Hydrogenation Of Methyl Esters Research Articles

Evaluation of the effect of methanol as an in-situ hydrogen source on the reduction of methyl acetate to ethanol

A process was proposed to hydrogenate methyl acetate to ethanol using methanol as an in-situ hydrogen donor over a Cu/SiO2 catalyst. The catalyst was characterized by XRD, H2-TPR, XPS, and FT-IR, and the structure information of the catalyst was obtained. The effects of CH3OH, H2 and mixed hydrogen source on the hydrogenation of methyl acetate on the same catalyst surface were compared, and it was concluded that methanol was an efficient hydrogen source. Furthermore, the influences of process conditions such as temperature and alcohol/ester ratio on methanol conversion, methyl ester conversion, and ethanol selectivity were investigated. The coupling mechanism was analyzed, that methanol decomposition to obtain in-situ hydrogen for methyl ester hydrogenation on a copper-based catalyst. The results showed that methanol as an in-situ hydrogen source could promote not only the efficient hydrogenation of methyl acetate but also inhibit the transesterification side reaction. At a lower alcohol/ester ratio, 90.9% ethanol selectivity and 82.8% methyl acetate conversion could be obtained using only the unmodified catalyst.

Application of mixed phosphorus/sulfur ligands based on terpenoids in Pd-catalyzed asymmetric allylic substitution and Rh-catalyzed hydrogenation.

A small library of easily prepared diamidophosphite-sulfides based on 1,3-thioether alcohols, primarily of terpenoid nature, was developed. Upon complexation with Pd(II) ions, these hemilabile ligands showed the ability to form both P,S-chelates and complexes with two ligands P-monodentately bonded to the metal. The structures of the ligands and their complexes were determined by 2D NMR spectroscopy and X-ray diffraction. The use of these stereoselectors provided up to 95% ee in the classic Pd-catalyzed asymmetric allylic substitution reactions of (E)-1,3-diphenylallyl acetate with C- and N-nucleophiles and up to 80% ee in the Pd-mediated allylic alkylation of cinnamyl acetate with β-ketoesters. In addition, ee values of up to 90% with quantitative conversion were achieved in the Rh-catalyzed asymmetric hydrogenation of methyl esters of unsaturated acids. The effects of the structural parameters, reaction conditions and ligand-to-metal ratio on the catalytic results are discussed.

SiO2 supported Ni-In intermetallic compounds: Efficient for selective hydrogenation of fatty acid methyl esters to fatty alcohols

Ni/SiO2 and SiO2 supported Ni2In, NiIn and Ni2In3 intermetallic compounds (IMCs) were prepared by the sol-gel method and tested for the selective hydrogenation of methyl esters to fatty alcohols. It was found that the Ni phyllosilicate formed during the sol-gel process leads to high Ni dispersion. In IMCs, the Ni atoms are homogeneously isolated by the In ones and the charge is transferred from In to Ni. In the selective hydrogenation, decarbonylation/decarboxylation dominatingly occur on Ni/SiO2, while SiO2 supported IMCs mainly give fatty alcohols, and the yield of fatty alcohol can reach above 94 %. We suggest that it is the synergetic effect between Ni and In that facilitates the selective hydrogenation to yield fatty alcohols. The catalyst stability was also investigated, and the catalyst deactivation is mainly ascribed to the carbonaceous deposit.

Synthesis and Complexation Studies of Optically Active Aza- and Diazacrown Ethers Containing a Pyrene Fluorophore Unit

Novel enantiopure azacrown [(R,R)-1 and (S,S)-1] and diazacrown [(R,R)-2–(R,R)-4 and (S,S)-2–(S,S)-4] ethers containing a pyrene fluorophore unit and two phenyl groups at their chiral centers were obtained in multistep syntheses. The action of these chemosensors is based on the photoinduced electron transfer (PET) process, thus they show fluorescence enhancement in the presence of protonated primary amines and amino acid esters. Their recognition abilities toward the enantiomers of 1-phenylethylamine hydrogen perchlorate (PEA), 1-(1-naphthyl) ethylamine hydrogen perchlorate (NEA), phenylglycine methyl ester hydrogen perchlorate (PGME), and phenylalanine methyl ester hydrogen perchlorate (PAME) were examined in acetonitrile using fluorescence spectroscopy.

