Direct synthesis, characterization and catalytic performance of Al-SBA-15 mesoporous catalysts with varying Si/Al molar ratios

Through a directly hydrothermal process and utilizing Pluronic P123 triblock polymer (EO₂₀PO₇₀EO₂₀, M_av = 5800) as a template, Al-SBA-15 mesoporous materials have been prepared with different Si/Al molar ratios. The materials were characterized by XRD, ICP-OES, SEM, TEM, Py FT-IR, N₂ adsorption–desorption and NH₃-TPD techniques. Meanwhile, the catalytic performance of the Al-SBA-15 materials was investigated through Friedel–Crafts alkylation of 2,4-ditert-butyl-phenol with cinnamyl alcohol. Characterization results showed that the catalysts contain a variety of acid sites whose contents vary in a systematic manner with various Si/Al molar ratios of the materials, and have a higher catalytic activity in the alkylation reaction of phenol with tert-butanol. It was found that the Al-SBA-15 samples with good mesoporous structure are highly reusable preserving most of their catalytic activity after five cycles.     

Synthesis and characterization of mesoporous Mn/Al-SBA-15 and its catalytic activity for NO reduction with ammonia

Al-SBA-15 was prepared by one-step hydrothermal synthesis method, and was characterized by X-ray diffraction, N₂-adsorption, transmission electron microscope and Fourier infrared spectra of chemisorbed pyridine (Py-IR). The results showed that Al-SBA-15 had well-ordered hexagonal mesopores. As compared with Si-SBA-15, Al-SBA-15 had thicker pore wall, higher surface area, and stronger Lewis acidity. Due to the stronger Lewis acidity, Mn/Al-SBA-15 catalyst prepared by impregnation showed better activity than Mn/Si-SBA-15 in the selective catalytic reduction of NO by NH₃.     

GC/EI-MS Determination of the Diastereomer Distribution of Phytanic Acid in Food Samples

Phytanic acid (3,7,11,15-tetramethylhexadecanoic acid) is a branched-chain fatty acid, produced by bacteria by means of oxidation and biohydrogenation of the chlorophyll side chain phytol (3,7R,11R,15-tetramethylhexadec-2-en-1-ol). The later reaction generates to a new stereogenic center on C-3 which can be both 3R- or 3S-configured. Thus, two diastereomers (3S,7R,11R,15- and 3R,7R,11R,15-phytanic acid) are naturally produced. In this study we examined the diastereomer composition of phytanic acid in terrestrial and marine food samples. Phytanic acid was transferred into its methyl ester which was analyzed by GC/MS in the selected ion monitoring mode. The first eluted diastereomer in the samples was tentatively identified as 3S,7R,11R,15-phytanic acid. The marine samples were clearly dominated by 3S,7R,11R,15-phytanic acid whose abundance was higher in marine mammals than in fish. Milk from one organic cow collected over a period of 30 days showed lower proportions of 3S,7R,11R,15-phytanic acid than milk from one cow raised with conventional feed. The difference between organic and conventional dairy products (cheese and butter) was not as pronounced as in milk. Milk samples from other mammals (goat, sheep, mare, camel, moose, and human) also showed an excess of 3S,7R,11R,15-phytanic acid except for camel and moose milk.     

Pyrolysis and co-pyrolysis of Laminaria japonica and polypropylene over mesoporous Al-SBA-15 catalyst

