Butene Selectivity Research Articles

Electronic effect in bromide-modified noble metal catalysts promotes highly stable and selective hydrogenation

Halides with strong affiliation to metals are traditionally viewed as positions in heterogeneous catalysis. This study introduces a method to enhance the selective hydrogenation performance of noble metal nanoparticle catalysts (Pd, Pt, and Rh hosted on N-doped carbon, SiO2, and Al2O3) by gas-phase bromination with 1-bromooctane. Brominated Pd catalysts, particularly those supported on N-doped carbon, show significant improvements in total butene selectivity and stability in butadiene hydrogenation reactions, displaying >97.5 % selectivity to total butenes at complete conversion with 50 h stable performance even at excessive H2 (H2:butadiene = 50) and a high temperature of 473 K. Comprehensive characterizations coupled with density functional theory calculations reveal that bromide species enhance selective hydrogenation by preferentially adsorbing at stepped Pd sites, altering reaction kinetics and preventing over-hydrogenation. Bromination influences reactant and intermediate adsorption, leading to increased competitive adsorption compared to pristine catalysts. Chemisorption studies on butadiene and 1-butene support altered kinetic behaviors post-bromination. X-ray photoelectron spectroscopy analysis demonstrate an increase in surface Pdδ+ species, owing to the electron-pulling character of nearby adsorbed bromide. In situ diffuse reflection infrared Fourier transform spectroscopy with CO probe molecules confirms Br species adsorption at unsaturated Pd sites. Overall, the study provides an effective approach to tuning the electronic properties of metal catalysts and highlights the positive impact of bromination on improving the hydrogenation performance.

Active site requirements for bio-alcohol dehydration: Effect of chemical structure and site proximity

Synthesis-structure-activity relations are reported, describing how interzeolite conversion (IZC) allows synthesis of ZSM-5 (MFI framework) with fixed physicochemical properties, except the variable local acid site (Al) arrangement, by variation of the synthesis time. Local confinement and acidity effects are probed by applying both H-ZSM-5 and Na-ZSM-5 samples in alcohol dehydration. Pyridine and divalent cobalt ion probing are used to quantify the amount of accessible acid sites and of Al in close proximity. Al in close proximity shows a strong influence on n-butanol dehydration turnover rates. The turnover rates are also strongly dependent on local confinement: in Na-form, ZSM-5 synthesized with more Al present as isolated species is a factor of 3–7 times more active than Na-ZSM-5 with fewer isolated Al. However if the zeolites are in proton form, ZSM-5 with more proximate sites show a higher activity compared to ZSM-5 with more isolated sites. Linear butene selectivity increases in Na-ZSM-5 compared to H-ZSM-5, caused by a suppressed dibutyl ether formation. The selectivity towards 1-butene is enhanced to a greater extent on proximate sites, likely due to a local/steric constraint at the active site. Decomposition of DBE over Na-ZSM-5 is more active compared to n-butanol dehydration, independent of acid site proximity. Also for 2-propanol dehydration, Na-ZSM-5 is less active than H-ZSM-5, yet the activity difference is attenuated compared to n-butanol dehydration. Essentially, due to the intrinsic higher reactivity of 2-propanol, the acid site requirement is less stringent. These findings highlight the importance of local confinement and Al proximity in acid-catalyzed conversion of oxygenated compounds.

Catalytic Synthesis of Butene-1 and Hexene-1 in the Homogeneous Oligomerization of Ethylene in the Presence of Nickel Complexes Based on N-Heteroaryl-Substituted α-Diphenylphosphinoglycines

It has been experimentally shown that N-heteroaryl-substituted α-diphenylphosphinoglycines N-(pyrazin-2-yl)-α-diphenylphosphinoglycine, N-(pyridin-2-yl)-α-diphenylphosphinoglycine and N-(pyrimidin-2-yl)-α-diphenylphosphinoglycine obtained by the reaction of three-component condensation of diphenylphosphine, the corresponding primary amine and glyoxylic acid monohydrate are capable in combination with Ni(COD)₂, where COD is cyclooctadiene-1,5, to form active forms of catalysts for selective homogeneous dimerization and trimerization of ethylene with the formation of butene-1 and hexene-1 as the main products. It has been established that the obtained organo-nickel catalytic systems provide a yield of short-chain (C₄–C₆) olefins at the level of 90% with a selectivity for linear α-olefins of 97%. The study of the influence of temperature on the process of homogeneous ethylene oligomerization using the obtained compounds made it possible to establish that the optimal temperature for ethylene oligomerization, providing the highest selectivity to butene-1 and hexene-1, is 80–105°C at the optimum pressure of ethylene is 20–35 atm. Under these conditions, the selectivity for butenes is 71.4–72.6% (selectivity for butene-1 – 69.3–71.1%), for hexenes 20.6–21.2% (selectivity for hexene-1 – 19.2–19.5%), and the optimal duration of the oligomerization process at a temperature 105°C is 1.5 h, which provides the rate of formation of butene-1 equal to 168.1 golig gNi⁻¹h⁻¹) and the rate of formation of hexene-1 – 47.3 golig gNi⁻¹h⁻¹).

