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Applied Catalysis A, General (v.454, #)
Silica encapsulated magnetic nanoparticles-supported Zn(II) nanocatalyst: A versatile integration of excellent reactivity and selectivity for the synthesis of azoxyarenes, combined with facile catalyst recovery and recyclability by R.K. Sharma; Yukti Monga (pp. 1-10).
Display Omitted► Novel silica based magnetically recoverable zinc nanocatalyst synthesized by grafting method. ► Characterizations and application of organic–inorganic hybrid catalyst. ► Efficient method for the oxidation of aromatic amines to yield azoxyarenes. ► Catalyst shows high activity and selectivity for concurrent six reactions. ► Easy recyclability of catalyst using external magnet.A novel and highly efficient zinc based nanocatalyst has been synthesized by covalent grafting of 2-acetylpyridine on amine functionalized silica@magnetite nanoparticles, followed by metallation with zinc acetate. The resulting nano-composite was found to be highly efficient for oxidation of various aromatic amines to give azoxyarenes. The prepared nanocatalyst was characterized by Electron microscopy techniques (SEM and TEM with EDS), X-ray diffraction (XRD), vibrational sampling magnetometer (VSM), Fourier transform infrared spectroscopy (FT-IR) and atomic absorption spectroscopy (AAS) techniques. High turnover number (TON), mild reaction conditions and high selectivity for azoxyarenes with sustained catalytic activity makes present protocol worthy and highly compliant as compared to the other non-magnetic heterogeneous catalytic system. The acquisition of this nanocatalyst is also exemplified by employing the catalyst in leaching and reusability test and the results from the tests showing negligible zinc leaching and recycling was achieved multiple times just by sequestering using an external magnet.
Keywords: Silica; 2-Acetylpyridine; Magnetite nanoparticles; Zinc; Azoxyarenes
Synthesis, characterization and catalytic activity toward dye decolorization by manganese (II) mononuclear complexes by Camila A. Wegermann; Paola Strapasson; Stela M.M. Romanowski; Adailton Bortoluzzi; Ronny R. Ribeiro; Fábio S. Nunes; Sueli M. Drechsel (pp. 11-20).
Display Omitted► Dye decolorization reactions using manganese complexes as catalysts. ► Complete structural characterization of the catalysts. ► Radical scavenger tert-BuOH reduces reaction rates indicating a radical mechanism. ► MnIV and MnIIIMnIV species detected in reaction medium by EPR spectroscopy.Manganese(II) perchlorate reacts with L1= N,N,N′-tris(2-methylpyridyl)- N′-hydroxyethyl-ethylenodiamine and L2= N-(2-hydroxybenzyl)- N,N′-bis(2-methylpyridyl)- N′-hydroxyethyl-ethylenodiamine in ethanol to form the corresponding complexes [MnL1(H2O)](ClO4)2 and [MnL2]ClO4. Both complexes crystallize in the monoclinic system and space group P 21/ n. In [MnL1(H2O)]2+ and [MnL2]+ the manganese(II) ion is heptacoordinated and hexacoordinated, respectively. FTIR, elemental analysis and conductance measurements were all in accordance with the molecular structures of [MnL1(H2O)](ClO4)2 and [MnL2]ClO4. The ability of [MnL1(H2O)](ClO4)2 and [MnL2]ClO4 to catalyze the oxidation of the dyes methyl orange and reactive orange 16 was studied in aqueous alkaline solution (carbonate/bicarbonate buffer). Both complexes were active catalysts promoting significant enhancement of dye solution decolorization in comparison to control reactions.
Keywords: Manganese; Hydroxyethyl-ethylenodiamine; Crystal structure; EPR; Dye decolorization; H; 2; O; 2
One-pot catalytic conversion of Nordic pulp media into green platform chemicals by Johan Ahlkvist; Samikannu Ajaikumar; William Larsson; Jyri-Pekka Mikkola (pp. 21-29).
Display Omitted► Comparison of Nordic pulp as raw material for green platform chemicals. ► A low-cost heterogeneous catalyst, Amberlyst 70, was used as a recyclable catalyst. ► The yield of both levulinic and formic acids obtained was around 50–55%. ► The hydrolytic system operates without energy-intensive pre-treatment procedures.In this paper, both sulfite and sulfate (kraft) celluloses from Nordic pulp mills were used as raw materials in the catalytic one-pot synthesis of green platform chemicals, levulinic and formic acids, respectively. The catalyst of choice was a macro-porous, cationic ion-exchange resin, Amberlyst 70. The optimal reaction conditions were determined and the influence of various gas atmospheres was investigated. The maximum yields of 53% formic acid and 57% of levulinic acid were separately obtained in a straight-forward conversion system only containing cellulose, water and the heterogeneous catalyst. The concept introduces a one-pot procedure providing a feasible route to green platform chemicals obtained via conversion of coniferous soft wood pulp to levulinic and formic acids, respectively.
