Articles de revues : « Light Olefines »

1

Du, Lingyin, Yueyang Han et Youhao Xu. « Effect of Molecular Structure of C10 Hydrocarbons on Production of Light Olefins in Catalytic Cracking ». Catalysts 13, n^o 6 (16 juin 2023) : 1013. http://dx.doi.org/10.3390/catal13061013.

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The effect of the molecular structure of feedstock on the cracking reaction of C10 hydrocarbons to ethylene and propylene over H-ZSM-5 zeolite was investigated. To better compare the effect of decane on the production of light olefins, the thermal cracking and catalytic cracking performance of decane were first investigated. As a comparison, the thermal cracking and catalytic cracking of decane were studied by cracking over quartz sand and H-ZSM-5. Compared with the thermal cracking reaction over quartz sand, the catalytic cracking reaction of decane over H-ZSM-5 has a significantly higher conversion and light olefins selectivity, especially when the reaction temperature was lower than 600 °C. On this basis, the catalytic cracking reactions of decane and decene over H-ZSM-5 were further compared. It was found that decene with a double bond structure had high reactivity over H-ZSM-5 and was almost completely converted, and the product was mainly olefin. Compared with decane as feedstock, it has a lower methane yield and higher selectivity of light olefins. Therefore, decene was more suitable for the production of light olefins than decane. To this end, we designed a new light olefin production process. Through olefin cracking, the yield of light olefins in the product can be effectively improved, and the proportion of different light olefins such as ethylene, propylene and butene can be flexibly adjusted.

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Vosmerikov, Anton A., Ludmila N. Vosmerikova et Alexander V. Vosmerikov. « STUDYING THE INFLUENCE OF ALKALINE TREATMENT AND MODIFICATION OF ZEOLITE ON ITS PHYSICAL-CHEMICAL AND CATALYTIC PROPERTIES IN THE PROCESS OF PROPANE CONVERSION TO OLEFIN HYDROCARBONS ». ChemChemTech 67, n^o 8 (23 juillet 2024) : 50–58. http://dx.doi.org/10.6060/ivkkt.20246708.11t.

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In this work, the effect of alkaline treatment of ZSM-5 zeolite with a modulus of 100 on its physicochemical properties and activity in the process of converting propane into olefin hydrocarbons was investigated. The growing demand for lower olefins is driving the search for new ways to improve existing technologies and develop new, more efficient catalysts. Catalytic dehydrogenation of light alkanes is an alternative to the petrochemical method for producing lower olefins from cheap and available gas and oil and gas feedstocks. At the same time, dehydrogenation reactions of light alkanes have a number of features and limitations that determine the range of possible catalysts. Zeolites are a class of supports that, due to their large surface area, nanometer-sized pores, and good thermal stability, can be used to prepare catalysts for the dehydrogenation of C2−C4 alkanes. An important feature of crystalline high-silica zeolites is the ability to change their acidic properties under the influence of various pre-treatments, which opens up great opportunities for their regulation and, accordingly, the selection of the most effective catalyst for a particular chemical process. It has been shown that alkaline treatment of zeolite leads to the formation of an additional amount of mesopores, which, in turn, affects its catalytic properties in the process of converting propane into olefinic hydrocarbons. The dependence of the activity and selectivity of the zeolite catalyst on the concentration of the alkali solution used for its treatment has been established. It was found that treatment of the zeolite catalyst with a 1.0 M NaOH solution leads to an increase in its selectivity with respect to the formation of C2–C4 olefins from propane, which at a process temperature of 650 °C reaches 32.0% with a propane conversion of 81%. It has been shown that additional promotion of desilicated zeolite with magnesium or manganese increases its activity with respect to the formation of olefinic hydrocarbons from propane. For citation: Vosmerikov A.A., Vosmerikova L.N., Vosmerikov A.V. Studying the influence of alkaline treatment and modification of zeolite on its physical-chemical and catalytic properties in the process of propane conversion to olefin hydrocarbons. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 8. P. 50-58. DOI: 10.6060/ivkkt.20246708.11t.

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Pawelec, Barbara, Rut Guil-López, Noelia Mota, Jose Fierro et Rufino Navarro Yerga. « Catalysts for the Conversion of CO2 to Low Molecular Weight Olefins—A Review ». Materials 14, n^o 22 (17 novembre 2021) : 6952. http://dx.doi.org/10.3390/ma14226952.

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There is a large worldwide demand for light olefins (C2=–C4=), which are needed for the production of high value-added chemicals and plastics. Light olefins can be produced by petroleum processing, direct/indirect conversion of synthesis gas (CO + H2) and hydrogenation of CO2. Among these methods, catalytic hydrogenation of CO2 is the most recently studied because it could contribute to alleviating CO2 emissions into the atmosphere. However, due to thermodynamic reasons, the design of catalysts for the selective production of light olefins from CO2 presents different challenges. In this regard, the recent progress in the synthesis of nanomaterials with well-controlled morphologies and active phase dispersion has opened new perspectives for the production of light olefins. In this review, recent advances in catalyst design are presented, with emphasis on catalysts operating through the modified Fischer–Tropsch pathway. The advantages and disadvantages of olefin production from CO2 via CO or methanol-mediated reaction routes were analyzed, as well as the prospects for the design of a single catalyst for direct olefin production. Conclusions were drawn on the prospect of a new catalyst design for the production of light olefins from CO2.

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Natarajan, Palani, Deachen Chuskit et Priya. « Readily available alkylbenzenes as precursors for the one-pot preparation of buta-1,3-dienes under DDQ visible-light photocatalysis in benzotrifluoride ». Organic Chemistry Frontiers 9, n^o 5 (2022) : 1395–402. http://dx.doi.org/10.1039/d1qo01869h.

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By using DDQ visible-light photocatalysis, an olefin-free method for the production of buta-1,3-dienes is disclosed. DDQ* converts alkylbenzenes to olefins and then olefins to buta-1,3-dienes in a consecutive manner.

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Liu, Fei, Ting Li, Peng Long Ye, Xiao Dan Wang, Jian Xin Cao et Duan Hua Guo. « Effect of Fe Loading Content on Catalytic Performance of ZSM-5 for the IMTO Process ». Advanced Materials Research 648 (janvier 2013) : 135–38. http://dx.doi.org/10.4028/www.scientific.net/amr.648.135.

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Among the processes for production of olefins, methanol converted to light olefins with methyl iodide as intermediate is a potential and an alternative route, which can be realized under mild condition. ZSM-5 catalyst is considered to be an effective catalyst for methanol to light olefins, better performances for olefins can be obtained by modifying. In this paper, the methanol to olefin with iodide reaction (IMTO) has been studied in a small scale fixed bed reactor over Fe modified ZSM-5 catalyst. It is indicated that ZSM-5 zeolites were modified with Fe loadings successfully, as a result the pore sizes reduced availably comparing with ZSM-5, the conversion of methanol and selectivity of light olefins got 98.8% and 89.5% respectively when modified with 9% Fe loadings.

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Kang, Jong Hun. « Development of shape selectivity theory of methanol-to-olefins reaction over small-pore zeolite molecular sieves ». Ceramist 25, n^o 2 (30 juin 2022) : 145–58. http://dx.doi.org/10.31613/ceramist.2022.25.2.01.

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The methanol-to-olefins reaction is regarded as an important technology capable of meeting today’s rising demand for light olefins. The regioselective confinement effect of small-pore, cage-type zeolites on hydrocarbon pool intermediates results in strong shape selectivity determining the product olefin distribution. Despite decades of effort, a direct correlation between zeolite cage topologies and olefin selectivity distributions had remained elusive. The cage-defining ring theory is the first general catalytic shape selectivity theory that can predict the selectivity distribution of product light olefins from the given crystallographic information of the small pore zeolite catalysts. This article outlines the development procedure of the cagedefining ring theory. To aid readers’ comprehension, brief introductions to the structures and properties of zeolites and related molecular sieves, which are an important class of ceramic catalysts, are also provided.

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Yahyazadeh, Arash, Ajay K. Dalai, Wenping Ma et Lifeng Zhang. « Fischer–Tropsch Synthesis for Light Olefins from Syngas : A Review of Catalyst Development ». Reactions 2, n^o 3 (21 juillet 2021) : 227–57. http://dx.doi.org/10.3390/reactions2030015.

