Mixture Of Fatty Acid Methyl Esters Research Articles

Fuel property evaluation of unique fatty acid methyl esters containing β-hydroxy esters from engineered microorganisms

Unique fatty acid methyl esters (FAME) containing β‑hydroxy esters were produced using an engineered microorganism by glucose fermentation. This study investigated the properties of the unique FAME mixture both neat and in blends with conventional diesel, as well as properties of β‑hydroxy esters. The unique FAME blend contained relatively shorter-chain FAME (average fatty acid chain carbon number 14.6) with 58 % monounsaturated fatty acids and 9 % saturated and monounsaturated β‑hydroxy acid chains. The unique FAME had significantly lower distillation T90 (321 °C versus 352 °C) and higher cetane number (56.7 versus 52) compared to soy biodiesel. Cloud points were within method repeatability. Unexpectedly (because of the lack of methylene-interrupted double bonds), the unique FAME had low oxidation stability (1.5 h) as determined by Rancimat induction period. Stability could be improved through addition of commonly used antioxidants. We speculate that monounsaturated β‑hydroxy FAME may be the source of this instability. Blends with conventional diesel up to 50 vol% showed similar kinematic viscosity (within method repeatability) as blends of conventional FAME. The unique FAME had no effect on distillation T90 even at the 80 % blend level. A 30 vol% blend into conventional diesel had a Rancimat induction period of only 2 h, very nearly the same as the neat unique FAME sample. The addition of antioxidants produced blends of acceptable stability. Based on an assessment of the properties of individual β‑hydroxy FAME molecules, they have higher boiling point, higher cloud point, lower cetane number, and potentially lower storage stability than analogous FAME not having the β‑hydroxy group. Removing them from the fuel product in the production process may result in a biodiesel product with superior properties to what is on the market today.

Revisiting the Potential of Group VI Inorganic Precatalysts for the Ethenolysis of Fatty Acids through a Mechanochemical Approach.

The utilization of biobased feedstocks to prepare useful compounds is a pivotal trend in current chemical research. Among a varied portfolio of naturally available starting materials, fatty acids are abundant, versatile substrates with multiple applications. In this context, the ethenolysis of unsaturated fatty acid esters such as methyl oleate is an atom-economical way to prepare functional C10 olefins with a biobased footprint. Despite the existence of a variety of metathesis catalysts for the latter process, there is a lack of readily available, efficient, and inexpensive catalytic systems based on earth-abundant metals (Mo, W) whose preparation does not require sophisticated syntheses and manipulations. Here, a systematic exploration of homogeneous and heterogeneous inorganic Mo, W (oxy)halides shows that MoOCl4, while inactive as a homogeneous species, forms active and selective silica-supported ethenolysis precatalysts able to reach equilibrium conversion of methyl oleate within a few minutes upon activation with SnMe4. Such heterogeneous MoOCl4-based precatalysts were easily accessed through mechanochemical solvent-free procedures and found to contain, upon characterization by elemental analysis and Raman spectroscopy, isolated (≡SiO)Mo(=O)Cl3 units or polymeric silica-supported [-O(≡SiO)nMoCl4-nO-]m (n = 1, 2) complexes depending on the molybdenum loading. The former isolated species exhibited a higher catalytic performance. The developed heterogeneous precatalysts could be applied to the ethenolysis of various substrates, including polyunsaturated fatty acid esters and industrial fatty acid methyl ester (FAME) mixtures from palm oil transesterification.

A comprehensive two-scale model for predicting the oxidizability of fatty acid methyl ester mixtures

The intricate mechanisms of oil thermooxidation and their accurate prediction have long been hampered by the combinatory nature of propagation and termination reactions involving randomly generated radicals. To unravel this complexity, we suggest a two-scale mechanistic description that connects the chemical functions (scale 1) with the molecular carriers of these functions (scale 2). Our method underscores the importance of accounting for cross-reactions between radicals in order to fully comprehend the reactivities in blends. We rigorously tested and validated the proposed two-scale scheme on binary and ternary mixtures of fatty acid methyl esters (FAMEs), yielding three key insights: (1) The abstraction of labile protons hinges on the carrier, defying the conventional focus on hydroperoxyl radical types. (2) Termination reactions between radicals adhere to the geometric mean law, exhibiting symmetric collision ratios. (3) The decomposition of hydroperoxides emerges as a monomolecular process above 80 °C, challenging the established combinatorial paradigm. Applicable across a wide temperature range (80 °C to 200 °C), our findings unlock the production of blends with controlled thermooxidation stability, optimizing the use of vegetable oils across applications: food science, biofuels, and lubricants.

