Ethanol Conversion Research Articles

Tailoring lattice oxygen triggered NiO/Ca9Co12O28 catalysts for sorption-enhanced renewable hydrogen production

Sorption-enhanced steam reforming of ethanol shows potential of supplying high-quality hydrogen with in situ CO2 capture, but suffers from sorbent deactivation. This paper describers the design of functionalized xNiO/Ca9Co12O28 materials, whose phases can be segregated once triggered by the lattice oxygen consumption via NiO/Ca9Co12O28-O2-→Ni-Co+CaO, thus acting as the catalytic sorbent. Their superiorities are demonstrated in: (i) low-temperature activation via lattice oxygen induction; (ii) recyclability via lattice oxygen replenishment; iii) high-quality hydrogen actuation via in situ CO2 adsorption. Hydrogen concentration of 95.56 vol% and near-complete ethanol conversion can be achieved. Moreover, stability across 50 repeated cycles without obvious reduction in catalytic reforming and CO2 adsorption is demonstrated. In situ XRD studies demonstrate the formation of the Ni-Co alloy and the reorganization of the catalytic sorbent. The adsorption energies of ethanol on the surface of Ni(111), Co(111), and Ni-Co(111) were studied by DFT calculations, reaffirming the higher catalytic activity of Ni-Co alloys.

Probing the promotional roles of lanthanum in physicochemical properties and performance of ZnZr/Si-beta catalyst for direct conversion of aqueous ethanol to butadiene

Here, the efficient synthesis of butadiene from aqueous ethanol was achieved over a series of x%LaZnZr/Si-beta multifunctional catalysts prepared by wet impregnation method. La species played a crucial role in improving the physicochemical properties and catalytic performance of the ZnZr/Si-beta catalyst. The structure and physicochemical properties of the synthesized catalysts were analyzed by multiple characterization technique. The characterization results revealed that the introduction of La species into ZnZr/Si-beta catalyst created a new La-O-Si bond, and rationally modified the acid-base properties. The La species substantially improved the main reaction of aldol condensation and inhibited the ethanol dehydration, as demonstrated by ethanol-TPD and TPSR studies. In addition, the adsorption capacity of water vapor was remarkably suppressed. A remarkable butadiene selectivity of 60.6 % and ethanol conversion of 83.4 % were achieved on the 5 %LaZnZr/Si-beta catalyst. This enhancement of butadiene selectivity and catalytic activity is very helpful for the development of novel efficient multifunctional catalysts for the direct synthesis butadiene from aqueous ethanol.

Genome-scale metabolic modelling enables deciphering ethanol metabolism via the acrylate pathway in the propionate-producer Anaerotignum neopropionicum

BackgroundMicrobial production of propionate from diluted streams of ethanol (e.g., deriving from syngas fermentation) is a sustainable alternative to the petrochemical production route. Yet, few ethanol-fermenting propionigenic bacteria are known, and understanding of their metabolism is limited. Anaerotignum neopropionicum is a propionate-producing bacterium that uses the acrylate pathway to ferment ethanol and CO2 to propionate and acetate. In this work, we used computational and experimental methods to study the metabolism of A. neopropionicum and, in particular, the pathway for conversion of ethanol into propionate.ResultsOur work describes iANEO_SB607, the first genome-scale metabolic model (GEM) of A. neopropionicum. The model was built combining the use of automatic tools with an extensive manual curation process, and it was validated with experimental data from this and published studies. The model predicted growth of A. neopropionicum on ethanol, lactate, sugars and amino acids, matching observed phenotypes. In addition, the model was used to implement a dynamic flux balance analysis (dFBA) approach that accurately predicted the fermentation profile of A. neopropionicum during batch growth on ethanol. A systematic analysis of the metabolism of A. neopropionicum combined with model simulations shed light into the mechanism of ethanol fermentation via the acrylate pathway, and revealed the presence of the electron-transferring complexes NADH-dependent reduced ferredoxin:NADP+ oxidoreductase (Nfn) and acryloyl-CoA reductase-EtfAB, identified for the first time in this bacterium.ConclusionsThe realisation of the GEM iANEO_SB607 is a stepping stone towards the understanding of the metabolism of the propionate-producer A. neopropionicum. With it, we have gained insight into the functioning of the acrylate pathway and energetic aspects of the cell, with focus on the fermentation of ethanol. Overall, this study provides a basis to further exploit the potential of propionigenic bacteria as microbial cell factories.