The catalytic co-pyrolysis of a seaweed biomass, Laminaria japonica, and a typical polymer material, polypropylene, was studied for the first time. A mesoporous material Al-SBA-15 was used as a catalyst. Pyrolysis experiments were conducted using a fixed-bed reactor and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). BET surface area, N₂ adsorption-desorption isotherms, and NH₃ temperature programmed desorption were measured to examine the catalyst characteristics. When only L. japonica was pyrolyzed, catalytic reforming slightly increased the gas yield and decreased the oil yield. The H₂O content in bio-oil was increased by catalytic reforming from 42.03 to 50.32 wt% due to the dehydration reaction occurring on the acid sites inside the large pores of Al-SBA-15. Acids, oxygenates, mono-aromatics, poly aromatic hydrocarbons, and phenolics were the main components of the bio-oil obtained from the pyrolysis of L. japonica. Upon catalytic reforming over Al-SBA-15, the main oxygenate species 1,4-anhydro-d-galactitol and 1,5-anhydro-d-manitol were completely removed. When L. japonica was co-pyrolyzed with polypropylene, the H₂O content in bio-oil was decreased dramatically (8.93 wt% in the case of catalytic co-pyrolysis), contributing to the improvement of the oil quality. A huge increase in the content of gasoline-range and diesel-range hydrocarbons in bio-oil was the most remarkable change that resulted from the co-pyrolysis with polypropylene, suggesting its potential as a transport fuel. The content of mono-aromatics with high economic value was also increased significantly by catalytic co-pyrolysis.     

La-SO42-改性Al-SBA-15催化剂的制备与应用

以Al-SBA-15为载体,采用浸渍法制备La-SO₄^2-/Al-SBA-15催化剂,考察催化剂的制备条件。结果表明,La³⁺浓度为0.03 mol·L^-1和500 ℃焙烧3 h制得的La-SO₄^2-/Al-SBA-15在催化乙酸正丁酯反应中具有良好的催化性能。将制得的La-SO₄^2-/Al-SBA-15催化剂应用于乙酸正丁酯合成,结果表明,在n(冰乙酸)∶n(正丁醇)=1∶1.2、催化剂用量为冰乙酸质量的6%和反应3.5 h条件下,酯化率达97.85%。     

Hydrocracking of heavy oil using zeolites Y/Al-SBA-15 composites as catalyst supports

A series of Y/Al-SBA-15 composites were prepared by a two-step synthesis procedure in mild acidic medium. The materials were characterized by powder X-ray diffraction (XRD), N₂ sorption isotherms and TEM techniques. Catalytic cracking of cumene and 1,3,5-tri-isopropylbenzene was carried out as the probing reactions on these composites. The XRD results showed that these materials are composites of Al-SBA-15 and Y zeolite. N₂ sorption isotherms and TEM displayed that these composites were abundant in micropores and mesopores. At the same time, the mesopores may communicate with the␣micropores in some domains, which may result in the high catalytic activities of Y/Al-SBA-15 composites for the␣cracking of both small-molecule (cumene) and large-molecule (1,3,5-tri-isopropylbenzene) hydrocarbons. The existence of mesopores may also make the acid sites easily accessible for reactants. Catalysts of W–Ni supported on Y/Al-SBA-15 and modified Y zeolites with mesopores were prepared by impregnation method, and the hydrocracking of heavy oil was performed on these catalysts. The catalyst using zeolite Y/mesoporous Al-SBA-15 composites as support gave higher yield of diesel compared to the catalysts using modified zeolite Y as support. In addition, the higher aromatics potential of heavy naphtha and the significantly lower BMCI (U.S. Bureau of Correlation Index) of tail oil revealed Y/Al-SBA-15 composite catalyst possessed integrated performance in the hydrocracking of heavy oil. These results proved that the combination of Y zeolites and mesoporous Al-SBA-15 plays a great role in improving the performance of catalysts for hydrocracking heavy oils.     

Bifunctional Pd/Al-SBA-15 catalyzed one-step hydrogenation–esterification of furfural and acetic acid: A model reaction for catalytic upgrading of bio-oil

Al-SBA-15 supported palladium bifunctional catalysts were evaluated for one-step hydrogenation–esterification (OHE) of furfural and acetic acid as a model reaction for bio-oil upgrading. Experimental results show that it is viable to convert these unstable constituents of bio-oil to esters and alcohols through this simple and effective OHE reaction. The results of NH₃–TPD and catalytic performances show that Al-SBA-15 with medium ratio of Si/Al favors the OHE reaction between furfural and acetic acid. It is noteworthy that there is a synergistic effect between the metal sites and the acid sites over composite bifunctional catalyst of 5%Pd/Al-SBA-15 for the OHE reaction.     

