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The efficient conversion of low-grade acidic oils to biodiesel is still a great challenge due primarily to the presented free fatty acids (FFAs) and moisture that significantly activate the used catalysts. In this premise, the acidic aluminosilicates (AAS) were employed as catalyst supports for loading of molybdenum and zirconium metals to synthesize the solid acid catalysts of molybdenum and zirconium doped aluminosilicates (ZrMo-AAS). The so-synthesized composite catalysts were characterized by various physicochemical techniques, and their catalytic activities were evaluated for the efficient biodiesel production by using acidic soybean oils as feedstocks. Results revealed that the targeted solid catalysts featured dual Bronsted-Lewis acidic sites and mesoporous structure with the acidity of 719 μmol/g and surface area of 459.7 m2/g, displaying high catalytic performances for the concurrent transesterification of triglycerides and esterification of FFAs with 92.3% of oil conversion and full FFA conversion to biodiesel at a reaction temperature of 130 °C for 12 h with a methanol/oil molar ratio of 30. This solid catalyst had good water and FFA-resistance capacity even with water content to 1% and FFA content of 40%, and moreover could be easily recovered by filtration with a steady reusability with a slight attenuation in the activity after five time reuses, rendering it to have the potential of cost-effective production of biodiesel from the low-grade oils. [ABSTRACT FROM AUTHOR]

• MoAl@H-SiO 2 catalyst with hierarchical porous structure was prepared. • The hierarchical structure could obviously enhance the catalytic performance. • This catalyst was effective for one-pot biodiesel production from low-value oils. • This catalyst has good recyclability and high resistance to acid and water. The current research investigated the feasibility of using hierarchical porous solid catalysts for ameliorating the mass transfer of larger oil molecules to efficiently catalyze the oil transesterification particularly with low-value acidic oils as feedstocks, in response to the demand for the durable and green production of biodiesel. For this purpose, a series of ordered macro-mesoporous hierarchical MoAl@H-SiO 2 catalyst was synthesized in acidic solution by in-situ synthesis method using polymethyl methacrylate (PMMA) and Pluronic P123 as double templates. The structural and morphological features as well as the acidic properties were validated by several catalyst characterization techniques. It was shown that Mo and Al metals were uniformly dispersed on the H-SiO 2 support, and the ordered macro–mesoporous hierarchical structure was remained hardly unchangeable even after these metals had been loaded. The so-prepared solid catalyst demonstrated both Lewis and Bronsted acid sites, thus displaying high catalytic activities for concurrently converting of triglycerides and free long-chain fatty acids (FFAs) to biodiesel. Such technical advantages could impart a one-pot process for the cost-effective biodiesel production from low-value acidic oils, without requirement for the pretreatment of removing these FFAs. By comparing with the similar catalysts without hierarchical porous structure or with single metal oxide, the macro-mesoporous hierarchical structure could obviously enhance the catalytic performance due to the intensification of mass transfer and diffusion, meanwhile the synergism between the double Al and Mo species was also shown for the fabricated solid catalyst to promote the oil transesterification. Further, this hierarchical porous MoAl@H-SiO 2 catalyst owned high FFA- and water resistance capacity, and still had considerable activity after repeated use for five times, endowing its great potential to be used for the production of biodiesel especially from low-value oil feedstocks. [ABSTRACT FROM AUTHOR]

Improving the reactant mass transfer on the catalyst surface is a feasible approach to fabricate a robust solid catalyst for efficiently promoting the biomass macromolecules-involving reactions, specifically for biodiesel production by using non-edible acidic oils as feedstocks. In this premise, to reduce the mass transfer resistance, the hierarchical porous SOM-ZIF-8 was firstly synthesized using polystyrene spheres (PS) as templates and then employed as catalyst supports for loading of Keplerate-type polyoxomolybdates {Mo 132 } to prepare a novel {Mo 132 }@SOM-ZIF-8 solid acid catalyst. The catalyst characterization results revealed that the active species of {Mo 132 } clusters were well-dispersed on the SOM-ZIF-8 support and the primary framework of the SOM-ZIF-8 support remained nearly unaltered after the preparation processes. This prepared catalyst featured three-dimensional ordered hierarchical porous structure and dual Bronsted-Lewis acid sites, with a large surface area of 736.26 m2/g and high acidity of 903 μmol/g, presenting high activities for concurrent triglyceride transesterification and free fatty acids (FFAs) esterification. With the acidic soybean oils as feedstocks, 93.9 % of oil conversion and full FFA conversion to biodiesel were achieved over this solid catalyst at 130 °C for 8 h with a catalyst loading of 2 wt%, thus imparting the great potential for a one-pot efficient biodiesel manufacture from the acidic oils to comply with the demand of green and clean production. The synergy between the hierarchical porous structure and the strong acidity emerged, thus boosting the catalytic performance of this solid catalyst for the heterogeneous biodiesel production. The good FFA and moisture-resistance capacity was shown for this catalyst even in the case of moisture content of 3 % and FFA content of 25 %. Further, this catalyst showed excellent reusability without significantly losing its catalytic performance even after five runs, providing a deeper insight into constructing efficient solid catalysts with hierarchical porous structure that are utilized for cost-effective production of biodiesel from the non-edible acidic oils. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The Mo/Ce/H-TiO 2 catalyst with hierarchical porous structure was prepared. • The hierarchical porous structure can improve the mass transfer of oil molecules. • Oil transesterification and FFA esterification can be achieved concurrently. • This catalyst has good recyclability and high resistance to acid and water. Strengthening the reactant transfer on the catalyst surface is a feasible tactic to develop an efficient solid catalyst in particular for the large biomass molecule-involving reaction. In the current research, hierarchical porous Mo/Ce/H-TiO 2 catalysts were prepared by evaporation-induced self-assembly method using polymethylmethacrylate colloidal crystals and Pluronic F127 as templates, and then applied for simultaneously catalyzing transesterification-esterifiications of low-value acidic oils for cost-effective biodiesel production. The presented three-dimensional hierarchical meso/macroporous in this solid catalyst could efficiently boost the mass diffusive rate of oil macromolecules and also provide more easily approaching active sites, thus improving its catalytic activity in comparison with the control catalysts with no hierarchical porous structure. The dual Mo/Ce oxides with Brønsted-Lewis acidic sites were finely embedded over the hierarchical meso/macroporous TiO 2 support and were acted as active centers of the Mo/Ce/H-TiO 2 catalyst, wherein the synergism of Brønsted and Lewis acid sites had a significant influence on its inherent catalytic activity. This catalyst displayed excellent catalytic performance for both the transesterification of triglyceride and esterification of free fatty acids (FFAs). By using this catalyst, the oil conversion of 93.8 % were achieved at 140 °C for 8 h with the methanol-to-oil molar ratio of 30:1 and catalyst loading of 5 wt%. Moreover, the activation energy Ea and Arrhenius constant A for the oil transesterification were calculated to be 51.0 kJ/mol and 10.7 × 103 min−1, respectively. Furthermore, the good FFAs and water tolerant capacity was shown for this catalyst and it still remained high activities after reuse for five cycles, rendering it to be potential of efficient and sustainable biodiesel manufacture from the FFAs-containing acidic oils. [ABSTRACT FROM AUTHOR]