Chemical Synthesis Data Modeling Based on Mathematical Optimization

As one of the most important high value-added raw materials in the chemical industry, the synthesis of C4 Olefin by ethanol coupling was of great significance in the field of the chemical industry. Different catalysts and various conditions have different effects on the chemical reaction. This paper is based on the relevant data set. Firstly, Pearson and Spearman correlation coefficient method and corresponding hypothesis test are used to get the influence of different catalysts on the chemical reaction. Ethanol conversion and C4 Olefin selectivity are positively correlated with temperature. Secondly, a multivariate linear regression model with significant core variables is constructed to investigate the effects of catalyst combination and temperature on ethanol conversion and C4 Olefin selectivity. It can be concluded that the ethanol concentration is greatly affected by temperature and CO loading, and there is a positive and negative correlation between ethanol concentration and CO loading. The selectivity of C4 Olefin is affected by temperature and is positively correlated with the charge ratio of CO/SiO2 and HAP. Finally, by using a multiple regression equation and simulated annealing model, it can be obtained that when the loading of CO is 4.75 wt%, the loading ratio of CO/SiO2 and HAP is 1 : 1.4242, the concentration of ethanol is 0.3658 ml/min, and the temperature is 448.21°C, the loading ratio of CO/SiO2 and HAP is 1 : 1.4242, the concentration of ethanol is 0.3658 ml/min, and the temperature is 448.21°C, the yield of C4 Olefin can reach a higher value.

Immobilization of Alcohol Dehydrogenase, Acetaldehyde Lyase, and NADH Oxidase for Cascade Enzymatic Conversion of Ethanol to Acetoin

Acetoin, a four-carbon hydroxyl-keto compound, is used in the food, pharmaceutical, and chemical industries. The cascade enzymatic production is considered a promising and efficient method to produce acetoin. However, the stability and compatibility of the enzymes under the same catalytic conditions are challenges that need to be resolved. In this work, alcohol dehydrogenase, acetaldehyde lyase, and NADH oxidase were selected to work at the same conditions to efficiently convert ethanol into acetoin. These three enzymes were immobilized on epoxy-modified magnetic nanomaterials to obtain highly stable biocatalysts. The stability and the immobilization conditions, including temperature, pH, enzyme–carrier ratio, and immobilization time, were optimized to obtain the immobilized enzymes with a high catalytic activity. The cascade reactions catalyzed by the immobilized enzymes yielded a high conversion of 90%, suggesting that the use of immobilized enzymes is a promising way to produce acetoin.

Predicting the optimal chemical composition of functionalized carbon catalysts towards oxidative dehydrogenation of ethanol to acetaldehyde

A significant challenge in developing ideal carbon-based catalysts for oxidative dehydrogenation of ethanol to acetaldehyde is to correlate the catalytic efficiencies with the multiple functional sites on the catalysts qualitatively and quantitatively. By making a series of two-dimensional carbon catalysts with varied oxygen and nitrogen functional sites and testing the catalytic performances, we show the roles the specific functional groups played in the catalytic conversion process. Moreover, a map that includes the quantitative ratio of different active sites and the acetaldehyde yield is provided, which can be used to predict the ideal structure of a potential catalyst. The resulted catalyst showed the ethanol conversion rate of 54 %, the acetaldehyde selectivity of 84 %, and the attractive yield of acetaldehyde up to 45 %, surpassing the performances of the majority of reported carbon-catalysts tested under a similar condition. Our prediction reveals that the ideal balance of surface pyridinic-N/ graphitic-N in a carbon catalyst should be in the range of ~0.7–1.0 while the C-O/ CO is ~0.7–0.8, which could be very useful to the researches in this field. The combination of experiments, theoretical simulations, and especially the quantitative prediction deepens the understanding of the catalysts and the catalytic reactions, which is expected to be extended to the study of other catalytic processes.

