Biphasic Reactor Research Articles

Clarifying solvent effect during photocatalytic glycerol conversion on TiO2/GQD as selective photocatalyst

Nowadays, dealing with the growing chemical and energy demands is important without compromising the environment. So, this work studies photocatalytic glycerol conversion (as biomass derivativ feedstock) into value-added products using an eco-friendly synthesized catalyst. Graphene quantum dots (GQDs) were prepared from available/cheap precursors like glucose via the hydrothermal method and used as a support for TiO2. TiO2/GQDs were characterized via different analytical techniques, revealing very small particle sizes of ~ 3–6 nm with a large surface area of ~ 253 m2/g and a band gap of ~ 2.6 eV. The prepared photocatalyst shows good efficiency during photocatalytic glycerol conversion to dihydroxyacetone (DHA). Different reaction conditions were tested: reaction time, catalyst amount, presence of oxidant (H2O2), and biphasic media (aqueous/organic phases). Comparing a monophasic (H2O) photoreactor with a biphasic reactor containing 90% organic phase (ethyl acetate) and 10% aqueous phase (H2O and/or H2O2) indicates that the presence of H2O2 increases glycerol conversion and liquid selectivity to reach 57% and 91%, respectively after 120 min. However, it still suffers a low DHA/GA ratio (2.7). On the other hand, using a biphasic reactor in the presence of an H2O2 oxidant increases the DHA/GA ratio to ~ 6.6, which was not reached in previous research. The formation of H2O/H2O2 as micro-reactors dispersed in the ethyl acetate phase increased the average light intensity effect of the glycerol/photocatalyst system in the micro-reactors. Unlike previous work, this work presents a facile way to prepare eco-friendly/cheap (noble metal free) photocatalysts for glycerol conversion to ultrapure DHA using a biphasic photoreactor.

Sustainable Production of Furfural in Biphasic Reactors Using Terpenoids and Hydrophobic Eutectic Solvents

Furfural comes from lignocellulosic biomass that, together with its derived products, has many useful applications in several industries. Furfural is usually obtained via pentose dehydration using a biphasic reactor to extract furfural in situ from its reaction medium. However, the conventional solvents used so far, mainly toluene and methyl isobutyl ketone (MIBK), are harmful to health and the environment. Therefore, hydrophobic natural solvents have been successfully tested in this work to improve the performance of the process from a sustainable point of view. First, 30 natural solvents were screened using the conductor-like screening model for real solvents (COSMO-RS) method to select solvents with high affinity to furfural. From the results obtained in the screening, 14 natural and 2 conventional solvents were selected for experimentation, including thymol, eugenol, toluene, MIBK, and several hydrophobic eutectic solvents formed by thymol. Then, the liquid–liquid extraction of furfural was carried out both in vials and in a reactor, simulating the usual temperature and pH conditions for obtaining furfural. Thymol and eugenol showed extraction yields of 95 and 91%, significantly higher than those of conventional solvents MIBK and toluene, which were 85 and 81%, respectively. Finally, the in situ reaction and extraction of furfural from xylose were performed using the natural solvents eugenol and thymol and the conventional solvent MIBK. Under operating conditions, namely, microwave heating to 443.2 K, 10 min of reaction, and a solvent-to-feed ratio of 1.00, xylose conversion of 96.7%, furfural selectivity of 75.3%, and a furfural production yield of 72.8% from xylose were obtained using eugenol as the organic solvent, with improved outcomes over MIBK and thymol cases, pointing an adequate approach to improve both the effectiveness and the sustainability of the process.

Hydrodynamics and mass transfer investigations in a biphasic plasma reactor

Abstract This work aims to investigate the radical mechanism responsible for the degradation of a highly soluble pollutant in water. The AG25 dye was chosen as substrate and the GAD-Spray as biphasic reactor to treat it remotely. The study is conducted through experiments and simulations using Comsol Multiphysics-chemical engineering module. The Hydrodynamics coupled with the plasma-reaction has demonstrated that a low mass transfer in the droplet favorites the removal of the pollutant. It indicates that the plasma-reactions take place at the stagnant liquid film are far from the bulk of the droplet. Numerical modeling fitted by the conversion rate of the reagent has shown that the peroxynitrous acid HOONO (PON) is responsible for the degradation of AG25 in water. Consequently, and according different kinetic mechanisms, a radical mechanism has been predicted based on this deduction. The removal and the degradation rates were of 88 and 83% respectively during 90 min after the plasma exposure. The results of simulations showed a significant agreement between the calculated and the real removal rate of AG25. Through this study, it can be confirmed that GAD-spray-tower plasma reactor is efficient to eliminate and degrade remotely a very soluble pollutant through the HOONO (PON) plasma long-lived species.

