► In this paper we review the technologies related to biodiesel production. ► 4 Primary approaches reviewed are direct use and blending of oils, micro-emulsions, pyrolysis and transesterification ...method. ► Both advantages and disadvantages of the different biodiesel production methods are also discussed. ► The most common technology of biodiesel production is transesterification of oils. ► Selection of a transesterification method depends on the amount of FFA and water content of the feedstock.
Despite the high energy demand in the industrialized world and the pollution problems caused by widespread use of fossil fuels, the need for developing renewable energy sources with less environmental impacts are increasing. Biodiesel production is undergoing rapid and extensive technological reforms in industries and academia. The major obstacle in production and biodiesel commercialization path is production cost. Thus, in previous years numerous studies on the use of technologies and different methods to evaluate optimal conditions of biodiesel production technically and economically have been carried out. In this paper, a comparative review of the current technological methods so far used to produce biodiesel has been investigated. Four primary approaches to make biodiesel are direct use and blending of vegetable oils, micro-emulsions, thermal cracking (pyrolysis) and transesterification. Transesterification reaction, the most common method in the production of biodiesel, is emphasized in this review. The two types of transestrification process; catalytic and non-catalytic are discussed at length in the paper. Both advantages and disadvantages of the different biodiesel production methods are also discussed.
Anionic hybrid copolymerization of vinyl and cyclic monomers provides a powerful strategy to synthesize heteropolymers. Yet, there are some open questions regarding its mechanism and the structure of ...the resulted polymer. We reported that the copolymer (Poly(MMA-co-CL)) of methyl methacrylate (MMA) and ε-caprolactone (CL) via such copolymerization was random. However, a recent study proposed that the copolymer might be simple graft one with poly(methyl methacrylate) (PMMA) as the main chain and poly(ε-caprolactone) (PCL) as the graft chain. In this study, we synthesized a model graft copolymer (PMMA-g-PCL) by using a combination of reversible complexation-mediated polymerization and ring-opening polymerization, and made comparison with Poly(MMA-co-CL) in their properties and hydrolysis. Differential scanning calorimeter (DSC) measurements show that the graft copolymer PMMA-g-PCL possesses two glass transitions and a melt peak. In contrast, Poly(MMA-co-CL) exhibits only one glass transition without a melt peak because it is amorphous, clearly indicating that it is random. Proton nuclear magnetic resonance (1H NMR) measurements reveal that the hydrolysis of PMMA-g-PCL yields only PMMA oligomers. However, the hydrolyzed products of Poly(MMA-co-CL) consist of MMA and CL units. The facts further indicate that the copolymer Poly(MMA-co-CL) is random. Considering that the transesterification reactions are unavoidable in the anionic hybrid copolymerization, the copolymer should consist of random main chain and random branches.
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•The present study demonstrates that anionic hybrid copolymerization of MMA and CL generally yields random copolymer but not graft copolymer.•Transesterification is not the essential step in the anionic hybrid copolymerization, but it can cause branching of the copolymer.•The hybrid copolymer of MMA and CL consists random main chain and random branches.
Biobased Transesterification Vitrimers Kumar, Ashwani; Connal, Luke A.
Macromolecular rapid communications,
April 2023, Letnik:
44, Številka:
7
Journal Article
Recenzirano
Odprti dostop
The rapid increase in the use of plastics and the related sustainability issues, including the depletion of global petroleum reserves, have rightly sparked interest in the use of biobased polymer ...feedstocks. Thermosets cannot be remolded, processed, or recycled, and hence cannot be reused because of their permanent molecular architecture. Vitrimers have emerged as a novel polymer family capable of bridging the difference between thermoplastic and thermosets. Vitrimers enable unique recycling strategies, however, it is still important to understand where the raw material feedstocks originate from. Transesterification vitrimers derived from renewable resources are a massive opportunity, however, limited research has been conducted in this specific family of vitrimers. This review article provides a comprehensive overview of transesterification vitrimers produced from biobased monomers. The focus is on the biomass structural suitability with dynamic covalent chemistry, as well as the viability of the synthetic methods.
