Search

Industrial production of H2O2 requires lots of energy and causes environmental pollution. Moreover, in subsequent applications, much economic loss could be produced during the transportation process of H2O2 and its dilution process. Therefore, it is highly desirable for in situ application of H2O2. In recent years, catalytic synthesis of H2O2, e. g., direct catalytic synthesis, electrocatalytic synthesis, and photocatalytic synthesis, has attracted more and more attention because the continuous and low‐concentration H2O2 produced by catalytic synthesis can be directly used for the oxidation of organic compounds, effectively avoiding the shortcomings of the current industrial route. Here, we briefly reviewed the latest processes for the catalytic production of H2O2 via various routes. On this basis, we summarized and discussed the in situ application of H2O2 in typical organic conversion reactions, including the ammoximation of ketones, the oxidation of alcohols, the oxidation of C−H bonds, and the oxidation of olefins. Some in situ coupling reactions have shown excellent performance with high conversion and selectivity, and the economic cost has been significantly reduced. Finally, the shortcomings of the in situ utilization of H2O2 in coupling reactions were analyzed, and some strategies for promoting the efficiency of the H2O2 application in organic synthesis were proposed. [ABSTRACT FROM AUTHOR]

Mesophase pitch is usually prepared by radical polymerization or catalytic polymerization from coal tar, petroleum, and aromatic compounds, and the catalytic synthesis of mesophase pitch from pure aromatic compounds is more controllable in the preparation of high-quality mesophase pitch. However, the corrosive and highly toxic nature of the catalyst has limited the further development of this method. In this study, mesophase pitch was synthetized using ethylene tar and naphthalene as raw materials and boron trifluoride diethyl etherate as a catalyst. The effect of the catalytic reaction on the structure and properties of the mesophase pitch was investigated. The results show that naphthalene plays an important role in the mesophase content and reaction pressure (from above 6 MPa to 2.35 MPa). Mesophase pitch with fine-flow texture can be prepared by introducing more methylene groups, naphthenic structures, and aliphatic hydrocarbons during synthesis. Carbon fibers prepared from mesophase pitch show a split structure, and the thermal conductivity is 730 W/(m·K). This work provides theoretical support for lower toxicity and causticity and for reaction-controlled technology for the synthesis of high-purity mesophase pitch. [ABSTRACT FROM AUTHOR]

Mesophase pitch is usually prepared by radical polymerization or catalytic polymerization from coal tar, petroleum, and aromatic compounds, and the catalytic synthesis of mesophase pitch from pure aromatic compounds is more controllable in the preparation of high-quality mesophase pitch. However, the corrosive and highly toxic nature of the catalyst has limited the further development of this method. In this study, mesophase pitch was synthetized using ethylene tar and naphthalene as raw materials and boron trifluoride diethyl etherate as a catalyst. The effect of the catalytic reaction on the structure and properties of the mesophase pitch was investigated. The results show that naphthalene plays an important role in the mesophase content and reaction pressure (from above 6 MPa to 2.35 MPa). Mesophase pitch with fine-flow texture can be prepared by introducing more methylene groups, naphthenic structures, and aliphatic hydrocarbons during synthesis. Carbon fibers prepared from mesophase pitch show a split structure, and the thermal conductivity is 730 W/(m·K). This work provides theoretical support for lower toxicity and causticity and for reaction-controlled technology for the synthesis of high-purity mesophase pitch.

Diphenyl carbonate (DPC) is one of the versatile carbonates, and is often used for the production of polycarbonates. In recent years, the catalytic synthesis of DPC has become an important topic but the development of a highly active metal-free catalyst is a great challenge. Herein, a series of ionic liquids-SBA-15 hybrid catalysts with different functional groups have been developed for the synthesis of DPC under solvent-free condition, which are effective and clean instead of the metal-containing catalysts. It is found that in the presence of [SBA-15-IL-OH]Br catalyst, methyl phenyl carbonate (MPC) conversion of 80.5% along with 99.6% DPC selectivity is achieved, the TOF value is thrice higher than the best value reported by using transition metal-based catalysts. Moreover, the catalyst displays remarkable stability and recyclability. This work provides a new idea to design and prepare eco-friendly catalysts in a broad range of applications for the green synthesis of carbonates.

It is presented that the activated carbon was carboxylated with hydrogen peroxide and then acylated with 2-methylimidazole to prepare the porous carbon support with a surface imidazolated modification. Through the adsorption of phosphotungstic acid on the fundamental site of an imidazolyl group and then adjusting the acid strength with the ammonia molecule, a catalytic carbon material immobilized with ammonium phosphotungstate (AC-COIMO-NH4PW) was obtained, which was used to catalyze a one-pot reaction of convenient α-pinene and hydrogen peroxide to sobrerol. The bifunctional active site originated from the dual property of ammonium phosphotungstate, as the oxidant and acid presenting a cooperatively catalytic performance, which effectively catalyzes the tandem epoxidation–isomerization–hydration of α-pinene to sobrerol, in which the solvent effect of catalysis simultaneously exists. The sobrerol selectivity was significantly improved after the acid strength weakening by ammonia. Monomolecular chemical bonding and anchoring of ammonium phosphotungstate at the basic site prevented the loss of the active catalytic species, and the recovered catalyst showed excellent catalytic stability in reuse. Using acetonitrile as the solvent at 40 °C for 4 h, the conversion of α-pinene could reach 90.6%, and the selectivity of sobrerol was 40.5%. The results of five cycles show that the catalyst presents excellent stability due to the tight immobilization of ammonium phosphotungstate bonding on the imidazolized activated carbon, based on which a catalytic-cycle mechanism is proposed for the tandem reaction. [ABSTRACT FROM AUTHOR]