Hierarchical porous materials have gained much attention as promising heterogeneous catalyst supports due to their high efficiency of mass transfer and high exposure of active centers. In this research, the hierarchical porous SAPO-34 support with microporous, mesoporous, and macroporous hierarchical structure was initially prepared by in-situ alkali etching. Then, Mo and W oxides were incorporated into this hierarchical porous support by using the impregnation method to prepare Mo 15 W 15 /HSAPO-34/70 catalyst. This developed catalyst was applied to concurrently catalyze the oil transesterification and free fatty acid (FFA) esterification to biodiesel as the low-value oils severed as feedstocks. The textural and physicochemical properties of the nanocatalysts were evaluated by XRD, XPS, SEM, EDS, TEM, UV–vis, NH 3 -TPD, Py-FTIR, and nitrogen porosimetry measurement. This catalyst had hierarchical porous structure to ameliorate the large oil molecular transfer, and featured dual Brønsted-Lewis acid sites to synergistically boost the catalytic efficiency for the biodiesel production. Over this catalyst, the oil conversion of 90.1 % and full FFA conversion were achieved under optimized operation conditions, therefore imparting to one-pot conversion to biodiesel with low-value oils as feedstocks. In addition, this catalyst not only exhibited superior tolerance to moisture and FFAs, but also retained high activities after five reuse cycles, thus revealing its tremendous potential of being used in durable and efficient biodiesel production. The present work opens a new avenue for synthesizing a robust solid acid catalyst to achieve a one-pot biodiesel production from low-value oils. [Display omitted] [ABSTRACT FROM AUTHOR]

Hierarchical porous materials have gained much attention as promising heterogeneous catalyst supports due to their high efficiency of mass transfer and high exposure of active centers. In this research, the hierarchical porous SAPO-34 support with microporous, mesoporous, and macroporous hierarchical structure was initially prepared by in-situ alkali etching. Then, Mo and W oxides were incorporated into this hierarchical porous support by using the impregnation method to prepare Mo 15 W 15 /HSAPO-34/70 catalyst. This developed catalyst was applied to concurrently catalyze the oil transesterification and free fatty acid (FFA) esterification to biodiesel as the low-value oils severed as feedstocks. The textural and physicochemical properties of the nanocatalysts were evaluated by XRD, XPS, SEM, EDS, TEM, UV–vis, NH 3 -TPD, Py-FTIR, and nitrogen porosimetry measurement. This catalyst had hierarchical porous structure to ameliorate the large oil molecular transfer, and featured dual Brønsted-Lewis acid sites to synergistically boost the catalytic efficiency for the biodiesel production. Over this catalyst, the oil conversion of 90.1 % and full FFA conversion were achieved under optimized operation conditions, therefore imparting to one-pot conversion to biodiesel with low-value oils as feedstocks. In addition, this catalyst not only exhibited superior tolerance to moisture and FFAs, but also retained high activities after five reuse cycles, thus revealing its tremendous potential of being used in durable and efficient biodiesel production. The present work opens a new avenue for synthesizing a robust solid acid catalyst to achieve a one-pot biodiesel production from low-value oils. [Display omitted] [ABSTRACT FROM AUTHOR]

The exploration of efficient and recyclable catalysts is highly desirable for catalytic biodiesel manufacture from low-grade acidic oils, in response to the demand of clean production and environmental concerns. For this aim, phosphotungstic acid (HPW) was firstly modified by tin metal, and then embedded on ZIF-8 metal-organic formworks (MOFs) to synthesize the SnPW@ZIF-8 catalyst. Catalyst characterization results revealed that the active species of Sn-doped HPW with Keggin-type anion structure were well-dispersed on the ZIF-8 support, and this catalyst featured high surface area with dual Brönsted-Lewis acid sites, posing enhanced catalytic performances to the oil transesterification and esterification of free fatty acids (FFAs) presented in oils. By applying this catalyst, 92.8 % of oil conversion and 97.4 % of FFAs conversion were concurrently achieved under the optimized conditions, rendering one-pot conversion of low-grade acidic oils to biodiesel and minimizing the complex and tedious separation processes. Moreover, the higher water and FFA-resistance capacity was shown for this catalyst, imparting its more suitable for the efficient biodiesel production particularly with the acidic oils as feedstocks. Further, this catalyst could still remained high catalytic efficiency after five cycle reuses due to the strong interactions of the SnPW with the imidazole groups in the ZIF-8, making it to have the potential of cost-effective and efficient production of biodiesel from the low-grade acidic oils. [Display omitted] • SnPW@ZIF-8 solid catalyst with duai Brönsted-Lewis acid site were prepared. • This catalyst was effective for one-pot biodiesel production from low-grade oils. • Oil transesterification and FFA esterification can be achieved simultaneously. • This catalyst has good recyclability and high resistance to acid and moisture. [ABSTRACT FROM AUTHOR]

This present research aims at developing an efficient and reusable base catalyst to improve the biodiesel production for the need of green chemistry and sustainable development. To achieve this, the copolymer, namely poly(allylglycidyl ether-divinylbenzene-glycidyl methacrylate) (poly(AGE-DVB-GMA)), was firstly incorporated in the Fe 3 O 4 nanoparticles forming magnetic Fe 3 O 4 -poly(AGE-DVB-GMA) composites, and then organic guanidine was bound on the magnetic matrices via covalent bonds with active epoxy groups. The characterization of the as-made magnetic copolymer support and solid base catalysts was performed by several techniques, and the results revealed that the guanidine base was successfully tethered on the magnetic copolymer support. This developed solid catalyst possessed large surface basicity of 2.45 mmol/g and highly magnetic responsiveness with saturation magnetization value of 18.13 emu/g, displaying good activity to the transesterification of soybean oil to biodiesel in a heterogeneous manner. Under the transesterification conditions of methanol/oil molar ratio of 20:1, catalyst dosage of 7 wt%, reaction temperature of 65 °C, reaction duration of 8 h, the biodiesel yield of 92.6% was attained over the guanidine-based solid catalyst. Moreover, the catalyst could be easily separated under an external magnetic field, and showed satisfactory catalytic activity even after four reuse cycles, thus posing considerable potential for the sustainable and clean production of biodiesel. [Display omitted] [ABSTRACT FROM AUTHOR]

The development of efficient and reusable catalysts is desired to improve biodiesel production process. For this purpose, the magnetic Fe 3 O 4 /ZIF-8 composites were first prepared by incorporating ZIF-8 MOF into Fe 3 O 4 nanoparticles through in-situ approach, and then a vanadium-substituted heteropolyacid (HPA), H 6 PV 3 MoW 8 O 40 , was encapsulated in the support to afford the solid catalyst. The so-prepared catalysts were characterized by using XRD, FT-IR, TEM, SEM, TG, VSM, and nitrogen porosimetry measurement. Results revealed that the Fe 3 O 4 /ZIF-8 support was really formed, and the HPAs had been loaded on the magnetic composite. The catalytic performances of the developed catalysts were evaluated for the heterogeneous biodiesel production from the low-quantity oils. This catalyst had good magnetic responsiveness, and could catalyze the transesterification of soybean oil and esterification of free fatty acids (FFAs) simultaneously, thus achieving one-step transformation of triglycerides and FFAs to biodiesel in a heterogeneous manner. The transesterification conversion obtained was 92.6% with 30:1 methanol/oil molar ratio at a catalyst loading of 6 wt% and reaction temperature of 160 °C for 10 h. Moreover, the solid catalyst could be recycled by an external magnet, and displayed a good reusability with a minimal mass loss and a slight decrease in the activity after reuse for five runs. This protocol showed great potential for sustainable biodiesel production from the low-quantity oils due to the pronounced activity and good reusability of the solid catalyst. Image 1 • Magnetic composite catalysts were synthesized and characterized. • The catalyst was effective for one-pot biodiesel production from low-quality oils. • The catalyst could be used for five times with no significant loss of activity. • The catalyst could be easily recovered by using an external magnetic field. [ABSTRACT FROM AUTHOR]