Monodentate Phosphinoamine Nickel Complex Supported on a Metal-Organic Framework for High-Performance Ethylene Dimerization.

Ethylene dimerization is an efficient industrial chemical process to produce 1-butene, with demanding selectivity and activity requirements on new catalytic systems. Herein, a series of monodentate phosphinoamine-nickel complexes immobilized on UiO-66 are described for ethylene dimerization. These catalysts display extensive molecular tunability of the ligand similar to organometallic catalysis, while maintaining the high stability attributed to the metal-organic framework (MOF)scaffold. The highly flexible postsynthetic modification method enables this study to prepare MOFs functionalized with five different substituted phosphines and 3 N-containing ligands and identify the optimal catalyst UiO-66-L5-NiCl2 with isopropyl substituted nickel mono-phosphinoamine complex. This catalyst shows a remarkable activity and selectivity with a TOF of 29000 (molethyl/molNi/h) and 99% selectivity for 1-butene under ethylene pressure of 15bar. The catalyst is also applicable for continuous production in the packed column micro-reactor with a TON of 72000 (molethyl/molNi). The mechanistic insight for the ethylene oligomerization has been examined by density functional theory (DFT) calculations. The calculated energy profiles for homogeneous complexes and truncated MOF models reveal varying rate-determining step as β-hydrogen elimination and migratory insertion, respectively. The activation barrier of UiO-66-L5-NiCl2 is lower than other systems, possibly due to the restriction effect caused by clusters and ligands. A comprehensive analysis of the structural parameters of catalysts shows that the cone angle as steric descriptor and butene desorption energy as thermodynamic descriptor can be applied to estimate the reactivity turnover frequency (TOF) with the optimum for UiO-66-L5-NiCl2. This work represents the systematic optimization of ligand effect through combination of experimental and theoretical data and presents a proof-of-concept for ethylene dimerization catalyst through simple heterogenization of organometallic catalyst on MOF.

MOF-Derived ZrO2-Supported Bimetallic Pd-Ni Catalyst for Selective Hydrogenation of 1,3-Butadiene.

A series of MOF-derived ZrO2-supported Pd-Ni bimetallic catalysts (PdNi/UiO-67-CTAB(n)-A500) were prepared by co-impregnation and pyrolysis at 500 °C under air atmosphere using UiO-67-CTAB(n) (CTAB: cetyltrimethylammonium bromide; n: the concentration of CTAB; n = 0, 3, 8, 13, 18) as a sacrificial template. The catalytic activity of PdNi/UiO-66-CTAB(n)-A500 in 1,3-butadiene hydrogenation was found to be dependent on the crystal morphology of the UiO-67 template. The highest activity was observed over the PdNi/UiO-67-CTAB(3)-A500 catalyst which was synthesized using UiO-67-CTAB(3) with uniform octahedral morphology as the template for the 1,3-butadiene selective hydrogenation. The 1,3-butadiene conversion and total butene selectivity were 98.4% and 44.8% at 40 °C within 1 h for the PdNi/UiO-67-CTAB(3)-A500 catalyst, respectively. The catalyst of PdNi/UiO-67-CTAB(3)-A500 can be regenerated in flowing N2 at 200 °C. Carbon deposited on the surface of the catalyst was the main reason for its deactivation. This work is valuable for the high-efficiency bimetallic catalyst's development on the selective hydrogenation of 1,3-butadiene.

Sulfonate Functional Ultramicroporous Materials with Suitable Pore Size and Layer-Stacked Structure for C4 Olefins Purification.