Optimizing the subcritical water valorization of insect (Hermetia illucens l.) farming waste for biodiesel production

To counter the proliferation of secondary waste streams generated on insect (black soldier fly) farms, the present study integrated green water technology and acid-catalyzed transesterification as a basis to assess further value extraction potentials. By valorizing the waste streams, a process was developed to promote the circular economy paradigm. In this regard, wastes generated from a local insect farm were initially subjected to subcritical water extraction (SWE) for lipid recovery. The SWE process was optimized such that an enhanced lipid yield of 13.31 wt% was obtained at temperature, time, and solid loading conditions of 236.8 °C, 10 min of extraction, and 1 g/ 100 mL respectively. The lipids recovered were then subjected to an acid-catalyzed transesterification reaction for the production of a fatty acid methyl ester (FAME) mixture. A preliminary economic assessment of the process was also undertaken. The results showed that the wastes had the potential to be economically employed in the production of biodiesel that satisfied fuel property standards. In addition, the potential of employing the side streams as an animal feed was also highlighted due to the determined dominance of oligopeptides, which are known for their favorable bioactive properties. The results indicated that insect farming waste is a promising renewable source for high-quality biodiesel and animal feed production through the environmentally friendly biorefinery.

Biodiesel exhaust particle airway toxicity and the role of polycyclic aromatic hydrocarbons

Renewable alternatives to fossil diesel (FD) including fatty acid methyl ester (FAME) biodiesel have become more prevalent. However, toxicity of exhaust material from their combustion, relative to the fuels they are displacing has not been fully characterised. This study was carried out to examine particle toxicity within the lung epithelium and the role for polycyclic aromatic hydrocarbons (PAHs). Exhaust particles from a 20% (v/v) blend of FAME biodiesel had little impact on primary airway epithelial toxicity compared to FD derived particles but did result in an altered profile of PAHs, including an increase in particle bound carcinogenic B[a]P. Higher blends of biodiesel had significantly increased levels of more carcinogenic PAHs, which was associated with a higher level of stress response gene expression including CYP1A1, NQO1 and IL1B. Removal of semi-volatile material from particulates abolished effects on airway cells. Particle size difference and toxic metals were discounted as causative for biological effects. Finally, combustion of a single component fuel (Methyl decanoate) containing the methyl ester molecular structure found in FAME mixtures, also produced more carcinogenic PAHs at the higher fuel blend levels. These results indicate the use of FAME biodiesel at higher blends may be associated with an increased particle associated carcinogenic and toxicity risk.

RAPID METHOD FOR SIMULTANEOUS DETERMINATION OF CIS-9, TRANS-11 AND TRANS-10, CIS-12 CONJUGATED LINOLEIC ACID ISOMERS IN MILK BY GC-FID

Ruminant milk is the lead source of conjugated linoleic acid (CLA) in the human diet, with cis-9, trans-11 CLA being the major among all. Small amounts of trans-10, cis-12 CLA are also found in synthetic supplements. Since both isomers are biologically active with potential health benefits, there is great interest in quantifying them for quality control routines. An alternative method for the analysis of the aforementioned CLAs by fast gas chromatography (GC) is discussed in the present study. The fatty acid methyl ester mixture obtained by alkaline catalysis was injected into a GC equipped with a flame ionization detector (FID) and fitted with an ionic liquid SLB-IL111 chromatographic column (15 m × 0.10 mm × 0.08 µm). Separation was achieved in less than 5 min using a 168 °C isotherm run. Both CLA isomers were quantified by using of single point standard addition statistical approach. Results were contested to those obtained using the recommended 100 m long CP-Sil88 capillary column and none evidence of significant differences was found within 95% confidence interval. Therefore, the proposed method could be valuable to focused regulatory routines of large numbers of samples with greater analytical frequency.

