when extracting lactic acid with 20 wt% tri-N-octyl amine in 1-decanol with membrane thicknesses of 260 µm and 80 µm. The limiting mass transfer resistance in all experiments was in the membrane phase. The developed model based on mass transfer and reaction in parallel allows to predict countercurrent extraction. Experimental validation with 5, 7 and 12 m long membrane modules showed excellent accordance for two acids, validating the model simulations. Simulated membrane contactor lengths required for single, two and three countercurrent stages varied between 10 and 39 m/stage for lactic, mandelic, succinic, itaconic and citric acid, depending on acid, membrane, and diluent.

The pyrolytic conversion of methane for the production of hydrogen and carbon was investigated over nonporous α-Al2O3 surfaces in the range of 900–1300 ◦C. Two devices were used: i) a single particle reactor to determine the carbon deposition rate at various temperatures and ii) a fixed bed in which both methane conversion and carbon deposition were measured. It was observed that at 1000 ◦C and below, the selectivity towards carbon (and hydrogen) was initially low over fresh α-Al2O3 (e.g. 38% at 250 s reaction time), increasing to 100% over time. Methane conversion was constant at 20% during this period. These observations point towards the presence of an activation process for the formation of carbon and hydrogen from the intermediates products (e.g. benzene) of methane pyrolysis. A temperature dependent maximum in carbon loading was observed. When this maximum carbon loading was reached, methane conversion also stopped completely, indicating 100% selectivity towards carbon and hydrogen. Two kinetic models for carbon deposition were derived and applied. After parameterization of these models using single particle data, they were able to predict carbon growth and CH4 conversion as function of temper-ature, specific bed area, carbon loading and gas composition in the new data set from the fixed bed.

We present an easily accessible, open-access approach for fast pre-selection of solvents for extractive distillation at isobaric and isothermal conditions. The method uses the three-component Margules equation, which can predict vapor–liquid equilibria (VLE) in ternary systems with the infinite dilution activity coefficients, γi∞, as sole input parameters. This approach is accessible for anybody regardless of the availability of process simulators or other dedicated software to predict VLE, and can be combined with open access γi∞ to perform solvent screening. This approach shows a deviation in VLE of 10%. The presented method identifies molecular solvents for case studies where the same or similar solvents have also been reported in literature or are already applied on the industrial level, showing realistic pre-selection outcomes. Furthermore, small, cyclic, polar, molecular solvents are identified to induce preferential interactions and several structurally similar solvents, e.g. ethylene carbonate, dihydrolevoglucosenone and y-valerolactone, are identified to be potential alternative solvents. Among the ionic liquids (ILs) and deep eutectic solvents (DESs), the morpholinium and ammonium structures are identified to have the highest potential for increasing relative volatilities, they also show lower toxicity than other cations. This method thus proves to be able to perform early-stage pre-screening among new classes of solvents which generates information on the minimum required solvent to feed ratio (SFmin) for energy-efficient distillation from γi∞ obtained by measurement or from literature.

Lignocellulose is the most abundant source of saccharides and it is therefore a promising feedstock for glycols, such as ethylene-glycol, via catalytic hydrogenolysis of the polysaccharides that it contains. However, this catalytic hydrogenolysis step is hampered by the presence of lignin and other biomass contaminants, such as ash, which need to be removed in a pretreatment step. We propose an organosolv-like pre-treatment that can delignify and de-ash lignocellulose to a level that allows it to be upgraded to glycol with comparable yields to pure cellulose under demanding hydrogenolysis conditions. This work identifies the main design constraints of the integrated process and provides an initial experimental validation of it. Pretreatment of biomass in water/ethanol/acetic acid solutions at 180–200 °C can reduce the lignin content of the solid residue to ≤6 wt%. The addition of an organic acid, such as acetic acid, appears important to improve the removal of the recalcitrant Ca2+, which is a known inhibitor of the tungstate catalyst typically used in this process. The pretreatment medium is designed to use the by-product(s) of the process as organic solvent, to reduce the need for fresh solvent input. However, the process still needs a high solvent recovery (between 93.5 and 99.9 wt%). This can be achieved by selecting volatile component as organic solvent, as it allows recovery by evaporation from the dissolved lignin and ashes.

