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The stretching‐induced phase transition from tetragonal Form II to hexagonal Form I and the evolution of corresponding crystallite orientation were studied for the butene‐1/ethylene random copolymer with 1.5 mol % ethylene by using a combination of tensile test and in situ wide‐angle X‐ray diffraction. Three orientation pathways were distinguished for II‐I phase transition, including phase transition accomplishing within off‐axis oriented crystallites (Orientation Pathway 1), phase transition with simultaneous formation of highly oriented crystallites (Orientation Pathway 2), and phase transition occurring within the highly oriented crystallites already formed (Orientation Pathway 3). The kinetics of II‐I transition was correlated with the macroscopic mechanical response, which exhibits a strong dependence on orientation. In Orientation Pathway 1, the triggering of phase transition corresponds to the mechanical yielding. More interestingly, the kinetics of transition exhibits the identical dependence on stress. However, in Orientation Pathways 2 and 3, appearance of the highly oriented crystallites substantially alters transition kinetics, which is tentatively associated with the stress bearing by interstack tie chains. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 116–126

Herein, we report the catalytic decarboxylation of γ-valerolactone (GVL) over Zn/ZSM-5 to butene, followed by aromatization at high yield with co-feeding of water. An evaluation of the catalytic performance after prolonged periods of time showed that a water molecule is essential to maintain the decarboxylation and aromatization activities and avoid rapid catalyst deactivation. Synchrotron X-ray powder diffraction and Rietveld refinement were then used to elucidate the structures of adsorbed GVL and immobilized Zn species in combination with EXAFS and NMR spectroscopy. A new route for the cooperative hydrolysis of GVL by framework Zn-OH and Brønsted acidic sites to butene and then to aromatic compounds has thus been demonstrated. The structures and fundamental pathways for the nucleophilic attack of terminal Zn-OH sites are comparable to those of Zn-containing enzymes in biological systems.

The gas-phase deoxydehydration of 2,3-butanediol to butene was investigated in a plug flow reactor over SiO2-supported vanadium oxide, γ-alumina, P/ZSM-5, and MgO catalysts with acid/base sites of varying strengths. 5 wt % vanadium on SiO2 (i.e., 5V/SiO2) showed the best performance with 100 % conversion and up to 45.2 % butene selectivity. The combination of weak acid sites and polymeric VOx surface species provided the 5V/SiO2 catalyst with bifunctional capabilities to achieve both dehydration and transfer hydrogenation, which allowed it to catalyze the deoxydehydration of 2,3-butanediol to butene even in the absence of H2. As 2,3-butanediol is a common yet underutilized biomass product, this reaction may provide a viable route for a biomass-to-chemicals application for 2,3-butanediol.

Few catalytic transformations can be efficiently catalyzed by both homogeneous or heterogeneous technologies. Short olefin oligomerization promoted by nickel-based catalysts is among them. Homogeneous and heterogeneous catalysis are often opposed in terms of activity, active-site description or recyclability, traditionally mentioned as "homogeneous vs. heterogeneous". Unlike previous studies, we propose here to emphasize the similarities between both catalysis by comparing industrially representative results obtained in continuous flow-mode and in similar mild thermic conditions. A fine analysis of not only primary products of olefins oligomerization, but also a set of secondary products obtained in experimental assays completed with recently published results of DFT calculations prompted us to postulate a common mechanistic pathway for nickel-catalyzed ethylene oligomerization. Heterogeneous metallic ethylene oligomerization, for which nickel active sites identification has indeed long been under debate, seems to follow the Cossee-Arlman mechanism, well accepted as major mechanism in homogeneous counterpart. This analysis allowed us to design an unprecedent heterogeneous catalyst active for ethylene and butene oligomerization.

