Highest Ethylene Yield Research Articles

Effect of different ligands on the preparation of Pt-xMn@HZSM-5 and their catalytic performance for iso-butane catalytic cracking

ZSM-5 has emerged as a promising catalyst for iso-butane catalytic cracking due to its unique pore structures and abundant acid sites. And the optimization of catalytic performance has attracted more and more attention. Herein, a series of Pt and Mn-embedded Pt-xMn@HZSM-5 catalysts with different Mn complexes were successfully synthesized via the one-pot hydrothermal method (x refers to the Mn/Pt ratio). The ligand effects of both ethylenediamine and ethylenediaminetetraacetic acid disodium salt on the nature of target samples in terms of crystallinity, porosity, morphology, metal state, and acidity, were investigated in detail. It has been demonstrated that ethylenediamine served as a ligand enabled Pt-xMn@HZSM-5 more metal nanoparticles and acid sites, thereby delivering improved catalytic performance and high yields of ethylene, propylene and BTX (benzene, toluene, and xylene) for iso-butane catalytic cracking.

Design of efficient supported Pd-Co catalysts for selective hydrogenation of acetylene

The research is devoted to the study of active component formation in the novel Pd-Co catalysts supported on carbon material Sibunit. It was shown that 0.5 %Pd–0.5 %Co/C samples exhibit high ethylene yield in the acetylene hydrogenation process due to the presence of fcc PdxCo(1-x) particles. According to in situ XRD-TPR analysis, solid solution formation begins during the reduction of samples in H2 at T ≥ 500 °C. Using the EXAFS, XRD and EDX it was established that H2-treatment at 500 °C leads to the formation of ∼Pd0.6Co0.4 particles and an increase in the reduction temperature to 600 and 700 °C is accompanied by the enrichment of the Pd-Co-phase with cobalt to ∼Pd0.5Co0.5 and ∼Pd0.45Co0.55 compositions, respectively. The ethylene yield on Pd-Co/C catalysts reduced at 500, 600 and 700 °C is 56, 66 and 68 %, respectively, which significantly exceeds the ethylene quantity obtained on monometallic Pd/C samples (∼52 %). It is assumed that the excellent selectivity of Pd-Co/C samples treated in H2 at 600 and 700 °C is due to an increase in the amount of palladium atoms surrounded by cobalt and a change in the palladium electronic state (XPS).

On the selective transformation of ethanol over Mg- and/or La-containing mixed oxides catalysts

MgO-La2O3 catalysts with different Mg/La molar ratio were synthesized by a precipitation method and a subsequent calcination and then characterized by x-ray diffraction, N2 adsorption-desorption isotherms (at −196 °C), CO2- and NH3-thermoprogrammed desorption and x-ray photoelectronic spectroscopy. The coexistence of acid and basic sites promoted the selective transformation of ethanol into valuable products. Thus, MgO catalyst promoted the Guerbet reaction obtaining n-butanol as product while the incorporation of La2O3 in the catalytic system improved the ethanol conversion notably, obtaining ethylene as the main product due to a dehydration reaction. The highest ethylene yield was obtained for the catalyst with a Mg/La molar ratio of 1.

Fine‐Tuning Texture of Highly Acidic HZSM‐5 Zeolite for Efficient Ethanol Dehydration

AbstractAchieving high and stable ethylene yield from (bio)ethanol dehydration over highly active acidic zeolite remains challenging due to undesired side‐reactions. To overcome this issue, the fine‐tuned textural property of the HZSM‐5 catalyst with a hierarchical structure is crucial to overcome diffusion restrictions and limit undesired side‐reactions. Herein, the texture of high acid catalysts obtained via hydrothermal synthesis was simply tuned in the presence of tetrabutylammonium hydroxide as a meso‐ and micropore directing agent and the controlled molar ratio of NaF‐to‐Al2O3. The hierarchically designed HZSM‐5 with the small nanosheet size of 6.5 nm exhibits a high external surface area and mesopores, largely enhancing the catalytic performance of ethanol dehydration up to 95 % ethylene yield as well as preventing the formation of heavy hydrocarbons. To gain insights into the mechanistic points of view, the in situ DRIFTS study revealed that ethylene could form through ethoxy‐mediated mechanism or decomposition of diethyl ether (DEE). The catalyst deactivation caused by polyaromatics obtained from side‐reactions is the reason for low ethanol conversion and high DEE selectivity. Reducing the crystal size of highly acidic zeolite to ultra‐thin nanosheet can shorten the residence time of ethanol, intermediates, and products in porous structures, substantially suppressing the transformation of coke precursors into heavy hydrocarbons to achieve high and stable ethylene yield.

