Conversion Of Bioethanol Research Articles

Fluoride-Treated Nano-HZSM-5 Zeolite as a Highly Stable Catalyst for the Conversion of Bioethanol to Propylene.

Fluoride treatment of ZSM-5 zeolite can effectively adjust surface acidity and generate a secondary pore structure. In this study, a series of modified nano-HZSM-5 zeolites were prepared by NH4F-HF mixed solution treatment and applied to the selective conversion of bioethanol to propylene at 500 °C, atmospheric pressure, and a WHSV of 10 h-1. The results showed that NH4F-HF modification weakened the surface acidity of nano-HZSM-5 zeolites, thus inhibiting coke formation. Additionally, the mesopores in the nano-HZSM-5 zeolites increased after NH4F-HF treatment, thereby enhancing the mass transfer rate and improving the coke-resistance ability. The NH4F-HF mixed solution modification significantly improved the stability of nano-HZSM-5 zeolites in catalyzing bioethanol to propylene and greatly extended the working life of nano-HZSM-5 zeolites. It can be seen from the characterization of the deactivated catalysts that coke deposition and weakening of acidity may be the key factors for catalyst deactivation.

Novel cofactor regeneration-based magnetic metal–organic framework for cascade enzymatic conversion of biomass-derived bioethanol to acetoin

Upgrading biomass-derived bioethanol to higher-order alcohols using conventional biotechnological approaches is challenging. Herein, a novel, magnetic metal–organic-framework-based cofactor regeneration system was developed using ethanol dehydrogenase (EtDH:D46G), NADH oxidase (NOX), formolase (FLS:L482S), and nicotinamide adenine dinucleotide (NAD+) for converting rice straw-derived bioethanol to acetoin. A magnetic zeolitic imidazolate framework-8@Fe3O4/NAD+ (ZIF-8@Fe3O4/NAD+) regeneration system for cell-free cascade reactions was introduced and used to encapsulate EtDH:D46G, NOX, and FLS:L482S (ENF). ZIF-8@Fe3O4/NAD+ENF created an efficient microenvironment for three-step enzyme cascades. Under the optimized conditions, the yield of acetoin from 100 mM bioethanol using ZIF-8@Fe3O4/NAD+ENF was 90.4 %. The regeneration system showed 97.1 % thermostability at 50 °C. The free enzymes retained only 16.3 % residual conversion, compared with 91.2 % for ZIF-8@Fe3O4/NAD+ENF after ten cycles. The magnetic metal–organic-framework-based cofactor regeneration system is suitable for enzymatic cascade biotransformations and can be extended to other cascade systems for potential biotechnological applications.

Eco-Friendly Transformation of Bioethanol into Ethylene over Bimetallic Nickel-Copper Catalysts.

The conversion of bioethanol to ethylene in gas phase and atmospheric pressure was investigated over γ-Al2O3 supported copper and nickel catalysts. These catalysts were prepared by co-precipitation and pre-treated with hydrogen at 450 °C. Six catalysts were studied at 450 °C under a nitrogen atmosphere. It was found that the monometallic Cu/γ-Al2O3 catalyst exhibited the highest ethylene concentration, with a selectivity of around 90 %. The bioethanol conversion obtained was between 57 %-86 %. Another catalyst that exhibited high concentration values was the NiCu1 : 7 bimetallic catalyst. The catalysts were characterised using XRD, SEM, EDS, TEM, TGA, FTIR, Raman, and N2-physisoption techniques. Furthermore, the Cu/γ-Al2O3 catalyst was studied under different reduction temperatures and gas flow conditions. It was found that the catalysts reduced at 350 °C and 35 ml/min N2 flow presented ethylene concentrations between (0.18-0.21) g/L. Moreover, the catalyst deactivation was identified to be first order and the equation of the Cu/γ-Al2O3 catalyst deactivation model was determined. Carbonaceous deposits over the used sample were not detected by Raman and FTIR. It was determined that the Cu/γ-Al2O3 catalyst deactivation could be mainly attributed to the blocking of the catalytic sites by strongly adsorbed compounds and hydroxylation of the catalyst surface.