SSCI-VIDE+CDFA+ADO:MET:NES:FRA; International audience; This article reports a detailed study on the reactivity of levulinic acid and cellulose with 1-butene and iso-butene for the catalytic formation of sec-and tert-butyl levulinates. The influence of catalyst type and various solvent conditions have been investigated to assess the potential of a sustainable transformation. A very simple and efficient procedure was discovered by using reusable Amberlyst-15 in the absence of solvent to form, from levulinic acid and iso-butene, tert-butyl levulinate (70% yield), a compound very difficult to prepare by other means. sec-Butyl levulinate (66% yield) was obtained by using Amberlyst-15 in g-butyrolactone as a biosourced solvent. The original procedure was also extended notably by directly using cellulose as a reactant. In the presence of a catalytic amount of H2SO4, it was possible to form sec-butyl levulinate (19% yield) from 1-butene in a more efficient way than by using the alcohol as an esterifying agent.

We report the green synthesis of ZnO supported Ni-Pd alloy nanoparticles for the gas-phase selective hydrogenation of 1, 3- butadiene. The supported catalysts were synthesized through a simple bio-reduction route using Cinnamomum Camphora leaf extract. X-ray diffraction, scanning and transmission electron microscopy and energy dispersed X-ray were used to characterize and verify the nature of the catalysts. The results showed that the Ni-Pd alloy particles were 3.2 ± 0.7, 3.4 ± 0.3 and 3.8 ± 0.6 nm for Ni1Pd1, Ni1Pd3 and Ni3Pd1 respectively. FTIR analysis revealed that stretching vibration bands such as C-H,-C=C-, O-H, -C-O- O remained on the surface acting as stabilizer. The influence of some reaction variables, such as type of S-Pd bimetallic catalyst, type of metal oxide support and reaction temperature, on the hydrogenation activity and selectivity towards total butene (trans-2-butene, 1-butene and cis-2-butene) is investigated. The bioreduction supported catalysts showed excellent catalytic activity and selectivity to butene in the selective hydrogenation of 1,3 butadiene. The calculated total butene selectivity was above 80% for all supported S1-Pd1 catalyst compared to 46.92 % for monometallic Pd/ZnO catalyst. In addition, the Ni1-Pd1/ZnO catalyst presented the best butene yield 88.90 % which was 1.9 times that of Pd/ZnO catalyst. Moreover, it maintained stability over a 10 h durability experiment.

This work proposed a strategy to improve the yield of light olefins of industrial methanol to propylene process by reducing the olefins recycled back into the main reactor and appending an olefin cracking reactor. The heterogeneous fixed-bed model was employed to simulate the reactors with a robust mathematical procedure developed to determine the reactor configuration and the recycle flow rates of the olefins. Two methods were proposed for the modulation: the recycle ratio and species of the olefins, respectively. Results show that the yield of C2–C3 olefins can be improved up to 70% from the basement of about 60% when the ratio is reduced from 100% to less than 23% or when only butene apart from pentene and hexene is recycled back into the main reactor, and the latter method is more effective as its catalyst requirement is seven times less than the former's in the appended cracking reactor. © 2016 American Institute of Chemical Engineers AIChE J, 63: 306–313, 2017

Background In the post-oil society, the methanol-to-olefin (MTO) conversion is a successful non-oil route for the production of ethene, propene and butene, which are important chemicals in modern chemical industry. Recently, the global demand for propene increased, which makes high propene selectivity attractive in the MTO conversion. However, looking for an effective catalyst is the main challenge. Results H-MCM-22 zeolite was dealuminated with nitric acid, oxalic acid and ammonium hexafluorosilicate (AHFS). Then, the parent and dealumianted samples were examined in the MTO. The results show that the total acid amounts decreased and the distribution of Bronsted acid sites in the pores of H-MCM-22 are reregulated after the different dealumination procedures. The results of thermogravimetric (TG) of the spent samples demonstrated that H-MCM-22 (10A) dealumination with 10 mmol/L AHFS solution has the lowest coking rate and coke selectivity, which makes it exhibit the longest lifetime (54 h), and highest propene and butene selectivity (71.8%). Conclusion Dealumination with AHFS is an effective method for H-MCM-22. Because it can eliminate almost all the extra-framework aluminum species and concentrate the Bronsted acid sites in the sinusoidal channels which promotes the propene and butene formation with a resistance to carbonaceous deposition in the MTO reaction.