Keywords: Wood pulp; Solid acid catalysis; Amberlyst 70; Levulinic acid; Formic acid
Photocatalytic activity of aqueous WO3 sol for the degradation of Orange II and 4-chlorophenol by Suzuko Yamazaki; Taiki Yamate; Kenta Adachi (pp. 30-36).
Display Omitted► Orange II was degraded photocatalytically in aqueous WO3 sol. ► Effect of various reaction conditions on the degradation rate was examined. ► Mechanism and rate law were proposed to account for the obtained kinetic data. ► Mixing of WO3 with TiO2 enhanced significantly the degradation rate. ► Enhancement of activity by mixing sols was confirmed for the degradation of 4-CP.Photocatalysis of a transparent aqueous WO3 sol was investigated for the color-fading of Orange II. Dependence of the degradation rate of Orange II on pH and ionic strength of the WO3 sol was explained in terms of the electrostatic interaction between Orange II and the WO3 colloid particles. The degradation rate follows the first-order kinetics with respect to the concentration of Orange II. It was demonstrated that the photogenerated electron in WO3 reduced O2 effectively since the photochromism of the WO3 sol observed under nitrogen atmosphere did not occur under air-saturated condition. The photocatalytic activity of WO3 was lower than that of TiO2 by a factor of 0.5 and was enhanced by mixing with the TiO2 sol. The best photocatalytic performance for the degradation of Orange II was obtained by using the mixed sol with WO3:TiO2 molar ratio of 1:2. Similar enhancement in the photocatalytic activity was confirmed for the degradation of 4-chlorophenol.
Keywords: Photocatalyst; Tungsten oxide; Titanium dioxide; Sol; Kinetics
Benzene reduction in gasoline by alkylation with propylene over MCM-22 zeolite with a different Brønsted/Lewis acidity ratios by Georgina C. Laredo; Roberto Quintana-Solórzano; J. Jesús Castillo; Héctor Armendáriz-Herrera; Jose Luis Garcia-Gutierrez (pp. 37-45).
Display Omitted► Two MCM-22 zeolites with different Brønsted/Lewis ratio were prepared. ► The catalysts were tested in the alkylation of the benzene present in a real feed. ► The catalyst with the higher B/L ratio was much more resistant to deactivation. ► The higher stability of the catalyst depended mostly on the Brønsted/Lewis ratio. ► Location of the active sites appears to have an important role in the deactivation.In this work, the liquid phase alkylation of benzene with propylene was carried out over MCM-22 zeolite treated thermally in a flow of air and nitrogen for activation. Such activation procedures led to changes in the Brønsted/Lewis acidity ratio of the samples, but not in textural properties. The alkylation reaction was conducted using as a feed a benzene-enriched sample of reformate heart cut containing ca. 20wt% benzene. The experimental reaction was performed in a batch reactor at 220°C adjusting the amount of propylene for a molar ratio of benzene to propylene in the feed of 2. Benzene conversion versus time profiles consisted of three regions wherein (i) the aromatic conversion decreased very slightly, (ii) it diminished drastically, and (iii) it continued dropping with time, but to a lesser extent than in (ii). MCM-22 sample containing a higher Brønsted acidity exhibited a larger resistance to deactivation during benzene alkylation experiments, as severe deactivation starts after 19h of time on stream. Concerning products distribution, the presence of bulky (poly) alkylated products declined as the MCM-22 became more deactivated.
Keywords: Gasoline; Benzene; Propylene; Alkylation; MCM-22 zeolite; Acid sites
Robust bimetallic Pt–Ru catalysts for the rapid hydrogenation of toluene and tetralin at ambient temperature and pressure by Jessica N.G. Stanley; Falk Heinroth; Cameron C. Weber; Anthony F. Masters; Thomas Maschmeyer (pp. 46-52).
Display Omitted► Alloy nanoparticles of Pt–Ru were synthesised. ► The complete catalyst synthesis was performed in air. ► Toluene was hydrogenated under ambient conditions and with no special precautions. ► The alloy with a molar ratio of 1 Pt to 1.5 Ru was much more active than either of the metals by themselves. ► The synergistic alloy may hold the key to a simple reversible hydrogen storage system, operating under mild conditions.To facilitate the drive towards ever lower energy, ‘greener’ processing, robust bimetallic aluminosilicate-supported Pt–Ru catalysts that can operate under atmospheric conditions have been developed for the rapid room temperature hydrogenation of aromatics (toluene and tetralin) at 1atm H2. The toluene/methylcyclohexane couple has the added interest of being a promising cyclic hydrocarbon combination for the storage of hydrogen.The easily handled air-stable catalysts were prepared using the incipient wetness method and characterised by ICP-AES, XRD, TEM as well as nitrogen sorption measurements. Compared to their monometallic counterparts, the bimetallic catalysts displayed significantly higher turn-over-frequencies (TOFs), consistent with a synergistic relationship between platinum and ruthenium.
