Looking back at the literature for enzymatic biodiesel, it is evident that the research has been focused on using immobilized lipase to enable re‐use of the enzyme due to price constraints on lipases used for catalyzing the transesterification process. The use of liquid formulations of lipase for biodiesel has recently been implemented in the industry. Technology for using liquid formulated lipases for enzymatic biodiesel production is new and, since enzyme prices have been reduced, it is now possible to simplify the process considerably and apply it for very low‐quality oils. In this paper, the use of liquid lipase formulations for enzymatic biodiesel will be described along with a general proposal for an industrial‐scale enzymatic biodiesel process with >95 % yield.
Enzymatic production of biodiesel has been the subject of intensive research over the last 5-10 years. When comparing the economy of enzymatic and chemical produced biodiesel important factors include yield, flexibility in feedstock, value of by-products, recovery costs for alcohol as well as the cost of enzyme, enzyme lifetime, reaction time are important factors. By 2009 large-scale enzymatic biodiesel was considered to be cost effective [1]. Since then development work has further improved the technology which is now ready for the market. We have developed a full enzymatic two-step process for converting oils to biodiesel, and a pretreatment unit which can be installed in an existing chemical biodiesel plant to enable it to process high free fatty acid feedstocks.
The alkaline process for making biodiesel (fatty acid methyl esters, or FAME) is highly efficient at the transesterification of glycerides. However, its performance is poor when it comes to using oil that contain significant amounts of free fatty acids (FFA). The traditional approach to such feedstocks is to employ acid catalysis, which is slow and requires a large excess of methanol, or to evaporate FFA and convert that in a separate process. An attractive option would be to convert the FFA in oil feedstocks to FAME, before introducing it into the alkaline process. The high selectivity of enzyme catalysis makes it a suitable basis for such a pretreatment process. In this work, we present a characterization of the pretreatment of high-FFA rapeseed oil using immobilized Candida antarctica lipase B (Novozym 435), focused on the impact of initial FFA and methanol concentration. Based on experimental results, we have identified limitations for the process in terms of FFA concentration in the feedstock and make suggestions for process operation. It was found that, using 5% catalyst and 4% methanol at 35°C, the FFA concentration could be reduced to 0.5% within an hour for feedstock containing up to 15% FFA. Further, the reaction was observed to be under kinetic control, in that the biocatalyst converts FFA (and FAME) at a much higher rate than glyceride substrates. There is thus, both a minimum and a maximum reaction time for the process to achieve the desired concentration of FFA. Finally, an assessment of process stability in a continuous packed bed system indicates that as much as 15 m(3) oil could potentially be pretreated by 1 kg of biocatalyst at the given process conditions.
Enzymatic biodiesel production has been at the forefront of biofuels research in recent decades because of the significant environmental advantages it offers, while having the potential to be as effective as conventional chemically catalyzed biodiesel production. However, the higher capital cost, longer reaction time, and sensitivity of enzyme processes have restricted their widespread industrial adoption so far. It is also posited that the lack of research to bring the biodiesel product into final specification has scuppered industrial confidence in the viability of the enzymatic process. Furthermore, the vast majority of literature has focused on the development of immobilized enzyme processes, which seem too costly (and risky) to be used industrially. There has been little focus on liquid lipase formulations such as the Eversa Transform 2.0, which is in fact already used commercially for triglyceride transesterification. It is the objective of this review to highlight new research that focuses on bringing enzymatically produced biodiesel into specification via a liquid lipase polishing process, and the process considerations that come with it. ©
Estolides are fatty acid polyesters with applications in both industry and consumer products. Recently, reports have emerged detailing lipase-catalyzed synthesis of estolides from free hydroxy fatty acids. In this paper, we describe a simple alternative enzymatic process, in which castor oil is directly converted to an estolide mixture by Candida antarctica lipase A (CALA) catalyzed transesterification. The reaction mixture is analyzed by NMR to determine the estolide number (EN) and MALDI MS to identify individual components, in addition to titration to determine the acid value (AV). Estolide trimers and tetramers (EN 2–3) were formed over 24 h in a system with 2:1 (v/v) castor oil–water. Further, utilizing different lipase specificities, addition of Thermomyces lanuginosus lipase (TLL), allowed the CALA product mixture to be cleaned up by hydrolyzing attached glycerol. In addition, a three-enzyme process is suggested, in which a simple alcohol is added and Candida antarctica lipase B (CALB) is used to esterify carboxylic acids to lower AV.
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