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Light olefins as one the most important building blocks in chemical industry can be produced via Fischer–Tropsch synthesis (FTS) from syngas. FT synthesis conducted at high temperature would lead to light paraffins, carbon dioxide, methane, and C5+ longer chain hydrocarbons. The present work focuses on providing a critical review on the light olefin production using Fischer–Tropsch synthesis. The effects of metals, promoters and supports as the most influential parameters on the catalytic performance of catalysts are discussed meticulously. Fe and Co as the main active metals in FT catalysts are investigated in terms of pore size, crystal size, and crystal phase for obtaining desirable light olefin selectivity. Larger pore size of Fe-based catalysts is suggested to increase olefin selectivity via suppressing 1-olefin readsorption and secondary reactions. Iron carbide as the most probable phase of Fe-based catalysts is proposed for light olefin generation via FTS. Smaller crystal size of Co active metal leads to higher olefin selectivity. Hexagonal close-packed (HCP) structure of Co has higher FTS activity than face-centered cubic (FCC) structure. Transition from Co to Co3C is mainly proposed for formation of light olefins over Co-based catalysts. Moreover, various catalysts’ deactivation routes are reviewed. Additionally, techno-economic assessment of FTS plants in terms of different costs including capital expenditure and minimum fuel selling price are presented based on the most recent literature. Finally, the potential for global environmental impacts associated with FTS plants including atmospheric and toxicological impacts is considered via lifecycle assessment (LCA).

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Gholami, Zahra, Fatemeh Gholami, Zdeněk Tišler, Martin Tomas et Mohammadtaghi Vakili. « A Review on Production of Light Olefins via Fluid Catalytic Cracking ». Energies 14, n^o 4 (19 février 2021) : 1089. http://dx.doi.org/10.3390/en14041089.

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The fluid catalytic cracking (FCC) process is an alternative olefin production technology, with lower CO2 emission and higher energy-saving. This process is used for olefin production by almost 60% of the global feedstocks. Different parameters including the operating conditions, feedstock properties, and type of catalyst can strongly affect the catalytic activity and product distribution. FCC catalysts contain zeolite as an active component, and a matrix, a binder, and a filler to provide the physical strength of the catalyst. Along with the catalyst properties, the FCC unit’s performance also depends on the operating conditions, including the feed composition, hydrocarbon partial pressure, temperature, residence time, and the catalyst-to-oil ratio (CTO). This paper provides a summary of the light olefins production via the FCC process and reviews the influences of the catalyst composition and operating conditions on the yield of light olefins.

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Salah Aldeen, Omer Dhia Aldeen, Mustafa Z. Mahmoud, Hasan Sh Majdi, Dhameer A. Mutlak, Khusniddin Fakhriddinovich Uktamov et Ehsan kianfar. « Investigation of Effective Parameters Ce and Zr in the Synthesis of H-ZSM-5 and SAPO-34 on the Production of Light Olefins from Naphtha ». Advances in Materials Science and Engineering 2022 (24 février 2022) : 1–22. http://dx.doi.org/10.1155/2022/6165180.

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In this paper, Ce and Zr modified commercial SAPO-34 and H-ZSM-5 catalysts were synthesized via a wet impregnation method and used as catalysts for the production of light olefins from naphtha. The synthesized catalysts were characterized using SEM, TGA, XRD, BET, and NH3-TPD. Thermal catalytic cracking of parent catalysts (SAPO-34 and H-ZSM-5) and modified catalysts with Ce and Zr on the production of light olefins from naphtha has been studied. The effects of different loading of Ce (2–8 wt.%), Zr (2–5 wt.%), and different temperatures on the yield of ethylene and propylene were also investigated. The yield of ethylene and propylene improved by 21.78 wt% and 23.8 wt%, respectively, over 2% Ce and 2% Zr on SAPO-34 catalyst. This is due to the higher acid sites on the surface of modified catalysts. It was found that H-ZSM-5 with 2% Zr loading has the highest yield of light olefins (40.4%) at 650°C in comparison with unmodified parent catalysts, while Ce loading has less effect on the olefin yield compared to Zr loading. Finally, simultaneous loading of Ce and Zr showed no effect on the light olefin yield owing to the significant decline of acid sites.

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Gholami, Zahra, Fatemeh Gholami, Zdeněk Tišler, Jan Hubáček, Martin Tomas, Miroslav Bačiak et Mohammadtaghi Vakili. « Production of Light Olefins via Fischer-Tropsch Process Using Iron-Based Catalysts : A Review ». Catalysts 12, n^o 2 (28 janvier 2022) : 174. http://dx.doi.org/10.3390/catal12020174.

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The production of light olefins, as the critical components in chemical industries, is possible via different technologies. The Fischer–Tropsch to olefin (FTO) process aims to convert syngas to light olefins with high selectivity over a proper catalyst, reduce methane formation, and avoid the production of excess CO2. This review describes the production of light olefins through the FTO process using both unsupported and supported iron-based catalysts. The catalytic properties and performances of both the promoted and bimetallic unsupported catalysts are reviewed. The effect of support and its physico-chemical properties on the catalyst activity are also described. The proper catalyst should have high stability to provide long-term performance without reducing the activity and selectivity towards the desired product. The good dispersion of active metals on the surface, proper porosity, optimized metal-support interaction, a high degree of reducibility, and providing a sufficient active phase for the reaction are important parameters affecting the reaction. The selection of the suitable catalyst with enhanced activity and the optimum process conditions can increase the possibility of the FTO reaction for light-olefins production. The production of light olefins via the FTO process over iron-based catalysts is a promising method, as iron is cheap, shows higher resistance to sulfur, and has a higher WGS activity which can be helpful for the feed gas with a low H2/CO ratio, and also has higher selectivity towards light olefins.

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Dugkhuntod, Pannida, et Chularat Wattanakit. « A Comprehensive Review of the Applications of Hierarchical Zeolite Nanosheets and Nanoparticle Assemblies in Light Olefin Production ». Catalysts 10, n^o 2 (18 février 2020) : 245. http://dx.doi.org/10.3390/catal10020245.

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Light olefins including ethylene, propylene and butylene are important building blocks in petrochemical industries to produce various chemicals such as polyethylene, polypropylene, ethylene oxide and cumene. Traditionally, light olefins are produced via a steam cracking process operated at an extremely high temperature. The catalytic conversion, in which zeolites have been widely used, is an alternative pathway using a lower temperature. However, conventional zeolites, composed of a pure microporous structure, restrict the diffusion of large molecules into the framework, resulting in coke formation and further side reactions. To overcome these problems, hierarchical zeolites composed of additional mesoporous and/or macroporous structures have been widely researched over the past decade. In this review, the recent development of hierarchical zeolite nanosheets and nanoparticle assemblies together with opening up their applications in various light olefin productions such as catalytic cracking, ethanol dehydration to ethylene, methanol to olefins (MTO) and other reactions will be presented.

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Emberru, Ruth Eniyepade, Raj Patel, Iqbal Mohammed Mujtaba et Yakubu Mandafiya John. « A Review of Catalyst Modification and Process Factors in the Production of Light Olefins from Direct Crude Oil Catalytic Cracking ». Sci 6, n^o 1 (4 février 2024) : 11. http://dx.doi.org/10.3390/sci6010011.

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Petrochemical feedstocks are experiencing a fast growth in demand, which will further expand their market in the coming years. This is due to an increase in the demand for petrochemical-based materials that are used in households, hospitals, transportation, electronics, and telecommunications. Consequently, petrochemical industries rely heavily on olefins, namely propylene, ethylene, and butene, as fundamental components for their manufacturing processes. Presently, there is a growing interest among refineries in prioritising their operations towards the production of fuels, specifically gasoline, diesel, and light olefins. The cost-effectiveness and availability of petrochemical primary feedstocks, such as propylene and butene, can be enhanced through the direct conversion of crude oil into light olefins using fluid catalytic cracking (FCC). To achieve this objective, the FCC technology, process optimisation, and catalyst modifications may need to be redesigned. It is helpful to know that there are several documented methods of modifying traditional FCC catalysts’ physicochemical characteristics to enhance their selectivity toward light olefins’ production, since the direct cracking of crude oil to olefins is still in its infancy. Based on a review of the existing zeolite catalysts, this work focuses on the factors that need to be optimized and the approaches to modifying FCC catalysts to maximize light olefin production from crude oil conversion via FCC. Several viewpoints have been combined as a result of this research, and recommendations have been made for future work in the areas of optimising the yield of light olefins by engineering the pore structure of zeolite catalysts, reducing deactivation by adding dopants, and conducting technoeconomic analyses of direct crude oil cracking to produce light olefins.

