Continuous enzymatic biodiesel production from coconut oil in two-stage packed-bed reactor incorporating an extracting column to remove glycerol formed as by-product

Abstract

The transesterification of coconut oil with ethanol catalyzed by Burkholderia cepacia lipase immobilized on polysiloxane-polyvinyl alcohol was performed in a continuous flow. The experimental design consisted of a two-stage packed-bed reactor incorporating a column with cationic resin (Lewatit GF 202) to remove the glycerol formed as by-product and the reactor performance was quantified for three different flow rates corresponding to space-times from 10 to 14 h. The influence of space-time on the ethyl ester (FAEE) concentrations, yields and productivities was determined. The reactor operation was demonstrated for space-time of 14 h attaining FAEE concentrations of 58.5 ± 0.87 wt%, FAEE yields of 97.3 ± 1.9 % and productivities of 41.6 ± 1.0 mgester g medium (-1) h(-1). Biodiesel purified samples showed average kinematic viscosity values of 5.5 ± 0.3 mm(2) s(-1) that meet the criteria established by the American National Standard ASTM (D6751). The immobilized lipase was found to be stable regarding its morphological and catalytic characteristics, showing half-life time (t 1/2) around 1540 h. The continuous packed-bed reactor connected in series with simultaneous glycerol removal has a great potential to attain high level of transesterification yields, raising biodiesel productivity.

Enzyme-Catalyzed Production of Biodiesel as Alternative to Chemical- Catalyzed Processes: Advantages and Constraints

“…In most cases, the optimum methanol/oil molar ratio (MR) corresponds to the stoichiometric value of 3:1, for non-regioselective lipases, or slightly higher values. However, higher molar ratios were used in batch methanolysis catalyzed by Burkholderia cepacia lipase immobilized on modified attapulgite (MR = 6.6:1) [153] or by B. cepacia lipase immobilized on silica-PVA matrix and used in continuous ethanolysis (MR Ethanol/oil = 7) [154]. This can be explained by the high tolerance of B. cepacia lipase to alcohols, namely to methanol [155].…”

“…S-2 yeast lipase [166], the lipase/acyltransferase from Candida parapsilosis [159] and intracellular Cal A and Cal B lipases [83] are examples of non-commercial enzymes tested for biodiesel production. Synthetic resins [82,137,156,158,159,186,187], silica derivatives [154,157,188], modified attapulgite [153] and calcium alginate [83] are examples of carriers used for enzyme immobilization.…”

“…Mainly these bioreactors work with immobilized lipases to increase the productivity and reduce the cost of the biocatalyst per ton of biodiesel and minimizing the problems associated to the scale-up of the process. Most of the studies are batchwise but the implementation in continuous bioreactors is also described with very high operational stability results [154,157,196].…”

Combined Use of a Two-Stage Packed Bed Reactor with a Glycerol Extraction Column for Enzymatic Biodiesel Synthesis from Macaw Palm Oil

“…3,7 Such limitations can be associated either with the reactor's dimensions 13 or to catalyst bed obstruction by accumulation of components from the reaction mixture, which include glycerol, the main byproduct of transesterification reactions. 9,12,14 To overcome such limitations, various factors that affect the design of reactors have been already investigated 7,11,13 and, in this work, attention was particularly given to study of the influence of packed bed reactors with different geometry relations (l/d) on the overall process in order to select the reactor that afforded the higher feedstock conversion into ethyl esters. To reduce the adsorption of polar compounds by the immobilizing support which imposes diffusion limitations and lipase inhibition, the glycerol formed as byproduct was removed by adsorption with the commercial resin Lewatit GF 202.…”

Biological Methods in Biodiesel Production and Their Environmental Impact

“…The continuous bioreactor has some advantages in comparison with batch reactors, such as better control of process parameters, mass transfer, mixing of reagents, energy efficiency, and product separation (fewer unit operations), and better efficiency of the enzyme used (lower amounts of enzyme per volume in the reactor) [62]. Moreover, using the solutions in the bioreactor which enable stepwise addition of alcohols and continuous removal of glycerol, the conversion yield of transesterification can be improved [64,65].…”