Electronic and vibrational spectroscopic (FT-IR and FT-Raman) investigation using ab initio (HF) and DFT (B3LYP and B3PW91) and HOMO/LUMO/MEP analysis on the structure of l-serine methyl ester hydrogen chloride

The vibrational spectroscopy (Fourier Transform Raman and Infrared spectra) of l-serine methyl ester hydrogen chloride (LHCL) have been recorded and the observed vibrational frequencies are assigned and tabulated. The Gaussian hybrid computational calculations were determined by HF and DFT (B3LYP and B3PW91) methods with 6–31++G(d,p) and 6–311++G(d,p) as basis sets. The mulliken and natural charge in the functional group has the maximum magnitude of 0.305 and 0.498 among the hydrogen atoms present in the compound and here, the entire hydrogen atoms exhibit a net positive charge. The change of structure of amino acid due to the addition of subsequent substitutions of methyl, ethyl, carboxylic and hydroxyl chain is investigated. It plays a vital role in the production of different pharmaceutical and cosmetics industries.13C NMR and 1H NMR were calculated by using the gauge independent atomic orbital (GIAO) method with the B3LYP methods and the 6-311 + G(d,p) basis set and nuclear magnetic resonance chemical shifts related to TMS were compared. A study on the optoelectronics properties: absorption wavelengths, excitation energy, oscillator strength, dipole moment and FMO were executed by the HF and DFT methods. UV–Visible spectrum of the present compound is recorded in the region is 200–400 nm and the electronic properties HOMO and LUMO energies are deliberated by TD-DFT method. The polarizability, anisotropy, dipole moment and first order hyperpolarizability of the molecule have been discussed.

Low trans-isomers formation in the aqueous-phase Pt/TPPTS-catalyzed partial hydrogenation of methyl esters of linseed oil

Very low formation of both undesired products namely trans-C18:1 esters and the fully saturated methyl stearate (MS) with high catalytic activities (TOF=6820h−1) under mild reaction conditions have been achieved by water-dispersible platinum(0) nanoparticle catalysts stabilized by TPPTS ligands and the zwitterionic phospholipid surfactant lecithin in the partial hydrogenation of polyunsaturated methyl esters of linseed oil (MELO) into their monounsaturated counterparts in aqueous/organic micellar reactors. The reaction rate was independent of the stirring rate ensuring that mass transfer was not rate determining. The apparent activation energy of the Pt/TPPTS catalyst was calculated and amounts a low value of 17.8kJ/mol. Employing Pt/TPPTS catalysts the starting material MELO possessing an iodine value (IV) of 202 was reduced to IV=85 and contained only 2.4mol% of trans-C18:1 esters. In contrast, in the traditional industrial partial hydrogenation process of soybean oil possessing an IV of 130 reduced over commercial Ni-based catalyst to IV=80 the trans-fats content was∼30mol% whereas with a further reduction to IV=70 to produce all-purpose shortenings the trans-fats level reached a higher value of∼45mol%. In the aqueous-phase catalysis, in the range of 55–70 IVs for the hydrogenated products of MELO the Pt/TPPTS catalysts gave the least amount of trans-C18:1 esters followed by Rh/TPPTS and then by Pd/TPPTS complexes. Interestingly, with Pt/TPPTS catalysts the formation of MS was very low compared with Pd/TPPTS and Rh/TPPTS systems. Over highly active heterogeneous Pt/Al2O3 (5wt.%) catalysts the formation of trans-C18:1 esters was low whereas the content of MS was high (37.7mol%) compared with the very low formation of MS (2.93mol%) with Pt/TPPTS catalysts. Even at a reduction level of IV=72 a sufficient amount of C18:3 esters (2.9mol%) still remained over Pt/Al2O3 catalysts whereas with Pt/TPPTS at IV=70 the conversion of C18:3 esters was quantitative. A recycling experiment at a higher temperature of 80°C showed that the catalytic activity of water-dispersible platinum(0) nanoparticle catalysts stabilized by TPPTS remained high in a consecutive run and possess the potential to be recycled without any loss of catalytic activity. This partial hydrogenation reaction of MELO employing platinum(0) nanoparticle-TPPTS-lecithin-stabilized catalytic systems is an interesting model of a catalytic reaction for studying the selective partial hydrogenation of edible vegetable oils to foodstuffs with very low or zero amounts of both undesired products namely trans-fats and fully saturated fats employing environmentally attractive aqueous/organic two-phase systems.

Supported nickel-rhenium catalysts for selective hydrogenation of methyl esters to alcohols.

The addition of Re to Ni on TiO2 yields efficient catalysts for the hydrogenation of acids and esters to alcohols under mild conditions. Rhenium promotes the formation of atomically dispersed and sub-nanometre-sized bimetallic species interacting strongly with the oxide support.

