Florin Omota

Fatty acid esterification by reactive distillation. Part 2: kinetics-based design for sulphated zirconia catalysts

Abstract In a previous study on the basis of reaction equilibrium, it was demonstrated that the synthesis of fatty acids esters of heavy alcohols by catalytic reactive distillation (RD) is basically feasible. Presently, the analysis is expanded to the kinetics-based design applied to the synthesis of 2-ethylhexyl dodecanoate. Experimental data for a super-acidic sulphated zirconia catalyst are employed. It is shown that this catalyst is highly selective even for the high alcohol/acid ratios as prevail in a RD column. To avoid catalyst deactivation, liquid–liquid segregation into an organic and an aqueous phase must be prevented, and operating temperatures beyond 373 K must be chosen. A kinetic model based on liquid activities is proposed, with parameters determined from both kinetic and equilibrium measurements. A typical column design has 13 reactive stages with a catalyst loading of 170 kg m −3 , temperature profile of 400– 440 K , and a space velocity of 0.022 kmol kg cat −1 h −1 for 99.9% purity product ester. A modified Damkohler number is proposed.

Innovative process for fatty acid esters by dual reactive distillation

Catalytic reactive distillation offers new opportunities for manufacturing fatty acid esters, involved both in biodiesel and specialty chemicals. A key problem is the effective water removal in view of protecting the solid catalyst and avoiding costly recovery of the alcohol excess. This work proposes a novel approach based on dual esterification of fatty acid with light and heavy alcohols, namely methanol and 2-ethylhexanol. These two complementary reactants have an equivalent reactive function but synergistic thermodynamic features. The setup behaves rather as reactive absorption combined with reactive azeotropic distillation with heavy alcohol as co-reactant and water-separation agent. Another element of originality is the control of the inventory of alcohols by fixing the reflux of heavy alcohol and the light alcohol column inflow. This strategy allows achieving both stoichiometric reactant feed rate and large flexibility in ester production. The distillation column for recovering light alcohol from water is not longer necessary. The result is a compact, efficient and easy-to-control multi-product reactive setup.

Fatty acid esterification by reactive distillation. Part 1: equilibrium-based design

Abstract Esters of fatty acids are currently produced in batch processes. In this study we present an innovative process based on reactive distillation (RD). The synthesis of a several fatty esters is possible in the same RD set-up, making possible the development of a continuous multipurpose process. Conceptual design is presented as a systematic methodology based on thermodynamic analysis combined with computer simulation. This approach sets also targets for limited experimental work. The methodology is illustrated by the esterification of lauric acid with 2-ethylhexanol and methanol, the heaviest and lightest alcohol in the C 1 –C 8 series. The first part presents the design of a RD set-up based on chemical equilibrium. Both reactions can be accommodated in the same hardware, but with different operation procedures. The alternative with alcohol reflux is suitable for heavy alcohols that form heterogeneous azeotropes with water. Another alternative with acid reflux can accommodate both light and heavy alcohols, and may be seen as a generic process for fatty acid esterification.

Process for fatty acid methyl esters by dual reactive distillation

Abstract Fatty acid methyl esters (FAME) , valuable oleo-chemicals and main constituent of biodiesel, can be manufactured in a continuous process based on reactive distillation and solid catalyst. A central problem is the effective water removal. In this work we propose a novel approach, namely dual esterification with a mixture of methanol and long-chain alcohol, as 2-ethylhexanol, which plays the role of reactant and mass separation agent. The key benefits are multi-functional reactive distillation device, high flexibility in operation and reduced equipment costs due to the highly integrated design.

Design of reactive distillation process for fatty acid esterification

Publisher Summary Esters of fatty acids are produced in batch reactors. This chapter presents an innovative continuous process based on reactive distillation that can be used as a multipurpose configuration allowing the synthesis of a variety of fatty esters. The approach consists of chemical and phase equilibrium analysis to identify the feasible design region and computer simulation to generate process alternatives. Results are presented for the esterification of lauric acid with methanol and 2-ethylhexanol, the lightest and the heaviest in the C 1 –C 8 alcohol series. Two process alternatives can be accommodated in the same hardware, but with different operation procedures: one with alcohol reflux and other with acid reflux. The first is feasible for heavy alcohols, forming heterogeneous azeotrope with water. The second is suited for both light and heavy alcohols and may be seen as a generic esterification process of fatty acids. Kinetic measurements are tested by simulation method. A laboratory setup is currently builtup to prove the feasibility of this new process.

Entrainer-Assisted Reactive Distillation. Application to Process Synthesis of Fatty Acids

Abstract A new approach in designing reactive distillation processes is presented: the use of an entrainer. This can help to overcome limitations due to distillation boundaries, and in the same time to increase the degrees of freedom in design. As example the catalytic esterification of fatty acids with 1-propanol is studied. The entrainer enhances the water removal and increases the amount of alcohol recycled inside the reaction space. A major benefit is a significant reduction of the amount of catalyst compared with the situation without entrainer.

Integration of particle to bubble adhesion model in design and scale-up of slurry bubble columns

Abstract In slurry bubble column reactors, catalyst particles may adhere to gas bubbles. Thus, mass transfer limited reactions can be significantly improved either by increasing G-L mass transfer coefficient k L or specific surface area a . The scope of this work is to study the influence of model parameters on coalescence and G-L mass transfer, in order to develop new rules for design and scale-up of slurry bubble columns. A novel model describing adhesion of particles to gas bubbles was developed. The effects of particle size, hydrophobicity and porosity on particle-to-bubble adhesion and bubble coalescence were determined experimentally in a bubble pick-up/coalescence cell. Total gas hold-up, bubble rise velocities and size distribution were measured in a 2-D column. Hydrogenation of methyl acrylate catalyzed by Pd/SiO 2 catalysts was performed in a stirred reactor. Hydrophobic catalyst particles adhering at G-L interface slightly increases bubble coalescence rate, but leads to a mass transfer rate up to 450% higher. The particles adhere preferentially to small bubbles increasing G-L mass transfer while higher coalescence rate of large bubbles explains a decrease in gas hold-up.