Fig 14 - uploaded by Vivek Talnikar
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Schematic representation of continuous reactive distillation column. Key: R -rotameter; S -sample point; T -temperature indicator (numbers indicate sections) (ID À 0.0508 m (2"); total height À 3.55 m).
Source publication
The present work explores the recovery of trifluroacetic acid (TFA) by reactive distillation (RD) from dilute aqueous solutions. For this purpose, the reaction of TFA with methanol was chosen. Batch kinetic runs were initially conducted and low conversions were achieved. In order to improve upon this, RD runs were conducted in both batch mode as we...
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The process of producing esters is usually performed through esterification in a reactor followed by a distillation column to separate the products. However, this design limits the reagent conversion. Reactive distillation is an alternative to get around this issue as it allows greater reagent conversions in reactions limited by chemical equilibriu...
Citations
Esters of trifluoroacetic acid are compounds having important applications in the process industry. Methyl trifluoroacetate (MTFA) is useful as an intermediate in the manufacture of valuable pharmaceutical and agriculture chemicals. This work has investigated transesterification of ethyl trifluoroacetate (ETFA) to MTFA using Amberlyst-15. Evaluation of reaction kinetics was followed by regression to obtain kinetic parameters. Packed bed reactor experiments were performed thereafter to improve the process and to make the process continuous, wherein conversion of 76% was achieved in 5 h under the conditions used. Starting from a mixture of reactants, a complete process to obtain pure MTFA was developed in this work. For this, liquid-liquid extraction, adsorption over molecular sieves followed by distillation was used.
Manufacture of methyl butyrate is presented in this work at different reaction conditions using ion exchange resins as catalyst. With T − 63 as the catalyst, about 38% conversion was obtained at 333 K, mole ratio of 1:1 and 900 rpm. Water was seen to inhibit the reaction, and hence packed bed reactor was used to improve the conversion. Conversion increased to about 60%, thus showing that there is possibility of process intensification.
The synthesis of isoamyl propionate by esterification of propionic acid with isoamyl alcohol is presented in this work using ion exchange resin Amberlyst-15. In batch kinetics, about 33% conversion of acid was obtained in 3 hours under the conditions such as temperature of 343 K, 1:3 molar ratio, Amberlyst-15 catalyst with 5% loading (w/w of limiting component). For enhancing the performance of the reaction and to make the process continuous, the reaction was conducted in a packed bed reactor. Conversion of 53% was obtained in 3 hours, thus indicating the possibility of process intensification.
Samples of commercial silicate glass have been subjected to ion-exchange by silver ions. The ion-exchange was performed at 320°C for duration between 2 and 60 minutes, in a molten mixture of AgNO3 and NaNO3 with molar ratio of 1:99, 5:95 and 10:90. The ion-exchange process was followed by different treatments: thermal annealing, gamma-irradiation and their combined role in order to initiate the synthesis and control of silver aggregates in the surface of glass matrix. UV-Visible absorption spectrometry results indicated that various states of silver existing in these glasses depend on heat treatment conditions. The Ag+ ions exist in almost all conditions, neutral silver atoms (Ag0) exist only in samples subjected to heat treatment in the range 250-450°C and silver aggregates (Ag0)n produced by thermal annealing at 550°C were responsible for the absorption bands observed around 305, 350 and 450 nm respectively. The only effect of gamma-irradiation with doses between 10-100 kGy and combined with thermal annealing on glass samples was also investigated. The main modification induced by gamma rays on the structure of silicate glass was the creation of colour centres, the non-bridging oxygen hole centres (NBOHCs) and the trapped electrons. The NBOHCs defects caused the absorption of light.. The Ag+ ions trapped electrons to form neutral silver Ag0. The first step of aggregation was observed following the irradiation by gamma rays, as well as after thermal annealing. After annealing at 550°C, silver atoms diffused in glass surface to form silver aggregates. An absorption band at 430 nm was observed characterising the Surface Plasmon Resonance (SPR) of silver aggregates. The calculated average radii increase from 0.9 to 1.35 nm when the annealing time increase from 10 to 490 min.
Ion-exchange resins (IERs) possess the capability of catalyzing several classes of reactions, apart from their ability to make separations. In fact, it is possible to synthesize tailor-made IERs for the reactive processes at hand. Use of IERs can fetch a number of advantages compared to those of homogeneous catalysts and other solid catalysts. Reactive separation (RS) is a relatively new process technology that has the potential to offer several advantages over the conventional approach of reaction followed by separation. Various separation steps can be coupled with the reaction, including: distillation, extraction, chromatography, crystallization and separation by membranes. This chapter reviews the salient features and industrial applications of reactive separations using IERs.
The reaction of acrylic acid and 2-ethyl-1 hexanol was explored in this work with the intent of process intensification. In order to assess the effect of important parameters on the course of reaction, this work initially conducted batch reactor experiments. Reaction conditions in the batch reactor for a specific conversion (~ 30 %) were obtained. A kinetic model was then obtained through regression to arrive at a rate expression that is later used in process development. Experiments were performed in the reactive distillation (RD) environment in batch mode, which showed substantial increase in conversion (~ 80 %) indicating the applicability of RD. Further, this work performed simulation in the RD environment to assess process intensification. Simulations show that it is possible to obtain complete conversion of the acid.
