Esterification of Fusel Oil Using Reactive Distillation. Part II: Process Alternatives

In this work, we have studied the potential of reactive distillation for the valorization of fusel oil, i.e., a mixture of alcohols obtained as a distillery waste. It is proposed to react these alcohols in the mixture with acetic acid and separate the esters in pure form. Experiments are performed in a laboratory scale reactive distillation column, and a simulation model is validated. Different process alternatives exist, and we have compared them based on the total energy consumption as the criterion. The potentially cost-effective alternatives are identified. It is shown that reactive distillation, which is a proven intensification strategy for esterification of individual alcohols, can be a promising option for simultaneous esterification of mixture of alcohols, as well

Esterification of lactic acid with n-butanol by reactive distillation

Esterification of lactic acid with n-butanol may be performed to synthesize n-butyl lactate or to recover lactic acid from its aqueous solution. In the present work, the reaction is performed in the presence of cation-exchange resins as a catalyst. Kinetic parameters like activation energy and the rate constants are estimated using the pseudohomogeneous model. The applicability of reactive distillation for this reaction is evaluated through experiments using batch and continuous reactive distillation techniques. An equilibrium stage model is formulated, and simulation results are compared with the experimental results. Further, the effects of operating parameters like feed mole ratio, catalyst loading, and boilup rate are evaluated on the conversion of lactic acid in batch reactive distillation. Experimental results of continuous reactive distillation are compared with the simulation results observed using the Aspen plus process simulator. Effects of operating variables were studied with the help of the experimentally validated model. A continuous reactive distillation process for the recovery of lactic acid is proposed

Esterification of fusel oil using reactive distillation - Part I: Reaction kinetics

Fusel oil is a mixture of C2-C5 alcohols such as ethanol, n-propanol, iso-butanol and iso-amyl alcohol. It is expected that reactive distillation (RD), which is a proven intensification strategy for esterification of individual alcohols can also be a promising option for simultaneous esterification of all the alcohols in fusel oil. To evaluate its feasibility and design a unit on large scale, kinetic and phase equilibrium models are necessary. In this work, we experimentally investigate reaction kinetics for all the esterification and trans-esterification reactions of the different constituents of fusel oil with acetic acid. The reactions are performed in the presence of cation exchange resin, Amberlyst-15, in a batch reactor over a wide range of parameters such as temperature, mole ratio and catalyst loading. A unified Langmuir-Hinshelwood-Hougen-Watson (LHHW) model is proposed for the reacting system consisting of all the alcohols and the experimental data is used to estimate the model parameters. The predictions are in line with the experimental data for individual alcohols as well as their mixtures. A feasible process based on reactive distillation is simulated in ASPEN PLUS using the kinetics developed in this work. (C) 2012 Elsevier B.V. All rights reserved

Nonlinear dynamic effects in reactive distillation for synthesis of TAME

The liquid phase synthesis of octane-enhancing ethers like methyl tert-butyl ether (MTBE) or tert-amyl methyl ether (TAME) can be advantageously performed in a reactive distillation (RD) processes with ion-exchange resin catalyst. In the present paper, a case study for dynamic simulation of a RD process for the production of TAME is presented. Nonlinear dynamic effects such as oscillations, multiple steady states, and internal state multiplicity have been observed under certain conditions. Feed condition and Damkohler number are the important parameters that have influence on the existence of these effects. The presence of these effects has been confirmed through independent bifurcation analysis. The influence of various modeling parameters, reaction kinetics, and phase equilibrium models on this observation is studied

Direct Biomass Fuel Micro-Solid Oxide Fuel Cell

Direct biomass fuel were tested as fuels for operating micro- solid oxide fuel cell. In this study two types of biomass fuels were used viz., Biomethane and rice husk based syngas. Species present in these fuels were analyzed using gas chromatography. It showed that biomethane is composed of N-2 and CH4 whereas syngas comprised of CO2, H-2, N-2, CH4 and CO. During the performance study of the fuel cell, it was observed that syngas when used as fuel operated the cell at lower power density than that of biomethane. Thus an optimal combination of fuel and temperature can serve as a best power source for portable applications

Esterification of Butyl Cellosolve with Acetic Acid using Ion Exchange Resin in Fixed Bed Chromatographic Reactors

Chromatographic reactor is an attractive mode of operation that combines chemical reaction and product separation in the same unit. In this work, esterification of butyl cellosolve with acetic acid using cation exchange resin Amberlyst-15 is investigated in a chromatographic reactor. The study involves determining the appropriate kinetic model for the reaction by performing experiments at different temperatures, mole ratios of the reactants, catalyst loadings and stirring speeds. Characterization of the adsorption capacity of the resin for different components involved in the reaction is performed through adsorption experiments for the non-reactive binaries. The combined separation-reaction process is experimentally investigated using a fixed bed chromatographic column. A mathematical model is developed and the experimental data is compared with the model predictions. It is shown that the experimental and predicted data closely follow each other and that the high conversion can be obtained with a relatively high purity of the product