Unzipping MWCNTs for controlled edge- and heteroatom-defects in revealing their roles in gas-phase oxidative dehydrogenation of ethanol to acetaldehyde

Bioethanol is a promising candidate for acetaldehyde production. In this study, we controllably unzipped multi-walled carbon nanotubes into open-edged nanotube/nanoribbon hybrids via a nano-cutting strategy for metal-free oxidative dehydrogenation of ethanol to acetaldehyde and unravelled the catalytic role of edge defects in the reaction. The edge-rich structure of the 1D-nanotube/2D-nanoribbon hybrid can accelerate the catalytic reaction more efficiently than pristine carbon sample. Moreover, edges can further accommodate nitrogen defects to preferentially form edge-doped nitrogen. Through engineering the concentration and speciation of defects, the structure-performance relationship between the defective structure and ethanol conversion rate is intensively investigated. Theoretical calculations unveil that the nitrogen doped at edge sites other than in basal planes can effectively facilitate O2 dissociation and formation of oxygen-containing active centers. Temperature-programmed ethanol desorption and kinetic measurements further supplement the catalytic interplay of edge and nitrogen defects on ethanol adsorption and reaction kinetics. The synergistic edge and nitrogen defects of the engineered hybrid produced a steady ethanol conversion of 47.9% and acetaldehyde selectivity of 90.2% at the gas hourly space velocity of 48,000 mL gcat-1h−1 on stream of 48 h. This work offers more insights to intrinsic properties and mechanism of enriched defective structures for development of effective carbocatalysts in catalytic applications.

Application of Multiple Linear Regression Analysis in the Preparation of C4 Olefins by Ethanol Coupling

For the preparation of C4 olefins by ethanol coupling, two-dimensional spline interpolation was performed on the original data to reduce the temperature interval.Then the correlation analysis was carried out to determine that the ethanol conversion rate and C4 olefin selectivity are strongly correlated with temperature, and the two are not independent of each other.Subsequently, a multivariate linear regression model was established to fit the ethanol conversion rate and C4 olefin selectivity, and the fitting equation was solved by the least square method. The relationship between the ethanol conversion rate, C4 olefin selectivity and temperature was analyzed by the fitted graph, and then the fitting results were judged and analyzed by the determination coefficient . Finally, the relationship between the selectivity of ethanol conversion products and time was observed by linear interpolation fitting.

Active and stable Cu doped NiMgAlO catalysts for upgrading ethanol to n-butanol

Upgrading ethanol to n-butanol is an attractive way for renewable n-butanol production. Herein, Cu was selected to modify NiMgAlO catalysts for improving ethanol conversion and n-butanol selectivity. Over the optimized 2%Cu-NiMgAlO catalyst, ethanol conversion and n-butanol selectivity were enhanced to 30.0% and 64.2%, respectively, in 200 h time on stream at 523 K. According to physicochemical characterizations and theoretical calculations, the key role of multiple active sites in this reaction was extensively investigated. The plate-like structure of hydrotalcite was maintained over 2%Cu-NiMgAlO catalysts, with an average Ni particle size of ca. 5.4 nm. The presence of Cu species created CuNi alloy sites and Lewis acid-base pairs, and increased hydrogen transfer and condensation reactions, resulting in elevated ethanol conversion and n-butanol selectivity. Additionally, CuNi alloy had a strong interaction with CuNiMgAl oxides, forming homogeneous boundary due to their close ionic radius and lattice matching, and afforded the long time stability in the ethanol to n-butanol reaction.

