Ethylene Oxide Production Research Articles

The Performance of Ethylene Partial Oxidation on Group IB Metal Stepped Surfaces

Group IB metal catalysts, particularly Ag, Au, and Cu, exhibit particular selectivity for ethylene oxide (EO) formation, while Ag demonstrating the highest performance so far. Previous studies have explored the EO formation mechanism on (100) and (111) surfaces of group IB metals, but the reaction mechanism on the (211) facet (analogous to the edge sites of a catalyst particle) remains poorly understood. Herein, we fill in the knowledge gap by analyzing ethylene partial oxidation to EO on the (211) surfaces of Ag, Au, and Cu through density functional theory (DFT) calculations, scaling relationship analysis, and microkinetic modeling. Our study demonstrates that the (211) surface decreases the energy barrier for the dissociation of oxygen molecules into oxygen atoms, while unfavorable for the production of EO. Therefore, we should preserve an appropriate concentration of (211) surface on the nanoparticles when designing catalysts for the ethylene epoxidation reaction.

Investigation of the sustainable production of ethylene oxide by electrochemical conversion: Techno-economic assessment and CO2 emissions

Ethylene oxide (EO) is a pivotal intermediate in the chemical industry owing to its versatility and high demand. Currently, direct oxidation is the most important technical process to produce EO. This conventional process, in which ethylene is partially oxidized with air or oxygen, has limited selectivity for EO of 65–90%, leading to significant CO2 emissions. This study explores an alternative method involving the electrochemical selective oxidation of ethylene powered by renewable electricity. The electrochemical oxidation technology is expected to reduce CO2 emitted during EO production. Process models were developed based on existing literature data. A techno-economic evaluation and sensitivity analysis focusing on the electrochemical cell variables were conducted. In this assessment, the investment and production costs of the electro-oxidation process for EO production were compared with those of the conventional process. This assessment also compared processes producing of mono-ethylene glycol and ethylene carbonate from EO. These analyses reveal that the separation energy has a significant impact on the carbon footprint. While current economic and environmental benefits are not favorable, this study identifies key descriptors of the technology for further reducing the carbon footprint. Based on the evaluation results, this study demonstrates the potential to cut CO2 emissions in half compared to conventional plants by utilizing the electro-oxidation of ethylene via a direct route.

Simultaneous process optimization and heat integration for ethylene-to-ethylene oxide process: A surrogate model-based approach

Since the production process of ethylene to ethylene oxide (EO) is highly energy-intensive, it is necessary to perform a whole process heat integration. However, due to the technical barriers, it is always a challenge to design the heat integration system while optimizing the process parameters by mechanistic models. In response to this issue, this study presented a novel surrogate model-based framework that allows for the seamless integration of process optimization and heat exchanger network (HEN) design. The EO production process is modeled and simulated to provide the essential data for surrogate model training. Considering the inherent complexity of the process and the challenges associated with model training, the whole production process is decomposed into parts and the output parameters relevant to heat integration are included within the surrogate models training by Artificial Neural Network. Building upon these preliminary steps, a flexible optimization framework built upon the Genetic Algorithm, integrating the developed process surrogate model and any HEN synthesis model, is constructed to achieve synchronous optimization. The results show that the obtained process saves 22.93 % utility cost and finally leads to a 2.60 % increase in total profit than the alternative designed by the conventional stepwise method, showing the priority of the proposed method.