Selective recognition of 1,3-butadiene from complex olefin isomers is vital for 1,3-butadiene purification, but the lack of porous materials with suitable pore structures results in poor selectivity and low capacity in C4 olefin separation. Herein, two sulfonate-functionalized organic frameworks, ZU-601 and ZU-602, are designed and show impressive separation performance toward C4 olefins. Benefiting from the suitable aperture size caused by the flexibility of coordinated organic ligand, ZU-601, ZU-602 that are pillared with different sulfonate anions could discriminate C4 olefin isomers with high uptake ratio: 1,3-butadiene/1-butene (207), 1,3-butadiene/trans-2-butene (10.1). Meanwhile, their layer-stacked structure enables the utilization of both intra- and interlayer space, enhancing the accommodation of guest molecules. ZU-601 exhibits record high 1,3-butadiene adsorption capacity of 2.90 mmol g-1 (0.5 bar, 298 K) among the reported flexible porous materials with high 1,3-butadiene/1-butene selectivity. The breakthrough experiments confirm their superior separation ability even for all five C4 olefin isomers, and the molecular-level structural change is well elucidated via powder, crystal analysis, and simulation studies. The work provides ideas toward advanced materials design with simultaneous high separation capacity and high separation selectivity for challenging separations.

Modulation of Al Distribution in High-Silica ZSM-5 Zeolites for Enhancing Catalytic Performance.

The spatial distribution of framework Al (AlF) has been one of the important factors that affect the catalytic properties of zeolites in diverse chemical reactions; however, the synthesis of high-silica zeolites with special AlF distribution remains a challenge. In this study, we successfully synthesized high-silica ZSM-5 zeolites with a unique AlF distribution by employing pentaerythritol (PET) as an additive in the presence of a few tetrapropylammonium hydroxide (TPAOH). The results demonstrated that the introduction of PET led to a higher proportion of Al atoms located at the sinusoidal and/or straight channels. It was observed that the addition of PET prevented the interaction between TPA+ and tetrahedral [AlO4]- during the crystallization process, resulting in enhanced availability of TPA species in the form of ion-paired TPA+. This effect leads to AlF atoms dominantly distributed away from the intersection and located in narrow channels, where acidic sites more effectively inhibit hydrogen transfer and coke formation. In the reaction of dimethyl ether (DME) to olefins, the catalyst with a unique Al distribution exhibited a significant prolonged catalytic lifetime, surpassing traditional TPA-ZSM-5 by more than 2-fold and maintaining DME conversion above 90% for a maximum of 148 h. The results of multiple pulse experiments also showed that these PET-assisted ZSM-5 zeolites significantly enhanced the selectivity of propene and butene. This approach provides an effective strategy to regulate AlF distribution in high-silica ZSM-5 catalysts with the assistance of neutral alcohol. It holds great potential for application in the synthesis of other high-silica zeolites, thereby enriching the diversity of zeolite catalysis.

Cr-catalysed ethylene dimerization in an ionic liquid-organic solvent biphasic system with perfect 1-butene selectivity.

Cr-catalyzed ionic liquid-organic biphasic ethylene dimerization was realized with 100% 1-butene selectivity. The perfect α-olefin selectivity can be rationalized in terms of the poor solubility of the oligomerized long-chain olefins in ionic liquids, and enables the establishment of a dimerization process without any complicated and energy-intensive catalyst and byproduct separation processes.

Butane Dehydrogenation: Thermodynamic Modeling and Performance Analysis of Selected Process Simulators

The critical role of process simulation in modern chemical engineering cannot be overstated, with its capacity to facilitate process scale-up, assess alternative designs, and comprehend plant efficiency. This research delves into the performance of three software programs, Cape-Open to Cape-Open (CC), DWSim, and Aspen HYSYS (AH), in modeling butane dehydrogenation. The focus is on their ability to accurately model thermodynamic properties and chemical reaction dynamics. Butane dehydrogenation was evaluated with specific thermodynamic parameters using a Gibbs reactor model with Gibbs minimization. The Soave Redlich-Kwong thermodynamic model was employed to investigate the impact of temperature of 700 °C and pressures of 0.1 MPa and 1.0 MPa on the yield and selectivity of butadiene and butene. The CC and AH simulation results closely agreed with the available experimental data. The consistency of freeware simulators with a commercial simulator was also assessed, with AH serving as the reference standard. It was revealed that CC demonstrates higher consistency with it than DWSim under both low- and high-pressure conditions. This study confirms that CC is a reliable process simulator suitable for use in resource-constrained settings where expensive commercial licenses are prohibitive.

