Production Of Olefins Research Articles

Catalytic pyrolysis of straight-run light oil to light olefins: Role of molecular structure and catalytic materials

The development of straight-run light oil catalytic pyrolysis to light olefins process is an important approach of achieving the transformation and upgrading of the current oil refining industry. However, the industrialization of the catalytic pyrolysis process for straight-run light oil has been slow. Herein, we investigated the decomposition of complex straight-run light oil into different structural units and further examined their effects on light olefins production. The results indicated that the yields of light olefins cracked over MFI zeolite were about 45 % and 30 % for alkane structure and cycloalkane ring structure, respectively. Further analysis showed that the olefin structure could theoretically be cracked to 100 % light olefins, but in fact, 40 % of the light olefins were lost due to the transfer of 10 % hydrogen. Subsequently, the effects of zeolite topology and acid properties on the cracking of different structural units were further analyzed. It was found that zeolites with MTT and MFI topologies contributed to the catalytic pyrolysis of chain and cycloalkane ring structures, respectively, because appropriate pore size helped diffusion of hydrocarbon molecules and inhibited side reactions such as hydrogen transfer. Compared with MFI zeolite, the light olefins yield produced by chain structure cracking over MTT zeolite increased by 5.83 %-10.54 %. In addition, it was discovered that zeolites with total and strong acids in the range of 0.2–0.4 mmol/g and 0.1–0.2 mmol/g, respectively, were beneficial for the cracking of light alkanes in straight-run light oils to light olefins. This work provides useful insights into the fundamental understanding and development of straight-run light oil catalytic pyrolysis to light olefins process.

Switchable production of aromatics and alkanes by Ni-ReOx/CeO2-catalyzed wood depolymerization

Complete conversion of lignocellulosic biomass into chemicals and fuels is particularly attractive in biorefinery concept while remains a great challenge due to complicated structure of lignocellulose and its notorious resistance to chemical transformation. Herein, a recyclable multifunctional Ni-ReOx/CeO2 catalyst was designed for switchable conversion of lignocellulose to either aromatics or liquid fuels by simple tuning reaction parameters. Under the condition of 200 °C, 1 MPa H2, lignin in woody biomass was deconstructed via lignin-first manner to produce aromatic oil with the mass yield up to 88.4 %, leaving cellulose and hemicellulose intact. Under harsher condition (260 °C, 4 MPa H2), complete conversion of lignocellulose to alkanes was achieved in 43.8 % carbon yield. The control experiments and characterization of the catalyst revealed that ReOx species of Ni-ReOx/CeO2 enhanced Ni dispersion, the strong electronic interaction and synergic effects of Ni and ReOx species played major roles for the flexible transformation.

"Alkene-to-Alkene" Difunctionalization of Enaminones for the Synthesis of Polyfunctionalized Alkenes by Transition-Metal-Free C-H and C-N Bond Transformation.

The three-component reactions of enaminones, disulfides, and alcohols for the synthesis of polyfunctionalized alkenes have been realized via the C-H and C-N bond transformation on enaminones. The reactions proceed in a novel "alkene-to-alkene" difunctionalization mode without using any transition metal. The application of the alkene products in the synthesis of divergent sulfenyl heteroaryls, including sulfenylated pyrazoles, pyrimidines, and isoxazoles, via simple annulation has also been verified.

Modulating the Formation of Coke to Improve the Production of Light Olefins from CO2 Hydrogenation over In2O3 and SSZ-13 Catalysts

Modulating the Formation of Coke to Improve the Production of Light Olefins from CO₂ Hydrogenation over In₂O₃ and SSZ-13 Catalysts

Promoter Effect on Carbon Nanosphere-Encapsulated Fe-Co Catalysts for Converting CO2 to Light Olefins

For this work, we investigated the promotor effect (M = Na+, K+, Ce3+, Zn2+, Mn2+) on carbon nanosphere-encapsulated bimetallic Fe-Co core–shell catalysts for CO2 hydrogenation, promising selectivity for converting CO2 to light olefins. The fresh and spent catalysts were characterized using a combination of experimental techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis and differential scanning calorimetry (TGA–DSC), and Raman spectroscopy, and our results reveal that the addition of the promotor M enhanced the formation of graphitic carbon and metal carbides in the promoted catalysts when compared with the unpromoted catalysts. The metal carbides were determined to be the active sites for the production of light olefins.

