High Light Olefins Research Articles

Boosting CO2 hydrogenation of Fe-based monolithic catalysts via 3D printing technology-induced heat/mass-transfer enhancements

Boosting CO2 hydrogenation of Fe-based monolithic catalysts via 3D printing technology-induced heat/mass-transfer enhancements

Unraveling the role of GaZrOx structure and oxygen vacancy in bifunctional catalyst for highly active and selective conversion of syngas into light olefins

The direct conversion of syngas to light olefins (STO) over metal oxide-zeolite (OX-ZEO) bifunctional catalyst has aroused wide interest. However, due to unmatched reaction temperature for CO conversion to oxygenated hydrocarbons over metal oxide (200−300 °C) and C−C coupling reaction over zeolite (350−450 °C), it is still a great challenge to achieve both high light olefins selectivity and high CO conversion; moreover, the reaction mechanism needs to be further studied. Herein, the Ga-Zr oxide is taken as a probe oxide to mix with SAPO-34 zeolite for STO. A high light olefins selectivity of 88.6% is achieved at an extremely high CO conversion of 51.6% with a stable activity for 200 h. The incorporation of Ga into ZrO2 generates the GaZrOx solid solution structure with abundant concentration of oxygen vacancy and hydroxy group, the strong synergetic effect between Ga and Zr in GaZrOx benefits the CO activation and CH3O* formation at high temperatures (280−430°C), providing a compatible temperature match for C−C coupling over SAPO-34. The GaZrOx is a promising and potential catalyst for industrial application in direct conversion of syngas to olefins, aromatics, and liquid fuels.

Tuning Fischer-Tropsch synthesis product distribution toward light olefins over nitrided Fe-Mn bimetallic catalysts

Tuning Fischer-Tropsch synthesis product distribution toward light olefins over nitrided Fe-Mn bimetallic catalysts

Core-shell SAPO-34@ZSM-5 composite via in situ solid-solid transformation of pre-coating MCM-41 shell and its application in methanol-to-olefins

Core-shell SAPO-34@ZSM-5 composite via in situ solid-solid transformation of pre-coating MCM-41 shell and its application in methanol-to-olefins

Methanol‐to‐Light Olefins Reaction using Zn‐Ag Modified SSZ‐13 Catalyst

AbstractThe 2 wt.% of Zn and Ag (Zn1‐x‐Agx; x=0.2, 0.4, 0.6 %) modified SSZ‐13 (SZ‐13) zeolite was prepared by wet‐impregnation method, and its catalytic activity was demonstrated for methanol‐to‐olefin (MTO). The Zn0.6‐Ag0.4/SZ‐13 catalyst exhibited high catalytic activity due to change in properties of catalyst. The Zn particles were highly dispersed inside the SZ‐13; while Ag particles were dispersed on the surface of SZ‐13, confirmed by HRTEM and surface area. The small % of Ag over SZ‐13 promotes ethylene production via aromatization of reaction, and highly dispersed Zn on SZ‐13 help to produce stable ethylene and propylene. The Zn0.6‐Ag0.4/SZ‐13 catalyst showed (∼10 %) higher light olefin (87 %) selectivity than parent SZ‐13 as well as mono metal incorporated SZ‐13. The higher catalytic activity was attributed due to effect of both metals (Zn and Ag), where Ag promotes partial aromatization on the surface, and Zn increases the Lewis acidity in the zeolite pore. This catalyst can help to improve the selectivity of light olefin using MTO reaction.

Efficient processing of crude oil using direct cracking at high temperatures over modified FCC catalysts

The direct cracking of Bach Ho crude oil, having API gravity of 41°, over equilibrium FCC catalyst (Ecat), modified FCC catalyst (HT-FCC) and ZSM-5 additive were studied at 620–650 °C using short-contact-time micro activity testing unit. HT-FCC catalyst was prepared by the treatment of Ecat with oxalic acid in reflux condition. This treatment largely improves the porosity while keeping the particle size of Ecat. Hence, it leads to an important enhancement in catalytic cracking activity. Due to high activity of HT-FCC catalyst, the direct cracking of crude oil can be performed at a low catalyst-to-oil ratio (C/O) which helps to decrease the yield of dry gas. At 620–650 °C, C/O of 1.5–2.5, 18–23 wt.% of light olefins, 3–6 wt.% of dry gas together with 51–59 wt.% of gasoline yields can be obtained with HT-FCC catalyst. ZSM-5 addition favors the conversion of gasoline to light olefins. Compared to the results reported in literature, the use of HT-FCC and ZSM-5 catalysts at 650 °C, low C/O of 1.5 shows promising performances: (i) much lower dry gas yield (8%), (ii) high light-olefins yield (32%) while maintaining high gasoline yield (43%), and (iii) high BTXs content in gasoline (45%).