Keywords: Hydrogenation; Alloy; Catalyst; Toluene; Platinum; Ruthenium; Hydrogen storage
Catalytic activity of Au/TiO2 and Pt/TiO2 nanocatalysts prepared with arc plasma deposition under CO oxidation by Sang Hoon Kim; Chan-Ho Jung; Nruparaj Sahu; Dahee Park; Jung Yeul Yun; Heonphil Ha; Jeong Young Park (pp. 53-58).
Display Omitted► Novel synthesis of nanocatalysts fabricated by arc plasma deposition is reported. ► The particle size of the gold nanoparticles can be controlled by APD voltage. ► The catalytic activity of the Au/TiO2 samples showed size dependence.We report the catalytic activity of Au/TiO2 and Pt/TiO2 nanocatalysts under CO oxidation fabricated by arc plasma deposition (APD), which is a facile dry process involving no organic materials. Using APD, the catalyst nanoparticles were well dispersed on the TiO2 powder with an average particle size of 2–4nm, well below that of nanoparticles prepared by the sol–gel method (10nm). We found that the average particle size of the dispersed gold nanoparticles can be controlled by changing the plasma discharge voltage of APD. Accordingly, the amount of gold loaded on the TiO2 powder increased as the discharge voltage increased, but the specific surface area of the Au/TiO2 samples decreased. As for catalytic reactivity, Au/TiO2 showed a higher catalytic activity than Pt/TiO2 in CO oxidation. The catalytic activity of the Au/TiO2 samples showed size dependence where higher catalytic activity occurred on smaller gold nanoparticles. This study suggests that APD is a simple way to fabricate catalytically active nanocatalysts.
Keywords: Arc plasma deposition; Au and Pt nanoparticles; Nanocatalyst; CO oxidation
Photodegradation of p-nitrophenol using octahedral Cu2O particles immobilized on a solid support under a tungsten halogen lamp by Wei Zhai; Fengqiang Sun; Wei Chen; Zizhao Pan; Lihe Zhang; Shaohua Li; Shuilan Feng; Yiyi Liao; Weishan Li (pp. 59-65).
Display Omitted► Octahedral Cu2O particles on ITO glass were used in photodegradation of pollutants. ► They showed high abilities in degradation of p-nitrophenol in the presence of H2O2. ► The light, the Cu2O particle and the added H2O2 all acted dual roles. ► Such particles could be easily recycled with steady high activity. ► The particles could be used in degradation of other phenolic pollutants.Octahedral Cu2O particles were prepared on an indium-tin oxide glass via electrodeposition and were employed in the catalytic degradation of p-nitrophenol in the presence of H2O2. Under irradiation of a warm visible-light source, tungsten halogen lamp, Cu2O particles not only acted as a photocatalyst, but might also act as a thermal-catalyst to induce the decomposition of H2O2 and produce O2 at higher temperatures. The photogenerated electrons and holes could react with H2O2, O2, and H2O to produce abundantOH radicals, resulting in the effective oxidation of p-nitrophenol. High-performance liquid chromatography measurements of degradation intermediates showed that p-nitrophenol was first decomposed into hydroquinone and benzoquinone and then mineralized. The degradation efficiency was dependent on electrodeposition time, light intensity, H2O2 amount, and solution temperature. This catalyst could be easily recycled and used in the efficient degradation of other phenolic compounds.
Keywords: Octahedral Cu; 2; O particles; Electrodeposition; p; -Nitrophenol; Photodegradation
The adsorption and reaction of alcohols on TiO2 and Pd/TiO2 catalysts by Hasliza Bahruji; Michael Bowker; Catherine Brookes; Philip R. Davies; Ibrahim Wawata (pp. 66-73).
Display Omitted► We report decomposition pathways for alcohol decomposition on titania and Pd–TiO2. ► These catalysts are active for photocatalytic reforming and hydrogen production. ► Two dehydration pathways are identified on titania, monomolecular and bimolecular. ► With Pd addition pathways are changed to mainly dehydrogenation/decarbonylation. ► We suggest that reverse spillover of ethoxy occurs from the support to the metal nanoparticles.The decomposition of alcohols (methanol, ethanol, n-propanol, i-propanol) on TiO2 and Pd/TiO2 catalysts has been studied using temperature programmed desorption. The alcohols mainly decompose via a dehydration pathway on TiO2 catalysts, with no evidence for reactions involving α CC scission or dehydrogenation. However, the reaction pathway was fundamentally altered by the presence of Pd nanoparticles, and products of α CC scission became dominant due to decarbonylation pathways. For the reaction with ethanol, there was no evidence of the dehydration product ethylene even though the surface is mainly composed of titania, indicating that diffusion of alkoxy species from the support to the Pd occurs efficiently during TPD. However, competing dehydration reactions did occur on Pd/TiO2 in the cases of n-propanol and i-propanol decomposition which is postulated to be due to more limited diffusivity of the bulkier alkoxides.