Thermodynamically predicting liquid/solid phase change of long-chain fatty acid methyl esters (FAMEs) and its application in evaluating the low-temperature performance of biodiesel

BackgroundLong-chain FAMEs, also called biodiesel, are viewed as the alternative to petroleum diesel for renewability and sustainability. Because the fatty acid profiles significantly varied for the sources, the compositions significantly affected the biodiesel properties, such as cloud points. The cloud point of biodiesel indicates the phenomenon of solid-liquid phase change. Previous models for cloud point predictions were limited to known components in the mixtures. MethodsThe cloud points of the binary, ternary and multicomponent mixtures of fatty acid methyl esters were measured in this study. A cloud point prediction model was established based on phase equilibrium with the modified Universal functional activity coefficient (UNIFAC) model and excess fusion enthalpy for predicting the nonideal behaviors of the components resulting from the molecular shape and molecule interactions. Significant findingsThe developed thermodynamic model accurately predicts the cloud point according to compositions. The model extends the application scope to the low-temperature range. There had eutectic points in the phase diagrams when the mixtures consisted of either saturated FAMEs or unsaturated FAMEs. This study proved that saturated FAMEs regulate the cloud points, but unsaturated FAMEs affect them through group interactions. Moreover, the proposed model can predict unknown FAMEs mixture as it is built on the group contributions.

Partial Hydrogenation of Soybean and Waste Cooking Oil Biodiesel over Recyclable-Polymer-Supported Pd and Ni Nanoparticles

Biodiesel obtained through the transesterification in methanol of vegetable oils, such as soybean oil (SO) and waste cooking oil (WCO), cannot be used as a biofuel for automotive applications due to the presence of polyunsaturated fatty esters, which have a detrimental effect on oxidation stability (OS). A method of upgrading this material is the catalytic partial hydrogenation of the fatty acid methyl ester (FAME) mixture. The target molecule of the partial hydrogenation reaction is monounsaturated methyl oleate (C18:1), which represents a good compromise between OS and the cold filter plugging point (CFPP) value, which becomes too high if the biodiesel consists of unsaturated fatty esters only. In the present work, polymer-supported palladium (Pd-pol) and nickel (Ni-pol) nanoparticles were separately tested as catalysts for upgrading SO and WCO biodiesels under mild conditions (room temperature for Pd-pol and T = 100 °C for Ni-pol) using dihydrogen (p = 10 bar) as the reductant. Both catalysts were obtained through co-polymerization of the metal containing monomer M(AAEMA)2 (M = Pd, Ni; AEEMA− = deprotonated form of 2-(acetoacetoxy)ethyl methacrylate)) with co-monomers (ethyl methacrylate for Pd and N,N-dimethylacrilamide for Ni) and cross-linkers (ethylene glycol dimethacrylate for Pd and N,N’-methylene bis-acrylamide for Ni), followed by reduction. The Pd-pol system became very active in the hydrogenation of C=C double bonds, but poorly selective towards the desirable C18:1 product. The Ni-pol catalyst was less active than Pd-pol, but very selective towards the mono-unsaturated product. Recyclability tests demonstrated that the Ni-based system retained its activity and selectivity with both the SO and WCO substrates for at least five subsequent runs, thus representing an opportunity for waste biomass valorization.

Dehydration of fatty acid methyl ester mixtures from enzymatic biodiesel using a modified PVDF membrane

This study aimed to investigate the efficiency of microfiltration with a polymeric membrane in the dehydration of fatty acid ester mixtures. The dip-coating method was used to modify the surface of polyvinylidene fluoride (PVDF) hydrophilic membranes using silazane to render them hydrophobic. The membranes were characterized by the contact angle, Fourier-transform infrared spectroscopy (FTIR), zeta potential, field emission scanning electron microscopy (FESEM), membrane water absorption, silazane crosslinking to the membrane surface, and chemical compatibility of membranes to methanol. The microfiltration experiments were carried out in the dead-end and crossflow configurations. Membrane performance was evaluated by permeate flux values, mass reduction ratio, moisture, acidity, and glycerol content in the permeate. Mixtures with different compositions and concentrations of methyl ester, methanol, water, oleic acid, glycerol, and enzyme were used. Silazane deposition time of 60 min at 1 mg silazane/g toluene resulted in the best performance. The modification resulted in chemical and morphological changes in the membrane surface to render it hydrophobic changing its water contact angle from 0 to 94°. For dead-end and crossflow filtration configurations, the modified membranes presented the highest fluxes when compared to the unmodified control membrane, regardless of the composition of the mixtures. All biodiesel mixtures treated with the modified membrane had a decreased water content and an increased oleic acid content in the permeate. This work demonstrated that biocatalyzed fatty acid methyl esters (FAME) can be dehydrated using silazane-modified membranes, resulting in increased separation efficiency.

