Reactor autothermal membrane reformer

Figure S.SS Configuration of a diesel fuel processor based upon an autothermal membrane reformer reactor [405].

Hydrocarbon Reforming 4 [HCR 4] Compact Membrane Reactor for Autothermal Methane Reforming... 

A possible approach Natural gas can be converted at a high temperature into hydrogen, CO, C02 (syngas) in a steam reformer or partial-oxidation reactor, or autothermal reformer which is a combination of the first two. Most of the CO in the syngas is typically converted into carbon dioxide at a lower temperature in a water-gas shift reactor. The remaining small amount of CO must be removed to below 10 ppm level. This can be done using adsorption, or membrane separation, or catalytic preferential oxidation (at about 90°C with an air stream), or other practical means. Also, there are designs with membrane reformers in the literature. 

Figure 11.4 Schematic representation of the two fluidized membrane reactor concepts for autothermal methane reforming with integrated CO2 capture (a) Methane combustion configuration (b) Hydrogen combustion configuration, after Patil et al.

Possible SMR-membrane reactor configurations (a) externally heated reformer (b) non-adiabatic membrane reformer and (c) autothermal reformer. 

A typical fluidized membrane reactor (or membrane-assisted fluidized bed reactor - MAFBR) consists in a bundle of permselective membranes immersed in a catalytic bed operated in a bubbling or turbulent fluidization regime. The use of fluidized bed membrane reactors not only makes possible the reduction of bed-to-wall mass transfer limitations, but also allows operating the reactor under virtually isothermal conditions (due to the movement of catalyst). This possibility can be used for operating the autothermal reforming of hydrocarbons inside the membrane reactor. In fact, as indicated by Tiemersma et al. [13], the autothermal reforming of methane in a packed bed membrane reactor is quite... 

Figure 9.11. Feed-side CO and C02 mole fraction profiles along the length of membrane reactor for autothermal reforming syngas. (Reprinted with permission from Huang et al.,6 Copyright 2005 Elsevier.)...

Further increases in methane conversion were attained by using an additional bed downstream from the membrane bed. In addition, the reactor temperature was increased so that the second bed operates at temperatures higher than the autothermal operation. This allows for the dry reforming reaction to occur in the second bed thus increasing the conversion of the methane not consumed in the first bed. In this case the highest methane conversion was about 90% with CO and H2 selectivities of about 90% when the external temperature is 700°C. Similar results can be attained without heating if a third feed of O2 is added between the membrane bed and just before the second fixed bed. In this case, the temperature increase is realized by the partial oxidation reaction with no major loss of selectivity. 

Elucidated the effects of system parameters on the membrane reactor for s5mthesis gases from steam reforming and autothermal reforming. 

We have developed a mathematical model for the countercurrent WGS membrane reactor with a CO2-selective membrane in the hollow-fiber configuration using air as the sweep gas. With this model, we have elucidated the effects of system parameters on the novel WGS membrane reactor for synthesis gases from steam reforming and autothermal reforming. The modeling results show that H2 enhancement via CO2 removal and CO reduction to 10 ppm or lower are achievable. For comparison and the completeness of the modeling work, we have also developed a similar model for the cocurrent WGS membrane reactor. 

Figure 2. Profiles of Carbon Monoxide Mole Fractions in the Hydrogen Products Along the Countercurrent Membrane Reactors for the Synthesis Gases With (1) 18.63% CO from Steam Reforming and (2) 5% CO from Autothermal Reforming...

Few studies are reported in literature dealing with the integration of an autothermal reforming reactor with a membrane for hydrogen separation, and most of them are simulation studies. 

The laboratory plant employed for the catalytic activity tests in the presence of a membrane integrated in the autothermal reforming reactor is reported in Fig. 6.1. 

Gallucci F, Van Sint Annaland M, Kuipers JAM (2008) Autothermal reforming of methane with integrated CO2 capture in a novel fluidized bed membrane reactor. Part 1 experimental demonstration. Top Catal 51 133-145... 

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