Steam Cracking Research Articles

On‐Purpose Production of Light Olefins Through Oxidative Dehydrogenation: An Overview of Recent Developments

AbstractProducts made from light olefins play an important role in our daily lives. Traditional light olefins production based on steam cracking and fluid catalytic cracking suffer from high energy consumption and CO2 emissions. Thereby, the continually increasing demand for light olefins needs to be met through more environmentally sustainable procedures. On‐purpose production routes are preferred choice among petrochemicals manufacturers, being energy efficient and having lower carbon footprint. Among them, oxidative dehydrogenation (ODH) of light paraffins is a thermodynamically favourable exothermic process as compared to non‐oxidative routes. They can be operated at lower temperatures and have propensity of low coke deposition on catalyst, thereby resisting rapid catalyst deactivation. Herein, we have analysed various catalytic systems utilised in the oxidative dehydrogenation process. We have reviewed role of support, chemical composition of catalyst, presence of dopant, oxidation state of active metal, controlled surface modification by oxidative and reductive pretreatments, and reaction factors for each system. The performance of various catalytic systems for ODH of ethane, propane and butane in the presence of O2, CO2, N2O and special oxidants have been reviewed. A short critical overview on emerging on‐purpose routes for the production of renewable 1,3 butadiene has also been discussed.

High temperature pyrolysis of sewage sludge: Synergistic effects of co-pyrolysis with rice straw and composite plastics wastes

The synergistic effect of co-pyrolysis for the mixtures of sewage sludge (SS), rice straw (RS) and composite plastic wastes (PE&PP) has been investigated with the aim of high gas yields and hydrogen generation. In this context, the applicability of high temperature pyrolysis technology was evaluated at both rotary type batch reactor and rotating screw type continuous reactor operating under the industrially relevant conditions. Gas yields have been improved at increasing the operating temperatures up to 850 °C. The gas yield of 75.06 % with its H2 portion of 32.35 % has been achieved as the best results for continuous pyrolysis unit at pilot scale. Secondary reactions such as steam de-alkylation, steam cracking, water gas shift and so on were regarded as being responsible for the high gas yields when the primary products of pyrolysis, i.e. condensable vapors, were much exposed to the hot zones inside the reactor. The dehydration of organic components involving the loss of water may supply steam to create a reactive pyrolysis atmosphere. While the pyrolysis of sewage sludge and rice straw favors CO and CO2 formation due to the high oxygen contents of these feedstocks, more methane and light olefins were produced when the plastics were added to the feedstock blends. This was ascribed to the initially generated radicals from the decomposition of sewage sludge and/or rice straw that might promote the scission reactions of plastics towards volatiles. It was shown that high temperature pyrolysis can be applied to a variety of organic wastes such as rice straw, sewage sludge and waste plastics. Conversion of wastes to hydrogen fosters the circular economy by putting the disposal costs down and creates a new route on renewable hydrogen generation.

On the Role of Anions in Solid Catalysts with Ionic Liquid Layer (SCILL) for the Selective Hydrogenation of Highly Concentrated Acetylene Streams.

Electric plasma assisted pyrolysis of methane represents a highly promising greener alternative to produce ethylene from biogas and renewable energies compared to conventional steam cracking of naphtha. The mediocre performance of typical Pd-Ag catalysts for the downstream purification of the substantially higher concentrated acetylene impurities (≥15 vol.-%) in those ethylene streams via selective hydrogenation is yet limiting economic interest. Following the concept of solid catalysts with ionic liquid layer (SCILL), we have modified an intrinsically non-selective palladium catalyst with imidazolium based ionic liquids varying among 10 different anions and investigated them in this reaction. The best performing [C4C1IM][MeSO4]-SCILL reaches an outstanding average ethylene selectivity over 20 h on-stream of 82 % at full acetylene conversion without any sign of deactivation, clearly outperforming conventional Pd-Ag catalysts. By varying parameters like ionic liquid (IL) loading, temperature, feed gas composition, cations, and by using XPS for surface analysis we could gain a very comprehensive understanding of the underlying mechanisms that reduce the competing over-hydrogenation and oligomerisation side-reactions.

