Alcohol Selectivity Research Articles

One-pot biosynthesis of furfuryl alcohol and lactic acid via a glucose coupled biphasic system using single Bacillus coagulans NL01

Furfuryl alcohol is an important reduction product from biomass derived furfural. This study developed one-pot biosynthesis of furfuryl alcohol and lactic acid by a glucose coupled biphasic system using single Bacillus coagulans NL01. Water/dioctyl phthalate is chosen as biphasic system to alleviate the toxicity of furfural and furfuryl alcohol. Under the optimal conditions, the high-concentration conversion (208 mM) of furfural was successfully converted in 6 h reaction with 98% furfural conversion and 88% furfuryl alcohol selectivity. Notably, glucose as co-substrate could be effectively converted to lactic acid in this biphasic system. About 264 mM furfuryl alcohol and 64.2 g/L lactic acid were simultaneously produced from 310 mM furfural and 71.3 g/L glucose within 8.5 h by a fed-batch strategy. The developed approach can not only increase the produced furfuryl alcohol concentration but also reduce the cost of overall approach by lactic acid co-production, indicating its potential for industrial applications.

Complete Liquid‐Phase Preparation of CuFe‐Based Catalysts and Their Application in the Synthesis of Higher Alcohols from Syngas

AbstractCuFe‐based catalysts with different Cu/Fe molar ratios were prepared by the complete liquid‐phase method and applied in the synthesis of higher alcohols from syngas in a slurry bed reactor. The characterization results demonstrated that the CuFe‐based catalysts existed CuFe alloy and CuFe2O4. The molar ratio of Cu/Fe had an obvious effect on the synergistic interaction of CuFe bimetallic and its performance. The CuFe‐based catalyst with Cu/Fe molar ratio of 2 (Cu2Fe1) was the best catalyst, which showed better dispersibility and intimate contact between bimetal, and more spinel on the metal surface. The activity evaluation results exhibited that low temperature and low pressure were favorable for the formation of higher alcohols. The total alcohols selectivity was 46.87% and the higher alcohols mass fraction in total alcohols was 83.44% at 493 K and 3 MPa. This work may provide a novel method in preparing a highly efficient catalyst for higher alcohols synthesis from syngas under milder reaction conditions.

Selective Liquid-Phase Oxidation of Toluene with Molecular Oxygen Catalyzed by Mn3O4 Nanoparticles Immobilized on CNTs under Solvent-Free Conditions

The catalytic performance of Mn3O4 supported on carbon nanotubes (CNTs) in the liquid-phase oxidation of toluene to benzyl alcohol and benzaldehyde was studied. The supported catalysts were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), N2 adsorption–desorption isotherms and ICP-MS. The results demonstrate that Mn3O4 nanoparticles loaded on CNTs performed better compared with pristine Mn3O4 or CNTs. The main reason for the increased catalytic activity is the dispersion and loading of Mn3O4 in CNTs. By optimizing the reaction temperature, reaction time, catalyst quality, oxygen flow rate and initiator dosage, the optimum reaction conditions were obtained. Using tert-butyl hydroperoxide (TBHP) as the initiator and oxygen as the oxidant, the toluene conversion rate was as high as 24.63%, and benzyl alcohol and benzaldehyde selectivity was 90.49%. The good stability of the catalyst was confirmed by repeating the experiment for four cycles and observing no significant changes in its performance.

Catalyzing learning with green chemistry undergraduate research

AbstractGreen chemistry and sustainability are important concepts to incorporate into the undergraduate chemistry curriculum. Through the development of innovative undergraduate chemistry research projects in these areas, retention of students in the physical sciences can be improved. This paper describes two projects in undergraduate catalysis research: hydrogenation of furfural and the esterification of biooil from pyrolyzed wood. Catalytic transfer hydrogenation (CTH) of furfural with Pd/C led to the production of furfuryl alcohol, furfuryl isopropyl ether, 2-methylfuran, and tetrahydrofurfuryl alcohol. The metal chloride additives improved selectivity for furfuryl alcohol and furfuryl isopropyl ether. Catalytic conversion of pyrolyzed wood biooil in ethanol with a solid acid catalyst yielded ethyl esters, including ethyl acetate and ethyl propionate, as characterized by GC/MS These projects are described in the context of engaging undergraduate students in hands-on research for the purpose of improving retention and persistence, as well as preparing young scientists to enter graduate programs and the STEM workforce.