It is presented that the activated carbon was carboxylated with hydrogen peroxide and then acylated with 2-methylimidazole to prepare the porous carbon support with a surface imidazolated modification. Through the adsorption of phosphotungstic acid on the fundamental site of an imidazolyl group and then adjusting the acid strength with the ammonia molecule, a catalytic carbon material immobilized with ammonium phosphotungstate (AC-COIMO-NH4PW) was obtained, which was used to catalyze a one-pot reaction of convenient α-pinene and hydrogen peroxide to sobrerol. The bifunctional active site originated from the dual property of ammonium phosphotungstate, as the oxidant and acid presenting a cooperatively catalytic performance, which effectively catalyzes the tandem epoxidation–isomerization–hydration of α-pinene to sobrerol, in which the solvent effect of catalysis simultaneously exists. The sobrerol selectivity was significantly improved after the acid strength weakening by ammonia. Monomolecular chemical bonding and anchoring of ammonium phosphotungstate at the basic site prevented the loss of the active catalytic species, and the recovered catalyst showed excellent catalytic stability in reuse. Using acetonitrile as the solvent at 40 °C for 4 h, the conversion of α-pinene could reach 90.6%, and the selectivity of sobrerol was 40.5%. The results of five cycles show that the catalyst presents excellent stability due to the tight immobilization of ammonium phosphotungstate bonding on the imidazolized activated carbon, based on which a catalytic-cycle mechanism is proposed for the tandem reaction.

[Display omitted] An innovative and easy multicomponent synthesis of important biologically active molecules, 5-unsubstituted 3,4-dihydropyrimidine-2-ones, via the Biginelli reaction between aromatic aldehydes, acetophenone derivatives and urea catalyzed by a novel bimetallic phosphate catalyst CoCa 3 (HPO 4)(PO 4) 2 (OH) was developed. The catalyst support, prepared by the coprecipitation method using phosphoric acid, calcium nitrate, and cobalt nitrate, was characterized for its chemical structure and composition through various spectroscopy analyses such as X-ray diffraction (XRD), infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and elemental analysis ICP-MS. The developed catalyst showed high efficiency in organic synthesis, allowing us to prepare various 3,4-dihydropyrimidine-2-ones derivatives in excellent yields of up to 97% under mild reaction conditions and in a short reaction time of 10 min. This new approach offers many advantages over conventional systems, notably in terms of simplicity, ease of handling, production cost and the possibility of reusing the catalyst up to seven times. This work provides a novel alternative method for the synthesis of 5-unsubstituted 3,4-dihydropyrimidine-2-ones derivatives. [ABSTRACT FROM AUTHOR]

The magnetic biocompatible rod‐like ZnS/CuFe2O4/agar organometallic hybrid catalyst was designed and prepared based on a natural macromolecule (agar) through a green and convenient method using inexpensive, nontoxic, and easily available substances. Then, the as‐prepared catalyst was characterized by several techniques such as Fourier transform‐infrared spectroscopy, energy‐dispersive X‐ray analysis, scanning electron microscopy image, transmission electron microscopy, vibrating sample magnetometry curve, X‐ray diffraction pattern, and thermogravimetric analysis. Eventually, the catalytic application of the ZnS/CuFe2O4/agar nanobiocomposite was assessed in sequential Knoevenagel condensation–Michael addition reaction of dimedone, malononitrile, and different substituted aromatic aldehydes for the synthesis of 2‐amino‐tetrahydro‐4H‐chromene‐3‐carbonitrile derivatives. Some notable strengths of this environmentally benign catalyst include simplicity of catalyst preparation and separation, affording desired products with satisfactory yields (81%–97%) in very short reaction times (3–18 min), and with no need for complicated work‐up processes. Experimental tests showed that the catalyst can be successfully reused after five sequential runs without significant reduction in its catalytic efficiency. [ABSTRACT FROM AUTHOR]

In the recent past, society has become increasingly aware of the environmental impact of political and corporate action. Hence, several industrial sectors are currently undergoing a transition to more sustainable products and processes. Sustainable production processes for C2‐C4 alcohols can help to decrease the environmental impacts of large downstream markets such as fuels and polymers. However, a reliable and consistent framework is needed for companies to further develop and commercialize these processes. Furthermore, standardized procedures for determining the sustainability of a process are essential in evaluating the environmental benefits. [ABSTRACT FROM AUTHOR]

The oxidation-precipitation method was used for the synthesis of Fe3O4/AC. The characterization of the catalyst was accomplished by XRD, FT-IR, FE-SEM, BET, and VSM techniques. The obtained results indicated that magnetite nanoparticles were successfully prepared with cubic spinel structures and uniform distribution on the surface of activated carbon by the oxidation-precipitation method. The effect of operating parameters was evaluated to determine the optimum operating condition for the electro-Fenton (EF) removal of catechol as a phenolic pollutant model. At the optimum operating conditions (pH 3, Fe3O4/AC: 0.9 g L−1, Catechol: 8.0 × 10−4 mol L−1 at I: 120 mA), the catechol and COD removal reached 98.2 and 76.1% in 120 min, respectively. Only 2.1% of ferrous and 3.44% of ferric ions were leached into the solution. Regarding the results from utilization of oxidant scavengers (isopropanol and BQ), it can be inferred that hydroxyl radical (responsible for 57% catechol removal) and superoxide anion radical (responsible for 40% catechol removal) is the main oxidants in acidic (pH 3) and basic (pH 10) conditions, respectively. The kinetics of EF removal of catechol was studied and the rate constant for the pseudo-first-order kinetic model was found to be 3.37 × 10−2min−1 (R2 = 0.9924). The GC-MS analysis was carried out to detect the intermediate products and a possible degradation mechanism was proposed. The reusability of Fe3O4/AC was examined for six cycles. It can be concluded that Fe3O4/AC is an applicable ultimate catalyst for EF removal of organic pollutants. [ABSTRACT FROM AUTHOR]