Surface hydrophobicity and catalytic performance of cerium incorporated HZSM-5 zeolite for conversion of bio-ethanol

Cerium incorporated HZSM-5 (CeHZSM-5) catalyst prepared by impregnation method was tested for aqueous ethanol conversion at 200–400 °C. The CeHZSM-5 catalyst was found to be very active (21.02 %Conversion), compared to the parent HZSM-5 catalyst (9.39 %Conversion), especially at low reaction temperatures (200 °C) and when fed with high water content (80 wt% ethanol). FTIR, FT-Raman, DR-UV, NH3-TPD, IPA-TPD, DSC and contact angle techniques reveal that the incorporation of cerium species into zeolites results in the acidity and hydrophilic/hydrophobic nature. Cerium species are thought to tend to migrate into ZSM-5 channels and associate with the zeolite framework. As a result, the net electrostatic charge decreases due to the presence of tetrahedral cerium atoms. Therefore, the CeHZSM-5 exhibits a hydrophobic character, compared to the parent one. The decrease in competitive adsorption of water versus ethanol feed at the Brønsted acid site may lead to an increase in CeHZSM-5 catalyst activity.

Techno-economic and life-cycle analysis of single-step catalytic conversion of bioethanol to fuel blendstocks over Ni-doped HZSM-5 zeolite catalyst

This work presents techno-economic and life-cycle studies focusing on the catalytic conversion of ethanol into hydrocarbon fuel blendstocks. These analyses benefit from recent advancements in catalyst and process development. The consolidated alcohol dehydration and oligomerisation for ethanol-to-hydrocarbon (CADO-ETH) conversion approach, described here, achieves a single-step transformation of wet ethanol vapour into hydrocarbons and H2O using a Ni-doped HZSM-5 catalyst. Catalyst cost estimation using the CatCost model showed that commercial synthesis of Ni/HZSM-5 incurred significant processing costs, which varied greatly depending on the manufacturing scale. Hence, catalyst production using 100 % and 50 % baseline scale production (BSP) requirements resulted in net catalyst costs of $31.4 and $69.9/kg, respectively. Although current CADO products closely resemble gasoline blendstocks, they can also be blended with gasoline fuel at low levels. There is potential for higher-level blending in the future. The operating and annualised capital costs for converting wet ethanol into fuel blendstocks were predicted to be $0.05/L at present and projected to decrease to $0.03/L in the future. This cost is comparable to the unit energy cost of synthesising anhydrous ethanol from wet ethanol, which is $0.02/L. At an oil price of 100 $/bbl, the expected minimum selling prices for the fuel blendstocks produced by CADO are similar to the prices for conventional gasoline. However, at an oil price of $60/bbl, the estimated minimum selling prices for CADO-derived blendstocks are not competitive with conventional gasoline. Nevertheless, considering existing production incentives, the projected minimum selling price for gasoline blendstock is comparable to the oil price of $60/bbl. The LCA shows that the CO2 emissions of gasoline produced from crude oil are 90.2 gCO2 e/MJ, which is 25 %, 53 % and 63 % more than the emissions of gasoline produced from corn starch, sugarcane, and cane cellulose, respectively. The results of this study indicate that the single-step CADO-ETH technology is promising for the production of renewable fuels and offers a potential pathway to reduce the carbon footprint.

Industrial crude bioethanol dehydration to ethylene: Doping ZSM-5 to enhance selectivity and stability

Although the conversion of bioethanol into light olefins is one of the most studied processes in biorefinery schemes, there is a need to develop materials more capable of operating at industrial conditions (WHSV > 20 h−1 crude bioethanol feed). Hence, in this study, we dehydrated crude bioethanol samples derived from sugarcane fermentation to produce ethylene over a series of H-ZSM-5 zeolites. Among them, H-ZSM-5 with different Si/Al ratios (26, 280, and 371) and doped with Ce and Cu were tested on the catalytic activity and stability. Accordingly, a 26 Si/Al ratio showed full conversion and ethylene selectivity at 300 °C with a WHSV of 30.2 h−1. When doping the zeolites, a decrease in relative crystallinity and a higher amount of acid sites were observed, which affected the interaction with reactants. This interaction was deeply analyzed by the in-situ DRIFTS, which showed that ethanol adsorption is lower for doped zeolites, but the desorption rate is higher, showing higher stability over longer reaction times. Therefore, the H-ZSM-5 with a Si/Al ratio of 26 and doped with Ce maintained its activity and improved its selectivity over 140 h under more drastic conditions of WHSV (42.3 h−1). These results elucidate that Ce-doped H-ZSM-5 zeolites can improve stability and represent a starting point for large-scale crude bioethanol conversion.

