Bioethanol Dehydration Research Articles

Developing highly stable and reusable WO3 on mesoporous cellular foam silica for dilute bioethanol dehydration to ethylene

This study developed a highly stable and reusable WO3 on mesoporous cellular foam silica catalyst (MCF-Si) for dilute bioethanol (70%v/v) dehydration to ethylene. WO3/MCF-Si exhibited exceptional performance during reaction, maintaining a high yield of ethylene ranging from 79.6% to 76.3% even in the final cycle over five consecutive cycles (20 h each), operating without requiring regeneration. Characterization of the spent catalyst revealed the preservation of key textural properties and a shift in the acidity profile. The strength of acidity transitioned from weak to strong acidity, while the type of acid sites evolved from Lewis to Bronsted acid sites. However, the remaining acidity remained sufficiently high to promote efficient ethylene production. Additionally, WO3/MCF-Si demonstrated outstanding resistance to coke formation, with a coke content measured below 0.9 wt%. In light of these findings, WO3/MCF-Si emerges as a promising candidate catalyst for developing sustainable processes for converting dilute ethanol to ethylene.

Oriented 1D Metal-Organic Frameworks for Selective Chemisorption by a Substitution-Insertion Mechanism.

Chemisorption on organometallic-based adsorbents is crucial for the controlled separation and purification of targeted systems. Herein, oriented 1D NH2-CuBDC·H2O metal-organic frameworks (MOFs) featuring accessible CuII sites are successfully fabricated by bottom-up interfacial polymerization. The prepared MOFs, as deliberately self-assembled secondary particles, exhibit a visually detectable coordination-responsive characteristic induced by the nucleophilic substitution and competitive coordination of guest molecules. As a versatile phase-change chemosorbent, the MOFs exhibit unprecedented NH3 capture (18.83 mmol g-1 at 298 K) and bioethanol dehydration performance (enriching ethanol from 99% to 99.99% within 10 min by direct adsorption separation of liquid mixtures of ethanol and water). Furthermore, the raw materials for preparing the 1D MOFs are inexpensive and readily available, and the facile regeneration with water washing at room temperature effectively minimizes the energy consumption and cost of recycling, enabling it to be the most valuable adsorbent for the removal and separation of target substances.

Dehydration of bioethanol using novel polysulfone (PSF)/nonionic surfactants hybrid membranes

This study focuses on developing a novel polysulfone (PSF) dense hybrid membrane modified with nonionic surfactants, Tween 20 (T20) and Triton X-100 (X100), for improved pervaporation (PV) dehydration of bioethanol. The modified membranes were then examined for their ethanol dehydration performance, microscopy and spectroscopy characteristics, surface charge, mechanical and roughness properties, crystallinity structure, differential scanning calorimetry (DSC), swelling, and contact angle (CA) analysis. The free volume structure of the membranes was assessed using positron annihilation lifetime spectroscopy (PALS) and Doppler broadening spectroscopy (DBS). A significant discovery from this analysis was the semi antiplasticizing effect observed when surfactants were added to the PV membranes. The PV results revealed that incorporating 0.5 wt% T20 into PSF significantly improved the total flux and PSI of PSF/T20 to 226.35 g/m2 h and 46578 g/m2 h, respectively. Similarly, the total flux and PSI of hybrid membranes containing X100 increased to 110.19 g/m2 h and 43680 g/m2 h. Consequently, the developed PSF/T20 membranes demonstrated more significant potential for bioethanol dehydration compared to PSF/X100 membranes.

