TY - BOOK

T1 - Process Technology for Immobilized Lipasecatalyzed Reactions

A1 - Xu,Yuan

AU - Xu,Yuan

A2 - Woodley,John

A2 - Nordblad,Mathias

ED - Woodley,John

ED - Nordblad,Mathias

PB - DTU Chemical Engineering

PY - 2012

Y1 - 2012

N2 - Biocatalysis has attracted significant attention recently, mainly due to its high selectivity and <br/>potential benefits for sustainability. Applications can be found in biorefineries, turning <br/>biomass into energy and chemicals, and also for products in the food and pharmaceutical <br/>industries. However, most applications remain in the production of high-value fine chemicals, <br/>primarily because of the expense of introducing new technology. In particular lipasecatalyzed <br/>synthesis has already achieved efficient operations for high-value products and <br/>more interesting now is to establish opportunities for low-value products. In order to guide <br/>the industrial implementation of immobilized-lipase catalyzed reactions, especially for highvolume <br/>low-value products, a methodological framework for dealing with the technical and <br/>scientific challenges and establishing an efficient process via targeted scale-down <br/>experimental work is described in this thesis. The methodology uses economic targets to test <br/>options characterized via a set of tools. <br/>In order to validate the methodology, two processes based on immobilized lipase-catalysis <br/>have been studied: transesterification and esterification of vegetable oils for the production of <br/>biodiesel. The two processes are focused on the conversion of the two main components of <br/>vegetable oil materials, glyceride esters and free fatty acids respectively, into fatty acid alkyl <br/>esters. Although biodiesel is conventionally prepared via chemical-catalyzed <br/>transesterification of vegetable oils with methanol to produce fatty acid methyl esters <br/>(FAME), this work has been focused on the production of fatty acid ethyl esters (FAEE) with <br/>bioethanol due to the expected improved sustainability of this type of biodiesel. <br/>A key reaction characteristic of the immobilized lipase-catalyzed transesterification is that it <br/>is multi-phasic system. The by-product glycerol can potentially impose inhibitory effects on <br/>immobilized lipases and likewise the un-dissolved ethanol can inhibit the lipase. The options <br/>for addressing these issues can be used as the basis for selecting the biocatalyst and the <br/>reactor (e.g. a hydrophobic carrier for the immobilized lipase and the capabilities to provide <br/>sufficient mixing as well as stepwise/continuous feeding of ethanol to the reactor). <br/>An STR is efficient for batch operation while a PBR is efficient for a continuous production. <br/>An STR can more easily provide sufficient external mass transfer for a reaction, but will lead <br/>to more mechanical damage of the biocatalyst particles, than a PBR. A reactor combination <br/>of CSTR with PBR can couple the advantages of both, delivering an efficient continuous <br/>process. <br/>The second case study (esterification) shares some similar process characteristics to the first <br/>case (e.g. the multi-phasic nature). However, instead of glycerol, water shows a great impact <br/>on the extent of reaction. The removal of water should therefore be feasible during the <br/>operation of the reactor, either intermittently or preferably in situ. Highly anhydrous reaction <br/>conditions and the smaller substrates for this reaction place particular requirements on the <br/>lipase. <br/>In order to validate the established processes at a larger scale, both lipase-catalyzed <br/>transesterification and esterification developed in the lab-scale STRs have been carried out in <br/>pilot-scale STRs. Results in both scale STRs correlate well with respect to the biocatalyst <br/>performance and mechanical stability. <br/>Once the technical and scientific challenges of the process have been addressed, it is of <br/>course important to evaluate its economic and environmental feasibility. To that end, process <br/>evaluation has been performed for six processes composed of transesterification and product <br/>purification for making ‘in-spec’ biodiesel and the conventional chemical process is taken as <br/>a bench mark for comparison. The optimal process is a process composed of lipase-catalyzed <br/>transesterification with ‘in-spec’ biodiesel product as output with less feedstock input and <br/>waste production and much saved energy from the absence of product purification.

AB - Biocatalysis has attracted significant attention recently, mainly due to its high selectivity and <br/>potential benefits for sustainability. Applications can be found in biorefineries, turning <br/>biomass into energy and chemicals, and also for products in the food and pharmaceutical <br/>industries. However, most applications remain in the production of high-value fine chemicals, <br/>primarily because of the expense of introducing new technology. In particular lipasecatalyzed <br/>synthesis has already achieved efficient operations for high-value products and <br/>more interesting now is to establish opportunities for low-value products. In order to guide <br/>the industrial implementation of immobilized-lipase catalyzed reactions, especially for highvolume <br/>low-value products, a methodological framework for dealing with the technical and <br/>scientific challenges and establishing an efficient process via targeted scale-down <br/>experimental work is described in this thesis. The methodology uses economic targets to test <br/>options characterized via a set of tools. <br/>In order to validate the methodology, two processes based on immobilized lipase-catalysis <br/>have been studied: transesterification and esterification of vegetable oils for the production of <br/>biodiesel. The two processes are focused on the conversion of the two main components of <br/>vegetable oil materials, glyceride esters and free fatty acids respectively, into fatty acid alkyl <br/>esters. Although biodiesel is conventionally prepared via chemical-catalyzed <br/>transesterification of vegetable oils with methanol to produce fatty acid methyl esters <br/>(FAME), this work has been focused on the production of fatty acid ethyl esters (FAEE) with <br/>bioethanol due to the expected improved sustainability of this type of biodiesel. <br/>A key reaction characteristic of the immobilized lipase-catalyzed transesterification is that it <br/>is multi-phasic system. The by-product glycerol can potentially impose inhibitory effects on <br/>immobilized lipases and likewise the un-dissolved ethanol can inhibit the lipase. The options <br/>for addressing these issues can be used as the basis for selecting the biocatalyst and the <br/>reactor (e.g. a hydrophobic carrier for the immobilized lipase and the capabilities to provide <br/>sufficient mixing as well as stepwise/continuous feeding of ethanol to the reactor). <br/>An STR is efficient for batch operation while a PBR is efficient for a continuous production. <br/>An STR can more easily provide sufficient external mass transfer for a reaction, but will lead <br/>to more mechanical damage of the biocatalyst particles, than a PBR. A reactor combination <br/>of CSTR with PBR can couple the advantages of both, delivering an efficient continuous <br/>process. <br/>The second case study (esterification) shares some similar process characteristics to the first <br/>case (e.g. the multi-phasic nature). However, instead of glycerol, water shows a great impact <br/>on the extent of reaction. The removal of water should therefore be feasible during the <br/>operation of the reactor, either intermittently or preferably in situ. Highly anhydrous reaction <br/>conditions and the smaller substrates for this reaction place particular requirements on the <br/>lipase. <br/>In order to validate the established processes at a larger scale, both lipase-catalyzed <br/>transesterification and esterification developed in the lab-scale STRs have been carried out in <br/>pilot-scale STRs. Results in both scale STRs correlate well with respect to the biocatalyst <br/>performance and mechanical stability. <br/>Once the technical and scientific challenges of the process have been addressed, it is of <br/>course important to evaluate its economic and environmental feasibility. To that end, process <br/>evaluation has been performed for six processes composed of transesterification and product <br/>purification for making ‘in-spec’ biodiesel and the conventional chemical process is taken as <br/>a bench mark for comparison. The optimal process is a process composed of lipase-catalyzed <br/>transesterification with ‘in-spec’ biodiesel product as output with less feedstock input and <br/>waste production and much saved energy from the absence of product purification.

BT - Process Technology for Immobilized Lipasecatalyzed Reactions

ER -