Ethane Conversion Research Articles

Role of extra-framework aluminum species within MOR zeolites for syngas conversion via OXZEO catalysis

The location of aluminum within the framework or extra-framework of zeolites is a critical factor in determining its catalytic performance. Despite extensive research on the identification and formation mechanism of extra-framework aluminum (EFAl), its impact on catalytic performance requires further investigation. Herein, mordenite (MOR) zeolites with comparable acid density within the 8MR and 12MR channels but different EFAl contents were prepared, and their catalytic roles were examined in syngas conversion. Intelligent gravimetric analysis, model experiment of ethylene conversion and thermogravimetric analysis demonstrate that the existence of EFAl species can inhibit the secondary conversion of ethylene to long chain hydrocarbons (i.e., C5+) as well as the over-accumulation of carbonaceous species. However, excessive EFAl species lead to rapid deactivation due to restricted space and thus severe diffusion limitation. MOR zeolite with a moderate amount of EFAl species achieves a superior ethylene selectivity and exhibits an enhanced stability in syngas conversion when combined with ZnAlOx oxide. The insights gained in this work provide important guidance for the design of more efficient zeolite-based catalysts.

An Efficient Tri-Conductive Electrode for Ethane Direct Electrochemical Dehydrogenation on Proton Ceramic Electrolysis Cells.

The preparation of ethylene from ethane, a main component of shale gas, has become an important process of the petrochemical industry, using ethane steam cracking at high temperatures (>900 °C), which is a highly energy intensive industry. Here, direct dehydrogenation of ethane is engineered electrochemically to produce ethylene and hydrogen in a proton-conducting electrolysis cell, achieving over 50% ethane conversion and 90.42% ethylene selectivity at 700 °C. On the basis of constructing NiCu bimetallic alloy nano-catalyst on the surface of perovskite Sr3Fe2O7, Hafnium (Hf)element is doped in the bulk phase to improve proton conductivity, establish triple conductivity, and achieve efficient directional conversion of ethane. The carbon dioxide reduction reaction at the cathode is further coupled, resulting in a higher conversion of ethane on the anode side and the production of syngas on the cathode side. This electrochemical reaction process provides a choice for the clean production of high value-added small molecule chemical products.

Encapsulation of phosphine-palladium complex in USY zeolite for hydroesterification of ethylene to methyl propionate

With the development of green chemistry, researchers are eager to develop separable and recyclable catalyst for methyl propionate production through ethylene hydroesterification. Herein, a novel zeolite-encapsulated Pd complex was developed for ethylene hydroesterification with CO and methanol to methyl propionate. The introduced Pd component is coordinated with 1, 2-bis (di-tert-butyl phosphinomethyl) benzene ligand to form Pd complex, which is encapsulated in USY zeolite. This scheme solves the challenge of coupling phosphine-palladium complexes with acid promoters as heterogeneous catalysts. It was found that the increasing density of Brønsted acid sites on USY zeolite favors the ethylene hydroesterification. Furthermore, the influences of catalyst preparation and reaction conditions on the catalytic performance were assessed. As a result, the ethylene conversion could reach 99 % with MP selectivity of 100 % under the optimal condition. In addition, the catalytic heterogeneity and stability of zeolite-encapsulated Pd complex were investigated.

Synthesis of sustainable aviation fuels via (co–)oligomerization of light olefins

Within this study, the (co–)oligomerization of methanol-based olefins in the C2-4 range was investigated. The main objective was to increase the yield of oligomers with carbon chain lengths in the range of kerosene (C9-16). Commercially available mesoporous amorphous mixed silicon-aluminum oxides, optionally modified with nickel species, were applied as catalysts. Initially, single olefin feeds were employed, i.e. homo-oligomerization reactions of pure propylene and pure 1-butylene were studied at 120 °C and 32 bar olefin partial pressure, respectively. The co-oligomerization of olefin mixtures (C3+4 and C2+3+4), which can be obtained in Methanol-to-Olefins (MtO) processes, yields product mixtures with reduced selectivities to specific chain lengths. However, selectivities to kerosene-like olefins up to 85 % have been achieved and the main side product is gasoline. Investigations with varying reaction conditions reveal comparable effects as in the case of homo-oligomerization. The use of nickel-free catalysts resulted in the highest selectivities of kerosene-like olefins, but no ethylene was converted. The negative effects of nickel catalysts on fuel quality can be compensated by two consecutive catalyst beds, the first catalyst bed with a nickel-loaded silicon-aluminum oxide for ethylene conversion followed by a catalyst bed of neat silicon-aluminum oxide for the synthesis of highly branched, long chain oligomers. The reaction network for olefin oligomerization reactions is depicted, which can be simplified remarkably in the case of catalysts without nickel. A long-term experiment lasting for more than 200 h was conducted revealing a deactivation of the acid sites of the catalysts, but also the possibility of reactivation. Selectivity to kerosene-like olefins remained above 63 % and fuel characterization showed that the resulting kerosene fraction will be suitable for blending with conventional fuels.

