Aspects of Mechanisms, Processes, and Requirements for Zeolite Separation

Aspects of Mechanisms, Processes, and Requirements for Zeolite Separation 

As documented in Chapter 5, zeolites are very powerful adsorbents used to separate many products from industrial process steams. In many cases, adsorption is the only separation tool when other conventional separation techniques such as distillation, extraction, membranes, crystallization and absorption are not applicable. For example, adsorption is the only process that can separate a mixture of C10-C14 olefins from a mixture of C10-C14 hydrocarbons. It has also been found that in certain processes, adsorption has many technological and economical advantages over conventional processes. This was seen, for example, when the separation of m-xylene from other Cg-aromatics by the HF-BF3 extraction process was replaced by adsorption using the UOP MX Sorbex process. Although zeolite separations have many advantages, there are some disadvantages such as complexity in the separation chemistry and the need to recover and recycle desorbents. 

This chapter addresses the fundamentals of zeolite separation, starting with (i) impacts of adsorptive separation, a description of liquid phase adsorption, (ii) tools for adsorption development such as isotherms, pulse and breakthrough tests and (iii) requirements for appropriate zeolite characteristics in adsorption. Finally, speculative adsorption mechanisms are discussed. It is the author s intention that this chapter functions as a bridge to connect the readers to Chapters 7 and 8, Liquid Industrial Aromatics Adsorptive Separation and Liquid Industrial Non-Aromatics Adsorptive Separation, respectively. The industrial mode of operation, the UOP Sorbex technology, is described in Chapters 7 and 8. 

Impacts of Adsorptive Separation Versus Other Separation Processes 

Separation processes play a significant role in industry. These processes include distillation, absorption, extraction, adsorption, crystallization and membrane sepa- 

---

I 6 Aspects of Mechanisms, Processes, and Requirements for Zeolite Separation Table 6.2 Analysis of citric acid product by adsorption. 

---