Dimethyl Ether to Olefins on Hybrid Intergrowth Structure Zeolites

A series of catalysts based on hybrid intergrowth structure zeolites MFI-MEL, MFI-MTW, and MFI-MCM-41 are studied in the reaction of olefins synthesis from dimethyl ether at atmospheric pressure and a temperature of 340 °C. The total acidity of hybrid zeolite-based catalysts is shown to correlate with their activity. However, the use of zeolite with the structure MFI-MCM-41, which is characterized by a high content of medium acid sites, additionally catalyzes the methanol dehydration reaction, resulting in a decrease in the observed DME conversion. The obtained product distributions are brought into correlation with the texture of catalysts. It is shown that the use of hybrid zeolites does not change the mechanism of reaction, but the structural features of zeolites influence the priority of the competing MTO reactions: high ethylene yield is observed for catalysts with high micropore volume. The topology of the hybrid zeolite has been shown to influence the hydrogen transfer reaction rate, but not to change the isomerizing activity of the catalyst.

Effect of Ga substitution with Al in ZSM-5 zeolite in methanethiol-to-hydrocarbon conversion.

The catalytic properties of conventional H-[Al]-ZSM-5 and gallium-substituted H-[Ga]-ZSM-5 were evaluated in the conversion of methanethiol to ethylene (CH3SH → 1/2C2H4 + H2S). Dimethyl sulfide (DMS), aromatics, and CH4 were formed as byproducts on the H-[Al]-ZSM-5 catalyst. The introduction of Ga into the ZSM-5 structure provided a high ethylene yield with relatively high selectivity for olefins. Based on the temperature-programmed desorption of NH3 and pyridine adsorption on zeolites, the strength of acid sites was decreased by introducing Ga into the ZSM-5 structure. Undesirable reactions seemed less likely to occur at weakly acidic sites. The suppression of the formation of dimethyl sulfide (CH3SH → 1/2C2H6S + 1/2H2S) and the sequential reaction of ethylene to produce aromatics provided a high yield of ethylene over H-[Ga]-ZSM-5.

Effects of zeolite frameworks and hierarchical structures on catalytic bioethanol dehydration: In-situ DRIFTS and DFT studies

Herein, the combined in-situ diffuse reflectance infrared Fourier transform spectroscopy and density functional theory studies were employed to investigate the effects of different zeolite frameworks and hierarchical structures on catalytic bioethanol dehydration. The findings reveal that different zeolite frameworks enable the formation of distinct intermediates, hence promoting different mechanistic pathways. Interestingly, the FER is highly selective to ethylene and inhibits the formation of by-products thanks to the confined porous structure of the FER. Although the pristine small pore FER often suffers from fast catalyst deactivation, the incorporation of hierarchical structures in the FER framework can mitigate this significantly. Accordingly, the catalytic stability of the hierarchical FER was improved remarkably with a high ethylene yield (∼95%), whereas the pristine FER suffers from fast deactivation. Additionally, coke formation over the hierarchical FER catalyst was also reduced significantly compared to that of the pristine FER. Importantly, the in-situ DRIFTS studies reveal that the different reaction pathways over hierarchical and commercial FER have been observed in which the hierarchical one promotes the monomeric pathway due to the facile desorption of corresponding products and intermediates, whilst the pristine one promotes bioethanol conversion via both pathways of monomeric and dimeric pathways to produce ethylene and diethyl ether, respectively.