Biodesulfurization of refractory sulfur compounds in petro-diesel by a novel hydrocarbon tolerable strain Paenibacillus glucanolyticus HN4.

One of the main precursors of air pollution and acid rains is the presence of the recalcitrant thiophenic compounds, for example dibenzothiophene (DBT) and its derivatives in transportation fuels. In an attempt to achieve the worldwide regulations of ultra-low sulfur transportation fuels without affecting its hydrocarbon skeleton, a biphasic medium containing 100 mg/L DBT dissolved in n-hexadecane (1/4 oil/water v/v) used for enrichment and isolation of selective biodesulfurizing bacterium from an oil-polluted sediment sample collected from Egyptian Red Sea shoreline. The isolated bacterium is facultative anaerobe, motile, spore-former, and mesophile. It is genetically identified as Paenibacillus glucanolyticus strain HN4 (NCBI Gene Bank Accession No. MT645230). HN4 desulfurized DBT as a model of the recalcitrant thiophenic compounds without affecting its hydrocarbon skeleton via the 4S-pathway producing 2-hydroxybiphenyl (2-HBP) as a dead end product. HN4 substantiated to be a hydrocarbon tolerant, biosurfactants(s) producer, and endorsed unique enzymatic system capable of desulfurizing broad range of thiophenic compounds and expressed an efficient desulfurization activity against the recalcitrant alkylated DBTs. As far our knowledge, it is the first reported BDS study using P. glucanolyticus. Statistical optimization based on One-Factor-At-A-Time (OFAT) technique and response surface methodology (RSM) applied for elucidation of mathematical model correlations describing and optimizing the effect of different physicochemical parameters on batch biphasic BDS process. That illustrated an approximate increase in BDS efficiency by 1.34 fold and recorded 94% sulfur removal in biphasic batch process at optimum operation conditions of 120 h, 0.14 wt% S-content model oil (DBT dissolved in n-hexadecane), 33.5 °C, pH7 and 1/1 oil/water phase ratio, and 147 rpm. Resting cells of HN4 in a biphasic reactor (1/1 v/v) decreased the sulfur content of a refractory thiophenic model oil (thiophene, benzothiophene, DBT, and alkylated DBT dissolved in n-hexadecane) from 0.14 to 0.027 wt%, and petro-diesel from 0.2 to 0.04 wt%, within 120 h, keeping the calorific value of the treated fuel intact. Consequently, that novel strain could be recommended as a promising candidate for BDS as complementary to hydrodesulfurization process in oil refinery.

Selective Oxidation of Crude Glycerol to Dihydroxyacetone in a Biphasic Photoreactor

In this paper, the first biphasic photoreactor was introduced and utilized for the conversion of glycerol to glyceraldehyde (GAD) and dihydroxyacetone (DHA) using water and ethyl acetate as dispersed (active) and continuous (inactive) phases, respectively. Increasing the ethyl acetate content in the reactor improved the DHA yield; however, the optimal DHA selectivity was obtained at an ethyl acetate to water ratio of 90:10 (vol/vol). Compared to a monophasic photoreactor containing only water and identical amounts of glycerol and photocatalyst, the biphasic reactor containing 90 vol % ethyl acetate increased the DHA yield by a factor of 2.9 (from 4.5% to 13%) and the concentration of DHA by approximately 14 times (from 0.08 mM to 1.1 mM) after 240 min. Additionally, photocatalytic conversion of crude glycerol extracted using a 90:10 (vol/vol) ethyl acetate-water mixture showed a similar DHA conversion and yield to that of pure glycerol.

High-Yield 5-Hydroxymethylfurfural Synthesis from Crude Sugar Beet Juice in a Biphasic Microreactor.

5‐Hydroxymethylfurfural (HMF) is an important biobased platform chemical obtainable in high selectivity by the hydrolysis of fructose (FRC). However, FRC is expensive, making the production of HMF at a competitive market price highly challenging. Here, it is shown that sugar beet thick juice, a crude, sucrose‐rich intermediate in sugar refining, is an excellent feedstock for HMF synthesis. Unprecedented high selectivities and yields of >90 % for HMF were achieved in a biphasic reactor setup at 150 °C using salted diluted thick juice with H2SO4 as catalyst and 2‐methyltetrahydrofuran as a bioderived extraction solvent. The conversion of glucose, obtained by sucrose inversion, could be limited to <10 mol %, allowing its recovery for further use. Interestingly, purified sucrose led to significantly lower HMF selectivity and yields, showing advantages from both an economic and chemical selectivity perspective. This opens new avenues for more cost‐effective HMF production.