MOF-derived CoCeOx nanocomposite catalyst with enhanced anti-coking property for ethanol reforming with CO2

Up to date, to design the efficient catalysts for CO2 reforming with ethanol is of great challenge due to the severe coke deposition. In this work, MOF derived CoCeOx nanocomposite (CoCe-MOF) with outstanding performance for ethanol dry reforming was successfully prepared. Indeed, the experimental results revealed that ethanol conversion was 97% with a H2/CO ratio of ca.1 and negligible acetone formation (0.4 mol%) at 550 °C which was better than that of Co3O4/CeO2 synthesized by impregnation technique. Moreover, no obvious deactivation was observed even after 40 h time-on-stream tests for CoCe-MOF catalyst. Interestingly, ethanol conversion over CoCe-MOF slightly decreased from 99% to 96% while the value over Co3O4/CeO2 sample remarkably declined from 90% to 79% as well as the increase of byproduct formation (acetone from 1.1 mol% to 1.9 mol%). Particularly, the relationship between catalytic performance and morphology structure were investigated in detail by a series of characterization technique such as XRD, H2-TPR, BET, XPS, TEM, Raman etc. The results demonstrated that the uniform aliovalent incorporation of Co into CeO2 framework greatly improved the physicochemical features of the CoCe-MOF catalyst including the generation of more oxygen defects/surface oxygen species (14,5% of Ce3+ species), stronger Co-O-Ce interaction, lower temperature reducibility etc. Hence, these positive factors might explain its high activity and stability. Eventually, this study might provide a simple method to develop the high-performance catalysts for dry reforming process and other heterogeneous catalytic reactions.

Insights on the C2 and C3 electroconversion in alkaline medium on Rh/C catalyst: in situ FTIR spectroscopic and chromatographic studies

The present work evaluates ethanol and glycerol electro-oxidation on Rh/C catalysts prepared using the Bromide Anion Exchange (BAE) method. Physicochemical characterizations were performed using Thermogravimetric Analysis (TGA), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The SPAIRS investigations revealed that the CO adsorption modes on Rh sites occur on the linearly adsorbed CO (COL) and bridged bonded (COB) modes. In ethanol oxidation reaction (EOR), the Rh effect was evaluated by analyzing the products generated after bulk electrolysis using High-Performance Liquid Chromatography (HPLC) and in situ FTIR spectroscopy. The results confirmed the C-C cleavage Rh ability at low potentials and revealed that EOR follows both reaction pathways on Rh/C. While in glycerol oxidation reaction (GOR), Rh addition increases high added-value products formation such as glycerate ion. The GOR main route follows the glyceraldehyde pathway. The results highlighted that Rh is a good candidate for ethanol and glycerol electrochemical conversion at low potentials.

Experimental study on improving the efficiency of hydrogen production by partial oxidation of ethanol

Bioethanol as the renewable biomass fuel gradually becomes a promising feedstock for hydrogen production. To improve the efficiency of hydrogen production, a typical double-layer porous media burner was established for the partial oxidation reaction of ethanol (POE). The effects of porous media structure, initial ethanol and air conditions on the temperature distribution and gas production were investigated based on the start-up characteristics of the burner. The results indicate that the lowest start-up time (2400 s) and best hydrogen production (9.80%) were obtained by filling the downstream section with 8 mm Al2O3 pellets and introducing ethanol at the upstream inlet, compared with that of 6 and 10 mm pellets. The productions of methane and hydrogen were improved to some extent by adding the water with 10% fraction. And the highest concentration of hydrogen was achieved at the air velocity of 8 cm/s. When the O2/C ratios were 0.2 and 0.25, the maximum hydrogen yield (23.28%) and ethanol conversion (77.42%) were obtained respectively.

Cover Image, Volume 16, Issue 3

AbstractThe cover image is based on the Research Article Techno‐economic analysis of cellulosic ethanol conversion to fuel and chemicals by Steven Phillips et al., https://doi.org/10.1002/bbb.2346. image

Valorization of cocoa's mucilage waste to ethanol and subsequent direct catalytic conversion into ethylene