Economic and environmental insights into the hybrid ethylene oxide production processes

The electrochemical reduction of CO2 into petrochemical precursors is a promising sustainable technology that has the potential to replace conventional processes which utilize fossil fuels. However, compared to primary precursors which are generally analyzed through integrated techno-economic analysis and life-cycle assessment, research on crucial secondary precursors, such as ethylene oxide, is relatively limited. Here, we conducted holistic economic and environmental evaluation for nine potential ethylene oxide production pathways with either CO2 or ethane as the main feed source and compared the profitability and environmental effects of different process alignments. To achieve this, we designed unit processes and combined them to establish pathways for ethylene oxide production. In addition to techno-economic and life cycle analysis, sensitivity analysis was also performed to determine the most important electrochemical parameters, which were identified as the current density and Faradaic efficiency. Finally, we evaluated the influence of carbon credits in relation to target carbon reductions based on stated guidelines for future economic planning. Collectively, the results indicated that the techno-economic feasibility of ethylene oxide production pathways was strongly associated with the feed sources and process configurations. This work demonstrates that conventional ethylene oxide production can be replaced by a more profitable and environmentally-friendly alternative based on combining conventional and electrochemical processes.

CO2-Free Ethylene Oxide Production via Liquid-Phase Epoxidation with Fe2O3/MSM Catalyst.

In this study, we present an approach for ethylene oxide (EO) production that addresses environmental concerns by eliminating greenhouse gas emissions. Our catalyst, Fe2O3/MSM, was synthesized using a hydrothermal method, incorporating Fe2O3 nanoparticles into a well-structured mesoporous silica matrix (MSM). We selected peracetic acid as the oxidant, enabling CO2-free EO production while yielding valuable by-products such as acetic acid, monoethylene glycol, and diethylene glycol. X-ray diffraction (XRD), X- ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) analyses confirmed the heteroatom structure of the catalysts and porosity, while Transmission electron microscopy (TEM) analysis provided insights into its morphology. Then, the synthesized catalyst was used in the liquid-phase epoxidation of ethylene for EO production. Our systematic experiments involved varying critical parameters such as temperature, ethylene to oxidant ratio, catalyst dosage, and solvent to optimize EO selectivity and ethylene conversion. The results of this study demonstrated an 80.2 % ethylene conversion to EO with an EO selectivity of 87.6 %. The production process yielded valuable by-products without CO2 emissions, highlighting its environmental friendliness.

Boosting Electrocatalytic Ethylene Epoxidation by Single Atom Modulation.

The electrochemical synthesis of ethylene oxide (EO) using ethylene and water under ambient conditions presents a low-carbon alternative to existing industrial production process. Yet, the electrocatalytic ethylene epoxidation route is currently hindered by largely insufficient activity, EO selectivity, and long-term stability. Here we report a single atom Ru-doped hollandite structure KIr4O8 (KIrRuO) nanowire catalyst for efficient EO production via a chloride-mediated ethylene epoxidation process. The KIrRuO catalyst exhibits an EO partial current density up to 0.7 A cm-2 and an EO yield as high as 92.0 %. The impressive electrocatalytic performance towards ethylene epoxidation is ascribed to the modulation of electronic structures of adjacent Ir sites by single Ru atoms, which stabilizes the *CH2CH2OH intermediate and facilitates the formation of active Cl2 species during the generation of 2-chloroethanol, the precursor of EO. This work provides a single atom modulation strategy for improving the reactivity of adjacent metal sites in heterogeneous electrocatalysts.

Boosting Electrocatalytic Ethylene Epoxidation by Single Atom Modulation

AbstractThe electrochemical synthesis of ethylene oxide (EO) using ethylene and water under ambient conditions presents a low‐carbon alternative to existing industrial production process. Yet, the electrocatalytic ethylene epoxidation route is currently hindered by largely insufficient activity, EO selectivity, and long‐term stability. Here we report a single atom Ru‐doped hollandite structure KIr4O8 (KIrRuO) nanowire catalyst for efficient EO production via a chloride‐mediated ethylene epoxidation process. The KIrRuO catalyst exhibits an EO partial current density up to 0.7 A cm−2 and an EO yield as high as 92.0 %. The impressive electrocatalytic performance towards ethylene epoxidation is ascribed to the modulation of electronic structures of adjacent Ir sites by single Ru atoms, which stabilizes the *CH2CH2OH intermediate and facilitates the formation of active Cl2 species during the generation of 2‐chloroethanol, the precursor of EO. This work provides a single atom modulation strategy for improving the reactivity of adjacent metal sites in heterogeneous electrocatalysts.

