Cycloversion

Cycloversion A petroleum treatment process which combined catalytic reforming with hydrodesulfurization. The catalyst was bauxite. The process differed from the Houdry process in that the catalyst bed temperature was controlled by injecting an inert gas. Developed by the Phillips Petroleum Company and used in the United States in the 1940s. Pet. Refin., 1960, 39(9), 205. 

Another fixed-bed process, announced by Phillips Petroleum Company in 1944, was the Cycloversion process which employed bauxite as catalyst (83,285). 

Commercial fixed-bed catalytic cracking includes the Houdry process and the Cycloversion process. Of the two, the Houdry process has been much more widely used. 

Flo. 9. Flow diagram of Cycloversion catalytic cracking unit. [Buell and Skinner, Oil Oas J. 43, No. 52, 87 (1945). Reprinted by permission.]... 

A Cycloversion plant consists basically of a preheater and at least two reactors, in order to permit continuous operation. A flow diagram is... 

The Houdry, TCC, Houdriflow, and Cycloversion processes use catalysts in the form of particles several millimeters in diameter. The fluid process employs catalyst in the form of fine particles smaller than grains of sand. 

The catalyst employed in the Cycloversion process is a selected grade of naturally occurring bauxite (161) in the form of irregular lumps. 

Catalyst-manufacturing methods can be classified into two broad categories. In one, a naturally occurring solid material is treated to alter its physical or chemical properties. The treated solids are sometimes referred to as natural catalysts. These include the Filtrol activated clays and the bauxite Cycloversion catalyst. In the other category of methods, the solid catalyst is produced synthetically by interaction of aqueous solutions of the raw materials. 

While natural or activated clay catalysts are no longer employed in the fixed-bed Houdry process, they are still widely used in the fluid process and to a considerable extent in the TCC process. A natural bauxite catalyst is employed in the fixed-bed cycloversion process, developed by the Phillips Petroleum Company. This process is of greater importance as a naphtha reforming process than as a catalytic cracking process. 

Fixed-bed Houdry and Cycloversion catalytic cracking, platinum catalyst reforming, the original Hydroforming installations, and the desulfurization processes are examples. 

Fig. 21-1. Basic ways of handling catalysts, (a) Fluidized catalyst (6) airlift (T.C.C. and Houdriflow) (c) fixed bed (Houdry and Cycloversion) and (d) suspended in oil (Suspensoid).

Percentage conversion Cycloversion Fluid Houdry Moving-bed... 

Octane number is probably affected more by the reaction temperature than by any other variable. The trend of octane number is indicated in Table 21-5 for a fixed percentage conversion. Similar data are. given for the Fluid process alone by Murphree and associates, f and for the T.C.C. process alone by Noll and associates. Table 21-5 does not apply directly to Cycloversion, Suspensoid, or Hydroforming operations, but the general trend is the same. 

The effect of percentage converaion on yields has already been mentioned under the heading of Yields. In addition, octane numbers are higher by one or two units when raising the once-through conversion from 55 to 65 per cent. Schulze and Helmars discuss the effect of percentage conversion on the Cycloversion process. 

Buell and Waddill, Cycloversion Process, PeL Refiner, October, 1944, p. 83. 

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