Absorption accompanied with chemical reaction in trickle-bed reactors.

A new development in the field of internals in packed columns is the use of structured packing types. Recently, a new structured packing type coated with a thin alumina layer (KATAPAKTM) has been developed. In this report, the results of an experimental and theoretical study concerning the possible applicability of this new packing material for hydrogenation processes in a trickle-bed reactor is presented. The palladium catalyzed hydrogenation of α-methylstryrene is used as a model reaction to study hydrodynamics and mass transfer characteristics in a trickle-bed reactor under reactive conditions. Converstions at several process conditions are measured in a pilot plant in which 3 mm spheres as well KATAPAKTM is applied as packing materials. A comparison of the results of some physical absorption experiments with the results of hydrogenation experiments showed that the resistance in series model—in which the total resistance against mass transfer is calculated from the separate resistances—is not valid in systems where heterogeneous reactions at the solid surface can enhance the mass transfer-rate at the gas-liquid interphase. With the aid of a developed trickle-bed reactor model, based on liquid diffusion, simultaneous reaction at the solid surface and zero volume mixing points, the mass transfer phenomena in trickle-bed reactors in conditions where the resistance in series model fails can be explained and described. The numerically solved model calculates the hydrogen profiles in the liquid films of the reactor and over all single pass conversions at several process conditions. These conclusions are confirmed by the results of the simulation of a model reactor, i.e. the laminar film reactor with a catalytically active wall. From the results of the measurements it could be concluded that in trickle-flow conditions, the application of KATAPAKTM does not significantly improved on the overall performance of trickle-bed reactors. The increase of the physical absorption rate due to better mass transfer characteristics of structured packings compared to dumped packing types—as reported in literature—will be eliminated to a certain extent in reactive systems due to the enhancement effect of heterogeneous reactions in trickle-flow operation

Belbin Revisited: The Construct Validity of the Interplace II Team Role Instrument

In the present study the construct validity of the revised edition of the Belbin Team Roles measure, the so-called Interplace II program, is tested. Three parallel parts were used to determine someone’s team roles. The sample included 1434 persons who were asked to fill out the self-perception inventory and the self-perception assessment, whereas the observer assessment sheet was filled out by at least four observers. The inter-rater reliability appeared to be satisfactory across all team roles. As for the construct validity, which was studied in a multitrait-multimethod design using structural equation modeling, the results revealed that the discriminant and convergent validity for the instrument as a whole is good; only a small effect could be contributed to method variance.Belbin;multitrait-multimethod methodology;team roles;teams

Leadership Behaviour and Upward Feedback: Findings from a Longitudinal Intervention

A sample of 48 managers and 308 staff members of a community health care organization took part in a study to investigate the influence of participating in an upward feedback program on leadership behaviour, both as indicated be self-ratings and subordinates’ ratings. The research design consisted of three measurement points within one year. The intervention included managers receiving upward feedback and a management skills workshop. The results showed a negative effect of the program on leadership behaviour as rated by the staff. Furthermore, managers reduced their self-ratings in the condition where they participated in both a feedback session and an management skills workshop.Management;Leadership Behaviour;Self-rating;Upward Feedback

Understanding servant leadership

The 21st century has brought much in the way of turmoil and change to the world of business. As a consequence, ways of doing business that were once universally accepted now seem outdated and inflexible in an age where knowledge drives economies and socially responsible corporate attitudes influence stakeholders and shareholders alike

Evaluer des compétences en mathématiques dans le cadre d’une épreuve externe à large échelle au départ de tâches complexes, de tâches décomposées et de tâches élémentaires : quel pouvoir informatif?

peer reviewe

Single step spray-dried polyelectrolyte microparticles enhance the antigen cross-presentation capacity of porcine dendritic cells

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