Other Units and Complex Processes

We now move onto a few so-called higher order or complex processes. We should remind ourselves that all linearized higher order systems can be broken down into simple first and second order units. Other so-called "complex" processes like two interacting tanks are just another math problem in coupled differential equations these problems are still linear. The following sections serve to underscore these points. 

Superffex C t lytic Crocking. A new process called Superflex is being commercialized to produce predorninantiy propylene and butylenes from low valued hydrocarbon streams from an olefins complex (74). In this process, raffinates (from the aromatics recovery unit and the B—B stream after the recovery of isobutylene) and pyrolysis gasoline (after the removal of the C —Cg aromatics fraction) are catalyticaHy cracked to produce propylene, isobutylene, and a cmde C —Cg aromatics fraction. AH other by-products are recycled to extinction. 

The biosynthesis of polyketides (including chain initiation, elongation, and termination processes) is catalyzed by large multi-enzyme complexes called polyketide synthases (PKSs). The polyketides are synthesized from starter units such as acetyl-CoA, propionyl-CoA, and other acyl-CoA units. Extender units such as malonyl-CoA and methylmalonyl-CoA are repetitively added via a decarboxylative process to a growing carbon chain. Ultimately, the polyketide chain is released from the PKS by cleavage of the thioester, usually accompanied by chain cyclization [49]. 

Some of the types of equilibria involved in the unit operations separation and concentration are listed in the introduction, Section 9.17.1. Those which depend most on coordination chemistry, and for which details of metal complex formation are best understood, are associated with hydrometallurgy. Once the metal values have been transferred to an aqueous solution, the separation from other metals and concentration can be achieved by one of the following processes.3... 

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