One of the EU’s strategies to combat climate change is the transition toward low-carbon energy technologies such as the transition to electric vehicles (EV’s). The accelerated introduction of EVs increases the demand for lithium-ion batteries (LIBs), where Cobalt (Co) supply is expected to be the bottleneck in their production. Co is one of the most critical raw materials on earth due to its rare existence and its near-monopolistic supply structure. Therefore, there is a growing incentive, if not critical need. for recycling Co from different waste sources such as industrial wastewater streams and spent LIB’s leachate. Although the process of Co retrieval plays an important role in replenishing Co stockpiles, it also contributes to reducing the environmental impact of industrial Co use and reducing the reliance on Co mining, during which the miners are exposed to highly hazardous conditions. Liquid-liquid extraction (LLX) is one of the most widely applied hydrometallurgical techniques for metal separation and recovery. This technology allows efficient processing of large volumes of aqueous solution in a continuous mode with relatively low capital and operational costs. At the beginning of the 21st century, a new type of solvents, known as ionic liquids (ILs), found their way to scientists as alternatives to the conventional volatile organic compounds (VOCs). These liquids, defined as salts which is in the liquid state at ambient temperatures or below 100 oC, have interesting properties such as a negligible vapor pressure, high thermal stability and a wide liquidus temperature range. In this PhD thesis, several aspects of process upscaling of an IL-based LLX system are considered. The goal is to investigate the application of an IL-based LLX process for the extraction and recovery of different transition metals (notably Co) from different process streams. In order to achieve this, fundamental research, experiments, modelling and a preliminary economic analysis are all included. It is decided to use tetraoctylphosphonium oleate [P8888][Oleate] as the solvent due to its unique selectivity towards transition metals. This makes it a good candidate for the extraction of Co from industrial wastewater and spent synthetic LIB leachate.

Tungstate-catalyzed hydrogenolysis of sugars in untreated woody biomass to ethylene glycol (EG) has so far been unsuccessful. This work shows that production of EG is predominantly hampered by the presence of inorganic impurities in the biomass, which can be selectively removed by an acid leaching step at room temperature. Catalytic hydrogenolysis of untreated and acid-leached samples of woody biomass was run at 245 °C using sodium polytungstate and Raney Ni catalysts at low loadings, which make them sensitive to deactivation by biomass impurities. Acid-leached pine and poplar samples gave a combined glycol yield (ethylene glycol + propylene glycol) of ∼44 wt %, similar to microcrystalline cellulose, whereas their untreated counterpart only delivered a yield of 22 wt %. Measurement of the dissolved fraction of the homogenous tungstate catalyst, i.e., active, after the experiment was found to be a key predictor of the EG yield: inorganic contaminants, such as calcium, are indeed shown to precipitate the tungstate catalyst.

This work focuses on the assessment of biobased solvents for the industrial separation of acetone and diisopropyl ether employing extractive distillation. From the experimental screening of 35 (biobased) solvents at 1000 mbar, 84/16 mol ratio acetone/ diisopropyl ether, and a solvent to feed ratio of 1 (mass based) it was observed that DL-limonene entrained diisopropyl ether, resulting in an acetone relative volatility of 1.44. This is a consequence of the selective repulsion of the low-boiling and more polar acetone by DL-limonene. More extensive vapor-liquid equilibrium (VLE) analysis over the entire acetone-diisopropyl ether (pseudo-)binary composition range showed that DL-limonene was the only biobased solvent able to break the azeotrope. The experimentally investigated VLE data of this ternary system was successfully correlated with the NRTL and UNIQUAC models. The other solvents that appeared most interesting in the initial screening were water and ethylene carbonate, entraining acetone with the highest observed diispropyl ether relative volatilities of 2.71 and 11.6. Although the high induced relative volatility for the 84/16 mol ratio acetone/ diisopropyl ether appeared interesting, over the entire composition range this resulted however in a shift in location of the azeotrope rather than removing the azeotrope. Therefore, it was concluded that DL-limonene is for this system the best performing biobased entrainer of the screening study. The observations are in agreement with observations from literature on similar systems, where oxygenated polar solvents were seen to have more affinity towards the ketone than towards the ether, while apolar solvents induce a higher volatility of the ketones.

BACKGROUND: Vapor–liquid and liquid–liquid equilibria of unsaturated and saturated hydrocarbons with the bio-based solvent dihydrolevoglucosenone, trademarked as Cyrene, have been reported recently, aiming at the utilization of the solvent in liquid–liquid extraction (LLX) and extractive distillation (ED). In this work, for a model system comprised of methylcyclohexane (MCH) and toluene (TOL), both LLX-based and ED-based processes were compared over a wide range of compositions based on simulations in AspenPlus V10. An economic evaluation based on total annual costs was performed, and the processes using Cyrene were compared with equivalent processes using the industrial benchmark Sulfolane. RESULTS: In the absence of literature data for Sulfolane–MCH–TOL, additional liquid–liquid extractions were done to facilitate parameter estimation for simulation. The Cyrene-based ED process was found to be more efficient than the Sulfolane-based ED process, primarily at lower (30 mol% the ED process with Cyrene is most economic. This process analysis showed that Cyrene is an appropriate bio-based alternative for Sulfolane as an entrainer for ED processes to separate aromatics and aliphatics.