Zr-modified γ-Al2O3 supported CrOx catalyst for CO2 assisted ethane dehydrogenation

γ-Al2O3 was modified with zirconia via the impregnation method to prepare a series of Cr/x-ZrO2/γ-Al2O3 catalysts for CO2 assisted ethane dehydrogenation to ethylene. The results revealed that the catalytic performance of the catalysts modified with ZrO2 is obviously improved, especially for the prepared catalyst containing 10 wt% zirconia. The Cr/10 %-ZrO2/γ-Al2O3 catalyst showed high activity at 650 ℃, with an ethane conversion of 51.3 % and ethylene yield of 37.8 %. Several techniques were applied to characterize the structural and chemical properties of the prepared catalysts. The results found that the modification of γ-Al2O3 surface by ZrO2 could enhance the metal-support interaction. Based on the results of characterization, we found that the dispersion of Cr species was promoted and the acidic sites were modified. Meanwhile, the modification caused a growth of the amount of Cr6+ species. Cr6+ species are the precursors of coordinatively unsaturated Cr3+ active sites, which are beneficial for the dehydrogenation of ethane. Besides, the role of CO2 during ethane dehydrogenation is also discussed. The result indicates that CO2 can eliminate the deposited coke and promote increased ethylene yield.

Pd Nanoparticles Decorated CeZrOx for Enhanced Photocatalytic Hydrogenation of Biomass‐Derived Compounds

AbstractThe photocatalytic conversion of biomass‐derived compounds into value‐added chemicals presents a promising protocol for the sustainable production of renewable chemicals. Our study explores the hydrogenation of biomass model compounds under visible light illumination. Zr was incorporated into the CeO2 framework, forming a CeZrOx(1:0.5) solid solution, confirmed by powder X‐ray diffraction (PXRD) and X‐ray photoelectron spectroscopy (XPS) analyses. The light uptake capacity of the CeZrOx solid solution was characterized using UV–visible spectroscopy. Additionally, the band structure of the CeZrOx solid solution was assessed using valance band X‐ray photoelectron spectroscopy (VB‐XPS) and Ultraviolet photoelectron spectroscopy (UPS) analysis, revealing a Z‐Scheme, which was further confirmed by various control experiments. Upon decorating the CeZrOx(1:0.5) solid solution with 1 wt% palladium (Pd), the resulting 1Pd/CeZrOx(1:0.5) composite exhibited improved charge separation and enhanced visible light absorption capacity. This composite achieved ∼99% conversion of furfural to tetrahydrofurfuryl alcohol under a 15 W blue LED illumination and 0.2 MPa hydrogen. Similarly, it demonstrated ∼99% conversion of benzyl phenyl ether (BPE) to toluene and phenol under a 10 W blue LED illumination. Our findings elucidate the active sites and demonstrate the recyclability of mixed metal oxides for selective furfural hydrogenation and BPE hydrogenolysis under visible light.

Rapid screening and experimental investigation of oxygen carriers for chemical looping oxidative dehydrogenation of ethane

Chemical looping oxidative dehydrogenation of ethane (CLODHE) is a promising alternative to ethylene production. The key to this technology is the development of oxygen carriers. In this paper, a novel rapid screening strategy for perovskite oxygen carriers, based on machine learning and thermodynamics, is proposed. Dozens of thermodynamically feasible oxygen carriers were screened for the CLODHE process and three of them were selected for further experimental verification. Among the selected oxygen carriers, LaCuO3 had the best performance. LaCuO3 achieved an ethane conversion of 51.3 % and an ethylene selectivity of 93.93 % over 10 cycles at 750 °C and 18,000 ml·h-1·g-1, respectively. XPS patterns showed that the composition and content of oxygen remained almost unaltered before and after the cycling, which may be the reason for its stability. The decreased in Cu3+ indicated it played a crucial role in oxidative dehydrogenation of ethane. SEM-EDS patterns showed that the oxygen carriers became agglomerated after cycling, leading to a slight reduction in reactivity. The proposed strategy is appropriate for binary to quaternary perovskites and can also be applied to other reactions, providing insights into material design and accelerating their development.