Catalytic fast pyrolysis of cellulose over different metal-modified ZSM-5 zeolites for light olefins

Light olefins (C 2 H 4 , C 3 H 6 and C 4 H 8 ) are important chemical building blocks in modern energy and material system. In this study, the effects of different metal-modified ZSM-5 catalysts on the production of light olefins from cellulose fast pyrolysis were investigated in a fixed bed. Fe, La, Cu, Mg, Al and Ce modified ZSM-5 were prepared by the impregnation method, and then the derived modified ZSM-5 catalysts were characterized by different analytical instruments. The correlation between catalyst characteristics and the production of light olefins was explored. The results showed that the specific MFI-type structure of ZSM-5 remained intact after modification, and the surface area, pore volume and the amount of acid sites of catalysts varied. The highest light olefins yield was obtained over Cu-ZSM-5 (7.64 C-mol%), while the lowest was achieved over Mg-ZSM-5 (3.75 C-mol%). Moreover, the formation of light olefins can be promoted with the increasing of ZSM-5 other-pore volume and surface area, medium and strong acidity, and the decreasing of micro-pore volume and surface area, weak acidity. The results may share some light on the design of high efficiency ZSM-5 catalyst for high light olefins production. • Cellulose catalytic pyrolysis was conducted over metal-modified ZSM-5 catalysts. • Cu modified ZSM-5 exhibited the highest light olefins yield of 7.64 C-mol%. • C 2 H 4 selectivity on ZSM-5 can be promoted by Ce, La, Cu, Mg, Al in the order. • Micropore surface area and weak acidity of ZSM-5 inhibit light olefins formation.

Highly robust and efficient MnZnFe2O4 decorated fibrous KCC-SiO2 catalyst for the synthesis of light olefins from syngas

In this study, high light olefin (C2–C4) selectivity is obtained through FTS reaction and using a novel and robust catalyst of KCC-SiO2 fibrous nanospheres decorated with MnZnFe2O4 NPs.

Ge‐Substituted Hierarchical Ferrierite for n‐Pentane Cracking to Light Olefins: Mechanistic Investigations via In‐situ DRIFTS Studies and DFT Calculations

AbstractThe development of heterogeneous catalysts for light olefin production via a catalytic cracking has been crucially important due to the high demand of related products in industrial applications. Herein, we report the structural analysis of a germanium‐substituted hierarchical ferrierite zeolite obtained by one‐pot synthesis. This is the first report on an investigation of the synergistic effect of hierarchical structures and the one‐pot Ge‐substitution in a ferrierite framework on the catalytic cracking mechanism. Our findings exhibit that the existence of germanium in a hierarchical ferrierite framework can indeed reduce the Brønsted acid strength, facilitating a catalytic reaction with high light olefin selectivity (63 %) due to the elimination of side reactions, such as dimerization and aromatization, confirmed by in‐situ DRIFTS and DFT studies. This opens up the perspective of the development of metal substitution in an interconnected 8‐ and 10‐pore framework with hierarchical structures on the catalytic behaviors of light olefin production.

IM-5 zeolite with abundant narrow mesopores and modulated acidity as stable and selective cracking catalyst

