Nanoporous PdNi/C Electrocatalyst Prepared by Dealloying High‐Ni‐content PdNi Alloy for Formic Acid Oxidation

To improve the electrochemical performance of Pd‐based catalysts for formic acid oxidation, a carbon supported nanoporous PdNi catalyst is prepared by dealloying high‐Ni‐content PdNi alloy nanoparticles in acid solution. The structure of nanoporous PdNi/C catalyst is characterized by X‐ray diffraction, transmission electron microscopy and X‐ray photoelectron spectroscopy. The electrocatalytic results show that the activity of the nanoporous PdNi/C catalyst is higher than that of nonporous Pd/C catalyst. The results demonstrate that the carbon‐supported nanoporous PdNi catalyst has a potential for application in direct formic acid fuel cells.     

Palladium‐Iminodiacetic Acid Immobilized on pH‐Responsive Polymeric Microspheres: Efficient Quasi‐Homogeneous Catalyst for Suzuki and Heck Reactions in Aqueous Solution

The pH‐responsive core‐shell microspheres of poly(styrene‐co‐methylacrylic acid) (PS‐co‐PMAA) containing a polystyrene (PS) core and a poly(methylacrylic acid) (PMAA) shell are synthesized by one‐stage soap‐free copolymerization and the catalyst system palladium‐iminodiacetic acid (IDA‐Pd) is immobilized on the outer shell‐layer of the core‐shell microspheres to form the quasi‐homogeneous and easily accessible catalyst PS‐co‐PMAA‐IDA‐Pd. This quasi‐homogeneous PS‐co‐PMAA‐IDA‐Pd catalyst is highly dispersed in the reaction medium just like a homogeneous one and can be separated like a heterogeneous catalyst by adjusting the pH of the reaction medium. Suzuki reactions employing the quasi‐homogeneous PS‐co‐PMAA‐IDA‐Pd catalyst are efficiently performed in water as the sole solvent under mild conditions such as room temperature. The PS‐co‐PMAA‐IDA‐Pd catalyst is also used in Heck reactions of a wide range of aryl halides with styrene and proves to be efficient in aqueous solution. The PS‐co‐PMAA‐IDA‐Pd catalyst has a low leaching loss and can be reused at least 4 times without loss of activity.     

Efficient Acylation of Anisole over Hierarchical Porous ZSM‐5 Structure

Friedel‐Crafts acylation is one of the most important methods to prepare aromatic ketones which are used in manufacturing fine and speciality chemicals, as well as pharmaceuticals. Herein, we report an efficient and convenient procedure for the acylation of anisole with acetic anhydride, using a hierarchical porous ZSM‐5 catalyst. The hierarchical porous ZSM‐5 catalyst was synthesized using styrene butadiene rubber (SBR) as macroporous template. The catalysts were characterized for their structural features by using XRD, SEM, and FT‐IR analyses. The effect of temperature, molar ratio, and catalyst weight on the acylation of anisole was studied in detail. The reaction parameters such as anisole‐to‐acetic anhydride mole ratio, catalyst weight, and reaction temperature were optimized as 5:1, 0.2 g, and 70 °C, respectively. The method described here is environmentally benign and replaces the conventional catalyst by a highly active and reusable catalyst.     

Preparation of silica‐supported late transition metal catalyst and ethylene polymerization

A Correction has been published for this article in Polymer International 51(6) 2002, 561 The late transition metal catalyst 2,6‐bis[1‐(2,6‐diisopropylphenylimino)ethyl]pyridine iron(II) chloride was supported on silica. Fourier transform infrared spectroscopy, scanning electronic micrograph and X‐ray photoelectron spectroscopy measurements were utilized to examine the process of supporting catalyst on silica and investigate the possible mechanism of support. Furthermore, ethylene polymerizations with the supported catalysts were carried out in various conditions such as different reaction temperatures and Al/Fe molar ratios. The results showed that MAO first reacted with the hydroxyl of silica forming Si? O? Al bonds and then the catalyst was bridged through MAO on the surface of silica. Compared with homogeneous catalysts, the supported catalysts show some decrease in catalyst activity. However, they can show good activity at a lower Al/Fe molar ratio with MAO as co‐catalyst and give rise to higher molecular weight and melting temperature of the polymer. Better morphology of polyethylene was obtained by a supported catalyst than by its corresponding homogeneous catalyst. The late transition metal catalyst 2,6‐bis[1‐(2,6‐diisopropylphenylimino)ethyl]pyridine iron(II) chloride was supported on silica. Fourier transform infrared spectroscopy, scanning electronic micrograph and X‐ray photoelectron spectroscopy measurements were utilized to examine the process of supporting catalyst on silica and investigate the possible mechanism of support. Furthermore, ethylene polymerizations with the supported catalysts were carried out in various conditions such as different reaction temperatures and Al/Fe molar ratios. The results showed that MAO first reacted with the hydroxyl of silica forming Si? O? Al bonds and then the catalyst was bridged through MAO on the surface of silica. Compared with homogeneous catalysts, the supported catalysts show some decrease in catalyst activity. However, they can show good activity at a lower Al/Fe molar ratio with MAO as co‐catalyst and give rise to higher molecular weight and melting temperature of the polymer. Better morphology of polyethylene was obtained by a supported catalyst than by its corresponding homogeneous catalyst. © 2002 Society of Chemical Industry     