CO2 utilization and on-purpose ethylene production: A chemical looping approach

CO2-assisted ethane dehydrogenation (CO2-ODHE) is a promising carbon atom economy process for upgrading CO2 to CO in tandem with C2H6 to C2H4 conversion. Iron oxide-based materials are selective for on purpose ethylene production through CO2-ODHE. The feed admission mode was found to play an important role on catalytic performance. Alternating C2H6 (reduction step) and CO2 (oxidation step) feedstock to a fixed bed reactor (chemical looping concept, CO2-ODHE-CL) attained constant ethane and CO2 conversion per step at 600 °C, equal to ∼17.6 %, while C2H4 selectivity during the reduction step was ∼75 %. The lattice oxygen mobility is a descriptor for the materials used during the CO2-ODHE-CL, since low mobility resulted in an increased C-H bond scission selectivity, i.e., C2H4 production, during the reduction step. Temperature programmed 18O2 isotope exchange experiments, along with temperature programmed H2 – reduction, were employed to exemplify the latter statement, investigating the lattice oxygen reactivity of the examined materials and the mechanism through which the lattice oxygen is reacting. X-ray techniques (X-ray Diffraction, X-ray Raman Scattering Spectrometry, X-ray Absorption Spectrometry) along with structural modeling demonstrated that the formation of a spinel like arrangement between Mg and Fe, stabilized lattice oxygen and thus minimized the undesired C-C bond scission during the C2H6 step of CO2-ODHE-CL.

Interface engineering to construct heterostructured MoO3/SmMn2O5 for chemical looping oxidative dehydrogenation of ethane

Electronic structure and lattice oxygen in metal oxides play important roles in the chemical looping oxidative dehydrogenation of ethane. Herein, an interface strategy is proposed to tailor electronic structure and activate lattice oxygen of mullite SmMn2O5 via the interface fabrication with MoO3 for enhancing the reactivity of the sample. The optimized 2MoO3/SmMn2O5 oxygen carrier exhibited 50 % ethane conversion and 83.9 % ethylene selectivity higher than that of pure SmMn2O5 and pure MoO3. Density functional theory simulations and characterization results revealed that the interface of MoO3/SmMn2O5 regulated the d-band center, which tailored the adsorption of ethane. Besides, the interface of MoO3/SmMn2O5 also caused the charge transfer from Mn atoms in SmMn2O5 to O atoms in MoO3 and SmMn2O5, leading to a reduction of the Mn-O bond strength and an enhancement in the activity of the lattice oxygen and Oads. This study provides useful insights to regulate electronic structure and activate lattice oxygen of oxygen carrier through interfacial engineering for the practical application of ethane chemical looping oxidative dehydrogenation.

N2O Assisted Ethane Transformation into Ethylene Using NiO−CeO2−ZrO2 Catalysts

AbstractNiO−CeO2 and NiO−CeO2−ZrO2 catalysts have been synthesized, electrochemically characterized (Mott‐Schottky (MS) measurements and Electrochemical Impedance Spectroscopy), physicochemically characterized (by N2 adsorption, XRD, Transmission Electron Microscopy and XPS) and tested in the N2O assisted ethane oxydehydrogenation. The use of low Zr‐loadings (Zr/Ce=0.1 at. ratio) has led to the optimal results in the ethylene production, improving those obtained by the Zr‐free NiO−CeO2 catalyst. However, high Zr‐loadings have meant a decrease in the olefin production. The catalytic results obtained have been explained considering the amount of oxygen vacancies, the crystalline phases formed and, especially, the nature of the surface Ni species. Importantly, the use of N2O as an oxidizing agent leads to a remarkable improvement in the selectivity to the olefin compared to that obtained employing molecular O2. Then, for a given ethane conversion the selectivity to ethylene is ca. 15 points higher using N2O than using O2. Another additional positive aspect of this NiO−CeO2−ZrO2 catalyst is its high catalytic stability.

Cascade Conversion of CO2 to Ethylene Carbonate under Ambient Conditions.