For the purpose of fabricating an efficient solid acid catalyst for biodiesel production from low-grade acidic oils, bimetallic silica mesoporous composites with different Zr/Al molar ratios were initially synthesized via a facile one-step hydrothermal method, and then sulfated with sulfuric acid at different concentrations to get a series of sulfated Zr x -Al y -KIT-6 catalysts (denoted as SZA-K, where x/y represents the molar ratio of Zr to Al). The sulfated bimetallic solid catalysts were fully characterized by using XRD, FT-IR, TEM, SEM, EDS, NH 3 -TPD, and nitrogen porosimetry measurements. Results showed that the remarkable amount of acidic sites in the catalysts was derived from the Zr and Al incorporation and further sulfation, and specifically, the Zr4+ and Al3+ could afford abundant weak acid sites while the inductive effect of SO 4 2− species greatly influences the acidic strength of this solid catalyst. In combination with the enhancement in mass transfer resulting from the inherent interconnected mesoporous structure, the SZA-K catalyst could facilitate the transesterification reaction to take place efficiently. The sulfated Zr 5 –Al 1 -KIT-6 catalyst (Zr/Al molar ratio of 5/1, treated using 0.75 mol/L sulfuric acid for 12 h) exhibited enhanced acid strength with larger number of acidic sites (7.81 mmol/g), resulting in a high catalytic performance to the oil transesterification reaction. An oil conversion of 96.3% was attained for the transesterification reaction performed at 120 °C for 7 h by using a methanol/oil molar ratio of 20:1 and a catalyst dosage of 6 wt%. Further, this solid catalyst exhibited better acid and water-resistance capacity with above 80% of oil conversion even with 10% of free fatty acid (FFA) and 2% of moisture present in the low-grade acidic oils. Meanwhile, the good reusability was shown for this catalyst with 80.1% conversion even after reusing for three cycles. The good stability of the solid catalyst was resulted from the strong interactions between the acidic species and the bimetallic composite support. Bimetallic Zr x -Al y -KIT-6 modified with sulfate as acidic catalyst for biodiesel production from low-grade acidic oils. [Display omitted] [ABSTRACT FROM AUTHOR]

The development of a magnetically recyclable immobilized lipase for enzymatic biodiesel production is of great research value to meet the need of green and sustainable development. In this work, the organic copolymer, poly(glycidyl methacrylate- co -methacrylic acid) (poly(GMA- co -MAA)), was encapsulated onto the Fe 3 O 4 nanoparticles, and then Candida rugosa lipase was bound on the magnetic composites through coupling reactions with epoxy and carboxyl groups. The Fe 3 O 4 -poly(GMA- co -MAA) composite and immobilized lipase were characterized by several techniques, including enzyme activity assay, FT-IR,XRD,SEM,TEM,XPS,VSM and nitrogen adsorption–desorption techniques. Results revealed that the Fe 3 O 4 -poly(GMA- co -MAA) composites were successfully synthesized, and the lipase had been anchored on the magnetic composites with the lipase binding efficiency of 88.7% and activity recovery of 67.3%. The immobilized lipase displayed well-defined structure and good magnetic responsibility with saturation magnetization of 28.73 emu/g, and furthermore showed high catalytic activities to the transesterification of soybean oil. The biodiesel yield of 92.8% was attained through three-step addition of methanol at 40 °C with this magnetic biocatalyst. The immobilized lipase is recovered facilely by magnetic separation, still retaining at 79.4% of biodiesel yield after reuse for five cycles, and thus highlighting its great potential in the sustainable production of biodiesel. • Lipase was covalently bound onto Fe 3 O 4 -poly(GMA- co -MAA) composites. • The immobilized lipase could give the biodiesel yield of 92.8%. • The immobilized lipase is facilely recovered using an external magnetic field. [ABSTRACT FROM AUTHOR]

In accordance with the need of green and sustainable development, a magnetically recyclable solid catalyst was developed for the transformation of low-cost oils to biodiesel via simultaneous transesterification and esterifications in an efficient and environmentally benign manner. For this aim, the magnetic Fe 3 O 4 /SiO 2 composites composed of iron oxides as the core and silica as the shell, were prepared, and then polymeric acidic ionic liquid (IL) was immobilized on the magnetic support through radical grafting copolymerization of Brønsted acidic IL, 1-vinyl-3-(3-sulfopropyl)imidazolium hydrogen sulfate, onto the magnetic support. The characterization results showed that the perfect core-shell structured Fe 3 O 4 /SiO 2 support with good magnetic responsiveness was formed, and the polymeric acidic IL was tethered on the magnetic support. The combination of polymeric acidic IL with magnetic porous nanoparticles could enhance the catalytic activity and favored the separation performance of the catalyst. The solid catalyst exhibited high activities for both transesterification of soybean oil and esterification of free fatty acids generally presented in low-cost oils. Moreover, the catalyst could be simply recovered magnetically and efficiently reutilized for several times without significant loss in its activity, thus allowing its being potentially applicable for green and economic production of biodiesel especially from the low-cost oil feedstocks. • A magnetically recyclable catalyst with core–shell structure was prepared. • The catalyst was used for one-pot biodiesel production from low-cost oils. • The catalytic activity and durability were intensively explored. [ABSTRACT FROM AUTHOR]

