Ethylene Consumption Research Articles

Differences in Interfacial Reactivity of Graphite and Lithium Metal Battery Electrodes Investigated Via Operando Gas Analysis.

Gases evolved from lithium batteries can drastically affect their performance and safety; for example, cell swelling is a serious safety issue. Here, we combine operando pressure measurements and online electrochemical mass spectrometry measurements to identify the nature and quantity of gases formed in batteries with graphite and lithium metal electrodes. We demonstrate that ethylene, a main gas evolved in SEI formation reactions, is quickly consumed at lithium metal electrodes unless they have been pretreated in the electrolyte. Polyolefins such as polyethylene are suggested as the possible reaction product from ethylene consumption, evidencing another pathway of SEI formation that had been previously overlooked because it does not produce any gas product.

РЫНОК ЭТИЛЕНА В РОССИИ: ОБЗОР, АНАЛИЗ, ПЕРСПЕКТИВЫ

The Russian ethylene market is a strategically important sector, so its detailed study is of considerable interest. Article «Ethylene market in Russia: review, analysis, prospects» by S.T. Gulina is devoted to a comprehensive analysis of the current state and prospects for the development of this market. The study covers key aspects, including analysis of production, production capacity, major eth-ylene producers, consumption, exports, imports and price dynamics. The author, based on the analysis of current trends and projected changes, offers a forecast of market development for the coming years. The work provides valuable information for making informed decisions by specialists working in the field of ethylene production and consumption, as well as for investors interested in the development of this industry.

An exact and vigorous kinetic Monte Carlo simulation to determine the properties of bimodal HDPE synthesized with a dual-site metallocene catalyst

A vigorous and progressed Monte Carlo strategy was developed to precisely simulate the ethylene and 1-butene copolymerization within the presence of hydrogen by dual-site metallocene catalyst. The results showed up that the ethylene and 1-butene consumption rates at the second catalyst site were approximately 5 times higher than at the first site, and hydrogen transfer rates at the first catalyst site were over 3 times more rapid than at the second site. It was found that the most elevated molar percentage of 1-butene inside the copolymers synthesized from the second site was around 12% and within the copolymers gotten from the first site was around 2%. At a steady hydrogen concentration, with 8 times increase in the 1-butene concentration within the initial feed, the overall weight average molecular weight (M‾w) and an overall number average molecular weight (M‾n) extended by approximately 50% and 40%, respectively. Besides, at a consistent 1-butene concentration, with 8 times increase in the concentration of hydrogen, M‾w and M‾n diminished by approximately 18% and 22%, separately. Due to the synthesis of two groups of chains with distinct molecular weights, the overall dispersity (Đ) was slightly higher than the dispersity resulting from each catalyst site (1.5–2.1). With increasing 1-butene concentrations, the overall bimodal molecular weight distribution (MWD) widened, and the peak sizes grew smaller and moved towards higher molecular weights. As hydrogen concentration increased, peaks became taller and move toward shorter chain lengths. It was observed that the first site created chain lengths between 102 and 103 while the second site generated chain lengths between 102 and 106. As the concentration of 1-butene was increased in the initial feed, the number of short chain branching per 1000 carbon atoms (SCB/1000C) increased from 10 to 50. Compared to the first site, there were 5 times as many SCBs at the chains produced from the second site. By diminishing the ratio of ethylene to 1-butene, the melt index (MI) tended towards smaller numbers (0.2≤MI≤2). With an increase in the ratio of ethylene to 1-butene and ethylene to hydrogen, the weight fraction of crystals raised from 67.4 to 69.5% and diminished from 71 to 69.5%, respectively. At last, increasing the temperature led to a diminish in molecular weight, a narrowing of the bimodal MWD, an increment within the thickness and weight fraction of crystals, and an increment within the density of HDPE.

