Other Intensification Strategies

This is in line with the strategy of process intensification and it is expected to bring substantial improvements in chemical and many other manufacturing and processing industries. 

Vanadium phosphates have been established as selective hydrocarbon oxidation catalysts for more than 40 years. Their primary use commercially has been in the production of maleic anhydride (MA) from n-butane. During this period, improvements in the yield of MA have been sought. Strategies to achieve these improvements have included the addition of secondary metal ions to the catalyst, optimization of the catalyst precursor formation, and intensification of the selective oxidation process through improved reactor technology. The mechanism of the reaction continues to be an active subject of research, and the role of the bulk catalyst structure and an amorphous surface layer are considered here with respect to the various V-P-O phases present. The active site of the catalyst is considered to consist of V and V couples, and their respective incidence and roles are examined in detail here. The complex and extensive nature of the oxidation, which for butane oxidation to MA is a 14-electron transfer process, is of broad importance, particularly in view of the applications of vanadium phosphate catalysts to other processes. A perspective on the future use of vanadium phosphate catalysts is included in this review. 

There are other possible unsteady (periodic) operation modes for a packed bed reactor that could lead to process intensification [57]. Indeed, there are several unsteady state strategies available to run a process unit such as a reactor. Pulses of different magnitude can be imposed on an input, or the input could be either changed progressively or varied according to an analytical function. However, not all unsteady state strategies are feasible in a commercial situation. Table 3.2 gives examples of the possibilities. 

The last chapter gives a more comprehensive approach and discusses the role of membrane gas separation and membrane engineering in the re-designing of industrial applications in terms of new, recently introduced metrics. It provides an analysis of some processes for hydrogen production/separation that can be easily extended in other separation processes. This is a useful tool for the evaluation of pros and cons during the design phase of a new plant, where the membrane operations would replace traditional ones to pursue the strategy of process intensification. 

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