Keywords: Alcohol reactivity; TPD; Methanol; Ethanol; Propanol; TiO2 catalyst; Pd–TiO2 catalyst; Photocatalysis
Metal cations intercalated titanate nanotubes as catalysts for α,β unsaturated esters production by Neilson M. dos Santos; Jardel M. Rocha; Jose M.E. Matos; Odair P. Ferreira; Josué M. Filho; Bartolomeu C. Viana; Alcineia C. Oliveira (pp. 74-80).
Display Omitted► TNTs were synthesized by hydrothermal treatment. ► Cu, Co, Ce or La nanoparticles-containing TNT were characterized by BET XRD, TEM and Raman measurements. ► Ce and La were active in the α,β-unsaturated esters production. ► Accessibility of the nanoparticles on TNT surface resulted in best catalytic performances.Characterization and catalytic performances of cations (M=Ce4+, La3+, Co2+, Cu2+ or Na+) intercalated titanate nanotubes (MTNT) were performed for α,β unsaturated esters production. Structural properties of the solids were evaluated by transmission electron microscopy (TEM) analysis and X-ray diffraction (XRD), and Raman spectroscopy measurements whereas textural properties were obtained through nitrogen adsorption–desorption isotherms. The transition metals were intercalated in titanate nanotubes by ionic exchange reaction where the Na+ cations were substituted by Ce4+, La3+, Co2+ and Cu2+ ones. Also, the structural characterizations revealed that the ion-exchange processes can favour the formation of nanosized oxides on the TNT surfaces, in some cases. Textural analysis showed high surface area, pore volume and diameters, but a superior catalytic activity and recyclability was only observed for CeTNT and LaTNT catalysts. The improved performance of CeTNT was believed to be related to the presence of Ce4+ cations in the interlamellar region and CeO2 nanosized particles on TNT surface as well.
Keywords: Titanate nanotubes; Ion exchange; α,β unsaturated esters; Condensation reaction
C2-oxygenates synthesis through CO hydrogenation on SiO2-ZrO2 supported Rh-based catalyst: The effect of support by Lupeng Han; Dongsen Mao; Jun Yu; Qiangsheng Guo; Guanzhong Lu (pp. 81-87).
Display Omitted► SiO2-ZrO2 supported catalyst exhibited better activity and C2 oxygenates selectivity. ► SiO2-ZrO2 supported catalyst has higher dispersion of Rh. ► SiO2-ZrO2 supported catalyst has more Rh+ sites for CO insertion. ► SiO2-ZrO2 supported catalyst promotes CO dissociation. ► SiO2-ZrO2 supported catalyst has moderate ability for hydrogenation.Rh-Mn-Li catalysts supported on SiO2, ZrO2 and SiO2-ZrO2 mixed oxides with various molar ratios of Si/Zr were prepared and tested for the synthesis of C2-oxygenates from syngas. Compared with pure SiO2 and ZrO2 supported catalysts, catalysts supported on SiO2-ZrO2 mixed oxides showed higher activity and C2-oxygenates selectivity, in which Rh-Mn-Li/SiO2-ZrO2 (molar ratio of Si/Zr=1:3) exhibited the best yield of C2-oxygenates. The effect of the support on the performance of the Rh-based catalysts was investigated comprehensively by XRD, N2 adsorption-desorption, H2 and CO uptakes, FT-IR, XPS, H2-TPR, TPSR and CO-TPD techniques. The results indicated that the chemical state of Rh, CO adsorption species, dispersion of Rh and the ability of CO hydrogenation varied over catalysts supported on SiO2, ZrO2 and SiO2-ZrO2 mixed oxides, which led to the diverse catalytic activity toward C2-oxygenates synthesis.
Keywords: Syngas; C; 2; -oxygenates; Rh-based catalyst; SiO; 2; -ZrO; 2; mixed oxide
A novel hydrofobic niobium oxyhydroxide as catalyst: Selective cyclohexene oxidation to epoxide by Poliane Chagas; Henrique S. Oliveira; Raquel Mambrini; Mireille Le Hyaric; Mauro V. de Almeida; Luiz C.A. Oliveira (pp. 88-92).