Phase Transfer Catalyst Assisted One‐Pot Synthesis of 5‐(Chloromethyl)furfural from Biomass‐Derived Carbohydrates in a Biphasic Batch Reactor

Abstract5‐(Chloromethyl)furfural (CMF), a bio‐renewable chemical building block, has been produced in good isolated yields from biomass‐derived carbohydrates within a closed aqueous HCl‐1,2‐dichloroethane biphasic reactor in the presence of benzyltributylammonium chloride (BTBAC) as a phase transfer catalyst (PTC). The solvent‐economic, one‐pot strategy afforded CMF in 73% isolated yield (90 °C, 3 h) from sucrose with a combined yield of 84% for CMF and levulinic acid. The process was optimized on temperature, duration, solvent, type, and loading of PTC. Use of BTBAC led to nearly 10% increase in yield of CMF for all substrates when compared to control reactions.

Improved levulinic acid production from agri-residue biomass in biphasic solvent system through synergistic catalytic effect of acid and products

In this study, levulinic acid (LA) was produced from rice straw biomass in co-solvent biphasic reactor system consisting of hydrochloric acid and dichloromethane organic solvent. The modified protocol achieved a 15% wt LA yield through the synergistic effect of acid and acidic products (auto-catalysis) and the designed system allowed facile recovery of LA to the organic phase. Further purification of the resulting extractant was achieved through traditional column chromatography, which yielded a high purity LA product while recovering ∼85% wt. Upon charcoal treatment of the resultant fraction generated an industrial grade target molecule of ∼99% purity with ∼95% wt recovery. The system allows the solvent to be easily recovered, in excess of 90%, which was shown to be able to be recycled up to 5 runs without significant loss of final product concentrations. Overall, this system points to a method to significantly reduce manufacturing cost during large-scale LA preparation.

VOx Core–Shell Catalysts for One-Pot Oxidation and Separation of Refractory Multiaromatic Sulfur Compounds in a Model Diesel

Ti-MCM-41 supported vanadia core–shell catalysts were prepared and their catalytic activity was evaluated in a biphasic reactor for simultaneous oxidation/separation of refractory organosulfur compounds (dibenzothiophene (DBT), 4-methyldibenzothiophene (4-MDBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT)) in a model diesel fuel. Formation of core–shell structure in the catalyst nanoparticles resulted from the surface diffusion of the vanadium ion in semimelted state of vanadia during the calcination process. It was found that both the value of V5+/(V4+ + V5+) and the surface acidity of the catalysts generally increased as the content of V content increased to 15 wt % of vanadium and correlated well with variations in catalytic activity, indicating that the surface V5+ and surface acid sites were chiefly responsible for the oxidation of sulfur compounds. The reactivity of organosulfur compounds was influenced by their steric hindrance. Addition of carboxylic acid (acetic acid or formic acid) promoted the...

A thermodynamic and kinetic analysis of solvent-enhanced selectivity in monophasic and biphasic reactor systems.

Selectivity control in biomass conversion is often realized by manipulating the solvent environment. Outcomes can be rationalized through a thermodynamically rigorous application of transition-state theory. We show that solvent-induced perturbations to selectivity in both monophasic and biphasic reactor systems are governed by the same underlying principles.

Supramolecular Photocatalyst for the Reduction of Au(III) to Au(I) and High-Turnover Generation of Gold Nanocrystals

We report a photocatalyst composed of a diphenylanthracene core appended with two lipophilic thioether side-chains that binds gold(III) chloride. Upon excitation using visible light, the AuIII ions are smoothly reduced to AuI which, in the presence of water, lead to the formation of crystalline gold nanoparticles of 20–50 nm diameter that are devoid of sulfur-containing capping agents. Ultrafast transient absorption spectroscopy shows that the anthracene excited state is quenched with a rate k = 3.5 × 1010 s–1, assigned to intramolecular energy transfer to the bound gold ions, which then oxidizes the solvent to produce an intermediate low-valency gold(I) species. In the absence of water, the latter is stable and can be used as a homogeneous AuI catalyst. When employed in a biphasic reactor, the photocatalyst shows average turnover numbers of 150 atoms of AuIII reduced to Au0 per molecule of photocatalyst.

