Catalysts for Fatty Alcohol Production from Renewable Resources

Fatty alcohols may be produced through the processing of fatty acids or their esters derived from palm or coconut oils. Fatty alcohol technology can be classified into two categories (a) a slurry‐phase process in which the fatty acid or its ester is converted into alcohol using a powdered catalyst and (b) fixed bed technology in which the fatty acid or its ester is processed over a formed catalyst, e.g. tablets or extrudates. Historically copper‐based catalysts are employed for achieving ester hydrogenolysis. In recent years, studies were also focused on precious metal catalysts for this process. This paper will critically review existing literature pertaining to the catalysts that operate at diverse conditions, handle different feedstocks, and are compatible with a variety of unit operations used by the fatty alcohol manufacturers. There is an effort to develop environmentally friendly non‐chrome copper catalyst in this process. Some recent progress on bimetallic Cu‐Fe catalyst and understanding Cu‐Fe interaction has been reported. Current development on homogenous catalysts in this process was carefully reviewed. The catalyst deactivation mechanism has been investigated and effect of different impurities, mainly phosphorous, sulfur, chloride, water, glycerine and free fatty acid was thoroughly reviewed.     

Cleavage of Carboxylic Acid Moieties in Triacylglycerides During Non‐Catalytic Pyrolysis

Noncatalytic pyrolysis of triacylglyceride (TG) oils is an attractive option for production of renewable fuels and chemicals. This process produces 20–30 wt% of C₂–C₁₀ fatty acids due to the presence of carboxyl moieties in TG. To decipher this process’ mechanism, several compositionally distinct crop oil feedstocks with varied abundances of C₁₈ saturated and unsaturated TG carboxylic acid chains were pyrolyzed for short residence times in a laboratory‐scale continuous turbulent flow reactor. A comprehensive gas chromatographic analysis of the oxygenated products revealed the selective formation of linear saturated monocarboxylic acids (LSMCA) of less than C₁₁ in size, with a specific homological pattern featuring peaks for C₂–C₃, C₇ and C₉–C₁₀ LSMCA. The relative abundance of these size groups varied amongst the feedstocks cracked due to variations in the abundance of triunsaturated (linolenic), diunsaturated (linoleic) and monounsaturated (oleic) acids, respectively, in the original TG. We proposed a mechanism explaining the observed product speciation and homology profiles by the formation of acyloxyl biradicals as essential intermediates. High‐temperature C=C π‐bond hydrogenation with a concomitant σ‐bond cleavage yields C₉–C₁₀ LSMCA. This new path was confirmed by pyrolysis experiments with triolein in a GC pyroprobe.     

Formation and Microstructures of Whipped Oils Composed of Vegetable Oils and High-Melting Fat Crystals

This paper reports the experimental results of processes used for the formation of whipped oils composed of vegetable oils (salad oil) and high‐melting fat crystals [fully hydrogenated rapeseed oil rich in behenic acid (FHR‐B)]. No emulsifier was added to form this whipped oil. Microprobe FT‐IR spectroscopy, synchrotron radiation microbeam X‐ray diffraction (SR‐μ‐XRD), polarized optical microscopy, and differential scanning calorimetry (DSC) were employed to observe fine fat crystal particles of the most stable polymorph of β (β‐fat crystal), FHR‐B, and their adsorption at the air–oil surface before, during, and after the formation of the whipped oil. The results obtained revealed the following: (1) The preparation of an organogel composed of salad oil and small fibrous β‐fat crystals using a special tempering procedure was a prerequisite for forming whipped oil. (2) The β‐fat crystals were adsorbed at the air–oil surface to encapsulate the air bubbles during the formation process of whipped oil. (3) The values of overrun of the whipped oil reached >200 % after an aeration time of 30 min at 20 °C. (4) The SR‐μ‐XRD experiments demonstrated that the lamellar planes of the β‐fat crystals near the air–oil surface were arranged almost parallel to the air–oil surface plane. The present study provides the first evidence that tiny fat crystal particles may cause aeration in liquid oils without the addition of other whip‐assisting substances such as emulsifier crystals.     