Display Omitted► It was produced a modified niobia with high catalytic capacity for cyclohexene oxidation using hydrogen peroxide. ► Niobium oxyhydroxide has been modified and studied as a heterogeneous catalyst for cyclohexene epoxidation. ► The material was treated with hydrogen peroxide to generate oxidizing groups ( peroxo species) on the surface.A surface modified niobium oxyhydroxide catalyst was utilized for the selective liquid-phase oxidation of cyclohexene to epoxide in the presence of hydrogen peroxide. After surface modification with a surfactant (cetiltrimetilamonium bromide -CTAB), the very active niobium oxyhydroxide (NbO2OH), presented hydrophobic characteristics and good activity for the oxidation of cyclohexene over the heterogeneous catalyst. Furthermore, the hydrophobic material presented a high selectivity toward the formation of the epoxide species. The mass spectrometry analysis of the reaction showed that epoxide species was produced with a selectivity of 60% using 0.2mL of hydrogen peroxide, with 65% of conversion. The results strongly suggest that the reaction involves oxidizing species generated after the reaction with H2O2. The surfactant anchored over the niobium catalyst promotes a better interaction with the nonpolar substrate.
Keywords: Niobium oxyhydroxide; Hydrogen peroxide; Cyclohexene; Epoxide
Catecholase activity investigations using in situ copper complexes with pyrazole and pyridine based ligands by A. Mouadili; A. Attayibat; S. El Kadiri; S. Radi; R. Touzani (pp. 93-99).
Display Omitted► All copper complexes formed in situ catalyze the oxidation reaction of catechol. ► Oxidation reaction rate depends on four parameters. ► The highest rate activity is given byL4 [Cu(CH3COO)2].The in situ copper (II) complexes of six pyrazole and pyridine based ligands: 1-[5-methyl-1-pyridin-2-yl-1H-pyrazol-3-yl] methanolL1, 2-(3,5-dimethyl-pyrazol-1-yl)-pyridineL2, (5-methyl-3-pyridin-2-yl-1H-pyrazol-1-yl) ethyl acetateL3, 1′,5,5′-trimethyl-1′H-1,3′-bipyrazol-3-ethyl carboxylatL4, (1′,5,5′-trimethyl-1′H-1,3′-bipyrazol-3-yl) methanolL5, and 5,5′-diphenyl-3,3′-bipyrazoleL6, are reported and studied for their catecholase activities at ambient conditions, the reaction rate depends on four parameters: The nature of the carbonic chain bounded to the pyrazole ring, the nature of counter anion, the concentration of ligand and the nature of solvent. The highest rate activity is given by complex resulting from one equivalent of ligandL4 and two equivalents of Cu(CH3COO)2 in methanol, which equal to 4.440μmolL−1min−1.
Keywords: Pyrazole; Catechol; Pyridylpyrazole; Nitrogen heterocycles; Copper; Oxidation reaction
Oxidative coupling of methane over unsupported and alumina-supported samaria catalysts by Trenton W. Elkins; Helena E. Hagelin-Weaver (pp. 100-114).
Display Omitted► Smallest Sm2O3 nanoparticles yield highest OCM activity per unit weight of catalyst. ► Incipient wetness impregnation using Sm(NO3)3 best method for Sm2O3/Al2O3. ► Sm2O3/n-Al2O3(−)-IM produces the highest yield at 5.6% for supported catalysts. ► Yield per gram of Sm2O3 is higher for Sm2O3/n-Al2O3(−) than Sm2O3 NPs.Being the shortest unsaturated hydrocarbon, ethylene is a valuable feedstock gas for synthesizing longer chain hydrocarbon products. Using the oxidative coupling of methane to produce ethylene and ethane (C2 products) has been studied extensively over the past few decades. In this work, samaria nanoparticles (NPs) and alumina-supported samaria catalysts were prepared using different methods (water/toluene reverse microemulsion, metal-oleate high temperature decomposition, and incipient-wetness impregnation followed by calcination) and various types of alumina supports (high and low surface area nanoparticle alumina [n-Al2O3(+), n-Al2O3(−)] and a porous gamma alumina support [p-Al2O3]). The highest product yields were obtained over Sm2O3 NPs synthesized using the metal-oleate high temperature decomposition and a nitrate precursor. Using a chloride precursor in the preparation of the Sm2O3 NPs resulted in less active and selective catalysts, and should be avoided. While the C2 selectivities were lower over the Sm2O3/Al2O3 catalysts, the yield per gram of Sm2O3 were higher compared with the Sm2O3 NPs. The best supported catalyst was the Sm2O3/n-Al2O3(−) prepared using incipient wetness impregnation of a nitrate precursor, since this leads to the smallest Sm2O3 particles as well as the largest coverage of the acidic Al2O3 support. XRD analysis revealed that high-temperature calcinations form SmAlO3 on the Al2O3-supported catalysts. While this reduced the near surface Sm2O3 concentration, it had beneficial effects as it also lowered the Al2O3 content. Therefore, Al2O3-supported Sm2O3 warrants further investigation, as surface modifications of the Al2O3 can reduce its acidity and lead to higher C2 selectivities in the oxidative coupling of methane over these catalysts.
