Lactic Acid Extraction and Mass Transfer Characteristics in Slug Flow Capillary Microreactors

Capillary microreactors operated under the slug flow regime were investigated for the separation of lactic acid from the aqueous phase using liquid–liquid reactive extraction. The experiments were performed at a 1:1 flow ratio of the aqueous to organic phases in a setup consisting of an inlet Y-type mixer connected with a poly(tetrafluoroethylene) capillary microreactor and subsequently an outlet Y-shape phase splitter. The extraction of lactic acid (intake: 0.11 and 0.055 M in water) using 15% (v/v) tri-n-octylamine in n-octanol under ambient conditions approached equilibrium after about 90 s in microreactors without noticeable emulsion formation. The measured reactive extraction performance in microreactors can be well described by a physical mass transfer model according to the penetration theory (developed from a model experimental study for the extraction of acetanilide from water to n-octanol) combined with an instantaneous irreversible reaction assumption

A Hierarchical Hybrid Method for Screening Ionic Liquid Solvents for Extractions Exemplified by the Extractive Desulfurization Process

A hierarchical hybrid method combining experimental-database-derived estimation of extraction performance, quantitative structure-property relationship (QSPR)-based assessment of IL physical and environmental properties, liquid-liquid extraction (LLE) measurement, and process evaluation is proposed to screen practically suitable ionic liquid (IL) solvents for different extractions. From the literature, 47 424 infinite dilution activity coefficient (IDAC) data including 12 IL families (e.g., imidazolium, pyridinium, ammonium, etc.) and 13 organic families (e.g., alkanes, aromatics, alcohols, etc.) are collected. On the basis of the IDAC data, the extraction performance of ILs for a specific separation can be estimated in terms of the distribution ratio and selectivity at infinite dilution. The ILs with potentially high extraction performance and meeting the physical and environmental properties criteria are selected to perform LLE experiments. Subsequently, process simulation and evaluation using the selected IL solvents are performed by Aspen Plus. To exemplify the proposed method, the extractive desulfurization (EDS) process is taken as a case study, where [EMIM][MESO3] (1-ethyl-3-methylimidazolium methanesulfonate) and [EIM][NO3] (1-ethylimidazolium nitrate) are selected after IDAC database searching and QSPR analysis. Experimental LLE with the two ILs are determined, demonstrating their promising extraction performance with the maximum selectivity (S-23(max)) for thiophene/heptane of 420 and 281.9, respectively. By fitting the NRTL model correspondingly, two processes using the screened ILs and sulfolane are developed and compared using Aspen Plus. It turns out that the two ILs save 66% and 48% in solvent requirements and 54% and 55% in energy consumption compared to those of sulfolane for the EDS task, respectively

Process Intensification of Enzymatic Fatty Acid Butyl Ester Synthesis Using a Continuous Centrifugal Contactor Separator

Fatty acid butyl esters were synthesized from sunflower oil with 1-butanol using a homogeneous Rhizomucor miehei lipase in a biphasic organic (triglyceride, 1-butanol, hexane)– water (with enzyme) system in a continuous setup consisting of a cascade of a stirred tank reactor and a continuous centrifugal contactor separator (CCCS), the latter being used for integrated reaction and liquid–liquid separation. A fatty acid butyl ester yield up to 93% was obtained in the cascade when operated in a once-through mode. The cascade was run for 8 h without operational issues. Enzyme recycling was studied by reintroduction of the water phase from the CCCS outlet to the stirred tank reactor. Product yield decreased over time to an average of 50% of the initial value, likely due to accumulation of 1-butanol in water phase, loss of enzyme due to agglomeration, and the formation of a separate enzyme layer

5-Hydroxy-2-Methylfurfural from Sugar Beet Thick Juice:Kinetic and Modeling Studies

5-Hydroxy-2-methylfurfural (HMF) has a high derivatization potential and is considered the sleeping giant of biobased platform chemicals. It is accessible by the acid hydrolysis of various carbohydrate-containing feeds, preferably those high in fructose content. We here report a detailed study on the use of thick juice, an intermediate sucrose (SUC)-rich stream in a sugar factory, and pure SUC for the synthesis of HMF in a batch reactor setup [in the presence of water and sulfuric acid (0.01 M) and at 180 °C]. Distinct differences in reactivity were found for both feeds, related to the presence of impurities (i.e., organic acids and salts) in the thick juice. To better understand the effect of the thick juice impurities, detailed model studies were performed involving the use of a model solution of SUC spiked with one of the thick juice impurities (organic acids such as maleic acid and a range of salts with potassium, sodium, calcium, and magnesium as the cations and carbonates, chlorides, and sulfates as the anions). The data were successfully modeled using a kinetic model for the main reactions in the network. The developed model revealed that sulfate anions have a major effect on the HMF yield and the batch time required to reach its optimum and are the likely cause of the differences in reactivity between pure SUC and thick juice