High-performance IM-5 was prepared by tetrapropylammonium hydroxide (TPAOH) and NaOH alkaline treatment. The modification of combined alkaline treatment on the pore and acidity were systematically characterized. The 29 Si NMR results indicated that Si(4Si, 0Al) sites were protected by tetrapropylammonium cation (TPA + ) at low TPAOH/(NaOH + TPAOH) molar ratio, while the protection effect extended to some Si(3Si, 1Al) sites at TPAOH/(NaOH + TPAOH) ratio of 75%. And, the amount of strong Brønsted acid sites decreased significantly from 255 μmolg −1 to 119 μmolg −1 under the optimal TPAOH/NaOH alkaline treatment conditions. Compared to NaOH treatment alone, the mesopore volume and external surface area of IM-5 were further increased with TPAOH introduced, meanwhile, the mesopore size was shrunken into the range of 2–10 nm centered at 5 nm. Compared to NaOH treated IM-5 catalyst, the TPAOH/NaOH treated one exhibited higher initial light olefins yield (53.4% vs. 45.2% for n -heptane cracking) and better catalytic stability and regeneration properties. The abundant narrow mesopores contributed into high tolerance ability to coke deposition in IM-5 catalysts, as confirmed by TGA results. • TPAOH/NaOH treatment led to abundant well-spread mesopores in IM-5. • TPAOH/NaOH treatment lowered the amount of strong Brønsted acid sites. • TPA + extended protection effect to framework aluminum at high TPAOH concentration. • TPAOH/NaOH treated IM-5 reached high light olefins yield of 53.4%. • TPAOH/NaOH treated IM-5 kept stable in 5 regeneration cycles.

High-efficient hierarchical [B]-ZSM-5 catalyst by simultaneously using of CTAB surfactant and boron promoter for methanol to olefins reaction

In this work, a one-pot hydrothermal route was applied to prepare the hierarchical high-silica ZSM-5 catalyst (Si/Al = 200), including boron promoter in the structure and CTAB surfactant. XRD, FE-SEM, BET, NH3-TPD, and FT-IR techniques were applied to evaluate the physical and chemical properties. The effect of different amounts of secondary template (CTAB) and different operating conditions was studied on the ZSM-5 catalyst preparation and performance in methanol to olefins reaction. The results showed the high surface area (391.8 m2g−1), mesoporous structure, high crystallinity, and well-adjusted acidity for the modified catalyst. The prepared catalyst with CTAB/TPABr molar ratio of 1 led to the highest propylene selectivity (48.56%), the highest P/E ratio of 6.3, and the highest light olefin selectivity (71%). This improved performance can be assigned to the high surface area, short diffusion path length by mesopore structure, and optimum acidity. It was found that the optimum temperature and weight hourly space velocity were 480 °C and 7.2 h−1, respectively.

Rapid High-temperature Synthesis of Nanosized ZSM-22 Zeolite

Nanosized ZSM-22 with high crystallinity was synthesized rapidly by a high-temperature hydrothermal synthesis method. The effects of synthesis conditions such as crystallization temperature, crystallization time, Si/Al ratios and crystallinity of ZSM-22 were investigated, and the relationship between crystallization temperature and crystallization time was calculated by Arrhenius equation. Meanwhile, the rapid high-temperature synthesis method was effective to synthesize ZSM-22 with Si/Al ratio from 35 to 70. The nanosized ZSM-22 exhibited high light olefin selectivity and a long lifetime in the MTO reaction.

Directed transforming of coke to active intermediates in methanol-to-olefins catalyst to boost light olefins selectivity

Methanol-to-olefins (MTO), the most important catalytic process producing ethylene and propylene from non-oil feedstocks (coal, natural gas, biomass, CO2, etc.), is hindered by rapid catalyst deactivation due to coke deposition. Common practice to recover catalyst activity, i.e. removing coke via air combustion or steam gasification, unavoidably eliminates the active hydrocarbon pool species (HCPs) favoring light olefins formation. Density functional theory calculations and structured illumination microscopy reveal that naphthalenic cations, active HCPs enhancing ethylene production, are highly stable within SAPO-34 zeolites at high temperature. Here, we demonstrate a strategy of directly transforming coke to naphthalenic species in SAPO-34 zeolites via steam cracking. Fluidized bed reactor-regenerator pilot experiments show that an unexpectedly high light olefins selectivity of 85% is achieved in MTO reaction with 88% valuable CO and H2 and negligible CO2 as byproducts from regeneration under industrial-alike continuous operations. This strategy significantly boosts the economics and sustainability of MTO process.