Direct synthesis of allyl alcohol from glycerol over CoFe alloy

Allyl alcohol is a pivotal intermediate and it is of great importance to find a new way for the selective production of allyl alcohol from renewable and surplus glycerol. In this work, we want to report the high performance of CoFe alloy for the direct synthesis of allyl alcohol from glycerol. This alloy catalyst was prepared via the controlled calcination and reduction of CoFe-ZIF precursor. Characterization results indicate that Co can improve the activation of hydrogen and Fe enhances the acidity of prepared CoFe alloy. The activated hydrogen and acid sites in CoFe alloy played a synergistic effect for the selective formation of allyl alcohol directly from glycerol. The selectivity of allyl alcohol remained higher than 68.7 % with a 89.7 % conversion of glycerol at 250 °C, 2 MPa and WHSV = 2.6 h−1. And the reaction mechanism over CoFe alloy was proposed on the basis of controlled experiments.

Reduction of Vegetable Oil‐Derived Fatty Acid Methyl Esters toward Fatty Alcohols without the Supply of Gaseous H2

AbstractAn alternative route to the conventional one for fatty alcohol synthesis was investigated. It was possible to synthesize lauryl alcohol from methyl laurate via reduction by transfer of hydrogen and hydride in liquid phase, in noncatalytic reactions and without the supply of H2 gaseous. Pure NaBH4 or alumina‐supported NaBH4 and methanol were used as co‐reactants and 100% fatty alcohol selectivities were achieved. The aim of supporting the metal hydride was to increase its stability and achieve the full recovery of the solid at the end of reaction. When alumina‐supported NaBH4 was used, a final fatty alcohol yield of 93% was achieved. The use of methanol and NaBH4 in amounts higher than stoichiometric is important to generate alkoxyborohydride anions which act as better reducing species than NaBH4. The reaction conditions effect was investigated and the role of short carbon chain alcohol structure was elucidated. The effect of fatty acid methyl ester structure was also studied. Fatty acid methyl esters with shorter carbon chain length and without unsaturation (methyl laurate, methyl myristate) were easily reduced using NaBH4/Al2O3 and methanol reaching high conversions and fatty alcohol selectivities. Unsaturated fatty acid methyl ester with longer carbon chain (methyl oleate) introduced steric hindrance which disfavoured interaction between ester and reducing solid surface and fatty acid methyl ester conversion was noticeably lower. A reaction mechanism based on alkoxyborohydride anions as the actual reducing species was proposed. This mechanism fully interprets results obtained during fatty acid methyl ester reduction using short carbon chain alcohols and metal hydride.

Plasma-catalytic dry reforming of methane: Screening of catalytic materials in a coaxial packed-bed DBD reactor

The combination of catalysis with non-thermal plasma is a promising alternative to thermal catalysis. A dielectric-barrier discharge reactor was used to study plasma-catalytic dry reforming of methane at ambient pressure and temperature and a fixed plasma power of 45 W. The effect of different catalytic packing materials was evaluated in terms of conversion, product selectivity, and energy efficiency. The conversion of CO2 (~22%) and CH4 (~33%) were found to be similar in plasma-only and when introducing packing materials in plasma. The main reason is the shorter residence time of the gas due to packing geometry, when compared at identical flow rates. H2, CO, C2-C4 hydrocarbons, and oxygenates were identified in the product gas. High selectivity towards H2 and CO were found for all catalysts and plasma-only, with a H2/CO molar ratio of ~0.9. The lowest syngas selectivity was obtained with Cu/Al2O3 (~66%), which instead, had the highest alcohol selectivity (~3.6%).