AbstractBACKGROUNDThe identification of new resources for producing biofuels and chemical‐based products is crucial for processes sustainability. This study presents a valorization route to produce ethanol and ethylene using cocoa's mucilage juice (MJ) residue from cocoa farms of variety ‘Arriba’ (AC). The processing parameters to maximize the ethanol production and subsequent selective conversion into ethylene were determined. Ethanol production has been carried out by investigating the effect of three parameters: the temperature of fermentation, the initial fermentation pH and the addition of (NH4)2SO4 as an N source in the presence of free Saccharomyces cerevisiae NCYC 366. Consecutively, the selectivity of ethanol–ethylene conversion using a zeolite‐based ZSM‐5 catalyst was evaluated at different temperatures and ethanol concentrations.RESULTSDuring ethanol production, the best sugar conversion was reached at 30 °C, adjusting the initial pH to 5 and without nitrogen source, resulting in 86.83% sugar conversion, the maximum ethanol concentration of 68.65 g L−1 and maximum ethanol production rate of 2.03 g L−1 h−1 after 168 h of fermentation. On the other hand, ethylene was produced using ZSM‐5‐based zeolite catalyst with >99.9% of efficiency in the temperature range 240–300 °C. In addition, selective ethylene formation was found at 240 °C and 30 g L−1 ethanol.CONCLUSIONThe approach hereby presented shows the valorization of MJ waste of AC variety to produce ethanol and ethylene with minimum processing input costs, demonstrating a successful route to convert a farm residue into a bio‐based product with enhanced marketability. © 2022 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Techno‐economic analysis of cellulosic ethanol conversion to fuel and chemicals

AbstractIn this paper, we describe multiple scenarios to assess the techno‐economic results of producing hydrocarbon fuels from corn stover‐derived ethanol and the impact of co‐producing higher‐value, ethanol‐derived n‐butanol and 1,3‐butadiene to improve economic feasibility. In our baseline process, the stover‐derived lignin is burned for its energy content to raise process steam and electricity. We evaluated an alternative approach based on the same stover‐to‐ethanol process, but instead of burning residual lignin to produce heat and electricity, it was fed to a hydrothermal liquefaction process and converted into hydrocarbon fuel, while the ethanol from fermentation is used to make only butanol or butadiene. Our results indicate that the hydrothermal liquefaction pathways have significant cost advantages over the pathways that burn the lignin. For comparison purposes, two more scenarios were evaluated based on the assumption that ethanol was purchased at market prices and converted to butanol or butadiene exclusively. This comparison evaluates the economics for making higher‐valued chemicals which, in the absence of incentives, would be the most profitable approaches in our study. The results for these evaluations indicated that the ethanol‐to‐butanol economics were generally favorable and achieved or exceeded the 10% internal rate of return target. The butadiene process had less favorable economic performance in some years when the market price for butadiene was less than the selling price needed to achieve the internal rate of return. Economic incentives for low‐carbon chemicals and fuels were not considered in our analysis. © 2022 Battelle Memorial Institute. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd.

Production of Hexanol as the Main Product Through Syngas Fermentation by Clostridium carboxidivorans P7.

The production of hexanol from syngas by acetogens has gained attention as a replacement for petroleum-derived hexanol, which is widely used in the chemical synthesis and plastic industries. However, acetogenic bacteria generally produce C2 compounds (e.g., acetate and ethanol) as the main products. In this study, the gas fermentation conditions favorable for hexanol production were investigated at different temperatures (30–37°C) and CO gas contents (30–70%) in batch gas fermentation. Hexanol production increased from 0.02 to 0.09 g/L when the cultivation temperature was lowered from 37 to 30°C. As the CO content increased from 30 to 70%, the CO consumption rate and hexanol production (yield, titer, and ratio of C6 compound to total products) increased with the CO content. When 70% CO gas was repeatedly provided by flushing the headspace of the bottles at 30°C, the total alcohol production increased to 4.32 g/L at the expense of acids. Notably, hexanol production (1.90 g/L) was higher than that of ethanol (1.20 g/L) and butanol (1.20 g/L); this is the highest level of hexanol produced in gas fermentation to date and the first report of hexanol as the main product. Hexanol production was further enhanced to 2.34 g/L when 2 g/L ethanol was supplemented at the beginning of 70% CO gas refeeding fermentation. Particularly, hexanol productivity was significantly enhanced to 0.18 g/L/day while the supplemented ethanol was consumed, indicating that the conversion of ethanol to acetyl-CoA and reducing equivalents positively affected hexanol production. These optimized culture conditions (gas fermentation at 30°C and refeeding with 70% CO gas) and ethanol supplementation provide an effective and sustainable approach for bio-hexanol production.