A strategy for the design of a hydrogen supply chain (HSC) network in Germany incorporating the uncertainty in the hydrogen demand is proposed. Based on univariate sensitivity analysis, uncertainty in hydrogen demand has a very strong impact on the overall system costs. Therefore we consider a scenario tree for a stochastic mixed integer linear programming model that incorporates the uncertainty in the hydrogen demand. The model consists of two configurations, which are analyzed and compared to each other according to production types: water electrolysis versus steam methane reforming. Each configuration has a cost minimization target. The concept of value of stochastic solution (VSS) is used to evaluate the stochastic optimization results and compare them to their deterministic counterpart. The VSS of each configuration shows significant benefits of a stochastic optimization approach for the model presented in this study, corresponding up to 26% of infrastructure investments savings.

The chemical industry is currently facing the challenge of developing biobased production processes suitable for a more sustainable chemical industry. Acrylic acid produced from monopropylene glycol is a good candidate to become a cost-competitive and sustainable platform chemical. The propylene glycol price is expected to drop due to the expected abundance of propylene glycol as a sugar hydrogenolysis byproduct, which is required to make the conversion to acrylic acid cost-competitive. Two different processes for the conversion of propylene glycol to acrylic acid are evaluated in this work, either by (1) low temperature oxidation of propylene glycol to lactic acid and high temperature dehydration to acrylic acid or by (2) high temperature dehydration of propylene glycol to allyl alcohol and further high temperature oxidation to acrylic acid. Liquid-liquid extraction was found to be a key operation in both production processes. At similar overall yields, the allyl alcohol route appears inherently favored, as a result of the opportunity to integrate the reaction heat available at high temperature. To conclude, the price of propylene glycol has to drop by 45-55% to make the biobased production of acrylic acid from propylene glycol economically feasible.

The use of a wide range of bio-based solvents as entrainers in extractive distillation applications was investigated. The separation of hydrocarbon mixtures containing aromatic and aliphatic compounds is highly relevant, and the use of bio-based solvents for this separation was studied using the model system of methylcyclohexane and toluene. Additionally, the use of bio-based solvents for the difficult olefin/paraffin separation was studied using the model system of n-heptane and 1-heptene. From all of the bio-based solvents studied, Cyrene™ showed the highest relative volatility in the methylcyclohexane-toluene system. At compositions up to 40 wt% of methylcyclohexane in the hydrocarbon mixture, with a relative volatility of 3.17 ± 0.16 at 1000 mbar, the selectivity was comparable with the state-of-the-art industrial solvent Sulfolane™. At higher methylcyclohexane fractions, Cyrene™ outperforms Sulfolane™, resulting in a 43% reduction of the minimum reflux ratio, which is an excellent measure of energy efficiency. With regard to the relative volatility of n-heptane over 1-heptene, Cyrene™ also induces an increase in the relative volatility, but not as much as the industrial benchmark n-methylpyrrolidone (NMP). A relative volatility of 1.20 was measured at a solvent-to-feed ratio of 3 (mass basis), which can be further increased by the addition of extra Cyrene™. This leads to the prospect that Cyrene™ may be used for extractive distillation in olefin/paraffin separations, replacing NMP which is subject to severe environmental restrictions by the REACH agreement due to toxicity. This journal is

The role of choline chloride in biomass delignification by a deep eutectic solvent (DES) containing lactic acid was investigated. In this study, the influence of choline chloride on pulping of Eucalyptus globulus chips was determined. Pulping experiments were performed at 120 °C for 8 h with a DES to wood ratio of 20:1. Various experiments were performed to study the influence of choline chloride on lignin solubility, cleaving reactions, and mass transfer in order to gain an understanding of the observed pulping results. It was found that the chloride anion is the active component of choline chloride. In fact, the inexpensive salt NaCl performed as well as choline chloride in that respect. Furthermore, choline chloride is already effective in a 1:250 M ratio to lactic acid. Studies on milled wood lignin show that choline chloride increases the cleavage rate of β-O-4 and thereby increases the delignification rate of biomass. Furthermore, choline chloride slightly decreased the solubility of lignin in DESs and due to an increase in viscosity decreased the estimated mass transfer coefficient. Overall, the delignification rate of Eucalyptus by lactic acid increased by the addition of halide salts.

A novel condensing reactor for conversion of CO2 to methanol is characterized under forced convective conditions, both experimentally and by modeling. The goal of the study is to optimize the operation conditions and identify limitations of the reactor concept. Experimental results show that productivity is limited by reaction equilibrium and mass transport at high temperature (>250 °C), while reaction kinetics limit productivity at low temperature (

The NH4Cl-assisted dehydration of xylose to furfural was studied using traditional and microwave heating. Significant differences in rate, pH profiles, and selectivity profiles were observed between both heating systems. A comparative kinetic analysis showed 7-13 times higher first-order rate constants for the xylose dehydration reaction under microwave heating. Dedicated experiments with varying irradiation power and liquid mixing intensity suggested that the differences are due to the development of overheated areas under microwave heating. This hypothesis was supported by modeling the rate enhancement observed under microwave heating using a simple kinetic model that assumes a minor overheated fraction amid a bulk liquid at target temperature.