The characteristics of silicon-oxide layers deposited by various technological methods are compared. It is shown that the catalytic method for obtaining silicon-oxide layers by molecular layering has a number of advantages. The main advantages are a low growth temperature, high-quality interface with a silicon substrate, and high growth rate of films. Studies by cathodoluminescence made it possible to evaluate the structural quality of silicon-oxide layers produced by molecular layering and confirmed the potential of this method in obtaining high-quality silicon-oxide films for broad practical application. [ABSTRACT FROM AUTHOR]

Copyright of Iraqi Journal of Chemical & Petroleum Engineering is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Experimental studies of ammonia oxyethylation in a flow microchannel reactor are performed in broad ranges of temperatures (70–180°C) and residence times (0.47–3.3 min). The main products of the reaction between ethylene oxide (EO) and ammonia are monoethanolamine (MEA), diethanolamine (DEA), and target triethanolamine (TEA). It is shown that EO conversion grows along with residence time τ and reaches 90% at τ = 3.3 min. The highest selectivity toward MEA and DEA is observed at a temperature of 70°C and τ = 3.3 min. High selectivity toward TEA (84%) is achieved at short τ (0.47 min) and the maximum temperature (180°C). The TEA yield grows along with temperature and the residence time to reach 62% at τ = 3.3 min and temperatures of 155–180°C. Mathematical modeling of the ammonia oxyethylation process allows the kinetic constants of individual stages to be calculated. Differences between the obtained kinetic parameters and the literature data, due probably to using a microchannel reactor that ensures high parameters of heat and mass transfer instead of a traditional bulk triethanolamine synthesis reactor, are revealed. [ABSTRACT FROM AUTHOR]

In-depth exergy analysis of three conceptual biomass-mixed alcohol systems using syngas platform has been studied, according to the distribution strategy of synthesis tail gas and syngas. The system configurations are base case, cascade case and parallel case. The results show that higher alcohol yield (C 2+ OH) is highest in base case, which is a catalytic synthesis process with synthesis tail gas recycling. Yet its exergy efficiency is lower than that of 43.8% in the hybrid conversion configuration of cascade case, of which synthesis tail gas is recycled to an additional subsystem for gas fermentation. And it has increased bioconversion of CO X components (CO and CO 2) in tail gas for ethanol production under moderate bioreaction condition and biomass carbon utilization ratio of 38.8% is obtained in cascade case. With the detailed exergy analysis at the levels of system, subsystem, and operation component, it highlights that the subsystems of gasification and steam & power generation contribute above 70% of total system exergy destruction, mainly from gasifier and combustor. The results of this study provide a further understanding towards bio-mixed alcohol production configuration to improve its thermodynamic performance as exergy efficiency via the hybrid conversion processes of catalytic synthesis and metabolic fermentation pathway. [Display omitted] • Exergy analysis of three bio-mixed alcohol system using syngas platform is studied. • Hybrid cascade process as synthesis and tail gas fermentation shows better results. • Maximum yield of mixed alcohol can be obtained via high conversion of CO X in syngas. • Exergy efficiency of cascade case is 43.8% with alcohol yield of 0.329 t/t biomass. • Gasification and steam & power generation contribute above 70% of irreversibility. [ABSTRACT FROM AUTHOR]

We use a computational fluid dynamics model coupled with a particle dynamics model to simulate how catalyst nanoparticles nucleate, grow and evaporate over the length of a floating catalyst reactor. We focus on the influence of the flowrate in the reactor and the ferrocene mass fraction on the production of the catalyst nanoparticles. In the downstream region of the reactor, where the majority of CNT growth occurs, we find that, as either the flowrate or the ferrocene mass fraction increases, the particle mass fraction profile changes, with the mass fraction peak shifting away from the centreline. This displacement away from the centreline of the mass fraction peak may explain why the CNTs form a hollow, sock-like, aerogel at the downstream end of the reactor.

A diastereoselective catalytic asymmetric hydrophosphination reaction was performed using a palladacycle catalyst to produce chiral PCP phosphine ligand with high dr (95:5) and excellent enantioselectivity (>99% ee). Subsequent facile metalation of the chiral ligand with Pt and Pd metal salts yielded the desired pincer complexes. The protonated form of these pincer complexes was also synthesised, and their structures were confirmed through the use of X-ray crystal diffraction and NMR spectroscopy analyses. [ABSTRACT FROM AUTHOR]

Catalytic synthesis of C 1 –C 4 hydrocarbons from clean synthesis gas, representative of natural gas, biomass or coal, was investigated over conventional supported catalyst (FeO x /Al 2 O 3 and FeO x /ZrO 2 ) and compared with catalytic cartridges made from anodized Al plates (FeO x /AAO-Al). Porous aluminum oxide layers (ca. 50 and 100 μm thick) and uniform meso/macro pores (ca. 25–50 nm, 50–75 nm diam.) were established on Al plates by anodization treatment. Iron was supplied by incipient wetness impregnation (particles), wet impregnation and ultrasonic spray deposition (plates). Catalysts were characterized by SEM, XPS, H 2 -TPR N 2 -BET and Hg porosimetry. Synthesis performance was studied at 350–500 °C, H 2 /CO ratios 1–3 and atmospheric pressure. Loading of FeO x and its reducibility was favoring gaseous products and determining reaction mode. Conditions were strongly favoring accumulation of carbonaceous material, being governing for performance and limiting lifetime. Low olefins selectivity (< 5%) and yields (< 1%) were obtained. Addition of 1 wt.% K favored syngas conversion and deactivation, 1.2 wt.% Cu caused no effect. Results indicate that large pores favor olefin selectivity and lifetime. The catalyst working state, as evolving during reaction was independent on initial state (calcined oxide, reduced, precursor nitrate salts), indicating that thermodynamics was structure controlling. [ABSTRACT FROM AUTHOR]