The oxidative dehydrogenation of a C4 raffinate-2 consisting of n-butane, 1-butene, and 2-butene was conducted in a two-zone fluidized bed reactor using a Mo-V-MgO catalyst. This study reports the influence of the operating conditions temperature, hydrocarbon inlet height, and oxygen/hydrocarbon molar ratio on the product distribution, in particular on the formation of 1,3-butadiene. Axial concentration profiles were measured to elucidate the reaction sequence in the fluidized bed.

The oxidative dehydrogenation of a 1-butene/trans-butene (1:1) mixture to 1,3-butadiene was carried out in a two-zone fluidized bed reactor using a Mo-V-MgO and a γ-Bi2MoO6 catalyst. The significant operating conditions temperature, oxygen/butene molar ratio, butene inlet height, and flow velocity were varied to gain high 1,3-butadiene selectivity and yield. Furthermore, axial concentration profiles were measured inside the fluidized bed to gain insight into the reaction network in the two zones. For optimized conditions and with a suitable catalyst, the two-zone fluidized bed reactor makes catalyst regeneration and catalytic reaction possible in a single vessel. In the lower part of the fluidized bed, the oxidation of coke deposits on the catalyst as well as the filling of oxygen vacancies in the lattice can occur. The oxidative dehydrogenation reaction takes place in the upper zone. Thorough particle mixing inside fluidized beds causes permanent particle exchange between both zones. © 2016 American Institute of Chemical Engineers AIChE J, 63: 43–50, 2017

Highly dispersed MoO3 on SiMCM-41 was applied to the dehydration of 2-butanol. MoO3 /MCM-41 catalysts were prepared using a modified atomic layer deposition method. The structural characteristics of MoO3 supported on SiMCM-41 were examined by inductively coupled plasma spectrometry, nitrogen adsorption, X-ray photoelectron spectroscopy, and X-ray diffraction. The textural characteristics of SiMCM-41 were retained after loading with MoO3 . Ammonia temperature-programmed desorption and Fourier transformation infrared spectroscopy of adsorbed pyridine showed that Lewis acid sites were formed on the MoO3 /MCM-41 catalysts. Among the MoO3 /MCM-41 catalysts, the MoO3 (16.4 wt %)/MCM-41 catalyst showed the highest catalytic activity for butene synthesis from 2-butanol dehydration due to the largest number of acid sites.

The gas-phase elimination of 2-methyl-2-propenal catalyzed by HCl yields propene and CO gas, while E-2-pentenal with the same catalyst gives butene and CO gas. The kinetics determinations were carried out in a static system with the reaction vessels deactivated with allyl bromide and the presence of the free radical inhibitor toluene. Temperature and pressure ranges were 350.0–410.0 °C and 34–76 Torr. The elimination reactions are homogeneous and unimolecular, and follow a first-order rate law. The rate coefficients for the reactions are expressible by the following Arrhenius equations: Data from the kinetic and thermodynamic parameters of these catalyzed elimination reactions implies a mechanism of a concerted five-membered cyclic transition state structure for the formation of the corresponding olefin and carbon monoxide. Copyright © 2015 John Wiley & Sons, Ltd.

In this study, bis(diphenylphosphinemethyl)dimethyl silane (L1) and its palladium(II) halide complex, L1/PdCl2 (C1), were synthesized and characterized. Single-crystal X-ray analysis of the complex revealed bidentate coordination at the Pd center. In combination with methylaluminoxane (MAO) as co-catalyst, C1 exhibited excellent catalytic activity and selectivity for ethylene dimerization toward butene. The maximum catalytic activity obtained from the C1/MAO system for ethylene dimerization to yield butenes was 7.33 × 105 g/(molPd·h). The selectivity toward butene remained stable and high (> 96%) over the various conditions.