The earlier proposed two-step process, consisting of hydrogenation followed by hydrothermal gasification, for the conversion of carbohydrates is further developed by increasing its productivity, through the use of Pt and Ru catalysts in series. Aqueous sucrose is used as a model system to represent carbohydrate-rich waste water streams. In the first step, stabilisation, sucrose in a mass fraction of 10% in water is treated in a 45 cm 3 batch autoclave reactor with H 2 and is fully converted to sorbitol and mannitol at 413 K using a Ru catalyst with a 5% metal loading on a carbon support. A pseudo-first order kinetic model is developed and parameterised to support process development. In the second step, the stabilised mixture is gasified at 573 K using Pt and Ru catalysts with mass fractions of 5% on γ-Al 2 O 3 and carbon supports respectively. The novel sequential combination of these two catalysts for gasification provides high H 2 yields as well as high carbon to gas conversion (X CG ). The carbon based weight hour space velocity (WHSV c ) is increased from ca. 0.04 h −1 in previous work to 1 h −1 in this work. An energy balance shows that the ratio of the useable energy to the energy import, also termed ‘Energy Return On Energy Investment’ (EROEI) is ca. 5. This process provides an opportunity to simultaneously obtain clean water (TOC ∼ 4.7 g m −3 ) and produce valuable fuels (H 2 and CH 4 ) from carbohydrate-rich waste streams such as wastewaters from potato processing, fruit and vegetable processing industries.

BACKGROUND: Ethyl levulinate (EL) is an important chemical that can be used as a bio-based replacement of fuel additives such as methyl tert-butyl ether (MTBE) and tert-amyl methyl ether (TAME). EL production from lactic acid and ethanol is a viable option, as both precursors can be obtained from biomass. However, the problem of EL production by esterification is that this reaction is hindered by the chemical equilibrium limitations and the boiling points ranking, which is not the most favorable. RESULTS: This study provides novel optimally designed reactive distillation (RD) processes for the production of EL, taking into account costs, environmental impact and safety. The thermally coupled RD process is the most appealing, with the lowest energy use (1.667 MJ kg−1 EL), minimal investment cost, major energy savings (up to 54.3% lower than other RD processes), reduced environmental impact (up to 51% lower ECO99 index value) and similar safety as other RD processes considered (less than 2% differences in the individual risk (IR) indicator). CONCLUSION: The multi-objective optimization approach used here showed its robustness, practicality and flexibility to provide multiple optimal designs of intensified processes that are economically attractive, environmentally friendly and inherently safe.

A kinetic modeling study on long chain n-paraffin dehydrogenation using a commercial Pt-Sn-K-Mg/γ-Al 2 O 3 catalyst was carried out in a continuous flow set-up using n-dodecane as a model component at various temperatures (450-470 °C), pressures (0.17-0.30 MPa), H 2 /paraffin mole ratios (3:1-6:1) and space times (0.22-1.57 g h mol −1 ). The commercial catalyst was characterized by XRD, BET, MIP, SEM and CO chemisorption. An empirical exponential equation was found to predict the mono- and di-olefin yields very well. In addition, 6 mechanistic models based on the LHMW mechanism were derived and tested by non-linear least squares fitting of the experimental data. The model which assumes that surface reactions and particularly the dehydrogenation of the metal-alkyl chain to the adsorbed mono-olefin and di-olefin as the rate determining steps was found to give the best fit with the experimental data. In addition, activation energies and adsorption enthalpies for each elementary reaction were obtained. The kinetic testing and modeling have shown that the high mono-olefins selectivity for long chain paraffin dehydrogenation can be obtained by operating at low space time (when P, T and m are same), high pressure (when τ, T and m are same) and high H 2 /paraffin ratio (when τ, P and T are same), as well as low reaction temperature (when τ, P and m are same) but with little effect.

This communication evaluates the suitability of gas and liquid chromatography for the quantification of levoglucosan and hydroxyacetaldehyde in bio-oils. It was found that both techniques can principally determine levoglucosan quantitatively in cellulose/biomass derived bio-oils. However, it is also shown that oligo-anhydrosugars present in the bio-oils undergo depolymerisation to levoglucosan during gas chromatography, resulting in an overestimation of the concentration of levoglucosan. Hydroxyacetaldehyde can only be determined quantitatively by liquid chromatography. Presented experimental evidence shows that the high temperature (200–320 °C) of injection in gas chromatography is a key factor causing oligo-anhydrosugars and hydroxyacetaldehyde to react during analysis, which may lead to flawed results.