Ethylene/hexene living copolymerization and ethylene/methyl 10-undecenoate copolymerization by titanium complexes bearing phenoxy-phosphine or thiophenoxy-phosphine ligands

Several non-metallocene-type titanium(IV) complexes containing phenoxy-phosphine or thiophenoxy-phosphine ligands of type, (2-R₁-4-R₂-6-PPh₂-C₆H₂X)₂TiCl₂ (2a: X = O, R₁ = R₂ = t-Bu; 2b: X = O, R₁ = R₂ = cumyl; 2c: X = S, R₁ = SiMe₃, R₂ = H) have been synthesized by treating TiCl₄ with the corresponding ligands 2-R₁-4-R₂-6-PPh₂-C₆H₂XH in the presence of n-BuLi. The complexes 2a-c were investigated as the catalysts for ethylene with 1-hexene and/or polar alkenes copolymerizations. The catalytic activity and the comonomer incorporation were highly dependent upon catalyst and reaction conditions employed. Among these complexes, 2a can not only promote ethylene/1-hexene living copolymerization at room temperature, but also can utilize ethylene with methyl 10-undecenoate copolymerization.     

(R,R)-salen/salan-based polymer fluorescence sensors for Zn detection

(R,R)-salen-based polymer fluorescence sensor P-1 could be synthesized by the polymerization of 5,5′-(isoquinoline-5,8-diylbis(ethyne-2,1-diyl))-bis(3-tert-butyl-2-hydroxybenzaldehyde) (M-1) with (R,R)-1,2-diaminocyclohexane (M-2) via nucleophilic addition-elimination reaction, and (R,R)-salan-based polymer sensor P-2 could be obtained by the reduction reaction of P-1 with NaBH₄. The fluorescence response behaviors of two chiral polymers P-1 and P-2 on Zn²⁺ were investigated by fluorescence spectra. The fluorescence intensities of P-1 and P-2 can exhibit gradual enhancement upon addition of Zn²⁺. Compared with other cations, such as Na⁺, K⁺, Mg²⁺, Ca²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Ag⁺, Cd²⁺, Cr³⁺ and Pb²⁺, Zn²⁺ can lead to the pronounced fluorescence enhancement as high as 22.8-fold for P-1 and 3.75-fold for P-2, respectively. The results show that P-1 and P-2 incorporating (R,R)-salen/salan moieties as receptors in the polymer main chain backbone can exhibit high sensitivity and selectivity for Zn²⁺ detection.     

Identification of Sex Pheromone Components of Blueberry Spanworm Itame argillacearia (Lepidoptera: Geometridae)

Blueberry spanworm, Itame argillacearia (Packard), is an important defoliator of lowbush (syn. ‘wild’) blueberry, Vaccinium angustifolium Aiton, in north-eastern North America. The goal of the present study was to identify the female I. argillacearia sex pheromone, which could be used in traps for monitoring or mass-trapping this pest. Gas chromatography/mass spectrometry (GC/MS) and electroantennogram (EAG) recordings of sex pheromone gland extracts, in combination with chemical synthesis, a Y-tube olfactometer study and field experiments confirmed (2R,3S)-2-ethyl-3-((Z,Z)-tridecadi-2,5-enyl) oxirane (hereafter (Z,Z)-(3R,4S)-3,4-epoxy-6,9-heptadecadiene) and (Z,Z,Z)-3,6,9-heptadecatriene as female-produced sex pheromone components. (Z,Z)-(3R,4S)-3,4-Epoxy-6,9-heptadecadiene elicited a response from male I. argillacearia antennae during EAG recording, and in the Y-tube olfactometer tests males did not discriminate between a live female and (Z,Z)-(3R,4S)-3,4-epoxy-6,9-heptadecadiene. Field-trapping experiments showed that a blend of (Z,Z)-(3R,4S)-3,4-epoxy-6,9-heptadecadiene and (Z,Z,Z)-3,6,9-heptadecatriene was more attractive to male moths than (Z,Z)-(3R,4S)-3,4-epoxy-6,9-heptadecadiene alone.     