Multiple synergistic roles of Zr modification on ZSM-5 in performant and stable catalyst for ethanol conversion to propene

Bioethanol to propene is a promising avenue to produce propene by non-fossil routes. In this study, the ethanol conversion on metal-modified ZSM-5 catalysts is systematically investigated under catalyst preparation conditions and reaction parameters. Among all metal modified ZSM-5, Zr modification significantly improves the propene selectivity and catalyst durability. On the Zr/ZSM-5 catalyst (Zr/Al molar ratio is 0.4, reaction temperature 500 °C, and contact time 0.005 g⋅min/mL), the maximum yield of propene reaches up to 32.5 %, which can be maintained above 20.0 % within 20 h. Zr modification changes the acidity and electronic structure of the active sites, improves the adsorption stability of the reactant ethanol on Zr/ZSM-5, facilitates easier desorption of the product propene, benefiting propene production. Moreover, Zr modification is found to increase the activation energy of the ethene protonation, inhibit the ethene dimerization reaction, further inhibits the carbon deposition, and extends the lifetime of ZSM-5. In addition to its synergistic and effective role in the conversion of ethanol to propene, the Zr modified catalyst also exhibits high selectivity and stability in the conversion of bioethanol. According to above significant characteristics, Zr modified ZSM-5 will emerge as a promising catalyst for the conversion of bioethanol to propene.

Ni-Based Hydrotalcite (HT)-Derived Cu Catalysts for Catalytic Conversion of Bioethanol to Butanol.

Catalytic conversion of biomass-derived ethanol into n-butanol through Guerbet coupling reaction has become one of the key reactions in biomass valorization, thus attracting significant attention recently. Herein, a series of supported Cu catalysts derived from Ni-based hydrotalcite (HT) were prepared and performed in the continuous catalytic conversion of ethanol into butanol. Among the prepared catalysts, Cu/NiAlOx shows the best performance in terms of butanol selectivity and catalyst stability, with a sustained ethanol conversion of ~35% and butanol selectivity of 25% in a time-on-stream (TOS) of 110 h at 280 °C. While for the Cu/NiFeOx and Cu/NiCoOx, obvious catalyst deactivation and/or low butanol selectivity were obtained. Extensive characterization studies of the fresh and spent catalysts, i.e., X-ray diffraction (XRD), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Hydrogen temperature-programmed reduction (H2-TPR), reveal that the catalysts' deactivation is mainly caused by the support deconstruction during catalysis, which is highly dependent on the reducibility. Additionally, an appropriate acid-base property is pivotal for enhancing the product selectivity, which is beneficial for the key process of aldol-condensation to produce butanol.

Increasing Profitability of Ethanol Photoreforming by Simultaneous Production of H2 and Acetal.

Often, H2 is produced photocatalytically at the expense of sacrificial agents. When a sacrificial agent is selectively oxidized, this allows coupling of H2 production with synthesis of value-added organic compounds. Herein, it is argued that the conversion of bioethanol into 1,1-diethoxyethane with simultaneous H2 production increases the economic viability of photocatalysis and suggests a semiconductor material that is the most relevant for this purpose.

Dehydration of bioethanol over phosphotungstic acid immobilized onto nanoporous activated carbons: thermodesorption and catalytic studies

Phosphotungstic acid (PTA) was immobilized onto the porous structures of three nanoporous activated carbons (NACs), including oxidized, thermally treated, and pristine NACs. The PTA-NAC catalysts with different oxygen-containing functional groups on the carbon surface were obtained. The prepared catalysts can catalyze the reaction of bioethanol dehydration; they stimulate the formation of diethyl ether and ethylene. These catalysts showed high diethyl ether yields of up to 65% and excellent selectivities of up to 93% at 130–160 °С. The conversion of bioethanol to ethylene increased with increasing reaction temperature, and the ethylene yield reached almost 100% with about 100% selectivity at 190–220 °С.