An efficient and recyclable catalyst, namely phosphomolybdenum-based sulfonated ionic liquids (ILs) functionalized MIL-100(Fe) metal–organic framework (AIL/HPMo/MIL-100(Fe)), was developed for the production of biodiesel via the transesterification-esterifications of acidic oils. For this goal, the MIL-100(Fe) metal–organic framework (MOF) was initially modified with phosphomolybdic acid (HPMo), and then the acidic ionic liquid (AIL) was immobilized on the prepared HPMo/MIL-100(Fe) composite through ion-exchange of 1-(propyl-3-sulfonate)imidazolium hydrogen sulfate with HPMo. The as-developed AIL/HPMo/MIL-100(Fe) catalyst possessed enhanced surface acidities, endowing the merits of Lewis and Brönsted acids with a heterogeneous microreactor of MOFs and favoring the better catalytic performance. The characterization results corroborated that the polyoxometalate-based ILs were incorporated into the MIL-100(Fe), and the porous structure of the MIL-100(Fe) maintained nearly unchangeable after the synthesis processes. The AIL/HPMo/MIL-100(Fe) catalyst could perform simultaneous transesterification of soybean oil and esterification of free fatty acids (FFAs) with long-term catalytic durability. The conversion of acidic oils using this solid catalyst gave 92.3% oil conversion for the transesterification of soybean oil and full FFA conversion for the esterification of FFAs with the methanol/oil molar ratio of 30:1 at 120 °C, showing potential applications for the production of biodiesel particularly from acidic oil feedstocks. Synopsis: Phosphomolybdenum-based sulfonated ionic liquids (ILs) functionalized MIL-100(Fe) metal–organic framework composites are fabricated and then utilized as efficient and recyclable catalysts for the production of biodiesel via one-pot transesterification-esterifications of acidic oils. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • AILs/HPW/UiO-66-2COOH catalysts with both Brönsted and Lewis acid site were prepared. • The catalyst was effective for one-pot biodiesel production from low cost oils. • The solid acid catalysts were fully characterized by various techniques. • The catalytic activity and stability of the catalysts were intensively investigated. Abstract In accordance with the need of green and cleaner production, the aim of the present study is to fabricate an organic-inorganic hybrid recyclable catalyst with both Brönsted and Lewis acid sites for the one-pot production of biodiesel from the low-cost acidic oil feedstocks. To achieve this, the UiO-66-2COOH metal-organic framework materials (MOFs) were firstly functionalized with Keggin-type polyoxometalate (POM) acids through the in-situ preparation strategy, and then the sulfonated acidic ionic liquids (AILs) were further incorporated into the prepared POM/UiO-66-2COOH composites by pairing polyoxometalate anions with functionalized IL cations. The as-prepared AILs/POM/UiO-66-2COOH solid catalyst features a high surface area and an increased acidity, thus combining the merits of Brönsted and Lewis acids together with the heterogeneous microenvironment of MOFs. The solid acid catalysts were fully characterized by several techniques, and the results demonstrated that the polyoxometalate-based sulfonated AILs were virtually immobilized on the UiO-66-2COOH MOFs, and furthermore the porous crystalline structure of the UiO-66-2COOH material was almost unaltered after the immobilization processes. The solid catalyst had excellent catalytic activities toward the simultaneous transesterification and esterification of simulated low-cost oils with long-term stability and good reusability, and moreover still remained considerable activities even with the existence of 9 wt% free fatty acid and 3 wt% water in the low-cost oils. Therefore, this solid catalyst shows potential applications for the one-step biodiesel production especially from the low-cost feedstocks which usually contain high amounts of free fatty acid and water. [ABSTRACT FROM AUTHOR]

This study aims at the development of magnetically recyclable solid catalysts for the production of biodiesel. To achieve this, the magnetically susceptible Fe 3 O 4 /MCM-41 composites with core-shell structure were prepared, and sodium silicate was then supported on the magnetic materials by using epichlorohydrin as a cross-linking reagent. The core-shell structured magnetic support and so-prepared solid catalyst were characterized by various techniques. Characterization results showed that the sodium silicate was chemically bridged onto the Fe 3 O 4 /MCM-41 composites without obvious damage to the structure of the magnetic support. The solid catalyst exhibited a strong magnetic response and displayed extraordinary catalytic activities in the transesterification of soybean oil for the production of biodiesel, with the oil conversion reaching 99.2% by using the methanol-to-oil molar ratio of 25:1 and catalyst loading of 3 wt% at reflux of methanol after 8 h of reaction. Moreover, the separation of the solid catalyst from reaction mixture was readily achieved by simple magnetic decantation without obvious mass loss, and the solid catalyst could be reused for five times for the heterogeneous transesterification. [ABSTRACT FROM AUTHOR]

The main objective of this study is to develop an efficient and environmentally gentle process for production of trans -free plastic fats. To acheive this, the core–shell structured magnetic composites were prepared, and then imidazole-based ionic liquids (ILs) were covalently grafted on the magnetic composites. Thereafter, Candida rugosa lipase was immobilized on the magnetic IL-functionalized composites. The immobilized lipase could be facilely separated using an external magnetic filed. With the magnetic biocatalyst, enzymatic interesterifications of solid palm stearin and liquid rice bran oil blends were performed at 45 °C. It was shown that the total fatty acid (FA) compositions of the binary blends were almost unchanged after the interesterifications, whereas the FA positional distribution and triacylglycerol species were significantly varied. As compared with the physical blends, the interesterified products had a lower slip melting point, and the interesterification could result in an obvious change in the microstructure of the final products. [ABSTRACT FROM AUTHOR]

The purpose of this work is to develop robust and stable catalysts for production of low-calorie lipids in a heterogeneous manner to meet the demand of green food engineering. To accomplish this, magnetic Fe 3 O 4 @SiO 2 support was prepared, and then dual acidic ionic liquid, 1-(propyl-3-sulfonate)imidazolium hydrogen sulfate, was bound onto the magnetic support via covalent attachments to prepare solid acid catalysts. The so-prepared solid catalyst was characterized by Brönsted acidity determination, elemental analysis, XRD, FT-IR, TEM, VSM, and N 2 adsorption-desorption techniques. Results showed that the ionic liquid was successfully immobilized on the Fe 3 O 4 @SiO 2 support, and the structure of magnetic support remained unchangeable after the functionalization. This solid catalyst displayed a strong magnetic responsiveness, allowing it to be easily separated by an external magnet. By using this magnetic catalyst, soybean oil was acidolyzed with caprylic and capric acids to produce medium-chain structured lipids. The medium-chain fatty acids incorporated into triacylglycerols were determined by GC techniques, and the total incorporations of caprylic and capric acids were found to be 42.5% over the catalyst. Moreover, the solid catalyst could be reused efficiently for several cycles without appreciable loss of its activity. [ABSTRACT FROM AUTHOR]

The main purpose of this present work is to fabricate a magnetically recyclable solid catalyst for the production of biodiesel to meet the demand of green and clean production. To accomplish this, the core–shell structured Fe 3 O 4 @HKUST-1 composites with a magnetic core and a porous metal-organic framework shell were fabricated by using a versatile Layer-by-Layer assembly method, and then basic ionic liquids were encapsulated within the core–shell magnetically responsive material, resulting in a solid hybrid base catalyst. Various techniques such as XRD, TEM, FT-IR, VSM and nitrogen adsorption–desorption were employed to characterize the as-prepared solid base catalyst. The characterization results revealed that Fe 3 O 4 nanoparticles were well coated with metal-organic framework HKUST-1 with the formation of core–shell structured nanocomposites, and moreover the basic ionic liquid had been successfully encapsulated within the magnetic nanocomposites. Furthermore, the solid base catalysts possessed superparamagnetic behavior and high saturation magnetization, allowing them to be facilely separated from the reaction mixture by using an external magnetic filed. The solid base catalyst appeared to be an efficient and environmentally benign catalyst for the transesterification of soybean oil with methanol for the production of biodiesel, giving 92.3% oil conversion to methyl esters within 3 h with a catalyst loading of 1.2 wt% and a methanol/oil molar ratio of 30:1 at reflux temperature of methanol. The solid catalyst could be readily recovered by simple magnetic decantation and reused for several times without significant degradation in its catalytic activity. [ABSTRACT FROM AUTHOR]

The purpose of this work is to develop a magnetically recyclable immobilized lipase for biodiesel production to meet the need of green and clean production. To achieve this, magnetic Fe 3 O 4 nanoparticles were encapsulated in graphene oxides (GO), and then employed as a magnetic carrier for the immobilization of lipase from Candida rugosa via the interfacial activation of enzyme on hydrophobic surfaces. By using this immobilization strategy, the activity recovery of 64.9% and enzyme immobilization efficiency of 85.5% could be achieved. The as-prepared graphene oxide Fe 3 O 4 nanocomposite (MGO) and immobilized lipase microsphere were fully characterized by means of enzyme activity assays, transmission electron microscopy (TEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, vibrating-sample magnetometer (VSM) and nitrogen adsorption–desorption techniques. It was shown that the Fe 3 O 4 nanoparticles were successfully encapsulated into the GO, and moreover the lipase was tethered on the magnetic support. The immobilized lipase could efficiently catalyze the transesterification of soybean oil with methanol for the production of biodiesel. With this magnetic biocatalyst, the biodiesel yield of 92.8% could be obtained at a temperature of 40 °C by three-step addition of methanol in a shaking water bath. The immobilized lipase could be easily recovered by using an external magnetic field, allowing for recycling of the biocatalyst five times without significant loss of its activity. [ABSTRACT FROM AUTHOR]