Ethylene carbonate (EC) is the simplest cyclic carbonate with great industrial significance, most importantly as the vital electrolyte component for lithium-ion batteries. Its conventional synthesis generally involves the use of toxic precursors and requires elevated temperatures and pressures. Herein, we propose a cascade catalytic route for converting CO2 to EC under ambient conditions. Such a hybrid reaction scheme consists of the electrochemical reduction of CO2 to ethylene catalyzed by copper in a membrane electrode assembly reactor, the bromine-mediated conversion of ethylene to bromoethanol catalyzed by WO3 nanoarrays grown on carbon cloth, and the reaction between bromoethanol and CO2 to form EC. By separately optimizing individual catalytic steps and then integrating them together in series, we achieved the conversion of CO2 to EC at a good yield under room temperature and atmospheric pressure. Our study also represents the first demonstration about the successful synthesis of organic carbonates from CO2 as the exclusive carbon source.

Comparative Study Between Design and Parameter Adjustment for Profit Maximization of Low-Density Polyethylene (LDPE) Production in High-Pressure Tubular Reactor

Low density polyethylene (LDPE) market becomes increasingly competitive and profit margins are tightening, manufacturers must create solutions to optimize profit in LDPE high pressure tubular reactors. Thus, in this study, the optimization of LDPE was proposed and conducted by improving the design and parameter adjustment of the LDPE tubular reactor. A mathematical model was developed and validated with industrial data by using MATLAB R2021. Input parameter study was carried out to investigate the effect of initiator concentration (CI), monomer concentration (CM), and solvent concentration (CS) to the ethylene conversion rate, reaction temperature rate, and final product grade, respectively. The CM was identified as the most significant parameter to influence LDPE polymerization process. CM increment results in the highest reaction temperature peak, which was originating from 249.58 to 299.21oC. The highest MFI value was also obtained when the CM was increased from 0.01954 to 0.01979 mol/cm3. Then, a comparative study between design and parameter adjustment for profit maximization in LDPE High Pressure Tubular Reactor was conducted. With the profit of RM166.83 million/year, compared to RM106.83 million/year, double reaction zones demonstrates that it has much better ethylene conversion rate compared to single reaction zone with optimization.

Mechanism and Kinetics of Ethanol–Acetaldehyde Conversion to 1,3-Butadiene over Isolated Lewis Acid La Sites in Silanol Nests in Dealuminated Beta Zeolite

Mechanism and Kinetics of Ethanol–Acetaldehyde Conversion to 1,3-Butadiene over Isolated Lewis Acid La Sites in Silanol Nests in Dealuminated Beta Zeolite

Enhancement of ethylene selectivity in chemical looping oxidative dehydrogenation of ethane using manganese-based redox catalysts supported on HY zeolite

As the crucial role of zeolite catalysts becomes increasingly prominent in refining and petrochemical industries, this study introduces a novel application of xMn / HY catalysts in ethane catalytic dehydrogenation via Chemical Looping Oxidative Dehydrogenation (CL-ODH). The synergistic effect of manganese oxides on the HY framework and a moderate amount of acidic sites within the catalyst facilitates the cleavage of C-H bonds and the desorption of olefins, which are vital for advancing ethane CL-ODH. We identified the reasons for maintaining high ethylene selectivity using advanced characterization techniques such as XRD, SEM, TEM, BET, H2-TPR, NH3-TPD, and Py-IR. Notably, under optimized conditions at 700 °C with a gas time-space velocity (GHSV) of 1800 mL·h−1·g−1, the 3Mn/HY catalyst achieved approximately 97.1 % selectivity for ethylene and a 22.7 % conversion of ethane. These findings present a scalable route for ethylene production, showcasing significant industrial relevance by potentially reducing energy costs and improving yield.

Boron vs. aluminum in ZSM-5 zeolites: Solid-state NMR, acidity, and C1/C2 reactant conversion

Three zeolite catalysts with comparable amounts of aluminum and/or boron ([Al]ZSM-5, [B,Al]ZSM-5, and [B]ZSM-5) are herein synthesized. Water (H2O), ammonia (NH3), acetonitrile-d3 (ACN), and trimethylphosphine oxide (TMPO) are applied as probe molecules to investigate the acidity of the respective materials in combination with 11B, 27Al, and 29Si MAS NMR spectroscopy. Ammonia is not protonated to ammonium on Si(OH)B groups and only LAS-bound ammonia persists desorption. Thus, ammonia gives a realistic, quantitative picture of the present acid sites. ACN interacts only with Si(OH)Al as desired. The strong base TMPO results in a misleading, not quantifiable picture. Subsequent hydration is unsuited to distinguish BAS and LAS densities. The samples were catalytically tested in the conversion of methanol, ethanol, and ethylene. [B]ZSM-5 is unreactive in hydrocarbon formation due to absence of BAS, instead LAS are present. The mixed [B,Al]ZSM-5 shows a decreased lifetime in MTO conversion compared to the [Al]ZSM-5, due to LAS presence. A sometimes reported superior reactivity of [B,Al]ZSM-5 catalysts is thus explained primarily by an optimized BAS density.