The infinite dilution activity coefficient (γi∞) is often applied to characterize solvent−solute interactions, and, when accurately predicted, it can also serve as an early-stage solvent selection tool. Ample data are available on the use of a variety of models, which complicates decision making on which model to apply and when to apply it. A comparative study was performed for eight predictive models at 298.15 K, including the Hildebrand parameter and the Hansen solubility parameters. Also, three group contribution methods based on UNIFAC, COSMO-RS, the Abraham model, and the MOSCED model were evaluated. Overall, the MOSCED model and the Abraham model are most accurate for molecular solvents and ionic liquids, respectively, with average relative deviations of 16.2% ± 1.35% and 65.1% ± 4.50%. Therefore, cautious decision making based on predicted γi ∞ in ionic liquids should always be done, because of the expected significant deviations. A MOSCED model for ionic liquids could be a potential approach for higher accuracy.

Isothermal Titration Calorimetry (ITC) and molecular modeling (MM) were combined with liquid-liquid equilibrium data to obtain better understanding of solvent effects on complexation in reactive liquid–liquid extraction. Two examples with ample extraction literature available were studied, acetic acid extraction and phenol extraction. Interactions with binary solvents were studied. Based on the insight and quantification of complexation with MM and ITC, models describing the liquid-liquid equilibrium (LLE) were formulated and validated with experiments, showing that ITC can predict LLE. ITC together with MM indeed can yield additional insight in complexation behavior in reactive liquid–liquid extraction and may guide solvent selection procedures.

This article is meant to frame the challenges and opportunities of the methane conversion to methanol via a chemical looping (or redox) process by comparison with the industrial performance criteria. Accordingly, the low methanol productivity and the expected long cycle time result in an overall production rate that falls a factor of ∼50 below the industrial threshold and leads to the prohibitive material cost. With this analysis, we aim to stimulate the diversification of the research directions toward making the process more economically interesting. We also extend this analysis to a variety of the chemical looping processes and conclude that they all fall short of the simple productivity criteria. We therefore recommend researchers pay more attention to improving productivity in these processes.

Production of volatile fatty acids (VFAs) by fermentation is a potential sustainable alternative for conventional petrochemical routes to VFAs. Due to the low VFA content of fermentation broths, robust and economical separation technology has to be devised to recover the VFA. Liquid-liquid extraction of VFAs with the phosphonium phosphinate ionic liquid (IL) [P 666,14 ][Phos] allows good VFA extractability. For an extraction process using [P 666,14 ][Phos] to be green, it is essential to efficiently regenerate the solvent and recover the VFA. To obtain insight into the (strong) intermolecular interactions between [P 666,14 ][Phos] and acetic acid, selected as a model VFA, 1 H NMR, 31 P NMR, FT-IR and isothermal titration calorimetry (ITC) were applied. The observations were used to interpret operations to recover acetic acid from the IL, which included evaporation at elevated temperature under vacuum, possibly assisted by nitrogen stripping, in situ esterification and back-extraction with volatile bases. Through evaporative regeneration with nitrogen stripping, HAc could be removed, but only down to an HAc/IL molar ratio of 1. The remaining molar equivalent of HAc-IL interacts tightly with the IL by partial proton transfer and strong hydrogen bonding interactions with the phosphinate anion. Back-extraction of HAc with trimethylamine (TMA) and subsequent decomposition of the HAc-TMA complexes allowed for successful IL regeneration. This process uses ten times less amine (TMA) than conventional amine-based extraction processes (e.g. tri-n-octyl amine), and provides a sustainable process route to obtain pure carboxylic acids from highly diluted aqueous solutions without generating large streams of byproducts. Further valorization via in-line vaporization/catalytic ketonization or via in-line thermal decomposition and ketonization of the TMA-HAc salt was also demonstrated, showing the potential of the VFAs as a green platform for bio-based chemicals.

Solvent selection is key in extractive distillation process development and solvent effects are often predicted based on the activity coefficients at infinite dilution. For close-boiling polar systems with strong or specific interacting species, standard simulation tools, e.g. using UNIFAC or COSMO-RS, often predict poor as the activity coefficients at infinite dilution not always reflect the selectivity in the process. For these systems, a heuristic solvent selection method in which molecular properties such as acidity, hydrogen bonding and polarity are applied is desired as first estimate in the solvent selection. To explore the key parameters for such a first selection, solvent effects on the relative volatility ( α ) were measured for three different industrially relevant polar mixtures, valeric acid – 2-methylbutyric acid, diethylmethylamine – diisopropylether, and 2-butanol – 2-butanone. For each of the cases the effect of potential solvents on α was measured in an ebulliometer. For the acids, the difference in p K a of 0.1 was too small to separate based on acidity with a moderately basic solvent. Stronger basic solvents resulted in thermal and chemical instability. Although the solvent methyl-2-methyl butyrate is not suitable as a solvent because of reactivity, this structurally similar solvent showed selectivity, indicating also in extractive distillation the like dissolves like phenomenon can be applied to induce selectivity. A larger difference in basicity of the mixture components (amine–ether mixture) and a difference in hydrogen bonding affinity between the mixture components (ketone–alcohol mixture) allowed for increasing α based on differences in acidity and hydrogen bonding, respectively.

