Operability of an Industrial Methanol Synthesis Reactor with Mixtures of Fresh and Partially Deactivated Catalyst

Abstract

Disposal of spent catalyst is a common practice in industrial methanol synthesis. However, the spent catalyst has, generally, a good level of activity and can be used if mixed with fresh catalyst. In this work the operation of an industrial methanol synthesis reactor with mixtures of fresh and partially deactivated catalyst was investigated using a one-dimensional transient model. Analysis of the deactivation behavior of low-pressure methanol synthesis catalyst shows there is an extremely sharp rate of deactivation in a small part of the catalyst life-time, which is followed by a relatively slow rate of deactivation in the remaining catalyst cycle-time. Different configurations were studied for catalyst recycling, and two limiting cases are discussed in detail in this paper, namely layered and homogeneous (mixed) bed models. In the first one, the catalyst was segregated into two alternate layers of fresh and partially deactivated catalyst, while in the second homogeneity of the catalyst bed was simulated by segregating a large number of alternate layers of fresh and partially deactivated catalyst. It was observed in both cases that when catalyst recycling is used, the process does not depart significantly from the standard operating conditions, and also that the mixed bed had less influence on the reactor performance than layered one.

Incorporation of Dynamic Flexibility in the Design of a Methanol Synthesis Loop in the Presence of Catalyst Deactivation

“…The mole fraction of methanol in a fresh feed stream is generalized. Therefore, all streams consist of CH 3 OH, CO 2 , CO, H 2 O, H 2 , N 2 and CH 4 . For simulation of the loop, the specification of streams must be obtained.…”

“…The fresh feed also contains CH 4 and N 2 , which are not incorporated in the reaction for methanol production. Although the dehydration of synthesis gas is performed, some traces of water can remain in the synthesis gas.…”

“…Such a reactor usually resembles a vertical shell and tube heat exchanger [4]. The tubes are packed with catalyst pellets and boiling water circulates in the shell side to remove the heat from the exothermic reactions.…”

A Novel Radial‐Flow, Spherical‐Bed Reactor Concept for Methanol Synthesis in the Presence of Catalyst Deactivation

“…The mathematical model corresponding to the spherical packed bed flow reactor (SPFR) is derived by starting from the dynamic model developed by Rahimpour et al [10] for tubular flow reactors, and implementing the corresponding changes for a spherical geometry. In this study, homogeneous, one-dimensional models have been considered.…”

“…Rahimpour et al studied the deactivation of a methanol synthesis catalyst and proposed mechanisms for deactivation of this type of catalyst [8,9]. Rahimpour et al also studied the reactor performance when a mixture of fresh and partially deactivated catalyst was used [10]. Velardi and Barresi proposed a multi-stage methanol reactor network with auto-thermal behavior to promote the reactor performance [11].…”