In the present study, we have developed a mathematic model describing quasi-continuous catalytic synthesis of multi-walled carbon nanotubes (MWCNTs) in a fluidized bed (FB) reactor. The special attention has been paid to the effects related to heat release or absorption during MWCNT synthesis. The heat of the reaction for MWCNT growth has been shown to significantly affect the thermal field in the reactor with the diameter as low as 6 cm. We attribute this to the extremely low thermal conductivity of aerogel-like MWCNT agglomerates (0.5–0.7 W/(m·K)), the basic units of the fluidized bed. According to the proposed model, the overheating up to 60 degrees takes place in the reactor with the diameter of D = 18 cm, the wall temperature of 943 K, and blown by 1:1 C 2 H 4 /Ar mixture. We have observed major changes caused by overheating: the activity of the catalyst and morphological properties of the produced MWCNTs (outer diameter, the structure of the walls, and fraction of impurities). The role of these thermal effects rises dramatically with increasing the reactor size and should be taken into account when designing reactors for large-scale production of MWCNTs. [ABSTRACT FROM AUTHOR]

Benzoin methyl ether (BME) is an important photosensitizer for coatings and printing technologies, and Cu/Cr hydrotalcite-like compounds (CuCr-HTLcs) is promising to be used as pollution-free catalyst for BME synthesis. However, little is known about effect of CuCr-HTLcs structure on catalytic synthesis of BME. In this work, a series of CuCr-HTLcs with different ratios of Cu to Cr (n Cu /n Cr ) was successfully prepared by a co-precipitation method. The structure of CuCr-HTLcs were systematically characterized. The copper and chromium in CuCr-HTLcs mainly exist in the form of Cu 2+ and Cr 3+ , respectively. The n Cu /n Cr has significant effects on crystallinity, acidity, and textural properties of CuCr-HTLcs. Subsequently, catalytic performance of CuCr-HTLcs was tested for BME synthesis. We found that BME synthesis is mainly influenced by combined effects of acid-site concentration and pore size. Moderate acid-site concentration and pore size (mesopores) are the critical factors for improving catalytic activity of CuCr-HTLcs and BME selectivity. [ABSTRACT FROM AUTHOR]

Polyethylene glycol (PEG) supported phosphorus chloride has been developed and used as an efficient and recyclable catalyst for dehydration of various aldoximes into the corresponding nitriles. This protocol has many advantages such as high conversion, high selectivity, short reaction time, mild reaction conditions, and simple experimental procedure. [ABSTRACT FROM PUBLISHER]

The floating catalyst chemical vapor deposition (FC-CVD) method is unique in providing the capability for continuous carbon nanotube (CNT) synthesis at an industrial scale from a one-step continuous gas-phase process. Controlling the formation of the iron-based catalyst nanoparticles is widely recognized as a primary parameter in optimizing both CNT product properties and production rate. Herein the combined influences of pyrolytic carbon species and catalytic nanoparticles are both shown to influence CNT aerogel formation. This work studies the source of carbon in the formed CNTs, the location of aerogel formation, the in-situ behaviour of catalyst nanoparticles and the correlated morphology of the resultant CNTs. Axial measurements using isotopically-labelled methane (CH 4 ) demonstrate that carbon within all CNTs is primarily derived from CH 4 rather than some of the early-forming CNTs being predominantly supplied with carbon via thermal decomposition of catalytic precursor components. Quantification of CNT production along the axis of the reactor definitively dispels the notion that injection parameters influence CNT formation and instead shows that bulk CNT formation occurs near the reactor exit regardless of the carbon source (CH 4 , toluene or ethanol). Supply of carbon to different reactor locations indicates that CNT aerogel formation will occur even when carbon is delivered near the exit of the reactor so long as the carbon source reaches a sufficient temperature (>1000 °C) to induce pyrolysis. These results give an indication of how future large-scale CNT reactors may be optimized and controlled by modifying downstream catalyst and carbon delivery. [ABSTRACT FROM AUTHOR]

Background: Hydrated strontium perchlorate [Sr(ClO4)2.3H2O] acts as a very strong oxidizing and dehydrating agent. Until now, it could not be reported as a catalyst in dehydration mechanism-based organic synthetic reactions. Therefore, it is important to find whether it could be an effective catalyst for one-pot multicomponent reactions (MCRs)., Objective: The main objective of the present work is the development of a novel process for the synthesis of 1,4-dihydropyrimidinones through the one-pot multicomponent strategy using hydrated Sr(ClO4)2 as a catalyst. Furthermore, it includes process optimization, stereoselectivity, and spectroscopic characterization of the synthesized compounds., Methods: Conventional and microwave-supported synthesis of 1,4-dihydropyrimidinones using 20 mol % of hydrated Sr(ClO4)2 catalyst via the one-pot solvent-free reaction was discovered as a new catalytic MCR methodology. The box-Behnken design approach and advanced analytical techniques were used for process optimization and reaction analysis., Results: The results confirmed that hydrated Sr(ClO4)2; works as an efficient catalyst for one-pot multicomponent organic synthesis under both conventional and microwave heating. It is an effective catalyst for laboratory synthesis of 1,4-dihydropyrimidinones stereoselectively with moderate to excellent yield without any undesirable effect. Microwave heating provided the desired product within 1-4 minutes. Moreover, this method provides easy isolation of the pure products simply by recrystallization, and without the use of a chromatographic purification method., Conclusion: The simplicity and neutrality of reaction conditions, easy post-reaction workup, higher satisfactory to excellent yield, effectiveness, the diversity of substrates, etc. render the hydrated Sr(ClO4)2 catalyst-based protocol for the stereoselective synthesis of 1,4-dihydropyrimidinones as a highly efficient method. Furthermore, it has been found to be safe un-der laboratory reaction conditions and no undesirable issues have been faced during the process., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