Crude oil conversion to chemicals over green synthesized ZSM-5 zeolite

The study reports the conversion of crude oil to basic chemicals over a template-free green synthesis of ZSM-5(40) zeolite using halloysite (HAL) and bolus alpha (BA) as silica and alumina precursors. The Z(40)HAL and Z(40)BA exhibited hierarchical pores with high surface area of 248 m2/g and 257 m2/g, respectively. The addition of soft template during the synthesis of Z(40)BA forms a Z(40)BAT zeolite with lower surface area. The synthesized zeolites were impregnated with 2wt%Mn and tested for the steam catalytic cracking of crude oil to light olefins and aromatics catalysts at 675 °C in a fixed-bed reactor. Maximum light olefins (C2=-C4=) yield (47 wt%) and total aromatics (14.7 wt%) were attained over 2Mn/Z(40)HAL catalyst. The conversion of crude oil (68.4%) is attributed to hierarchical pores and the presence of large weak and strong acid sites in the 2Mn/Z(40)HAL zeolite. Moreover, due to the high reaction temperature, some effects of thermal cracking such as protolytic cracking reactions with high ethylene yield (22%) were introduced. The addition of 1% phosphorus and 1%Mn to Z(40)HAL resulted in lower catalytic cracking activity. Similarly, the 2Mn/Z(40)BAT performed slightly lower than the template-free 2Mn/Z(40)BA additive. The experimental results demonstrate the technical feasibility of template-free green synthesis of ZSM-5 zeolite in the conversion of crude oil to basic chemicals.

Achieving high ethylene yield in non-oxidative ethane dehydrogenation

Steam cracking of ethane, a non-catalytic thermochemical process, remains the dominant means of ethylene production. The severe reaction conditions and energy expenditure involved in this process incentivize the search for alternative reaction pathways and reactor designs which maximize ethylene yield while minimizing cost and energy input. Herein, we report a comparison of catalytic and non-catalytic non-oxidative dehydrogenation of ethane. We achieve ethylene yields as high as 67 % with an open tube quartz reactor without the use of a catalyst at residence times ∼4 s. The open tube reactor design promotes simplicity, low cost, and negligible coke formation. Pristine quartz tubes were most effective, since coke formation was detected when defects were introduced by scratching the surface of the quartz. Surprisingly, the addition of solids to the quartz tube, such as quartz sand, alumina powder, or even Pt-based intermetallic catalysts, led to lower ethylene yield. Pt alloy catalysts are effective at lower temperatures, such as at 575 °C, but conversion is limited due to thermodynamic constraints. When operated at industrially relevant temperatures, such as 700 °C and above, these catalysts were not stable in our tests, causing ethylene yield to drop below that of the open tube. These results suggest that future research on non-oxidative dehydrogenation should be directed at optimizing reactor designs to improve the conversion of ethane to ethylene, since this approach shows promise for decentralized production of ethylene from natural gas deposits.

Технологии Изомалк-3 и Изомалк-3R для получения индивидуальных лёгких парафиновых углеводородов как сырья нефтехимических производств

The article discusses the new environmentally friendly catalytic technologies for processing butane cut, developed by SIE Neftehim LLC, giving wide opportunities for involving LPG in production of commercial value-added products. Development of petrochemical industry has created a demand for technologies and catalysts that enhance the economic efficiency of petrochemical products’ manufacturing and expand the feed base of petrochemical facilities without involving primary processing feeds. As the environmentally safe and economically effective solution, SIE Neftehim, LLC offers Isomalk-3 technology to produce maximum amount of isobutane, and Isomalk-3R technology to produce maximum amount of n-butane from isobutane cut. Application of Isomalk-3R technology expands the feed base for ethylene production due to isomerization of isobutane by-product to n-butane. N-butane is a valuable feed for pyrolysis units, providing high yields of ethylene, propylene, and n-butene used for polymer production. In turn, obtaining additional amounts of isobutane is possible due to application of n-butane to isobutane catalytic isomerization technology Isomalk-3. Isobutane cut produced in Isomalk-3 technology is notable for its high purity: the isobutane content may exceed 99 wt.%, it has no sulfur, nitrogen, chlorine, and oxygen impurities. Isobutane is in demand as the feed for production of alkylate, butyl rubber, oxygenates (MTBE and ETBE), isooctane. Isomalk-3 and Isomalk-3R processes do not require injection of chlorinating reagents, and the highly active catalytic system is resistant to poisons and impurities. Isomalk-3 and Isomalk-3R process designs are very similar, which allows integrating two units into one for alternate production of n-butane and isobutane.