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Weber, Daniel, Tina He, Matthew Wong, Christian Moon, Axel Zhang, Nicole Foley, Nicholas J. Ramer et Cheng Zhang. « Recent Advances in the Mitigation of the Catalyst Deactivation of CO2 Hydrogenation to Light Olefins ». Catalysts 11, n^o 12 (28 novembre 2021) : 1447. http://dx.doi.org/10.3390/catal11121447.

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The catalytic conversion of CO2 to value-added chemicals and fuels has been long regarded as a promising approach to the mitigation of CO2 emissions if green hydrogen is used. Light olefins, particularly ethylene and propylene, as building blocks for polymers and plastics, are currently produced primarily from CO2-generating fossil resources. The identification of highly efficient catalysts with selective pathways for light olefin production from CO2 is a high-reward goal, but it has serious technical challenges, such as low selectivity and catalyst deactivation. In this review, we first provide a brief summary of the two dominant reaction pathways (CO2-Fischer-Tropsch and MeOH-mediated pathways), mechanistic insights, and catalytic materials for CO2 hydrogenation to light olefins. Then, we list the main deactivation mechanisms caused by carbon deposition, water formation, phase transformation and metal sintering/agglomeration. Finally, we detail the recent progress on catalyst development for enhanced olefin yields and catalyst stability by the following catalyst functionalities: (1) the promoter effect, (2) the support effect, (3) the bifunctional composite catalyst effect, and (4) the structure effect. The main focus of this review is to provide a useful resource for researchers to correlate catalyst deactivation and the recent research effort on catalyst development for enhanced olefin yields and catalyst stability.

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Abbas, Hadj Abbas, Zahra Asgar Pour, Mohammed S. Alnafisah, Pablo Gonzalez Cortes, Mustapha El Hariri El Nokab, Ahmed Elshewy et Khaled O. Sebakhy. « Enhanced Catalytic Hydrogenation of Olefins in Sulfur-Rich Naphtha Using Molybdenum Carbide Supported on γ-Al2O3 Spheres under Steam Conditions : Simulating the Hot Separator Stream Process ». Materials 17, n^o 10 (11 mai 2024) : 2278. http://dx.doi.org/10.3390/ma17102278.

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Spheres comprising 10 wt.% Mo2C/γ-Al2O3, synthesized through the sucrose route, exhibited unprecedented catalytic activity for olefin hydrogenation within an industrial naphtha feedstock that contained 23 wt.% olefins, as determined by supercritical fluid chromatography (SFC). The catalyst demonstrated resilience to sulfur, exhibiting no discernible deactivation signs over a tested 96 h operational period. The resultant hydrogenated naphtha from the catalytic process contained only 2.5 wt.% olefins when the reaction was conducted at 280 °C and 3.44 × 106 Pa H2, subsequently blended with Athabasca bitumen to meet pipeline specifications for oil transportation. Additionally, the carbide catalyst spheres effectively hydrogenated olefins under steam conditions without experiencing any notable hydrogenation in the aromatics. We propose the supported carbide catalyst as a viable alternative to noble metals, serving as a selective agent for olefin elimination from light petroleum distillates in the presence of steam and sulfur, mitigating the formation of gums and deposits during the transportation of diluted bitumen (dilbit) through pipelines.

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Shahul Hamid, Muhamed Yusuf, et Muhammad Hafizuddin Mohd Sofi. « Recent modifications of MCM-22 and MOR zeolite in MTO reaction : A review ». E3S Web of Conferences 516 (2024) : 02009. http://dx.doi.org/10.1051/e3sconf/202451602009.

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Since the discovery of the Methanol-to-Olefins (MTO) process as a sustainable and nonpetroleum method for generating light olefins, there has been a growing interest in the utilization of acidic zeolite catalysts. In this review, we highlighted the application and modification of MCM-22 and MOR zeolite catalysts, shedding light on their distinctive properties and the ongoing endeavors to optimize their catalytic performance. Notably, the choice of catalyst and specific modifications significantly influence the outcomes of light olefin selectivity, propylene-to-ethylene (P/E) ratios, and catalytic lifetime. This research offers insights into the current status of research on MCM-22 and MOR zeolites and imparts a valuable understanding of the developments of both catalysts in this crucial catalytic field.

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Lee, Joongwon, Seungwon Park, Ung Gi Hong, Jin Oh Jun et In Kyu Song. « Production of Light Olefins Through Catalytic Cracking of C5 Raffinate Over Surface-Modified ZSM-5 Catalyst ». Journal of Nanoscience and Nanotechnology 15, n^o 10 (1 octobre 2015) : 8311–17. http://dx.doi.org/10.1166/jnn.2015.11242.

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Surface modification of phosphorous-containing porous ZSM-5 catalyst (P/C-ZSM5-Sil.(X)) was carried out by a chemical liquid deposition (CLD) method using tetraethyl orthosilicate (TEOS) as a silylation agent. Different amount of TEOS (X = 5, 10, 20, and 30 wt%) was introduced into P/C-ZSM5il.(X) catalysts for surface modification. The catalysts were used for the production of light olefins (ethylene and propylene) through catalytic cracking of C5 raffinate. It was found that external surface acidity of P/C-ZSM5-Sil.(X) catalysts significantly decreased with increasing TEOS content. In the catalytic reaction, both conversion of C5 raffinate and yield for light olefins showed volcano-shaped curves with respect to TEOS content. Among the catalysts tested, P/C-ZSM5- Sil.(20) catalyst exhibited the best catalytic performance in terms of conversion of C5 raffinate and yield for light olefins. Thus, an optimal TEOS content was required for CLD treatment to maximize light olefin production in the catalytic cracking of C5 raffinate over P/C-ZSM5-Sil.(X) catalysts.

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Gholami, Zahra, Fatemeh Gholami, Zdeněk Tišler et Mohammadtaghi Vakili. « A Review on the Production of Light Olefins Using Steam Cracking of Hydrocarbons ». Energies 14, n^o 23 (6 décembre 2021) : 8190. http://dx.doi.org/10.3390/en14238190.

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Light olefins are the main building blocks used in the petrochemical and chemical industries for the production of different components such as polymers, synthetic fibers, rubbers, and plastic materials. Currently, steam cracking of hydrocarbons is the main technology for the production of light olefins. In steam cracking, the pyrolysis of feedstocks occurs in the cracking furnace, where hydrocarbon feed and steam are first mixed and preheated in the convection section and then enter the furnace radiation section to crack to the desired products. This paper summarizes olefin production via the steam cracking process; and the reaction mechanism and cracking furnace are also discussed. The effect of different operating parameters, including temperature, residence time, feedstock composition, and the steam-to-hydrocarbon ratio, are also reviewed.

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Bakhtiar, Syed ul Hasnain, Sher Ali, Xiaotong Wang, Fulong Yuan, Zhibin Li et Yujun Zhu. « Synthesis of sub-micrometric SAPO-34 by a morpholine assisted two-step hydrothermal route and its excellent MTO catalytic performance ». Dalton Transactions 48, n^o 8 (2019) : 2606–16. http://dx.doi.org/10.1039/c8dt04559c.

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SAPO-34 with a sub-micrometer crystal size was synthesized by a double hydrothermal treatment employing cost-effective morpholine as a structure directing agent, which presented an enhanced catalytic lifetime (nearly 3 times the conventional one) in the reaction of methanol to olefins with a higher light olefin selectivity (total selectivity of 97.1%).

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Wang, Min, Lucun Wang et Dong Ding. « Electrocatalytic Upgrading of CO₂ to Light Olefins in Protonic Ceramic Electrochemical Cells ». ECS Meeting Abstracts MA2024-01, n^o 37 (9 août 2024) : 2261. http://dx.doi.org/10.1149/ma2024-01372261mtgabs.