Hydrodeoxygenation of waste fat for diesel production: Study on model feed with Pt/alumina catalyst

Hydrodeoxygenation of waste fats and oils is a viable method for producing renewable diesel oil. In this study a model feed consisting of oleic acid and tripalmitin in molar ratio 1:3 was hydrotreated at 325 °C with 20 bars H₂ in a stirred batch autoclave with a 5 wt% Pt/γ-Al₂O₃ catalyst, and samples were extracted periodically and analyzed on GC. Despite the significant hydrogen pressure hydrogenation of both reactants were limited and decarboxylation or decarbonylation of the ester and carboxylic acid functionalities were highly favored, yielding carbon chain lengths of odd numbers. Moreover, Pd/γ-Al₂O₃ was observed to be slightly more active than Pt/γ-Al₂O₃ and had a higher ratio of decarboxylation and decarbonylation to hydrogenation, while Ni/γ-Al₂O₃ was substantially less active than Pt and also showed a markedly lower ratio of decarboxylation and decarbonylation to hydrogenation. Variation of the temperature showed that triglycerides as well as free fatty acids were converted at all investigated temperatures, but the conversion of oleic acid increased from 6% to 100% when the temperature was increased from 250 °C to 325 °C. The tripalmitin reacted via a palmitic acid intermediate, and its conversion was limited by formation of this free fatty acid.     

2-Monochloro-1,3-propanediol (2-MCPD) Dynamics in DGF Standard Methods and Quantification of 2-MCPD

Pure 2-monochloro-1,3-propanediol (2-MCPD) was successfully synthesized, identified, and first quantified by the Deutsche Gesellschaft für Fettwissenschaft (DGF) standard method C-VI 18 (10), with a calculable detection sensitivity relative to 3-monochloro-1,2-propanediol (3-MCPD) of 3.26-fold, using a QP-2010 GC/MS instrument. The detection sensitivities of other GC/MS instruments can be determined using the individual ion-ratio of the fragment to the precursor of 3-MCPD-d ₅ as a reference. Quantification of 2-MCPD is possible using conventional 3-MCPD-d ₅ esters as internal-standards, without a calibration curve of pure 2-MCPD. The dynamics of 2-MCPD during DGF standard methods C-VI 18 (10) were directly analyzed using NMR and indirectly using GC/MS. 2-MCPD was partly converted to glycidol under basic conditions of the transesterification step, and the glycidol was reconverted to 2-MCPD under acidic conditions of the extraction step. 2-MCPD spiked in soybean oil was detected as 98 mol% 2-MCPD and 2 mol% 3-MCPD from the area ratio in GC/MS. In contrast, glycidyl stearate spiked in soybean oil was detected as 5.5–5.7 mol% 2-MCPD and 94.3–94.5 mol% 3-MCPD from the corrected area ratio in GC/MS.     

Feruloylated Products from Coconut Oil and Shea Butter

The synthesis of feruloylated coconut oil and feruloylated shea butter were demonstrated in 0.5-L scale, shaken, batch reactions. Ethyl ferulate and the vegetable oil/fat were combined in a 1.0:1.3 mol ratio in the presence of Candida antartica lipase B immobilized on an acrylic resin (Novozym 435) at 60 °C. The transesterification of ethyl ferulate with coconut oil and shea butter reached equilibrium conversions, after 22 days, of 63 and 70%, respectively, with the shea butter transesterifications producing a white precipitate not observed in the coconut oil transesterifications. The faster transesterification rates, equilibrium conversions and white precipitate were shown to result from di- and monoacylglycerols (DAG and MAG) present in the shea butter. The transesterification of ethyl ferulate and coconut oil was also tested in a continuous, enzymatic, packed-bed bioreactor using Novozym 435 at 60 °C to produce feruloylated coconut oil at rates of 0.5–0.9 kg/day over 4.5 months. The feruloylated coconut oil acylglycerol species were identified by LC–MS analysis of transesterification reactions of ethyl ferulate with medium chain triacylglycerol (TAG) standards, C8–C14. The feruloylated vegetable oils possessed an ultra violet (UV) absorbing λ _max 328 nm, making them good UVAII absorbers, as defined by the U.S. Food and Drug Administration. The feruloylated coconut oil possessed a 17.5% higher absorption capacity than feruloylated shea butter on a per weight basis. All the feruloylated vegetable oils possessed rapid antioxidant capacity (50% reduction of initial radical concentration <5 min) at the concentrations tested, 0.5–2.5 mM. Feruloylated coconut oil possessed chemical and physical characteristics that suggested it would be fungible for feruloylated soybean oil in current retail formulations.     

