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Van Der Zeijden D.,CRI Catalyst Leuna GmbH | Angueira E.,Criterion Catalysts
AIChE Ethylene Producers Conference Proceedings | Year: 2010

A well-designed way of removing acetylene is to convert it to ethylene by front end processing. The process is usually mediated by palladium-based fixed bed catalysts. From a catalyst vendor point of view, the challenge is to provide the industry with a catalyst that has long life, high stability, and simplicity in handling. A discussion covers the primary output of products from a steamcracker; CRI's outstanding range of catalysts for front end processing; CO swing stability; test run with catalyst KL7741B-T5 at CRI's test facilities; and catalyst KL7741B. This is an abstract of a paper presented at the 2010 Spring National Meeting San Antonio, TX 3/21-25/2010.

Knoche M.,CRI Catalyst Leuna GmbH
DGMK Tagungsbericht | Year: 2010

Maldistribution in trickle phase reactors is to be blamed for hot spot formation and non-ideal reaction. For a simple and quick evaluation, a virtually divided reactor model is presented for a better understanding and analysis of the consequences of liquid maldistribution. Based on this modelization, different methods are described to resolve microscopic and macroscopic maldistribution. The same model provides information to produce guidelines for reactor loading and evaluating the uneven effects of coking. It is shown that areas with specifically high liquid loads may suffer from insufficient gas supply and might therewith prevent a proper stoechiometric conversion of the gas with the liquid. In areas with lower liquid load, the gas has less hydraulic resistance and bypasses the effective reaction zone.

Pachulski A.,CRI Catalyst Leuna GmbH | Pachulski A.,TU Darmstadt | Schodel R.,CRI Catalyst Leuna GmbH | Claus P.,TU Darmstadt
Applied Catalysis A: General | Year: 2011

The selective hydrogenation of acetylene is one process to remove traces of acetylene from steam cracker cuts during the production of ethylene. Current disadvantages of commercially used Pd-Ag/Al 2O 3 catalysts applied in the C 2-tail end-selective hydrogenation are relative short cycle time (fast deactivation) caused by green oil formation and deposition of coke. Long-term tests were performed in a laboratory reactor under typical industrial conditions to investigate the deactivation of those catalysts. It was found that the Pd-Ag/Al 2O 3 catalyst with the highest long-term stability contains a Ag/Pd-ratio in the bulk of 0.41 and the lowest concentration of silver. This low silver amount causes a higher dilution of the palladium surface area than the higher silver amount within the investigated catalysts. This was indicated by CO chemisorption experiments, X-ray photoelectron spectroscopy (XPS), electron probe micro analysis (EPMA), X-ray fluorescence spectroscopy (XRF) and through the investigation of hydrocarbons deposited on the catalyst surface. The same catalyst sample was subsequently regenerated and tested in the laboratory reactor with respect to its long-term stability. The regenerated samples have the same long-term stability as the fresh sample if the regeneration procedure includes a hydrogen treatment. © 2011 Elsevier B.V.

Pachulski A.,CRI Catalyst Leuna GmbH | Pachulski A.,TU Darmstadt | Schodel R.,CRI Catalyst Leuna GmbH | Claus P.,TU Darmstadt
Applied Catalysis A: General | Year: 2012

The selective hydrogenation of ethyne is one process to remove traces of ethyne from steam cracker cuts during the production of ethene. Even though Pd-Ag/Al2O3 catalysts are predominantly used in industrial C2-tail end-selective hydrogenation reactors, a detailed kinetic study with this catalyst type has not yet been published in the open literature. For this reason, kinetic measurements were carried out on a Pd-Ag/Al 2O3 catalyst in an integral fixed bed reactor at different process conditions for the selective hydrogenation of ethyne. The results of these measurements were fitted on different kinetic models ranging from a classical Hougen-Watson, Langmuir-Hinshelwood and Rideal-Eley approach up to simple power law equations. The kinetic model with the best fit was found by statistical and thermodynamical evaluations of all models and their respective kinetic parameters. This model is based on a Langmuir-Hinshelwood reaction mechanism involving two different active sites for the hydrogenation of ethyne and ethene. The kinetic measurements were not dependent on mass and heat transfer as demonstrated by using the criteria from Mears and the Weisz-Prater as well as for the Damkoehler numbers in 3rd and 4th order. Finally the performance of a bypass reactor, running in parallel to an industrial C 2-tail end-selective hydrogenation reactor, was successfully calculated with a reactor model. © 2012 Elsevier B.V.

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