Computer-aided ligand screening to develop polymer-free catalyst in Cr-catalyzed ethylene oligomerization

Preventing the formation of undesirable polymer in ethylene oligomerization is a major challenge since the presence of these insoluble materials can cause severe reactor fouling. Based on previous experimental data, the concomitant formation of these solid compounds can be divided in two types. Detailed discussion in combination with mathematical analysis revealed that the low-molecular weight waxes (low-Mw waxes) are most likely the tail products of the Schulz-Flory distribution while high-molecular weight polyethylene (high-Mw PE) may be catalyzed by multiple active sites independent from the oligomerization cycle. Controlling the Schulz-Flory coefficient (K value) to remain in a lower range is crucial in achieving plentiful C4–C8 components and inhibiting polymer formation at the same time. Attempting to predict the K value, the energetic disparities of key transition states which control 1-butene selectivity have been extracted as a chemical descriptor to establish a general model. Promising ligands derived from computer-aided screening are expected to avoid the inherent waxes formation. Plausible strategies for the elimination of external polymerization sites are also suggested. The combination of them may provide a chance to develop more polymer-free catalysts to meet the requirements of industrial manufacturing.

Promoting Syngas to Olefins with Isolated Internal Silanols-Enriched Al-IDM-1 Aluminosilicate Nanosheets.

Selective conversion of syngas to value-added olefins has attracted considerable research interest. Regulating product distribution remains challenging, such as achieving higher olefin selectivity, propylene/ethylene (P/E) and olefin/paraffin (O/P) ratios. A new pentasil zeolite Al-IDM-1 with recently approved -ION structure, composed of 17-membered-ring (MR) extra-large lobed pores and intersected 10-MR medium pores, shows a C2-6 = selectivity up to 85 % and a high O/P value of 14 in the conversion of syngas when being combined with Zna Alb Ox oxide. Moreover, for the high-silica Al-IDM-1 with Si/Al ratio of 400, the selectivity of propylene and butene accounts for 88 % in C2-4 = , resulting in high P/E (>4) and butene/ethylene (B/E >3) ratios. The high C3-4 = selectivity is contributed by two main reasons, that is, the relatively weak acidity of Al-IDM-1 zeolite enhances the olefin-based cycle revealed by the probe reactions of methanol-to-propylene (MTP) and 1-hexene cracking, and the rich isolated internal SiOH groups in Al-IDM-1 promote the desorption of C3-4 = , once they are formed inside zeolite pores.

Promoting Syngas to Olefins with Isolated Internal Silanols‐Enriched Al‐IDM‐1 Aluminosilicate Nanosheets

AbstractSelective conversion of syngas to value‐added olefins has attracted considerable research interest. Regulating product distribution remains challenging, such as achieving higher olefin selectivity, propylene/ethylene (P/E) and olefin/paraffin (O/P) ratios. A new pentasil zeolite Al‐IDM‐1 with recently approved −ION structure, composed of 17‐membered‐ring (MR) extra‐large lobed pores and intersected 10‐MR medium pores, shows a C2–6= selectivity up to 85 % and a high O/P value of 14 in the conversion of syngas when being combined with ZnaAlbOx oxide. Moreover, for the high‐silica Al‐IDM‐1 with Si/Al ratio of 400, the selectivity of propylene and butene accounts for 88 % in C2–4=, resulting in high P/E (>4) and butene/ethylene (B/E >3) ratios. The high C3–4= selectivity is contributed by two main reasons, that is, the relatively weak acidity of Al‐IDM‐1 zeolite enhances the olefin‐based cycle revealed by the probe reactions of methanol‐to‐propylene (MTP) and 1‐hexene cracking, and the rich isolated internal SiOH groups in Al‐IDM‐1 promote the desorption of C3–4=, once they are formed inside zeolite pores.

H2 -free Semi-hydrogenation of Butadiene by the Atomic Sieving Effect of Pd Membrane with Tree-like Pd Dendrites Array.

H2 -free semi-hydrogenation at room temperature shows great advantage for replacing the thermocatalytic process in industry owing to the high energy and resource saving, however, remains great challenges. Herein, a tree-like Pd dendrites array decorated Pd membrane was constructed as the core device in an electrochemistry assisted gas-fed membrane reactor for butadiene semi-hydrogenation. It reveals that hydrogen atomic sieving effect of this Pd-based membrane under electrochemical condition was the key for semi-hydrogenation. The configuration study of Pd nanostructured membrane demonstrates that the penetration of hydrogen atoms through Pd membrane from electrochemical side to chemical side is affected by the consumption of hydrogen atom in semi-hydrogenation step. Such atomic sieving property of nanostructured Pd membrane with 5.1 times increase in catalytic active surface area brings above 14 times higher in butadiene conversion than that of bare Pd foil, with ≈90 % of butenes selectivity at butadiene conversion ≈98 % over 300 h of H2 -free reaction under 15 mA cm-2 .