Keywords: Samarium oxide nanoparticles; Alumina-supported samaria; Methane coupling activity and selectivity; XRD; XPS
Plasma-chemically brominated single-walled carbon nanotubes as novel catalysts for oil hydrocarbons aerobic oxidation by Eldar Zeynalov; Joerg Friedrich; Asmus Meyer-Plath; Gundula Hidde; Lyatif Nuriyev; Aygun Aliyeva; Yutta Cherepnova (pp. 115-118).
Display Omitted► Carbon nanotubes were plasma brominated (6at%). ► Strong acceleration of the model oxidation of cumene. ► Higher catalytic activity than industrial catalysts.Brominated single-walled carbon nanotubes [(Br) n-SWCNT) produced by the plasma-chemical technique were involved in the liquid-phase process of hydrocarbons aerobic oxidation. The significant catalytic effect of the (Br) n-SWCNT was revealed at first by the cumene initiated model oxidation and then in experiments on profound aerobic oxidation of petroleum naphthenic fraction derived from the commercial Azerbaijan (Baku) oils blend diesel cut. The ability of (Br) n-SWCNT to accelerate the aerobic oxidation of the hydrocarbons was found out for the first time. Obviously this phenomenon originates from the peculiarities of electronic configuration of the (Br) n-CNT patterns. The plausible mechanism of (Br) n-SWCNT catalytic action is inclined to the formation of reactive oxygen species. The catalytic activity of (Br) n-SWCNT markedly exceeds the activity of the industrial catalysts, manganese salt of indigenous petroleum acids, used for the liquid phase petroleum hydrocarbons oxidation process.
Keywords: Brominated carbon nanotubes; Plasma-chemical technique; Model cumene oxidation; Oxidation rate; Oxidation catalysts; Oil hydrocarbons liquid-phase oxidation; Manganese naphthenate; Synthetic petroleum acids
Gold nanoparticles immobilized on lipoic acid functionalized SBA-15: Synthesis, characterization and catalytic applications by Narani Anand; Pochamoni Ramudu; Kannapu Hari Prasad Reddy; Kamaraju Seetha Rama Rao; Bharatam Jagadeesh; Vemulapalli Sahithya Phani Babu; David Raju Burri (pp. 119-126).
Display Omitted► SBA-LAG is a new hexagonally ordered mesoporous heterogeneous catalyst. ► Lipoic acid spacer acts as anchoring point to SBA-15 and capping agent for AuNPs. ► SBA-LAG is a solvent-free and leaching-free catalyst. ► SBA-LAG is a highly efficient catalyst for propargylamines synthesis. ► SBA-LAG is a stable catalyst and minimizes diffusion limitations.Gold nanoparticles immobilized on lipoic acid functionalized SBA-15 (SBA-LAG) catalyst was synthesized via functionalization of SBA-15 with propylamine followed by tethering of lipoic acid and immobilization of gold nanoparticles. The structural and texctural characteristics of the catalyst have been determined by N2 adsorption–desorption and low-angle XRD. The successive attachment of spacers has been characterized by13C CP-MAS NMR, FT-IR and TG-DTA. The size, shape, surface composition and oxidation state of gold nanoparticles have been determined by XRD, TEM and XPS techniques. SBA-LAG catalyst is found to be an efficient solid catalyst for producing good to excellent yields of propargylamines by condensing three-components such as (i) amine, (ii) aldehyde and (iii) alkyne in one-pot under solvent-free conditions.
Keywords: SBA-15; Lipoic acid; Gold nanoparticles; Propargylamines; Solvent-free system
Liquid phase chemo-selective catalytic hydrogenation of furfural to furfuryl alcohol by Rajesh V. Sharma; Umashankar Das; Ramaswami Sammynaiken; Ajay K. Dalai (pp. 127-136).