Steam cracking in a semi-industrial dual fluidized bed reactor: Tackling the challenges in thermochemical recycling of plastic waste

Steam cracking is an integral process in the plastic manufacturing industry. Conventional steam crackers are tubular reactors and use fossil-based feedstocks like naphtha and LPG. This work presents steam cracking in a dual fluidized bed (DFB) reactor as an alternative for the direct steam cracking of plastic waste. Experiments were performed on a semi-industrial DFB system using naphtha, clean polyolefins, real-life plastic wastes, and a polyolefin-derived pyrolysis oil. The results show that steam cracking in a DFB is fundamentally equivalent to steam cracking in tubular reactors. Selective production of light olefins and monoaromatics was achieved within a temperature range of 700–825 °C. Naphtha yielded up to 56 % light olefins and 7 % BTXS, with ethylene and BTXS production positively correlating with cracking severity, while C3 and C4 olefins show a negative correlation. These results confirm that the established steam cracking mechanisms also apply to large-scale DFB steam crackers. The yield of light olefins is consistently obtained at approximately 52 % relative to the polyolefin content of the feedstock, regardless of the non-polyolefin content. This highlights the DFB steam cracker’s ability to produce light olefins directly from plastic waste without presorting. However, steam cracking in DFB results in significantly higher CO and CO2 yields than conventional steam cracking, especially with feedstocks containing non-polyolefins like PET and cellulose. Additionally, steam cracking of an olefin-rich pyrolysis oil yields up to 50 % light olefins with minimal coke formation, highlighting the potential in processing plastic waste pyrolysis oils without pretreatment steps such as distillation and hydrotreatment.

Comprehensive technical analysis of post-combustion carbon capture and storage based on monoethanolamine absorption for petrochemical industry in Indonesia

Abstract The implementation of carbon capture and storage in the petrochemical industry is one of the means of decarbonization. This research focuses on a comprehensive technical analysis of the deployment of post-combustion carbon capture and storage based on monoethanolamine absorption in the petrochemical industry. The olefin complex petrochemical industry in Tuban, Indonesia, is the basis for the analysis, which includes a steam cracker, polyethylene, polypropylene, and raw pyrolysis gasoline hydrotreating units, with capacities of 1000, 940, 600, and 570 kilotons/year, respectively. The total energy consumption is about 16 024.53 GJ/h, and the CO2 emissions are about 1.6 megatons/year. Based on these plant systems, comprehensive technical analyses of the implementation of carbon capture and storage in that industry were performed using Aspen HYSYS® simulation software. Sensitivity analysis was carried out to determine the total CO2 captured, energy intensity, monoethanolamine consumption, and net CO2 captured in various scenarios based on the number of absorber column stages, absorption pressure, and desorption temperature. The CO2 storage site is about 100 km away and is transported by an onshore pipeline with a supercritical phase of CO2. The optimal net CO2 capture value is achieved by setting up a 50-stage absorber column with a pressure of 1 barg and a temperature of 110°C at the top of the desorber column, resulting in a CO2 capture yield of 86.4% and an energy intensity of 12.6 GJ/ton CO2. Under these conditions, the net CO2 captured in the scenario based on gas power plants’ electricity is 0.225 megatons/year, while in the scenario based on gas power plants incorporating 30% biomass electricity, it is 0.544 megatons/year. With increased use of renewable energy in carbon capture and storage facilities, more net CO2 is captured. This study can be applied to various cases of post-combustion carbon capture and storage implementation in the industrial sector, especially in the petrochemical industry.

Molecular simulations and deep neural networks‐based interpretable machine learning modelling of reverse adsorptive MOFs for ethane/ethylene separation

AbstractThe thermal decomposition of ethane (C2H6) and the steam cracking of fossil fuels are the main sources of ethylene (C2H4). However, it usually contains 5%–9% of C2H6 residue, which must be reduced to ensure its utilization during polymerization. C2H6 and C2H4 have comparable kinetic diameters and boiling points (C2H6: 4.44, 184.55 K; C2H4: 4.16, 169.42 K), which makes the separation process very difficult. This contribution employs a methodology that integrates machine learning (ML) with Monte Carlo simulations to evaluate the ddmof database to develop a predictive model for separating ethane (C2H6) and ethylene (C2H4). The ML model's input is the metal–organic frameworks (MOFs) chemical and structural descriptors. The grand canonical Monte Carlo (GCMC) simulations in RASPA software were carried out to calculate the equilibrium adsorption of ethane and ethylene. Different ML models such as random forest, decision tree, and deep neural network models have been tested to estimate the selectivity and ethane uptake from the MOF data being generated. Interpretable ML model using SHapley Additive exPlanations (SHAP) is developed for the better understanding of the impact of the parameters on selectivity and ethane uptake. A user‐friendly graphical user interface (GUI) is presented, allowing users to predict the ethane uptake and selectivity of MOFs simply by entering the values of chemical and structural descriptors.