Modeling and analysis of air combustion and steam regeneration in methanol to olefins processes

Light olefins is the incredibly important materials in chemical industry. Methanol to olefins (MTO), which provides a non-oil route for light olefins production, received considerable attention in the past decades. However, the catalyst deactivation is an inevitable feature in MTO processes, and regeneration, therefore, is one of the key steps in industrial MTO processes. Traditionally the MTO catalyst is regenerated by removing the deposited coke via air combustion, which unavoidably transforms coke into carbon dioxide and reduces the carbon utilization efficiency. Recent study shows that the coke species over MTO catalyst can be regenerated via steam, which can promote the light olefins yield as the deactivated coke species can be essentially transferred to industrially useful synthesis gas, is a promising pathway for further MTO processes development. In this work, we modelled and analyzed these two MTO regeneration methods in terms of carbon utilization efficiency and technology economics. As shown, the steam regeneration could achieve a carbon utilization efficiency of 84.31%, compared to 74.74% for air combustion regeneration. The MTO processes using steam regeneration can essentially achieve the near-zero carbon emission. In addition, light olefins production of the MTO processes using steam regeneration is 12.81% higher than that using air combustion regeneration. In this regard, steam regeneration could be considered as a potential yet promising regeneration method for further MTO processes, showing not only great environmental benefits but also competitive economic performance.

Modulated oxygen mobility of perovskite oxides for efficient redox oxidative cracking of cycloalkane to light olefins

Oxidative cracking is a promising process to reduce the energy and carbon intensities for light olefins production by combing catalytic oxidation and cracking reactions. This work reports an efficient redox oxidative cracking (ROC), which could avoid the potential hazard of co-feed oxygen with hydrocarbons and save the air separation process in an oxidative cracking process to achieve a much safer reaction process and more energy saving. Highly efficient redox catalysts, i.e. composites of the Li2CO3 promoted perovskite oxides (La0.8Sr0.2FeO3 and CaMnO3), were applied in ROC of naphtha by using a model compound of cyclohexane. Among the catalysts, La0.8Sr0.2FeO3@Li2CO3 exhibits excellent ROC performance (57.52 % yield of olefins and extremely low COx yield of 0.28 %), and it demonstrates high structural stability and cycling ability as well. The olefins yield in this work increased by > 19 % compared to conventional non-oxidative catalytic cracking (38 % yield of olefins), and the COx yield also decreased from 18 % to extremely low of 0.28 % compared with the best-reported O2-cofeed cyclohexane oxidative cracking. The characterization results indicated that La0.8Sr0.2FeO3@Li2CO3 attributed to being a core–shell structure with a La0.8Sr0.2FeO3 core covering with a molten Li2CO3 layer. Further characterization indicates that the modification of Li2CO3 affected the migration rate of oxygen and inhibited the excessive oxidation of olefins, which enhancing the selectivity of light olefins and inhibits COx formation. The oxygen migration rate of LSF is 5.81 × 10−11 mol/(g·s) compared with 3.37 × 10−11 mol/(g·s) of LSF@20 %Li. These findings offer a new strategy to design effective redox catalysts for redox oxidative cracking.

Simultaneous catalytic dehydration of methanol and ethanol: How ZSM-5 acidity addresses conversion and products distribution

The sustainable chemistry based on acid-catalysed alcohol conversion reaction is a promising route to contribute to the de-fossilization strategies completion. In this concern, C1 and C2 alcohols are both well recognised sources for the production of ethers and olefins from sustainable sources in acid catalysed dehydration reaction pathway. Most of the literature is devoted to the investigation of pure alcohols conversion, whilst the simultaneous dehydration of alcohol in mixture can broad the product panel (contributing to the enlargement of bio-alcohols based chemistry) also elucidating the role of acidity (type and distribution) on the reaction mechanism. This paper is the first contribution analysing the role of acid sites (amount and distribution) on the simultaneous methanol/ethanol dehydration using ZSM-5 zeolites. ZSM-5 materials with different aluminium content were synthesised and used in catalytic test. The obtained results showed how Lewis acid sites are less important when dealing with ethanol (also in mixture with methanol) and how the different methylated- ethylated species formation can affect the product composition and the coke amount and composition.

Electroreductive Deoxygenative C−H and C−C Bond Formation from Non‐Derivatized Alcohols Fueled by Anodic Borohydride Oxidation

AbstractAlcohols are one of the most common organic compound classes among natural and synthetic products. Thus, methods for direct removal of C−OH groups without the need for wasteful pre‐functionalization are of great synthetic interest to unlock the full synthetic potential of the compound class. Herein, electroreductive C−OH bond activation and subsequent deoxygenative C−H and C−C bond formation of benzylic and propargylic alcohols are demonstrated along with mechanistic insights. Experimental and theoretical studies indicate that the reductive C−OH bond cleavage furnishes an open shell intermediate that undergoes a radical‐polar crossover to the corresponding carbanion that subsequently undergoes protonation to furnish alkane products. Furthermore, we demonstrate that the carbanion can be trapped with CO2 to form arylacetic acids. The cathodic transformations are efficiently balanced by the anodic oxidation of sub‐stoichiometric borohydride additives, a strategy that serves as a highly attractive alternative to the use of sacrificial metal anodes.