Short Term Silver Electrode Microstructure Changes Under Epoxidation Conditions for Solid Oxide Electrolysis Cells

Ethylene epoxidation is an important reaction forming ethylene oxide (EO), which is a precursor to many other critical chemicals. This study links short-term EO production to the effects on the microstructure of Ag/yttria-stabilized zirconia cells with and without electrochemical promotion of catalysis (EPOC). Nano-scale features, called striations, were observed on the silver under all epoxidation reaction conditions tested, using a scanning electron microscope. While appearing in both cases, the striations for the EPOC case are finer in size (∼150 to 250 nm) compared to the no current case (∼400 to 500 nm). These features did not appear when epoxidation conditions were not present. Striation formation was further linked to the epoxidation reaction through electrochemical impedance spectroscopy and gas chromatography. Ethylene conversion to EO declines over the course of hours as striations form, indicating that striations have a negative influence on the reaction. Distribution of relaxation times was performed to determine the effect striation formation has on the electrochemical performance of the cells. It was observed that the low-frequency peaks in the DRT analysis significantly decrease as striations formed over the course of 10 h.

Patent Analysis of Production of Ethylene Oxide by Pure Oxygen on Methane Ballast

This article is devoted to the consideration of methods for the industrial production of ethylene oxide. Ethylene oxide is produced in large quantities and is primarily used as an intermediate in the production of a number of industrial chemicals, the best known of which is ethylene glycol. The process of producing ethylene oxide is carried out by a direct vapor-phase oxidation process, in which ethylene is oxidized to ethylene oxide by air or oxygen and a silver catalyst at 10-30 atm (1–3 MPa) and 200-300 °C. Ethylene oxidation can be carried out in several ways: air, oxygen under nitrogen ballast, oxygen under methane ballast. The production of ethylene oxide is one of the most dynamically developing. In Russia, the leading place in the production of ethylene oxide is occupied by the enterprise PJSC Nizhnekamskniftekhim. In 2012, the installation for producing ethylene oxide was reconstructed. The reconstruction consisted of transferring the ethylene oxide synthesis stage to methane ballast conditions. A patent analysis was carried out to determine the relevance of this process.

Dispersed Cu (Ni, Co) in MN3 moiety on graphene as active site via electrolytic water towards electro-epoxidation of ethylene

Ethylene oxide (EO) is an important petrochemical product, widely used in printing and dyeing, automotive, medicine, and other fields. Direct epoxidation of ethylene by electrocatalysis is a simple and sustainable route to produce EO, which can avoid the disadvantage of traditional industrial production, such as high temperature and CO2 emissions. An efficient electrocatalyst could generate active oxygen intermediate during the electrolytic water process, which escape from the tremendous activation barrier of breaking molecular oxygen. In addition, ethylene and active oxygen are both required to be adsorbed or produce interaction on the same active site, which is more effective to directly transfer oxygen. Motivated by this strategy, we used first-principle to screen the possibility of 27 single transition metal atoms in MN3 moiety as active site starting from the Gibbs free energy change (ΔG) of *O + C2H4 → *+ C2H4O. Dispersed Cu, Ni, Co can absorb both active oxygen and ethylene, and exhibits the excellent catalytic performance through stability, selectivity, thermodynamics and kinetics evaluation. Electronic structure analysis indicates that the catalytic activity roots from the high electron transfer from the absorbed ethylene to the empty M–O anti-bonding, which weaken the M–O bonding and promote the oxygen transfer. Notably, for CuN3@graphene, the applied potential to produce active oxygen intermediate is 1.53 V vs RHE, and the kinetic energy barrier for subsequent oxygen transfer to form EO is 1.00 eV. This study verified the feasibility of single atomic electrocatalysts for EO production and offers valuable clues to design/discover active center to explore experimentally.