Photo-enhanced selective conversion of ethane to ethene over single-site Mo-modified SAPO-34

Photo-enhanced selective conversion of ethane to ethene over single-site Mo-modified SAPO-34

Interfacially coupled Cu-cluster/GaN photocathode for efficient CO2 to ethylene conversion

Interfacially coupled Cu-cluster/GaN photocathode for efficient CO2 to ethylene conversion

Tailor-made the ultrathin nanosheet and acid site accessibility of mordenite zeolite for carbonylation of dimethyl ether

Precisely tailored nano-morphology and crystal growth endures mordenite (MOR) zeolites with reduced internal diffusion resistance, enabling greater accessibility of existing acid sites to further stimulate catalysis. Controllable synthesis nanosheet MOR zeolite thinner than 20 nm along at least one dimension is highly attractive but remains great challenge. Herein, c axis along the [001] direction shortened MOR nanosheets with a thickness of 10–20 nm was synthesized. As expected, the mass transfer performance over the nanosheet sample is significantly improved by 2.5 times compared with the conventional nano-morphology. Furthermore, more Brønsted acid sites (BAS) can be induced into 8-membered ring (8-MR) pores in the nanosheet MOR zeolite. The conversion of dimethyl ether (DME) to methyl acetate over the ultrathin MOR zeolite is increased from 17.4 % to 71.7 % compared to that of the conventional nanoparticle. The DME conversion was stable at 70.0 % after reaction 80 h, when the acid sites located in 12-membered ring pores was poisoned by the pyridine molecule. Unexpectedly, we discovered that the desorption behavior of pyridine is also influenced by the accessibility of acid site, not only by the amount of BAS in 8-MR. The unique nanosheet structure with short c axis reduces the spatial stability of pyridine adsorbed on BAS in the 8-MR side pocket and the BAS in the 8-MR side pocket can be recovered at lower temperatures. Herein, a new insight into of DME carbonylation catalyzed by ultrathin nanosheet of MOR zeolite is revealed.

Stabilized Cu0 -Cu1+ dual sites in a cyanamide framework for selective CO2 electroreduction to ethylene

Electrochemical reduction of carbon dioxide to produce high-value ethylene is often limited by poor selectivity and yield of multi-carbon products. To address this, we propose a cyanamide-coordinated isolated copper framework with both metallic copper (Cu0) and charged copper (Cu1+) sites as an efficient electrocatalyst for the reduction of carbon dioxide to ethylene. Our operando electrochemical characterizations and theoretical calculations reveal that copper atoms in the Cuδ+NCN complex enhance carbon dioxide activation by improving surface carbon monoxide adsorption, while delocalized electrons around copper sites facilitate carbon-carbon coupling by reducing the Gibbs free energy for *CHC formation. This leads to high selectivity for ethylene production. The Cuδ+NCN catalyst achieves 77.7% selectivity for carbon dioxide to ethylene conversion at a partial current density of 400 milliamperes per square centimeter and demonstrates long-term stability over 80 hours in membrane electrode assembly-based electrolysers. This study provides a strategic approach for designing catalysts for the electrosynthesis of value-added chemicals from carbon dioxide.

Bimetallic Catalysts in Acetylene Semi‐Hydrogenation: Conceptual Advances and Challenges

AbstractThe hydrogenation of acetylene to ethylene is of great industrial interest. Achieving both high selectivity and high conversion of acetylene to ethylene via semi‐hydrogenation is quite challenging. Bimetallic catalysts offer opportunities to selectively control reaction pathways by altering the electronic and geometric properties of active sites on the catalyst surface. Recent advancements in the synthesis of bimetallic catalysts enabled the creation of random alloys, intermetallics, segregated structures, or single‐site alloys with precision. These catalysts could be tailored for semi‐hydrogenation of acetylene by tuning the features including adsorption energy, active site isolation, and the d‐band center. Modern machine learning tools are also helpful for catalyst design. In this article, an overview of the conceptual advances in the design aspects of bimetallic catalysts, advances and challenges involved in the acetylene semi‐hydrogenation, has been presented.