Allyl alcohol production by gas phase conversion reactions of glycerol over bifunctional hierarchical zeolite-supported bi- and tri-metallic catalysts

The gas-phase conversion of glycerol into allyl alcohol over Fe–Mo and Cs–Fe–Mo/HZSM-5 (with SiO2/Al2O3 = 30 and 1500) zeolite catalysts in a packed-bed continuous flow reactor has been reported for the first time. To the best of our knowledge, the Cs–Fe–Mo/HZSM-5 catalyst appears to be most promising for gas-phase conversion of glycerol into allyl alcohol. The structure and catalytic performance for the glycerol conversion over bi- and tri-metallic-promoted zeolite catalysts were studied. The synthesized catalysts were characterized by ICP–AES, ICP–MS, N2 physisorption, SEM, STEM–EDX, XRD, NH3–TPD, CO2–TPD, XPS, TGA and pyridine-DRIFT techniques, which showed that differences in catalysts activity and product distribution are influenced by metal loading, changes of acid-base, and porosity. The most stable allyl alcohol selectivity achieved was 46.1 mol.% at 98.1 mol.% glycerol conversion over the 5wt.%Cs–2.5wt.%Fe–2.5wt.%Mo/HZSM-5 (SiO2/Al2O3 = 1500) catalyst achieved with 10 wt% glycerol feed at 350 °C reaction temperature after 26 h time-on-stream. The superior performance of the synthesized catalyst was attributed to the presence of the basic sites, high mesopore volume and mesopore surface area, balance between acidic-basic sites, synergetic interaction between metal species and ZSM-5 zeolite support. The reaction pathway mechanisms of glycerol to value-added allyl alcohol via the direct glycerol dehydration and hydrogen transfer mechanism over basic sites are proposed.

Elucidating the Role of Bifunctional Cobalt‐Manganese Catalyst Interactions for Higher Alcohol Synthesis

Catalyst promoters are often used to tune or improve performance with little understanding as to how they work. Here we present a fundamental evaluation of cobalt‐manganese interactions in Fischer‐Tropsch (FT) catalysis and evaluate a new bifunctional catalyst for CO dissociation and CO insertion mechanisms. FT has gained considerable attention recently due to the potential to convert bio or municipal waste feeds into commercial fuels and chemicals. Products are commonly highly linear paraffins, but here we show how the role of manganese can tune selectivity for linear olefins and alcohols in a copper, iron and alkali metal free cobalt bifunctional catalyst. These products also have significant commercial value for lubricants, plasticizers, detergents and base chemicals. Advanced catalyst characterization is shown with in situ techniques (XRD, EXAFS, PDF & TEM), while the FT products are fully analysed by NMR, GC and GCxGC. The role of manganese during catalyst synthesis is reviewed while fundamental understanding of the formation of a mixed metal oxide spinel is presented. The Co–Mn interactions change during catalyst reduction, with EXAFS showing cobalt metal and MnO as the main species present.

Upgrading of aqueous ethanol to fuel grade higher alcohols over dandelion-like Ni-Sn catalyst

Higher alcohols are increasingly attracting attention as transportation fuel additives due to the advantages over bioethanol that include higher heat value, less hygroscopic nature, and reduced-engine problems. Typically, bioethanol is produced as diluted aqueous solution from biomass fermentation, thus the direct upgrading of aqueous ethanol is favorable to avoid the costly isolation process. Here, the direct upgrading of aqueous ethanol to higher alcohols was successfully achieved by using the non-precious dandelion-like NiSnH catalysts under mild hydrothermal conditions, which exhibited a comparable catalytic activity with Pd/C catalyst. Spontaneous phase-separable higher alcohol product was obtained, the C4+ higher alcohol selectivity reached 91.6% with iso-/n- ratio of 0.83 in the liquid products, which makes it suitable to be directly used as fuel additives. The promotion role of Ni-Sn catalyst on the production of higher alcohols and possible reaction pathway were also discussed.