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Light olefins (ethylene, propylene, butylene) are primary building blocks for chemical manufacturing of large volume products including organic chemicals, plastics, and even sustainable aviation fuels. Currently, the dominant commercial process for olefin production is steam cracking of naphtha or ethane, which is highly energy intensive and accounts for a large fraction of global CO2 emissions. To decarbonize olefin production processes, electrochemical CO2-to-olefin conversion coupled with renewable or low-emission energy sources including electricity and heat offers an attractive alternative. Previously, extensive research efforts have been devoted to low temperature electrochemical CO2 reduction in aqueous media, i.e., occurring below 100 °C. This approach, however, still faces enormous scientific and technological challenges in improving CO2 utilization, energy efficiency, and product selectivity. In this work, we have developed a new electrochemical process for direct conversion of CO2 to ethylene at intermediate temperatures (350-500°C) in an electrochemical membrane reactor. This process is based on high-performance protonic ceramic electrochemical cells (PCECs) that integrate CO2 hydrogenation reaction to produce olefins in the cathode and concurrent hydrogen generation reaction in the anode to provide hydrogen for CO2 conversion. Highly active and selective catalysts for CO2-to-olefin conversion have been identified and integrated into the PCECs. Both the catalytic and electrochemical performances of the integrated reactor system are evaluated and optimized. In contrast to the use of molecular H2 in conventional thermal catalytic pathways, the active hydrogen in PCECs could be sourced from different feedstocks including H2O, light alkanes, and ammonia, etc. This work also provides valuable insights into the selection and design of efficient catalysts for electrochemical CO2 conversion at elevated temperatures.

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Zhang, Di, Jiaoyang Wang, Peijie Zong, Yingyun Qiao et Yuanyu Tian. « Low-carbon conversion of crude oil to C₂-C₄ olefins by micro Py-GC/MS and a small-scale fluidized-bed reactor ». Journal of Physics : Conference Series 2520, n^o 1 (1 juin 2023) : 012011. http://dx.doi.org/10.1088/1742-6596/2520/1/012011.

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Abstract Green utilization of crude oil has become an important way for energy transformation in the petrochemical industry. Crude oil to aimed low-carbon (C2-C4) olefins had been conducted by micro pyrolysis-gas chromatograph/mass spectrometer (Py-GC/MS) and a small-scale fluidized-bed reactor. Fe-modified Al2O3/USY catalysts were used in the catalytic pyrolysis of crude oil. The results showed that product distribution altered hugely after Fe incorporation. Suitable incorporation of Fe can promote the conversion of crude oil, while excessive Fe incorporation could reduce the yield of light olefins. Bifunctional 1%Fe/USY catalyst showed good catalytic dehydrogenation pyrolysis activity in light olefin production, which could guide the clean and low-carbon conversion of crude oil.

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Wen, Yuan, Chenliang Zhou, Linfei Yu, Qiang Zhang, Wenxiu He et Quansheng Liu. « Research Progress on the Effects of Support and Support Modification on the FTO Reaction Performance of Fe-Based Catalysts ». Molecules 28, n^o 23 (24 novembre 2023) : 7749. http://dx.doi.org/10.3390/molecules28237749.

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In recent years, the non-petroleum production of light olefins has been the research focus of Fischer–Tropsch olefin synthesis (FTO). Iron-based catalysts have attracted much attention because of their low price, high catalytic activity, and wide temperature range. In this paper, traditional modification, hydrophobic modification, and amphiphobic modification of the catalyst are summarized and analyzed. It was found that traditional modification (changing the pore size and surface pH of the catalyst) will reduce the dispersion of Fe, change the active center of the catalyst, and improve the selectivity of light olefins (for example, SiO2: 32%). However, compared with functional methods, these traditional methods lead to poor stability and high carbon dioxide selectivity (for example, SiO2: 34%). Hydrophobic modification can inhibit the adsorption and retention of water molecules on the catalyst and reduce the local water pressure near the iron species in the nuclear layer, thus inhibiting the further formation of CO2 (for example, SiO2: 5%) of the WGSR. Amphiphobic modification can not only inhibit the WGSR, but also reduce the steric hindrance of the catalyst, increase the diffusion rate of olefins, and inhibit the reabsorption of olefins. Follow-up research should focus on these issues.

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Reinikainen, Matti, Aki Braunschweiler, Sampsa Korpilo, Pekka Simell et Ville Alopaeus. « Two-Step Conversion of CO2 to Light Olefins : Laboratory-Scale Demonstration and Scale-Up Considerations ». ChemEngineering 6, n^o 6 (6 décembre 2022) : 96. http://dx.doi.org/10.3390/chemengineering6060096.

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The highly selective production of light olefins from CO2 was demonstrated for the first time with a laboratory-scale process comprising consecutive reverse water gas shift (RWGS) and Fischer–Tropsch (FT) reactors. The RWGS reaction, catalyzed by rhodium washcoated catalyst at 850 °C yielded good quality syngas with conversion values close to the thermodynamic equilibrium and without experiencing catalyst deactivation from carbon formation or sintering. For the FT synthesis, a packed bed Fe-Na-S/α-Al2O3 catalyst was used. The highest light olefin selectivity observed for the FT-synthesis was 52% at 310 °C, GHSV of 2250 h−1 and H2/CO ratio of 1. However, the optimal conditions for the light olefin production were determined to be at 340 °C, a GHSV of 3400 h−1 and a H2/CO ratio of 2, as the CO conversion was markedly higher, while the light olefin selectivity remained at a suitably high level. In addition to the experimental results, considerations for the further optimization and development of the system are presented. The combined RWGS–FT process seems to work reasonably well, and initial data for basic process design and modeling were produced.

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Liu, Fei, Ting Li, Peng Long Ye, Jian Xin Cao et Duan Hua Guo. « Influence of Parameters on Catalytic Performance over Different Modified ZSM-5 Zeolite for the IMTO Process ». Advanced Materials Research 648 (janvier 2013) : 143–46. http://dx.doi.org/10.4028/www.scientific.net/amr.648.143.

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The methanol to olefin with iodide method (IMTO) is a potential and alternative route for its mild process conditions, which produces methyl iodide as intermediate. Methanol can be highly converted, yielding high rates of selectivity to light olefins, by its reaction over varies modified ZSM-5 zeolites. Efforts have been taken to optimize the reaction with respect to selectivity of olefin and conversion of methanol. Based on the analysis of gas chromatography, the following operating conditions were obtained: 250 °C of reaction temperature, CH3OH:HI:H2O=1:1:3 of the molar ratio of raw materials, 2.5 h-1 of methanol space velocity and 30 ml•min-1 of nitrogen low rate.

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Vu, Xuan Hoan, Sura Nguyen, Thanh Tung Dang et Udo Armbruster. « Production of renewable biofuels and chemicals by processing bio-feedstock in conventional petroleum refineries ». Journal of Vietnamese Environment 6, n^o 3 (5 novembre 2014) : 270–75. http://dx.doi.org/10.13141/jve.vol6.no3.pp270-275.