Relay Catalysis for Highly Selective Conversion of Methanol to Ethylene in Syngas.

The precise C-C coupling is a challenging goal in C1 chemistry. The conversion of methanol, a cheap and easily available C1 feedstock, into value-added and largely demanded olefins has been playing a game-changing role in the production of olefins. The current methanol-to-olefin (MTO) process, however, suffers from limited selectivity to a specific olefin. Here, we present a relay-catalysis route for the high-selective conversion of methanol to ethylene in syngas (H2/CO) typically used for methanol synthesis. A bifunctional catalyst composed of selectively dealuminated H-MOR zeolite and ZnO-TiO2, which implemented methanol carbonylation with CO to acetic acid and selective acetic acid hydrogenation to ethylene in tandem, offered ethylene selectivity of 85% at complete methanol conversion at 583 K. The selective removal of Brønsted acid sites in the 12-membered ring channel of H-MOR favors the selectivity of acetic acid in CH3OH carbonylation. The high capabilities of ZnO-TiO2 in the adsorption of acetic acid and the activation of H2 play key roles in selective hydrogenation of acetic acid to ethylene. Our work provides a promising relay-catalysis strategy for precise C-C coupling of C1 to C2 molecules.

Fischer–Tropsch synthesis over the Co–Ni/Al2O3 nanocatalyst: influence of process variables, modeling and optimization using response surface methodology

AbstractBACKGROUNDLight olefins production greatly influenced by the process conditions. In the present work Al2O3 supported Co‐Ni nanocatalysts were evaluated for production of light olefins. Incipient wetness impregnation procedure was used for catalyst synthesis. Catalysts were characterized for determining the physicochemical properties using various techniques of XRD, SEM, EDS, H2‐TPR, TPD, TEM, XPS, TGA, DSC, FT‐IR, and BET. The influence of process conditions (Pressure, Temperature and H2/CO inlet feed molar ratio) was investigated on the catalytic performance of Co‐Ni/γAl2O3 nanocatalyst toward lower olefins. Temperature, pressure, and feed ratio factors were changed in wide ranges of 250–450 °C, 1–12 bar, and 1–4 respectively. The Response Surface Methodology (RSM) method was employed for modeling and optimization.RESULTSThe optimum process conditions were obtained using the RSM method (T = 383 °C, P = 4 bar, and H2/CO = 1.92). The highest selectivity of light olefinic products and conversion of carbon monoxide and the lowest selectivity toward methane were obtained concurrently under the optimized conditions with desirability of 0.896.CONCLUSIONThe impact of inlet feed ratio, temperature, and pressure factors was investigated and it was found that the performance of the catalyst greatly depends on the operational parameters. © 2023 Society of Chemical Industry.

Advances in Oxidative Coupling of Methane

C2+ hydrocarbons, especially C2+ olefins, as important basic chemical raw materials, mainly come from petroleum cracking. With the increasing scarcity of petroleum resources, the search for new olefins production routes has become the focus of research, and the production of olefins by the oxidative coupling of methane (OCM) process has attracted extensive attention. The OCM route is an important alternative to the production of olefins from petroleum resources and is also an important direction for the development of efficient and clean utilization of natural gas. In this paper, the mechanism, catalysts, and other key factors for the production of olefins by methane oxidative coupling are reviewed. The mechanism of OCM, including the reaction pathway and the formation of intermediate products, is introduced. Then, commonly used catalysts, such as alkali metal/alkaline earth metal oxides, rare earth metal oxides, composite metal oxides with special structures, and classical catalysts Mn/Na2WO4/SiO2, and their mechanisms of action in the reaction are discussed. In addition, the application of chemical looping oxidative coupling of methane (CLOCM) in olefin production is also investigated, which is a promising alternative way due to the high selectivity of olefins and the low cost of catalysts owing to the excellent performance of the catalyst recycling. These studies will help to further understand the mechanism of OCM for olefin production and provide guidance and support for applications in related fields.