Development of a Method for Preparing a Highly Reactive and Stable,Recyclable and Environmentally Benign Organopalladium Catalyst Supported on Sulfur‐Terminated Gallium Arsenide(001): A Three‐Component Catalyst, {Pd}‐S‐GaAs(001), and its Properties

We have developed a method for preparing a recyclable and environmentally benign organopalladium catalyst for the Heck reaction supported on sulfur‐terminated gallium arsenide(001). This three‐component catalyst, {Pd}‐S‐GaAs(001), exhibited high stability and activity, furthermore, it tolerated reuse in 10 runs of the Heck reaction (average yield, 97 %) under aerobic conditions. The sulfur layer was very important to stabilize this catalyst. Only trace amounts of Pd were leached from this catalyst to the reaction mixture, as measured by ICP‐mass. The valence of immobilized Pd was zero by XPS spectrometry.     

Preparation and barrier property of poly(ethylene terephthalate)/clay nanocomposite using clay‐supported catalyst

Poly(ethylene terephthalate) (PET)/clay nanocomposite was prepared by the direct polymerization with clay‐supported catalyst. The reaction degree of catalyst against the cation exchange capacity of clay was 8 wt %. The intercalation of PET chains into the silicate layers was revealed by X‐ray diffraction studies. SEM morphology of the nanocomposite showed a good dispersion of clay‐supported catalyst, ranging from 30 to 100 nm. The intercalated and exfoliated clay‐supported catalyst in PET matrix was also observed by TEM. The improvement of O₂ permeability for PET/clay‐supported catalyst composite films over the pure PET is approximately factors of 11.3–15.6. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4875–4879, 2006     

Modeling of the propylene polymerization catalyzed by single‐/multi‐active site catalyst: A Monte Carlo study

In the present study, a model is established to describe the propylene polymerization kinetics catalyzed by the typical catalysts with single‐/multi‐active site type in a liquid phase stirred‐tank reactor using the Monte Carlo simulation method, regardless of the mass and heat diffusion effects within the polymer particles. Many kinetic data, including polypropylene yield, concentration transformation of catalyst active sites, number–average molecular weight, etc., are obtained by the model. The simulated kinetic results are found to be in agreement with the reference ones obtained in a population balance model. Furthermore, the comparisons of the kinetic data between the polymerization catalyzed by the catalyst with single‐active site type (typically silica‐supported metallocene) and the catalyst with multi‐active site type (typically MgCl₂‐supported Ziegler‐Natta catalyst) have been studied using the model. Especially, the effects of hydrogen on the polymerization are studied using the model. The studied results show that the theory of catalyst active site can be used to explain the different propylene polymerization kinetics catalyzed by the typical catalyst with single‐/multi‐active site type. In addition, the role of hydrogen in the propylene polymerization needs to be emphasized. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Post‐Plasma Catalysis for Methane Partial Oxidation to Methanol: Role of the Copper‐Promoted Iron Oxide Catalyst

Methane‐air partial oxidation to methanol over a ceramic‐supported Fe₂O₃‐CuO catalyst was investigated in a post‐plasma catalytic reactor at ambient conditions. The multicomponent catalyst exerted a better catalytic performance than the monocomponent Fe₂O₃ catalyst. Characterization of the catalysts by XPS showed that incorporation of the CuO additive to a Fe₂O₃‐based catalyst resulted in an increase of lattice oxygen in the surface of the catalyst which facilitated selective methane oxidation. Hydrogen temperature‐programmed reduction revealed that addition of the CuO promoter could improve the reduction performance of the catalyst. Moreover, this catalyst showed excellent stability and resistance against carbon deposition in the extended reactions while maintaining catalytic activity. A post‐plasma catalytic mechanism is proposed with three main pathways to methanol synthesis.     

