“…This perspective can be developed by employing a variety of contexts including different membrane separation processes, different membranes, chemical/electrochemical reactions, enzymatic processes, fermentations, catalyst immobilization/segregation, catalytic membranes, integration of functions etc. In the case of separation from liquid reaction mixture, reverse osmosis (Vasudevan et al, 1987), ultrafiltration (Cheryan and Mehaia, 1986;Closset et al, 1973), pervaporation (David et al, 1991;Strathmann and Gudernatsch, 1991), gas separation membranes (Sirkar, 1992;Twardowski and McGilvey, 1987), vacuum membrane distillation, electrodialysis (Strathmann, 1992), liquid membranes (Ricks et al, 1992) can be used. The separation may be purification, enrichment, or concentration.…”
The pervaporation reactor is, specifically, the new technology for reaction and separation. It is rather difficult to predict the market potential of processes newly introduced on the market. However, in comparing investment costs, environmental aspects of pervaporation systems with those of conventional processes, it can be said that pervaporation reactor will play an important role in the chemical industry for new installations as well as for rehabilitation of existing plants. Techno-economic studies are showing that pervaporation reactors have good market potential. There are many examples where pervaporation reactors can reduce product costs by an important margin. The most common reaction system studied for the application of pervaporation is an esterification reaction between an alcohol and an acid in the presence of a highly acidic catalyst (e.g., concentrated sulfuric acid). In the present paper, modified/improved model for pervaporation reactor for benzyl alcohol acetylation is presented. The parametric sensitivity is studied for the performance of pervaporation reactor. The use of pervaporation coupled to the esterification reaction increases the conversion considerably. The modified model allows the evaluations of the reaction time necessary to achieve a given conversion. The model makes it possible to determine the membrane surface area / operating time ratio for a given conversion. The present model can be extended for the other esterification reactions in pervaporation reactors.
“…This perspective can be developed by employing a variety of contexts including different membrane separation processes, different membranes, chemical/electrochemical reactions, enzymatic processes, fermentations, catalyst immobilization/segregation, catalytic membranes, integration of functions etc. In the case of separation from liquid reaction mixture, reverse osmosis (Vasudevan et al, 1987), ultrafiltration (Cheryan and Mehaia, 1986;Closset et al, 1973), pervaporation (David et al, 1991;Strathmann and Gudernatsch, 1991), gas separation membranes (Sirkar, 1992;Twardowski and McGilvey, 1987), vacuum membrane distillation, electrodialysis (Strathmann, 1992), liquid membranes (Ricks et al, 1992) can be used. The separation may be purification, enrichment, or concentration.…”
The pervaporation reactor is, specifically, the new technology for reaction and separation. It is rather difficult to predict the market potential of processes newly introduced on the market. However, in comparing investment costs, environmental aspects of pervaporation systems with those of conventional processes, it can be said that pervaporation reactor will play an important role in the chemical industry for new installations as well as for rehabilitation of existing plants. Techno-economic studies are showing that pervaporation reactors have good market potential. There are many examples where pervaporation reactors can reduce product costs by an important margin. The most common reaction system studied for the application of pervaporation is an esterification reaction between an alcohol and an acid in the presence of a highly acidic catalyst (e.g., concentrated sulfuric acid). In the present paper, modified/improved model for pervaporation reactor for benzyl alcohol acetylation is presented. The parametric sensitivity is studied for the performance of pervaporation reactor. The use of pervaporation coupled to the esterification reaction increases the conversion considerably. The modified model allows the evaluations of the reaction time necessary to achieve a given conversion. The model makes it possible to determine the membrane surface area / operating time ratio for a given conversion. The present model can be extended for the other esterification reactions in pervaporation reactors.
“…Reverse Osmosis. Vasudevan et al have described a membrane sandwich reactor in which the Saccharomyces cerevisae (ATCC 4126) cells were effectively placed between an ultrafiltration (UF) membrane and a reverse osmosis (RO) membrane; the reactor was fed with a solution of glucose at a high pressure from the UF membrane side and the product solution was forced out through the RO membrane. The product solution concentration progressively increased in ethanol; the glucose in the feed solution was effectively rejected by the RO membrane.…”
mentioning
confidence: 99%
“…The membranes in this reactor separate the product ethanol from the reactant glucose and effectively immobilize the biocatalyst (whole cell). 3 Membrane “sandwich”: (1) UF membrane, (2) coarse filter paper (>10 μm), (3) cell mass, (4) fine filter (0.2 μm, microporous), and (5) RO membrane (reprinted from Vasudevan et al with permission).…”
mentioning
confidence: 99%
“…Membrane “sandwich”: (1) UF membrane, (2) coarse filter paper (>10 μm), (3) cell mass, (4) fine filter (0.2 μm, microporous), and (5) RO membrane (reprinted from Vasudevan et al with permission).…”
Membrane reactors have found utility in a broad range of applications including biochemical,
chemical, environmental, and petrochemical systems. The variety of membrane separation
processes, the novel characteristics of membrane structures, and the geometrical advantages
offered by the membrane modules have been employed to enhance and assist reaction schemes
to attain higher performance levels compared to conventional approaches. In these, membranes
perform a wide variety of functions, often more than one function in a given context. An
understanding of these various membrane functions will be quite useful in future development
and commercialization of membrane reactors. This overview develops a functional perspective
for membranes in a variety of reaction processes. Various functions of the membranes in a reactor
can be categorized according to the essential role of the membranes. They can be employed to
introduce/separate/purify reactant(s) and products, to provide the surface for reactions, to provide
a structure for the reaction medium, or to retain specific catalysts. Within these broad contexts,
the membranes can be catalytic/noncatalytic, polymeric/inorganic, and ionic/nonionic and have
different physical/chemical structures and geometries. The functions of the membrane in a
reaction can be enhanced or increased also by the use of multiple membrane-based schemes.
This overview develops a perspective of each membrane function in a reactor to facilitate a better
appreciation of their role in the improvement of overall process performance.
“…We have proposed in our earlier reports a bioreactor in which living yeast cells are sandwiched between an ultrafiltration (UF) membrane and a reverse osmosis (RO) membrane (Vasudevan et al, 1987(Vasudevan et al, , 1988. A solution containing glucose substrate and nutrients is in contact with the ultrafiltration membrane, and pressure is applied on the feed substrate solution.…”
A transport study has been conducted for a multilayer UF membrane/dead cell layer/RO membrane system in order to isolate the permeation phenomena of solvent (water) and glucose solute occurring during the bioreaction. It has been found that the transport can be described considering the above system as a series of four barrier layers, including a concentrated boundary layer, a UF membrane, a cell layer, and a RO membrane. While convective and diffusive transport mechanisms are combined
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