Phosphinite‐Ligand‐Assisted Chromium Pre‐catalysts and their Ethylene Oligomerization Properties

AbstractPhosphinite based ligands with or without a secondary nitrogen binding site have been evaluated for the first time towards chromium catalyzed ethylene oligomerization using modified aluminoxane (MMAO‐12) as an activator. Through systematic optimization of the reaction parameters specifically the reaction temperature, olefin selectivity up to 92 wt % could be achieved. In particular, at higher temperature (~75 °C), the rate of β‐hydrogen elimination leading to the formation of olefinic products, is relatively more favorable over the rate of propagation which produces polyethylene. Overall, the present study reveals that the phosphinite type ligands could promote ethylene oligomerization, although nonselective way to yield olefin products with carbon number ranging from C6−C14 while yielding highest productivity up to 12517 g/gCr.h.

Electrification of steam cracking as a pathway to reduce the impact of the petrochemical industry on climate change

In the Chemical Process Industry (CPI) only hydrogen production from steam methane reforming produces more greenhouse gas emissions than light olefins production. Various solutions have been proposed to reduce the CO2 emissions from olefins production. It is not clear which solution is best, particularly when you consider other sustainability factors. In this paper we report the results of our cradle-to-gate life cycle assessment (LCA) of three highly promising solutions: a so-called low-emission steam cracking furnace, the electrically driven RotoDynamic reactor (RDR), and a blue hydrogen-fired furnace. Life cycle inventory data is obtained from a first principles model for steam cracking, validated with industrial data, and combined with data obtained from process simulation. Our study shows that if the electrical supply is grey then the RDR-based cracking process has a 41% higher impact on climate change than the reference base case, a conventional plant with state-of-the-art furnaces. The low-emission furnace is only 7.2% higher. When using a mixed electrical grid, like Belgium's, the climate change impact for the RDR is 1.5% higher and the low emission furnace is 6.6% lower. With a grid that uses fully renewable power generation the RDR solution is an impressive 27% lower than the base case and the low-emission furnace 17% lower. We also analysed the impact of firing the furnaces with blue hydrogen from (a) a conventional steam-methane reformer and (b) an innovative gas-heated reformer: both (a) and (b) using carbon capture and storage (CCS). The climate change impact is reduced by 8% and 18% respectively compared to the base case. Since the blue hydrogen solution uses very little electricity, the climate change impact is insensitive to the method of electrical power generation.

The Potential of Platanus orientalis L. Bark for High-Grade Resource Utilization

Forest wood biomass can be used as a renewable resource for the sustainable production of fuels and chemicals. In this study, the methanol, methanol/ethanol, and ethanol/benzene solvent extracts of Platanus orientalis L. bark were analyzed using FTIR, IH NMR, 13C NMR, 2D-HSQC NMR, GC-MS, and TOF-LC-MS. The results revealed that the bark of Planus orientalis contained a wide variety of chemical compounds, such as 30-triacontanol, 1-Hexanol, hexadecanoic acid, methyl ester, 2-ethyl-, γ-Sitosterol, and 3,4,5-tri methoxy-Phenol. In addition, the fast pyrolysis of P. orientalis L. bark (POL-B) with nano-catalysts (Co3O4, Fe2O3, and Co3O4/Fe2O3) was investigated using pyrolysis/gas chromatography/mass spectrometry (Py-GC/MS) and a thermogravimetric analyzer coupled with an FTIR spectrophotometer (TG-FTIR). The TG results revealed that the nano-catalysts significantly affected the pyrolysis of P. orientalis bark. The nano-Fe2O3 catalyst was shown to increase acid and ketone compound production during the catalytic pyrolysis of cellulose. According to the Py-GC-MS results, the pyrolytic products contained several value-added chemicals and high-quality bio-oil. The nano-catalysts promoted the production of aromatics, phenols, ketones, olefins, furans and alkane compounds. These natural-product active molecules and bio-oil, as high-grade raw materials, could be used in many industrial and agricultural fields for the production of wetting agents, stabilizers, plasticizers and resins. In addition, a number of active molecules could be used as drugs and biomedical active ingredients for anti-cancer and anti-inflammatory purposes.

Experimental study on the mechanism of water on heat sink variation in catalytic partial steam reforming of supercritical n-decane

Regenerative cooling is an effective method for heat management of hypersonic vehicles and faces a problem of insufficient cooling capacity under higher flight Mach number. Water-assisted hydrocarbon fuels thermal conversion can effectively increase heat absorption and inhibit carbon deposition. The mechanism of water on the variation of heat sink is unclear. In this study, experimental study was conducted to investigate the effect of different water contents, pressure and mass flow rates on the variation of heat sink and the distribution of gaseous products in a continuous experimental system. The results show that catalytic partial steam reforming reaction consists of catalytic steam reforming and catalytic thermal cracking in the low temperature stage (T＜490 ℃), and non-catalytic thermal cracking is activated and gradually dominate in the high temperature stage (T＞490 ℃). The contribution of water to total heat sink is mainly caused by physical heat sink. Increasing mass flow rate mainly suppress the cracking reaction in the high temperature section by reducing reaction residence time. The flow rate has little effect on the chemical reaction equilibrium. Higher pressure has little effect on heat sink, but accelerates carbon deposition by promoting the formation of olefin products.

