linked H+ cations are the acid sites Sucrose under- goes acid hydrolysis into glucose and fructose (stereo-isomers) according to a pseudo-first order reaction
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[PDF] Acid-catalyzed hydrolysis of sucrose: A student study of a reaction
Acid-Catalyzed Hydrolysis of Sucrose A student study of a reaction mechanism H++~GLUCOSE = a GLUCOSE Figure 1 For dilute solutions of acids the most
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1 fév 2013 · 1 INTRODUCTION The acid-catalyzed hydrolysis of sucrose has a long history ( Scheme 1) It would be the first catalytic reaction that was
Acid-Catalyzed Inversion of Sucrose in the Amorphous State at Very
most likely had undergone acid-catalyzed inversion to glucose Evgenyi Y Shalaev,1 citric acid to sucrose (1:10), and hence the same Tg, the rate of reaction the overall catalyzed sucrose hydrolysis in an amorphous polymeric matrix 13
[PDF] Sucrose Inversion: An Experiment on Heterogeneous Catalysis* - IJEE
linked H+ cations are the acid sites Sucrose under- goes acid hydrolysis into glucose and fructose (stereo-isomers) according to a pseudo-first order reaction
[PDF] Inversion of Sugar : The hydrolysis of sucrose by boiling with a
wave height of fructose has been used to investigate the inversion of sucrose The hydrolysis of sucrose by boiling with a mineral acid, or by the enzyme invertase, produce a The constant value of k shows that the reaction is of first order
THE EFFECTS OF HIGH PRESSURE ON THE - ScienceDirect
the mechanism of sucrose inversion mere uncovered A few attempts appeared to inhibit sucrose hydrolysis catalyzed by HCl to a very small degree He assumed that the effect was due to a decrease of acid dissociation under pressure
[PDF] Inversion of Sucrose
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Sucrose Inversion: An Experiment on
Heterogeneous Catalysis*
ADEÂLIO MENDES, FERNAÄO D. MAGALHAÄES and LUIS M. MADEIRADepartamento de Engenharia Quõ
Âmica, Faculdade de Engenharia, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto, Portugal. E-mail: mendes@fe.up.pt Illustration of heterogeneous catalysis concepts in laboratory courses is not usually simple or economical. For our undergraduate senior lab course we have developed an environmentally friendly experiment dealing with several aspects of heterogeneous catalysis, having in mind the use of readily available and relatively inexpensive equipment and chemicals on a compact setup, which students can safely operate. The experiment deals with the acid-catalyzed sucrose inversion, performed in packed bed chemical reactors, where the catalyst is a cation-exchange resin in the H form. An additional reactor is included for illustrating an enzyme-catalyzed system. The conversion achieved is determined using the Flow Injection Analysis technique.NOMENCLATURE
C sucr sucrose concentration, within the catalyst pellet (mol/m 3 C ssucr sucrose concentration at the catalyst surface conditions (mol/m 3 D e effective diffusivity (m 2 /s) d p particle diameter (m)E...t†residence time distribution function
fdimensionless sucrose concentration profileFfeed flow rate (m
3 /s) kintrinsic rate constant (s ±1 k obs observed rate constant (s ±1Lbed length (m)
PePeclet number
rradial distance (m) r 0 particle radius (m) ttime (s) usuperficial velocity (m/s)Vreactor volume (m
3 X sucr sucrose conversion zdimensionless radius directionGreek Symbols
"bed porosityThiele modulus
internal effectiveness factor fluid viscosity (Ns/m 2 fluid density (kg/m 3 space-time (s)INTRODUCTION
HETEROGENEOUS CATALYSIS is a topic of
great industrial importance in Chemical Engi- neering and consequently plays a significant role in theoretical undergraduate courses. In fact,heterogeneous catalysis is present in most of chemical reaction engineering (CRE) handbooks, e.g. [1±4], and is an essential part of the majority of the undergraduate CRE courses [5±9]. This paper describes an experimental set-up on heterogeneous catalysis, running at a chemical engineering laboratory discipline, taught during the 1st seme- ster, 4th curricular year of the 5 years longChemical Engineering course at the University of
Porto, Portugal.
All the experiments now available at this
laboratory were designed having in mind: high safety, low investment andoperation costs,reduced environmental impact and high didactic content.The sucrose inversion (hydrolysis) is acid-
catalyzed and can be conducted in a fixed bed, packed with a cation-exchange resin in the proto- nic form. This is the kind of experiment that fits perfectly the above mentioned principles and succeeded to capture the attention of an interna- tional company dedicated to the manufacture and commercialization of this kind of equipment [10].The resin's three-dimensional network forms a
macroporous structure in which the ionically linked H cations are the acid sites. Sucrose under- goes acid hydrolysis into glucose and fructose (stereo-isomers) according to a pseudo-first order reaction [11, 12]: C 12 H 22O 11 ‡H 2
Oÿ!
H C 6 H 12 O 6 ‡C 6 H 12 O 6 ...1†The optical rotation of sucrose is positive
20Dˆ‡66.58) and its hydrolysis with an acid
yields a 1:1 ratio of D-(‡) glucose and D-(ÿ) fructose, with positive and negative optical rotations, respectively. Since fructose has a greater optical rotation than glucose (ÿ92.48versus 52.78), * Accepted 19 January 2003. 893Int. J. Engng Ed.Vol. 19, No. 6, pp. 893±901, 20030949-149X/91 $3.00+0.00 Printed in Great Britain.#2003 TEMPUS Publications. tionproceedstocompletion.Thisiswhyitis usuallycalledsucroseinversionreaction.