Optimization of the bioethanol dehydration process using MgCl2 as mass separating agent

Ethanol derived from lignocellulosic sources is an important chemical that can have several uses such as biofuel that can be blended with gasoline, as sanitizer for the disinfection of surfaces, or as additive in the food, cosmetic and pharmaceutical industry. Nevertheless, its separation poses a challenge because it must be separated from water and this mixture forms an azeotrope. This research focuses on the ethanol dehydration using magnesium chloride (MgCl2) as a mass separating agent, which is an innocuous chemical used in the food industry to process Tofu. Therefore, it does not have any side effect, or it is not harmful for humans. Therefore, the use of this salt makes possible to use the purified ethanol as an additive in the food, cosmetic, or pharmaceutical industry. The proposed separation process is optimized using surrogate nonlinear models for the preconcentration and salt evaporation units. The results showed that using magnesium chloride dodecahydrate is a feasible alternative to bioethanol valorization.

Production of gasohol by azeotropic distillation

AbstractA new azeotropic distillation process is presented to produce gasohol in an adequate concentration of bioethanol and isooctane, which emulates the properties of gasoline ready to use in conventional combustion engines. Since the mixing step is eliminated, there are significant economic savings which imply a competitive price of bioethanol. A comparison is provided with the traditional bioethanol dehydration process, extractive distillation. Both processes were simultaneously designed and optimized with differential evolution with a Tabu list algorithm (DETL) in order to reduce the total annual cost (TAC). Results showed that when obtaining E10 biofuel, a blend of up to 10% ethanol and 90% unleaded isooctane, via azeotropic distillation, over 40% of the TAC is saved compared to obtaining pure alcohol dehydrating through extractive distillation. Moreover, the reduction in carbon dioxide emissions results in an average of 27%.

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.

Unpacking bio-based alternatives to ethylene production in Brazil, Europe, and the United States: A comparative life cycle assessment

Plastics account for 4.5% of global greenhouse gas (GHG) emissions, which are hard-to-abate due to the use of fossil fuels as feedstock. Our study develops a cradle-to-gate life cycle assessment of bioethylene production, exploring 33 pathways across Brazil, the EU, and the US. It aims to understand whether substituting fossil-based ethylene with bioethylene contributes to lowering carbon emissions, and in which of the relevant bioenergy-producing regions/countries the valorisation of biofuels as feedstocks would provide a less carbon-intensive bioethylene production. Results indicate that bioethylene production through catalytic dehydration of sugarcane bioethanol in Brazil presents lowest GHG emission. This pathway could deliver up to −2.1 kg CO2e/kg ethylene when accounting for biogenic carbon storage in long-lived applications such as infrastructure. In contrast, beef tallow performs the poorest as a raw material, regardless of whether land-use change (LUC) emissions are considered. When biogenic carbon storage is factored out, none of the pathways outperforms conventional fossil-based steam cracking; however, some are within the fossil-based range indicating potential indirect benefits through reduced refinery utilisation. Our study underscores that biomaterials production as a climate mitigation strategy must be on par with circular economy measures and the conservation of native forestry ecosystems. These results are particularly relevant to policymakers and industries seeking to align polymer manufacturing with sustainability objectives.

BIOETHYLENE IS A PROMISING SOURCE OF ENERGY AND RAW MATERIALS FOR CHEMICAL INDUSTRY

The modern development of energy, chemical technology and other industrial production sectors is largely focused on processes using renewable raw materials. In the structure of non-traditional energy sources the lion’s share belongs to biomass. The paper provides an prospects assessment for using the available, predominantly solid Ukrainian bioresources, total available amount of which as wood, grain straw and other domestic and industrial organic waste is more than 120 million tons per year, to meet state’s needs both for lubricant and fuel materials and raw materials for chemical industry. A following sequence of transformations for this problem solution were investigated: cellulose of the original raw biomaterial — glucose — bioethanol — ethylene. The option of increasing the effectiveness of the latter stage was considered of obtaining bioethane from bioethanol due to the use of the latest catalysts. The results both physical and computational study of bioethanol dehydration process are given, that allowed to reveal the peculiarities of process kinetics when proposed catalyst using. It is shown that, in addition to reducing energy consumption, the catalyst provides 91 % selectivity for ethylene at ~95 % of the biomethanol conversion rate. The initial data for the design of highly efficient catalytic processes and reactors for the dehydration of bioethanol to ethylene were obtained. Bibl. 20, Fig. 2, Tab. 3.