(Invited) CO2-Negative Ethylene Via Electrolysis – Greenerene™, a Green Chemistry Start-up

Reduction of greenhouse gases is vital for the long-term environmental health of the planet. While there has been progress in reducing and capturing CO2 emissions, a vast majority of emissions are not captured, and atmospheric CO2 concentration continues to rise. This creates a large and growing market for CO2 sequestration and utilization, which presents an opportunity to rethink how commodity chemicals, which often come with a large carbon footprint, are produced in the US and globally. C2H4 is a key building block in the chemical industry to produce a wide range of plastics, solvents, cosmetics, etc. On average, the production of 1 MMT of C2H4 generates 1.5 MMT of CO2, from fuel combustion, decoking, and utilities. Globally, C2H4 production by steam cracking is ranked as the second-largest contributor of energy consumption (2.8 EJ/year) and greenhouse gas emissions (300 MMT of CO2-e/year) in the chemical industry. Electrochemical CO2 reduction reaction (CO2RR) to produce C2H4 at ambient conditions, when coupled with renewable electricity, could reduce dependence on fossil fuels and decarbonize the chemical sector associated with C2H4 production.At Giner, we are developing technology to improve selectivity, productivity, and durability of the CO2 electrolyzer, enabling commercial deployment. This technology is the basis of a spin-out start-up company called Greenerene™ that is currently seeking investment funding to scale up to the pilot plant scale over the next 3-5 years. Currently, our state-of-the-art electrolyzer has achieved 60% C2H4 selectivity at 500 mA cm-2 and 3 V in a 50 cm2 MEA electrolyzer. We are in the process of translating this performance into multi-cell stacks and larger-area cells to enable 1-ton/day production of ethylene at the pilot scale.We have also developed a detailed Techno-Economic Analysis of our technology, including cost of carbon capture, renewable electricity, and balance of plant including power electronics, recirculation, and purification systems, that demonstrates a pathway to economic competitiveness. With the addition of already implemented and anticipated carbon credits, at scale our technology should be able to produce ethylene at less than current market prices, and with significant environmental and climate benefits compared with current production methods. Acknowledgement: The project is financially supported by the Department of Energy’s Office of EERE under Grants DE-EE000942l and DE-EE0010836.

Chemical upcycling of polyolefins into liquid refinery feedstock from the circularity and chemical engineering aspects

Three quarters of all plastics produced each year are discarded to landfill after a single use without proper waste management practices, causing a global environmental crisis: waste plastics suffocating our world at enormously large volumes. Discarding plastics into landfill, inefficiently processing them to lower value materials, or incinerating them cause an irreversible loss of the stored energy in plastics. These plastics, however, represent a tremendous resource for the production of chemicals and can be upcycled into high-quality value-added refinery feedstock that could be used to produce virgin polyolefins. In this article, we review pyrolysis and hydrogenolysis based chemical transformations to convert waste polyolefins into liquid hydrocarbons with a special emphasis on life cycle assessment (LCA), reactor technologies, and integration to existing refineries. Several patented technologies are described in detail to shed a light on engineering aspects of the chemical recycling. Liquid products obtained from chemical recycling are examined from the circularity point of view. Feedstock and stream locations in existing refineries and around steam crackers are recommended to feed and/or blend the products obtained from chemical recycling of polyolefins. Challenges, perspectives, and emerging areas of research and engineering are mentioned.