Homo- and R/S-copolymerizations of chiral methylpropargyl esters carrying pyrene moieties, and optical properties of the formed polymers

Pyrene-functionalized chiral methylpropargyl esters, (R)-3-butyn-2-yl-1-pyrenebutyrate [(R)-1], (S)-3-butyn-2-yl-1-pyrenebutyrate [(S)-1], (R)-3-butyn-2-yl-1-pyrenecarboxylate [(R)-2], and 3-butyn-2-yl-1-pyrenecarboxylate [(R,S)-2] were polymerized with (nbd)Rh⁺[η⁶-C₆H₅B⁻(C₆H₅)₃] to obtain the corresponding polymers with moderate molecular weights (M_n: 10?500-66?500) in good yields (82-97%). All the polymers were soluble in CHCl₃, CH₂Cl₂, and THF. The polarimetric and CD spectroscopic data indicated that poly[(R)-1], poly[(S)-1], and poly[(R)-2] existed in a helical structure with predominantly one-handed screw sense in these solvents. The helical structure of poly[(R)-1] and poly[(S)-1] was stable upon heating and addition of MeOH, while that of poly[(R)-2] changed upon MeOH addition. The copolymerization of (R)-1 with (S)-1 was also conducted to obtain the copolymers satisfactorily. Poly[(R)-1], poly[(S)-1], and poly[(R)-2] emitted fluorescence smaller than the corresponding racemic copolymers. The fluorescence intensity was tuned by the addition of MeOH to THF solutions of the polymers.     

Zirconium phosphonate immobilized chiral amino alcohol for heterogeneous enantioselective addition of diethylzinc to benzaldehyde

The chiral (1R,2S)-(−)-2-amino-1,2-diphenylethanol and (1S,2R)-(+)-2-amino-1,2-diphenylethanol had been immobilized on the layered frame of zirconium phosphate to obtain zirconium phosphonates (1R,2S)-(−)-4a and (1S,2R)-(+)-4b. The enantioselective addition of Et₂Zn to benzaldehyde using zirconium phosphonates (1R,2S)-(−)-4a and (1S,2R)-(+)-4b as heterogeneous catalysts yielded secondary alcohol in 80.1% yield and e.e. values of up to 54.3%, which was only 7.6% e.e. lower than that using the corresponding ligands (1R,2S)-(−)-2a and (1S,2R)-(+)-2b as homogeneous catalysts. The zirconium phosphonates (1R,2S)-(−)-4a and (1S,2R)-(+)-4b were characterized by IR, SEM, XRD and TG analysis. SEM and XRD data showed that the catalysts (1S,2R)-(+)-4b and (1R,2S)-(−)-4a were in aggregate and mesopore structure with the same interlayer spacing 2.48 nm and pore diameter 5.6 nm.     

CRN synthesis of β-SiAlON from a nanocomposite precursor of mesoporous silica–alumina (Al-SBA-15) with poly 4-vinyl pyridine

This paper reports the use of a nanocomposite precursor of mesoporous silica?Calumina (Al-SBA-15) with poly 4-vinyl pyridine (P4VP) to synthesise ??-SiAlON by carbothermal reduction and nitridation under N₂ at 1,450?°C. Small-angle XRD, SEM/TEM, ²⁹Si and ²⁷Al MAS-NMR and BET specific surface area measurements of the Al-SBA-15 and P4VP/Al-SBA-15 composite confirmed the mesoporous structure and the presence of Al in the precursors, while surface polymerization of the Al-SBA-15 was indicated by ²⁹Si-NMR. Firing the nanocomposite in a N₂ atmosphere forms the nitride phase, depending on the amount and type of carbon present, on the surface area of the precursor. Even with these precursors of high surface area, the present result was obtained using approximately twice the stochiometric amount of carbon.     

