No abstract

The results of previous studies have been used to calculate the economically optimal reaction conditions in the production of high fructose syrup by isomerization over an Immobilized catalyst In a packed bed reactor. It is found that the optimum pH of the feed Is 7.65. The sensitivity of the total operation costs for small variations in the pH (0.1 pH unit) Is small. The temperature should preferably He between 50 and 55 °C or as close as possible to this range while avoiding microbiological growth In the system. The catalyst particles should be so small that their effectiveness factor Is unity. If unity cannot be reached for practical reasons, the particles should be as small as the pressure drop over the reactor allows.

Ind. Eng. Chem. Process Des. Dev. 1983, 22, 349-356 349 Guln, J. A.; Tarrer, A. R.; Lee, J. M.; Lo, L.; Curtls, C. W. Ind. Eng. Chem. Process Des. Dev. 1979, 18, 371. Guln, J. A.; Tarrer, A. R.; Lee, J. M.; Van Brackle, H. F.; Curtis, C. W. Ind. Eng. Chem. Process Des. Dev. 1970, 18, 631. Guin, J. A.; Lee, J. M.; Fan, C. W.; Curtis, C. W.; Lloyd, J. L.; Tarrer, A. R. Ind. Eng. Chem. Process Des. Dev. 1980, 19, 440. Hung. W. J.; Curtis, C. W.; Guin, J. A.; Clinton, J. H.; Barwood, H. L.; Tarrer, A. R. Paper 6d presented at Sprlng National AlChE Meetlng, Houston, TX, 1981a. Hunag, W. J.; Smith, N. L.; Guin, J. A.; Curtis, C. W.; Tarrer, A. R. Presented at 74th Annual AlChE Meeting, New Orleans, LA 1981b. Lambert. J. M.; Slmkovlch, 0.; Walker, P. L. Fuel 1980, 59, 687. Lowry, H. H., Ed. "Chemlstry of Coal Utilizatlon", Supplementary Volume; Wlley: New York; 1963; p 265-268. MazzOCco, N. J.; Klunder, E. 8.; Krastman, D. Pittsburgh Eng. Tech. Center, Phburgh, PA, Report No. DOE/PETC/Tl?-81/1, March 1981. Montano, P. A.; Granoff, B. Fuel 1980. 59. 214. Moroni, E. C. Paper 8a presented at Sprlng AIChE Meeting, Houston, TX, 1981. Neavei, R. C. Fuel 1976, 55, 237. Neavel, R. C. Phil. Trans. R . Soc. Lond. 1981. A300. 141. Orchin, M.; Storch, H. H. Ind. €ng. Chem. 1948, 40, 1385. Raaen, V. F.; Roark, W. H. Fuel 1978, 57. 650. Sapre, A. V.; Gates, B. C. Ind. €ng. Chem. Process Des. Dev. 1981, 20, Thomas, M. G.; Padrlck, T. D.; Stohi, F. V. Sandla Lab. Report SAND-80-Varghese, P.; Derbyshke, F. J.; Whltehurst, D. C. Paper 6b presented atThe rate of deactivation of an immobilized whole cell Arthrobacter glucose isomerase catalyst has been determined quantitatively as a function of a number of parameters. The deactivation is most senskive to pH and temperature, while other possible parameters, such as oxygen concentration, byproduct Concentration, and impurities present in a synthetic feed stream, appeared to have only a minor Influence on the rate of deactivation under normal process conditions. The deactivation is probably caused by denaturation of the enzyme and not by mechanisms such as proteolysis, change of the membrane structure of an Arthrobacter cell, or pore plugging.

SummaryThe relation between the intrinsic rate of the glucose-fructose isomerization catalyzed by whole-cell immobilized glucose isomerase and the substrate concentration can be described with the kinetic model ki kz G + E C X E C j ; l _ i L F + EThe numerical values of kl , k -k2. and k 2 have been determined from low-conversion experiments starting from pure glucose or fructose solutions, and are presented as a function of pH and temperature. The difference between the overall chemical reaction rate determined in high-conversion experiments and that calculated from the individual k , , k -,, k2, and k-2 values is less than 10%.

The investigated catalyst system consists of immobilized Arthrobacter cells containing the enzyme glucose isomerase, which catalyzes the isomerization of glucose into fructose. The internal structure of the catalyst was determined from electrom microscope photographs of replicas of freeze-etched catalyst. On the basis of the photographs a model for the internal structure of the catalyst was proposed. This structure was subsequently used to describe the reaction including mass-transfer effects. It appeared that under normal operating conditions the external mass-transfer rate does not influence the overall rate of reaction. The effect of internal mass-transfer resistances on the overall reaction rate can well be accounted for by the so-called porous sphere model. The intrinsic kinetics of the isomerization catalyzed by the present catalyst system can be represented by a modified Michaelis-Menten equation for a reversible one-substrate reaction.