The effect of metal precursor on copper phase dispersion and nanoparticle formation for the catalytic transformations of furfural

The formation of copper-based catalysts ranging from nanoparticles to isolated and dimeric Cu species supported on nanophased alumina is reported and utilised for the catalytic liquid-phase hydrogenation of furfural. The materials were synthesised via wet impregnation using various copper precursors (nitrate, acetate and sulphate) at two different loadings. A high Cu loading (5.0 wt.%) led to the formation of well-defined nanoparticles, while a lower loading (1.0 wt.%) generated a highly dispersed phase consisting mostly of atomic and dimeric Cu species dispersed on Al2O3. The catalytic reaction was found to be structure sensitive, promoting decarbonylation reactions with low Cu loading. Copper sulphate derived catalysts were found to severely decrease furfuryl alcohol selectivity from 94.6% to 0.8%, promoting the formation of side reactions. The sulphur-free catalysts represent a greener and more sustainable alternative to the toxic catalysts currently used in industry, operating at milder conditions of 50 °C and 1.5 bar H2.

Preparation and Structural Characterization of Platinum Nanosheets Intercalated between Graphite Powder with High Surface Area

Synthesis of platinum nanoparticles intercalated between layers of commercially available graphite powder samples possessing surface area values ranging from 20 to 750 m2 g-1 was attempted by the insertion of platinum chloride between the layers followed by hydrogen reduction. Platinum nanosheets with 1-4 nm thickness and 5-300 nm width and hexagonal holes were obtained for the graphite powder with 20 m2 g-1 independent of the platinum loadings (5, 10, and 15 wt%). Platinum nanosheets with the similar size (1-4 nm thickness and 5-300 nm width) and hexagonal holes were formed for graphite powder with 120 and 300 m2 g-1 with only 15 wt% platinum loading, but not for 5 and 10 wt% platinum loadings. Interestingly, for the graphite powder with higher surface area of 500 and 750 m2 g-1, platinum nanosheets were not formed. Platinum nanosheets intercalated between graphite samples were evaluated for cinnamaldehyde hydrogenation in supercritical carbon dioxide solvent. High cinnamyl alcohol selectivity was obtained for the platinum nanosheets intercalated between graphite layers having surface area of 20 m2 g-1; however, hydrocinnamaldehyde selectivity was high for the platinum nanosheets intercalated between graphite samples having surface area of 120 m2 g-1.

Enhanced C3+ alcohol synthesis from syngas using KCoMoSx catalysts: effect of the Co-Mo ratio on catalyst performance

K-Co-MoSx catalysts varying in Co content were prepared to investigate the role of Co in this catalyst formulation for the synthesis of C3+ alcohols from syngas. The Co-MoSx precursors and the best performing K-doped version were characterized in detail and the amount of active cobalt sulfide and mixed metal sulfide (Co-Mo-S) phases were shown to be a function of the Co content. The catalysts were tested in a continuous set-up at 360 °C, 8.7 MPa, a GHSV of 4500 mL g-1 h-1 and a H2/CO ratio of 1. The highest alcohol selectivity of 47.1%, with 61% in the C3+ range, was obtained using the K-Co-MoSx catalyst with a Co/(Co + Mo) molar ratio of 0.13. These findings were rationalized considering the amount and interactions between cobalt sulfide and Co-Mo-S or MoS2 phases. Process studies followed by statistical modeling gave a C3+ alcohol selectivity of 31.0% (yield of 9.2%) at a CO conversion of 29.8% at optimized conditions.

