The Experts below are selected from a list of 2037 Experts worldwide ranked by ideXlab platform
Ganapati D Yadav - One of the best experts on this subject based on the ideXlab platform.
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role of third phase in intensification of reaction rates and selectivity phase transfer catalyzed synthesis of benzyl phenyl ether
Industrial & Engineering Chemistry Research, 2007Co-Authors: Ganapati D Yadav, Omprakash V BadureAbstract:In the current work, the merits of the creation of a third phase in a typical biphasic reaction have been illustrated. The advantages of liquid-liquid-liquid phase-transfer catalysis (L-L-L PTC) have been brought out over liquid-liquid phase-transfer catalysis (L-L PTC) by considering the etherification of phenol by benzyl chloride to benzyl phenyl ether. L-L-L PTC is a novel strategy for waste reduction and improving profitability, in which a catalyst-rich middle phase is formed between the other two phases, wherein the main reaction takes place and intensifies the rates of reaction as well as offers better selectivity including catalyst reusability, unlike in the L-L PTC. The etherification of phenol with benzyl chloride under L-L PTC is accompanied by side reactions that lower the selectivity, and the catalyst cannot be recovered but wasted as an effluent, causing a load on the environment. However, the transformation of L-L PTC into L-L-L PTC leads to 100% conversion of the Limiting Reactant benzyl chloride with 100% selectivity to benzyl phenyl ether. The catalyst-rich phase is recovered and reused to some extent. This also helps in waste minimization, which is a major theme of green chemistry. The current work deals with the effects of different kinetic and processes parameters on enhancement in rates and selectivities in L-L-L PTC over L-L PTC. A mathematical model is also developed.
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novelties of reaction in the middle liquid phase in tri liquid phase transfer catalysis kinetics of selective o alkylation of vanillin with benzyl chloride
Applied Catalysis A-general, 2005Co-Authors: Ganapati D Yadav, Sharad V LandeAbstract:Abstract Reactions in three immiscible liquid phases (L–L–L) are attractive, and one of the phases can be the locale of reaction which will have a dramatic effect on product distribution in complex reactions. Thus, converting a bi-liquid system into a tri-liquid phase is of considerable scientific and commercial interest. 4-Benzyloxy-vanillin is used as a perfume and also as a starting material for synthesis of thalifoline and ephedradine as alkaloids and in synthesis of flavonoid compounds. Etherification of vanillin with benzyl chloride under biphasic phase transfer catalysis leads to formation of 4-benzyloxy-vanillin, but selectively suffers due to side reactions. Waste minimization is a major theme of green chemistry. In the traditional liquid–liquid phase transfer catalysis, the catalyst is not recovered but disposed off causing load on environment. However, the transformation of two-liquid phases into three-liquid phases L–L–L, PTC leads to 100% conversion of the Limiting Reactant benzyl chloride with 100% selectivity to 4-benzyloxy-vanillin, using TBAB as a catalyst. The rates of reactions are very high under L–L–L PTC, and reaction can be completed within 1 h as against 8 h required in L–L PTC. The catalyst-rich middle phase is recycled many times, thereby leading to profitability. The current work deals with effect of different kinetics and process parameters leading to enhancement in rates and selectivities and greener aspects of phase transfer catalysis.
Sharad V Lande - One of the best experts on this subject based on the ideXlab platform.
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novelties of reaction in the middle liquid phase in tri liquid phase transfer catalysis kinetics of selective o alkylation of vanillin with benzyl chloride
Applied Catalysis A-general, 2005Co-Authors: Ganapati D Yadav, Sharad V LandeAbstract:Abstract Reactions in three immiscible liquid phases (L–L–L) are attractive, and one of the phases can be the locale of reaction which will have a dramatic effect on product distribution in complex reactions. Thus, converting a bi-liquid system into a tri-liquid phase is of considerable scientific and commercial interest. 4-Benzyloxy-vanillin is used as a perfume and also as a starting material for synthesis of thalifoline and ephedradine as alkaloids and in synthesis of flavonoid compounds. Etherification of vanillin with benzyl chloride under biphasic phase transfer catalysis leads to formation of 4-benzyloxy-vanillin, but selectively suffers due to side reactions. Waste minimization is a major theme of green chemistry. In the traditional liquid–liquid phase transfer catalysis, the catalyst is not recovered but disposed off causing load on environment. However, the transformation of two-liquid phases into three-liquid phases L–L–L, PTC leads to 100% conversion of the Limiting Reactant benzyl chloride with 100% selectivity to 4-benzyloxy-vanillin, using TBAB as a catalyst. The rates of reactions are very high under L–L–L PTC, and reaction can be completed within 1 h as against 8 h required in L–L PTC. The catalyst-rich middle phase is recycled many times, thereby leading to profitability. The current work deals with effect of different kinetics and process parameters leading to enhancement in rates and selectivities and greener aspects of phase transfer catalysis.