Potential of Raw Cattle Manure Bio-Oil as a Renewable Source of Antioxidants to Stabilize Fatty Acid Methyl Esters Mixtures

Potential of Raw Cattle Manure Bio-Oil as a Renewable Source of Antioxidants to Stabilize Fatty Acid Methyl Esters Mixtures

A magnetically separable acid-functionalized nanocatalyst for biodiesel production

A robust, magnetically recoverable Fe3O4@SiO2-SO3H core@shell nanoparticulate acid catalyst was successfully synthesized by a stepwise co-precipitation, coating, and functionalization. It was utilized as a heterogeneous catalyst for the transesterification and esterification of triglycerides and free fatty acids in Jatropha curcas oil (JCO) to a fatty acid methyl ester (FAME) mixture. This product conformed to ASTM standards for biodiesel. The as-prepared catalyst had a magnetic saturation of 30.94 emu g−1, surface area of 32.88 m2g−1, acidity of 0.76 mmol g−1, and pore diameter of 3.48 nm. The catalyst showed 98 ± 1% conversion using the optimized reaction conditions of methanol:oil molar ratio of 9:1, 8 wt% catalyst loading, 80 °C, and 3.5 h. The transesterification of JCO to FAME using the present catalyst benefitted from a very low activation energy of 37.0 kJ mol−1. The solid acid catalyst exhibited excellent chemical and thermal stability, and also reusability based on easy separation from the reaction mixture due to its inherently magnetic nature. Modest deterioration in oil conversion after multiple uses was offset by one-pot, quantitative regeneration of catalyst active sites. This enabled identical performance in JCO methyl transesterification and esterification in the 1st and 10th catalytic cycles.

Feasibility of additive winterization of biodiesel fuel derived from various eatable oils and fat

For simple removal of saturated fatty acid methyl esters (FAMEs) from a FAME mixture, our previous research described winterization using sorbitan palmitate without agitation. However, limited information exists on additive winterization of real oil biodiesels and their separation performance. We demonstrated the additive winterization of biodiesel fuel derived from commercial eatable oils and fat (palm, lard, cottonseed, rice, and soybean). Five biodiesel fuels were prepared through a transesterification reaction under alkali conditions. The biodiesel-additive mixtures were air-cooled over 48 h at a temperature equal to or several degrees lower than the cloud point (CP) of the biodiesel without agitation. The palm biodiesel showed a marked similarity to a simulated FAME mixture, and was separated into saturated FAME-rich solid fuel and unsaturated FAME-rich liquid fuel. The CP of the recovered liquid decreased by 6–10.5 °C, and the separation factors were between 2.4 and 7.7. The kinetic viscosity of the resultant liquid increased slightly because of the oleate fraction but was in the range of the biodiesel standard. These results indicate that additive winterization is useful for the separation and purification of biodiesel. Because the separation factor of the lard biodiesel winterization using sorbitan palmitate decreased (1.3–1.9), the separation improver retains scope for improvement under high stearate conditions. The relatively lower saturated FAME biodiesels (cottonseed, rice, and soybean) were predisposed to form a slurry during the winterization. However, the CP of the recovery liquid decreased 2–5 °C from the initial biodiesels. The separation factor and liquid recovery rate will increase with the use of a proper mechanical separation method such as filtration.

A β-cyclodextrin covalent organic framework used as a chiral stationary phase for chiral separation in gas chromatography

Chiral covalent organic frameworks (CCOFs) featuring chirality, stability, and good porosity have attracted a considerable amount of attention due to their important applications, such as asymmetric catalysis, chiral separation, and chiral recognition. In this study, a β-cyclodextrin (β-CD) covalent organic framework (β-CD-COF) diluted with polysiloxane OV-1701 was explored as a novel chiral stationary phase (CSP) for gas chromatography (GC) separation of racemates. The β-CD-COF coated capillary column had excellent selectivity, not only for the separation of linear alkanes, linear alcohols, fatty acid methyl esters mixture, the Grob mixture and positional isomers, but also for the resolution of chiral compounds, including chiral alcohols, aldehydes, ethers, and amino acid derivatives. In addition, the β-CD-COF-coated capillary column presented good repeatability and reproducibility. This work indicated the great potential of the CCOFs coated capillary column for the chromatographic separation of enantiomers.

