09:30
Unconventional catalytic reactors 1
Chair: Miguel Menendez
09:30
40 mins
#88
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KEYNOTE: Structured reactors under inductive heating
Prof. Evgeny Rebrov
(presenter: Evgeny Rebrov)
Abstract: Trickle bed reactors are employed in many chemical and fine chemical applications. Conventional fixed bed and trickle bed reactors suffer from the non-uniform temperature distribution and the formation of hot spots. We introduced a novel concept of an inductively heated micro-trickle bed reactor with several adjacent thermal zones. In these reactors, catalytic zones are separated with several nickel ferrite heating zones. This configuration creates a possibility to make a few reaction zones with different temperatures, while still being compact enough to use in a single fixed bed reactor. Such configuration has an inherently large surface area-to-volume ratio, offering high heat and mass transfer rates, which is beneficial for attaining high selectivities and conversions and enables optimum control of residence time and temperature distribution. It also holds large promise for the development of miniaturized chemical synthesis devices, where several catalytic zones are integrated with microstructured sensors and actuators.
In this lecture, we provide an overview of the design methodology of a multizone zone structured reactor based on a convection and conduction heat transfer model [3]. A scale-up approach to a 10 kg/day production scale will be presented and demonstrated with several examples.
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10:10
20 mins
#31
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UNDERSTANDING COMPLEX CATALYTIC PROCESSES BY UTILIZING THE PROFILE REACTOR TECHNIQUE
Michael Geske, Ying Dong, Gudrun von der Waydbrink, Eugen Stotz, Robert Schlögl, Raimund Horn, Frank Rosowski
(presenter: Michael Geske)
Abstract: The tailor-made catalyst development for an industrial process needs the joint effort of many groups. The here presented Profile Reactor Technique is an important part of the toolbox to understand underlying reaction processes and improve catalysts and/or reaction conditions by knowledge-based design. The Oxidation of Butane to Maleic Anhydride (incl. side products as carbon monoxide, carbon dioxide, acetic acid and acrylic acid) is chosen as test case.
The catalyst analyzed is a pelletized Vanadium Phosphorus Oxide. In the first place, parameter field studies were performed to develop a kinetic model for later CFD simulation. Unfortunately, intrinsic species reaction pathways remain hidden as only entrance / exit data are measured. The Profile Reactor1 can give insight with spatially resolved temperature and gas composition measurements along the centerline axis of the catalyst bed (0.5 m, 100 g scale). It is possible to follow evolution of intermediate species and their concentration profiles in mm resolution, including often omitted transport phenomena2 – Fig. 1. The profiles reveal a nonlinear development of n-butane conversion. The temperature profile shows a 55 K hotspot, which correlates with the formation of acrylic acid as intermediate product.
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10:30
20 mins
#42
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REVERSE ENGINEERING OF COMMERCIAL SPECTROSCOPIC CELLS USED AS OPERANDO REACTORS
José Valecillos, Gorka Elordi, Andrés T. Aguayo, Javier Bilbao, Pedro Castaño
(presenter: Pedro Castaño)
Abstract: We prove here the limitations and prospects of conventional spectrocospic cells used as operando catalytic reactors for obtaining intrinsic kinetic measurements. The information is potentially useful for prototyping unconventional operando reactors. We have used two commercial cells with horizontal (H) or vertical (V) arrangement of the catalyst disc (compressed powder) within the geometries displayed in Fig. 1. Tracer injection experiments under different gas flow rates have been performed in order to assess the residence time distribution through the E curves (Fig. 1). The cells have been used for the methanol to hydrocarbon reaction at different catalyst-gas contact times (W/F) at 400 ºC and using a HZSM-5 catalyst. Similarly, we have used a fixed-bed reactor using comparable conditions, aiming an intrinsic kinetic model of the reaction. Comparing the performance of the operando reactor with the intrinsic kinetic model, we have been able to discriminate the conditions of each cell to has predictable external mass transfer limitations. On the other hand, we have observed severe internal mass transfer limitations, with a selective deposition of hydrocarbon species in the reaction within the first 10 µm of depth (Fig. 1).
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10:50
20 mins
#46
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PERIODICALLY OPERTATED CATALYTIC REACTOR FOR METHANOL SYNTHESIS – LOOKING FOR THE BEST SCENARIO
Menka Petkovska, Daliborka Nikolic, Tamara Milicic, Carsten Seidel, Achim Kienle, Andreas Seidel-Morgenstern
(presenter: Menka Petkovska)
Abstract: Forced periodic operations, as a potential way of improving reactor performance, have been known and investigated for decades[1]. In our research, we have developed a new, fast and easy analytical method based on nonlinear frequency response (NFR) analysis for evaluating performances of forced periodically operated reactors. The method gives the answers to the following: which input modulations can improve the reactor performance, what are the optimal forcing parameters and what is the magnitude of the expected improvement. The starting point for applying the NFR method is a nonlinear mathematical model of the reactor[2].
In this work, the NFR method is implemented for evaluation of a periodically operated reactor for the reaction of methanol synthesis by hydrogenation of CO and CO2, using a standard Cu/ZnO/Al2O3 catalyst. A lumped kinetic model of methanol synthesis with 14 parameters[3], estimated from an extensive experimental investigation[4], is used. The potential modulated inputs are the mole fractions of CO, CO2 and H2 in the feed stream and the feed flow-rate, as well as their combinations. The NFR method is used in order to find the best scenario which would result with the highest methanol productivity.
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