Silica‐supported bis(imino)pyridyl iron(II) catalyst: nature of the support–catalyst interactions

Ethylene polymerizations were performed using silica‐supported 2,6‐bis[1‐(2,6‐diisopropylphenylimino) ethyl] pyridine iron(II) dichloride with methylaluminoxane (MAO) as co‐catalyst. Silica was calcined at 600, 400 and 200 °C under vacuum for 8 h. The effect of calcination temperature of silica on the polymerization activity and the properties of the polymers obtained were examined. Catalyst–support interactions were examined by both a chemical method and XPS. It was observed that upon supporting the catalyst on the surface of silica, there is an increase in the binding energy of the metal center. However, no change in the metal binding energy was observed on supporting the catalyst to silica calcined at different temperatures. Ethylene polymerizations were performed using MAO as co‐catalyst. Catalysts were also prepared by first pretreating silica with MAO, followed by addition of the Fe(II) catalyst and contacting a complex of Fe(II) catalyst–MAO with silica previously calcined at 400 °C for 8 h. The results indicate that there is no chemical bonding between the support and the catalyst. Copyright © 2006 Society of Chemical Industry     

A new post‐metallocene catalyst for alkene polymerization: copolymerization of ethylene and 1‐hexene with titanium complexes bearing N,N‐dialkylcarbamato ligands

A new type of post‐metallocene polymerization catalyst based on titanium complexes with N,N‐dialkylcarbamato ligands was used to copolymerize ethylene and 1‐hexene. These easy‐to‐synthesize and stable complexes in combination with different organoaluminium co‐catalysts produce random ethylene/1‐hexene copolymers characterized by a broad molecular weight distribution and high 1‐hexene incorporation, as confirmed by SEC, DSC and ¹³C NMR analysis. The influence of the main reaction parameters on the polymerization reactions was studied including the type of catalyst components, solvent, temperature, the ethylene partial pressure and the [Al]/[Ti] ratio in the catalyst. A higher activity and a higher 1‐hexene incorporation were achieved with AlMe₃‐depleted methylalumoxane as co‐catalyst and chlorobenzene as solvent. © 2013 Society of Chemical Industry     

Operability of an Industrial Methanol Synthesis Reactor with Mixtures of Fresh and Partially Deactivated Catalyst

Disposal of spent catalyst is a common practice in industrial methanol synthesis. However, the spent catalyst has, generally, a good level of activity and can be used if mixed with fresh catalyst. In this work the operation of an industrial methanol synthesis reactor with mixtures of fresh and partially deactivated catalyst was investigated using a one‐dimensional transient model. Analysis of the deactivation behavior of low‐pressure methanol synthesis catalyst shows there is an extremely sharp rate of deactivation in a small part of the catalyst life‐time, which is followed by a relatively slow rate of deactivation in the remaining catalyst cycle‐time. Different configurations were studied for catalyst recycling, and two limiting cases are discussed in detail in this paper, namely layered and homogeneous (mixed) bed models. In the first one, the catalyst was segregated into two alternate layers of fresh and partially deactivated catalyst, while in the second homogeneity of the catalyst bed was simulated by segregating a large number of alternate layers of fresh and partially deactivated catalyst. It was observed in both cases that when catalyst recycling is used, the process does not depart significantly from the standard operating conditions, and also that the mixed bed had less influence on the reactor performance than layered one.     

High‐Pressure High‐Temperature Transparent Fixed‐Bed Reactor for Operando Gas‐Liquid Reaction Follow‐up

A 3‐MPa, 350 °C fixed‐bed reactor was designed to follow‐up gas‐liquid‐solid reactions on a millimetric size heterogeneous catalyst with Raman spectroscopy. The transparent reactor is a quartz cylinder enclosed in a Joule effect heated stainless‐steel tube. A methodology to determine how to focus the microscope for liquid and solid phase characterization is presented. The setup was validated by performing diesel hydrodesulfurization on a CoMo/alumina extrudate catalyst with a conversion very close to expected values along with the acquisition of Raman spectra of the solid catalyst showing an evolution of the catalyst phase during sulfidation.     