The main purpose of the present research is to develop an environmentally more attractive process for the production of biodiesel by using a magnetic separable solid catalyst. To achieve this, hydroxyapatite-encapsulated γ-Fe 2 O 3 nanoparticles (HAp-γ-Fe 2 O 3 ) were prepared, and organic biguanide was then bound to the magnetic carrier via covalent attachments. The magnetic carrier and biguanide-functionalized HAp-γ-Fe 2 O 3 were fully characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectra, energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), vibrating-sample magnetometer (VSM) and nitrogen adsorption–desorption techniques. Results demonstrated that the biguanide was successfully immobilized on the HAp-γ-Fe 2 O 3 without damage to the morphology and structure of the HAp-γ-Fe 2 O 3 carrier. The so-prepared inorganic-organic hybrid nanocomposites exhibited a strong magnetic response and displayed better catalytic activities in the transesterification of soybean oil with methanol for the production of biodiesel. By using the methanol/oil molar ratio of 25:1 and catalyst loading of 3 wt%, the maximum oil conversion of 99.6% was achieved over the solid base catalyst at reflux of methanol after 3 h of reaction. Further, the solid catalyst could be recovered facilely by simple magnetic separation and maintains satisfactory catalytic activity after being recycled for five times. [ABSTRACT FROM AUTHOR]

The Keggin-type CsHPWO was encapsulated in metal-organic framework UiO-66 by a simple solvothermal synthesis method. The characterization results showed that the morphology and crystal structure of UiO-66 were preserved, and the heteropolyanion structure remained unchanged after CsHPWO encapsulation. The prepared CsHPWO@UiO-66 material has demonstrated to be an environmentally benign catalyst in the acidolysis of soybean oil with medium-chain fatty acids for the production of low-calorie structured lipids. The FT-IR CO adsorption experiments revealed that additional Lewis acid sites were formed in the solid acid catalyst, which were essential to catalyze the acidolysis reaction. The solid catalyst could be reused for several recycles without obvious deactivation due to hardly leaching of active components into the reaction mixture. Graphical Abstract: [ABSTRACT FROM AUTHOR]

Hydroxyapatite-encapsulated γ-Fe 2 O 3 nanoparticles were prepared, and lipase from Candida rugosa was then covalently bound onto the magnetic materials via covalent linkages. The magnetic carrier and immobilized lipase were characterized by enzyme activity assays, XRD, FT-IR, TEM, VSM and N 2 adsorption–desorption techniques. Results demonstrated that γ-Fe 2 O 3 nanoparticles were coated with the hydroxyapatite, and the lipase was indeed tethered to the magnetic carriers without damage to their structure. The immobilized lipase showed a strong magnetic responsiveness and displayed high catalytic activities towards the interesterification of soybean oil. The interesterified products were evaluated for their total fatty acid (FA) composition, slip melting point (SMP), iodine value, triacylglycerols (TAGs) profile and FA composition at sn -2 position in TAGs. The FA positional distributions and TAG species significantly changed after the enzymatic interesterification. Besides this, the interesterified products showed an obvious reduction in their SMP in comparison with the physical blends. [ABSTRACT FROM AUTHOR]

Ameliorating the reactant mass transfer and fabricating the multiple active sites on the catalyst surface are feasible strategies to synthesize efficient and recyclable catalysts for efficient biodiesel production by using acidic oils as feedstocks. Herein, hierarchical porous solid acids with Zr and Mo oxides as active sites were prepared by using polystyrene spheres (PS) and P123 as templates. It was shown that the active species of Zr and Mo oxides were uniformly dispersed on the hierarchical porous silica support, and the solid catalysts featured high surface area and interconnected mesoporous/macropores with high mass diffusive extent, showing improved catalytic performances for the biodiesel production as compared to the control catalyst without hierarchical pores, owing to the mass transfer enhancement and more easily accessible active sites. The transesterification reaction in 93.8% of oil conversion as well as complete conversion of free fatty acids (FFAs) were simultaneously performed by using this solid catalyst, hence achieving one-pot transformation of acidic oils to biodiesel and minimizing the complex and tedious separation process. Moreover, the higher water and FFA-resistance capacity was shown for this solid catalyst, posing its more suitable for the biodiesel production with acidic oils as feedstocks. This hierarchical porous solid catalyst could be facilely recycled using simple filtration, and still maintained high activities after reuse for five runs, which rendered it to have the potential of cost-effective production of biodiesel in particular from low-grade acidic oils. [Display omitted] • Novel hierarchical porous ZrMo-MmSiO 2 catalysts with Zr and Mo oxides were prepared. • The hierarchical networks improve the mass diffusion and active site accessibility. • Transesterification and esterification reactions can be achieved simultaneously. • The catalyst has good recyclability and high resistance to free fatty acid and water. [ABSTRACT FROM AUTHOR]

Biodiesel has attracted widespread attention as a potential alternative energy source to fossil-derived fuels. The application of heterogeneous catalysts for biodiesel production can offer an environmentally-friendly more attractive process for sustainable and cleaner production requirement. Small-sized heterogeneous catalysts generally show better activities due to their higher surface area and less mass transfer limitation. However, the separation of theses solid catalysts is particularly difficult; and the serious mass loss during the separation process together with more time- and energy-consumption precludes their practical utilization especially for high viscosity reaction mixtures. Magnetic solid catalysts have recently become the research hotpot for the transesterification and esterifications for biodiesel production, because of their easy separation with minimal mass loss by an external magnetic field. In this review, various magnetic solid catalysts, including magnetic solid acid, alkali, enzyme and acidic-basic bi-functional catalysts were introduced. The catalyst preparation, catalytic performances, reaction mechanism, and recyclability of the catalysts and their influential parameters with some justifications are discussed from previous literatures to the field of interest, mainly focusing on the influence of active species, surface properties and their synergisms on the catalytic performances. For achieving the goal of good progress in efficient biodiesel production, the evaluation of the present research state, the challenge faced by the magnetic catalysts and future development trend are put forward. Possible reaction mechanisms for different types of the catalysts are also presented, giving some critical guidance in the design of magnetic solid catalysts. Finally, the key influential parameters on the catalytic performances as well as current challenges and future perspectives are provided for further improvement. [Display omitted] • Frontline magnetic solid catalysts are explored in biodiesel production. • Influential parameters with some justifications are extensively discussed. • Current challenges and opportunities for future research are highlighted. [ABSTRACT FROM AUTHOR]