Antioxidant Activity of Osage Orange Extract in Soybean Oil and Fish Oil during Storage

The food industry is seeking natural antioxidants for edible oils that have comparable activity to synthetic counterparts. In this study, Osage orange extract (OOE) rich in osajin (42.9%) and pomiferin (30.0%) was obtained after hexane extraction of the fruit, and its antioxidant activity was examined in stripped soybean oil (SBO) and fish oil (FO), in which antioxidants and polar compounds were removed. The antioxidant activity of OOE was compared with commercial natural antioxidants (i.e., rosemary extract and mixed tocopherols) and a synthetic antioxidant, butylated hydroxytoluene (BHT), during storage at 25 and 40 °C. The 0.1% OOE had stronger antioxidant activity than 0.1% rosemary extract and 0.1% mixed tocopherols in both oils at 25 and 40 °C. Its activity was similar to 0.02% BHT in SBO and was similar or slightly stronger than 0.02% BHT in FO. When OOE was studied at 0.05, 0.1, and 0.2%, there was a weak dose–response in SBO but a stronger dose–response in FO. Headspace volatile analysis using solid phase micro-extraction (SPME) combined with GC–MS indicated that 0.1% OOE was very effective in preventing the formation of volatile oxidation products in both oils. Although it should be further tested for safety before the actual use, this study shows that OOE can be developed as an antioxidant for edible oils.     

Synthesis and Characterization of Potential Bio-Based Lubricant Basestocks via Epoxidation Process

Chemical modifications of vegetable oils may be applied for the purpose of improving their physicochemical properties in their usage for the bio-based lubricants. The vegetable oils with a high percentage of oleic acid, such as soybeans and rapeseed oils, are important raw materials to obtain the biolubricants. In this particular study, the oleic acid was esterified with 1-octanol, followed by epoxidation. The oxirane ring opening reaction was performed using different alcohol structures (linear, branched, and cyclic), in order to evaluate their influence on the final physicochemical properties with the synthesized samples. These aforesaid reaction steps were followed by ¹H nuclear magnetic resonance and the main physicochemical properties in the intermediate and final samples were assessed. The highest oxidative stability was observed for the samples obtained, using a cyclic alcohol at the oxirane ring opening reaction (230 min), followed by the linear alcohols with the branched alcohol presenting the lowest oxidative stability (124 min). The pour point values for the samples synthesized with the branched alcohol were slightly better than those with the linear and cyclic alcohols. All the synthesized samples showed high viscosity indexes (>130) and kinematic viscosities at 40 °C, ranging from 30 to 33 cSt (application degree ISO VG-32), which are adequate for their use in the formulation of bio-based lubricants.     

Investigation of Oil and Protein Contents of Eight Sudanese Lagenaria siceraria Varieties