Stabilization of Fast Pyrolysis Liquids from Biomass by Mild Catalytic Hydrotreatment: Model Compound Study

Repolymerization is a huge problem in the storage and processing of biomass pyrolysis liquid (PL). Herein, to solve the problem of repolymerization, mild catalytic hydrotreatment of PL was conducted to convert unstable PL model compounds (hydroxyacetone, furfural, and phenol) into stable alcohols. An Ni/SiO2 catalyst was synthesized by the deposition-precipitation method and used in a mild hydrotreatment process. The mild hydrotreatment of the single model compound was studied to determine the reaction pathways, which provided guidance for improving the selectivity of stable intermediate alcohols through the control of reaction conditions. More importantly, the mild hydrotreatment of mixed model compounds was evaluated to simulate the PL more factually. In addition, the effect of the interaction between hydroxyacetone, furfural, and phenol during the catalytic hydrotreatment was also explored. There was a strange phenomenon observed in that phenol was not converted in the initial stage of the hydrotreatment of mixed model compounds. Thermogravimetric analysis (TGA), Ultraviolet-Raman (UV-Raman), and Brunauer−Emmett−Teller (BET) characterization of catalysts used in the hydrotreatment of single and mixed model compounds demonstrated that this phenomenon did not mainly arise from the irreversible deactivation of catalysts caused by carbon deposition, but the competitive adsorption among hydroxyacetone, furfural, and phenol during the mild hydrotreatment of mixed model compounds.

Continuous Hydrogenation of Aqueous Furfural Using a Metal-Supported Activated Carbon Monolith.

Continuous hydrogenation of aqueous furfural (4.5%) was studied using a monolith form (ACM) of an activated carbon Pd catalyst (∼1.2% Pd). A sequential reaction pathway was observed, with ACM achieving high selectivity and space time yields (STYs) for furfuryl alcohol (∼25%, 60–70 g/L-cat/h, 7–15 1/h liquid hourly space velocity, LHSV), 2-methylfuran (∼25%, 45–50 g/L-cat/h, 7–15 1/h LHSV), and tetrahydrofurfuryl alcohol (∼20–60%, 10–50 g/L-cat/h, <7 1/h LHSV). ACM showed a low loss of activity and metal leaching over the course of the reactions and was not limited by H2 external mass transfer resistance. Acetic acid (1%) did not significantly affect furfural conversion and product yields using ACM, suggesting Pd/ACM’s potential for conversion of crude furfural. Limited metal leaching combined with high metal dispersion and H2 mass transfer rates in the composite carbon catalyst (ACM) provides possible advantages over granular and powdered forms in continuous processing.

Simultaneous dehydrogenation of 1,4- butanediol to γ-butyrolactone and hydrogenation of benzaldehyde to benzyl alcohol mediated over competent CeO2–Al2O3 supported Cu as catalyst

Hydrogen being a dynamically impending energy transporter is widely used in hydrogenation reactions for the synthesis of various value added chemicals. It can be obtained from dehydrogenation reactions and the acquired hydrogen molecule can directly be utilized in hydrogenation reactions. This correspondingly avoids external pumping of hydrogen making it an economical process. We have for the first time tried to carryout 1,4-butanediol dehydrogenation and benzaldehyde hydrogenation simultaneously over ceria-alumina supported copper (Cu/CeO2–Al2O3) catalyst. In this concern, 10 wt% of Cu supported on CeO2–Al2O3 (3:1 ratio) was synthesized using wet impregnation method. The synthesized catalyst was then characterized by various analytical methods such as BET, powder XRD, FE-SEM, H2-TPR, NH3 and CO2-TPD, FT-IR and TGA. The catalytic activity towards simultaneous 1,4-butanediol dehydrogenation and benzaldehyde hydrogenation along with their individual reactions was tested for temperature range of 240 °C–300 °C. The physicochemical properties enhanced the catalytic activity as clearly interpreted from the results obtained from the respective characterization data. The best results were obtained with 10 wt% of Cu supported on CeO2–Al2O3 (3:1 ratio) catalyst with benzaldehyde conversion of 34% and 84% selectivity of benzyl alcohol. The conversion of 1,4-butanediol was seen to be 90% with around 95% selectivity of γ-butyrolactone. The catalyst also featured physicochemical properties namely increased surface area, higher dispersion and its highly basic nature, for the simultaneous reaction towards a positive direction. In terms of permanence, the Cu/CeO2–Al2O3 (10CCA) catalyst was quite steady and showed stable activity up to 24 h in time on stream profile.