In the present study, copolymerization of ethylene and 1-hexene was conducted with a series of ansa-fluorenylamidodimethyltitanium complexes, including [t-BuNSiMe2Flu]TiMe2 (complex 1), [cyclododecylNSiMe2Flu]TiMe2 (complex 2) and [t-BuNSiMe2(2,7-t-Bu2Flu)]TiMe2 (complex 3), activated by MMAO. The effect of these catalysts on catalytic behavior, namely activity, molecular weight and monomer reactivity ratios, has been investigated. The results showed that all of them acted by a single site polymerization mechanism and the molecular weight distribution is independent of catalyst structure. Based on the study, it revealed that the introduction of a t-butyl at the 2,7 position on the fluorenyl ligand is able to enhance both catalytic activity and copolymer molecular weight more than introducing a cyclododecyl on the amine, which is probably associated with the electronic effect exerted by the t-butyl substituent. The comonomer incorporation content was controllable over a wide range by adjusting the comonomer feed ratio. Moreover, referring to monomer reactivity ratio exploration, it seems that the substitution on the ansa-fluorenylamidodimethyltitanium complex tends to hinder the insertion of 1-hexene into the polymer chain, leading to the highest 1-hexene content for traditional complex 1.

Owing to the unique synthetic routes, the nascent d-UHMWPE possesses nonequilibrium heterogeneous melt and significantly lower nascent entanglement density that endow nascent d-UHMWPE with optimized flowability, excellent solid-phase and melt processing performances. [Display omitted] The advent of nascent d-UHMWPE overcomes the intrinsic melting defects and crystal boundaries within the commercial UHMWPE (C-UHMWPE) based products, and opens the access to high value-added UHMWPE materials with long lifetime and improved qualities. The nascent d-UHMWPE derives from the disentanglement of UHMWPE that calls for suitable synthetic routes to d-UHMWPE. With a continuous development the synthesis of d-UHMWPE can be achieved either by single site catalysts or heterogeneous solid catalysts, and demonstrates a much easier processability within a wider temperature window. The processed d-UHMWPE demonstrates superior drawability, flexibility, toughness and thermal conductivity et al., and promises to be used in packages, bullet-proof armors, total knee/hip/ankle joint replacements, aerospace and marine engineering et al. The contribution systematically reviews the origin, catalytic synthesis, processing and applications of the nascent d-UHMWPE, and gives a detailed description on the conceptual proposal, the core and key points facing to the nascent d-UHMWPE. By analyzing the scientific problems still existing in the relating researches, the developmental trends and prospects of the nascent d-UHMWPE are envisioned. [ABSTRACT FROM AUTHOR]

A novel method for synthesis of 7-hydroxy-4-methylcoumarin from resorcinol and ethyl acetoacetate via the Pechmann reaction with polyvinylpyrrolidone-supported phosphotungstic acid (PVP–HPW) catalyst is developed. The catalysts were characterized by FTIR, TGA, elemental analysis, UV–vis and a Hammet acidity function test. HPW protonated PVP to form polymeric cations. The polymeric cations interacted strongly with phosphotungstic anions, leading to an ionic liquid structure. The performance of the PVP–HPW were compared with other catalysts such as HPW, NMP–H 2 SO 4 and PVP–H 2 SO 4 . For PVP–HPW dosage of 9% based on the weight of resorcinol, the yield of 7-hydroxy-4-methylcoumarin reached 96.73% after two hours reflux reaction at 110 °C, which exhibited much higher value than other catalysts. The PVP–HPW can be easily separated from the reaction mixture and retains the activity during recycling. [ABSTRACT FROM AUTHOR]

Response surface methodology (RSM) was successfully applied to study the synergistic effect of Pd/C and Novozyme 435 on the dynamic kinetic resolution of 1,1,1-trifluoroisopropylamine (TFPA). The variables taken into consideration were reaction temperature, substrate concentration, the Pd/C amount, and the Novozyme 435 amount. A statistical model was used to evaluate the influence of the variables on the conversion and enantiomeric excess (ee). It was found that the interaction between the Novozyme 435 and Pd/C was a significant parameter that affected TFPA conversion. The optimum conditions for RSM were: reaction temperature of 35°C, substrate (±) -- 1 concentration of 0.4mol/L, 60g/L of Novozyme 435, and 42.4g/L of Pd/C (3 wt% of Pd on active carbon). The actual experimental conversion was 95.6% under optimum conditions, which was comparable to the maximum predicted value of 95.7%. [ABSTRACT FROM AUTHOR]

A highly efficient and reusable catalyst, palladium (II) complex supported on functionalized silica, was prepared by anchoring palladium (II) onto 2,6-bis(5,6-dimethyl-1,2,4-triazine-3-yl)pyridine [BTP]-modified mesoporous silica (labeled as Pd-BTP/SiO2). The catalyst was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and Brunauer Emmett Teller (BET) analysis. Its catalytic performance was tested for the Heck coupling reactions between aryl halides with acrylic acid or styrene, and good to excellent results (higher conversions 87–96% and yields 66–78%) were obtained. The catalyst system was stable under the reaction conditions and could be successfully reused more than five times without the loss of catalytic activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • MWCNT system set of different diameters produced in FB reactor using Fe-Co catalysts. • A loss of homogeneous fluidization during the catalytic synthesis of MWCNTs is caused by adhesion of their primary agglomerates. • Catalyst morphology influences the formation of MWCNT agglomerates. • Controlling the catalyst particle concentration in FB prevents the formation of CNT clumps. • Coagulation model of the growth dynamics of MWCNT agglomerates in FB reactors was developed. The problem of the loss of homogeneous fluidization and the formation of large clumps of MWCNTs during their catalytic synthesis in a fluidized bed reactor has been studied experimentally and theoretically in terms of the impact of catalyst properties and synthesis process parameters. It has been shown that two factors play the most important role in the formation of large clumps of MWCNTs, namely, the ability of high-performance catalyst to produce agglomerates of MWCNTs with high cohesion, and a high concentration of catalyst particles in the fluidized bed volume. A relationship has been established between chemical components of the catalyst, its structure and cohesive properties of the MWCNT agglomerates formed on it. An approximate semi-analytical scheme for calculating the formation and growth of large fractal agglomerates (clumps) of MWCNTs during their catalytic synthesis in a fluidized bed has been developed. This approach is based on the model of sequential coagulation of MWCNT agglomerates starting from the primary ones, and made it possible to formulate the requirements for characteristics of the catalyst and parameters of the synthesis process, which ensure homogeneous fluidization in the reactor. [ABSTRACT FROM AUTHOR]