Biobased vitrimers can provide a sustainable approach to replace fossil fuel‐derived thermoset plastics. This review presents a comprehensive overview of the design, synthesis, and dynamic properties of biobased vitrimeric materials with a focus on the transesterification bond exchange process. Future plans and difficulties for the development of biobased transesterification vitrimers with excellent performance are also presented.
The nature of alcohol and alcohol to oil molar ratio plays an important role on the method of biodiesel production. As a result, this paper examined different alcohols commonly used for the ...production of biodiesel fuel with more emphasis on methanol and ethanol. Further the different alcohol to oil molar ratios used for the production of biodiesel have been extensively discussed and reported. Also the effects of alcohol to molar ratios on biodiesel refining process and its physicochemical properties were investigated.
•A comprehensive overview of recent progress in enzymatic biodiesel production.•Critical assessment of merits and demerits of enzymatic biodiesel process.•Economic considerations and large scale ...developments in enzymatic biodiesel.•Current trends and future directions for enzymatic biodiesel R&D.
The chemical-catalyzed transesterification of vegetable oils to biodiesel has been industrially adopted due to its high conversion rates and low production time. However, this process suffers from several inherent drawbacks related to energy-intensive and environmentally unfriendly processing steps such as catalyst and product recovery, and waste water treatment. This has led to the development of the immobilized enzyme catalyzed process for biodiesel production which is characterized by certain environmental and economical advantages over the conventional chemical method. These include room-temperature reaction conditions, elimination of treatment costs associated with recovery of chemical catalysts, enzyme re-use, high substrate specificity, the ability to convert both free fatty acids and triglycerides to biodiesel in one step, lower alcohol to oil ratio, avoidance of side reactions and minimized impurities, easier product separation and recovery; biodegradability and environmental acceptance. This paper provides a comprehensive review of the current state of advancements in the enzymatic transesterification of oils. A thorough analysis of recent biotechnological progress is presented in the context of present technological challenges and future developmental opportunities aimed at bringing the enzyme costs down and improving the overall process economics towards large scale production of enzymatic biodiesel. As the major obstacles that impede industrial production of enzymatic biodiesel is the enzyme cost and conversion efficiency, this topic is addressed in greater detail in the review. A better understanding and control of the underpinning mechanisms of the enzymatic biodiesel process would lead to improved process efficiency and economics. The yield and conversion efficiency of enzymatic catalysis is influenced by a number of factors such as the nature and properties of the enzyme catalyst, enzyme and whole cell immobilization techniques, enzyme pretreatment, biodiesel substrates, acyl acceptors and their step-wise addition, use of solvents, operating conditions of enzymatic catalysis, bioreactor design. The ability of lipase to catalyze the synthesis of alkyl esters from low-cost feedstock with high free fatty acid content such as waste cooking oil, grease and tallow would lower the cost of enzymatic biodiesel. Discovery and engineering of new and robust lipases with high activity, thermostability and resistance to inhibition are needed for the establishment of a cost-effective enzymatic process. Opportunities to create a sustainable and eco-friendly pathway for production of enzymatic biodiesel from renewable resources are discussed.
Photo‐curing 3D printing technology has promoted the advanced manufacturing in various fields, but has exacerbated the environmental crisis by the demand for the chemically cross‐linked thermosetting ...photopolymers. Here, the authors report a generic strategy to develop catalyst‐free dynamic thermosetting photopolymers, based on photopolymerization and transesterification, that can enable users to realize repeatable 3D printing, providing a practical solution to the environmental challenges. That the β‐carbonyl group adjacent to the ester group greatly accelerates the rate of transesterification is demonstrated. The generated resins from the immobilization of the catalyst‐free reversible bonds into the photopolymers leads to a dynamic covalently crosslinked network structure upon UV based 3D printing, which exhibit controllable mechanical properties with elastomeric behaviors to thermadapt shape memory polymers. Furthermore, the resulting network can be reverted into an acrylate‐functioned photopolymer that is suitable for 3D printing again, presenting an on‐demand, repeatedly recyclable thermosetting photopolymer platform for sustainable 3D printing.