A novel gas-phase process has been developed that allows direct two-step conversion of butane into pentanals with high activity and selectivity. The process consists of alkane dehydrogenation over a heterogeneous Cr/Al2O3 catalyst followed by direct gas-phase hydroformylation using advanced supported ionic liquid phase (SILP) catalysis. The latter step uses rhodium complexes modified with the diphosphite ligands biphephos (BP) and benzopinacol to convert the butane/butene mixture from the dehydrogenation step efficiently into aldehydes. The use of the BP ligand results in improved yields of linear pentanal because SILP systems with this ligand are active for both isomerization and hydroformylation. © 2014 American Institute of Chemical Engineers AIChE J, 61: 893–897, 2015

This article reports the activity, reaction mechanism and reaction kinetics of 2-butene metathesis over tungsten oxide containing mesoporous silica (SBA-15) catalyst. Physicochemical characterisation of the catalyst indicates that the dispersion and nature of tungsten oxide species on the catalyst are mainly responsible for the metathesis activity. The ample availability of Bronsted acid sites created by tetrahedrally co-ordinated tungsten species also enhances the metathesis reaction. The product analysis indicates that lower temperature favours the butene isomerisation, while higher temperature is required for metathesis. The high temperature is also responsible for cracking reactions. A kinetics model is developed based on the experimental observations and the possible reactions including isomerisation, metathesis and cracking. The model parameters are estimated by fitting the experimental data implemented in MATLAB. The estimated apparent activation energy of 2-butene isomerisation reaction was found to be the lowest (39.4 kJ/mol) among the competing reactions. The activation energy of cross metathesis of 2-butene and 1-butene, self-metathesis of 1-butene and 2-butene cracking are 71.3, 176.9 and 73.1 kJ/mol, respectively. These results are consistent to the product selectivity and the proposed reaction scheme, which suggests that the isomerisation of 2-butene gives 1-butene and it further reacts (cross metathesis) with 2-butene to produce propylene.

Alkylate is an important clean blending component of gasoline due to the increased statutory reduction of the content of aromatics and olefins in commercial gasoline. The alkylation of isobutane with 2-butene catalyzed by a composite ionic liquid was investigated. The composite ionic liquid showed efficient catalytic performance at a short contact time (10–60 s). The optimal conditions were: reaction temperature 15°C, contact time 20 s, ionic liquid to hydrocarbon volume ratio 1:1, and isobutane to olefin mole ratio 54:1. Under these optimal reaction conditions, the butene conversion was 100%, the yields of C8 and trimethylpentanes were 88.9 and 82.0%, respectively, the ratio of trimethylpentane to dimethylhexane was 11.9, and the alkylate research octane number (RON) was 97.3. A correlation model is developed to predict the product yields and the alkylate RON. The correlation model shows a low calculation error. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2244–2253, 2014

Tridentate ligands 4-R1-6-R2-2-{[trans-2-(isoindolin-2-yl)-1,2-diphenylethylimino]methyl}phenol [R1 = R2 = H, H(La); R1 = R2 = tert-butyl, H(Lb); R1 = Ph, R2 = H, H(Lc)] in which a substituted salicylaldimine moiety and an isoindoline are linked by a trans-1,2-diphenylethylene moiety have been prepared. Deprotonation of these tridentate ligands H(La)–H(Lc) by NaH at room temperature in tetrahydrofuran (THF), followed by treatment with 1 equiv. of [(PPh3)2NiX2] (X = Cl, Br, I) at room temperature afforded the desired nickel complexes [(L)NiX] (X = Cl, L = La, 1; X = Cl, L = Lb, 2; X = Cl, L = Lc, 3; X = Br, L = Lb, 4; X = I, L = Lb, 5) in moderate yields. The structures of 2 and 4 were unequivocally confirmed by single-crystal X-ray diffraction in the solid state. The metal atom has a distorted square-planar coordination geometry and is coordinated to the two nitrogen atoms and one oxygen atom from the tridentate ligand and one halide atom. Dehydrogenation of the chelate tridentate ligand (Lb) in the presence of oxygen afforded the corresponding nickel complexes [(Lb*)NiX] (X = Br, 6; X = I, 7). X-ray analysis showed that in these complexes the two bridged benzylic carbon atoms of (Lb)– were oxidized and a cis-stilbene moiety, which includes a C=C double bond (1.205–1.268 A) was formed. These nickel complexes with such trans-1,2-diphenylethylene bridged tridentate ligands proved to be active catalysts for ethylene oligomerization in the presence of methylaluminoxane (MAO) and produced butene and hexene with catalytic activities of 0.49 × 105–3.25 × 105 g mol–1 Ni h–1 at 30 °C, under 20 bar of ethylene, and with an MAO/Ni ratio of 250. They were also active catalysts for the homopolymerization of norbornene and styrene and displayed activities of up to 1.89 × 105 and 7.36 × 105 g mol–1 Ni h–1, respectively.