Cooperative role of cobalt and gallium under the ethanol steam reforming on Co/CeGaOx

The performance of gallium promoted cobalt-ceria catalysts for ethanol steam reforming (ESR) was studied using H2O/C2H5OH = 6/1 mol/mol at 500 °C. The catalysts were synthetized via cerium-gallium co-precipitation and wetness impregnation of cobalt. A detailed characterization by N2-physisorption, XRD, H2-TPR and TEM allowed the normalization of contact time and rationalization of the role of each catalysts component for ESR. The gallium promoted catalyst, Co/Ce90Ga10Ox, was more efficient for the ethanol conversion to H2 and CO2, and the production of oxygenated by-products (such as, acetaldehyde and acetone) than Co/CeO2. The catalytic performance is explained assuming that: (i) bare ceria is able to dehydrogenate ethanol to ethylene; (ii) Ce–O–Ga interface catalyzes ethanol reforming; (iii) both Ce–O–Co and Ce–O–Ga interfaces takes part in acetone production; and (iv) cobalt sites further allow C–C scission. It is suggested that a cooperative role between Co and Ce–O–Ga sites enhance the H2 and CO2 yields under ESR conditions.

Efficient Conversion of Ethanol to Hydrogen in a Hybrid Plasma-Catalytic Reactor

The present work describes highly efficient hydrogen production from ethanol in a plasma-catalytic reactor depending on the discharge power and catalyst bed temperature. Hydrogen production increased as the power increased from 15 to 25 W. A further power increase to 35 W did not increase hydrogen production. The catalyst was already active at a temperature of 250 °C, and its activity increased with increasing temperature to 450 °C. The further temperature increase did not increase the activity of the cobalt catalyst. The most important advantage of using the catalyst was the increased ethanol conversion to CO2 instead of CO production. As a result, the hydrogen yield was very high and reached 4.1 mol(H2)/mol(C2H5OH). This result was obtained with a stoichiometric molar ratio of water to ethanol of 3.

Efficient Plasma Technology for the Production of Green Hydrogen from Ethanol and Water

This study concerns the production of hydrogen from a mixture of ethanol and water. The process was conducted in plasma generated by a spark discharge. The substrates were introduced in the liquid phase into the reactor. The gaseous products formed in the spark reactor were hydrogen, carbon monoxide, carbon dioxide, methane, acetylene, and ethylene. Coke was also produced. The energy efficiency of hydrogen production was 27 mol(H2)/kWh, and it was 36% of the theoretical energy efficiency. The high value of the energy efficiency of hydrogen production was obtained with relatively high ethanol conversion (63%). In the spark discharge, it was possible to conduct the process under conditions in which the ethanol conversion reached 95%. However, this entailed higher energy consumption and reduced the energy efficiency of hydrogen production to 8.8 mol(H2)/kWh. Hydrogen production increased with increasing discharge power and feed stream. However, the hydrogen concentration was very high under all tested conditions and ranged from 57.5 to 61.5%. This means that the spark reactor is a device that can feed fuel cells, the power load of which can fluctuate.

Sm-CeO2/Zeolite Bifunctional Catalyst for Direct and Highly Selective Conversion of Bioethanol to Propylene

A series of Sm-CeO2/Beta composites with various Beta contents were prepared by an incipient impregnation method, followed by calcination at 650 °C. They were characterized by XRD, N2 adsorption, SEM, NH3-TPD, CO2-TPD and 27Al MAS NMR. The Sm-CeO2/Beta bifunctional catalysts exhibit eminent catalytic performances in the selective conversion of ethanol to propylene. In particular, the Sm-CeO2/10%Beta catalyst with 10% Beta zeolite gives the highest C3H6 yield of 59.3%. A good match between Sm-CeO2 and Beta accounts for its optimal result.