Synthesis and Enantiomeric Recognition Studies of Optically Active Pyridino-Crown Ethers Containing an Anthracene Fluorophore Unit.

Novel enantiopure pyridino-18-crown-6 ether-based sensor molecules containing an anthracene fluorophore unit were synthesized. Their enantiomeric recognition abilities toward the enantiomers of 1-phenylethylamine hydrogen perchlorate (PhEt), 1-(1-naphthyl)ethylamine hydrogen perchlorate (NapEt), phenylglycine methyl ester hydrogen perchlorate (PhgOMe), and phenylalanine methyl ester hydrogen perchlorate (PheOMe) were examined in acetonitrile using fluorescence spectroscopy. The sensor molecules showed appreciable enantiomeric recognition toward the enantiomers of NapEt, PhEt, and PhgOMe. The highest enantioselectivity was found in the case of crown ether containing isobutyl groups in the macroring and the enantiomers of NapEt. Chirality 28:562-568, 2016. © 2016 Wiley Periodicals, Inc.

Supported Pt-Re catalysts for the selective hydrogenation of methyl and ethyl esters to alcohols

The effect of Re-addition to Pt/TiO2 catalysts for the hydrogenation of carboxylic acids and esters to their corresponding alcohols was investigated. The highest catalytic activity was observed for the materials with Pt:Re molar ratio of 1:2, which allowed for a complete conversion of hexanoic acid under mild conditions. The hydrogenation of esters over the same catalysts was much more difficult. The reactions showed only moderate alcohol yields which also depended strongly on the alkoxy moiety of the ester substrate. The highest yield of ca. 25% was achieved by the hydrogenation of ethyl hexanoate. Conversion of methyl hexanoate was much less efficient. This was attributed to the inhibiting effect of methanol by-product. In situ FTIR spectroscopy suggests that the decarbonylation of methanol and the resulting CO poisoning of the catalyst surface in the course of the reaction is the most likely cause of the low activity of Pt and Pt-Re/TiO2 towards methyl ester hydrogenation.

Preparation and Characterization of Cassiterite (Sno2) and Its Application in the Hydrogenation of Methyl Esters

Tin oxide (IV) or cassiterite obtained by the controlled precipitation method was characterized by different physical and chemical techniques such as TEM, surface area, XRD and RTP for the determination of the morphology, particle size distribution and reduction temperature of the system and then, a pure catalyst and doped with tin (Sn) and nickel (Ni) is employed in the hydrogenation of methyl esters from palm oil. Monitoring the reaction was carried out by gas chromatography and it was found that the Sn-doped system showed a higher activity towards hydrogenation. The products obtained during and after the reaction were analyzed by FT-IR. We found that the hydrogenation of double bonds of the carbon chain was the main reaction, but there were also products resulting from isomerization and surprisingly a small fraction of fatty alcohols with tin-based catalyst Sn/SnO2.

Production of hydrogenated methyl esters of palm kernel and sunflower oils by employing rhodium and ruthenium catalytic complexes of hydrolysis stable monodentate sulfonated triphenylphosphite ligands

This study deals with the hydrogenation of renewable polyunsaturated methyl esters of palm kernel and sunflower oils to the saturated (C18:0) methyl stearate (MS) catalyzed by rhodium and ruthenium complexes modified with hydrolysis stable monodentate sulfonated triphenylphosphite (STPP) ligands under mild reaction conditions in the absence or presence of organic solvents. Superior selectivities up to 95.8mol% of MS were achieved by Rh/STPP catalysts compared with the much lower selectivities (28.0–43.2mol%) of MS obtained by rhodium catalysts modified with conventional triphenylphosphite or triphenylphosphine ligands. The bulkiness of transition metal STPP catalytic system which is in the form of a triisooctylammonium salt offers the possibility of the easy separation of the catalyst from the reaction mixture by means of a membrane. The hydrogenation reaction of the polyunsaturated C18 esters part of palm kernel oil and sunflower oil methyl esters toward the desired saturated product MS is an interesting catalytic reaction because it could acts as a model reaction for studying the hydrogenation of edible vegetable oil triglycerides to hardfats. Hardfats can be further subjected to interesterification reactions with liquid edible vegetable oils to yield foodstuffs with zero amounts of trans-fats. Very recent investigations have questioned whether there really are direct associations between hardfat consumption and a higher cardiovascular disease risk. Furthermore, MS could be used as a starting material of selective heterogeneous catalytic hydrogenolysis reaction of the C18:0 fatty ester to the corresponding saturated C18:0 stearyl alcohol which is an important industrial fatty alcohol.

