Temperature Profiles and Process Performances of Sponge Packings As Compared to Spherical Catalysts in the Oxidation of o-Xylene to Phthalic Anhydride

Abstract

The oxidation of o-xylene to phthalic anhydride was carried out in a pilot plant with a tubular reactor in order to investigate the heat transfer properties of different types of catalytic fixed beds through analysis of the temperature profiles arising upon polytropic o-xylene conversion. Ceramic sponges of different materials and pore densities were compared to a packed bed of spheres, all of which were coated with novel flame-made vanadia/titania catalyst nanoparticles. The temperature profiles were smoother and hot spot temperatures were found to be lower when sponges were employed as catalyst supports. The strongest reduction of the hot spot temperature was achieved with a sponge packing made of silicon carbide, showing the potential to significantly improve the productivity of the process.

Performance and Kinetics of Flame-Made Vanadia/Titania Catalyst Nanoparticles in the Partial Oxidation of o-Xylene

“…It is worth mentioning here that the different supports do not influence the catalytic behavior of the flame-made catalyst by any kind of chemical interaction, as it was shown in a previous publication. 18 2.1. Catalyst Preparation.…”

“…Sponges made of materials with high thermal conductivity (e.g., silicon carbide) were found to improve heat removal from the catalyst bed to such an extent that the STY of PA could be doubled as compared to a fixedbed of ceramic spheres coated with the same V 2 O 5 /TiO 2 active material. 18 To predict and to improve the performance of a catalytic reactor at industrially relevant conditions, the knowledge of the reaction kinetics is indispensible. In the case of the oxidation of o-xylene to PA, several kinetic studies have been published already.…”

“…The kinetics deserves a separate study because this catalyst not only is considerably more active than conventionally prepared vanadia/titania but also yields less intermediate products (TA, PH) at high conversions. 18 Vanadia/ titania catalysts for PA production should be employed as coatings on ceramic supports. For the work presented here, we used ceramic sponges and ceramic spheres as carriers.…”

High Temperature Applications of SiSiC Cellular Ceramics

“…[24] Foams offer several advantages compared to the other two structures: higher radial mass flow, higher radial heat exchange, higher tortuosity of the flow resulting in more interesting fluid dynamics, lower pressure drop, and a higher geometrical porosity. [26] The catalyst carriers were coated with a vanadia/titania catalyst and fitted in a tube reactor. [1] The use of SiÀSiC foams, compared to other materials, is justified for reactions that take place in acid or basic conditions or reactions for which high thermal conductivity of the catalyst carrier is necessary.…”

Highly conductive “packed foams”: A new concept for the intensification of strongly endo- and exo-thermic catalytic processes in compact tubular reactors

“…It is widely recognized that spatially structured reactors are at the very heart of process intensification [1,2] and it has been shown that significant enhancement of radial heat transfer rates in multitubular catalytic reactors with external cooling can be achieved if the random packings of catalyst pellets are replaced by structured catalysts with thermally connected, highly conductive foams [3][4][5][6]. Nevertheless, some issues still exist that prevent the application of this technology at the industrial scale.…”