Toward a Flexible Design for the Bioethanol Dehydration Using Extractive Distillation. Part 1: Steady-State Design and Optimization

Toward a Flexible Design for the Bioethanol Dehydration Using Extractive Distillation. Part 1: Steady-State Design and Optimization

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.

Water‐Stable Metal Azolate Frameworks Showing Interesting Flexibilities for Highly Effective Bioethanol Dehydration

AbstractThe ethanol/water separation challenge highlights the adsorption capacity/selectivity trade‐off problem. We show that the target guest can serve as a gating component of the host to block the undesired guest, giving molecular sieving effect for the adsorbent possessing large pores. Two hydrophilic/water‐stable metal azolate frameworks were designed to compare the effects of gating and pore‐opening flexibility. Large amounts (up to 28.7 mmol g−1) of ethanol with fuel‐grade (99.5 %+) and even higher purities (99.9999 %+) can be produced in a single adsorption process from not only 95 : 5 but also 10 : 90 ethanol/water mixtures. More interestingly, the pore‐opening adsorbent possessing large pore apertures showed not only high water adsorption capacity but also exceptionally high water/ethanol selectivity characteristic of molecular sieving. Computational simulations demonstrated the critical role of guest‐anchoring aperture for the guest‐dominated gating process.

Water-Stable Metal Azolate Frameworks Showing Interesting Flexibilities for Highly Effective Bioethanol Dehydration.

The ethanol/water separation challenge highlights the adsorption capacity/selectivity trade-off problem. We show that the target guest can serve as a gating component of the host to block the undesired guest, giving molecular sieving effect for the adsorbent possessing large pores. Two hydrophilic/water-stable metal azolate frameworks were designed to compare the effects of gating and pore-opening flexibility. Large amounts (up to 28.7 mmol g-1 ) of ethanol with fuel-grade (99.5 %+) and even higher purities (99.9999 %+) can be produced in a single adsorption process from not only 95 : 5 but also 10 : 90 ethanol/water mixtures. More interestingly, the pore-opening adsorbent possessing large pore apertures showed not only high water adsorption capacity but also exceptionally high water/ethanol selectivity characteristic of molecular sieving. Computational simulations demonstrated the critical role of guest-anchoring aperture for the guest-dominated gating process.

Process simulation-based scenario analysis of scaled-up bioethanol production from water hyacinth.

The online version contains supplementary material available at 10.1007/s13399-023-03891-w.

Phosphotungstic acid catalysed bioethylene synthesis under industrially relevant conditions

The catalyst presented in this work can contribute to the development of the sustainable production of ethylene via bioethanol dehydration.

Effects of zeolite frameworks and hierarchical structures on catalytic bioethanol dehydration: In-situ DRIFTS and DFT studies

Herein, the combined in-situ diffuse reflectance infrared Fourier transform spectroscopy and density functional theory studies were employed to investigate the effects of different zeolite frameworks and hierarchical structures on catalytic bioethanol dehydration. The findings reveal that different zeolite frameworks enable the formation of distinct intermediates, hence promoting different mechanistic pathways. Interestingly, the FER is highly selective to ethylene and inhibits the formation of by-products thanks to the confined porous structure of the FER. Although the pristine small pore FER often suffers from fast catalyst deactivation, the incorporation of hierarchical structures in the FER framework can mitigate this significantly. Accordingly, the catalytic stability of the hierarchical FER was improved remarkably with a high ethylene yield (∼95%), whereas the pristine FER suffers from fast deactivation. Additionally, coke formation over the hierarchical FER catalyst was also reduced significantly compared to that of the pristine FER. Importantly, the in-situ DRIFTS studies reveal that the different reaction pathways over hierarchical and commercial FER have been observed in which the hierarchical one promotes the monomeric pathway due to the facile desorption of corresponding products and intermediates, whilst the pristine one promotes bioethanol conversion via both pathways of monomeric and dimeric pathways to produce ethylene and diethyl ether, respectively.

