A method for facilitating the distribution of the flow of one or more streams within a bed vessel is provided. Disposed within the bed vessel are internal materials and structures including multiple operating zones. One type of operating zone can be a processing zone composed of one or more beds of solid processing material. Another type of operating zone can be a treating zone. Treating zones can facilitate the distribution of the one or more streams fed to processing zones. The distribution can facilitate contact between the feed streams and the processing materials contained in the processing zones.

A method for facilitating the distribution of the flow of one or more streams within a bed vessel is provided. Disposed within the bed vessel are internal materials and structures including multiple operating zones. One type of operating zone can be a processing zone composed of one or more beds of solid processing material. Another type of operating zone can be a treating zone. Treating zones can facilitate the distribution of the one or more streams fed to processing zones. The distribution can facilitate contact between the feed streams and the processing materials contained in the processing zones.

The invention relates to a catalyst system for producing maleic anhydride by means of the catalytic oxidation of n-butane, comprising at least one reactor tube, which has two catalyst layers consisting of different catalyst particles, characterized in that the geometric surface area per catalyst particle is greater in the catalyst layer that is first in the gas flow direction than in the second catalyst layer. The invention further relates to a process for producing maleic anhydride by means of the catalytic oxidation of n-butane, wherein a mixture of oxygen and n-butane is fed through the catalyst system according to the invention and the at least one reactor tube is at elevated temperature.