Bioethanol as a potential eco‐friendlier feedstock for catalytic production of fuels and petrochemicals

AbstractBioethanol, synthesized through the valorization of biomass resources, is of great importance to many industries. As bioethanol has become more abundant and its price has decreased, it has become an attractive candidate for application as a base material for the synthesis of a variety of petrochemicals and fuel through catalysis. In this article, a comprehensive review of the catalytic conversion of bioethanol into hydrocarbons, including olefins and gasoline, is presented. In addition, developments and potential research opportunities in the field of bioethanol catalysis are provided to enhance bioethanol conversion. According to the findings of the study, despite significant progress in bioethanol conversion, further research is needed to address several challenges that will enable improved biofuel and chemical production. © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Copper Supported on MgAlOx and ZnAlOx Porous Mixed-Oxides for Conversion of Bioethanol via Guerbet Coupling Reaction

The direct conversion of biomass-derived ethanol to high-valued-added chemicals has attracted widespread attention recently due to the great economic and environmental advantages. In the present study, the conversion of bioethanol through the Guerbet coupling process was studied in a fixed-bed reactor for MgAlOx and ZnAlOx mixed-oxides supported Cu catalysts. From the results, Cu adding into the system greatly enhance the dehydrogenation of ethanol and increase the H-transfer in the course of Guerbet coupling process. Simultaneously, the porous mixed-oxides provide the acid-base property of the catalysts for intermediate transformation. Notably, for Cu/MgAlOx, the main product of ethanol conversion is butanol, but for Cu/ZnAlOx, the primary product is ethyl acetate. Characterizations such as X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and CO2 temperature programmed desorption (TPD) were carried out to evaluate the structure and property of the catalysts. In combination with the catalytic performances with the characterization results, the synergistic catalytic effect between metal sites and acid-base sites were elaborated.

Efficient Catalytic Upgrading of Ethanol to Higher Alcohols via Inhibiting C–C Cleavage and Promoting C–C Coupling over Biomass-Derived NiZn@NC Catalysts

The conversion of renewable bioethanol into high-energy-density higher alcohols has become essential for meeting the increasing global demand to achieve carbon neutrality. In this study, Zn- and nitrogen-codoped Ni-based lignin-derived carbon catalysts (NiZn@NC) were prepared by solvent volatile self-assembly and in situ reductive carbonization using pulp and paper waste stream alkali lignin as the carbon source. Lignin amphipathic derivatives with −COOH and −NH2 groups would coordinate with metal ions to form a stable lignin–metal framework; thus, the lignin-derived carbon layer disperses the NiZn bimetallic catalyst and prevents from corroding. At an amination reagent/lignin mass ratio of 1:2, an ethanol conversion of 75.2% and a high alcohol yield of 41.7% were achieved over the Ni20Zn1@NC catalyst. Experimental results and density functional theory calculations showed that Zn doping improved the electronic environment and defect structures of metallic Ni and carbon carrier, which effectively inhibited C–C cleavage and suppressed the byproduct formation, such as methane. Thereby, the synergetic effect between Ni and Zn facilitated the efficient conversion of aqueous ethanol into higher alcohols by the Guerbet reaction. This work provides a strategy of in situ pyrolytic doping and stabilizing of renewable biomass macromolecules as the frameworks for the construction of highly active and cost-efficient catalysts for ethanol upgrading.

Bioethanol Conversion into Propylene over Various Zeolite Catalysts: Reaction Optimization and Catalyst Deactivation.

Catalytic conversions of bioethanol to propylene were investigated over different zeolite catalysts. H-ZSM-5 (SiO2/Al2O3 = 80) was found to be the most effective for propylene production. Furthermore, H-ZSM-5 (SiO2/Al2O3 = 80) was investigated under different variables of catalytic reaction (calcination temperature, feed composition, reaction temperature, and time on stream) for the conversion of ethanol to propylene. The H-ZSM-5(80) catalysts calcined at 600 °C showed the highest propylene yield. The moderate acidic site on ZSM-5 is required for the production of propylene. The activity on ZSM-5 is independent of the ethanol feed composition. H-ZSM-5 catalyst deactivation was observed, owing to dealumination. The highest propylene yield was 23.4% obtained over HZSM-5(80). Propylene, butene, and ≥C5 olefins were formed by parallel reaction from ethylene. Olefins were converted to each paraffin by sequential hydrogenation reaction. HZSM-5(80) catalyst is a promising catalyst not only for ethanol but also for the conversion of bioethanol to light olefins.

Insights into Promoting Effect of Sm on Catalytic Performance of the CeO2/Beta Catalyst in Direct Conversion of Bioethanol to Propylene

Insights into Promoting Effect of Sm on Catalytic Performance of the CeO2/Beta Catalyst in Direct Conversion of Bioethanol to Propylene

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.

