Regeneration Coking

The MTO process employs a turbulent fluid-bed reactor system and typical conversions exceed 99.9%. The coked catalyst is continuously withdrawn from the reactor and burned in a regenerator. Coke yield and catalyst circulation are an order of magnitude lower than in fluid catalytic cracking (FCC). The MTO process was first scaled up in a 0.64 m /d (4 bbl/d) pilot plant and a successfiil 15.9 m /d (100 bbl/d) demonstration plant was operated in Germany with U.S. and German government support. 

Particulate matter Boilers, catalyst regenerators, coking operations, heaters, incinerators... 

Fig. 3.3.11 Partially regenerated, coked Al203 catalyst samples with the same residual coke content of 7.65% left, regenerated at 550 °C right, regenerated at 400 °C. (a) Optical photographs of cut samples (b) NMR images with...

Octane Catalyst Ni + V Coke Yield Regenerator Coke Processed ... 

In the regenerator, coke deposited on the catalyst is partially burned to form carbon monoxide in order to reduce iron tetroxide and to act as a heat supply. In the desulfurizer, sulfur in the solid catalyst is removed and recovered as molten sulfur in the final recovery stage. 

As described by Gerritsen et al [23] in the Cyclic Deactivation method the catalyst is deactivated by several Reaction and Regeneration (coke burning) cycles. As we will discuss in the next section of this paper, this is essential for the realistic aging of the metals. 

The commonly practiced method of regenerating coked catalysts or catalytic membranes is by combustion with air, air/stcam mixtures, air/nitrogen mixtures, or dilute oxygen streams with another carrier gas. 

In commercial regenerations coke burning is started at low temperature and the process is controlled by the chemical step. This burning is similar to the TPO of coke shown in Figure 2. The coke deposited on the metal burns first and then, by increasing the temperature the most condensed coke deposited on the support is burnt. 

In the early 1970 s Mobil O//developed zeolite catalysts for the isomerization of xylene without the use of hydrogen (LTI method). This process is carried out in the liquid phase at a pressure of 30 bar and temperatures of from 200 to 260 °C. The service life of the catalyst is generally over 2 years. Regeneration (coke removal) is carried out from a reaction temperature of around 275 °C. 

Partly regenerated coked catalyst Details in Tang, Kern, and Jess, 2004. 

Depending on the type of regeneration (coke bum-off), reforming processes are classified into three types (i) semi-regenerative, (ii) cychc regenerative, and (iii) continuously regenerative. 

Nevertheless the recycling of the regenerated coke is as well possible if it leads to a cost advantage. 

The heat balance in an FCC rrrrit is corrrplex and depends on the combustion of coke in the regenerator. Coke formation on the catalyst must be carefuUy controlled when the feeds corttairrs residue, hrrprrrities such as orgartic rtickel, varta-dium corrtpotrrtds, and Cortradson carbon lead to increased coke deposihon artd this affects the rest of the rrrrit It is necessary to passivate the metals with additives arrd dilute or hydrotreat the residue. 

---