Ca–O Binding of Poly[1-carboxylate-2-(N-t- butylcarbamoyl)ethylene-alt-ethylene] and Calcium Carbonate Composites

A novel poly(carboxylate) ligand was synthesized as a ligand for a crystalline CaCO₃-organic composite. Poly[1-carboxylate-2-(N-t-butylcarbamoyl)ethylene-alt-ethylene] has a 7-membered ring with an intramolecular NH·O hydrogen bond between the carboxylate group and the neighboring amide NH proton in the anionic carboxylate form. The configuration of the polymer ligand was estimated with polymer repeat-unit models, (S,S)- or (R,R)-2-(N-t-butylcarbamoyl)-cyclohexanecarboxylic acid ((S,S)- or (R,R)-TBCA) and (S,R)- 2-(N-t-butylcarbamoyl)-cyclohexanecarboxylic acid ((S,R)-TBCA). The proton NMR spectum of the carboxylate anion of (S,S)- or (R,R)-TBCA exhibits a non-hydrogen bonded NH signal at 7.31 ppm in Me₂SO-d ₆. (S,R)-TBCA shows a strongly NH·O hydrogen-bonded NH signal at 8.50 ppm. The observation of one strongly NH·O hydrogen bonded NH signal at 11.3 ppm indicates that the polymer anion has a threo-form in the zigzag polymer main chain. Moreover, a polymer ligand-CaCO₃ composite was synthesized. The composite was characterized by ¹³C cross polarization/magic angle spinning (CP/MAS) and scanning electron microscopy (SEM). The polymer ligand stabilizes the Ca–O (carboxylate) bond in the CaCO₃ composite. This prevents dissociation due to pK_a shifts of the NH·O hydrogen bond and controls the crystal growth toward metastable vaterite.     

Biocatalytic separation of (R, S)-1-phenylethanol enantiomers and fractionation of reaction products with supercritical carbon dioxide

The continuous kinetic resolution of (R, S)-1-phenylethanol via enzymatic transesterification was chosen as a benchmark reaction for the study of a complete reaction/separation process using supercritical carbon dioxide. Phase equilibrium data for binary and ternary systems was acquired as a starting point to determine the best conditions of operation. Total conversion of the (R)-isomer of the alcohol was achieved using a 10% molar excess of vinyl laurate. Three separators operating at given temperatures and pressures allowed the recovery of (S)-1-phenylethanol with a purity of 86%. The phase equilibrium data obtained indicates that an additional separation step should allow the recovery of both (S)-1-phenylethanol and (R)-1-phenylethylaurate with over 95% purity. Due to the low solubilities of the target compounds, CO₂ from the outlet gas stream of the last separator must be recycled to ensure the technical viability of the integrated reaction/separation of (R, S)-1-phenylethanol.     

A novel two-dimensional chiral coordination polymer: bis(S-(-)-lactate)zinc(II)

The synthesis and X-ray characterization of a novel chiral two-dimensional condensed metal–organic coordination polymer, bis(S-(-)-lactate)zinc(II) (1), are reported. Its crystal structure determination shows that a chiral cavity with approximate dimensions of 5.4×5.4 Ų is present. Crystallographic data for 1, C₆H₁₀O₆Zn, monoclinic P2₁, a=7.4440(15), b=7.4550(15), c=7.4550(15) Å, β=95.73(3)°, V=429.48(15) ų, R₁=0.0272, wR₂=0.0751.     

Two novel glucosylceramides from gonads and body walls of the Patagonian starfish Allostichaster inaequalis

From the water-insoluble lipid fraction of the chloroform/methanol/water extract of the gonads and body walls of the Patagonian starfish Allostichaster inaequalis, two new glucosylceramides (4 and 7) were isolated together with the known phalluside-1 (1) and two glucosylceramides (2 and 3) previously isolated from the starfish Cosmasterias lurida. The new compounds were characterized as (2S,3R,4E,8E,10E)-1-(β-d-glucopyranosyloxy)-3-hydroxy-2-[(R)-2-hydroxy-15-tetracosenoyl] amino-4,8,10-octadecatriene (4) and (2S,3R,4E,15Z)-1-(β-d-glucopyranosyloxy)-3-hydroxy-2-[(R)-2-hydroxyhexadecanoyl] amino-4,15-docosadiene (7) by means of spectroscopic and chemical methods.     