A new mechanism for the origin of multiple skeletal isomers observed in the cationic dimerization of 1-decene is proposed, and products that should form based on this mechanism are predicted. A protonated cyclopropyl intermediate appeared to form directly from combination of 2-decyl carbocation with 1-decene; formation of this intermediate did not appear to occur via ring closure of a branched secondary carbocation. The authors propose that rapid, repeated isomerizations of the protonated cyclopropyl intermediates lead to multiple skeletal isomers in decene dimers. The proposed mechanism can account for structures previously identified in mixtures of decene dimers and butene dimers. Copyright © 2012 John Wiley & Sons, Ltd.

One polypropylene (PP) was mixed with two ethylene butene copolymers (EBM). EBM1 had 12.5 mol % of butene and was immiscible with the PP. EBM2 had 51.6 mol % of butene and was miscible with the PP. The dispersed PP in EBM1 showed fractionalized crystallization behavior with a crystallization temperature at around 45°C and a much slower isothermal crystallization rate comparing to the neat PP. The PP did not exhibit fractionalized crystallization behavior in EBM2. EBM1 did not decrease both the crystallization and melting temperatures of the continuous PP. However, EBM2 could decrease both the two temperatures. It was found that EBM2 could largely suppress the epitaxial lamellar branching of the PP. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Summary: The micro-structure evolution of isotactic polypropylene-1-butene (iPPBu) and polypropylene-ethylene (iPPEt) random copolymers with 4 mol% of 1-butene and ethylene was respectively investigated by differential scanning calorimetry (DSC) and in-situ small angle X-ray scattering (SAXS) techniques during heating process. The signal of melting enthalpy of iPPBu disappears a little earlier than that of iPPEt, which keeps consistent with the decay trend of scattering intensity during the late period of melting process. However, the SAXS data further show that the crystal thickness of iPPBu is a little larger than that of iPPEt during heating process. It is suggested that the melting behaviors of such copolymers depend on not only the lamellar thickness but also the crystal stability.

Grafting of maleic anhydride (MAH) onto isotactic poly butene-1 (iPB-1) was carried out by thermal decomposition of dicumyl peroxide (DCP) using electron-donating monomer styrene (St), and were carried out in the molten state in a twin-screw extruder according to an experimental design in which the content of MAH and St were varied. The calibration curve was constructed from FTIR measurements and titration which can obtain the absolute amounts of grafted MAH according to FTIR data. The proposed mechanism was that when St is added to the iPB-1/MAH/peroxide grafting system, St reacted first with MAH to form a charge-transfer complex (CTC). Then CTC react (or copolymerize) with macroradicals. The grafting of MAH onto iPB-1 (iPB-1-MAH) accelerated crystalline transformation rate of form II to I. The contact angle decreased with the increase of grafting degree, which indicated that surface polarity increased. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

The morphology and mechanical properties of foams made out of a series of ethylene-α-olefin copolymers having well-characterized rheological properties were investigated. A compression foaming molding technique was implemented, using azodicarbonamide as the blowing agent. The polymers differed in the amount of comonomer contained (resulting in a range of densities), type of comonomer (octene vs. butene) and molecular weight, resulting in variable thermal properties and different rheological responses under shear and extensional flow. The results showed that the majority of the octene-based copolymers with comparable rheological properties had similar foam morphology. A distinct behaviour was observed for the butene-based copolymer, as well as the octene-containing one having the lowest density and lowest melting/crystallization points. The poor foamability of these grades was attributed to their differences in extensional and thermal properties, respectively. Increasing density resulted in a higher secant modulus of the foamed samples. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