H2‐free Semi‐hydrogenation of Butadiene by the Atomic Sieving Effect of Pd Membrane with Tree‐like Pd Dendrites Array

AbstractH2‐free semi‐hydrogenation at room temperature shows great advantage for replacing the thermocatalytic process in industry owing to the high energy and resource saving, however, remains great challenges. Herein, a tree‐like Pd dendrites array decorated Pd membrane was constructed as the core device in an electrochemistry assisted gas‐fed membrane reactor for butadiene semi‐hydrogenation. It reveals that hydrogen atomic sieving effect of this Pd‐based membrane under electrochemical condition was the key for semi‐hydrogenation. The configuration study of Pd nanostructured membrane demonstrates that the penetration of hydrogen atoms through Pd membrane from electrochemical side to chemical side is affected by the consumption of hydrogen atom in semi‐hydrogenation step. Such atomic sieving property of nanostructured Pd membrane with 5.1 times increase in catalytic active surface area brings above 14 times higher in butadiene conversion than that of bare Pd foil, with ≈90 % of butenes selectivity at butadiene conversion ≈98 % over 300 h of H2‐free reaction under 15 mA cm−2.

Refining reaction kinetics of butadiene hydrogenation on zeolite-confined palladium clusters

Palladium clusters confined within the micropores of ZSM-5 in protonic form (Pd@ZSM-5) are designed for the selective hydrogenation of 1,3-butadiene. Greatly enhanced selectivity to butenes at similar conversions is achieved on Pd@ZSM-5 as compared with the conventionally adsorption-derived nanoparticle counterpart (Pd/ZSM-5). Pd@ZSM-5 exhibits lower intrinsic activity that can be leveraged by increasing H2-to-butadiene ratio in the feed without sacrificing butenes selectivity. The size and electronic effects of the Pd species on their catalytic performance are discussed by coupling in situ diffuse reflectance infrared Fourier transform spectroscopy and the detailed reaction kinetics of the hydrogenation of butadiene and 1-butene, and the isomerization of 1-butene. It is revealed that the size and location of the Pd species may play a more decisive role in determining the hydrogenation performance rather than the nature of the surface Pd species. Palladium clusters confined in the zeolites channels do not change the π-bonding configuration of butadiene and the adsorption of H2, but significantly weaken the adsorption strength of both butadiene and the primary product - 1-butene, the key factors responsible for the selective hydrogenation.

Structure-dependence and metal-dependence on atomically dispersed Ir catalysts for efficient n-butane dehydrogenation

Single-site pincer-ligated iridium complexes exhibit the ability for C-H activation in homogeneous catalysis. However, instability and difficulty in catalyst recycling are inherent disadvantages of the homogeneous catalyst, limiting its development. Here, we report an atomically dispersed Ir catalyst as the bridge between homogeneous and heterogeneous catalysis, which displays an outstanding catalytic performance for n-butane dehydrogenation, with a remarkable n-butane reaction rate (8.8 mol·gIr−1·h−1) and high butene selectivity (95.6%) at low temperature (450 °C). Significantly, we correlate the BDH activity with the Ir species from nanoscale to sub-nanoscale, to reveal the nature of structure-dependence of catalyst. Moreover, we compare Ir single atoms with Pt single atoms and Pd single atoms for in-depth understanding the nature of metal-dependence at the atomic level. From experimental and theoretical calculations results, the isolated Ir site is suitable for both reactant adsorption/activation and product desorption. Its remarkable dehydrogenation capacity and moderate adsorption behavior are the key to the outstanding catalytic activity and selectivity.