Thermophysical properties of 2,5-dimethylfuran and liquid–liquid equilibria of ternary systems water + 2,5-dimethylfuran + alcohols (1-butanol or 2-butanol or 1-hexanol)

Pure liquid properties, such as density, refractive index and dynamic viscosity of 2,5-dimethylfuran (DMF), a promising biofuel obtained from biomass, were determined over the temperature range (288.2–333.2)K. Liquid–liquid equilibrium (LLE) data of ternary systems water+DMF+alcohols (1-butanol or 2-butanol or 1-hexanol) were experimentally investigated at 298.2K and 313.2K at atmospheric pressure, using a jacketed glass equilibrium cell, according to a standard methodology. These alcohols are present in the DMF production process from dehydration of HMF in a biphasic reactor. The obtained results show that these alcohols are good solvents for use in DMF production, since large two-phase regions, great immiscibility and high selectivity for DMF were observed for all systems. The experimental ternary liquid–liquid equilibrium data were correlated using the NRTL and UNIQUAC models for the activity coefficient; the experimental nad calculated LLE data were in excellent agreement, with root mean square deviations below 1% for both NRTL and UNIQUAC models. The reliability of the experimental data was ascertained using the Bachman and Othmer–Tobias equations.

Reaction extraction of furfural from pentose solutions in a modified Scheibel column

Furfural, which is one of the most promising platform chemicals derived from biomass, has the potential for the production of biofuels and biochemicals. However, the current industrial furfural production process relies on relatively old and inefficient technology, which has some problems such as low production yields, environmental pollutions, and lack of biomass comprehensive utilization. The main contribution of this paper is the use of a modified Scheibel column to improve the furfural recovery. Integration of pentose dehydration to furfural and the solvent phase extraction of furfural occurred simultaneously in this column. Compared with the prevailing batch biphasic reactor, the use of this modified column intensified the extraction efficiency as well as the furfural recovery. Process parameters including organic feed flow rate, reaction temperature, and stirring speed were evaluated and turned out to be significant. In order to achieve the optimal operating conditions, the CCD design was used to optimize the process parameters, and the maximum furfural yield of 80.5% was obtained.

Mastering a biphasic single-reactor process for direct conversion of glycerol into liquid hydrocarbon fuels

Combination of aqueous-phase reforming of glycerol and Fischer–Tropsch synthesis in a single biphasic reactor in the presence of an acid leads to formation of long chain alkanes.

Multilevel rotating foam biphasic reactor for combination of processes in biomass transformation

The two-level rotating foam reactor has been developed for conducting of separate reactions in different phases in one reactor. The provided approach has been tested in the dehydration of xylose combined with produced furfural hydrogenation. The dehydration of xylose to furfural was carried out over zeolite MOR coated over Al foam in the aqueous phase and the hydrogenation of furfural over Ru impregnated over carbon foam in the organic phase. 2-Methyltetrahydrofuran and cyclohexane were used as solvents in the process. The main product of the combined process is tetrahydrofurfuryl alcohol.

Glucose Dehydration to 5‐Hydroxymethylfurfural in a Biphasic System over Solid Acid Foams

A solid acid foam-structured catalyst based on a binderless zirconium phosphate (ZrPO) coating on aluminum foam was prepared. The catalyst layer was obtained by performing a multiple washcoating procedure of ZrPO slurry on the anodized aluminum foam. The effect of the pretreatment of ZrPO, the concentration of the slurry, and the amount of coating on the properties of the foam was studied. The catalytic properties of the prepared foams have been evaluated in the dehydration of glucose to 5-hydroxymethylfurfural (HMF) in a biphasic reactor. The catalytic behavior of ZrPO foam-based catalysts was studied in a rotating foam reactor and compared with that of bulk ZrPO. The effect of a silylation procedure on the selectivity of the process was shown over bulk and foam catalysts. This treatment resulted in a higher selectivity due to the deactivation of unselective Lewis acid sites. Addition of methylisobutylketone leads to extraction of HMF from the aqueous phase and stabilization of the selectivity to HMF over bulk ZrPO. A more intensive contact of the foam with the aqueous and organic phases leads to an increase in the selectivity and resistance to deactivation of the foam in comparison with a bulk catalyst.