Advantages of Producing Aromatics from Propene over Ethene Using Zeolite-Based Catalysts

Sustainable production of aromatics, especially benzene, toluene and xylenes (BTX), is essential considering their broad applications and the current global transition away from crude oil utilization. Aromatization of lower olefins, particularly ethene and propene, offers great potential if they are derived from more circular alternative carbon feedstocks such as biomass and waste plastics. This work aims to identify the preferred olefin feed, ethene or propene, for BTX production in a fixed-bed reactor. A commercial H-ZSM-5 (Si/Al = 23) catalyst was used as a reference catalyst, as well as a Ga-ZSM-5 catalyst, prepared by Ga ion-exchange of the H-ZSM-5 catalyst. At 773 K, 1 bar, 45 vol % olefin, 6.75 h(-1), propene aromatization over the Ga-ZSM-5 catalyst exhibited higher BTX selectivity of 55 % and resulted in slower catalyst deactivation compared to ethene aromatization

Diels-Alder-based thermo-reversibly crosslinked polymers:Interplay of crosslinking density, network mobility, kinetics and stereoisomerism

Polymers crosslinked through thermo-reversible furan/maleimide Diels-Alder chemistry have been widely explored, since they stand as an ingenious design for reprocessable and self-healing thermosets and elastomers. For these polymeric products, crosslinking density plays a key role on the polymer thermo-reversibility. However, how this degree of network interconnectivity influences the kinetics of thermal reversibility has not yet been addressed. In order to tackle this problem, furan-grafted polyketones crosslinked by a bi-functional maleimide were prepared with different ratios between maleimide and furan groups. The thermo-reversible dynamics of the prepared polymers were then studied by rheology and differential scanning calorimetry. Here we show that, the thermo-reversible process occurs faster and at lower temperatures in polymers with lower crosslinking densities. Network mobility is responsible for this effect. It allows the formulations to rearrange their polymer network differently through the heating-cooling cycles. The results also indicate that the crosslinking density rather than the stereoisomerism of the Diels-Alder adducts plays a larger role in the reversible behavior of the system. Additionally, the thermo-reversible features of the polymer were shown to be dependent on its thermal history. This work impacts the development of reprocessable and self-healing crosslinked polymers, and the design of the corresponding reprocessing and healing procedures

Chemical Equilibria in Methanol Synthesis Including the Water–Gas Shift Reaction:A Critical Reassessment

A large number of experimental equilibrium constants for the reactions involved in methanol synthesis were collected or calculated from several literature sources. Equilibrium relationships were derived from basic thermochemical data and subsequently fitted to the experimental results by adapting only the Gibbs energy of formation values for CH3OH and CO. Very small changes of these parameters as compared to the original literature values were sufficient to obtain accurate relationships that adequately describe the experimental results

Lactic Acid Extraction and Mass Transfer Characteristics in Slug Flow Capillary Microreactors

Capillary microreactors operated under the slug flow regime were investigated for the separation of lactic acid from the aqueous phase using liquid–liquid reactive extraction. The experiments were performed at a 1:1 flow ratio of the aqueous to organic phases in a setup consisting of an inlet Y-type mixer connected with a poly(tetrafluoroethylene) capillary microreactor and subsequently an outlet Y-shape phase splitter. The extraction of lactic acid (intake: 0.11 and 0.055 M in water) using 15% (v/v) tri-n-octylamine in n-octanol under ambient conditions approached equilibrium after about 90 s in microreactors without noticeable emulsion formation. The measured reactive extraction performance in microreactors can be well described by a physical mass transfer model according to the penetration theory (developed from a model experimental study for the extraction of acetanilide from water to n-octanol) combined with an instantaneous irreversible reaction assumption

Support screening studies on the hydrogenation of levulinic acid to γ‐valerolactone in water using RU catalysts

γ-Valerolactone (GVL) has been identified as a sustainable platform chemical for the production of carbon-based chemicals. Here we report a screening study on the hydrogenation of levulinic acid (LA) to GVL in water using a wide range of ruthenium supported catalysts in a batch set-up (1 wt. % Ru, 90 °C, 45 bar of H2, 2 wt. % catalyst on LA). Eight monometallic catalysts were tested on carbon based(C, carbon nanotubes (CNT)) and inorganic supports (Al2O3, SiO2, TiO2, ZrO2, Nb2O5 and Beta-12.5). The best result was found for Ru/Beta-12.5 with almost quantitative LA conversion (94%) and 66% of GVL yield after 2 h reaction. The remaining product was 4-hydroxypentanoic acid (4-HPA). Catalytic activity for a bimetallic RuPd/TiO2 catalyst was by far lower than for the monometallic Ru catalyst (9% conversion after 2 h). The effects of relevant catalyst properties (average Ru nanoparticle size, Brunauer-Emmett-Teller (BET) surface area, micropore area and total acidity) on catalyst activity were assessed