Gas-phase reactions of ozone with two butenes (1-butene and isobutene) and two methyl-substituted butenes (2-methyl-1-butene and 3-methyl-1-butene) have been studied in an indoor chamber at 295–351 K. The O3 concentrations were monitored by Model 49C-Ozone analyzer. The butene concentrations were measured by gas chromatography–flame ionization detector. The Arrhenius expressions of k=3.50×10−15e(−1756±84)/T cm3 molecule−1 s−1, k=3.39×10−15e(−1697±52)/T cm3 molecule−1 s−1, k=6.18×10−15e−(1822±80)/T cm3 molecule−1 s−1, and k=7.24×10−14e−(2741±139)/T cm3 molecule−1 s−1 were obtained for the ozonolysis reactions of 1-butene, isobutene, 2-methyl-1-butene, and 3-methyl-1-butene, respectively. Both the reaction rate constant and activation energy obtained in this work are in good agreement with those reported by using different techniques in the literature. © 2011 Wiley Peiodicals, Inc. Int J Chem Kinet 43: 238–246, 2011

In the present work, crosslinked polyethylene (PEX) was obtained by adding dicumyl peroxide (DCP) to polyethylene. High-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) were used as starting polymers, synthesized by Ziegler-Natta or metallocene catalysts. Also, the effect of the comonomer type (butene or hexane) in the LLDPE was investigated. Materials were processed with increasing amounts of dicumyl peroxide (DCP). Samples were pressed with suitable amounts of these components. The efficiency of the crosslinking reaction was evaluated by gel content and thermal properties, and the melting temperature and degree of crystallinity were evaluated using differential scanning calorimetry (DSC). The microstructure of the starting polyethylene was correlated with the effectiveness of crosslinking and the resultant thermal and mechanical properties of the PEX. A new crosslinking coagent was also evaluated, along with the resistance of PEX samples in oil.

Nascent form of random copolymers of propylene with ethylene, 1 -butene, 1-hexene, 1-octene, and 4-methyl-1-pentene was studied by Raman spectroscopy. The most significant spectral alterations with a change in propylene content were observed in two lines at 8 09 and 8 41 cm -1 . The first line corresponds to vibrations of polypropylene helical chains in the crystalline phase, while the second one is associated with vibrations of polypropylene helical chains having isomeric defects. Raman data confirm that conformational composition and phase state of copolymer macromolecules strongly depend on the comonomer content as well as on the size of the comonomer units.

Cyclopropanecarbaldehyde has been photolyzed in the gas phase with light of 313 nm and 254 nm in the presence of cis-2-butene. With increasing total pressure the quantum yields of the gaseous products, carbon monoxide, ethene, propene and cyclopropane, decrease. The photolysis is accompanied by isomerization of cis-2-butene to trans-2-butene, due to the transfer of triplet energy from the aldehyde to the olefin. The quantum yield of the 2-butene triplet, OBT, increases with increasing concentration of added cis-2-butene. At a temperature of 50°, OBT is about proportional to the concentration of cis-2-butene. At a temperature of 150°, however, OBT very quickly reaches a constant value which is much lower for the photolysis with light of 313 nm (OBT ∼ 0.05) than for that with light of 254 nm (OBT ∼ 0.25).

Water-soluble palladium complexes cis-[Pd(L)(OAc)2] (1–8) (L represents a diphosphine ligands of the general formula CH2(CH2PR2)2, where for a: R (CH2)6OH; b–g: R (CH2)nP(O)(OEt)2, n = 2–6 and n = 8; h: R (CH2)3NH2) have been employed, after activation with a large excess of HBF4, for emulsion polymerization of alkenes (propene, butene, and their equimolar mixtures) with carbon monoxide. Aliphatic polyketone lattices with a high solid content (21%), high molecular weight (6.3 × 104 g mol−1), and narrow polydispersities (Mw/Mn ≈ 2) were isolated. The catalytic activity of the dicationic palladium (II) based catalysts, C1–C8 is highly dependent on the length of the alkyl chain of the ligand. Catalyst 3 proved to be highly active for propene/CO copolymers, whereas 6 is active for butene/CO and propene/CO-butene/CO systems. The presence of methyl β-cyclodextrin, as a phase-transfer agent, and undecenoic acid, as an emulsifier, increase the molar mass and the stability of the polyketones and finally the activity of the catalyst. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6715–6725, 2009