Mechanocatalytic Depolymerization of Dry (Ligno)cellulose As an Entry Process for High-Yield Production of Furfurals

Driven by mechanical forces, the acid-catalyzed depolymerization of solid biomass completely overcomes the problems posed by the recalcitrance of lignocellulose. The solid-state reaction leads to water-soluble oligosaccharides, which display higher reactivity than cellulose and hemicellulose. Here, we show that water-soluble oligosaccharides are useful feedstock for the high-yield production of 5-hydroxymethylfurfural (HMF) and furfural in biphasic reactors. This is because they readily undergo hydrolysis upon microwave heating, selectively forming monosaccharides as intermediates in the aqueous phase. Short reaction times are possible with the use of microwave heating and limit the extent of degradation reactions. This work provides an ionic-liquid-free approach to process lignocellulosic substrates into HMF and furfural with high yields. In fact, starting this novel approach with α-cellulose, yields of HMF of 79% and furfural of 80% at 443 K for 9 min were obtained. The processing of real lignocellulose (e.g., beechwood and sugar cane bagasse) also achieved high yields of HMF and furfural. Thereby, the current results indicate that the process limitation lies no longer in the recalcitrance of lignocellulose, but in the extraction of highly reactive HMF and furfural from the aqueous phase in the biphasic reactor.

Production of renewable petroleum refinery diesel and jet fuel feedstocks from hemicellulose sugar streams

We demonstrate how hemicellulose-derived C5 sugars can be converted into a high-quality petroleum refinery feedstock by a four-step catalytic process. The substitute petroleum consists of normal, branched and cyclic alkanes up to 31 carbons in length and is similar in composition to feedstocks produced in a petroleum refinery today from crude oil. This process can be tuned to adjust the size of the liquid alkanes. In the first step furfural is produced from the acid-catalyzed dehydration of hemicellulose-derived sugar streams in a biphasic reactor. The second step is the aldol condensation of furfural with acetone in a THF solvent and using a NaOH catalyst to produce highly conjugated C13 compounds along with some oligomeric adducts formed through Michael addition reactions. These compounds are then hydrogenated with a Ru/Al2O3 catalyst forming both the fully hydrogenated form of the C13 oligomers and also forming larger oligomers by Diels–Alder reactions. The extent of Diels–Alder reactions can be tuned by changing the temperature and feed concentration, thereby adjusting the distribution of liquid alkanes that can be produced. The final step in this process is hydrodeoxygenation using a Pt/SiO2–Al2O3 bifunctional catalyst to produce the liquid alkanes. A simple biorefinery model has shown that about 55% of a furfural–acetone mixture (10 : 3 wt ratio) can be converted into cycle oils while also producing other refinery products such as gasoline and natural gas.

Biphasic single-reactor process for dehydration of xylose and hydrogenation of produced furfural

The processes of xylose dehydration and the consecutive furfural hydrogenation have been combined in a single biphasic reactor. The dehydration was studied over Amberlyst-15 and the hydrogenation over a hydrophobic Ru/C catalyst. 1-Butanol, 2-methyltetrahydrofuran and cyclohexane were used as solvents in the process. The hydrogenation catalyst in the reactor was present in the organic phase and the dehydration catalyst in the aqueous phase. An increase of the hydrophobicity of the solvent in the order 1-butanol<2-methyltetrahydrofuran<cyclohexane suppressed the hydrogenation of xylose to xylitol due to a decrease of the xylose solubility, while forming furfural hydrogenation products. The main product is tetrahydrofurfuryl alcohol.

Bioconversion of p-coumaric acid to p-hydroxystyrene using phenolic acid decarboxylase from B. amyloliquefaciens in biphasic reaction system

Phenolic acid decarboxylase (PAD) catalyzes the non-oxidative decarboxylation of p-coumaric acid (pCA) to p-hydroxystyrene (pHS). PAD from Bacillus amyloliquefaciens (BAPAD), which showed k (cat)/K (m) value for pCA (9.3 × 10³ mM⁻¹ s⁻¹), was found as the most active one using the "Subgrouping Automata" program and by comparing enzyme activity. However, the production of pHS of recombinant Escherichia coli harboring BAPAD showed only a 22.7 % conversion yield due to product inhibition. Based on the partition coefficient of pHS and biocompatibility of the cell, 1-octanol was selected for the biphasic reaction. The conversion yield increased up to 98.0 % and 0.83 g/h/g DCW productivity was achieved at 100 mM pCA using equal volume of 1-octanol as an organic solvent. In the optimized biphasic reactor, using a three volume ratio of 1-octanol to phosphate buffer phase (50 mM, pH 7.0), the recombinant E. coli produced pHS with a 88.7 % conversion yield and 1.34 g/h/g DCW productivity at 300 mM pCA.