Kinetics of Liquid-Phase 1-Butene Hydroisomerization over Pd/Al2O3 Catalysts

Liquid-phase 1-butene hydroisomerization to 2-butene is an important approach to utilize cheap and abundant C4 olefins (normally as by-products from refinery processes), and the reaction kinetics is critical to the development of its reactors and catalysts. Herein, kinetics experiments are performed to understand the characteristics of liquid-phase 1-butene hydroisomerization over a commercial Pd/Al2O3 catalyst, and three intrinsic kinetics models are proposed to describe the rates of the hydroisomerization and hydrogenation reactions. The results show that the selectivity toward 2-butene increases with temperature, indicating the hydrogenation reactions are suppressed due to the low partial pressure of hydrogen under high temperature. The fraction of hydrogen in reactants significantly affects 1-butene conversion and 2-butene selectivity, and thus, this effect should be included in kinetics models. Comparing the proposed power-law, dual-site Langmuir–Hinshelwood, and single-site Langmuir–Hinshelwood models, the single-site Langmuir–Hinshelwood model is the best in predicting the experiments, implying that hydroisomerization and hydrogenation reactions may occur at the same type of active sites under the reaction conditions in this work. The activation energies of the hydroisomerization reactions are lower than those of the hydrogenation reaction, and the adsorption enthalpy of butenes is smaller than that of hydrogen.

Carbonaceous deposits on cobalt particles reverse the catalytic patterns in butadiene hydrogenation

Thein situformed carbonaceous deposits on a nitrogen-doped carbon-supported cobalt nanoparticle catalyst dramatically enhanced butenes selectivity and catalyst stability in butadiene hydrogenation.

Ethylene Dimerization and Oligomerization Using Bis(phosphino)boryl Supported Ni Complexes

We report the dimerization and oligomerization of ethylene using bis(phosphino)boryl supported Ni(II) complexes as catalyst precursors. By using alkylaluminum(III) compounds or other Lewis acid additives, Ni(II) complexes of the type (RPBP)NiBr (R = tBu or Ph) show activity for the production of butenes and higher olefins. Optimized turnover frequencies of 640 molethylene·molNi-1·s-1 for the formation of butenes with 41(1)% selectivity for 1-butene using (PhPBP)NiBr, and 68 molethylene·molNi-1·s-1 for butenes production with 87.2(3)% selectivity for 1-butene using (tBuPBP)NiBr, have been demonstrated. With methylaluminoxane as a co-catalyst and (tBuPBP)NiBr as the precatalyst, ethylene oligomerization to form C4 through C20 products was achieved, while the use of (PhPBP)NiBr as the pre-catalyst retained selectivity for C4 products. Our studies suggest that the ethylene dimerization is not initiated by Ni hydride or alkyl intermediates. Rather, our studies point to a mechanism that involves a cooperative B/Ni activation of ethylene to form a key 6-membered borametallacycle intermediate. Thus, a cooperative activation of ethylene by the Ni-B unit of the (RPBP)Ni catalysts is proposed as a key element of the Ni catalysis.

Ni-Loaded 2D Zeolitic Imidazolate Framework as a Heterogeneous Catalyst with Highly Activity for Ethylene Dimerization

Metal–organic frameworks (MOFs) hold great potential in heterogeneous catalysis due to their unique properties and tunable structures. Zeolitic imidazolate frameworks (ZIFs) are series of classical MOFs that have been widely studied, where Zn2+ is coordinated with four imidazoles to form a tetrahedral structure. ZIF-L, one type of ZIF, is known for its unique two-dimensional (2D) leaf-like morphology and large external specific surface area. In this work, we reported a facile and green synthesis of the Ni-loaded ZIF-L (Ni-ZIF-L) catalysts, where water as solvent and product collection by filtration make the preparation easy for large-scale industrial production. Considering the incompatibility of the d8 electron configuration of Ni with the three-dimensional (3D) framework of ZIF-L, Ni can only be selectively anchored to the surface of ZIF-L. The Ni-ZIF-L has shown high crystallinity and 2D leaf-like microflakes similar to those of pure ZIF-L. After systematic analysis, we speculate that the Ni sites in Ni-ZIF-L samples have a square planar configuration, which should be coordinated by two imidazole groups from the framework, one NO3– group, and one free imidazole group. Ni-ZIF-L possesses fully exposed Ni active sites and a large specific surface area, accounting for the good performance for ethylene dimerization. In addition, the large particle size of the Ni-ZIF-L catalyst is beneficial for separation. With the assistance of cocatalyst, Ni-ZIF-L achieves an average ethylene turnover frequency of 330 320 moles of ethylene per mole of Ni per hour (1-butene selectivity >90%)) under 40 °C and 30 bar, comparable to the activity of the benchmark heterogeneous catalyst. The isotope experiments are used to illustrate that the ethylene dimerization catalyzed by Ni-ZIF-L follows the Cossee-Arlman mechanism, which also rationalizes the high catalytic activity and the small amount of isomerization and trimerization product formation.