The transient temporal analysis of products (TAP) pulse method has been applied to investigate the isomerization of n-butane on sulfated zirconias at very low pressure. By combining these results with findings from XRD, XPS, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), temperature-programmed desorption (TPD), and catalytic studies at atmospheric pressure, a wide range of pressure conditions can be accessed to study the influence of surface sulfate groups on the isomerization activity and the mechanism of this reaction. The catalytic activity of powder catalysts has been correlated to the surface site density of sulfates, with pyrosulfate structures playing a major role in the initiation of the reaction. The complex interplay between sulfate-free and sulfate-covered zirconia surfaces for the adsorption of alkanes has been investigated in detail, with TAP pulse experiments showing a monomolecular reaction pathway at low n-butane partial pressures. Moreover, TAP pulse experiments have allowed detection of the reaction products of this initiation process, including butene and water, and have shown their influence on the deactivation of sulfated zirconias. Heats of adsorption have been calculated from the TAP pulse experiments.

Several N-functionalized bis(phosphanyl)amine ligands respectively containing benzyl, furfuryl, thiophene-2-methyl, thiophene-2-ethyl, and 2-picolyl groups (1a–e) were synthesized and characterized. The ligands reacted with (DME)NiBr2 in CH2Cl2 to give their corresponding nickel complexes [Ph2PN(R)PPh2NiBr2] [R = CH2C6H5 (2a), CH2C4H3O (2b), CH2C4H3S (2c), CH2C5H4N (2d), and CH2CH2C4H3S (2e)]. The structures of these complexes were established by single-crystal X-ray crystallography. All these nickel complexes were highly active towards ethylene oligomerization in the presence of methylaluminoxane or Et2AlCl, producing a high content of butene (C4). Especially for 2e, which contains a thiophene-2-ethyl pendant group, the oligomerization products obtained at –40 °C contained 95.9 mol-% C4 fraction with 100 mol-% 1-butene. Over 50 °C, however, these nickel complexes underwent Friedel–Crafts alkylation of toluene with ethylene and the olefin oligomers.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

In this article, we assess the ability of common molecular descriptors issued from quantum chemistry calculations (geometrical parameters, atomic charges, isodesmic energies, polarizabilities, and descriptors from conceptual DFT) to predict the butene selectivity in the mixed (P,N)-nickel(II) catalyzed ethylene dimerization process. To this aim, 29 active species are considered, characterized by different substitution patterns on the nitrogen and phosphorus atoms. For each of them, the Gibbs energy difference between the transition states for the third ethylene insertion and for the butene elimination is computed to characterize the selectivity. Our results show that, in contrast to previously reported catalysts, the studied descriptors did not show any significant correlations with the property to predict and their integration in a multivariate analysis was not more efficient for the considered catalytic systems. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010

Thermoplastic olefins (TPOs) are an important class of material used in the automotive industry. They are blends of isotactic polypropylene (iPP) and a polyolefin impact modifier. Chlorinated polyolefin (CPO) is a polymer used as an adhesion promoter to promote the paintability of TPO. The synthesis of a coumarin dye-labeled chlorinated (21.8 wt% Cl) maleated polypropylene (CPO), HY dye-labeled MEBR (maleated ethylene-butene copolymer with 28 wt% butene), and CPO (21.8 wt% Cl) was described. They were introduced as tracers into iPP/EBR9 (ethylene-butene copolymer with 9 wt% butene), iPP/CPO, EBR9/CPO binary, and iPP/EBR9/CPO ternary blends. The annealing effect on morphologies of the blends was examined by laser scanning confocal fluorescent microscopy (LSCFM). LSCFM revealed that the annealing caused phase coarsening in iPP/CPO and iPP/EBR blends, but had no obvious effect on the morphology of EBR/CPO blends, while in iPP/EBR/CPO ternary blends, iPP and EBR formed a completely separate domain, iPP and CPO formed their own domains EBR was distributed in the CPO domains. The morphology of iPP, EBR, and CPO binary blends was further investigated by SEM. SEM images showed that EBR and CPO interpenetrated each other on the nanometer scale in EBR/CPO blends, while obvious phase separation was observed in iPP/CPO and iPP/EBR blends. Differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD) results showed that iPP and EBR, iPP and CPO crystallized respectively in binary blends, while there was a new population of crystals formed in EBR/CPO blend. Further exploration by dynamic mechanical analysis (DMA) revealed that there were two β relaxation transitions in iPP/CPO and iPP/EBR blends, and only one β relaxation transition with a small shoulder in EBR/CPO blends. Thus, we concluded that iPP/EBR and iPP/CPO blends are immiscible; the EBR/CPO blend is miscible in the melt and partially miscible in solid state, which is in agreement with the predictions based on calculations of the results by binary interaction energy density (Bij–Bc). Copyright © 2009 John Wiley & Sons, Ltd.

