Influence of feedstock source on the biocatalyst stability and reactor performance in continuous biodiesel production

Solvent-Free Enzymatic Synthesis of Dietary Triacylglycerols from Cottonseed Oil in a Fluidized Bed Reactor

The synthesis of structured lipids with nutraceutical applications, such as medium-long-medium (MLM) triacylglycerols, via modification of oils and fats represents a challenge for the food industry. This study aimed to synthesize MLM-type dietary triacylglycerols by enzymatic acidolysis of cottonseed oil and capric acid (C10) catalyzed by Lipozyme RM IM (lipase from Rhizomucor miehei) in a fluidized bed reactor (FBR). After chemical characterization of the feedstock and hydrodynamic characterization of the reactor, a 2² central composite rotatable design was used to optimize capric acid incorporation. The independent variables were cycle number (20-70) and cottonseed oil/capric acid molar ratio (1:2-1:4). The temperature was set at 45 °C. The best conditions, namely a 1:4 oil/acid molar ratio and 80 cycles (17.34 h), provided a degree of incorporation of about 40 mol%, as shown by compositional analysis of the modified oil. Lipozyme RM IM showed good operational stability (k_d = 2.72 × 10^-4 h^-1, t_1/2 = 2545.78 h), confirming the good reuse capacity of the enzyme in the acidolysis of cottonseed oil with capric acid. It is concluded that an FBR configuration is a promising alternative for the enzymatic synthesis of MLM triacylglycerols.

Application of Tubular Reactor Technologies for the Acceleration of Biodiesel Production

The need to arrest the continued environmental contamination and degradation associated with the consumption of fossil-based fuels has continued to serve as an impetus for the increased utilization of renewable fuels. The demand for biodiesel has continued to escalate in the past few decades due to urbanization, industrialization, and stringent government policies in favor of renewable fuels for diverse applications. One of the strategies for ensuring the intensification, commercialization, and increased utilization of biodiesel is the adaptation of reactor technologies, especially tubular reactors. The current study reviewed the deployment of different types and configurations of tubular reactors for the acceleration of biodiesel production. The feedstocks, catalysts, conversion techniques, and modes of biodiesel conversion by reactor technologies are highlighted. The peculiarities, applications, merits, drawbacks, and instances of biodiesel synthesis through a packed bed, fluidized bed, trickle bed, oscillatory flow, and micro-channel tubular reactor technologies are discussed to facilitate a better comprehension of the mechanisms behind the technology. Indeed, the deployment of the transesterification technique in tubular reactor technologies will ensure the ecofriendly, low-cost, and large-scale production of biodiesel, a high product yield, and will generate high-quality biodiesel. The outcome of this study will enrich scholarship and stimulate a renewed interest in the application of tubular reactors for large-scale biodiesel production among biodiesel refiners and other stakeholders. Going forward, the use of innovative technologies such as robotics, machine learning, smart metering, artificial intelligent, and other modeling tools should be deployed to monitor reactor technologies for biodiesel production.

Process intensification using immobilized enzymes for the development of white biotechnology

Process intensification of biocatalysed reactions using different techniques such as microwaves, ultrasound, hydrodynamic cavitation, ionic liquids, microreactors and flow chemistry in various industries is critically analysed and future directions provided.

Synthesis of 2-ethylhexyl oleate catalyzed by Candida antarctica lipase immobilized on a magnetic polymer support in continuous flow

This study investigated the synthesis of 2-ethylhexyl oleate catalyzed by Candida antarctica lipase immobilized on magnetic poly(styrene-co-divinylbenzene) particles in a continuous packed-bed bioreactor. Runs were carried out in a solvent-free system at 50 °C. The performance of the reactor was evaluated for substrates composed by oleic acid and 2-ethylhexanol at five molar ratios (1:4-4:1), determining its operation limits in terms of substrate flow rate. The system performance was quantified for three different flow rates corresponding to space-time between 3 and 12 h. For each condition, the influence of the space-time in the ester formation, esterification yield and productivity was determined. The molar ratio of acid-to-alcohol interfered, in a remarkable way, in the formation of 2-ethylhexyl oleate and the best performance was attained for substrate at equimolar ratio running at 12 h space-time. Under this condition, average 2-ethylhexyl oleate concentration was 471.65 ± 2.98 g L^-1 which corresponded to ester productivity of 23.16 ± 0.49 mmol g^-1 L^-1 h^-1. This strategy also gave high biocatalyst operational stability, revealing a half-life time of 2063 h. A model based on the ping-pong Bi-Bi mechanism was developed to describe the kinetics of the esterification reaction and validated using experimental data. The goodness of fit of the model was satisfactory (R² = 0.9310-0.9952).

Enzymatic synthesis of ethyl esters from waste oil using mixtures of lipases in a plug-flow packed-bed continuous reactor

This work describes the continuous synthesis of ethyl esters via enzymatic catalysis on a packed-bed continuous reactor, using mixtures of immobilized lipases (combi-lipases) of Candida antarctica (CALB), Thermomyces lanuginosus (TLL), and Rhizomucor miehei (RML). The influence of the addition of glass beads to the reactor bed, evaluation of the use of different solvents, and flow rate on reaction conditions was studied. All experiments were conducted using the best combination of lipases according to the fatty acid composition of the waste oil (combi-lipase composition: 40% of TLL, 35% of CALB, and 25% of RML) and soybean oil (combi-lipase composition: 22.5% of TLL, 50% of CALB, and 27.5% of RML). The best general reaction conditions were found to be using tert-butanol as solvent, and the flow rate of 0.08 mL min^-1 . The combi-lipase reactors operating at steady state for over 30 days (720 h), kept conversion yields of ∼50%, with average productivity of 1.94 g_{ethyl esters}gsubstrate-1 h^-1 , regardless of the type of oil in use. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:952-959, 2018.