Etude de la reduction electrochimique de systemes heterocycliques oxygenes insatures.—III. Reduction d'acyl-2 dihydro-5,6 4H pyrannes et de chlor acyl-2 dihydro-5,6 4H pyrannes

The macro-scale electrochemical reduction of the 3-chloro-2-acyl-5.6-dihydro-4H-pyrans, on mercury cathode in aqueous medium, is a good method to obtain in quantity the 2-acyl-5.6-dihydro-4H- pyrans, after elimination of the halogen group.The reduction of the 2-acyl-5.6-dihydro-4H-pyrans is also selective in acidic medium and besides very small amounts of dimeric products, we can get 2-acyltetrahydropyrans in good yields. In basic medium selectivity is good, and 5.6-dihydro-4H-pyran-2-yl carbinols are obtained only if R, in the acyl group, has a positive Taft's coefficient (R = C₆H₅, Ch₂C₆H₅). When R has an electrodonating effect (R = CH₃, C₂H₅), we have got a mixture of saturated ketone and ethylenic alcohol, where the last is the most important.Polarography and curves E$\text{1}\text{2}$  f(pH) give some information about intemediary species.     

Diesel-like hydrocarbons obtained by direct hydrodeoxygenation of sunflower oil over Pd/Al-SBA-15 catalysts

Hydrodeoxygenation of sunflower oil was performed in an autoclave over 5.0 wt.% Pd/Al-SBA-15 (Si/Al molar ratios from 22 to 300) and Pd/HZSM-5(22). The effects of acidity of the catalysts and the reaction temperatures on the activity of the catalysts were investigated. Pd/Al-SBA-15(Si/Al = 300) showed a high activity as 74.4% liquid yield and 72.9% C15–C18 diesel-like hydrocarbons yield at 250 °C. At 300 °C, the higher activity over Pd/Al-SBA-15(Si/Al = 50, 100 and 300) catalysts compared with that over Pd/Al-SBA-15(22) and Pd/HZSM-5(22) indicated that strong acidity of the catalysts was not favorable for converting sunflower oil into C15–C18 diesel-like hydrocarbons at a high temperature.     

Detection of the First Epoxyalcohol Synthase/Allene Oxide Synthase (CYP74 Clan) in the Lancelet (Branchiostoma belcheri,Chordata)

The CYP74 clan cytochromes (P450) are key enzymes of oxidative metabolism of polyunsaturated fatty acids in plants, some Proteobacteria, brown and green algae, and Metazoa. The CYP74 enzymes, including the allene oxide synthases (AOSs), hydroperoxide lyases, divinyl ether synthases, and epoxyalcohol synthases (EASs) transform the fatty acid hydroperoxides to bioactive oxylipins. A novel CYP74 clan enzyme CYP440A18 of the Asian (Belcher’s) lancelet (Branchiostoma belcheri, Chordata) was biochemically characterized in the present work. The recombinant CYP440A18 enzyme was active towards all substrates used: linoleate and α-linolenate 9- and 13-hydroperoxides, as well as with eicosatetraenoate and eicosapentaenoate 15-hydroperoxides. The enzyme specifically converted α-linolenate 13-hydroperoxide (13-HPOT) to the oxiranyl carbinol (9Z,11R,12R,13S,15Z)-11-hydroxy-12,13-epoxy-9,15-octadecadienoic acid (EAS product), α-ketol, 12-oxo-13-hydroxy-9,15-octadecadienoic acid (AOS product), and cis-12-oxo-10,15-phytodienoic acid (AOS product) at a ratio of around 35:5:1. Other hydroperoxides were converted by this enzyme to the analogous products. In contrast to other substrates, the 13-HPOT and 15-HPEPE yielded higher proportions of α-ketols, as well as the small amounts of cyclopentenones, cis-12-oxo-10,15-phytodienoic acid and its higher homologue, dihomo-cis-12-oxo-3,6,10,15-phytotetraenoic acid, respectively. Thus, the CYP440A18 enzyme exhibited dual EAS/AOS activity. The obtained results allowed us to ascribe a name “B. belcheri EAS/AOS” (BbEAS/AOS) to this enzyme. BbEAS/AOS is a first CYP74 clan enzyme of Chordata species possessing AOS activity.