Electrochemistry Enhanced Activation of Ethane for Co-Production of Ethylene and Hydrogen with Low-Thermal-Budget and Low-CO2-Emission

The shale gas revolution and rapidly increasing demand for hydrogen (for upgrading lower-quality oils and automotive industry), have spurred the development of more energy-efficient and cost-effective approaches to convert natural gas/natural gas liquids into high value-added fuels and chemicals. Ethylene, one of the largest building blocks in petrochemical industry, is mainly manufactured from high temperature steam cracking of ethane or naphtha. This method is energy intensive and represents the single most energy consuming process in the chemical industry. To fully exploit the potential of ethane as feedstock, we demonstrated electrochemistry enhanced co-production of ethylene and hydrogen through non-oxidative dehydrogenation of ethane at temperatures below 600oC with close to theoretical ethane conversion rate and high ethylene yield. Significant reduction in energy consumption and CO2 emission, compared to the commercial ethane steam cracking process was achieved. The remarkable performance is enabled by advanced fabrication of solid oxide proton conducting electrochemical membrane reactors incorporated with highly selective electrocatalysts as well as comprehensive operation optimization.

Stacked Additively Manufactured Electrochemical Cell for Reduction of Carbon Dioxide to Ethylene

An additively-manufactured two-cell stack is presented for the reduction of carbon dioxide to ethylene, forming part of a Horizon 2020 funded project, CO2EXIDE, which aims to recycle carbon dioxide in order to reduce greenhouse gas emissions1. In this work we present a new compact flow field design, which allows for an easily expandable cell stack through the manufacture of additional identical bi-polar flow fields2. The flow fields are manufactured from 316L stainless steel using the 3D printing technique – Direct Metal Laser Sintering (DMLS). This allows them to simultaneously act as the flow fields and current collectors. The DMLS technology enables complex internal pipework, shown in figure 1, which allows a compact cell with no external pipework. Our cell design is built around a membrane electrode assembly (MEA) (see figure 2), where CO2 is reduced at the cathode and water is oxidised at the anode3. The cathode is made from a copper nanoparticle catalyst, which is deposited onto a carbon gas diffusion layer. A nickel mesh is used as a catalyst for the anodic reaction. The flow fields were designed and optimised using the ANSYS Fluent 19.1 software in order to maximise residence time within the cell and ensure a similar pressure drop on each side of the MEA, which are essential to provide high reaction selectivity and to avoid pressure driven fluid transport across the proton exchange membrane respectively. Designing the flow field in this way allowed us to optimise our cell for both high ethylene yield and a long working life time (see figure 3 for the flow field pattern). The finished assembly (see figure 4) was analysed for its ability to selectively reduce CO2 to ethylene. CO2 was flowed over the cathode at varying flow rates, and the outflow gas was collected for ex situ analysis by gas chromatography. This design is promising for the future development of CO2 as a carbon source for ethylene, as the stackable design makes this assembly more easily scalable for large scale operations. [1] CO2EXIDE, “CO2EXIDE - CO2-based electrosynthesis of ethylene oxide,” 2018. [Online]. Available: http://www.co2exide.eu/. [Accessed 12 March 2019]. [2] O'Neil, Glen D.; Ahmed, Shakir; Halloran, Kevin; Janusz, Jordyn N.; Rodriguez, Alexandra; Terrero Rodriguez, Irina M. Single-step fabrication of electrochemical flow cells utilizing multi-material 3D printing. Electrochemistry Communications 99 (2019) 56-60. [3] DeWulf, D.W.; Jin, T.; Bard, A.J. Electrochemical and Surface Studies of Carbon Dioxide Reduction to Methane and Ethylene at Copper Electrodes in Aqueous Solutions. Journal of the Electrochemical Society. 136(6) (1989) 1686-1691. Figure 1

Investigation of the Selective Production of Ethylene from Propylene Over Small-Pore Zeolites.