[Display omitted] • 5-hydroxymethylfurfural (HMF) and 2,5-dimethylfuran (DMF) are valuable chemicals. • HMF and DMF are synthesized from carbohydrate sources through catalytic pathway. • Reaction conditions and mechanism of forming HMF and DMF are thoroughly analyzed. • Yield of HMF and DMF using various catalysts and reaction conditions are evaluated. In recent years, green energy sources have been proposed as alternatives for fossil fuels to meet energy demand while minimizing environmental pollution and global climate change. In this context, agricultural residues can be catalytically converted into furan derivatives. Among furan-based compounds, 5-hydroxymethylfurfural (HMF) and 2,5-dimethylfuran (DMF) are the valuable chemicals that can be converted into desired materials, including fuels. This review article discusses various catalytic HMF and DMF production pathways and the influence of feedstocks, catalysts, solvents, and hydrogen donors on the process yield. Additionally, reaction temperature and H 2 pressure effects on the feedstock conversion and HMF and DMF production yields are also presented. The primary attention has been devoted to the literature published in the last five years. However, additional relevant examples have also been discussed to clarify the topic further where necessary. This review aims at providing state-to-the-art information on the current developmental state of DMF and HMF production for researchers in this field. [ABSTRACT FROM AUTHOR]

The demonstration operation of an pilot-scale bio-dimethyl ether(DME) synthesis system was carried out for with 300-350 kg/h of wood chips as feedstock. The tar content was 4.4-5.7 g/Nm 3 and carbon percent in the residual char was low due to the combined advantages of the specific gasifier combining with upstream and downstream gasification with O 2 -rich air(46.3vol%), fed through the top and bottom inlets of the gasifier. Steam, as the secondary gasifying agent, also increased H 2 content in the raw bio-syngas. The reforming of tar and light hydrocarbons further decreased tar content to 0.42-0.67 g/Nm 3 over Ni-MgO/γ-Al 2 O 3 cordierite monolithic catalysts with less than 5.0vol% of CH 4 content in the raw bio-syngas. CO 2 removal efficiency was about 70% by pressure-swing unit(PSA), using propylene carbonate as adsorbent. CO conversion and space-time yield of DME over Cu/Zn/Al/HZSM-5-packed fixed-bed tubular reactor were 61.4-71% and 90.4-155.8 kg/m cat 3 /h respectively when the gas hourly space velocity(GHSV) was 650-1500 h -1 at 220 o C and 4.3 MPa. The selectivity of methanol and hydrocarbons were than less 3% under the typical operation condition. About 15.7% carbon of dried wood chip was converted to DME with the production cost of ca. ¥4810/ton DME. [ABSTRACT FROM AUTHOR]

Heterogeneous synthesis of 3,3′-dimethyl-4,4′-diaminodiphenylmethane (MDT) from o -tolylamine and formaldehyde on acidic zeolites HY, HZSM-5, Hβ and TS-1 was investigated. Hβ zeolite with strong Bronsted acidity and proper textural property demonstrated better catalytic performance than other three zeolites for this synthetic reaction. Yield and selectivity of product MDT from the catalytic reaction over Hβ strongly depended on temperature, and optimal reaction temperature appeared to be about 433 K. Based on analyses of LC/MS and 1 H NMR for reaction intermediates, it was suggested that the synthetic process went through multiple steps involving intermediates o -tolylamino-methanol, methylene- o -tolylamine, N,N ′-di-o-tolyl-methanediamine and 2-methyl-4-( o -tolylamino-methyl)-phenylamine. Interpretation to the mechanism of various intermediates formation and conversion was presented. [ABSTRACT FROM AUTHOR]

In the present study, sulfated derivatives of Artemisia sphaerocephala polysaccharide (SASP) with high degree of substitution (DS) were synthesized by using 4-dimethylaminopyridine (DMAP)/dimethylcyclohexylcarbodiimide (DCC) as catalyst in homogeneous conditions. It was found that DMAP/DCC showed marked improvement in DS of sulfated samples. Compared to sulfated derivatives without catalyst, the DS of SASP increased from 0.91 to 1.28 with an increment in dosage of DMAP from 0 to 10 mg. The influence of DMAP/DCC on the DS of sulfated derivatives was depended on the content of DMAP. The effect of DMAP might be due to its strong coordination to the hydroxy group. The results of FT-IR and X-ray photoelectron spectroscopy (XPS) indicated that SO 3 − group (S 6+ , binding energy of 172.3 eV) was widely present in sulfated polysaccharide molecules. 13 C NMR results indicated that C-6 substitution was predominant for sulfated polysaccharide when compared with other positions. In the sulfation reaction, a sharp decrease in M W was observed. DMAP/DCC was an effective catalyst system in sulfated modification of polysaccharide. [ABSTRACT FROM AUTHOR]