Effects of ethylene addition and dilution on the explosion characteristics of ethane-ethylene mixtures

The properties of an ethane-ethylene mixture were analyzed under varying equivalence ratios (ranging from 0.58 to 1.4) and ethylene volume fractions (ranging from 0% to 100%) with varying dilution ratios, using a 20-liter apparatus. The study aimed to understand the explosion characteristics of the mixture and to identify the elementary reactions that have the most significant impact on the rise in pressure and ethylene consumption during the explosion process. The results showed that adding ethylene increases the maximum explosion pressure and broadens the flammability limit range. In addition, the work investigated the effects of diluting the mixture with either nitrogen or carbon dioxide. It was found that carbon dioxide has a higher specific heat capacity compared to nitrogen, which enhances the heat absorption capacity of the mixture. The collision of carbon dioxide molecules with the activated radicals in the reaction transfers energy from the radicals to carbon dioxide, reducing the radicals' activity and causing a more significant dilution effect than nitrogen. Finally, a chemical kinetics analysis of the premixed gas using the UC San Diego mechanism revealed that the production rate of key free radicals gradually increases with the addition of ethylene, enhancing the explosion reaction intensity.

Ethylene oligomerization over mesoporous FeNi-BTC catalysts: Effect of the textural properties of the catalyst on the reaction performance

Mesoporous FeNi-1,3,5-benzenetricarboxylates (FeNi-BTCs) with different Fe/Ni ratios were prepared, and their catalytic activities in ethylene oligomerization were evaluated. The textural properties of the bimetallic FeNi-BTC were considerably affected by the Fe/Ni ratio, exhibiting a volcano relationship, with the maximum specific surface area, pore volume, and diameter observed at Fe/Ni = 10/90. The enhanced textural properties of the FeNi-BTC catalyst resulted in accelerated ethylene oligomerization and an increased C6–C8 oligomer selectivity. Using the Fe10Ni90-BTC catalyst, the rate of ethylene consumption and C6–C8 oligomer selectivity reached as high as 2823 g C2H4/g Ni h and 49%, which were approximately four- and two-fold higher than those of Ni-BTC, respectively. The remarkable reaction performance of the Fe10Ni90-BTC catalyst could be rationalized in terms of its well-defined mesoporous structure, which could decrease the mass transfer resistance and thereby facilitate intrapore ethylene diffusion during ethylene oligomerization. These results clearly demonstrate the potential of the FeNi-BTC catalyst in promoting ethylene oligomerization with a high activity and selectivity towards C6∼C8 oligomers. In the catalyst recycling study, whereas the catalytic activity decreased due to the partial deformation of the FeNi-BTC catalyst with repeated recycling, the selectivity towards C6+ oligomers gradually increased.

How do zeolite-templated carbons grow?

Major insights into the formation mechanism of zeolite-templated carbons (ZTCs) were achieved via a thorough ex situ kinetic study of the hybrid (carbon/zeolite) and carbon materials. In depth characterization of the chemical, electrical, textural, and morphological properties of the materials allowed us to draw a precise picture of the key steps of the ZTC formation. An in situ time resolved GC study enabled us to achieve complementary insights into the ethylene consumption and hydrogen production during ZTC synthesis. Three stages could be disclosed: nucleation, growth and condensation. During nucleation, individual polyaromatic hydrocarbons (PAHs) develop through the aromatization of ethylene. These PAHs present high spin concentration and react upon zeolite dissolution, leading to unstructured carbon particles of undefined morphology. These carbons feature persistent radicals. During growth, the PAHs evolve to form more complex rylene-type molecules. Typical structural, textural, and morphological features of ZTCs start to emerge during this second stage. The evolution of electrical conductivity of hybrid materials indicates partial condensation of PAHs throughout the zeolite crystals leading to their connection. The carbon materials achieved during the second stage can be described as composites of ZTCs and randomly reacted PAHs. Condensation, which is importantly induced by heat treatment, triggers full connection of the ZTC network. Textural, morphological, structural, and electrical features develop, which result directly from zeolite templating. Final ZTCs feature carbonyl functionalization, which is inherent to the zeolite dissolution step and probably results from radical quenching with water.

Kinetics of ethylene oligomerization over Ni-H-Beta catalysts

We report the kinetics of ethylene oligomerization over the Ni-H-Beta for temperatures ranging between 50 and 100 °C and pressures ranging between 5 and 28 atm. According to our results, the apparent activation energies involved in the formation of butene, hexene, and octene are 44, 78, and 60 kJ.mol−1, respectively. The measured lower apparent activation energy for butene formation relative to hexene and octene is a likely result of the fact that the measured butene formation is not the true (forward) rate of formation of butene but it the net rate because of the consumption of butene in secondary reactions. Analysis of the reaction order indicates that participation of butene in chain-growth reactions takes place via desorption followed by re-adsorption of butene on the catalyst. The results also indicate that hexene undergoes a similar process. In the present paper, we refer to the pathway involving co-oligomerization of butene and hexene as “cascade co-oligomerization”. Based on these findings, we proposed a reaction network and modeled reaction rate expressions for ethylene consumption and butene, hexene, and octene formation based on the construction of a micro-kinetic model. We calculated the kinetic parameters involved in the reaction network proposed and found evidence that the formation of octene proceeds mainly via the “cascade co-oligomerization” of re-adsorbed butene with ethylene.