Corrigendum: Life cycle assessment of a novel electrocatalytic process for the production of bulk chemical ethylene oxide from biogenic CO2

Corrigendum: Life cycle assessment of a novel electrocatalytic process for the production of bulk chemical ethylene oxide from biogenic CO2

Techno-economic evaluation of the electrochemical production of renewable ethylene oxide from fluctuating power sources and CO2

We present a techno-economic assessment of a novel ethylene oxide (EO) production process, which converts carbon dioxide (CO2) and water electrocatalytically to ethylene (C2H4) and hydrogen peroxide (H2O2), which are further synthesized into EO. To ensure environmental sustainability, the primary focus was on available CO2 from biogenic sources (biomethane and bioethanol plants) and renewable power sources (wind and photovoltaics) for decentralized applications. Accordingly, data on existing European CO2 and renewable power sources were compiled for spatial analysis to develop technology roll-out and exploitation scenarios: 175 suitable locations were identified. Focusing on three locations, the production costs of EO and the product mix were calculated, considering various energy sources and plant configurations (as of 2030 and 2040). For a generic scenario, considering CO2 to be available free of cost (existing biomethane upgrading) and electricity cost of 36€/MWh, the production cost of the product mix (EO, H2O2, methane, hydrogen) amount to 0.86 €/kg. This is at a similar order of magnitude as assessments on other Power-to-X value chains. Assuming that EO is the only utilizable product, the costs increase to 5.78 €/kg, which is significantly higher than for fossil alternatives. According to the sensitivity analysis, energy efficiency, electricity prices, and capital expenditure are the most relevant factors. Regarding the latter, an extended plant lifetime is a crucial factor.

The electrosynthesis of ethylene oxide in a tandem recycle flow reactor system

In this work an electrochemical tandem recycle reactor was developed for the selective electro-oxidation of ethylene into ethylene oxide with a concentrated product outflow, resulting in an more sustainable pathway towards EO as opposed to the partial oxidation process. The system consisted of (i) a cation exchange membrane equipped module operating at a constant setpoint of 133.3 mA/cm2 and (ii) an anion exchange membrane unit in sequence, with a variable setpoint to regulate the pH. An excess of ethylene was supplied to the porous anode of the cation exchange module, which subsequently reacted with evolved bromine into 2-bromoethanol. As a result the anolyte acidified, which in turn promoted a selective bromine production. The anion exchange module also contributed to the Br2 production, converted 2-bromoethanol into ethylene oxide and neutralized the anolyte. The system underwent equal charge experiments in varied anolyte concentrations with a (i) Ni gauze cathode and an IrO2 coated Ti anode in the cation exchange module and (ii) graphite electrodes in the anion exchange unit. For experiments of 6 up to 10 h, Faradaic efficiencies towards ethylene oxide of 80.2 ± 6% and 46.7 ± 4.5% were sustained in 0.5 M and 3 M KBr anolyte respectively. The reduced selectivity in augmented KBr concentrations was predominantly caused by organochemical thermodynamics, which provoked an increased 1,2-dibromoethane production. The highest ethylene oxide production was achieved in a 0.5 M KBr condition, i.e. 10 g/L, which is ten times higher than the maximum reported figure in literature. In terms of stability, pretreated anodes, i.e. baked at 450 °C in air prior to testing, showed no degradation before and after testing on SEM-EDS analyses, whereas untreated structures were susceptible to corrosion.

Enhanced reinforcement learning in two-layer economic model predictive control for operation optimization in dynamic environment

Economic model predictive control (EMPC) has attracted an abundance of interest in both academic and industrial communities in recent years because it is able to increase the economic profits of dynamic systems. For greater computational efficiency, two-layer EMPC schemes are applied in some complex process control. However, the performance of two-layer EMPC is significantly influenced by the accuracy of the chosen process model. Reinforcement learning (RL) has been studied as a model-free strategy of model-based control approaches, but its safety and stability remain a concern. In order to estimate the model parameters of nonlinear dynamic systems in real time, this work introduces a unique scheme for merging two-layer EMPC and RL. In this scheme, the two-layer EMPC technique maintains closed-loop stability and recursive feasibility while operating the closed-loop dynamic system optimally. And the RL agent continually compares the observed states to the predictions made by the EMPC and modifies the time-varying parameters as necessary. The usability of the proposed scheme is shown on a chemical process of ethylene oxide production in dynamic environment. This work enables online and continuous control, optimization, and model correction, and makes process production optimization more feasible and profitable.