Correlating the cloud point of biodiesel with its fatty acid methyl ester composition: Multiple regression analyses and the weighted saturation factor (wSF)

Biodiesel is an alternative fuel that is typically composed of fatty acid methyl esters (FAME) from transesterification of fats or plant oils with methanol. When blended with conventional diesel fuels, biodiesel improves combustion quality and reduces harmful exhaust emissions. On the other hand, biodiesel has poor cold flow properties that can compromise its use during cold weather in moderate temperature climates. In the present study, nine mathematical models were proposed to calculate the cloud point (CP) of biodiesel based on the concentrations and melting properties of the FAME components. Experimental data were compiled for four biodiesel fuels made from canola, palm and soybean oils and yellow grease (CaME, PME, SME and YGME) plus 24 binary admixtures of these fuels. Four models were inferred from multiple regression analysis of CP as functions of Xi = (MPixi; MPi = melting point and xi = mole fraction of the FAME species). These models yielded high correlation coefficients (R2 ≥ 0.997) and low absolute average deviations (AAD) ≤ 0.60 K from analysis of calculated (CPcalc) versus measured data. The results helped to identify species that influenced the CP of FAME mixtures. Five additional models based on the weighted saturation factor (wSF) index as an independent variable for correlating the CP of biodiesel were inferred. The indices were calculated as weighted sums of Xi terms for species present in the FAME mixtures. Both an arbitrarily assigned weight factor (wi) and the MPi of the pure FAME species were used to calculate the wSF indices. The wSF index-based models were developed from regression analysis of FA profile and experimental CP data for the 28 FAME mixtures. Four models yielded R2 = 0.968–0.977 and AAD ≤ 0.73 from analysis of CPcalcversus measured CP data.

Towards a universal ion source: Glow Flow mass spectrometry

A helium-microplasma ion source (Glow Flow) has been developed and characterised. It is engineered to be a simple design, of low-cost and can be readily retrofitted to most modern mass spectrometers. Initial assessment of its performance has shown it to be robust, reproducible and of high sensitivity. Glow Flow provides broad non-specific detection of samples from polar through to non-polar chemistries making it of wide utility. A study of persistent organic pollutants, polyaromatic hydrocarbons, low average-molecular-mass polymers (polyethyleneimine, polyethylene glycol, and polypropylene glycol) and a complex mixture of fatty-acid methyl esters by direct sample introduction using a nebulised heated nitrogen flow was conducted. The ability to make quantitative measurement was investigated using methyl stearate and a linear calibration plot gave a R2 = 0.999 and limit-of-detection of ∼100 fmol. This design is extremely stable, in operation. Typical ions commonly observed are intense protonated molecule ions, radical molecular ions, hydride abstracted ions, and oxygen adduct ions. At present this system is valuable to apply to small molecule analysis (m/z < 1000), and is easily interfaced to gas and liquid chromatography, and likely to be useful for imaging.

Effect of additive structure on the performance of biodiesel fuel winterization

The effects of additive structure on the separation of saturated fatty acid methyl esters (FAMEs) from FAME mixtures by winterization were investigated. Six sorbitan derivatives, seven palmitate derivatives, and sorbitan monopalmitate, which is known to improve the low-temperature separation of FAME mixtures, were studied. A model FAME mixture was prepared by blending saturated FAME (methyl palmitate) and unsaturated FAME (methyl oleate). Sorbitan derivatives that had fatty-acid groups with the same carbon chain length as the main saturated FAME in the FAME mixture improved the separation significantly. Shorter chain lengths and unsaturated fatty acid groups did not promote the winterization of FAME mixtures because their interactions with the main saturated FAME were too weak. Cyclic structures and hydroxy (OH) groups in the ester groups of the palmitate derivatives were found to be essential for preventing crystal growth and liquid contamination of the recovered solid phase. Cyclic structures affected the appearance of the FAME mixture during winterization, and the presence of OH groups affected the separation factor and the cloud point (CP) of the recovered liquid FAME. Span40, which has palmitate and sorbitan groups, was found to be the most effective additive for mixtures containing approximately 50 wt% methyl palmitate. The CP of the recovered liquid decreased 4–9 K, and the separation factors were between 3.6 and 7.5. These results will be useful for the separation and purification of saturated rich-FAME mixture such as palm, lard, mahua, neem, and jatropha biodiesels.