Catalyst‐free dynamic thermosetting photopolymers are developed by immobilized the catalyst‐free reversible bonds into the photopolymers, that can enable users to realize repeatable 3D printing. The generated resins demonstrate controllable mechanical properties with elastomeric behaviors to thermadapt shape memory polymers. Furthermore, the resulting network presents an on‐demand, repeatedly recyclable thermosetting photopolymer platform for sustainable 3D printing.
Despite considerable research efforts, lipase catalysis in a fluid milk system with aqueous multi-component mixtures containing multiple microphases, remains challenging. Pickering interfacial ...biocatalysis (PIB) platforms are typically fabricated with organic solvents/lipids and water. Whether a PIB with excellent catalytic performance can be constructed in complex milk mixtures remains unknown. Here, we challenged PIB with skim milk, and a small amount of flaxseed oil, and phytosterols as a model system for transesterification and lipolysis to enhance quality and flavor. The amino-modified mesoporous silica spheres (MSS-N) were employed as an emulsifier and carrier of lipase AYS (AYS@MSS-N). The conversion of phytosterol esters reached 75.5% at 1.5 h and prepared phytosterol ester-fortified milk with a content of 1.0 g/100 mL. The relative conversion rate remained above 70% after 6 cycles. In addition, the fortified milk showed an intensified and favorable effect on sensory traits through volatile flavor composition analysis. The findings provide a versatile alternative for PIB applications in complex environments, i.e., milk, which might inspire a new bioprocess strategy for dairy products.
The ever increase in global energy demand, consumption of depletable fossil fuels, exhaust emissions and global warming, all these led to search about alternative fuels. Biodiesel was produced from ...waste cooking-oil by transesterification process. Blends of waste cooking-oil biodiesel and diesel oil were prepared in volume percentages of 10, 20 and 30% as B10, B20 and B30. Biodiesel blends have ASTM standards of physical and chemical characterization near to diesel fuel. Diesel engine performance and exhaust emissions were studied experimentally for burning waste cooking-oil blend with diesel fuel. This experimental was applied on a diesel engine at different engine loads from zero to full load. Thermal efficiencies for waste cooking-oil biodiesel blends were lower than diesel oil. Specific fuel consumptions of biodieselblends were higher than diesel fuel. Higher exhaust gas temperatures were recorded for biodiesel blends compared to diesel oil. CO2 emissions for waste cooking-oil biodiesel blends were higher than diesel oil. CO, smoke opacity and HC emissions for biodiesel blends were lower than diesel fuel. NOx emissions for biodiesel blends were higher than diesel fuel.
CaO derived from calcined eggshell was doped with Na–K by wet impregnation method and the effect of different Na/K molar ratios was investigated on biodiesel production from canola oil. The catalysts ...were characterized by X-ray Powder Diffraction (XRD), Brunauer–Emmett–Teller (BET), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), and Thermogravimetric (TGA) analyses. FAME yields were determined by Gas Chromatography-Mass Spectrometry (GC-MS). The Na–K/CaO catalyst with Na/K molar ratio of 1 showed the highest FAME yield of 97.6% at optimum reaction conditions. Structural investigation of materials revealed that FAME yield was proportional to the number of basic sites on the surface of catalyst. The optimum reaction conditions were found to be catalyst loading of 3 wt%, methanol to oil molar ratio of 9:1, reaction temperature of 50 °C, and reaction time of 3 h.
•Transesterification of canola oil was carried out over eggshell derived catalysts.•Effect of Na/K molar ratio has been investigated on FAME yield.•The optimum reaction conditions were investigated.•CaO doped with Na/K molar ratio of 1 resulted in highest FAME yield of 97.6%.•Catalysts’ activity is proportional to its’ basicity.
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