Reactive distillation with side draw

We demonstrate the applicability of a new reactive distillation configuration, i.e. reactive distillation with side draw, for certain industrially important reactions. For the reacting systems which involve products with intermediate volatility, a side draw facilitates its in situ removal and enhances either conversion or selectivity. It further reduces the downstream processing in some cases. The concept is proved for three representative systems, viz. esterification of lactic acid, aldol condensation of acetone and for esterification of fatty acid by methanol. Experimental proof is also provided in some cases.© Elsevie

Synthesis of methyl isobutyl ketone from acetone over metal-doped ion exchange resin catalyst

The kinetics of one-step synthesis of methyl isobutyl ketone from acetone was studied in the presence of the bifunctional commercial ion exchange resin, Amberlyst CH28 over a wide range of temperature, total pressure and catalyst loading in a batch reactor. An activity-based kinetic model is proposed to predict the observed results, with the non-idealities of the liquid phase being described using the UNIQUAC method. Formation of mesityl oxide was found to govern the overall rate of reaction. Low reaction rates were observed at higher conversion, possibly due to a pseudo-equilibrium caused by reversible deactivation of the catalyst as a result of formation of water in the reaction system. Simultaneous removal of water during the course of the reaction may result in an enhanced conversion.© Elsevie

Catalysis in multifunctional reactors

A multifunctional reactor is broadly defined as a multifaceted reactor system that combines a conventional reactor with any physical process to enhance the overall performance of the process to bring cost-effectiveness and/or compactness to a chemical plant. This multi-functionality can exist either on micro (catalyst) level or on macro (reactor) level [1]. There is substantial information available on several ways to achieve this task. Combining reaction with separation is one such popular approach. Here, when separation is performed in situ, several benefits like an increase in per-pass conversion and/or selectivity, energy integration, longer catalyst life, etc. are attained. When a separation process – e.g. distillation, adsorption, etc. – is to be performed simultaneously with a reaction, it imposes more restrictions on the reactor design so as to meet possible conflicting requirements that result from the reaction and separation. The existence of multiple phases as well as problems associated with heat and momentum transfer, mixing issues, etc. make the process complex, thereby attracting the attention of experts in reaction engineering, catalysis, modeling and simulation, and process design. Since catalysts are an integral part of a reactor system, many efforts have been made to manipulate its design to meet the above-mentioned challenges. A few examples are inserting special catalyst-filled envelopes into a distillation column to reduce pressure drop, manipulating the hydrophobicity of ion exchange resin in reactive chromatography for selective separation, grafting the catalyst in membrane material, etc. In this chapter, we review the recent literature on catalysts and their modified forms used in multifunctional reactors that combine reaction and separation. We restrict ourselves to the four most studied multifunctional reactors: reactive distillation, reactive stripping, membrane reactors and chromatographic reactors

In situ coating on cation exchange resin catalyst, Amberlyst-15, and its impact on the hydration of dicyclopentadiene

New phenomenon of in situ coating by the reactant/product on ion exchange resin catalyst, Amberlyst-15, that helps to improve the reaction kinetics of dicyclopentadiene (DCPD) hydration has been reported.© Elsevie

Attainable regions of reactive distillation-Part I. single reactant non-azeotropic systems

Reactive distillation (RD), a promising multifunctional reactor, can be used to improve the selectivity of the desired product by manipulating the concentration profiles in the reactive zone of the column. In this work, a new approach has been proposed to obtain the feasible regions of RD for the reactive systems involving single reactants, e.g. dimerization, aldol condensation, etc. Two new models namely the reactive condenser and the reactive re-boiler have been proposed. These models indicate the best location of the reactive zone in a column. Multistage versions of these models namely, reactive rectification and reactive stripping further expand the feasible region and are capable of representing the performance offered by a conventional RD unit. Several hypothetical non-azeotropic ideal systems have been extensively studied using these models and it has been shown that selectivity close to 100% is attainable over the entire range of conversion for a series as well as a combination of series and parallel reactions with positive reaction orders. Two industrially important cases of aldol condensation of acetone and dimerization of isobutylene have also been addressed using this approach. For porous catalysts, the presence of intra-particle diffusion resistance may limit the feasible region and even in the case of ideal non-azeotropic systems it may not be possible to obtain 100% selectivity. A methodology to incorporate pore diffusion effects is also illustrated.© Elsevie

Computational Modeling of Underground Coal Gasification

The book deals with development of comprehensive computational models for simulating underground coal gasification (UCG). It starts with an introduction to the UCG process and process modelling inputs in the form of reaction kinetics, flow patterns, spalling rate, and transport coefficient that are elaborated with methods to generate the same are described with illustrations. All the known process models are reviewed, and relative merits and limitations of the modeling approaches are highlighted and compared. The book describes all the necessary steps required to determine the techno-economic feasibility of UCG process for a given coal reserve, through modeling and simulation. © 2020 by Taylor & Francis Group, LLC

Simultaneous production of diacetone alcohol and mesityl oxide from acetone using reactive distillation

Dimerization of acetone (Ac) yields diacetone alcohol (DAA), which on further dehydration gives mesityl oxide (MO) along with various side-products. The reacting system is a combination of various series and parallel reactions. In the present work, the reaction is studied using a cation exchange resin (Amberlyst 15®) as catalyst. The effect of catalyst loading and temperature on reaction kinetics was evaluated and three models based on simplified Langmuir–Hinselwood mechanism are proposed. Aim of the work is to minimize undesired side-products and understand the effect of different parameters and operating modes on DAA:MO product ratio in reactive distillation (RD). It has been shown that the reaction when operated in a reactive rectification mode offers flexibility in the relative production rates of DAA and MO. The experimental results obtained are explained by simulation.© Elsevie

Fischer-Tropsch synthesis using bio-syngas and CO2

While Fischer-Tropsch synthesis (FTS) using coal and natural gas in conventional reactors is an almost well-established technology, the production of liquid hydrocarbons from syngas obtained from biomass is in its preliminary stages of commercialization in countries like Germany. With concerns about global warming and ways of disposing of CO2 being searched for, CO2 hydrogenation using FTS to liquid hydrocarbons can act as a CO2 sink. A brief review of FTS using CO2-rich syngas is given in this paper, looking at FTS as a technology that can help reduce global warming and as a process integration alternative. The reverse water gas shift (r-WGS) reaction is vital for CO2 hydrogenation. We have studied the effect of this using an FT kinetic model and have proposed a new flow sheet alternative for FTS using CO2-rich syngas. Simulations suggested that this new process gives better conversion of CO2. The product selectivity and yields from an FT plant are vital to make the process viable economically.© Elsevie