The objective of this work was to develop a feasible ecofriendly process to produce medium-chain fatty acid (MCFA)-enriched structured lipids (SLs) in heterogeneous manners. For this purpose, the propyl-SO 3 H or arene-SO 3 H-modified SBA-15 materials were prepared through a surface functionalization of SBA-15 silica with propyl-SO 3 H and arene-SO 3 H groups. The organosulfonic acid-functionalized SBA-15 materials were characterized by Brönsted acidity determination, elemental analysis, XRD, C 13 MAS NMR, FT-IR, SEM, TG, TEM, and N 2 adsorption-desorption techniques. Results showed that the propyl-SO 3 H and arene-SO 3 H groups were successfully tethered on the SBA-15 support, and the ordered mesoporous structure of SBA-15 silica was well retained after the organofunctionalization. This organic-inorganic hybrid material displayed high surface acidities and high activities in the acidolysis of soybean oil with caprylic or capric acid to produce SLs containing MCFAs. The influences of processing parameters on the reaction were investigated. The two studied catalysts showed an excellent recyclability for the reaction. [ABSTRACT FROM AUTHOR]

The biguanide-functionalized SBA-15 materials were fabricated by grafting of organic biguanide onto the SBA-15 silica through covalent attachments, and then this organic–inorganic hybrid material was employed as solid catalysts for the interesterification of triacylglycerols for the modification of vegetable oils. The prepared catalyst was characterized by FTIR, XRD, SEM, TEM, nitrogen adsorption–desorption and elemental analysis. The biguanide base was successfully tethered onto the SBA-15 silica with no damage to the ordered mesoporous structure of the silica after the organo-functionalization. The solid catalyst had stronger base strength and could catalyze the interesterification of triacylglycerols. The fatty acid compositions and triacylglycerol profiles of the interesterified products were noticeably varied following the interesterification. The reaction parameters, namely substrate ratio, reaction temperature, catalyst loading and reaction time, were investigated for the interesterification of soybean oil with methyl decanoate. The catalyst could be reused for at least four cycles without significant loss of activity. [ABSTRACT FROM AUTHOR]

A core–shell structured Fe 3 O 4 –MCM-41 nanocomposite was prepared by means of a surfactant-directed sol–gel process. Candida rugosa lipase was then bound to the magnetic core–shell material by using glutaraldehyde as a cross-linking reagent. The as-prepared Fe 3 O 4 –MCM-41 support and the immobilized lipase were characterized in detail using enzyme activity assays, TEM, XRD, FTIR, VSM and nitrogen adsorption–desorption techniques. Results showed that the magnetite nanoparticles were coated with the MCM-41 silica with the formation of core–shell structured materials, and the lipase was successfully immobilized on the core–shell structured support. The catalytic performance of the bound lipase was tested in the interesterification of lard and soybean oil. It was shown that the immobilized lipase had a better catalytic activity towards the interesterification reaction. The slip melting point of the final product was lower than that of the original blend, and the interesterification led to an obvious variation in the microstructure of the product. [ABSTRACT FROM AUTHOR]

Heterogeneous transesterification of vegetable oils offers an environmentally more attractive option for biodiesel production compared to the conventional homogeneous processes. In the work, a novel heterogeneous base catalyst was prepared by anchoring 1,3-dicyclohexyl-2-octylguanidine (DCOD) onto the mesoporous SBA-15 silica. The DCOG-functionalized SBA-15 material (SBA-15-pr-DCOG) was demonstrated to be an efficient and recyclable heterogeneous catalyst for the transesterification of soybean oil with methanol. The characterization of the catalyst was carried out using Hammett titration method, X-ray diffraction, Fourier transform infrared spectroscopy, thermo gravimetric and differential thermal analysis, transmission electron microscopy, X-ray photoelectron spectroscopy, nitrogen adsorption–desorption techniques. It was shown that the DCOD was successfully tethered on the SBA-15 silica and ordered mesoporous structure of SBA-15 was largely remained unchanged after the functionalization reaction. The influences of transesterification variables such as the methanol/oil molar ratio, catalyst loading, reaction time, and catalyst reusability on the oil conversion were investigated. By using the methanol/oil molar ratio of 15:1 and catalyst loading of 8 wt.%, the maximum oil conversion of 92.6% was achieved over the solid catalyst at reflux of methanol for 15 h. The heterogeneous base catalyst could be easily recovered and reused for several runs with a negligible loss of activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • 35% H 6 PV 3 MoW 8 O 40 /AC-Ag catalyst was prepared. • A high oil conversion of 91.3% was achieved over the solid catalyst. • The catalyst has good recyclability and high resistance of acid and water. • Transesterification and esterification reactions can be achieved simultaneously. The heterogenization of Keggin-structure heteropoly acids (HPAs) has been proposed as a strategy to improve their application in biodiesel production in an attempt to comply the green and clean production demand. Herein, the commercial activated carbon (AC) was firstly modified with different metal ions (Cs+, K+ and Ag+), and then the H 6 PV 3 MoW 8 O 40 acid was incorporated into as-modified AC supports, so as to prepare HPAs-based solid catalysts. By screening tests, the 35%H 6 PV 3 MoW 8 O 40 /AC-Ag hybrid solid catalyst showed highly catalytic performance for transesterification of soybean oil. The best oil conversion of 91.3% was achieved under optimized conditions: methanol/oil molar ratio of 30:1, reaction time of 10 h, reaction temperature of 140 °C and catalyst dosage of 8 wt.%. Characterization results of XRD, IR, ICP and TG indicated that H 6 PV 3 MoW 8 O 40 was highly dispersed on the AC-Ag support as the loading was less than 35%. Proton exchange with Ag may contribute to the highly dispersion of H 6 PV 3 MoW 8 O 40 on the support and thus enhance the interaction of the heteropoly acids with the support, thereof leading to the increased catalytic stability. The as-prepared 35%H 6 PV 3 MoW 8 O 40 /AC-Ag catalyst was easily recycled and had good resistance to free fatty acid (FFA) and water, which were usually included in the low-quality oils. Moreover, as a bifunctional catalyst, the solid acid catalyst could simultaneously catalyze the transesterification of soybean oil and esterification of FFAs, and a probable mechanism of the catalytic process was also proposed. All the features of this novel solid catalyst are more advantageous than the homogenous H 6 PV 3 MoW 8 O 40 catalyst, successfully creating an efficient and sustainable approach of biodiesel production especially from the low-quality oils. [ABSTRACT FROM AUTHOR]

Inthe present study, SBA-15 silica-supported basic ionic liquidwas prepared through grafting of 4-butyl-1,2,4-triazolium hydroxideonto SBA-15 silica using 3-chloropropyltriethoxysilane as a couplingreagent. The structural properties of the prepared catalysts wereinvestigated by a series of techniques, such as Hammett titrationmethod, elemental analysis, small angle XRD, FT-IR, SEM, TEM, andN2adsorption–desorption. The characterization resultsdemonstrated that the ionic liquid was successfully tethered on theSBA-15 support, and the hexagonally ordered mesoporous structure ofSBA-15 silica was well retained even after the chemical grafting reaction.The so-obtained solid catalyst showed excellent catalytic activitiestoward the transesterification of soybean oil with methanol to producebiodiesel in a heterogeneous manner. The influences of various transesterificationparameters such as the subtract ratio, reaction time, catalyst amount,and catalyst reusability on the oil conversion to methyl esters wereinvestigated systematically. Using this solid catalyst for the transesterificationreaction, the high conversion of 95.4% was achieved at reflux of methanolfor 8 h when the methanol/oil molar ratio of 20:1 and catalyst loadingof 7 wt % were employed. Moreover, the solid catalyst could be recycledfor four cycles without significant degradation of catalytic activity. [ABSTRACT FROM AUTHOR]