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The influence of catalyst characteristics, i.e., acidity and porosity on the product distribution in the cracking of triglyceride-rich biomass under fluid catalytic cracking (FCC) conditions is reported. It has found that the degradation degree of triglyceride molecules is strongly dependent on the catalysts’ acidity. The higher density of acid sites enhances the conversion of triglycerides to lighter products such as gaseous products and gasoline-range hydrocarbons. The formation of gasoline-range aromatics and light olefins (propene and ethene) is favored in the medium pore channel of H-ZSM-5. On the other hand, heavier olefins such as gasoline-range and C4 olefins are formed preferentially in the large pore structure of zeolite Y based FCC catalyst (Midas-BSR). With both catalysts, triglyceride molecules are mainly converted to a mixture of hydrocarbons, which can be used as liquid fuels and platform chemicals. Hence, the utilization of the existing FCC units in conventional petroleum refineries for processing of triglyceride based feedstock, in particular waste cooking oil may open the way for production of renewable liquid fuels and chemicals in the near future. Bài báo trình bày kết quả nghiên cứu khả năng tích hợp sản xuất nhiên liệu sinh học và hóa phẩm từ nguồn nguyên liệu tái tạo sinh khối giầu triglyceride bằng công nghệ cracking xúc tác tấng sôi (FCC) trong nhà máy lọc dầu. Kết quả nghiên cứu cho thấy xúc tác có ảnh hưởng mạnh đến hiệu quả chuyển hóa triglyceride thành hydrocarbon. Tính acid của xúc tác càng mạnh thì độ chuyển hóa càng cao và thu được nhiều sản phẩm nhẹ hơn như xăng và các olefin nhẹ. Xúc tác vi mao quản trung bình như H-ZSM-5 có độ chọn lọc cao với hợp chất vòng thơm thuộc phân đoạn xăng và olefin nhẹ như propylen và ethylen. Với kích thước vi mao quản lớn, xúc tác công nghiệp FCC dựa trên zeolite Y ưu tiên hình thành C4 olefins và các olefin trong phân đoạn xăng. Ở điều kiện phản ứng của quá trình FCC, triglyceride chuyển hóa hiệu quả thành hydrocarbon mà có thể sử dụng làm xăng sinh học cho động cơ và olefin nhẹ làm nguyên liệu cho tổng hợp hóa dầu.

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Kianfar, Ehsan. « Comparison and assessment of zeolite catalysts performance dimethyl ether and light olefins production through methanol : a review ». Reviews in Inorganic Chemistry 39, n^o 3 (27 août 2019) : 157–77. http://dx.doi.org/10.1515/revic-2019-0001.

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AbstractThe present review focuses on a comparison and assessment of zeolite catalyst performance of dimethyl ether and light olefin production through methanol. Dimethyl ether is a clean fuel which needs diverse processes to be produced. Methanol to dimethyl ether is a very novel process which offers considerable advantages versus additional processes for the production of dimethyl ether. The corresponding fixed-bed reactors compose the most important section of such a process. Production of dimethyl ether by the mentioned process is of high importance since it can be catalytically transferred to a substance with the value of propylene. Furthermore, in case of capability to transfer low-purity methanol into dimethyl ether, less expensive methanol can be consequently achieved with higher value added. In the petrochemical industry, light olefins, for example, ethylene and propylene, can be used as raw materials for the production of polyolefin. The present review aims to produce dimethyl ether in order to reach olefin substances, initially conducting a compressive assessment on production methods of olefin substances.

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Ma, Haowei. « TreatmentImprovements of Catalysts for Higher Yield of Catalytic Cracking ». MATEC Web of Conferences 386 (2023) : 01004. http://dx.doi.org/10.1051/matecconf/202338601004.

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Catalytic cracking is the major source of light olefins. And it is proved that some aromatics can also be obtained via catalytic cracking. Products are always impacted by many factors, especially catalysts. After a long time of development of industrial and commercial catalysts, a general kind of catalysts used in FCC (Fluid Catalytic Cracking) process is molecular sieves. Zeolites molecular sieves are normally applied to enhance the products of light olefins and BTX(Benzene-Toluene-Xylene). This paper highlights some methods to improve the zeolites from different perspectives based on those conditions that can affect zeolites. Some characteristics are discussed like structure, acid sites, acidity, etc. Besides, the cost of synthesis and regeneration should be considered as well. Some ideas about the modification of zeolites are summarized in this article like ion exchange of zeolites by rare earth metals or acids, which all prove the great success of improvements of zeolites. Olefin and BTX production increase effectively with these modified catalysts. There will be more kinds of catalysts in the future by combinations and modifications.

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Xia, Wei, Qi Sun, Shang Wen Liu, Lin Ping Qiang et Yuan Cun Cui. « SAPO-34/SiO₂ Catalysts for the Transformation of Ethanol into Propylene ». Advanced Materials Research 1004-1005 (août 2014) : 707–10. http://dx.doi.org/10.4028/www.scientific.net/amr.1004-1005.707.

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Ethanol has great potential to be a candidate for the source of light olefins such as ethylene and propylene. However, ethanol to olefin (ETO) process has not been fully investigated. In this work, the conversion reactions of ethanol were carried out at 673 K under atmospheric pressure on SAPO-34 and SAPO-34/SiO2 catalysts. SAPO-34 and SAPO-34/SiO2 exhibit higher selectivity for propylene than H-ZSM-5 zeolite catalysts do. The SAPO-34 with silica binder showed better catalytic performance for the transformation of ethanol to propylene than the SAPO-34 catalyst.

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Zhang, Xiaoqiao, Jianhong Gong, Xiaoli Wei et Lingtao Liu. « Increased Light Olefin Production by Sequential Dehydrogenation and Cracking Reactions ». Catalysts 12, n^o 11 (17 novembre 2022) : 1457. http://dx.doi.org/10.3390/catal12111457.

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In this study, a sequential reaction using selected metal oxides, followed by ZSM-5-based catalysts, was employed to demonstrate a promising route for enhancing light olefin production in the catalytic cracking of naphtha. The rationale for the reaction is based on the induction of alkenes into hydrocarbon feeds prior to cracking. The optimum olefin induction was achieved by carefully optimizing the dehydrogenation active sites Mo/Al2O3 catalyst. The formed alkenes have a lower activation energy for C-H/C-C bond breaking compared to alkanes. This could accelerate the formation of carbenium ions, thus promoting the conversion of n-octane to produce light olefins. Detailed product distribution and DFT calculation indicated a remarkable increase in ethylene and propylene production in the final product through a modified reaction pathway. Compared with the common metal-promoted zeolite catalysts, the new route could avoid the block of zeolite channels and corresponding decreased catalytic cracking activity. The feasibility of the proposed route was confirmed with different ratios of dehydrogenation catalyst to the reactant. The highest yields of ethylene and propylene reached 13.22% and 33.12% with ratios of Mo/Al2O3 and ZSM-5-based catalyst to n-octane both 10:1 at 600 °C. Stability tests showed that the catalytic activity of the double-bed system was stable over 10 cycles.

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Yamaguchi, Eiji, Wakako Tanaka et Akichika Itoh. « Olefin Bifunctionalization : A Visible-light Photoredox-catalyzed Aryl Alkoxylation of Olefins ». Chemistry - An Asian Journal 14, n^o 1 (6 décembre 2018) : 121–24. http://dx.doi.org/10.1002/asia.201801211.

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Xia, Wei, Qi Sun, Shang Wen Liu, Lin Ping Qiang et Yuan Cun Cui. « Effect of Si/Al₂ Ratio on Catalytic Performance of HZSM-5 Zeolites for Conversion of Ethanol to Propylene ». Advanced Materials Research 953-954 (juin 2014) : 1121–24. http://dx.doi.org/10.4028/www.scientific.net/amr.953-954.1121.

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Ethanol has great potential to be a candidate for the source of light olefins such as ethylene and propylene. However, ethanol to olefin (ETO) process has not been fully investigated. In this work, the conversion of ethanol to propylene was investigated over H-ZSM-5 zeolite catalysts with different Si/Al2 ratios (80 and 280). Similar product distributions were obtained with the two catalysts at different contact times, and the turnover frequencies of the two catalysts were identical. These results strongly imply that the product distribution was independent of the Si/Al2 ratio and that the active site for conversion of ethanol to propylene was the identical for both catalysts.

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Jiao, Feng, Bing Bai, Gen Li, Xiulian Pan, Yihan Ye, Shengcheng Qu, Changqi Xu et al. « Disentangling the activity-selectivity trade-off in catalytic conversion of syngas to light olefins ». Science 380, n^o 6646 (19 mai 2023) : 727–30. http://dx.doi.org/10.1126/science.adg2491.

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Breaking the trade-off between activity and selectivity has been a long-standing challenge in the field of catalysis. We demonstrate the importance of disentangling the target reaction from the secondary reactions for the case of direct syngas conversion to light olefins by incorporating germanium-substituted AlPO-18 within the framework of the metal oxide–zeolite (OXZEO) catalyst concept. The attenuated strength of the catalytically active Brønsted acid sites allows enhancing the targeted carbon-carbon coupling of ketene intermediates to form olefins by increasing the active site density while inhibiting secondary reactions that consume the olefins. Thus, a light-olefins selectivity of 83% among hydrocarbons and carbon monoxide conversion of 85% were obtained simultaneously, leading to an unprecedented light-olefins yield of 48% versus current reported light-olefins yields of ≤27%.