The effective utilization of glycerol, a by-product in the production of biodiesel, into useful chemicals is desirable from the viewpoint of green chemistry. With this in mind, a novel and highly selective route to synthesizing glycerol dimethyl ether (2,3-dimethoxy-1-propanol), a potential fuel additive, from glycerol was proposed. This route uses both glycerol and methanol as starting materials, takes epichlorohydrin as an intermediate product, and utilizes HCl as a recycling agent. Hereinto, the key step of this route is the reaction between epichlorohydrin and methanol to produce 2,3-dimethoxy-1-propanol which is identified by GC–MS, ESI-MS, IR and NMR. The thermodynamics of this reaction was analyzed and the result showed that the thermodynamics of a reaction was favorable and a high product yield was expected. The effect of various parameters such as kind of acid catalyst, molar ratio of epichlorohydrin to methanol, reaction temperature and reaction time was studied. Among various acid catalysts investigated, the acidic ionic liquid [HSO 3 -b-N(CH 3 ) 3 ]HSO 4 exhibited the highest activity and selectivity: conversion of epichlorohydrin of 100% and selectivity of 2,3-dimethoxy-1-propanol of 99% at 393 K, 10 h, an initial pressure of 0.1 MPa and a molar ratio of catalyst:ECH:CH 3 OH of 0.01:1:5. After the reaction, [HSO 3 -b-N(CH 3 ) 3 ]HSO 4 was separated by vacuum distillation and then reused for the next cycle directly. The results showed that the product selectivity remained at about 94% but the conversion of epichlorohydrin dropped to 75% after being used five times. Subsequently, a reaction mechanism for the synthesis of 2,3-dimethoxy-1-propanol from epichlorohydrin and methanol was proposed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Artemisia sphaerocephala polysaccharide was firstly sulfated by using DMAP/DCC as catalyst. [•] Chemical modification resulted in the change of conformational properties. [•] M W and DS can take a particular role in solution conformation. [•] Sulfation modification could enhance the antioxidant activities of ASP. [ABSTRACT FROM AUTHOR]

Methyl phenyl carbonate (MPC) is one of the versatile carbonates; in particular, it is an important component in lithium-ion batteries. In recent years, the catalytic synthesis of MPC has become an important topic, but the development of highly active catalysts is still challenging. In this study, SBA-15-loaded nano-sized Pb–Bi catalysts with different Pb/Bi molar ratios were prepared by deposition–precipitation to improve the efficiency and selectivity. To investigate the relationship between the structure and performance of the catalysts, XRD, BET, SEM-EDS, HRTEM, H 2 -TPR, and XPS characterization, as well as catalytic activity and stability tests, were conducted. Results revealed that Pb–Bi/SBA-15 can efficiently catalyze the synthesis of MPC under solvent-free conditions, with the highest catalytic activity obtained over 6 Pb–1Bi/SBA-15. SBA-15 with a large pore size and a high specific surface area was suitable as catalyst carrier, and the average diameter of Pb–Bi oxide particles was ∼3.57 nm. The addition of Bi led to the improved dispersion of active components, which were highly and evenly dispersed on the SBA-15 surface. Furthermore, an appropriate proportion of Pb and Bi on SBA-15 was conducive to the considerable enhancement of the catalytic activity. Besides, Pb–Bi/SBA-15 also exhibited good durability and recyclability, making it a promising catalytic material for the synthesis of various carbonates. SBA-15-loaded nano-sized Pb–Bi catalysts were synthesized by a deposition-precipitation method, which can efficiently catalyze the synthesis of MPC without the use of a solvent. The 6 Pb–1Bi/SBA-15 catalyst exhibited the highest catalytic activity as well as superior stability and recyclability. [Display omitted] • Efficient synthesis of methyl phenyl carbonate was performed using a Pb–Bi bimetallic catalyst. • Methyl phenyl carbonate was obtained in high yield and selectivity without solvent. • Formation of a highly dispersed Pb–Bi alloy on the catalyst surface was verified. • A facile catalytic approach for efficient synthesis of various organic carbonates was presented. [ABSTRACT FROM AUTHOR]

Imines were synthesized from benzyl alcohol and amines by using catalysts of gold nanoparticles supported on ZrO (Au/ZrO). The effects of reaction time, temperature, gold loadings and base were investigated. High yields were achieved under moderate conditions (60 °C) in the presence of KOCH. For instance, the yield of N-benzylidenebenzylamine produced from benzyl alcohol and benzylamine on 3 wt% Au/ZrO is 87 %. The synthesis of imine involves two reaction steps: selective oxidation of benzyl alcohol to benzaldehyde and the coupling reaction of amines with benzaldehyde. In the first step, the base promotes the selective oxidation. The reactions of benzyl alcohol with three different amines, aniline, n-butylamine and benzylamine, were conducted to produce corresponding imines. The results show that the amine with stronger nucleophilicity has better ability to react with benzaldehyde in the second step, resulting in higher yield of the corresponding imine. We proposed a tentative mechanism for the synthesis process. [ABSTRACT FROM AUTHOR]

This article presents results of a characterization study undertaken on a Mg-Fe-Mn-Ni alloy for hydrogen storage application. This Mg-Fe-Mn-Ni alloy undergoes rapid activation in less than five charging/discharging runs and is able to reversibly uptake 5 mass% H2. The charging/discharging characteristics of this alloy are evaluated as a function of temperature. The optimal temperatures for hydriding and dehydriding are identified as 325.5°C and 372°C, respectively. The kinetics data are fitted to lumped first-order reaction models as well as to a spherically symmetric diffusion model with first-order kinetics. Based on the analysis, model constants are derived. Further, based on the van ‘t Hoff equation, the formation enthalpy and entropy are determined as 65 ± 3.1 kJ/mole and 101 ± 4.7 J/mole K, respectively. [ABSTRACT FROM PUBLISHER]