Operability assessment and systematic PI control of a class of Extractive Dividing Wall Distillation Columns: Case of ethanol dehydration

In this work, the practical control capability assessment and the input-output pairing in the design of a control system for a class of Extractive Dividing Wall Distillation Columns is addressed through a parameter called Operability Index. The configured control system is equipped with PI conventional controllers, which all of them are simultaneously and systematically tuned through relationships coming from a pole-stable assignment approach. By considering the bioethanol dehydration as a case of study, known for its difficulty in achieving high purities, the control system’s performance is illustrated. The advantage of this control system design way lies on: (1) the Operability Index smartly provides the physical perception of the control effort that the input will likely perform to cause a change to the related output, (2) a systematic tuning framework that sidestep the typical procedure in distillation columns of tuning the controllers in a sequential way, and (3) the simplest calculations on the basis of the simplest parameters that can be identified in a complex process as a distillation column is: static gains, nominal value of the inputs and the one of the outputs, and settling times.

Toward carbon‐neutral ethylene production: assessment of the application potential of bio‐ethylene production pathways in China

AbstractThe production of bio‐ethylene is a promising way to replace fossil‐based ethylene production, reducing greenhouse gas emissions and working towards China's carbon neutrality goals. This study elaborates on five bio‐ethylene technological pathways: first‐ and second‐generation bioethanol dehydration, direct and indirect thermochemical synthesis, and methanol‐to‐olefins (MTO). It retrieves information about them from commercial patents and the scientific literature, and comprehensively assesses their potential for application in large‐scale ethylene production in China. The techno‐economic feasibility of these five technological pathways is discussed in terms of feedstock availability, investment level, technological development level, and political issues such as the carbon neutrality goal to which China's government is committed. Overall, two pathways (indirect thermochemical synthesis and MTO) exhibited competitive minimum ethylene selling prices at 5243 yuan/t (822 USD t–1) and 6767 yuan/t (1061 USD t–1), respectively, of which both are lower than the average ethylene market price of 7000 yuan/t (1098 USD t–1). In comparison with the conventional fossil‐derived ethylene, bio‐ethylene could decrease carbon emission by 3.2%–15.1% under a scenario of 20% bio‐ethylene substitution in 2019, showing promising potential for decarbonizing the ethylene industry and contributing to the achievement of China's carbon neutrality goals. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.

Tuning the selectivity of cerium oxide for ethanol dehydration to ethylene

Ethylene is a prized raw material in the chemical industry, as well as a valued monomer to produce important commodities. At present, ethylene is mainly produced via the cracking of hydrocarbons, but there is an increasing interest in exploiting renewable biomass-derived feedstocks. The catalytic dehydration of bioethanol is a sustainable alternative route to produce ethylene. Ceria-based catalysts are active for ethanol dehydration to ethylene at low-temperature, but their selectivity is limited by the undesired formation of acetaldehyde. Partially reduced ceria can promote the dehydration of primary alcohols into alkenes over their dehydrogenation to aldehydes. This work provides computational insight into the role of surface oxygen vacancies in the selectivity of ceria. Based on this, it is proposed that the selectivity of ceria toward ethylene can be tuned by substituting Ce4+ with La3+ cations. This is tested using both density functional theory (DFT) calculations and temperature-programmed desorption (TPD) experiments to quantify the impact of doping ceria with lanthanum on the production of ethylene and acetaldehyde. The La-doped ceria sample is found to be more active and selective. This insight can guide the rational design of new ceria-based catalysts for an ethanol dehydration reaction with high selectivity to ethylene.