The composition of the oil and protein contents of eight Lagenaria siceraria varieties was characterized in order to evaluate their suitability as a source of edible oil and protein. The physicochemical properties and fatty acids of seed oils were determined. The oil yield ranged from 24.11 to 26.32 %. The refractive indices and relative densities of the oils fell within the narrow ranges of 1.464–1.468 and 0.857–0.907 g/cm³, respectively. The saponification value ranged from 158.48 to 179.52 mg KOH/g, unsaponifiable matter was between 0.749 and 0.937 %, and the peroxide values were lower than Codex values for vegetable oils. The principal fatty acids were linoleic (62.1–67.9 %), oleic (11.54–15.46 %), palmitic (12.13–14.03 %), and stearic (6.71–7.71 %) acids. Low linolenic acid levels were also observed (<1 %) within the range of 0.32–0.44 %. The major essential amino acids were arginine (2.04–3.77 g/100 g), leucine (1.245–1.726 g/100 g), phenylalanine (0.803–1.396 g/100 g), and lysine (0.921–1.383 g/100 g). The non‐essential amino acids were glutamic acid (2.5–4.37 g/100 g), aspartic acid (1.39–2.36 g/100 g), serine (0.69–1.19 g/100 g), glycine (0.79–1.37 g/100 g), alanine (0.72–1.37 g/100 g), and proline (0.63–1.02 g/100 g). Nine minerals (Na, Ca, Mg, K, Cu, Fe, Mn, Zn, and P) were determined with significant (p < 0.05) differences. The studied oils showed promising results and can be used in the food, cosmetics, and pharmaceutical industries. This is the first study on the eight L. siceraria seed varieties grown in Sudan, opening the way for further studies on these seeds.     

Rapid FT-NIR Analysis of Edible Oils for Total SFA, MUFA, PUFA, and Trans FA with Comparison to GC

Declarations of the total content of trans fatty acids (FA) and saturated FA (SFA) are mandatory on food labels in the US and Canada. Gas chromatography (GC) has been the method of choice for the determination of FA composition. However, GC is time consuming and requires conversion of fats and oils to their FA methyl esters. In the present study, a recently published Fourier transform near-infrared (FT-NIR) spectroscopic procedure was applied to the rapid (<5 min) determination of total SFA, monounsaturated FA (MUFA), polyunsaturated FA (PUFA), and trans FA contents of 30 commercially available edible fats and oils. Good agreement was obtained between the GC and FT-NIR methods for the determination of total SFA, MUFA, and PUFA contents. Differences between the two methods were apparent for the determination of trans fat at trans fat levels <2 % of total fat. The analytical determinations of total SFA, MUFA, and PUFA contents for many of the oils examined differed from the respective values declared on the product labels. Our findings demonstrate that the FT-NIR procedure serves as a suitable alternative method for the rapid determination of total SFA, MUFA, PUFA and trans FA contents of neat vegetable oils.     

Crystallization Behavior of Molecular Compound in Binary Mixture System of 1,3‐Dioleoyl‐2‐Palmitoyl‐sn‐Glycerol and 1,3‐Dipalmitoyl‐2‐Oleoyl‐sn‐Glycerol

Previous studies showed that the stable β‐form of molecular compound (MC) crystals having a double‐chain‐length structure is formed in a binary mixture system of 1,3‐dioleoyl‐2‐palmitoyl‐sn‐glycerol (OPO) and 1,3‐dipalmitoyl‐2‐oleoyl‐sn‐glycerol (POP) with a 1:1 concentration ratio of OPO and POP. The use of MC crystals made of POP and OPO for edible applications, such as margarine, is advantageous due to no‐trans, low‐saturated, and high‐oleic fats. Industrial manufacturing technology involves rapid cooling processes, and the kinetic properties of crystallization of MC of OPO and POP are required. In this study, we clarified the crystallization of MC of OPO and POP under rapid cooling at rates of 1–150 °C min^?1, using synchrotron radiation time‐resolved X‐ray diffraction and differential scanning calorimetry methods. The main results are as follows: (1) POP and OPO crystallized in separate manners without the formation of MC crystals under rapid cooling (>40 °C min^?1), while MC crystals started to form with decreasing rates of cooling in addition to the POP and OPO crystals (<30 °C min^?1); (2) metastable and stable forms sub‐α, α, β′, and β of POP and OPO were formed, whereas the MC crystals of β were formed during the cooling processes; and (3) the heating processes after crystallization by rapid cooling caused separate melting of the metastable and stable forms of POP and OPO crystals and the formation of MC crystals of β made of POP and OPO, as well as melting of the MC crystals alone.     