МОДЕЛЮВАННЯ ХІМІКО-ТЕХНОЛОГІЧНИХ ПРОЦЕСІВ У SCADA ЗА ДОПОМОГОЮ ТЕХНОЛОГІЇ OPEN PLATFORM COMMUNICATIONS

The subject of study in the article are methods for integrating mathematical models of chemical-technological processes implemented in universal modeling programs into modern SCADA systems for developing and improving methods for controlling these processes. The goal is to develop a control system for the synthesis of acetylene in a kinetic reactor, based on a computer model created in universal modeling programs and integrated into SCADA using open platform communications (OPC) technology. Tasks: to create a mathematical model of the process of synthesis of acetylene based on the selected universal modeling program; to develop a way to integrate the resulting model into modern SCADA using OPC technology; to develop in SCADA a control system for the process of synthesis of acetylene according to a mathematical model as part of a functional human-machine interface and control subsystem algorithms; get transient graphs and prove the efficiency of the control system. Conduct a process study using a mathematical model. The methods used are computer simulation of technological processes; OPC technology; SCADA based management. The following results are obtained. A control system for the acetylene synthesis process based on SCADA Trace-Mode and a mathematical model implemented in the ChemCAD package has been developed, while the model - control system information exchange is implemented based on OPC technology. Checked and proved the efficiency of the resulting control system. A mathematical study of the process was carried out, an experimental dependence of the yield of the final product, acetylene, on the temperature, and consumption of raw materials at the inlet of the reactor was established. Conclusions. The novelty of the results is as follows. A new method is proposed for integrating mathematical models implemented in the ChemCAD modeling package into modern SCADA, based on OPC technology. A study of the process of acetylene synthesis by a mathematical model was carried out, experimental dependences of the acetylene yield on temperature and ethylene consumption at the inlet of the synthesis reactor were obtained. An analysis of the obtained experimental dependences showed the need to use cascade control algorithms to increase the efficiency of controlling the process of acetylene synthesis in a kinetic reactor.

Kinetic Modeling of Ethylene Epoxidation Kinetics as a Function of Chlorine Coverage over a Highly Promoted Silver Catalyst

Kinetic modeling of previously reported data demonstrate that chlorine exhibits an electrostatic influence, rather than solely ensemble site blocking, to improve the selectivity of ethylene epoxidation over promoted silver catalysts. Kinetic models that neglect the impact of surface chlorine content on either oxygen dissociation or ethylene adsorption enthalpies are unable to describe observed changes in the apparent reaction orders of ethylene consumption. Models that employ solely ensemble effects to adjust product selectivity with chlorine content falsely predict a simultaneous maximum in ethylene oxide (EO) and carbon dioxide synthesis rates with respect to chlorine coverage at 10–15% of a monolayer of chlorine. Incorporating electronic effects of chlorine on the transition states of the selectivity-determining steps into the model, however, properly describes the measured rate trends with surface chlorine content. Specifically, the model reflects the maxima observed in ethylene oxide synthesis rate with the concomitant monotonic decrease in combustion rates with increasing chloride content. Slight improvements to model predictions by combining ensemble and electronic effects on EO selectivity with increasing Cl coverage suggest that both effects may be relevant in combination but that ensemble effects alone cannot describe the observed behavior.

EPR spectroscopic study of Ni(I) species in the catalyst system for ethylene polymerization based on α-diimine Ni(II) complex activated by MMAO

Using EPR spectroscopy, nickel(I) species formed in the catalyst system 1/MMAO for ethylene polymerization has been investigated (1 = LNiBr2, L = 1,4-bis-2,4,6-dimethylphenyl-2,3-dimethyl-1,4-diazabuta-1,3-dien). It has been shown that diamagnetic cationic complex [LNiII-tBu]+[MeMMAO]– (2) persists in system 1/MMAO at low temperatures, but rapidly decays at 25 °C to give new EPR active species 3 (major product) and 4 (minor product). Species 3 is a nickel(I) complex with the proposed structure [LNiI(S)]+[MeMMAO]– (S = solvent), whereas 4 is L(•−)AlMe2 species. Upon the addition of ethylene, complex 3 partially reversibly converts into the adduct [LNiI(C2H4)]+[MeMMAO]– (5). After ethylene consumption, species 3 restores its original concentration.