Bis (2‐mercapto‐ethyl) amine modification of macroporous sulfonic resin catalyst in bisphenol‐a synthesis

A novel catalyst for bisphenol‐A synthesis was prepared by bis (2‐mercapto‐ethyl) amine adsorbed on macroporous sulfonic resin through neutralization reaction. The physicochemical properties of two resin catalysts before and after bis (2‐mercapto‐ethyl) amine absorption were compared by scanning electron microscope and nitrogen adsorption. The kinetic of the new catalyst preparation process was studied and it was found that this is a chemical adsorption and endothermic process. The adsorption rate is mainly controlled by the intraparticle diffusion, affected by boundary layer diffusion and chemical reaction as well. The thermodynamic activation parameters were calculated. Compared with unmodified catalyst, the modified resin catalyst showed higher selectivity and acetone conversion in the continuous bisphenol‐A synthesis process. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3816–3823, 2013     

Attapulgite‐supported aluminum oxide hydroxide catalyst for synthesis of poly(ethylene terephthalate)

A novel nanocomposite catalyst was prepared from immobilization of aluminum oxide hydroxide onto the attapulgite. Characterizations with scanning electron microscopy (SEM) and wide angle X‐ray diffraction (XRD) of the as‐prepared catalyst revealed that AlO(OH) nanoparticles were distributed on the attapulgite. Thermogravimetric analysis‐infrared spectrometry (TGA‐IR) of the mixture prepared by mixing of bishydroxy ethylene terephthalate (BHET) and the catalyst indicated that attapulgite‐supported aluminum oxide hydroxide catalyst can catalyze BHET polycondensation under the applied conditions. A kinetic model for determining the activation energy has been applied to evaluate the catalyst activity. The catalyst activity was examined through comparative experiments, and the results showed that the new catalyst exhibited higher activity for BHET polycondensation under identical reaction conditions, and the viscosity‐average molecular weight of poly(ethylene terephthalate) (PET) product obtained was increased about 2000 g/mol. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis of allyl‐ended hyperbranched organic silicone resin by halloysite‐supported platinum catalyst

A novel allyl‐ended hyperbranched organic silicone resin (AHSR) was prepared successfully by hydrosilylation between phenyltriallylsilane and 1,1,3,3‐tetramethyl disiloxane with halloysite‐supported platinum (Pt–halloysite) as the catalyst. The chemical structure of the AHSR was characterized by ¹H‐NMR and Fourier transform infrared spectroscopy, and its molecular weight was determined by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. The Pt–halloysite catalyst was prepared from chloroplatinic acid and halloysite by the simple wet impregnation method. The transmission electron micrographs of the catalyst showed that the platinum dispersed homogeneously into the halloysite nanotubes. Compared with the traditional homogeneous Speier and Karstedt catalysts, our heterogeneous Pt–halloysite catalyst demonstrated a higher catalytic activity, which was confirmed by IR monitoring of the attenuation of the Si? H stretching band. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Fe(2‐EHA)3/Al(i‐Bu)3/hydrogen phosphite catalyst for preparing syndiotactic 1,2‐polybutadiene

Polymerizing 1,3‐butadiene into syndiotactic 1,2‐polybutadiene with an iron(III) catalyst system has been investigated. Activity of the catalyst was affected by the type of cocatalyst alkylaluminum and the phosphorus compound as an electron donor, molar ratio of catalyst components, and their aging sequence and aging time of the catalyst. The microstructure and configuration of the polymer was decided by the catalyst components, the higher [Al]/[Fe] molar ratio tending to yield syndiotactic 1,2‐polybutadiene, while the higher [P]/[Fe] molar ratio favors the formation of amorphous 1,2‐polybutadiene. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4265–4269, 2006     

Heterogeneous Catalytic Reactor Design with Non‐Uniform Catalyst Considering Shell‐Progressive Poisoning Behavior