Aqueous-phase catalytic hydrogenation of methyl esters of Cynara cardunculus alternative low-cost non-edible oil: A useful concept to resolve the food, fuel and environment issue of sustainable biodiesel

Cynara cardunculus a perennial thistle grown wild on marginal lands abandoned from agricultural use without competition with food plants is recently recognized as a low-cost multipurpose energy crop with a high potential for industrial applications inter alia biodiesel production. The selective hydrogenation of polyunsaturated methyl esters of C. cardunculus alternative non-edible oil to their monounsaturated counterparts catalyzed by industrially applied water-soluble Ru/TPPTS complexes [TPPTS=trisulfonated triphenylphosphine, P(C6H4-m-SO3Na)3] in green aqueous media to obtain biodiesel with superior oxidative stability energy and environmental performance at a low pour point could represent an elegant and useful approach to resolve the food, fuel and environment trilemma of sustainable biodiesel production.

Biodiesel production from highly unsaturated feedstock via simultaneous transesterification and partial hydrogenation in supercritical methanol

In this study, a supercritical one-pot process combining transesterification and partial hydrogenation was proposed to test its technical feasibility. Simultaneous transesterification of soybean oil and partial hydrogenation of polyunsaturated compounds over Cu catalyst in supercritical methanol was performed at 320°C and 20MPa. Hydrogenation proceeded simultaneously during the transesterification of soybean oil in supercritical methanol, and hydrogenation occurred during the reaction despite the absence of hydrogen gas. The polyunsaturated methyl esters obtained in the biodiesel were mainly converted to monounsaturated methyl esters by partial hydrogenation. Key properties of the partially hydrogenated methyl esters were improved and complied with standard specifications for biodiesel.

Synthesising unsaturated fatty alcohols from fatty methyl esters using catalysts based on ruthenium and tin supported on alumina

Most promising catalysts for synthesising unsaturated fatty alcohols are based on group 8 metals with a promoter like tin, because the process can be carried out in moderate conditions, and these metals are less toxic than chromium. There have been no reports about the use of this catalyst to date using raw materials like methyl ester blends or evaluation reusing catalysts. This paper presents the hydrogenation of methyl esters from palm oil and commercial methyl oleate with Ru-Sn/Al2O3 catalysts prepared by impregnation, at moderate pressure and temperature (5 MPa and 270°C). Greater selectivity to unsaturated alcohol and the less selectivity to methyl stearate was found for an optimal Sn:Ru=2 ratio. Hydrogenation of palm oil methyl esters with this catalyst produced a mixture of oleyl alcohol, saturated alcohols having 16-18 carbon atoms and heavy esters. Raw material had no great effect on catalyst activity. However, the catalyst showed deactivation through several uses due to decreased catalytic area.

One-pot process combining transesterification and selective hydrogenation for biodiesel production from starting material of high degree of unsaturation

A one-pot process combining transesterification and selective hydrogenation was established to produce biodiesel from hemp (Cannabis sativa L.) seed oil which is eliminated as a potential feedstock by a specification of iodine value (IV; 120g I2/100g maximum) contained in EN 14214. A series of alkaline earth metal oxides and alkaline earth metal supported copper oxide were prepared and tested as catalysts. SrO supported 10wt.% CuO showed the superior catalytic activity for transesterification with a biodiesel yield of 96% and hydrogenation with a reduced iodine value of 113 and also exhibited a promising selectivity for eliminating methyl linolenate and increasing methyl oleate without rising methyl stearate in the selective hydrogenation. The fuel properties of the selective hydrogenated methyl esters are within biodiesel specifications. Furthermore, cetane numbers and iodine values were well correlated with the compositions of the hydrogenated methyl esters according to degrees of unsaturation.

Catalytic hydrogenation of methyl esters of some 1h-pyrazoline-3-carboxylic acids

Hydrogenation over Raney nickel of the methyl ester of 1H-pyrazoline-3-carboxylic acid and also of its 4-phenyl and 5-methoxycarbonyl-substituted analogs, leads respectively to 3-aminopyrrolidin-2-one, its 4-phenyl- and 5-methoxycarbonyl derivatives, predominantly to the trans isomer. Under the same conditions 1-amino-4-methoxycarbonylpyrrolidin-2-one was obtained from 3,4-di(methoxycarbonyl)-1H-pyrazoline, but 3,4,5-tri(methoxycarbonyl)-1H-pyrazoline did not react.