Lignins with number average molecular weights between 350 Da and 1900 Da were characterised and subsequently pyrolysed in a screen-heater at pressures of 500 Pa and 105 Pa between 425 °C and 793 °C. Upwards of 530 °C, the temperature turned out to have only a minor influence on the yields and composition of the oils produced. Clear trends were observed as a function of the molecular weight and pressure – (1) at increasing molecular weight of the lignin, the oil yield decreases while yields of char and gas increase, (2) the molecular weight of the oil is lower for oils produced at 105 Pa as compared to the ones obtained at 500 Pa, (3) above a certain molecular weight of the lignins, ∼400 Da for 105 Pa and ∼800 Da for 500 Pa, the molecular weight of the oil becomes independent of the molecular weight of the lignin. A mathematical model has been developed, which includes three concurrently occurring processes, viz. cracking and polymerisation reactions and removal, hence mass transport, of unconverted lignin and reaction products from the reaction zone. This model can describe all the trends observed experimentally and provides, after parametrisation, reasonable qualitative predictions of the yield and molecular weight of the oils. Knowledge of the role of the interplay between mass transport and chemistry in the pyrolysis process is further accumulating, and from this the development of lignin valorisation can avail. For instance, it has become clear that in the pyrolysis process the molecular weight of lignin oil, which is an important characteristic for the upgrading of the oil to chemicals and/or fuels, can be steered with the pressure.

Using both experiments and modelling, hydrothermal gasification of sorbitol (SB) aiming at maximal carbon to gas conversion and H2 production was investigated over a wide temperature range (270–350 °C). Kinetics were studied in a continuous tubular reactor using a Pt/γ-Al2O3 catalyst. The addition of N2, resulting in lower H2 concentrations in the liquid phase, was found to have a beneficial effect in terms of higher H2 yield without compromising on the carbon gasification. The highest H2 yield obtained in this work was 4 mol H2/mol SB. Existing reaction schemes for sorbitol gasification were used to derive a path-lumped scheme. A multi-phase reactor model including a path-lumped scheme and gas-liquid-solid mass transfer was developed and parameterized based on datasets with varying temperature, space velocity, inlet gas composition (N2 or H2) and gas-liquid flow ratio. The developed model was used to provide guidelines for the design of an industrial reactor for the gasification of 10 tons/h of 10 wt% aqueous sorbitol. The effect of N2 stripping and industrially attainable kLa values were found to boost the H2 yield from 4 to 12 mol H2/mol SB making it an attractive process for further consideration.

Biogas is a significant by-product produced in algae processing and may be used for many different applications, not only as a renewable energy carrier but also as a chemical intermediate in integrated algae-based biorefineries. In this work, the reforming of biogas to H2/CO2 mixtures (referred to as SynFeed) as feed for the direct hydrogenation of CO2 to methanol is investigated. Two conventional processes, namely steam methane and autothermal reforming, with upstream CO2 separation from raw biogas are compared to novel concepts of direct biogas bi- and tri-reforming. In addition, downstream CO2 separation from SynFeed using the commercial Selexol process to produce pure H2 and CO2 is considered. The results show that upstream CO2 separation with subsequent steam methane reforming is the most economic process, costing 142.48 €/tSynFeed, and taking into consideration the revenue from excess hydrogen. Bi-reforming is the most expensive process, with a cost of 413.44 €/tSynFeed, due to the high demand of raw biogas input. Overall, SynFeed from biogas is more economical than SynFeed from CO2 capture and water electrolysis (464 €/tSynFeed), but is slightly more expensive than using natural gas as an input (107 €/SynFeed). Carbon capture using Selexol comes with costs of 22.58–27.19 €/tCO2, where approximately 50% of the costs are derived from the final CO2 compression.

Ammonia may be one of the energy carriers in the hydrogen economy. Although research has mostly focused on electrochemical ammonia synthesis, this however remains a scientific challenge. In the current article, we discuss the feasibility of single-pass thermochemical ammonia synthesis as an alternative to the high-temperature, high-pressure Haber-Bosch synthesis loop. We provide an overview of recently developed low temperature ammonia synthesis catalysts, as well as an overview of solid ammonia sorbents. We show that the low temperature, low pressure single-pass ammonia synthesis process can produce ammonia at a lower cost than the Haber-Bosch synthesis loop for small-scale ammonia synthesis (