Aldol condensation of acetone with reactive distillation using water as a selectivity enhancer

Aldol condensation of acetone in the presence of acid catalyst gives diacetone alcohol (DAA) as an intermediate product, which further dehydrates to give mesityl oxide (MO). By using reactive distillation (RD), one can improve selectivity toward DAA, by continuously removing it from the reactive zone and thereby suppressing the dehydration reaction. The presence of water in the reaction mixture has a predominant effect on the intrinsic reaction rates of the individual reactions. This rate-inhibiting effect of water can be advantageously used to improve the selectivity toward the desired intermediate products. The present study, through experiments and simulation, shows that introduction of water in RD can further increase the selectivity toward DAA. Batch kinetics of the reaction in the presence of water is studied, and a suitable kinetic expression is proposed. Further, the batch and continuous reactive distillation experiments are performed to assess the feasibility. The experimental results are explained with the help of an equilibrium-stage model, and the operating parameters for the desired performance are suggested based on the validated model

Feasibility of Reactive Distillation for Fischer-Tropsch Synthesis. 3.

Reactive distillation (RD), a proven reactive separation method that can enhance yields and improve product selectivity in multiple reactant/product systems, was shown to be feasible for FTS in our earlier papers using a simplified kinetics [Srinivas et al. Feasibility of Reactive Distillation for Fischer-Tropsch Synthesis. Ind. Eng. Chem. Res. 2008, 48, 889-899; DOI 10.1021/ie071094p] as well as a detailed kinetics [Srinivas et al. Feasibility of Reactive Distillation for Fischer-Tropsch Synthesis. 2. Ind. Eng. Chem. Res. 2009; DOI 10.1021/ie801887m]. In-built thermodynamic procedures of Aspen Plus, along with a detailed kinetic model that predicts product distribution, were used in performing the simulations. In this paper, we present detailed parametric studies like effect of reflux ratio, H(2)/CO feed ratio, number of nonreactive stages, etc. Conversion, yield, olefin-to-paraffin ratio and product distribution are the parameters used for comparison among the different cases studied. Within RD mode for FTS, some of the alternate column configurations like those with a side-heat removal and a side-draw, a hybrid column with reactive and nonreactive stages, are also explored and investigated

Selectivity engineering with reactive distillation : attainable region for complex reactions

Reactive Distillation (RD) is by now a well established operation that combines reaction and distillation in a single unit to offer enhancement in the overall performance of the process. It leads to enhancement in conversion for reversible reactions and selectivity or yield improvement in the case of multiple reaction schemes. The main underlying principle in application of RD for selectivity engineering is to facilitate the separation of selected components and favorably manipulate the composition profiles in the reactive zone to expedite the desired reaction. In this work, a geometric approach of attainable region (AR), which is already developed for conventional reactor network, is extended further to include representative RD configurations. A model reaction with Van de Vusse scheme (A -> B -> C and 2A -> D) was studied and an algorithm is developed to obtain the attainable reaction for the given kinetics, feed composition and relative volatilities. The AR should be convex with newly defined RD composition vectors on the boundaries should always point inward. The RD vectors emphasize on the need of RD model networking to enlarge the set of attainable compositions until no further enlargement is seen. The results obtained through the algorithm developed above are verified with independent simulation for maximization of selectivity. In almost all different cases of kinetic regime and relative volatilities, RD models perform better than conventional reactors

Feasibility of Reactive Distillation for Fischer-Tropsch Synthesis. 2

The search for alternative sources of transportation fuels and energy security have revived an interest in the Fischer-Tropsch Synthesis (FTS) technology. Over the years, the main driver in FT reactor development has moved from the exothermic heat removal to the product distribution and selectivity. Reactive distillation (RD), a proven reactive separation method that can enhance yields and improve product selectivity in multiple reactant/product systems, was shown to be feasible for FTS in our earlier paper using a simplified kinetics [Srinivas, et al. Feasibility of Reactive distillation for Fischer-Tropsch Synthesis. Ind. Eng. Chem. Res. 2008, 48, 889-899]. This paper looks at the feasibility using a detailed kinetics incorporating olefin readsorption. In-built thermodynamic procedures of Aspen Plus, along with a detailed kinetic model that predicts product distribution, were used in performing the simulations. Some insight is given on the thermodynamics and kinetics used in performing the simulations. Conversion, yield, olefin-to-paraffin ratio, and product distribution are the parameters used for comparison among the different reactor types. Simulation results of the conventional reactors are compared with RD and it is seen that the performance of RD is at par or better than the conventional reactors