Effect of Ethanol on Ethylene Consumption in Premixed Laminar Flames of Ethylene and Ethanol: A Modeling Study

The effect of ethanol on the ethylene consumption in fuel-rich, premixed, laminar, burner-stabilized flames at atmospheric pressure was investigated. A pure ethylene flame and three ethylene/ethanol flames with different ethanol fractions were simulated at the same equivalence ratio. The results showed that the different reaction rates for ethylene consumption in the flames were related to the reaction kinetics in these flames with an insignificant thermal effect. Changes in key radical concentrations in the flames were observed depending upon the initial ethanol mole fraction in the fuel, and the reaction pathways responsible for the production and destruction of ethylene were identified. The chemical behaviors differed significantly at different flame heights above the burner. At the flame height with a temperature of 769 K, a decrease in the OH concentration was responsible for the reduction in the reaction rate for ethylene consumption with the addition of ethanol. At the flame height with a temperature of 1470 K, the normalized ethylene concentration in the flames increased with the increase of the initial ethanol fraction in the fuel, the reason for which appeared to be the decomposition reactions into ethylene rather than the changes of species pool in the flames.

Nickel complexes based on hyperbranched salicylaldimine ligands: Synthesis, characterization, and catalytic properties for ethylene oligomerization

A series of new nickel complexes based on hyperbranched salicylaldimine ligands have been prepared in good yields and characterized by FT-IR, 1H NMR, UV, ESI-MS and TGA. Upon activation with methylaluminoxane (MAO) or diethylaluminum chloride (DEAC), these new precatalysts showed high activity in ethylene oligomerization, and notably remarkably high selectivity of high carbon olefins in the presence of DEAC. The catalytic performance was substantially affected by the solvent type, reaction conditions and the structure of catalyst. Under optimized conditions, precatalyst C1 led to TOF = 13.65 × 105 g/mol Ni·h and 21.53% selectivity for high carbon olefins. The result of thermal analysis revealed that the complex C1 was stable up to 298.4 °C. The research result of the kinetics of ethylene oligomerization found that the pressure drop of ethylene consumption sharply increased in the initial stage, however with the prolonged reaction time, the pressure drop of ethylene consumption varied a little.

Effect of catalyst selectivity on exergetic and exergoeconomic evaluation of ethylene oxide/ethylene glycol process

Ethylene oxide (EO) is an important petrochemical used for different applications in chemical process industries. EO production cost is higher due to price of ethylene and silver catalyst. Safety constraints limit conversion of ethylene to EO in the reactor. Ethylene consumption in the process is gradually increases due to reduction in catalyst selectivity. Exergy analysis is used as a tool for optimisation of the EO process considering above hurdles. Half of the EO produced in the world is converted into ethylene glycol (EG), hence integrated plant of EO-EG is considered in the present study. Exergy efficiencies of two EG manufacturing processes are compared. Recovery of ethylene from purge gas is also analysed based on exergy. EXCEM method is used for economic evaluation of the process. A proposed parameter EGRex is useful to decide the catalyst life based on exergy loss in the EO reactor and income generated in the process.

Detailed influences of ethanol as fuel additive on combustion chemistry of premixed fuel-rich ethylene flames

To better understand potential pollutant formations during combustion of conventional hydrocarbon fuels blended with oxygenated fuels, detailed influences of ethanol as fuel additive on small polycyclic aromatic hydrocarbons (PAHs) precursors, aldehydes, ketene and other important intermediate species in premixed fuel-rich low-pressure ethylene flames are distinguished among dilution, thermal and chemical effects of additives. Dominant effects of ethanol addition on each species are underlined respectively. Ethylene oxidation process is delayed when ethylene is substituted by ethanol. The influence of ethanol dilution and thermal effects on ethylene consumption are larger than chemical effects. CO mole fractions slightly decrease mainly as a result of dilution and thermal effects of added ethanol. The reductions in small PAHs precursors (acetylene and propargyl) are attributed to dilution and thermal effects of ethanol addition instead of chemical effects. The ethanol chemical effects promote formations of hazardous pollutants formaldehyde and acetaldehyde, and especially are responsible for the significant increase of acetaldehyde. C2H6, C4H2 and C4H4 mole fractions decrease in a similar way with acetylene and propargyl as ethanol is added. Ethanol used here only serves as a prototype of oxygenated additive, and identification method in this work is more universal which can be easily extended for analyzing other fuel blends of hydrocarbon and oxygenated fuels.