On the transition to gasoline-to-olefins chemistry in the cracking reactions of 1-octene over H-ZSM-5 catalysts

The cracking reactions of 1-octene over H-ZSM-5 zeolite are studied via micro-reactor and off-line spectroscopic techniques for up to 72 h on stream and a temperature range of 473–673 K. 1-Octene is found to react via a two-cycle hydrocarbon pool mechanism, with strong similarities to that reported for methanol-to-hydrocarbons chemistry. This dual-cycle mechanism requires temperatures of 673 K or higher to function with full efficiency, with lower temperatures deactivating portions of the cyclic mechanism, leading to premature deactivation of the catalyst through over-production of coke species. Inelastic neutron scattering is used to study the coke composition, identifying two distinct deactivation mechanisms depending on reaction temperature. The catalyst is also found to slowly progress from an aromatic-heavy to an olefin-heavy product regime even at full efficiency due to progressive blockage of active sites by amorphous carbon-rich coke. Artificial aging of the zeolite, through steam treatment, is found to shift the catalyst lifetime so that it commences at a later stage in this process, resulting in increased light olefin production. The reduced aromatic production also means that deactivation of the catalyst occurs more slowly in steamed catalysts than in fresh ones, after an equivalent time-on-stream. Collectively, these observations connect with the application of ZSM-5 catalysts to facilitate gasoline-to-olefins chemistry in fluidised catalytic cracking unit operations.

Multi-objective optimization strategy for industrial catalytic cracking units: Kinetic model and enhanced SPEA-2 algorithm with economic, CO2, and SO2 emission considerations

The multi-objective optimization of the economics and environmental protection of the fluidized catalytic cracking reaction-regeneration (FCC-RR) process can achieve a balanced production of light olefins, and other chemicals while mitigating pollutant gas emissions. This paper proposes a novel multi-objective optimization framework that integrates the FCC-RR lumped kinetic model and SPEA-2 algorithm based on the path evolution reproduction operator. The proposed FCC-RR model not only provides insights into the influence of various reaction variables on product yields from a mechanistic perspective but also accurately simulates the distribution of products during the reaction-regeneration process. Additionally, we present an improved SPEA-2 algorithm that incorporates the path evolution operator and applies it to a real FCC-RR device to speed up the optimization process in terms of solution speed and quality. The results of the case study demonstrate that the proposed optimization framework has significant advantages in solving multi-objective optimization in the catalytic cracking process.

Nickel-Catalyzed Reductive Cross-Coupling of Allylammonium Salts with Alkyl Iodides.

An unprecedented reductive cross-coupling reaction of allylammonium salts with alkyl electrophiles has been established through C-N bond cleavage. A range of allylammonium bromides smoothly participated in the nickel-catalyzed zinc-mediated allyl-alkyl cross-electrophile coupling reaction with alkyl iodides, delivering structurally diverse alkene products in moderate to good yields with high linear selectivity. Preliminary mechanistic experiments are consistent with the formation of an alkyl radical from the alkyl iodide.

Insight into the synergistic effect of copper and sodium over metal organic framework-derived Fe-based catalyst for CO2 hydrogenation to aromatics

One-step hydrogenation of carbon dioxide (CO2) to aromatics is a promising strategy for relieving the stress of fossil fuels. Here, a copper and sodium co-modified Fe-based catalyst (3-NFC-5) was synthesized through the pyrolysis of Cu-doped MIL-101(Fe) and Na impregnation. After combining with HZSM-5, 42.11% CO2 conversion and 50.68% total aromatics selectivity was achieved. Through multiple characterization and DFT calculations, the synergistic promotion of Na and Cu on light olefins intermediate production was revealed. Na was crucial for COOH* formation as the intermediate for reverse water gas shift reaction (RWGS), whose concentration could be further enhanced after Cu modification. Controlled C-C coupling towards C2-C4 hydrocarbons was realized by the enhanced CO non-dissociative activation and the increased content of χ-Fe5C2 after Cu doping, which was responsible for the inhibited surface CHx* concentration and selective production of light olefins, respectively.