Olefins and diolefins are important intermediates in the petrochemical industry, and the future promises a further substantial increase in demand. Several catalysts have been formulated in the past for the abstraction of hydrogen from butenes and propylene. However, these catalysts are inefficient in the abstraction of first hydrogen from n-butane. Bismuth molybdates (β- and γ-phases) on aluminium phosphate have been found to be good catalysts for the oxidative dehydrogenation of n-butane. Optimal conditions for the yield of (butene+butadiene) have been established in the ranges of variables studied, using response surface methodology and the following ranges of experimental conditions: temperature, 400 to 500°C; W/F (catalyst to feed ratio), 0.25 to 2.5g/(mg mol/min); butane to oxygen ratio, 0.5 to 2.0mol/min; bismuth molybdate to o-AIPO4 ratio, 0 to 100mol/100 mol. A maximum yield of approximately 13% (butenes+butadiene) was obtained in the ranges of experimental variables studied.

The oxidative dehydrogenation of 1-butene to butadienes over pyrolysed polyacrylonitrile (PPAN), a novel catalyst for the process has been studied. The catalyst was found to be considerably more active than conventional dehydrogenation catalysts, and appears more stable under reaction conditions. Higher conversions and better selectivity were obtained at much reduced temperatures (from about 250°C). The Langmuir-Hinshelwood mechanism, which assumes that surface reaction between adsorbed oxygen and butene species is rate controlling, has been used to explain the experimental results.

The intermetallic pseudo-binary alloys of the general type ZrRh3-xPdx and ZrRh3-xRux (0 < × < 3) have been prepared by argon arc melting and melt quenching of the constituent elements. The alloys were powdered and employed as catalysts for (i) hydrogenation of oct-1-yne in the liquid phase at 101.32 kPa total pressure and 70°C, (ii) hydrogenation of buta-1,3-diene in the gas phase at 101.32 kPa total pressure in the temperature range 45–225°C, and (iii) hydrogenolysis of n-pentane in the gas phase at 101.32 kPa total pressure and in the temperature range 200–400°C. Activity and selectivity measurements were made with respect to (i) alkene formation for the hydrogenation reactions, and (ii) C2 + C3-alkane formation for the hydrogenolysis reaction. The activity of the alloy series appears to correlate to some degree with the electronic properties and hydrogen sorption capacity of the intermetallic alloys. Auger electron spectroscopy measurements revealed that for ZrRh3-xPdx alloys both the surface and bulk compositions were in good agreement; this behaviour is contrasted briefly with that of CeRh3-xPdx alloys which, unlike ZrRh3-x alloys, suffered significant oxygen interaction in the surface and sub-surface layers, although this did not affect Rh:Pd ratios. Catalysts that were active for hydrogenation were inactive for hydrogenolysis and vice versa. However, selectivity values for the hydrogenation reactions generally reflected the behaviour of the predominant noble transition metal. Again, the behaviour of ZrRh3-xPdx and CeRh3-x alloys is contrasted, since the latter were more selective for butene formation from buta-1,3-diene, and attributed to the oxygen Contamination of the surface. Further more, the selectivity of both ZrPd and CePd, for 1-octyne and butu-l j-dene hydrogenation was significantly greater than that of palladium by virtue of the fact that the intermetallics were found to be largely inactive for alkene hydrogenation.