Highlights: [•] Solid catalysts were used for biodiesel production in a heterogeneous manner. [•] The catalyst could give the oil conversion of 83.2%. [•] The catalyst was characterized by using various techniques. [Copyright &y& Elsevier]

Highlights: [•] Solid catalysts were prepared and employed for soybean oil transesterification. [•] The catalysts were characterized by using various techniques. [•] The catalytic activity and stability of the catalyst were investigated. [ABSTRACT FROM AUTHOR]

Abstract: In this work, the phenylsulfonic acid functionalized SBA-15 silica was prepared by the reaction of mesoporous SBA-15 silica with phenyltrimethoxysilane, followed by the sulfonation with chlorosulfonic acid. The functionalized SBA-15 silica was then tested as a heterogeneous acid catalyst in the esterification of free fatty acid (FFA) present in vegetable oils with methanol. The textural feature and structure of the solid catalyst were investigated by using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), small-angle X-ray scattering (SAXS), thermo gravimetric analysis (TG) and nitrogen adsorption–desorption techniques. When 7wt.% of the solid catalyst and 15:1M ratio of methanol to oil were used in the esterification reaction, the FFA conversion to methyl esters of 96.7% was attained after 5h of reaction at a temperature of 67°C. It is shown that the heterogeneous acid catalyst possesses a good stability. [Copyright &y& Elsevier]

Highlights: [•] Heterogeneous catalysts were prepared by an impregnation method with different conditions. [•] The catalysts were efficient in the soybean oil transesterification. [•] The catalytic activity and stability of the catalyst were investigated. [ABSTRACT FROM AUTHOR]

Highlights: [•] Solid catalysts were prepared and employed for soybean oil transesterification. [•] The catalysts were characterized by using different techniques. [•] The catalytic activity and stability of the catalyst were investigated. [ABSTRACT FROM AUTHOR]

Abstract: The transesterification of soybean oil with methanol to fatty acid methyl ester (FAME) was carried out using WO3/SnO2 solid as a heterogeneous acid catalyst. The effects of catalyst preparation parameters on the conversion to FAME were investigated. This WO3/SnO2 catalyst prepared by an impregnation method, with the WO3 loading amount of 30% and calcined at a temperature of 1173K, showed the best catalytic activity. The maximum conversion to FAME of 79.2% was achieved after 5h at 383K when 30:1M ratio of methanol to oil and 5wt.% of catalyst were employed. The ability of the catalyst to esterify free fatty acids (FFAs) in feedstocks and its insensitivity to water exhibited the potential to prepare biodiesel from low-cost feedstocks. The solid catalyst can be reused for four runs without significant deactivation. [Copyright &y& Elsevier]

Abstract: In this study, 3-aminopropylsilica was prepared by a reaction of silica gel with 3-aminopropyl(trimethoxy)silane, and used as a heterogeneous catalyst for soybean oil transesterification with methanol. This 3-aminopropylsilica catalyst was characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), thermo gravimetric and differential thermal analysis (TG–DTA) and nitrogen adsorption–desorption technique. The transesterification conditions, such as the molar ratio of methanol to oil, reaction temperature, reaction time, and catalyst dosage were investigated. It was shown that the conversion of soybean oil to methyl esters could reach 94.5% when the reaction was performed with a molar ratio of methanol to soybean oil of 30:1, a catalyst amount of 8wt.%, at a reaction temperature of 423K. The free fatty acid and water present in the feedstocks decreased the catalyst activity in the transesterification reaction. The heterogeneous catalyst could be recovered with a better reusability. [Copyright &y& Elsevier]

Abstract: WO3/AlPO4 catalysts were prepared by impregnation of AlPO4 with ammonium metatungstate. Powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and thermo gravimetric and differential thermal analysis (TG–DTA) demonstrated that the tungsten compound was incorporated into AlPO4 forming the catalyst with an enhanced acidity. When transesterification of soybean oil over the catalysts was performed, the catalyst with 30wt.% WO3 loading and calcined at 1073K, exhibited the best catalytic activity with a conversion of 72.5%. The transesterification was optimal at 453K for 5h with a methanol/oil ratio of 30:1 and catalyst dosage of 5wt.%. Free fatty acid (FFA) and water did not affect the catalytic activity. The catalyst proved to be stable over four transesterification cycles as it lost only 4% of its activity after being reused four times. The catalyst could be used for the transesterification of low-cost oils for biodiesel production. [Copyright &y& Elsevier]

An effective heterogeneous catalyst, CaMgO, was prepared and tested for soybean oil transesterification with methanol. The catalysts were characterized by using X-ray diffraction , Fourier transform infrared spectra, thermo gravimetric and differential thermal analysis , and Hammett indicator method. The catalyst with Ca/Mg ratio of 1.0 and calcined at 800 °C exhibited high catalytic activities. Under the suitable transesterification conditions (methanol/oil ratio 12:1, catalyst loading 6 wt%, reaction time 5 h, at reflux of methanol), the oil conversion of 91.3% could be achieved. The catalyst can be easily recovered and reused without significant deactivation. Graphical Abstract: Biodiesel can be produced by transesterification of soybean oil to methyl esters using CaMgO catalyst in a heterogeneous manner[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: Biodiesel fuel, produced by transesterification of vegetable oils or animal fats with methanol, is a promising alternative diesel fuel due to the limited resources of fossil fuels and the environmental concerns. An environmentally benign process for the transesterification reaction using immobilized lipase has attracted considerable attention for biodiesel production. In the work, magnetic chitosan microspheres were prepared by the chemical co-precipitation approach using glutaraldehyde as cross-linking reagent for lipase immobilization. The immobilization of lipase onto the magnetic particles was confirmed by magnetic measurements, transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) spectra. Using the immobilized lipase, the conversion of soybean oil to fatty acid methyl esters reached 87% under the optimized conditions of methanol/oil amount-of-substance ratio 4:1 with the three-step addition of methanol, reaction temperature 35 °C, and reaction duration 30 h. Moreover, the immobilized lipase could be used for four times without significant decrease of the activity. [Copyright &y& Elsevier]

Abstract: The transesterification of soybean oil with methanol was carried out, to produce biodiesel, over silica-bonded N-propyl sulfamic acid in a heterogeneous manner. Results showed that a maximum conversion of 90.5% was achieved using a 1:20M ratio of soybean oil to methanol and a catalyst amount of 7.5wt.% at 423K for 60h. It was found that the free fatty acid (FFA) and water present in the feedstock had no significant influence on the catalytic activity to the transesterification reaction. Besides, the catalyst also showed activities towards the esterification reaction of FFAs, in terms of the FFA conversion of 95.6% at 423K for 30h. Furthermore, the catalyst could be recovered with a better reusability. [Copyright &y& Elsevier]

Abstract: An ionic liquid, namely 1-butyl-3-methylimidazolium chloride (BMIMCl), was employed as a reaction medium for homogenous carboxymethylation of corn starch. The process variables affecting the carboxymethylation reaction such as amount of sodium hydroxide (NaOH) and sodium monochloroacetate (SMCA), reaction time and reaction temperature were investigated regarding the degree of substitution (DS) for the carboxymethyl starch. The highest DS of 0.76 was obtained at molar ratios of NaOH and SMCA to anhydroglucose unit (AGU) of 1.2 and 1.0, respectively, and at 90°C for 3h of reaction. Results from FT-IR and 13C NMR spectra indicated that the hydroxyl groups of starches were substituted by carboxymethyl groups. SEM and XRD studies showed that the morphology and crystallinity of starch was disrupted after the carboxymethylation reaction. [Copyright &y& Elsevier]