Display Omitted► A Cu–Cr based catalyst was modified with the addition of Zn and Zr as promoters. ► Addition of Zn increases the activity of the catalyst. ► Selectivity of the furfuryl alcohol is increased by the addition of Zr. ► The apparent activation energy is found to be 24.4kcal/mol. ► Catalyst is recyclable.Novel Cu:Zn:Cr:Zr based catalysts were developed for the hydrogenation of furfural to furfuryl alcohol. Physio-chemical characterizations of the catalysts were performed by using XRD, BET, FTIR, TPR, NH3-TPD, ICP-MS, SEM, TEM, CO-chemisorption, and XANES techniques. Among all the catalysts prepared, the catalysts Cu(3):Zn(2):Cr(1):Zr(3) and Cu(3):Zn(2):Cr(1):Zr(4), referred as Cat-C and Cat-D, respectively are the best ones to demonstrate high activity and selectivity profile. Cat-C and Cat-D exhibited 100% conversion and 96% selectivity at 170±2°C and 2MPa of hydrogen pressure. The role of constituent metals in the catalyst was delineated. Incorporation of Zn increases the activity for furfural conversion whereas Zr contributes significantly to the selectivity of furfuryl alcohol. It was also found that Zr loading not only increases the acidity of the catalyst but also helps in the dispersion of metallic Cu. The particle size of metallic Cu was found to be in the range of 17–19nm as confirmed by TEM, XRD and CO chemisorption techniques. XANES analysis confirmed the presence of copper in Cu0 and Cu2+ oxidation states in Cat-C (freshly reduced) and Cat-C (fresh), respectively. Hydrogenation of furfural to furfuryl alcohol follows a pseudo-first order reaction with an the apparent activation energy of 24.4kcal/mol. Cat-C was recycled at least 4 times for the hydrogenation of furfural with no loss of activity and selectivity when compared to the fresh catalyst.
Keywords: Furfural; Furfuryl alcohol; Heterogeneous catalyst; Hydrogenation
Temperature effects in benzene alkylation with ethane into ethylbenzene over a PtH-MFI bifunctional catalyst by Kae S. Wong; Tanya Vazhnova; Sean P. Rigby; Dmitry B. Lukyanov (pp. 137-144).
Display Omitted► Coupling of ethane dehydrogenation (1) and benzene alkylation with ethene (2). ► At temperatures below ∼370°C formation of ethylbenzene is limited by step (1). ► At temperatures above ∼410°C formation of ethylbenzene is limited by step (2). ► Excessive formation of ethene above 410°C leads to side products and deactivation. ► Optimum reaction temperature range: 370–410°C.Benzene alkylation with ethane into ethylbenzene (EB) over a PtH-MFI bifunctional catalyst was thoroughly studied at six different temperatures between 290 and 490°C. Our work demonstrates that temperature affects in a different way the thermodynamic equilibrium of two major reaction steps: (i) ethane dehydrogenation into ethene over Pt sites and (ii) benzene alkylation with ethene over acid sites. This, in turn, leads to significant differences in the product distribution and catalyst performance at different temperatures. It is shown that with increasing temperature ethane dehydrogenation is highly accelerated, while the EB formation rate increases in much lesser extent. As a consequence, high concentration of ethene is observed at high temperatures (450–490°C), while the maximum concentrations of EB are very similar at all temperatures. Ethene, which is formed in excess at high temperatures, is converted via oligomerization and cracking steps into higher alkenes that alkylate benzene (or aromatic products). These alkylation reactions are followed by cyclization and dehydrogenation steps leading to formation of polyaromatics (coke precursors) and subsequent catalyst deactivation. On the other hand, at lower temperatures (290–410°C) ethene reacts preferably with benzene forming EB. Hence, side reactions are suppressed and high EB selectivity and catalyst stability are observed at these temperatures. Based on the analysis of the catalyst activity, selectivity and stability, it is concluded that 370–410°C can be considered as the optimum temperature range for the direct benzene alkylation with ethane into EB. Further improvement of the process may be achieved by selective removal of hydrogen from the reactor and by optimization of the ethane/benzene ratio in the feed.
Keywords: Alkylation; Dehydrogenation; Bifunctional catalysis; Zeolite
Phospha-Michael addition of diethyl phosphite to α,β-unsaturated malonates catalyzed by nano γ-Fe2O3-pyridine based catalyst as a new magnetically recyclable heterogeneous organic base by Sara Sobhani; Mahboobeh Bazrafshan; Amin Arabshahi Delluei; Zahra Pakdin Parizi (pp. 145-151).
Display Omitted► A pyridine based catalyst supported on γ-Fe2O3 nanoparticles was synthesized. ► It was used as a recyclable catalyst for the synthesis of β-phosphonomalonates. ► β-phosphonomalonates were obtained in good to high yields. ► In this method, catalyst separation was easily performable by a magnetic bar.Nano γ-Fe2O3-pyridine based catalyst as a new magnetically recyclable heterogeneous organic base was synthesized. The synthesized odorless pyridine based catalyst was used as a new catalyst for the efficient synthesis of β-phosphonomalonates by the reaction of diethyl phosphite with α,β-unsaturated malonates. The catalyst was easily isolated from the reaction mixture by a magnetic bar and reused at least 10 times without significant degradation in the activity.