A Cyber-Physical monitoring and diagnosis scheme of energy consumption in Plant-Wide chemical processes

In the large-scale plant-wide chemical process, energy monitoring and diagnosis have a great impact on energy management and sustainable development. Most monitoring and diagnosis methods focused on the construction of the global model with process data, regardless of the meaningful process knowledge and in-depth analysis. Due to the multi-dimensional, correlative, and uncertain characteristics of the collected industrial data, it is laborious to obtain accurate and reliable energy monitoring and diagnosis results. To address these problems, a novel cyber-physical energy monitoring and diagnosis scheme is proposed in this paper. This scheme constructs a cyber-physical model based on process knowledge and data to describe the cause-effect relationships among the energy variables. For energy monitoring, a distributed monitoring approach is developed for energy state estimation based on the constructed monitoring statistics in both variable and residual spaces. For energy diagnosis, a faulty contribution degree index is further addressed and the corresponding root cause location strategy is discussed. The effectiveness and practicality of the proposed scheme are demonstrated via a numerical simulation example and practical ethylene oxide production. Two preset simulated faults and one practical process fault are used and all the abnormal states and root variables are monitored and diagnosed by the proposed scheme. The energy monitoring and diagnosis results provide great support for energy management and development in large-scale chemical plants.

Short Term Silver Electrode Microstructure Changes Under Epoxidation Conditions for Solid Oxide Electrolysis Cells

Ethylene epoxidation is an important reaction to form ethylene oxide (EO), which is a precursor to many other critical chemicals. This study links short-term EO production to the effects on the microstructure of Ag/yttria-stabilized zirconia cells with and without an electrochemically promoted catalyst (EPOC). Nano scale features called striations were observed using a Scanning Electron Microscope (SEM) on the silver under all reaction conditions tested. While appearing in both cases, the striations for the EPOC case are finer in size (~150 to 250 nm) compared to the no current case (~400 to 500 nm). These features did not appear when epoxidation conditions were not present. Striation formation was further linked to the epoxidation reaction through electrochemical impedance spectroscopy (EIS) and gas chromatography (GC). Ethylene conversion to EO declines over the course of hours as striations form, indicating that striations have a negative influence on the reaction. Striation formation further effected the electrochemical performance of the cells, resulting in the low frequency depressions observed in EIS to shrink in both cases after 10 hours of epoxidation.

Ozonative epoxidation of ethylene: A novel process for production of ethylene oxide

Here we report a novel reaction for ethylene oxide production using catalytic reaction of ethylene with ozone at room temperature. A key aspect of this path is boosting selective oxygen coverage on the surface of the catalyst which enables achieving high ethylene oxide selectivity and maintaining high conversion. Comparing the structural changes of the catalyst before and after the reaction suggested that the process allows facile generation of the catalytic active sites and selective oxygen species on the Ag/Al2O3 catalyst. With this novel process and under kinetically controlled regime, single-pass ethylene conversion of 98% and selectivity of 56% were achieved at room temperature. The low apparent activation energy of 22.1 kJmol-1 indicated the feasibility and high rate of this reaction at room temperature. This approach is believed to deliver a new class of processes for other oxygen insertion reactions.