Process Simulation-based Net Energy Analysis for Future Bioethanol Production as Commercial Biofuel from Waste Rice Straw in Sri Lanka

As the staple food crop in Sri Lanka, paddy rice occupies around 34% (over 0.87 million hectares of land) of the total arable area in the country, corresponding to an average rice production of 3,774,344 t/year. Rice straw is the major biomass waste from rice cultivation, which approximates to an average of 2,830,758 t/year generation at a theoretical straw/grain ratio of 0.75. Open burning of rice straw in paddy fields is the common practice, which could result in an average GHG emissions of 92 kg CO2 eq/t of dry rice straw and other harmful airborne emissions. Application of rice straw into soil as an organic fertiliser is also an inefficient practice, compared to bioenergy generation using rice straw. The average composition of the Sri Lankan rice straw (i.e. 30.0 wt.% cellulose, 3.9 wt.% hemicellulose, 38.2% lignin, 16.1 wt.% wax, and 12.3 wt.% silica) shows the possibility to be used as a second-generation bioethanol feedstock. Existing studies indicate that bioethanol production from rice straw is more environmentally-benign, compared to alternative options, such as gasification for combined heat and power and dimethyl ether (DME) production. This study analyses the net energy indicators of a possible bioethanol production process from rice straw in Sri Lanka. Chemical process simulations using Aspen Plus software were utilised to evaluate the bioethanol production process from rice straw, with a plant output capacity of 1,000 litres/hr of dehydrated bioethanol (99.7 vol.% ethanol) that can be blended with gasoline as a commercial fuel (e.g. E10: 10% bioethanol+gasoline) without any vehicle engine modification. The cradle to gate bioethanol production process from waste rice straw, considered for net energy analysis consists of three major stages: 1. Rice straw preparation, 2. Rice straw transportation, and 3. Bioethanol conversion. The results show that the considered bioethanol production process has a positive net energy gain and increased renewability factor. Detailed analysis indicates that only around 8% of the total process energy consumption is utilised for the bioethanol dehydration operation that is favourable for converting any existing rice straw ethanol plant into commercial gasohol production plant. The sensitivity of bioethanol yield and process energy parameters for the net energy indicator results are further analysed and discussed. The findings from this study can support decision making for a future waste-to-biofuel plant using waste rice straw in Sri Lanka.Keywords: Rice straw, Bioethanol production, Net energy analysis, Process simulation, Waste-to-biofuel

Enhanced bioethanol-to-ethylene performance over nanosized sheet-like M-SAPO-34 (M = Sr and K) catalysts

Two-dimensional (2D) morphology zeolites nanosheets NS-M-SAPO-34 (M = K and Sr) were developed and applied for producing ethylene (C2H4) from bioethanol. Various factors, including SAPO-34 type, temperature, bioethanol concentration, and weight hourly space velocity (WHSV) on C2H4 production were evaluated. The synthesized NS-M-SAPO-34s gave a nanosheet-like morphology with a thickness of 25–50 nm, while the commercial cube-like SAPO-34 (CC-SP34) exhibited a cubic-like morphology with a particle size of about 1.5 μm. The specific surface area of the NS-Sr-SAPO-34 was 644 m2 g−1 which was much larger than that of CC-SP34 (573 m2 g−1). The catalytic performance evaluated by bioethanol dehydration reaction showed that NS-Sr-SAPO-34 exhibited significant improvements not only in suppressed coke deposition (5.6%) and prolonged lifetime (913 min) but also in higher C2H4 yield (94.5%) compared with those (11.8%, 160 min and 82.4%, respectively) of CC-SP34, which can be attributed to the shortened diffusion path length, highly accessible active centers and suitable medium-strong acidity. Elevated temperature, high bioethanol concentration and decreased WHSV tended to enhance the C2H4 yield, while decreased bioethanol concentration was propitious to suppress coking rate. An optimal C2H4 yield of 100% was obtained at 350 °C with a bioethanol concentration from nutrient broths (15 vol%, WHSV = 0.75 h−1).