The selective production of ethylene from the direct conversion of propylene (propylene-to-ethylene, PTE) was examined for the first time using various types of 8-membered ring (8-MR) zeolite materials with different pore structures. Among these 8-MR zeolites, SSZ-13 zeolite with a threedimensional chabazite structure exhibited the highest ethylene yield. To increase the ethylene selectivity further, the PTE reactions were conducted over SSZ-13 zeolite external surface modifications with silylation or phosphorus. The external surface modifications enhanced the ethylene selectivity due to the passivation of external acid sites. The surface-modified SSZ-13 catalyst exhibited the highest selectivity to ethylene, at more than 90% at 450 °C, a WHSV of 0.33 h-1, and a propylene particle pressure of 0.1 MPa.

Potential Production of Olefins in Pyrolysis of Algerian Gas Condensate Compounded with Ethane

The present work aims to investigate the possibility of substituting ethane, usually used as pyrolysis feedstock, by the Algerian gas condensate compounded with ethane. Several experiments have been setup using different percentage dilutions (5, 10, and 20%) of Algerian gas condensate and its fractions (light, medium and heavy) compounded with ethane. The impacts of temperature, steam flow and flows of material on the yield and composition of pyrolysis products have also been investigated. High yields of ethylene (19 to 36%) and propylene (9 to 20%) were obtained in the pyrogas. The present study demonstrates the potential of the Algerian gas condensate product which can be valorized and used to enhance the yields of ethylene and propylene used in the production process of polyethylene and polypropylene.

Mathematical Modeling of the Dehydrating Ethanol to Ethylene Process in a Multitubular Reactor on a Ring-Shaped Alumina Catalyst

The process of dehydrating ethanol to ethylene by varying geometrical dimensions of a ring-shaped alumina catalyst is studied using a mathematical 2D model of a multitubular reactor. The set of ring sizes determines equivalent grain size Req, on which catalyst’s effectiveness factor η depends in turn. A procedure is proposed for assigning grains with different geometric dimensions to four structural groups, depending on the technique used to synthesize samples with the same equivalent size Req. Based on this approach, a system of criteria is developed for selecting catalyst grains with the best characteristics for given conditions. The geometric sizes of grains and other parameters that ensure the highest ethylene yield at the lowest values of the pressure drop and the residence time are determined.

Catalytic Ethylene Oligomerization over Ni/Al-HMS: A Key Step in Conversion of Bio-Ethanol to Higher Olefins

Al-modified hexagonal mesoporous silica (HMS) materials were synthesized using dodecylamine as a template according to the methods reported in the literature. FT-IR spectra proved that Al3+ ions entered in the HMS framework in Al-HMS (prepared by sol-gel reaction) but Al3+ ions existed in the extra-framework in Al/HMS (prepared by post-modification). NH3-TPD indicated that either Al-HMS or Al/HMS had solid acid sites on the surface, and the acidic strength of Al/HMS was stronger than that of Al-HMS. For ethylene oligomerization at 200 °C under 1 MPa, Ni/Al-HMS showed an ethylene conversion of 96.3%, which was much higher than that over Ni/Al/HMS (45.6%). The selectivity for C4H8, C6H12, C8H16, and C8+ was 37.7%, 24.5%, 24.0%, and 9.1% for ethylene oligomerization over Ni/Al-HMS, respectively. Ni/Al-MCM-41, which has been reported as an effective catalyst for ethylene oligomerization in the literature, showed a high ethylene conversion (95.2%) similar to that of Ni/Al-HMS in this study. However, the selectivity for C8H16 over Ni/Al-MCM-41 (16.3%) was lower than that over Ni/Al-HMS (24.0%) in the ethylene oligomerization. For ethanol dehydration at 300 °C under 1 MPa, a commercial H-ZSM-5 catalyst showed a high ethylene yield (91.2%) after reaction for 24 h using a feed containing 90 wt.% ethanol and 10 wt.% water. In this study, a two-step process containing two fixed-bed reactors and one cold trap was designed to achieve the direct synthesis of higher olefins from bio-ethanol. The cold trap was used to collect the water formed from ethanol dehydration. By using H-ZSM-5 as a catalyst for ethanol dehydration in the first reactor and using Ni/Al-HMS as a catalyst for ethylene oligomerization in the second reactor, higher olefins were continuously formed by feeding a mixture containing 90 wt.% ethanol and 10 wt.% water. The yields of higher olefins did not decrease after reaction for 8 h in the two-step reaction system.