Moisture Removal Substantially Improves the Efficiency of in Situ Biodiesel Production from Soybeans

In an effort to reduce the production cost of biodiesel, we previously described an approach termed “in situ transesterification” wherein the transesterification of a vegetable oil occurred directly in its raw agricultural material. In that method, substantial quantities of reagents were required to achieve high-efficiency transesterification. Here we report that by drying the substrate a marked reduction in the reagent requirements was achieved. Reaction conditions for maximum fatty acid methyl ester (FAME) production were identified using statistical experimental design methods. In 16-h reactions with 5 g of flakes (2.6% moisture) and 18 mL of 0.10 N NaOH in methanol, 97% theoretical maximum transesterification was achieved. For dry flakes, optimal transesterification was achieved in 10 h in reactions containing 5 g of flakes and 12 mL of 0.10 N NaOH in methanol. This represented a 60% reduction in methanol and a 56% reduction in NaOH use compared with the transesterification of full-moisture flakes. Under these conditions the degree of transesterification was 100% of the theoretical maximum. The transesterification of 20 kg of flakes with a moisture content of 0.8% was conducted under optimal reaction conditions. Both triacylglycerols (TAG) and phosphoacylglycerols (PL) were transesterified to high degrees, with an overall efficiency of 97.3% of the maximum theoretical efficiency. PL were not detected in the flakes following transesterification, and the amount of remaining unreacted TAG was only 1.0% of that input. Following washes with water, 0.5 M NaCl, and dilute NaOH, the recovered FAME met the ASTM specifications for biodiesel. The tocopherol levels of the FAME exceeded by 76% those of a representative commercial biodiesel. Soy flakes retained 97% of their protein following in situ transesterification. Mention of brand or firm names does not constitute an endorsement by the US Department of Agriculture over others of a similar nature not mentioned.     

High-yield enzymatic glycerolysis of fats and oils

Several triglyceride fats and oils were reacted with glycerol using lipase as catalyst. A batch system with magnetic stirring was used without the addition of any solvents or emulsifiers. In all cases a mixture of mono-, di- and triglycerides was obtained. However, the yield of monglyceride (MG) depended strongly on the reaction temperature: at higher temperatures approximately 30% MG was produced at equilibrium while at lower temperatures a yield of 65%–90% MG was obtained for most of the fats examined. The upper temperature limit below which a high MG yield could be attained was designated the critical temperature (T_c). The value of T_c depended on the fat type and was found to vary between 30°C and 46°C for naturally occurring hard fats. A high MG yield could not be obtained for fully hydrogenated tallow and lard under the conditions described here. Of the three liquid oils examined, rapeseed oil and olive oil had a T_c of 5°C and 10°C respectively whereas a high yield of MG could not be obtained with corn oil at 5°C or greater. The maximum yield of MG below T_c also depended on the fat type: the highest yields being obtained for olive oil (90%), palm stearin and milk fat (80%) and the lowest yield for palm oil (67%). In all cases a high yield of MG was accompanied by solidification of the reaction mixture. The effect of enzyme type on MG production was examined for palm oil and palm stearin and the effect of water concentration was examined for palm oil.     

Catalyst characteristics and performance in edible oil hydrogenation

Hydrogenation of vegetable oils was first discovered in the beginning of this century and quickly became a major processing step in the fats and oils industry. Hydrogenation changes a liquid oil made of triglycerides of polyunsaturated fatty acids to one containing mostly monounsaturated fatty acids. This procedure improves the functionality and flavor stability of the oil. The process is a complex series of reactions occurring in a three-phase slurry reactor in a batch mode primarily utilizing supported Ni catalysts and can result in a variety of products. A good catalyst for edible oil hydrogenation must have good activity, selectivity, poison resistance and filterability. The physical characteristics of the catalyst affect these attributes greatly. This paper discusses these attributes and how a catalyst and the operating conditions affect them.     