Abstract: Lipase was covalently immobilized onto magnetic Fe3O4 nano-particles by using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) as an activating agent, and the bound lipase was used to catalyze the transesterification of vegetable oils with methanol to produce fatty acid methyl esters. The binding of lipase to magnetic particles was confirmed by enzyme assays, transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) spectra. It was determined that the immobilized lipase exhibited better resistance to temperature and pH inactivation in comparison to free lipase. Using the immobilized lipase, the major parameters affecting the transesterification reaction, such as the alcohol/oil molar ratio, enzyme loading and free fatty acid present in reactants were investigated to obtain the optimum reaction condition. The conversion of soybean oil to methyl esters reached over 90% in the three-step transesterification when 40% immobilized lipase was used. Moreover, the lipase catalyst could be used for 3 times without significant decrease of the activity. [Copyright &y& Elsevier]

Abstract: Cationic corn starch derivatives containing quaternary ammonium groups with a high degree of substitution were synthesized by reacting corn starch with glycidyltrimethylammonium chloride (GTAC) in a homogeneous manner using 1-butyl-3-methylimidazolium chloride (BMIMCl) as a reaction medium. The influence of reaction time, reaction temperature, the amount of catalyst NaOH and molar ratio of GTAC/anhydroglucose units in starch on the degree of substitution (DS) of products was investigated. The maximum DS value obtained in the optimum reaction condition was up to 0.99. Furthermore, the structure of cationic starch derivatives was characterized by means of Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray powder diffraction (XRD), thermal analysis and 1H NMR spectroscopy. The results showed that the ordered crystalline structure of native starch was largely destroyed during the dissolution and functionalization of starch in the ionic liquid BMIMCl, leading to an uniform etherification reaction to be carried out under the homogeneous reaction conditions. [Copyright &y& Elsevier]

Abstract: The oxidation of methyl linoleate micelles has been studied, aiming at elucidating the effect of various variables, including surfactant type, pH and antioxidants. The progress of the methyl linoleate oxidation was evaluated by measurement of conjugated dienes hydroperoxides (CDHP) and malondialdehyde (MDA). It was shown that the oxidative stability of methyl linoleate micelles was influenced by surfactant type, with oxidative rate being greater in SDS micelles than in Tween 20 micelles. Besides, the methyl linoleate micelles at pH 6.8 had greater rates of lipid oxidation than their pH 3.0 counterparts. Moreover, the incorporation of VE and VC in the methyl linoleate micelles successfully slowed the formation of hydroperoxides and their subsequent decomposition product MDA. However, the antioxidant activities of VE and VC were related to their concentrations. [Copyright &y& Elsevier]

Abstract: Fatty acid methyl esters, derived from vegetable oils or animal fats and better known as biodiesel, have received considerable attention because of their environmental benefits and the limited resources of fossil fuels. Most biodiesel is usually produced by the transesterification of vegetable oils with methanol in the presence of a catalyst. This study reports on the preliminary results of using alkaline earth metal-doped zinc oxide as a heterogeneous catalyst for transesterification of soybean oil. The highest catalytic activity was obtained with ZnO loaded with 2.5 mmol Sr(NO3)2/g, followed by calcination at 873 K for 5 h. When the transesterification reaction was carried out at reflux of methanol (338 K), with a 12:1 molar ratio of methanol to soybean oil and a catalyst amount of 5 wt.%, the conversion of soybean oil was 94.7%. Besides, tetrahydrofuran (THF), when used as a co-solvent, could increase the conversion up to 96.8%. However, the recovered catalyst exhibited the lower catalytic activity with a conversion of soybean oil of 15.4%. Furthermore, DTA-TG, IR and the Hammett indicator method were employed for the catalyst characterizations. [Copyright &y& Elsevier]

Abstract: The transesterification of soybean oil with methanol to methyl esters was carried out using NaX zeolites loaded with KOH as a solid base catalyst. Best result was obtained with NaX zeolite loaded with 10% KOH, followed by heating at 393K for 3h. When the transesterification reaction was carried out at reflux of methanol (338K), with a 10:1 molar ratio of methanol to soybean oil, a reaction time of 8h and a catalyst amount of 3wt.%, the conversion of soybean oil was 85.6%. [Copyright &y& Elsevier]

Abstract: Biodiesel fuel, a promising alternative diesel fuel produced by a catalytic transesterification of vegetable oils, has become more attractive recently because of its environmental concerns and the fact that it is made from renewable resources. In this work, the transesterification of soybean oil with methanol has been studied in a heterogeneous system, using alumina loaded with potassium iodide as a solid base catalyst. After loading KI of 35wt.% on alumina followed by calcination at 773K for 3h, the catalyst gave the highest basicity and the best catalytic activity for this reaction. The catalysts were characterized by means of XRD, IR, SEM and the Hammett indicator method. Moreover, the dependence of the conversion of soybean oil on the reaction variables such as the catalyst loading, the molar ratio of methanol to oil and the reaction time was studied. The conversion of 96% was achieved under the optimum reaction conditions. Besides, a correlation of the catalyst activity for the transesterification reaction with its basicity was proposed. [Copyright &y& Elsevier]

Abstract: Methyl ester of fatty acids, derived from vegetable oils or animal fats and known as biodiesel, is a promising alternative diesel fuel regarding the limited resources of fossil fuel and the environmental concerns. In this work, an environmentally benign process for the methanolysis of soybean oil to methyl esters using calcined Mg–Al hydrotalcites as solid base catalysts in a heterogeneous manner was developed. When the reaction was carried out at reflux of methanol, with a molar ratio of soybean oil to methanol of 15:1, a reaction time 9h and a catalyst amount 7.5%, the oil conversion was 67%. The calcined hydrotalcite with an Mg/Al ratio of 3.0 derived from calcination at 773K was found to be the optimum catalyst that can give the highest basicity and the best catalytic activity for this reaction. The catalysts were characterized with SEM, XRD, IR, DTA-TG and Hammett titration method. The activity of the catalysts for the methanolysis reaction was correlated closely with their basicity as determined by the Hammett method. [Copyright &y& Elsevier]

Abstract: Biodiesel fuel, consisting of methyl esters of long chain fatty acids produced by transesterification of vegetable oils or animal fats with methanol, is a promising alternative diesel fuel regarding the limited resources of fossil fuels and the environmental concerns. In this work, an environmentally benign process for the transesterification of soybean oil to methyl esters using alumina loaded with potassium as a solid base catalyst in a heterogeneous manner was developed. The catalyst loaded KNO3 of 35wt.% on Al2O3, after being calcined at 773K for 5h, it was found to be the optimum catalyst, which can give the highest basicity and the best catalytic activity for this reaction. The effects of various reaction variables such as the catalyst loading, oil to methanol ratio, reaction time and temperature on the conversion of soybean oil were investigated. The catalysts were characterized by means of XRD, IR and Hammett titration method. The results indicated that K2O derived from KNO3 at high temperature and that the Al–O–K groups were, probably, the main reasons for the catalytic activity towards the reaction. The catalyst activity was correlated closely with its basicity as determined by the Hammett method. [Copyright &y& Elsevier]