Hierarchical porous spinel MFe2O4 (M=Fe, Zn, Ni and Co) nanoparticles: Facile synthesis approach and their superb stability and catalytic performance in Fischer-Tropsch synthesis

Abstract The environmental pollution problem and the dwindling in the crude oil resources have been driving considerable researches into alternative routes for the production of clean and low cost liquid fuels. Fischer-Tropsch synthesis (FTS) is a key-technology and a clean alternative for the production of valuable organic chemicals and high standard liquid fuels through the reaction of syngas (CO/H2). In this study, one-pot hydrothermal reaction was adopted for the synthesis of robust MFe2O4 (M = Fe, Zn, Ni and Co) nanoparticles (NPs) with hierarchical porous-structured. The as-synthesized NPs and without the reported necessary pre-calcination step were appointed as robust catalysts in FTS at various reaction temperature (240–290 °C). The obtained catalytic results have demonstrated that CoFe2O4 NPs catalyst with its inversed spinel structure exhibited the optimum catalytic activity compared with the type of normal spinel structure of ZnFe2O4 catalyst. More precisely, CoFe2O4 NPs catalyst showed the best CO conversion ratio of 96% at 290 °C and the highest light-olefin (C2–C4) selectivity value of 63%. However, Fe3O4 NPs catalyst displayed the highest selectivity toward long chain hydrocarbon product (C5+) of 50 wt%, and the lowest CH4 selectivity value of 12% at 260 °C. Notably, the obtained results from X-ray diffraction and N2-physisorption characterization for the spent ferrite catalysts demonstrated that the co-existence of the active sites of Hagg iron carbide (χ-Fe5C2) and metallic Co phases and along with the high surface area and pore diameter plays the key role for the obtained high catalytic activity in CoFe2O4 NPs. Moreover, the produced catalysts in this study exhibited good stability performance within maintained high catalytic activity for a period of at least 700 h of industrial-relevant FTS conditions.

Dimethyl Ether Conversion to Light Olefins on Zeolite Catalysts: Effect of MFI-Type Zeolite Nature and SiO2/Al2O3 Molar Ratio on Catalyst Efficiency

The physicochemical and catalytic properties of magnesium-containing zeolite catalysts based on MFI-type zeolites (ZSM-5 and CBV) were compared. The presence of larger mesopores volume in MgCBV was found to decrease selectivity towards light olefins. In order to improve the catalytic properties of MgCBV, the effect of SiO2/Al2O3 molar ratio of CBV (SiO2/Al2O3 = 30, 55, 80 and 300) on its physicochemical and catalytic properties in the reaction of the dimethyl ether (DME) into light olefins was studied. Increasing SiO2/Al2O3 molar ratio from 30 to 80, was shown not change practically the DME conversion and olefin selectivity, but under a SiO2/Al2O3 molar ratio of 300, DME conversion significantly reduces, olefin selectivity increases, while the ethylene/propylene ratio decreases twice. By changing residence time, DME conversion increases under high total light olefins selectivity, while the ethylene/propylene ratio raises with increasing residence time.

Direct CO2 hydrogenation to light olefins by suppressing CO by-product formation

Abstract We evaluate the direct CO2 conversion to light olefins reaction via a hybrid catalyst of In2O3/ZrO2 metallic oxide and zeolite SAPO34 components. On this catalyst, it can realize producing high light olefins selectivity of 77.59% via a direct tandem catalysis process, that is, the formed methanol on the oxygen vacancies surface of In2O3/ZrO2 in the first step will continue passing through the SAPO34 zeolite channel, where it is changed into light olefins simultaneously. Even there are many studies focused on this tandem catalysis reaction via bi-functional catalyst in recent years, however, to reduce the poisonous byproduct CO is still in a big challenge. In this reaction, large amounts of poisonous CO will be easily formed from reverse water gas shift reaction. Therefore, in our research, by optimizing the reaction, the catalyst can suppress the undesirable CO formation obviously. It shows good potential leading to scale-up cause of the outstanding reaction performance and its friendly-environment properties.

Numerical simulation on particle density and reaction pathways in methane needle-plane discharge plasma at atmospheric pressure