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Rabeeah Taj, Rabeeah Taj, Erum Pervaiz Erum Pervaiz et Arshad Hussain Arshad Hussain. « Synthesis and Catalytic Activity of IM-5 Zeolite as Naphtha Cracking Catalyst for Light Olefins : A Review ». Journal of the chemical society of pakistan 42, n^o 2 (2020) : 305. http://dx.doi.org/10.52568/000637.

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Light olefins are the backbone of modern industrialization. Olefins are used as feedstock for production of various industrial products such as synthetic fibers, construction materials, textiles, rubber and other chemicals in the petrochemical industry. For more than a half-century, steam/thermal hydrocarbon cracking is considered as the main route and conventional process for light olefins yield. Few drawbacks of conventional steam cracking such as extensive energy consumption, requirements of high temperature and pressure conditions, the difficult selectivity of particular light olefins and excess emission of CO2 relate to this technology, which cannot accommodate further needs regarding the chemical process industry. Steam cracking also poses a threat to uncontrolled heat. Catalytic cracking of hydrocarbons is highly appreciated as it is a less energy consuming (low temperature and pressure conditions) and an environment-friendly process for light olefins production. Catalytic cracking has been under consideration as a favorable alternative but still depends upon catalyst, its activity, and selectivity for a particular product. Catalytic cracking is quite beneficial for industrial scale. The present proficiency of refining and petro-chemistry to a great extent is based on highly active, selective, and durable catalysts. Various catalysts possess compositional diversity, surface area, and surface energy and hence provide a different pathway for the reaction to occur. Petroleum-extracted naphtha cracking technique now a days is the main process for light olefins yield. This review highlights the use of IM-5 zeoliteas an emerging catalyst for naphtha cracking process as compared to conventional catalysts in the last few decades. Structure, synthesis techniques and catalytic activity of IM-5 zeolite is reviewed. Different zeolites which can be used in naphtha cracking reactor and their applications in the catalytic cracking of hydrocarbons have been studied. This review provides a significant insight into catalytic activity comparison between conventional zeolites and IM-5 zeolite.

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Rabeeah Taj, Rabeeah Taj, Erum Pervaiz Erum Pervaiz et Arshad Hussain Arshad Hussain. « Synthesis and Catalytic Activity of IM-5 Zeolite as Naphtha Cracking Catalyst for Light Olefins : A Review ». Journal of the chemical society of pakistan 42, n^o 2 (2020) : 305. http://dx.doi.org/10.52568/000637/jcsp/42.02.2020.

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Light olefins are the backbone of modern industrialization. Olefins are used as feedstock for production of various industrial products such as synthetic fibers, construction materials, textiles, rubber and other chemicals in the petrochemical industry. For more than a half-century, steam/thermal hydrocarbon cracking is considered as the main route and conventional process for light olefins yield. Few drawbacks of conventional steam cracking such as extensive energy consumption, requirements of high temperature and pressure conditions, the difficult selectivity of particular light olefins and excess emission of CO2 relate to this technology, which cannot accommodate further needs regarding the chemical process industry. Steam cracking also poses a threat to uncontrolled heat. Catalytic cracking of hydrocarbons is highly appreciated as it is a less energy consuming (low temperature and pressure conditions) and an environment-friendly process for light olefins production. Catalytic cracking has been under consideration as a favorable alternative but still depends upon catalyst, its activity, and selectivity for a particular product. Catalytic cracking is quite beneficial for industrial scale. The present proficiency of refining and petro-chemistry to a great extent is based on highly active, selective, and durable catalysts. Various catalysts possess compositional diversity, surface area, and surface energy and hence provide a different pathway for the reaction to occur. Petroleum-extracted naphtha cracking technique now a days is the main process for light olefins yield. This review highlights the use of IM-5 zeoliteas an emerging catalyst for naphtha cracking process as compared to conventional catalysts in the last few decades. Structure, synthesis techniques and catalytic activity of IM-5 zeolite is reviewed. Different zeolites which can be used in naphtha cracking reactor and their applications in the catalytic cracking of hydrocarbons have been studied. This review provides a significant insight into catalytic activity comparison between conventional zeolites and IM-5 zeolite.

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Erkmen, Berrak, Adem Ozdogan, Ayhan Ezdesir et Gokhan Celik. « Can Pyrolysis Oil Be Used as a Feedstock to Close the Gap in the Circular Economy of Polyolefins ? » Polymers 15, n^o 4 (9 février 2023) : 859. http://dx.doi.org/10.3390/polym15040859.

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Plastics are engineering marvels that have found widespread use in all aspects of modern life. However, poor waste management practices and inefficient recycling technologies, along with their extremely high durability, have caused one of the major environmental problems facing humankind: waste plastic pollution. The upcycling of waste plastics to chemical feedstock to produce virgin plastics has emerged as a viable option to mitigate the adverse effects of plastic pollution and close the gap in the circular economy of plastics. Pyrolysis is considered a chemical recycling technology to upcycle waste plastics. Yet, whether pyrolysis as a stand-alone technology can achieve true circularity or not requires further investigation. In this study, we analyzed and critically evaluated whether oil obtained from the non-catalytic pyrolysis of virgin polypropylene (PP) can be used as a feedstock for naphtha crackers to produce olefins, and subsequently polyolefins, without undermining the circular economy and resource efficiency. Two different pyrolysis oils were obtained from a pyrolysis plant and compared with light and heavy naphtha by a combination of physical and chromatographic methods, in accordance with established standards. The results demonstrate that pyrolysis oil consists of mostly cyclic olefins with a bromine number of 85 to 304, whereas light naphtha consists of mostly paraffinic hydrocarbons with a very low olefinic content and a bromine number around 1. Owing to the compositional differences, pyrolysis oil studied herein is completely different than naphtha in terms of hydrocarbon composition and cannot be used as a feedstock for commercial naphtha crackers to produce olefins. The findings are of particular importance to evaluating different chemical recycling opportunities with respect to true circularity and may serve as a benchmark to determine whether liquids obtained from different polyolefin recycling technologies are compatible with existing industrial steam crackers’ feedstock.

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Mohd Sofi, Muhammad Hafizuddin, et Muhamed Yusuf Shahul Hamid. « Alteration of acidity and porosity of Beta zeolite using fibrous silica for light olefin production ». E3S Web of Conferences 516 (2024) : 02003. http://dx.doi.org/10.1051/e3sconf/202451602003.

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Traditional olefin production heavily depends on fossil fuels, which are a significant contributor to environmental issues. Methanol to olefin (MTO) is among non-fossil fuel alternatives to produce olefinic products from abundant resources, such as biomass, coal, and natural gas. Nevertheless, the catalytic reaction of MTO over commercial zeolite catalysts is hindered by their low activity, mainly due to the micropore structure and excessive acidity within the zeolite. Herein, Beta zeolite with fibrous silica structure was successfully synthesized via the microemulsion and Beta seed-assisted method. The catalysts were characterized using FESEM, N2 physisorption, and ammonia-TPD. FESEM results revealed a well-ordered spherical morphology of HFBETA with uniform particle size distribution. In surface analysis, the HFBETA exhibits higher BET surface area and mesopore volume compared to commercial HBETA by 35% and 86%, respectively. The introduction of fibrous silica within the Beta structure led to a significant drop in the acidity of the catalyst, as shown in ammonia-TPD results. These led to superior catalytic performance of HFBETA in the MTO process.

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Gomes, Diana M., Patrícia Neves, Margarida M. Antunes, António J. S. Fernandes, Martyn Pillinger et Anabela A. Valente. « Post-Synthesis Strategies to Prepare Mesostructured and Hierarchical Silicates for Liquid Phase Catalytic Epoxidation ». Catalysts 12, n^o 12 (25 novembre 2022) : 1513. http://dx.doi.org/10.3390/catal12121513.

