Consequences of catalyst deactivation for process design and operation

Catalyst deactivation has important consequences for the design of a proces s and the way it is operated. The nature of the deactivation, and in partic ular the question whether it can be reversed under conditions which are com patible with the normal operation or whether a separate regeneration treatm ent of the catalyst is required to restore its activity, as well as the tim e-scale of the deactivation determine the type of technology that is feasib le and process options like reactor type and process configuration. This re lationship between deactivation behaviour and process lay-out forms the sub ject matter of the present paper. The general principles that guide the choices of process type and parameter s are illustrated in more detail with examples from the fields of catalytic reforming of petroleum naphtha and hydroprocessing of petroleum residues. In these fields, different catalyst deactivation mechanisms are operative a nd catalyst deactivation rates can vary widely depending upon feedstock and process parameters. Consequently, different reactor technologies and proce ss configurational choices are possible. The relation between catalyst deac tivation behaviour and process design and operation can be viewed from two sides: on the one hand, the deactivation behaviour may dictate the choice b etween viable process options and may provide an incentive for the developm ent of novel technology that can cope optimally with the demands set by the deactivation of the catalyst. On the other hand, the introduction of novel technological options may widen the scope of a process, e.g. by opening th e possibilities to apply novel catalysts or to operate under unconventional conditions that lead to a more economic or otherwise better process, possi bilities that were previously barred by catalyst deactivation. (C) 2001 Els evier Science B.V. All rights reserved.