Ethylene Electrosynthesis via Selective CO2 Reduction: Fundamental Considerations, Strategies, and Challenges

AbstractThe electrochemical carbon dioxide reduction reaction (CO2RR) is a promising approach for reducing atmospheric carbon dioxide (CO2) emissions, allowing harmful CO2 to be converted into more valuable carbon‐based products. On one hand, single carbon (C1) products have been obtained with high efficiency and show great promise for industrial CO2 capture. However, multi‐carbon (C2+) products possess high market value and have demonstrated significant promise as potential products for CO2RR. Due to CO2RR's multiple pathways with similar equilibrium potentials, the extended reaction mechanisms necessary to form C2+ products continue to reduce the overall selectivity of CO2‐to‐C2+ electroconversion. Meanwhile, CO2RR as a whole faces many challenges relating to system optimization, owing to an intolerance for low surface pH, systemic stability and utilization issues, and a competing side reaction in the form of the H2 evolution reaction (HER). Ethylene (C2H4) remains incredibly valuable within the chemical industry; however, the current established method for producing ethylene (steam cracking) contributes to the emission of CO2 into the atmosphere. Thus, strategies to significantly increase the efficiency of this technology are essential. This review will discuss the vital factors influencing CO2RR in forming C2H4 products and summarize the recent advancements in ethylene electrosynthesis.

Characterization and impact of oxygenates in post-consumer plastic waste-derived pyrolysis oils on steam cracking process efficiency

Mechanical recycling of mixed packaging waste has limitations due to challenging separation into pure polyolefin streams which often leads to low quality recyclates. A solution to improve overall recycling rates of polyolefins is chemical recycling. One promising approach is conversion into a liquid product via pyrolysis and subsequent steam cracking of the pyrolysis oil towards light olefins. In this study, distilled fractions of pyrolysis oils from PE and PP-rich waste were characterized via GC × GC including normal and reversed-phase column configurations with a special focus on oxygenated components. Distilled pyrolysis oils were subsequently steam cracked in 20/80 weight‐based blends with conventional naphtha. All pyrolysis oil samples contained substantial amounts of oxygenates (1–10 wt%) which poses a huge challenge for steam cracker feedstocks and it was found that ketones are the most prevailing oxygenate group. Steam cracking experiments showed slightly increased ethylene yields of the blends compared to pure fossil naphtha, with the PE-derived samples outperforming the PP-derived samples. Furthermore, diesel-range distillation cuts led to higher formation of heavy products compared to the naphtha-range cuts. Increased formation of CO was observed as a consequence of the substantial oxygen contamination which can be a deal-breaker in industrial steam crackers. This work shows that distilled pyrolysis oils with conventional naphtha are promising steam cracking feedstocks if intermediate processing steps are performed to remove the oxygenates and other impurities using, for instance, hydrotreatment. With the findings of this work, such upgrading processes can be designed in a more effective way.

Coke Formation in Steam Cracking Reactors: Deciphering the Impact of Aromatic Compounds and Temperature on Fouling Dynamics

Coke Formation in Steam Cracking Reactors: Deciphering the Impact of Aromatic Compounds and Temperature on Fouling Dynamics

Optimized separation of C2H2 from binary mixtures of C2H2/CO2 and C2H2/C2H4 by coordinative copper(I) metal nodes modified from HKUST-1

Acetylene (C2H2), an industrially important gas, is produced by steam cracking of hydrocarbons and inevitably contains traces of ethylene (C2H4) and carbon dioxide (CO2) as impurities. Metal-organic frameworks (MOFs) and further post-modified MOFs are versatile and promising adsorbents for energy-efficient C2H2/C2H4 and C2H2/CO2 separation by selective adsorption of C2H2 compared to energy-consuming conventional methods. Herein, Cu(I) ion generated structures from post-synthetic modification of HKUST-1 are chosen as C2H2 selective sites over both C2H4 and CO2 gases. Protective Cu(I) ions were generated by post-coordinative reduction of Cu(II) nodes of a HKUST-1 using hydroquinone as a reducing agent to create robust C2H2 adsorptive sites. In the metal node reduced to Cu(I) by hydroquinone (HKUST-1-HQ), C2H2 selectivity was enhanced not only for C2H2/CO2 but also C2H2/C2H4 by the presence of the Cu(I) site, by virtue of the copper(I)-alkynyl chemistry. In a breakthrough test, separation of C2H2 and C2H4 did not occur at the coordinatively unsaturated site (HKUST-1), whereas separation capability appeared after monovalent copper was introduced. Enhanced C2H2/CO2 separation was also observed for HKUST-1-HQ. The adsorption behavior of C2H2 (triple bond), C2H4 (double bond), and CO2 (opposite quadruple moment) at the copper(II) open metal site and copper(I) site originating from the same structure respectively is studied to understand the C2H2 gas sorption. In HKUST-1-HQ, the study of four types of possible Cu structures (Nodes II, III, IV, and V) and adsorbates revealed that Node IV is a preferential site over the other three sites, and the CUS site (bare HKUST-1). DFT computational simulation successfully demonstrated that the Node IV type Cu(I) is a plausible adsorption site for C2H2. Overall, HKUST-1-HQ exhibits greater moisture stability, improved selectivity, and repeatability as C2H2 adsorbent.