Modelling and control of a bio-ethylene production process

Ethylene is one of the most consumed products in the world, as it has many uses such as the production of nylon from its polymeric compound, the production of vinyl chloride, which is polymerized to polyvinyl chloride for the production of plastics, the production of ethylene oxide, used as a ripening agent for fruits, etc. The conventional method adopted in the production of ethylene is by steam cracking of naphtha at high temperatures. Naphtha is a hydrocarbon, so when cracked, it releases harmful carbon dioxide (CO2) into the atmosphere, and this brought about looking for alternative methods of producing ethylene. As discovered, ethylene can be produced by catalytic dehydration of ethanol, but the main limitation of this process is that the purity of ethylene produced by this approach may not be up to the desired polymer grade of 99.97%. As such, this work has been carried out to model, with the aid of Aspen Plus, and develop control techniques that would enable the process to meet up with the desired output maximum purity from the distillation column (100% ethylene at the top product of the distillation column). In line with that, P-only, PI, and PID controllers tuned with the Tyreus-Luyben technique, Zeiger-Nichols method, and a modified Tyreus-Luyben approach have been used for the control of this process. It was discovered that the PID controller tuned with the modified Tyreus-Luyben parameter had the lowest Integral Absolute Error (IAE) of 1.474 and Integral Time Absolute Error (ITAE) of 4.767 and, hence, it was found out that it could be adopted for proper control of this process, although limited to small upsets caused by disturbances in the system. It is, therefore, recommended that the PID control system developed should be applied on a physical set-up plant to study its real effect.

CO2 free production of ethylene oxide via liquid phase epoxidation of ethylene using niobium oxide incorporated mesoporous silica material as the catalyst.

Ethylene Oxide (EO) is an essential raw material used in various consumer products like different glycol derivatives, ethoxylates, and polymers. We hydrothermally synthesize niobium oxide incorporated with mesoporous silica material (Nb/MSM), an efficient catalyst for CO2 free-ethylene oxide (EO) production via partial oxidation of ethylene. The structural properties of Nb/MSM catalysts were characterized using XRD, TEM, and N2 adsorption-desorption. The catalytic activity of synthesized materials in liquid phase epoxidation (LPE) of ethylene was evaluated in the presence of peracetic acid (PAA) as an oxidant to avoid the production of CO2 and also minimize metal leaching. GC chromatography was used to investigate the successful production of EO, and a peak with a retention time (RT) of 9.01 min served as confirmation. Various reaction parameters viz. temperature, catalyst concentration, ethylene to PAA molar ratio, and solvent effect were investigated in order to optimize the reaction conditions for enhancing the ethylene conversion and selectivity for EO production. By this approach, the challenges of greenhouse gas production and metal leaching were addressed which were associated with previously reported catalysts.

Development of a chromium oxide loaded mesoporous silica as an efficient catalyst for carbon dioxide-free production of ethylene oxide.

Ethylene oxide (EO) is a significant raw material used in many commodities for consumers, particularly ethoxylates, polymers, and certain other glycol derivatives. We synthesized a catalyst by incorporation of chromium oxide into a mesoporous silica material (Cr/MSM) via the hydrothermal method, an effective catalyst for partial ethylene oxidation for producing carbon dioxide (CO2) free EO. Subsequently, XRD, BET, XPS, and TEM were used to analyse the structural characteristics of the Cr/MSM catalyst. The catalytic performance of the synthesized catalyst was assessed in the liquid-phase epoxidation (LPE) of ethylene, utilizing peracetic acid (PAA) as an oxidant. This approach not only circumvented the generation of CO2 but also mitigated the risk of metal leaching. Confirmation of the successful production of EO was achieved through GC chromatography, where the presence of a peak with a retention time (RT) of 8.91 minutes served as conclusive evidence. We systematically explored a range of reaction parameters, including temperature, catalyst concentration, the molar ratio of ethylene to PAA, and solvent effect. This comprehensive investigation aimed to fine-tune the reaction conditions, ultimately improving ethylene conversion and enhancing the selectivity of the catalyst for EO production. This approach can effectively resolve the issues of greenhouse gas emissions and metal leaching that had been associated with previously reported catalysts.