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Olefin epoxidation is an important transformation for the chemical valorization of olefins, which may derive from renewable sources or domestic/industrial waste. Different post-synthesis strategies were employed to introduce molybdenum species into mesostructured and hierarchical micro-mesoporous catalysts of the type TUD-1 and BEA, respectively, to confer epoxidation activity for the conversion of relatively bulky olefins (e.g., biobased methyl oleate, DL-limonene) to epoxide products, using tert-butyl hydroperoxide as an oxidant. The influences of (i) the type of metal precursor, (ii) type of post-synthesis impregnation method, (iii) type of support and (iv) top-down versus bottom-up synthesis methodologies were studied to achieve superior catalytic performances. Higher epoxidation activity was achieved for a material prepared via (post-synthesis) incipient wetness impregnation of MoO2(acac)2 (acac = acetylacetonate) on (pre-treated) siliceous TUD-1 and calcination; for example, methyl oleate was converted to the corresponding epoxide with 100% selectivity at 89% conversion (70 °C). Catalytic and solid-state characterization studies were conducted to shed light on material stability phenomena.

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Ulfiati, Ratu. « CATALYTIC PERFORMANCE OF ZSM-5 ZEOLITE IN HEAVY HYDROCARBON CATALYTIC CRACKING : A REVIEW ». Scientific Contributions Oil and Gas 42, n^o 1 (6 août 2020) : 29–34. http://dx.doi.org/10.29017/scog.42.1.384.

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Low quality heavy oils and residues, which are subsequently obtained by processing heavy crudes, are considered as alternate suitable source for transportation fuels, energy and petrochemicals. ZSM-5 zeolite with high Si/Al ratio and modified with phosphorous and La has showed not only high selectivity to light olefins but also high hydrothermal stability for the steam catalytic cracking of naphtha. Kaolin is promising natural resource as raw material to synthesis of ZSM-5 zeolite. The utilization of acid catalysts with large pore size or hierarchically structured and high hydrothermal stability to resist the severity of the steam catalytic cracking (or thermal and catalytic cracking) operation conditions to maximize the olefin production.

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Russell, Christopher K., Josiah L. Rockey, Rebecca N. Hanna et Jeffrey T. Miller. « Impact of Co-Fed Hydrogen on High Conversion Propylene Aromatization on H-ZSM-5 and Ga/H-ZSM-5 ». Catalysts 14, n^o 7 (27 juin 2024) : 405. http://dx.doi.org/10.3390/catal14070405.

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The expanded production of shale gas has increased the desire for developing methods for converting light alkanes, especially propane and ethane, into aromatic compounds (i.e., benzene, toluene, and xylene) for petrochemicals and fuels. The Cyclar process is one example of an industrial process that has been demonstrated for the conversion of butane to aromatics; however, the conversion of lower molecular weight alkanes remains elusive. A multi-step process for the conversion of light alkanes to aromatics may be developed, where the first stage converts light alkanes into olefins and hydrogen, and the second stage converts olefins into aromatics. However, to determine the viability of this process, a better understanding of the performance of olefin aromatization in the presence of equimolar hydrogen is necessary. Herein, H-ZSM-5 and Ga-modified H-ZSM-5 are compared for propylene aromatization in the presence and absence of equimolar hydrogen at 1.9 kPa and 50 kPa partial pressures. The presence of H2 has no impact on the product distribution with H-ZSM-5 at either pressure. At 1.9 kPa with Ga/H-ZSM-5, similar product distributions are observed regardless of the presence or absence of H2 since Ga is not sufficiently active for hydrogenation to inhibit aromatics formation. However, at 50 kPa of H2 with Ga/H-ZSM-5, there is an increased selectivity to C4 products and a decrease in toluene and xylene selectivities at high conversions (i.e., χ > 80%), suggesting that aromatic dehydrogenation of cyclic hydrocarbons has been suppressed.

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Paleta, Oldřich, Jaroslav Kvíčala, Zuzana Budková et Hans-Joachim Timpe. « Radical Additions to Fluoroolefins : Experimental Evidence for a Free-Radical Chain Mechanism in the Photo-Initiated Addition of Alcohols to Fluoroolefins ». Collection of Czechoslovak Chemical Communications 60, n^o 4 (1995) : 636–44. http://dx.doi.org/10.1135/cccc19950636.

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Photo-initiated addition of 2-propanol to two fluoroolefinic compounds, i.e. methyl 2,4,4,5,6,6-hexafluoro-3-oxa-2-(trifluoromethyl)hex-5-enoate (IV) containing perfluoroallyloxy group and 8,9-dichloro-1,1,2,4,4,5,7,7,8,9,9-undecafluoro-3,6-dioxa-5-(t rifluoromethyl)dodec-1-ene (V) containing trifluorovinyloxy group were used to verify a free-radical chain mechanism by means of quantum yield measurements based on substrate-decay kinetic. UV-Light energy (254 nm) was transferred to the reaction system via triplet-excited acetone. Quantum yields Fi of the addition products (X, XI) reached values 68 and 42, respectively, and thus confirmed the chain mechanism. The olefinic compounds IV and V were synthesized on the basis of the reaction of 2,3-dichloro-2,3,3-trifluoropropanoyl fluoride (I) with hexafluoropropene-1,2-oxide. The photoaddition of 2-propanol to both olefins took place with complete regioselectivity.

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Hidalgo, José, Michal Zbuzek, Radek Černý et Petr Jíša. « Current uses and trends in catalytic isomerization, alkylation and etherification processes to improve gasoline quality ». Open Chemistry 12, n^o 1 (1 janvier 2014) : 1–13. http://dx.doi.org/10.2478/s11532-013-0354-9.

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AbstractDue to the growing restrictions on the content of aromatic compounds by the European legislation in motor fuels and at the same time the need for higher quality fuels (minimizing the presence of contaminants and hazardous products to health), it has become necessary to increase processes that can maximize the number of octane in gasoline. This manuscript is aimed to provide current trends and processes related to isomerization, alkylation and etherification processes to improve gasolines as final product. Examples provided include the isomerization of light n-alkanes into iso-alkanes or the alkylation, in which the preferred olefin is the methylbutilene and i-butane to produce a high octane number gasoline. Currently, there are two main commercial processes for alkylation processes (hydrofluoric and sulfuric acid technologies). Other incoming suitable process is the etherification of iso-olefins to bio-ethers (the European Union have as a minimum target of biofuel content in fuels of 10% in 2020). The refiners are recently investing in the production of bio-ETBE (ethyl tertiary butyl ether) and other products as additives using bio-ethanol and olefins. Commercial and new potential catalysts for all these processes are currently being used and under investigation.

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Sharanda, M. E., A. M. Mylin, O. Yu Zinchenko et V. V. Brei. « Hydrogenation of C`'5 olefins in vapor phase on the copper oxide catalyst ». Catalysis and Petrochemistry, n^o 32 (2021) : 93–98. http://dx.doi.org/10.15407/kataliz2021.32.093.

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Hydrogenation of unsaturated hydrocarbons is one of the important processes of the modern petrochemical industry. Quite large amount of C4-5 fractions of hydrocarbons containing paraffins and olefins are formed via pyrolysis of light petroleum products. To increase the production of ethylene and propylene, the separated C4-5 fractions are recycled for pyrolysis. Preliminary hydrogenation of olefin compounds in these fractions is necessary. Preferably, the hydrogenation is carried out in the liquid phase at temperatures of 40 – 80 °C under hydrogen pressure up to 15 bar overhigh-cost palladium-containing catalysts. The aim of this work was to elucidate the possibility of efficient hydrogenation of industrial С5 fraction containing C`5 olefins over some mixed copper-oxide catalysts. Hydrogenation of C`5 fraction of pyrolysis of light petroleum products in the vapor phase over such catalysts as CuO-ZnO-ZrO2-Al2O3 and CuO-ZnOAl2O3 in comparison with commercial Pd/Al2O3 catalyst for C4-5 olefins hydrogenation have been studied. The pyrolysis C`5 fraction containing 51 wt. % of unsaturated hydrocarbons (2-methyl-1-butene, 2-pentene, cis-2-pentene, trans-2-pentene, 2-methyl-2-butene) was used in the work. The catalytic process was carried out in a reactor with a fixed catalyst bed at 170 – 190 oC, and a pressure of 1.1 – 2.5 MPa. Analysis of obtained products was provided by gas-chromatography (Agilent 7820A) and 13C NMR (Bruker Avance 400) methods. It is shown that the hydrogenation of olefins with conversion of the C`5 fraction such high as 98 – 99 % can be carried out in the vapor phase over CuO-ZnO-Al2O3 and CuO-ZnO-Al2O3 catalysts at the temperature of 180 oC and pressure 1.2 – 1.5 MPa. The total C5 olefinsloading can reach 15 – 23 mmol/gcat/h. The residual content of unsaturated hydrocarbons is 1 %. At the pressure of 2.5 MPa, a sharp decrease in conversion is observed, as n-pentane turns into a liquid phase. Catalyst deactivation was not observed for 36 hours. Under the same conditions the drop in activity of industrial catalyst 0.35 % Pd/Al2O3 was observed after 70 minutes from the start of work.