Combining CO2 Reduction with Ethane Oxidative Dehydrogenation by Oxygen-Modification of Molybdenum Carbide

The surface properties that determine the selectivity of Mo2C catalysts in ethane oxidative dehydrogenation with CO2 as a soft oxidant were investigated using a combination of pulse experiments and in-situ spectroscopic methods. Oxygen modification was discovered to be crucial for inhibiting the cleavage of the C–C bond in ethane and enhancing the production of ethylene. The addition of the Fe promoter accelerated the formation of surface oxygen species and stabilized them from reduction by ethane, leading to a shorter induction period, higher ethylene yield, and improved stability.

Investigation of lanthanum and Si/Al ratio effect on the HZSM-5 catalyst efficiency for production of Olefin from Methanol

ABSTRACTThe effect of lanthanum and Si/Al ratio on catalytic performance of HZSM-5 in methanol to olefin process is investigated in this paper. The catalyst with bases of HZSM-5 is modified using the lanthanum by a wet impregnation producer. The Box-Behnken method, experimental design is used to evaluate effects of lanthanum parameters, Si/Al ratio, temperature and the effect of the interaction between them in methanol to olefin process for production of ethylene and propylene. Finally, the obtained results show the highest yield of ethylene is achieved for high load lanthanum catalyst, low Si/Al ratio and high temperature.

Supported Ga-oxide Catalyst for Dehydrogenation of Ethane

We studied dehydrogenation catalysts to improve the performance of the ethane cracking tube. Ga, Ge, In, and Sn were studied as dehydrogenation catalysts. Catalytic activity tests showed that the Ga catalyst has the best performance among them. Although the Ga catalyst supported on α-Al2O3 calcined at 1323 K deactivated with time on stream, the Ga catalyst supported on γ-Al2O3 calcined at 1323 K showed high ethylene yield and stability. Analyses of BET, XRD, EDX, and XANES were conducted to elucidate the differences of their performances. Ga catalyst supported on γ-Al2O3 calcined at 1323 K showed high catalytic activity and stability because Ga was supported as a highly dispersed β-Ga2O3-like structure thanks to high specific surface area of the γ-Al2O3 support.

Kinetic Parameters for the Selective Hydrogenation of Acetylene on GaPd2 and GaPd.

Intermetallic GaPd2 is a highly selective and stable catalyst for the semi-hydrogenation of acetylene. Knowledge of the underlying reaction kinetics is essential to gain a deeper understanding of the selective hydrogenation on this catalytic material. To date, there has been no experimental kinetic data published for this reaction on a well-defined intermetallic catalyst possessing isolated active sites. Kinetic measurements are performed at 140-200 °C, revealing an apparent activation energy of 29(2) kJ mol-1 . GaPd2 is shown to be the first binary catalyst material, which shows a positive reaction order (0.89) with respect to acetylene at 200 °C. The influences on the extent of acetylene conversion, specific activity and selectivity to ethylene, ethane, and higher hydrocarbons are determined by a 24 factorial experiment following a design of experiments approach. Temperature and pressure have the strongest impact on these values. The results allow optimal operation for achieving high ethylene yields. A comparison of the reaction kinetics on GaPd2 with experimental results obtained for GaPd reveals different orders of reaction of H2 and C2 H2 on the two compounds.