Molecular-Level Kinetic Model for Light Hydrocarbon Steam Cracking Based on the SU-BEM Framework.

In this work, a molecular-level kinetic model of ethane/propane steam cracking was developed by using a hybrid structural unit-bond electron matrix framework. The molecular-level simulation was conducted, creating a detailed feedstock composition, formulating the reaction rules, and automating the generation and visualization of reaction networks. Ordinary differential equations were automatically generated based on the Arrhenius equation, while the kinetic parameters were reduced via linear free energy relations (LFERs). Furthermore, proper mathematical models for mass transfer, heat transfer, and momentum transfer within the cracking furnace were integrated into the molecular-level kinetic model, enabling the simultaneous calculation of the transfer process and chemical kinetics in steam cracking. The model was validated by its precise prediction of product yields, outlet pressure, and outlet temperature, which were collected from an industrial gas-cracking furnace.

Unlocking naphtha from polyolefins using Ni-based hydrocracking catalysts

Naphtha (C5-C12 alkanes) is a platform feedstock in the petroleum industry and an ideal target for reutilizing plastic waste at scale. Hydrocracking has emerged as a promising technology for deconstructing polyolefins to naphtha. However, contemporary catalysts rely on Pt to achieve high rates, while earth-abundant metals (EAM) perform poorly. Herein, we develop high-performance Ni/BEA catalysts for polyolefin hydrocracking, achieving complete low-density polyethylene (LDPE) deconstruction with 80 % maximum naphtha yield within 12 h at 250 °C, 60 bar H2, and a catalyst-to-polymer ratio of 1:100. These catalysts are versatile, accommodating virgin resins and commercial polymer products, and are directly reusable and regenerable. Comparative analysis highlights that 5Ni/BEA(25) exhibits the highest naphtha productivity of 11.4 gNaphthagcat∙h, surpassing previously reported Pt- and EAM-based catalysts by 2.5–6.2x. Technoeconomic and life-cycle analyses reveal naphtha from LDPE hydrocracking is economically and environmentally competitive to fossil-fuel-derived naphtha. These advancements pave the way for the industrial implementation of earth-abundant Ni-based catalysts in polyolefin hydrocracking, followed by retrofitting steam crackers to address plastics waste at scale.

Steam cracking of sulfur containing compounds: A fundamental modelling study

Sulfur-containing additives are commonly used in industrial steam cracking to mitigate carbon monoxide (CO) formation. Their impact on solid coke deposition in reactors is well-studied but not fully understood. This study investigates the decomposition of five common sulfur compounds (DMDS, DMS, DMSO, CS2, COS) in both inert and hydrocarbon environments within the steam cracking industry. To achieve this, an in-house automated network generation tool called Genesys and a validated ab initio methodology at the CBS-QB3 level are used. This combination generates a comprehensive kinetic model with precise thermodynamic and kinetic parameters. The kinetic model is rigorously validated against experimental data from prior studies under various conditions, including inert nitrogen atmospheres and hydrocarbon matrices (using ethane and heptane). Experimental setups involve bench-scale annular quartz reactors and pilot-scale stainless steel reactors. Remarkably, the kinetic model accurately predicts primary products and captures secondary product trends across diverse conditions without parameter adjustments. Rate of production analyses reveal critical decomposition pathways during sulfur-containing additive pyrolysis and the influence of hydrocarbon matrices. Notably, these additives primarily yield H2S upon decomposition, with CS2, SO2 and thiophene as minor products. In conclusion, the developed fundamental kinetic model accurately predicts product formation during the pyrolysis of DMS, DMDS, DMSO, CS2 and COS, whether in nitrogen or a hydrocarbon matrix, without altering core thermodynamic and kinetic parameters.