Pulsed compression is introduced for the conversion of methane, by pyrolysis, into ethylene. At the point of maximal compression temperatures of 900 to 1620 K were reached, while the initial and final temperature of the gas did not exceed 523 K. By the use of a free piston reactor concept pressures of up to 460 bar were measured with nitrogen as a diluting gas. From 1100 K onwards methane conversion was measured. By increasing the temperature, the mechanism of pyrolytic methane conversion, being subsequent production of ethane, ethylene, acetylene, …, benzene, and ultimately tar/soot, was clearly observed. Without hydrogen in the feed, the attainable operating window (C2-selectivity vs. methane conversion) observed was similar to other catalytic oxidative and non-oxidative coupling processes. With hydrogen, in a first attempt to optimize the product yield, 24% C2-yield (62% ethylene selectivity, 93% C2-selectivity) at 26% conversion was reached without producing observable soot. It is worthwhile to explore pulsed compression further because it does not require a catalyst and therefore, does not deactivate over time and it operates at low reactor temperature.

The increasing need for sustainable processes stimulates the production and recovery of renewable organic acids. The purification of these acids is often difficult because of similar acid volatilities but can be improved through extractive distillation. Generic insights into solvent effects on the separation efficiency for close-boiling acids are however lacking. This study provides insights into the effect of acidity, the acidity difference between the acids, the hydrogen-bonding strength of the solvent, and the solvent-to-feed ratio on organic acid separation efficiency. For an acetic acid-formic acid (AA-FA) mixture, the addition of high-boiling organic acids increases the relative volatility of FA over AA significantly. The addition of a Lewis base reverses the relative volatility, which depends on the applied solvent-to-feed ratio and the Lewis base BF3 affinity. For several binary acid mixtures (such as AA-FA and monochloroacetic acid-dichloroacetic acid), where the acids have a relatively big difference in acidity (ΔpKa ≥ 1), the separation selectivity appears practically independent of the acid strength of the individual acids and increases with increasing BF3 affinity of the Lewis base. For acid mixtures with a lower ΔpKa, a lower separation selectivity is obtained, as observed for separation of the pivalic acid-butyric acid and valeric acid-2-methyl butyric acid mixtures. When one of the acids in the mixture contains a secondary ketone group (i.e., levulinic acid in a levulinic acid-octanoic acid mixture), the strongest acid based on pKa is not necessarily attracted most by the added Lewis base. This, at first sight, unexpected behavior is most likely the result of complex intra- and intermolecular interactions and is quantitatively in line with COSMO-RS-based selectivity predictions.

The solid–liquid equilibrium (SLE) behavior and liquid–liquid extraction (LLX) abilities of deep eutectic solvents (DESs) containing (a) thymol and L-menthol, and (b) trioctylphosphine oxide (TOPO) and L-menthol were evaluated. The distribution coefficients (KD) were determined for the solutes relevant for two biorefinery cases, including formic acid, levulinic acid, furfural, acetic acid, propionic acid, butyric acid, and L-lactic acid. Overall, for both cases, an increasing KD was observed for both DESs for acids increasing in size and thus hydrophobicity. Furfural, being the most hydrophobic, was seen to extract the highest KD (for DES (a) 14.2 ± 2.2 and (b) 4.1 ± 0.3), and the KD of lactic acid was small, independent of the DESs (DES (a) 0.5 ± 0.07 and DES (b) 0.4 ± 0.05). The KD of the acids for the TOPO and L-menthol DES were in similar ranges as for traditional TOPO-containing composite solvents, while for the thymol/L-menthol DES, in the absence of the Lewis base functionality, a smaller KD was observed. The selectivity of formic acid and levulinic acid separation was different for the two DESs investigated because of the acid–base interaction of the phosphine group. The thymol and L-menthol DES was selective towards levulinic acid (Sij = 9.3 +/− 0.10, and the TOPO and L-menthol DES was selective towards FA (Sij = 2.1 +/− 0.28).

This dissertation will focus on creating specific separation processes, called Solvent-based Affinity Processes, in which not only the energy requirements will be lower than current state-of-the-art processes, but also evaluate the use of sustainable solvents which can be produced from sustainable resources. The search towards alternative, better functioning, solvents is therefore not a new research topic and has been done for many decades. In Chapter 3, we compiled and visualized a comprehensive database of infinite diluted activity coefficients (γ∞) which is a highly specific parameter that describes interactions between the solute and solvent. Chapter 4 describes a methodology using the 3-component Margules equation to extend the applicability of the γ∞ towards realistic solvent to feed ratios, or in other words, finite concentrations. Chapter 5 assesses the possibility of predicting these γ∞ by using eight theoretical models, while Chapter 6 attempts to correlate γ from solely heat of mixing experiments via thermodynamic models which allows for the prediction of isobaric vapor-liquid equilibria. In Chapters 7 and 8, we screen biobased solvents, for the extractive distillation of resp. apolar and polar mixtures, while Chapter 9 extends this investigation into liquid-liquid extractions using a promising biobased solvent named dihydrolevoglucosenone (Cyrene). Chapter 10, combines all earlier experiments into rigorous process simulations to investigate the potential of Cyrene in the separation of an apolar mixture.