Keywords: β-Phosphonomalonates; Nanoparticles; Heterogeneous catalyst; Pyridine; Iron oxide
Ethylene oligomerization using nickel-β-diimine hybrid xerogels produced by the sol–gel process by Enéderson Rossetto; Marcela Caovilla; Daniel Thiele; Roberto F. de Souza; Katia Bernardo-Gusmão (pp. 152-159).
Hybrid silica was synthesized by the sol–gel method and subsequently complexed with metal to form a heterogenized nickel-β-diimine/silica complex, which was employed in ethylene-oligomerization reactions.Display Omitted► Three β-diimine ligands and their corresponding nickel-complexes were synthesized. ► Hybrid silica containing β-diimine groups were prepared by sol–gel process. ► Hybrid silica were complexed with nickel to form heterogenized nickel-complex. ► Ethylene oligomerization using nickel-β-diimines was described. ► Ligands nature were correlated with the catalytic activity and selectivity.Nickel-β-diimine complexes have been used as homogeneous- and heterogeneous-phase oligomerization catalysts. The following complexes have also been heterogenized on silica using the sol–gel method: 1,5- bis(phenyl)-pentanediimine-dibromonickel(II) (A), 1,5- bis(2,6-dimethylphenyl)-2,4-pentanediimine-dibromonickel(II) (B) and 1,5- bis(2,4,6-trimethylphenyl)-2,4-pentanediimine-dibromonickel(II) (C). The synthesis of the xerogels was performed employing 3-chloropropyltrimethoxysilane (CPTMS), tetraethylorthosilicate (TEOS) and HF. The hybrid β-diimine/silica materials are used in combination with ethylaluminum sesquichloride (EASC) and have been shown to be outstanding ethylene oligomerization catalyst systems. Under mild reactions conditions, the homogeneous and heterogenized catalysts had high turnover frequencies (between 1800 and 210,000h−1). The best selectivities were obtained with the heterogenized catalysts, which give 100% of C4 fraction with 1-butene selectivities of up to 91%.
Keywords: Oligomerization; Ethylene; β-Diimine; Xerogel; Sol–gel process; Organic–inorganic hybrid materials
Polyethylene glycol (PEG-200)-promoted sustainable one-pot three-component synthesis of 3-indole derivatives in water by Leilei Wang; Manna Huang; Xinhai Zhu; Yiqian Wan (pp. 160-163).
Display Omitted► A sustainable protocol for synthesis of 3-indole derivatives was established. ► Reaction of indoles, aldehydes, malononitrile was promoted by PEG-200 in water. ► The metal catalysts such as copper or indium are not required in this protocol. ► The reaction media can be reused four times without erosion of the yield. ► The target products often can be easily isolated by simple filtration.A sustainable three-component reaction of indoles, aldehydes, and malononitrile in water promoted by polyethylene glycol (PEG-200) afforded 3-indole derivatives in good to excellent yields.
Keywords: Green chemistry; Multicomponent reaction; Aldol reaction; Michael addition
Tetramethylguanidine–silica nanoparticles as an efficient and reusable catalyst for the synthesis of cyclic propylene carbonate from carbon dioxide and propylene oxide by Farook Adam; Muazu Samaila Batagarawa (pp. 164-171).
Display Omitted► Silica from rice husk ash was functionalized with tetramethylguanidine. ► The catalyst consisted of nanoparticles. ► The catalyst aided the cycloaddition of CO2 to propylene oxide. ► 98% selectivity toward propylene carbonate was achieved with the catalyst. ► Catalyst was recycled several times and found to be stable and efficient.Tetramethylguanidine covalently bonded to silica was found to be an efficient and recyclable catalyst for the synthesis of propylene carbonate (PC) from propylene oxide (PO) and carbon dioxide. The catalyst was prepared, first by the coupling of 3-(chloropropyl)triethoxy silane with silica from rice husk ash (RHA), to form 3-chloropropyl silica (RHACCl). This was later grafted with tetramethylguanidine molecule to form a solid base catalyst (RHAPrTMG). The surface morphology analyzed by TEM, revealed the presence of spherical nanoparticles with an average size of 19.62nm. The13C solid state NMR indicated the presence of 5 sets of carbon atoms in the structure. A conversion of 92% was achieved under the optimized reaction conditions (130°C, 5.0MPa, 8h), with a propylene carbonate selectivity of ca. 98%. The catalyst can be easily recovered by filtration and reused for at least four times without appreciable loss of its catalytic activity.
Keywords: Tetramethylguanidine; Silica–guanidine nanoparticles; Carbon dioxide; Propylene oxide; Propylene carbonate