A robust strategy of homogeneously hybridizing silica and Cu3(BTC)2 to in situ synthesize highly dispersed copper catalyst for furfural hydrogenation

Catalyst deactivation caused by the metal sintering/leaching is still a great challenge confronted by the scientists. Herein, we report a robust strategy to in situ synthesize mesoporous silica supported highly dispersed copper catalyst by homogeneously hybridizing the silica and metal-organic framework (MOF) copper benzene-1,3,5-tricarboxylate (Cu3(BTC)2). We find the introducing silica is the key to the formation of homogeneous hybridization by regulating the growth of Cu-BTC crystallite, yielding various metal dispersion and reducibility during calcination; while the added BTC ligands acts as porous initiator, promoting the accessibility of copper centers for reactants. The optimized CuO#SiO2–s1 with molar ratio Cu/Si of 0.23, exhibits excellent catalytic performance towards the furfural hydrogenation, showing a high activity as 9.2 molFF molCu−1 h−1, nearly 100 % furfural alcohol selectivity and minimized activity decline (<5%) after 5 repeated run. This work could open up a new avenue for the synthesis of mesoporous silica supported highly dispersed metal catalyst for hydrogenation.

Synergistic catalysis of hybrid nano-structure Pd catalyst for highly efficient catalytic selective hydrogenation of benzaldehyde

Selective hydrogenation of benzaldehyde is a green and sustainable technology to produce benzyl alcohol. Herein, we report a hybrid nano-structure catalyst(Pd/@-ZrO2/AC) by photochemical route for selective hydrogenation of benzaldehyde under mild reaction conditions. The Pd/@-ZrO2/AC catalyst exhibited outstanding activity(100%) and high selectivity for benzyl alcohol (>98 %), much higher than that of Pd/ZrO2 and Pd/AC. The high catalytic activity was attributed to the special structure and the synergistic effect. A series of Pd/@-MexOy/AC(MexOy: TiO2, CeO2, La2O3) catalysts further confirmed the synergistic effect in this hybrid nano-structure for this reaction. This work clearly demonstrates that loading nano-metal on high specific surface area materials with nano-semiconductors can increase the catalytic activity and open up a new direction for the synergistic catalysis of hybrid nano-structure catalysts.

Conversion of biorenewably available acetone and butanol to liquid fuels using base catalysts

We studied acetone butylation over KF/Na-ZSM-5 and ZSM-5 impregnated with other K-compounds which impart basicity. These base catalysts have, so far, not been reported for ketone alkylation. These catalysts did not contain any metal any of metal which are conventionally used to affect dehydrogenation-hydrogenation reactions which have been reported to be involved in mechanism of acetone alkylation. Absence of such metals reduces catalyst costs and eliminates metal sintering. Catalyst basicity was determined by FTIR of pyrrole-adsorbed samples and CO2 adsorption method. Coke deposited after reaction for 20 h time-on-stream on promising catalyst, namely, 10 wt% KF/Na-ZSM-5, was characterized by TGA and GCMS. This confirmed stability of KF on Na-ZSM-5, without leaching of F. Acetone conversion (60%) and ketone plus alcohol selectivity (exceeding 90%) surpassed reported performance at comparable operating conditions.

The Fischer-Tropsch reaction in the aqueous phase over rhodium catalysts: a promising route to selective synthesis and separation of oxygenates and hydrocarbons.

In the present communication, we uncovered the aqueous phase Fischer-Tropsch reaction over rhodium catalysts. The reaction results in the synthesis and consecutive separation of hydrocarbons and oxygenates into two phases. Use of a rhodium Schiff base complex as a precursor for catalyst preparation allows efficient control of the Rh metal nanoparticle size distribution and leads to higher alcohol selectivity.