M Colakyan - One of the best experts on this subject based on the ideXlab platform.
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comparison of trickle bed and upflow reactor performance at high pressure model predictions and experimental observations
Chemical Engineering Science, 1996Co-Authors: M R Khadilkar, Muthanna H Aldahhan, M P Dudukovic, M ColakyanAbstract:Comparison of laboratory trickle-bed and up-flow reactors over a range of operating conditions, which cover both gas and liquid Reactant limitations, has been investigated using hydrogenation of alpha-methylstyrene to cumene in a hexane solvent over 2.5% Pd on alumina extrudate catalyst as a test reaction. The results show that when the reaction is gas limited at low pressure and high liquid feed concentration, trickle bed reactor outperforms the upflow reactor. At high pressure and low liquid feed concentration, the reaction becomes liquid limited and upflow reactor performs better. It is concluded that the advantage of upflow or downflow depends on the reaction system type (i.e. whether the reaction is liquid or gas limited). A single criterion for identifying the Limiting Reactant is proposed which can explain most of the data reported in the literature on these reactors. Comparison of the experimental observations and the predictions of the reactor scale and pellet scale models available in the literature is presented.
Amiya K Jana - One of the best experts on this subject based on the ideXlab platform.
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dynamic simulation and nonlinear control of a rigorous batch reactive distillation
Isa Transactions, 2010Co-Authors: Prateek Kathel, Amiya K JanaAbstract:This work deals with the dynamics and control of a high-purity batch distillation column with chemical reaction. A heterogeneous esterification reaction between the acetic acid and butanol takes place to produce butyl acetate. The process model is formulated considering variable liquid holdup, UNIQUAC model for thermodynamic property predictions, nonlinear Francis weir formula for tray hydraulics, pseudohomogeneous model to represent the reaction kinetics and rigorous energy balance. A structured and simple iterative approach is devised to compute the vapor flows with the fast convergence, under the rigorous energy balance. The representative column is treated with a distillate policy based on which, the lightest product, water is removed as distillate at the starting of production phase. As a consequence, the column gets progressively richer with the main product, butyl acetate. In addition, almost complete conversion of the Limiting Reactant is achieved. In order to maintain the product purity at the top, a nonlinear generic model controller (GMC) in two different forms has been proposed. Finally, a comparative closed-loop performance is addressed. It is shown that the control scheme, along with the effective distillate strategy, leads to almost complete conversion of ingredients and high-purity products.
Vemuri Balakotaiah - One of the best experts on this subject based on the ideXlab platform.
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transport effects on pattern formation and maximum temperature in homogeneous heterogeneous combustion
Chemical Engineering Journal, 2016Co-Authors: Imran Alam, David West, Vemuri BalakotaiahAbstract:Abstract We study the impact of the Lewis number, Le f (thermal diffusivity of the reaction mixture to the molecular diffusivity of the Limiting Reactant) and the Peclet numbers on the maximum temperature attained for coupled homogeneous–heterogeneous combustion process in a parallel plate reactor using one, two and three-dimensional models. For the case of 1-D models, we find that the maximum temperature never exceeds the adiabatic value for physically consistent boundary conditions. For 2-D models, we find that for Le f 1 , the hot spot temperature can exceed the adiabatic value, it is always located on the wall and its distance from the inlet and magnitude increase with increasing radial Peclet number. However, for Le f > 1 , contrary to some literature claims (Zheng and Mantzaras, 2014), the peak temperature never exceeds the adiabatic value, though the temperature can be non-monotontic across the channel. We show that 3-D solutions can bifurcate either from 1-D or 2-D solutions irrespective of the value of the Lewis number. It is also shown that an infinite number of solutions that are discontinuous in the axial coordinate can exist for the common case of large axial heat Peclet number. The implications of these observations for catalyst and process design in systems in which both homogeneous and catalytic reactions occur are discussed.