The evolutionary development of chain microstructure during tandem polymerization of ethylene: A Monte Carlo simulation study

Employing a Kinetic Monte Carlo (KMC) simulation algorithm, tandem polymerization of ethylene is thoroughly investigated. To do this, the evolution of ethylene copolymerization is evaluated in terms of ethylene consumption and 1-hexene accumulation. The results obtained are in good agreement with the existing experimental kinetic data. It is revealed that the pre-trimerization time is a key factor in controlling the architecture of copolymer chains. Moreover, the precise computation of instantaneous and cumulative comonomer contents along with the chemical composition distribution of simulated copolymers provides a comprehensive image of the growing chains during tandem polymerization. A well-established crystallization fractionation (CRYSTAF) analysis mathematical model is applied to delve into the molecular architecture and the crystallization fractionation behavior of the produced polyolefins.

Synthesis of ethylene/1‐octene copolymers with controlled block structures by semibatch living copolymerization

A kinetic model was developed for the living copolymerization of ethylene/1‐octene using the fluorinated FI‐Ti catalyst system, bis[N‐(3‐methylsalicylidene)‐2,3,4,5,6‐pentafluoroanilinato] TiCl2/dried methylaluminoxane is presented. The model was first validated by batch polymerization experiments. Kinetic parameters were estimated from the model correlations with online ethylene consumption rates and end‐of‐batch copolymer molecular weight. The model was then used to calculate the microstructural properties of ethylene/1‐octene copolymers with controlled composition profiles (uniform, diblock, and step triblock), which were synthesized using sequential comonomer feeding policies in semibatch copolymerization. The synthesized block copolymers had the exact composition distributions and molecular weights as the model simulated. It was demonstrated that the polymer chain microstructure in the living copolymerization of olefins could be precisely regulated by using semibatch comonomer feeding policies. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4686–4695, 2013

New clay‐supported Ziegler–Natta catalyst for preparation of PE/Clay nanocomposites via in situ polymerization

AbstractPolyethylene/clay (PE/Clay) nanocomposites were prepared by the in situ polymerization of ethylene using the new Clay/butyl octyl magnesium (BOM)/Chloroform/EtOH/TiCl4/tri ethyl aluminum (TEA) catalyst system in heptane where BOM and TEA were the support for the clay modification and cocatalyst, respectively. The influence of the modified clay using BOM on the catalyst and polymerization was investigated. Also, the effect of temperature, pressure, hydrogen, and the molar ratios of TEA/Ti on the catalyst yield and ethylene consumption (polymerization rate) were studied. It was found that the above clay‐supported catalyst was an efficient Ziegler–Natta type catalyst due to its suitable yield for the polymerization of ethylene toward the production of the PE/Clay nanocomposites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Influence of Process Parameters on the Reaction Kinetics of the Chromium‐Catalyzed Trimerization of Ethylene

In this paper we report the results of an extensive experimental kinetic study carried out on the novel ethylene trimerization catalyst system, comprising the chromium source [CrCl(3)(thf)(3)] (thf=tetrahydrofuran), a Ph(2)P-N(iPr)-P(Ph)-N(iPr)H (PNPNH) ligand (Ph=phenyl, iPr=isopropyl), and triethylaluminum (AlEt(3)) as activator. It could be shown that the initial activity shows a first-order dependency on the ethylene concentration. Also, a first-order dependency was found for the catalyst concentration. The initial activity follows a typical Arrhenius behavior with an experimentally determined activation energy of 52.6 kJ mol(-1). At elevated temperatures (ca. 80 degrees C), a significant deactivation was observed, which can be tentatively traced back to a ligand rearrangement in the presence of AlEt(3). After a fast initial phase, a pronounced 'kink' in the ethylene-uptake curve is observed, followed by a slow, almost linear, further increase of the total ethylene consumption. The catalyst composition, in particular the ligand/chromium and the cocatalyst/chromium molar ratio, has a strong impact on the catalytic performance of the trimerization of ethylene.