Ethanol dehydration to diethyl ether over ZSM-5 and β-Zeolite supported Ni[sbnd]W catalyst

Diethyl ether is an excellent additive in standard internal combustion engine fuel. The desired reaction product yield is more dependent on the type and strength of acidity of a catalyst for the higher selectivity of diethyl ether or ethylene. In the current work, the chemical process dehydration of alcohol was investigated successfully for forming diethyl ether and alkene over the synthesized tungsten-nickel-loaded catalysts. In present study synthesized different metal-loaded (Ni, W) on different supports (H-ZSM-5, β-Zeolite), and only weak acidic sites catalyst (with and without Ni loaded Zirconium aluminate) and compared all above synthesized catalyst for ethanol dehydration to diethyl ether at 7 h reaction time, 6 wt% catalyst dose, and 230 °C reaction temperature. Characterization using XRD, SEM-EDS, XPS, Raman-spectra, and BET-BJH revealed the appropriate synthesis of the catalyst and uniform Ni and W metal loading, resulting in increased catalytic performance. W-Ni metal oxide loading on H-ZSM-5 shows the most promising results than metal oxide loading on other support catalysts. A 14.61% yield enhanced the desired diethyl ether synthesis due to 1% tungsten metal oxide loading on 5 %Ni-HZSM-5. The XRD, FTIR, and TG-DTA analysis of reused 1 %W-5% Ni-HZSM-5 catalyst provides excellent reusability up to the fifth cycle of use, with a reusability efficiency of more than 96 % even up to the fifth reusability cycle. 1 %W-5 %Ni-HZSM-5 showed the best performance in a batch reactor for maximum diethyl ether synthesis from ethanol dehydration at a given reaction condition.

Direct and Highly Selective Conversion of Bioethanol to Propylene Over Y-CeO2 and Zeolite Beta Composite

Direct and Highly Selective Conversion of Bioethanol to Propylene Over Y-CeO2 and Zeolite Beta Composite

Protective desilication of β zeolite: A mechanism study and its application in ethanol-acetaldehyde to 1,3-butadiene

The conversion of bioethanol to 1,3-butadiene (ETB) is expected to be one of the most promising routes to alternate the petroleum route. However, the preparation of hierarchical β zeolite to serve as the catalyst support is still challenging. In this work, hierarchical β zeolite was prepared through protective desilication by quaternary ammonium hydroxide (TAAOH), and Zr-β zeolite was prepared using the hierarchical β zeolite by dealumination-metallization strategy for ETB reaction. The mechanism of protective desilication was clarified by some control experiments. The protection of TAA+ coexists with OH- attacking and they act in different treating stage, and there lies the best treatment concentration regarding to the mesoporous formation in β zeolite. By adjusting the length of TAAOH alkyl chain, the mesoporosity of β zeolite was tuned successfully. The catalytic activity of Zr-β zeolite was enhanced by the generation of mesoporosity and better capability of coke was achieved which mitigated the deactivation.

Bioethanol Production from Sugarcane Press-Mud: Assessment of the Fermentation Conditions to Reduce Fusel Alcohol

Within a biorefinery context, bioethanol is a promising platform molecule since it can be used as raw material to produce a wide spectrum of valuable industrial products such as H2 and light olefins. However, the presence of impurities limits the conversion of bioethanol in these products. Herein, we aimed to determine the proper pretreatment and fermentation conditions to yield bioethanol with a low content of impurities, such as 3-methyl-1-butanol, by using sugarcane press-mud as feedstock. To do so, a Box-Behnken methodology was employed to select proper pretreatment and fermentation conditions. Factors assessed were temperature, stirring, and pH during fermentation of hydrolysates coming from two different pretreatment methods named as hydrothermal and acid hydrolysis. Results showed that the fermentation temperature should be kept between 26–30 °C to assure at least 91 g/L ethanol. The fusel alcohol content would be reduced by 22% at 30 °C, pH = 4.5, and 200 rpm if sugarcane press-mud is pretreated under acid hydrolysis conditions (T = 130 °C, t = 1 h, 16 g HNO3/kg solid). Further studies should aim to integrate these conditions within a biorefinery concept to yield valuable products such as H2 and ethylene.