A novel methodology has been developed to design an optimum heterogeneous catalytic reactor, by considering non‐uniform catalyst pellet under shell‐progressive catalyst deactivation. Various types of non‐uniform catalyst pellets are modelled in combination with reactor design. For example, typical non‐uniform catalyst pellets such as egg‐yolk, egg‐shell and middle‐peak distribution are developed as well as step‐type distribution. A progressive poisoning behavior is included to the model to produce correct effectiveness factor from non‐uniform catalyst pellet. As opposed to numerical experiment with limited type of kinetic application to the model in the past, this paper shows a new methodology to include any types of kinetic reactions for the modeling of the reactor with non‐uniform catalyst pellet and shell‐progressive poisoning. For an optimum reactor design, reactor and catalyst variables are considered at the same time. For example, active layer thickness and location inside pellet are optimised together with reactor temperature for the maximisation of the reactor performance. Furthermore, the temperature control strategy over the reactor operation period is added to the optimization, which extends the model to three dimensions. A computational burden has been a major concern for the optimization, and innovative methodology is adopted. Application of profile based synthesis with the combination of SA (Simulated Annealing) and SQP (Successive Quadratic Programming) allows more efficient computation not only at steady state but also in dynamic status over the catalyst lifetime. A Benzene hydrogenation reaction in an industry scale fixed‐bed reactor is used as a case study for illustration.     

Chiral Primary Amine Tagged to Ionic Group as Reusable Organocatalyst for Asymmetric Michael Reactions of C‐Nucleophiles with α,β‐Unsaturated Ketones

The first primary amine‐derived organocatalyst modified with an ionic group for asymmetric Michael reactions of C‐nucleophiles with α,β‐unsaturated ketones was synthesized. In the presence of this catalyst and an acidic co‐catalyst (AcOH), hydroxycoumarin and its sulfur‐containing analogue reacted with benzylideneacetone derivatives or cyclohexenone to afford the corresponding Michael adducts in high yields (up to 97%) and with reasonable enantioselectivity (up to 80%). The catalyst could be easily recovered and efficiently reused three times, afterwards, its activity and stereodifferentiating ability gradually declined. The analysis of recovered catalyst samples by ESI‐MS allowed us to detect undesirable side reactions that poisoned the catalyst, and propose an approach for its reactivation.     

Characteristics of diether‐ and phthalate‐based Ziegler‐Natta catalysts for copolymerization of propylene and ethylene and terpolymerization of propylene,ethylene, and 1‐butene

Copolymerization of propylene and ethylene and terpolymerization of propylene, ethylene, and 1‐butene were carried out to compare the characteristics of diether‐ and phthalate‐based Ziegler‐Natta catalysts in a reaction system of pilot scale. The ethylene incorporation with the diether‐based catalyst was higher but the 1‐butene incorporation was lower compared with those of the phthalate‐based catalyst. In the case of copolymers from the diether‐based catalyst, melting behavior, determined through differential scanning calorimetry (DSC), showed a distinct shoulder peak and lots of nuclei were formed during crystallization. The diether‐based catalyst led to polymers having blockier ethylene sequences compared with those of the phthalate‐based catalyst; the highly crystallizable fraction (HIS) containing blockier ethylene sequences was produced with the diether‐based catalyst. These results seem to be the result of regio‐irregular characteristics of the diether‐based catalyst. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 851‐859, 2013     

Gold‐Catalyzed Cyclizations: A Comparative Study of ortho,ortho′‐Substituted KITPHOS Monophosphines with their Biaryl Monophosphine Counterpart SPHOS

Electrophilic gold(I) triflimide (trifluoromethanesulfonimide) complexes of electron‐rich ortho,ortho′‐disubstituted KITPHOS (11‐dicyclohexylphosphino‐12‐phenyl‐9,10‐ethenoanthracene) monophosphines are efficient catalysts for intramolecular cycloisomerizations that afford phenols, 3‐acylindenes and methylene‐oxazolines; comparative catalyst testing showed that these catalysts either competed with or outperformed that based on SPHOS [2‐(2′,6′‐dimethoxybiphenyl)dicyclohexylphosphine]. An electron‐rich biarylmonophosphine containing a single ortho‐methoxy substituent, prepared by rhodium‐catalyzed [2+2+2] cycloaddition between a 1‐alkynyl(dicyclohexylphosphine) oxide and 1,7‐octadiyne, also formed a highly efficient catalyst for the same transformations. Monitoring of comparative catalyst testing between a KITPHOS‐based gold(I) triflimide complex containing a coordinated tetrahydrothiophene and its counterpart coordinated solely by the triflimide anion revealed that the former is an order of magnitude less efficient than the latter, confirming that tetrahydrothiophene can be an effective catalyst inhibitor.