Lignocellulosic biomass is the most abundantly available sustainable raw material on earth. Replacing fossil feedstocks for the chemical industry, such as oil, coal and natural gas by biomass can reduce the CO2 emissions of the chemical industry. However, the availability of lignocellulosic biomass is limited. Therefore, it is key to use this feedstock as efficiently as possible. The current benchmark process in biomass fractionation is the kraft process. In this process, biomass is delignified using a solution of sodium hydroxide and sodium sulfide and the produced cellulose pulp is mostly used for papermaking. However, only half of the raw material is converted into cellulose pulp, the rest of the material is combusted for the generation of heat and for the recovery of sodium sulfide. Processes that can convert biomass in multiple products, including next to cellulose, also lignin and/or furans, are required to reduce global CO2 emissions. Deep eutectic solvents (DES) are composite solvents that exhibit deep eutectic behavior upon mixing. These solvents have shown great potential for biomass delignification and have the potential to produce not only cellulose pulp, but also other valuable byproducts, such as lignin and furans. Therefore, DES based processes can make more efficient use of the biomass feedstock than the kraft process. However, there are a couple of issues that need to be resolved before DES delignification processes can be applied on a large scale. First, the advantages of the combination of DES constituents are poorly understood. Second, the known methods for the recovery of lignin from DES are mostly applicable for laboratory purposes. Laboratory unit operations are not always applicable on industrial scale, and research is needed to better understand the pulping process, as well as solvent recovery operations. These issues are addressed in this thesis, after which a conceptual process is designed for the delignification of Eucalyptus globulus using a DES comprised of lactic acid and choline chloride. Original promotion date was July 3, 2020 (COVID-19)

After biomass fractionation using deep eutectic solvents (DES), solvent recovery is an essential step. Recovery of lignin from DES by liquid–liquid extraction (LLX) may provide large energy savings compared to cold water precipitation. Lignin that is dissolved in DES from biomass fractionation is inhomogeneous, meaning it has various fractions with different molar weights and possibly variations in functional group densities. Therefore, it is important to compare recoverability of every lignin fraction by LLX with cold-water precipitation. In this work, the recovery of lignin from a DES comprised of 30 wt% choline chloride and 70 wt% lactic acid was studied. Using as much as 30 wt% choline chloride is beneficial to limit leaching of lactic acid. Three cross-current extractions were performed using 2-MTHF. This method recovered 95% of the lignin fractions around 2000 g/mol and 85% of the lignin fractions around 10,000 g/mol. No inter-aromatic ether bonds were found in the lignin remaining in the DES raffinate by heteronuclear single quantum coherence spectroscopy (HSQC), indicating the remaining lignin in the DES has a highly condensed nature. Cold water precipitation could fully recover the lignin fractions above 4000 g/mol using 3.5 kg water per kg DES. However, only half of the lignin fraction of 1000 g/mol was recovered. Briefly, LLX is more suitable for the recovery of low molar weight fractions, while cold water precipitation is more suitable for the heavy molar weight fractions. For industrial applications, a combination of both approaches is essential for full lignin recovery.

A separation method to selectively recover valuable metals (Co, Ni, Mn and Li) from synthetic spent lithium-ion battery cathodes leachate using a fatty-acid-based ionic liquid, tetraoctylphosphonium oleate [P₈₈₈₈][oleate] is demonstrated. The investigated parameters for this selective separation and recovery process include extraction pH, contact time and composition of the regeneration solution. The benefit of using this ionic liquid is that >99% of Co and >99% of the Mn can be separated from the Ni and the Li by a two-stage extraction process. A subsequent single regeneration process separates the Co from the Mn. Finally, Ni and Li are completely separated in an additional regeneration process. An economic potential analysis concludes the paper, revealing that given the current cobalt price, the process outlined here shows a positive zero-order Economic Potential (bases on product sales and raw material cost) when using a 4 M HCl leaching solution and for leachates containing at least 4.5 g Co per liter.

The bioaqueous phase generated during biomass conversion to biofuel and biochemicals, e.g., fast pyrolysis and ex situ catalytic pyrolysis, contains a large number of organics, leading to a high chemical oxygen demand (COD) for its treatment. In this study, we demonstrate its catalytic conversion to bioacetic acid solution and propose a recycling strategy thereof. We found that the diluted bioaqueous phase (e.g., C content 90%) converted to acetic acid with nondetectable impurities in solution. The solution contains 1.3-1.5 wt % acetic acid and can be directly used for demineralization of biomass in the biorefineries. This recycling strategy enhances the sustainability of the biobased economy and sheds light on production of biobased acetic acid, which has been recognized as a smart drop-in chemical.