Simultaneous Determination of Free Fatty Acids and Esterified Fatty Acids in Rice Oil by Gas Chromatography

AbstractFree fatty acids (FFA) in crude rice oil were selectively and stoichiometrically derivatized to fatty acid N,N‐dimethylamides (FADMA) by catalytic condensation at 45 °C, and then esterified fatty acids (eFA) were directly converted to fatty acid methyl esters (FAME) at 37 °C. The mixture of FADMA and FAME formed in a single test tube was injected into the capillary column of a gas chromatograph (GC). No mutual contamination occurred between FFA and eFA, and reliability of the method was confirmed by comparison between GC data obtained by this method and by a conventional isolation method. The advantages of the present method are that no FFA isolation procedures are required, the reactions proceed under mild temperature conditions, and FFA and eFA can be analyzed simultaneously by GC.

A New Green Method for the Production Polyvinylchloride Plasticizers from Fatty Acid Methyl Esters of Vegetable Oils

AbstractThe current work has shown the potentials for the aerobic oxidation of fatty acid methyl ester (FAME) of vegetable oils in the production of polyvinylchloride (PVC) plasticizers with the exclusion of other reagents. The reaction mixtures contain epoxidized derivatives of FAME, and esters, with the quantity of the ester groups being higher than in the initial raw material. It was established that the increase in the additional ester groups resulting from the “aerobic” Baeyer‐Villiger (BV) reaction has a significantly positive influence on the plasticizing ability of the oxidized FAME mixtures for PVC when compared to the formation of epoxide compounds. The development of the technology for the production of PVC plasticizers proposed in this investigation provides an opportunity for resolving some of the environmental issues normally associated with the use of phthalate‐based plasticizers.

Optimum interaction of light intensity and CO2 concentration in bioremediating N-rich real wastewater via assimilation into attached microalgal biomass as the feedstock for biodiesel production

Impoverishing nutrients from wastewater via assimilation into microalgal biomass has gained footprint in bioremediation technologies. To ease the harvesting of mature microalgal biomass from effluent, this study proposed the employment of fluidized bed bioreactor to grow attached microalgal biomass onto polyurethane foam support material while bioremediating the N-rich real wastewater from chemical fertilizer manufacturing industry. The complete removals of all nitrogen species (NH4+-N, NO2−-N and NO3−-N) together with COD and total phosphorus were achieved at the optimum light intensity and CO2 concentration of 216μmol/m2 s and 9.1 %, respectively, giving rise to the attached microalgal biomass productivity of 0.094g/L/day. These performances were also found maintaining for at least 4 cycles of reiterative uses of spent polyurethane foam support material in similar fluidized bed bioreactor setup condition with every cycle being introduced with fresh N-rich real wastewater. The mechanism of attachment formations study predicted that the polysaccharides and proteins from microalgal extracellular polymeric substances had bridged the cells onto polyurethane foam support material during the initial colonization prior to populating and growing to cover the surfaces of support material. For biodiesel production, the extracted neutral lipid content of attached microalgal biomass was found to be four times higher than the suspended growth culture. From the transesterification process, about 97 %–98 % of attached microalgal lipid could be converted into fatty acid methyl esters (FAMEs) mixture. Interestingly, the degree of saturated fatty acids (SFA) in FAMEs was recorded increasing with the increase of cycles of reusing spent polyurethane foam support material. The presence of more SFA in FAMEs could overall enhance the oxidative stability and contribute to higher cetane number of produced biodiesel from facilely harvested attached microalgal biomass.

Understanding the thermal behaviour of blends of biodiesel and diesel: Phase behaviour of binary mixtures of alkanes and FAMEs

The study of the phase behaviour of binary mixtures of fatty acid methyl esters (FAME) and alkanes are here studied to understand the behaviour of the mineral diesel/biodiesel blends. Six binary mixtures of the most common saturated methyl esters (methyl stearate or methyl palmitate) with a saturated alkane (hexadecane, octadecane or eicosane) were evaluated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and optical microscopy. The binary mixtures studied show a more complex phase behaviour than previously reported, which it is shown to be dependent of the size difference between the alkyl chain length of the esters and the alkanes. It was found that in mixtures with equal alkyl chain length a co-crystal is formed, and when the alkane chain length is larger than in the FAME by two methylene groups the formation of a solid-solution increasing significantly the solid phase stability is observed. The results and conclusions derived from the phase behaviour of this set of binary mixtures, between alkanes and methyl esters, can be used as a model for the interpretation of the cloud and pour points increase in biodiesel blends (in special the ones with a rich fraction of methyl palmitate or methyl stearate when combined with mineral diesel with high content of octadecane or eicosane respectively).