Abstract: A new series of functional 2-benzyl-1,2-dihydro[60]fullerenes, BnHCs, were synthesized efficiently via co-catalyzed selective monofunctionalization of C60 with functional benzyl bromides. Photophysical and electrochemical properties of the new BnHCs were investigated. PSCs based on 2-MeO–4-CO2Me–BnHC as new acceptor and P3HT as donor showed a power conversion efficiency of 3.75%, which is comparable to that of PC61BM under the same device conditions. [Copyright &y& Elsevier]

An efficient catalytic method for the synthesis of α, β-diamino acid derivatives has been developed via regioselective ring opening of aziridines by amines in the presence of indium(III) salt under very mild reaction conditions. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file. [ABSTRACT FROM AUTHOR]

A novel low-temperature method is described for the direct synthesis of FeO/mica pearlescent pigments with ferric chloride as a precursor and trace Fe(II) as a catalyst which does not require any calcination step. The as-synthesized pigments are characterized in detail by means of different techniques including X-ray diffraction, field emission scanning electron microscopy, energy dispersive spectroscopy, and colorimetry. The influence of various factors on the transformation from Fe(OH) coating layer to crystalline hematite coating layer is investigated, respectively. Furthermore, this paper studies several critical technological parameters pertaining to the influences on morphology and color properties of the pigments such as the coating temperature and the pH value. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of propyl gallate using Brønsted acidic ionic liquid N-methyl pyrrolidonium hydrosulfate [Hnmp]HSO4 as an efficient catalyst with gallic acid and n-propanol as materials was studied. The influence factors, such as the selection of water-carrying agent, reaction temperature, molar ratio of reactants, the dosage of catalyst, and the reaction time were also investigated. The results showed the optimum reaction conditions were as follows: the molar ratio of n-propanol and gallic acid and catalyst was 5:1:0.3, reaction time was 5h and the yield of propyl gallate was up to 89.8% without water-carrying agent at 95–105°C. [Copyright &y& Elsevier]

In the present study, copolymerization of ethylene and 1-hexene was conducted with a series of ansa-fluorenylamidodimethyltitanium complexes, including [t-BuNSiMe2Flu]TiMe2 (complex 1), [cyclododecylNSiMe2Flu]TiMe2 (complex 2) and [t-BuNSiMe2(2,7-t-Bu2Flu)]TiMe2 (complex 3), activated by MMAO. The effect of these catalysts on catalytic behavior, namely activity, molecular weight and monomer reactivity ratios, has been investigated. The results showed that all of them acted by a single site polymerization mechanism and the molecular weight distribution is independent of catalyst structure. Based on the study, it revealed that the introduction of a t-butyl at the 2,7 position on the fluorenyl ligand is able to enhance both catalytic activity and copolymer molecular weight more than introducing a cyclododecyl on the amine, which is probably associated with the electronic effect exerted by the t-butyl substituent. The comonomer incorporation content was controllable over a wide range by adjusting the comonomer feed ratio. Moreover, referring to monomer reactivity ratio exploration, it seems that the substitution on the ansa-fluorenylamidodimethyltitanium complex tends to hinder the insertion of 1-hexene into the polymer chain, leading to the highest 1-hexene content for traditional complex 1. [ABSTRACT FROM AUTHOR]

Based on the principles of microbial fermentation, cytoarchitectonics, and biomineralization, we have developed a novel synthetic method by which the multilayered nanostructure of yeast cell tissues can be copied by phosphates. Taking living yeast cells as catalytic templates and reactors, a series of hierarchical mesoporous Ca-, Zn-, Mg-, and Ti-phosphate-protein nanocomposites with complex surface shapes are synthesized under ambient conditions, and their scale-up syntheses are carried out. The results show that the structure and composition of the synthesized nanocomposites have good repetition and they can be produced in a large quantity. The mechanism of biomineralization for gene regulation in yeast cells was discussed. The present method has many advantages, including the mild reaction conditions, simple process, no pollution, and ease of industrial production. [ABSTRACT FROM AUTHOR]

Abstract: Ethanol produced from lignocellulosic biomass through a number of conversion pathways presents a more viable alternative to fossil fuels because non-food feedstocks are used. The approaches for ethanol production from biomass, such as wood, can be classified into three general pathways: hydrolysis fermentation (hydrolysis followed by fermentation of the sugars), gasification biosynthesis (gasification followed by biosynthesis to ethanol), and gasification chemical synthesis (gasification followed by catalytic synthesis to ethanol). To compare performance of the three pathways, a black-box system model was utilized with relevant assumptions to analyze their mass and energy conversion efficiencies. Their processing times were also estimated. A comprehensive comparison of the modeling results showed that from a process engineering standpoint, the feasibility of the biomass refining pathways ordered from high to low is gasification chemical synthesis, hydrolysis fermentation, then gasification biosynthesis. Calculations of a performance index, a singular number incorporating the major input and output and processing time of a pathway that was defined, also supported this order. [Copyright &y& Elsevier]

Sugar vinyl ethers and vinyl glycosides are conveniently synthesized by catalytic transfer vinylation with butyl vinyl ether, which serves as both the solvent and source of vinyl. The air-stable catalyst (4,7-diphenyl-1,10-phenanthroline)Pd(OOCCF3)2 is prepared in situ from commercially available components. [ABSTRACT FROM AUTHOR]

Abstract: Spherical hematite particles have been quickly synthesized by heating Fe(OH)3 gel with trace Fe(II) in aqueous solution to reflux temperature. The final product is characterized by XRD, TEM, HRTEM, and FT-IR techniques. The influence of various factors on the size and morphology of hematite particles is investigated, respectively. The growth mechanism of hematite particles is also discussed. The results show that both the mechanisms, dissolution/reprecipitation and solid state transformation, work alternately in the transformation process from Fe(OH)3 to hematite particles until the transformation is finished. The magnetism of the product is also studied. [Copyright &y& Elsevier]