Methane needle-plane discharge has practical application prospect and scientific research significance since methane conversion heavy oil hydrogenation is formed by coupling methane needle-plane discharge with heavy oil hydrogenation, which can achieve high-efficient heavy oil hydrogenation and increase the yields of high value-added light olefins. In this paper, a two-dimensional fluid model is built up for numerically simulating the methane needle-plane discharge plasma at atmospheric pressure. Spatial and axial distributions of electric intensity, electron temperature and particle densities are obtained. Reaction yields are summarized and crucial pathways to produce various kinds of charged and neutral particles are found out. Simulation results indicate that axial evolutions of CH3+ and CH4+ densities, electric intensity and electron temperature are similar and closely related. The CH5+ and C2H5+ densities first increase and then decrease along the axial direction. The CH3 and H densities have nearly identical spatial and axial distributions. Particle density distributions of CH2, C2H4 and C2H5 are obviously different in the area near the cathode but comparatively resemblant in the positive column region. The CH3+ and CH4+ are produced by electron impact ionizations between electrons and CH4. The CH5+ and C2H5+ are respectively generated by molecular impact dissociations between CH3+ and CH4 and between CH4+ and CH4. Electron impact decomposition between electrons and CH4 is a dominated reaction to produce CH3, CH2, CH and H. The reactions between CH2 and CH4 and between electrons and C2H4 are critical pathways to produce C2H4 and C2H2, respectively. In addition, the yields of electron impact decomposition reactions between electrons and CH4 and reactions between CH2 and CH4 account for 52.15% and 47.85% of total yields of H2 respectively.

High efficient mesoporous HZSM-5 nanocatalyst development through desilication with mixed alkaline solution for methanol to olefin reaction

Methanol to olefin (MTO) process is a non-oil route for the light olefins production. We report the mesoporous and high siliceous HZSM-5 nanocatalyst development through the new desilication process including the mixed alkaline solution. The properties of nanocatalysts were characterized using TGA/DTA, XRD, ICP, FE-SEM, BET, FT-IR, and NH3-TPD techniques. FE-SEM images represent the spherical morphology of parent nanocatalyst including smooth surface. The XRD analysis confirms that applied desilication does not change the typical MFI-type structure of ZSM-5 nanocatalysts. The BET and NH3-TPD results show that mixed alkaline solution including 40 wt% TPAOH results in the best adjustment of textural (299.7 m2/g) and acidity (strong/weak ratio of 0.21) properties, respectively. The PHZ-NaTP0.4 nanocatalyst represents the highest methanol conversion (99.2%), propylene selectivity (48.3%), C3 =/C2 = molar ratio (7.4) as well as lowest selectivity to C1–C4 alkanes (4.6%) for long time on stream (170 h). The low selectivity of light alkanes (C1–C4) and high total light olefins (ca. 75%) confirm the stable performance of nanocatalyst. Consequently, the developed PHZ-NaTP0.4 nanocatalyst is a high efficient MTO catalyst and can be candidate for commercial scale up.

Selective Conversion of Glycerol into Propylene: Single-Step versus Tandem Process

Dehydration and catalytic cracking reactions can be combined to convert glycerol into light olefins using solid acid catalysts. The combination is suitable for a single-step process to convert glycerol into light olefins at high temperatures (26–36% selectivity at 873 K). However, large quantities of carbon oxides are produced (31–39% COx selectivity), and catalyst deactivation also occurs. High light olefin selectivity (62–65%) and a smaller quantity of carbon oxides (11–12% COx selectivity) can be obtained by using a tandem process involving the dehydration of glycerol and subsequent catalytic cracking of the dehydration products (mainly acetol and acrolein). Furthermore, the ratio of propylene to ethylene can be adjusted by changing the dehydration catalysts to favor the production of acetol or acrolein: Acetol forms propylene, and acrolein forms ethylene. To overcome the fast deactivation of acid catalysts in glycerol dehydration, the hydrogenolysis and catalytic cracking reactions can be synchronized...

Incorporation of mixed metals into SAPO-34 frameworks by the dry-gel conversion method using mixed templates: investigating catalysts characterisation and performance

ABSTRACTThe crystallisation of the MeAPSO-34 material was studied under dry-gel conversion conditions and using two and three templates. This study has been focused on the effect of the incorporation of a mixture of Ni and Mn into the SAPO-34 framework. The MeSAPO-34 samples were characterised by X-ray diffraction, energy-dispersive X-ray spectrometer, scanning electron microscope, temperature-programmed desorption and Brunner–Emmett–Teller. The influence of metal incorporation into the framework of SAPO-34 (MeAPSO-34) on methanol conversion was investigated in this study. The performances on methanol conversion for these catalysts were different according to the properties of metals incorporated into the SAPO-34 structure. The catalytic performance demonstrated high activity and light olefins selectivity for the prepared catalysts. Among the light olefin products, Mn and Ni incorporation is helpful for propylene generation, but samples with a mixture of Ni and Mn favour the ethylene production.