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Yongmei, Zhang, et You Hongjun. « Catalytic Oxidation of Olefins ». Open Fuels & ; Energy Science Journal 4, n^o 1 (14 octobre 2011) : 9–11. http://dx.doi.org/10.2174/1876973x01104010009.

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This paper introduces the development circumstance of catalytic oxidation of olefins. And the synthesis method of catalytic oxidation of olefins are discussed in detail, such as, catalytic gas-phase oxidation of olefins; catalytic liquidphase oxidation of olefins; catalytic oxidation of enzyme; catalytic oxidation of olefins by using sodium hypochlorite and hydrogen peroxide as the catalyst; directly catalytic oxidation of olefins by using visible light. When hydrogen peroxide is used as the catalyst, it has no pollution and is good beneficial to the public.

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Liu, Sibao, Bofeng Zhang et Guozhu Liu. « Metal-based catalysts for the non-oxidative dehydrogenation of light alkanes to light olefins ». Reaction Chemistry & ; Engineering 6, n^o 1 (2021) : 9–26. http://dx.doi.org/10.1039/d0re00381f.

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Yang, Lin, Jing Li et Jian Xin Cao. « Synthesis of Light Olefins from CO₂Hydrogenation on Fe/ZSM-5 Catalyst ». Applied Mechanics and Materials 423-426 (septembre 2013) : 463–66. http://dx.doi.org/10.4028/www.scientific.net/amm.423-426.463.

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A Fe/ZSM-5 catalyst was prepared by impregnation method and evaluated in the synthesis of light olefins from CO2 hydrogenation. It is found that The conversion of CO2, the yield of light olefins and hydrocarbons content reach 82.42%, 12.65%, 0.4885mol respectively under the conditions as follow, mass concentration of ferric nitrate 9%, silica to alumina ratio 25, calcination temperature of the catalyst 500°C. By the studies of NH3 temperature programmed desorption, performance changes of the catalysts was analysis. A possible mechanism is proposed on the basis of mineral composition changes of Fe/ZSM-5 catalyst in the synthesis of light olefins through XRD analysis.

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Ferreira, Leonildo A., Yuri C. A. Sokolovicz, Júlia L. Couto et Henri S. Schrekker. « Tandem olefin isomerization/metathesis and volatiles capture : Accessing light olefin blends and broadening the scope to higher olefins ». Molecular Catalysis 460 (décembre 2018) : 36–39. http://dx.doi.org/10.1016/j.mcat.2018.09.006.

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Ni, Zhijiang, Xiaoyu Chen, Lin Su, Hanyu Shen et Chaochuang Yin. « Effect of Calcination Temperature in Large-Aperture Medium-Entropy Oxide (FeCoCuZnNa)O on CO2 Hydrogenation for Light Olefins ». Catalysts 14, n^o 11 (13 novembre 2024) : 818. http://dx.doi.org/10.3390/catal14110818.

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The catalytic hydrogenation of carbon dioxide is not only a way to mitigate the greenhouse effect but also provides high-value chemicals. In this work, a medium-entropy oxide catalyst (FeCoCuZnNa)O was prepared by the sol–gel method for highly active and selective hydrogenation of CO2 to value-added hydrocarbons. When reacted at 290 °C, 2.5 MPa, and 2500 mL·gcat−1·h−1, the CO2 conversion and selectivity of olefin were affected by the calcination temperature of the catalyst, and the best performances were 39% and 41.3%. The large pore size and oxygen vacancies (Ov) formed by (FeCoCuZnNa)O promote the activation of CO2 and promote the C-C coupling reaction of Fe5C2 in a hydrogenation reaction. The promoted C-C coupling reaction was related to the surface enrichment of iron species. The presence of Ov also inhibited the excessive hydrogenation reaction, further improving the selectivity of light olefins. In addition, (FeCoCuZnNa)O did not show significant deactivation within 75 h, indicating that the catalyst has strong industrial potential.

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Casadevall, Carla, David Pascual, Jordi Aragón, Arnau Call, Alicia Casitas, Irene Casademont-Reig et Julio Lloret-Fillol. « Light-driven reduction of aromatic olefins in aqueous media catalysed by aminopyridine cobalt complexes ». Chemical Science 13, n^o 15 (2022) : 4270–82. http://dx.doi.org/10.1039/d1sc06608k.

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A dual catalytic system based on earth-abundant elements reduces aryl olefins to alkanes in aqueous media under visible light. Mechanistic studies allow for rational tunning of the system for the selective reduction of aryl olefins vs ketones and vice versa.

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Lari, Tahereh Taherzadeh, Ali Akbar Mirzaei, Hossein Atashi et Hamid Reza Bozorgzadeh. « A Modeling Study of Operating Conditions and Different Supports on Fe-Co-Ce Nanocatalyst and Optimizing of Light Olefins Selectivity in the Fischer-Tropsch Synthesis ». Chemistry & ; Chemical Technology 15, n^o 2 (15 mai 2021) : 170–82. http://dx.doi.org/10.23939/chcht15.02.170.

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This study demonstrates the effect of operating conditions (Red-GHSV, inlet H2/CO, Oprat-GHSV) and the effect of Fe-Co-Ce nanocatalyst support. A statistical model using the response surface methodology (RSM) was applied with the target of achieving higher olefins selectivity in Fischer-Tropsch synthesis, which indicates the interaction effects of factors. The conditions under which three objectives optimization for maximizing olefins and minimizing paraffins and methane were determined. Synthesized nanocatalysts with various supports were characterized by XRD, SEM and TPR techniques

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Ping, Guichen, Kai Zheng, Qihua Fang et Gao Li. « Composite Nanostructure of Manganese Cluster and CHA-Type Silicoaluminaphosphates : Enhanced Catalytic Performance in Dimethylether to Light Olefins Conversion ». Nanomaterials 11, n^o 1 (24 décembre 2020) : 24. http://dx.doi.org/10.3390/nano11010024.

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Light olefins, especially ethylene and propylene, are important chemicals in petrochemical industries with an increasing demand and play an essential role in the global consumption. In this regard, there have been extensive studies to design efficient catalysts for the light olefins productions. In this study, we report a new protocol to induce Mn nanoclusters (MnNC) into the mesopore of a CHA-type silicoaluminaphosphates via a one-pot synthesis of MnNC@SAPO-34 catalysts. The catalysts are characterized by a series of technology, such as TEM, XRD, NH3-TPD, 27Al MAS NMR, ICP-MS, XPS, and as well as N2-physical adsorption methods. The Mn nanoclusters of Mn2O3 and MnO2 species are well dispersed in the framework of the SAPO-34 silicoaluminaphosphates, modifying the porosity and acidic property of the SAPO-34: Giving rise to more mesoporous and improving the acid density. The MnNC@SAPO-34 catalysts exhibit decent 100% conversion and 92.2% olefins selectivity in the dimethyl ether to olefins (DTO) reactions, which is considerably higher than that for SAPO-34 silicoaluminaphosphates (79.6% olefins selectivity). The higher olefins selectivity over the MnNC@SAPO-34 is deemed to associate with the strong acid density and intensity of the silicoaluminaphosphates. Further, the Mn particles largely improve silicoaluminaphosphates’s durability.

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SCOFIELD, C. F., E. BENAZZI, H. CAUFFRIEZ et C. MARCILLY. « Metylcyclohexane conversion to light olefins ». Brazilian Journal of Chemical Engineering 15, n^o 2 (juin 1998) : 218–24. http://dx.doi.org/10.1590/s0104-66321998000200018.

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