Effect of Carboxylic Acid Content on the Acute Toxicity of Oil Sands Naphthenic Acids

Fractions of methylated naphthenic acids (NAs) isolated from oil sands process-affected waterwere collected utilizing Kugelrohr distillation and analyzed by proton nuclear magnetic resonance (1H NMR) spectroscopy. 1H NMR analysis revealed that the ratio of methyl ester hydrogen atoms to remaining aliphatic hydrogen atoms increased from 0.130 to 0.214, from the lowest to the greatest molecular weight (MW) fractions, respectively, indicating that the carboxylic acid content increased with greater MW. Acute toxicity assays with exposure to monocarboxyl NA-like surrogates demonstrated that toxicity increased with increasing MW (D. magna LC50 values of 10 +/- 1.3 mM and 0.59 +/- 0.20 mM for the respective lowest and highest MW NA-like surrogates); however, with the addition of a second carboxylic acid moiety, the toxicity was significantly reduced (D. magna LC50 values of 10 +/- 1.3 mM and 27 +/- 2.2 mM forthe respective monocarboxyl and dicarboxyl NA-like surrogates of similar MW). Increased carboxylic acid content within NA structures of higher MW decreases hydrophobicity and, consequently, offers a plausible explanation as to why lower MW NAs in oil sands process-affected water are more toxic than the greater MW NAs.

Partial hydrogenation of methyl esters of sunflower oil catalyzed by highly active rhodium sulfonated triphenylphosphite complexes

Abstract The partial hydrogenation of polyunsaturated methyl esters of sunflower oil to monounsaturated methyl esters catalyzed by highly active rhodium sulfonated phosphite (Rh/STPP) complexes was studied in order to improve the quality of biodiesel in terms of increased oxidative stability and higher cetane numbers. The hydrogenation reaction proceeds under mild conditions and high catalytic activities (TOF = 38,000 h −1 ) were achieved employing Rh/STPP catalysts at a P/Rh molar ratio of 4 at 30–130 °C, 10–70 bar hydrogen partial pressure and molar ratios of C C/Rh between 700 and 6000 within 5–60 min of reaction time in conventional organic media.

Catalytic Processes for the Technical Use of Natural Fats and Oils

AbstractVegetable fats such as rapeseed oil, sunflower oil, palm oil or coconut oil consisting of triglycerides offer different carbon chain distributions. The use of these raw materials for the production of industrial chemicals as well as for fuel (biodiesel), which is finally a substitution for mineral oil, is a political discussion with various facets. The basic products such as fatty acids, fatty alcohols, and esters have different physical properties and lead to various areas of application depending on the carbon chain distribution. While the chain length range of C12 represents important raw materials for detergents, chain lengths of C18 are used mainly in industrial applications, e.g. as lubricants. Natural fatty alcohols are produced by the heterogeneous catalyzed high‐pressure hydrogenation of methyl esters or fatty acids. The unsaturated fats and oils can be derivatized catalytically by functionalization, oligomerization, oxidation or metathesis. Thereby, new functional groups are introduced into the oleochemical substrate. The carbon chain length can be increased or reduced respectively, or a branching in the fatty chain is introduced. Products with completely new properties and areas of applications are available due to these catalytic variations of fats and oils.

Catalyst in Basic Oleochemicals

Currently Indonesia is the world largest palm oil producer with production volume reaching 16 million tones per annum. The high crude oil and ethylene prices in the last 3 – 4 years contribute to the healthy demand growth for basic oleochemicals: fatty acids and fatty alcohols. Oleochemicals are starting to replace crude oil derived products in various applications. As widely practiced in petrochemical industry, catalyst plays a very important role in the production of basic oleochemicals. Catalytic reactions are abound in the production of oleochemicals: Nickel based catalysts are used in the hydrogenation of unsaturated fatty acids; sodium methylate catalyst in the transesterification of triglycerides; sulfonic based polystyrene resin catalyst in esterification of fatty acids; and copper chromite/copper zinc catalyst in the high pressure hydrogenation of methyl esters or fatty acids to produce fatty alcohols. To maintain long catalyst life, it is crucial to ensure the absence of catalyst poisons and inhibitors in the feed. The preparation methods of nickel and copper chromite catalysts are as follows: precipitation, filtration, drying, and calcinations. Sodium methylate is derived from direct reaction of sodium metal and methanol under inert gas. The sulfonic based polystyrene resin is derived from sulfonation of polystyrene crosslinked with di-vinyl-benzene. © 2007 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)