Selective distribution of saturated fatty acids into the monoglyceride fraction during enzymatic glycerolysis

Four triglyceride fats and oils (beef tallow, lard, rapeseed oil and soybean oil) were reacted with glycerol while using lipase as the catalyst. For all fats examined, at reaction temperatures above the critical temperature (T_c), the fatty acid compositions of the monoglyceride (MG) and diglyceride (DG) fractions and of the original fat were similar. A relatively low yield of MG was obtained (20–30 wt%). When the reaction was carried out with beef tallow or lard at a temperature below the T_c (40°C), the concentration of saturated fatty acids in the MG fraction was 2 to 4 times greater than that in the DG fraction. Correspondingly, the concentration of unsaturated fatty acids in the DG fraction was more than two times greater than that in the MG fraction. At 5°C, a similar trend was observed for rapeseed oil and soybean oil. Direct analysis of partial glycerides during glycerolysis by high-temperature gas-liquid chromatography showed that below T_c the content of C16 MG increased relatively more than C18 MG. C36 DG and C54 TG were apparently resistant to glycerolysis. Preferential distribution of saturated fatty acids into the MG fraction was accompanied by a high yield of monoglyceride (45–70 wt%) and solidification of the reaction mixture. It is concluded that during glycerolysis below T_c, preferential crystallization occurs for MGs that contain a saturated fatty acid.     

Structures and Polymorphic Transitions of Triacylglycerols, SOS and POS Thin Films: A Study on Temperature Dependence

X-ray reflectivity (XR) and scanning probe microscopy (SPM) were used to examine the structures, polymorphic transitions, and surface morphologies of triacylglycerol (TAG), 1,3-stearin-2-olein (SOS) and 1-palmitin-2-olein-3-stearin (POS) thin films supported on Si substrates. The structural parameters: thickness, electron density, and surface/interface roughnesses of TAG thin films were determined by the nonlinear least-squares regression of XR profiles to reveal their temperature dependences. In the lower temperature regimes, we observed Bragg peaks without significant interference fringe patterns in the XR profiles. SPM at room temperature displayed isolated islands on TAG thin films with surface undulations. Whereas in the higher temperature regimes in which the Bragg peaks disappeared, the interference fringe patterns became prominent. The analyses of the XR profiles indicated the structural change in thin films from three layers to single layer on Si substrates with increasing temperature. However, the temperatures at which the structural change occurred were obviously different between SOS and POS thin films.     

A Sustainable Process for the Production of Varnishes Based on Pelargonic Acid Esters

This work demonstrates the possibility of using pelargonic acid (PA) esters as solvents for vegetable-based varnishes. First, PA was efficiently produced through a chemocatalytic cleavage of oleic acid, practicing an optimized scale-up of previously developed conditions. PA was then esterified with several alcohols ROH (R = Me, i-Pr, n-Bu, n-Hex, 2-ethylhexyl, and sec-octyl) and the products were formulated with a commercial rosin (Phenolic Modified Rosin Esters). Dynamic light scattering (DLS) measures and determination of rheological parameters of the corresponding varnishes disclosed their suitability for applications in offset, coldset, heatset printing inks, and coatings. Furthermore, inks obtained were used to efficiently produce preliminary industrial offset prints.     

Retardation of Crystallization of Diacylglycerol Oils Using Polyglycerol Fatty Acid Esters

Liquid oil containing high concentrations of diacylglycerols (DAG > 80 %, hereafter referred to as DAG-rich oil) is generally more likely to cause precipitation at chilled temperatures (clouding phenomena) than triacylglycerol-based oil. The clouding phenomena that occur during long-term storage of DAG-rich oil are unwanted in consumer products and therefore, must be prevented. In the present study, we attempted to retard precipitation by adding food emulsifiers, polyglycerol fatty acid esters (PGFE) containing different fatty acid moieties. DSC, polarized optical microscopy, and X-ray diffraction studies revealed that the addition of 0.2 % PGFE containing palmitic and oleic acid moieties very effectively retarded precipitation in the DAG-rich oil. To confirm these observations, we prepared a model DAG oil to mimic DAG-rich oil and examined the retardation behavior of high-melting DAG fractions using PGFE. The results are discussed in terms of the effects of PGFE additives on the pre-nucleation processes of high-melting fractions in DAG-rich oil.