Investigation of AFeO3 (A=Ba, Sr) Perovskites for the Oxidative Dehydrogenation of Light Alkanes under Chemical Looping Conditions.

Oxidative dehydrogenation (ODH) of light alkanes to produce C2-C3 olefins is a promising alternative to conventional steam cracking. Perovskite oxides are emerging as efficient catalysts for this process due to their unique properties such as high oxygen storage capacity (OSC), reversible redox behavior, and tunability. Here, we explore AFeO3 (A=Ba, Sr) bulk perovskites for the ODH of ethane and propane under chemical looping conditions (CL-ODH). The higher OSC and oxygen mobility of SrFeO3 perovskite contributed to its higher activity but lower olefin selectivity than its Ba counterpart. However, SrFeO3 perovskite is superior in terms of cyclic stability over multiple redox cycles. Transformations of the perovskite to reduced phases including brownmillerite A2Fe2O5 were identified by X-ray diffraction (XRD) as a cause of performance degradation, which was fully reversible upon air regeneration. A pre-desorption step was utilized to selectively tune the amount of lattice oxygen as a function of temperature and dwell time to enhance olefin selectivity while suppressing CO2 formation from the deep oxidation of propane. Overall, SrFeO3 exhibits promising potential for the CL-ODH of light alkanes, and optimization through surface and structural modifications may further engineer well-regulated lattice oxygen for maximizing olefin yield.

Ethylene and propylene production from steam cracking in Europe: a consequential perspective

Ethylene and propylene production from steam cracking in Europe: a consequential perspective

Effect of Reactor Alloy Composition on Coke Formation during Butane and Ethane Steam Cracking

Effect of Reactor Alloy Composition on Coke Formation during Butane and Ethane Steam Cracking

Method development and evaluation of product gas mixture from a semi-industrial scale fluidized bed steam cracker with GC-VUV

Steam cracking in fluidized beds offers an alternative to conventional steam cracking for sustainable hydrocarbon production. This approach has gained interest, particularly in the context of recycling plastics to generate valuable hydrocarbons. Integrating this process into existing petrochemical clusters necessitates a thorough characterization of the products derived from this new feedstock. This work focuses on addressing the challenges associated with species quantification and characterization time for assessing the product mixture resulting from a steam cracking process. The experiments were conducted in a semi-industrial scale dual fluidized bed steam cracker, utilizing polyethylene as the feedstock. To sample species spanning from C1 to C18, cooling, scrubbing, and adsorption were introduced. These steps were integrated with GC-VUV (Gas Chromatography with Vacuum Ultraviolet Spectroscopy) and other widely recognized analytical methods to quantify the sampled species. The primary focus was on GC-VUV analysis as a suitable characterization method for identifying and quantifying C4 to C18 species, which can constitute up to 35% of the product mixture obtained from polyethylene steam cracking (750 °C to 850 °C). Quantifying C6 to C18 hydrocarbons becomes the time-critical step, with GC-VUV potentially achieving this in 1/6th of the analysis time and with relatively optimal quantification compared to the traditional characterization methods.

A Comprehensive Assessment of Conventional Petrochemicals and Bio-based Alternatives in Polymer Production

This research explores the environmental impact of propylene production, especially conventional polypropylene (PP) which constitutes 16% of the global plastic industry. The production methods, including steam cracking and fluid catalytic cracking, significantly contribute to both greenhouse gas emissions (28%) and fossil resource use (23%). In response, the paper advocates for a transition to bio-polypropylene, foreseeing global market growth from $94.8 million in 2021 to $996.9 million in 2028, with a compound annual growth rate of 39.9%. Bio-polypropylene offers a reduced carbon footprint and better alignment with production sustainability goals. However, the paper also addresses potential challenges in this transition, including impacts on food security and increased water consumption for cultivation of bio-mass. The research recommends strategic policy interventions, such as Pigouvian tax and subsidies, to facilitate a gradual shift, emphasizing the importance of balancing economic feasibility and environmental sustainability.