Responses of ethylene and methane consumption to temperature and pH in temperate volcanic forest soils

SummaryThere is limited knowledge about the consumption and interaction of methane (CH4) and ethylene (C2H4) in forest soils under disturbances of temperature and acidification. Temperate volcanic forest topsoils (0‐5 cm) sampled under different tree species (e.g. Pinus sylvestris, Cryptomeria japonica and Quercus serrata) were used to study the capacities for CH4 and C2H4 consumption and their sensitivity to temperature and pH. We also studied the responses of soil nitrogen (N) transformations to temperature and relationships to consumption of both CH4 and C2H4. The C2H4 consumption rates increased with temperature up to 35oC, whereas the optimum temperature for CH4 consumption rates was approximately 25oC. Both Q10 values and activation energies for CH4 consumption rates over the range 5 to 25oC were larger than corresponding values for C2H4 consumption rates. The rates of nitrous oxide (N2O) and nitric oxide (NO) evolution and net N mineralization in the soils increased exponentially with temperature up to 35oC, with relatively large Q10 values and activation energies for NO evolution. In these forest topsoils, rates of CH4 and C2H4 consumption at pH < 4.0 were negligible, and the pH optimum for both consumptions varied from 5.5 to 6.2. Most of the tested forest soils had an optimum pH for CH4 and C2H4 consumption that was above natural pH values, which indicated that soil acidification would inhibit CH4 and C2H4 consumption in situ. There was a high rate of net C2H4 evolution from forest soils acidified experimentally to pH < 4.0, particularly from Cryptomeria japonica forest soil, and 67% of the variation in C2H4 evolution rates could be accounted for by the increase in soil water‐soluble organic carbon concentrations. Previous studies have shown that addition of C2H4 in headspace gases can inhibit atmospheric CH4 consumption in such forest soils. Hence, the evolution of C2H4 from temperate volcanic forest soils at decreasing pH can exacerbate inhibition of the soil atmospheric CH4 consumption in situ.

O‐Acylated 2‐Phosphanylphenol Derivatives – Useful Ligands in the Nickel‐Catalyzed Polymerization of Ethylene

AbstractThe title ligands were prepared by O‐acylation of 2‐diphenylphosphanyl‐4‐methylphenol (1) or directly by double lithiation of 2‐bromo‐4‐methylphenol and stepwise coupling with ClPPh2 and ClP(O)Ph2 or RC(O)Cl (R = Me, tBu, Ph, 4‐MeOC6H4) to afford diphenylphosphinate 2 and carboxylic esters 3a–d. X‐ray crystal structure analyses of 3b–d show conformations in which the P‐phenyl substituents are rotated away from the ester group and the C(O)O π planes are nearly perpendicular to the phenol ring π plane. O‐Acylated phosphanylphenols 2 and 3a–d form highly active catalysts with Ni(1,5‐cod)2 (as does 1) for polymerization of ethylene, whereas phosphanylphenyl ethers do not give catalysts under the same conditions. The reason is the cleavage of the O‐acyl bond upon heating with nickel(0) precursor compounds in the presence of ethylene. The precursors are P‐coordinated Ni0 complexes, which are formed at room temperature, such as 4d obtained from 3d and Ni(cod)2 (in a 2:1 molar ratio), and characterized by multinuclear NMR spectroscopy. Upon heating in the presence of ethylene, the precatalysts are activated. Catalysts 2Ni and 3a–dNi convert ethylene nearly quantitatively, 2Ni slowly, and 3a–dNi rapidly, into linear polyethylene with vinyl and methyl end groups, and in the latter case, C(O)R end groups are also detectable. This proves insertion of Ni0 into the O–C(O)R bond of 3a–d ligands for formation of the primary catalyst. Termination of the first chain growing cycle by β‐hydride elimination changes the mechanism to the phosphanylphenolate–NiH initiated polymerization providing the main body of the polymer. A small retardation in the ethylene consumption rate with 3a–dNi catalysts relative to that observed for 1Ni and stabilization of the catalyst, which gives rise to reproducibly high ethylene conversion, is observed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)