Membrane reactors hydrogen production

Many excellent reviews on Pd-based membranes, membrane reactors and applications exist. Our intention is to give the reader insight about the status and to pin-point some trends and main challenges related to Pd-based membranes for hydrogen production. 

Table 27.2. Membrane reactors using dense ceramic membranes for hydrogen production.

Figure 7.4 shows the structure of an FBMR with plate-type Pd-Ag dense metal membranes for hydrogen production [8, 9]. Two-sided planar membrane panels are suspended vertically in the reactor. Each side of the panels consists of 25 pm thick Pd-Ag foil mounted on a porous stainless steel base with a barrier layer to prevent interdiffusion... 

Rnacci R, Brogha M. and Drago E, Development of Rd-composite membranes for hydrogen production in membrane reactors, Proc. of EFC 2011, Rome (I), December 14-16,2011. 

As an example the use of ceramic membranes for ethane dehydrogenation has been discussed (91). The constmction of a commercial reactor, however, is difficult, and a sweep gas is requited to shift the product composition away from equiUbrium values. The achievable conversion also depends on the permeabihty of the membrane. Figure 7 shows the equiUbrium conversion and the conversion that can be obtained from a membrane reactor by selectively removing 80% of the hydrogen produced. Another way to use membranes is only for separation and not for reaction. In this method, a conventional, multiple, fixed-bed catalytic reactor is used for the dehydrogenation. After each bed, the hydrogen is partially separated using membranes to shift the equihbrium. Since separation is independent of reaction, reaction temperature can be optimized for superior performance. Both concepts have been proven in bench-scale units, but are yet to be demonstrated in commercial reactors. 

Barbiery, G. et al., Hydrogen production using membrane reactor, Korean Membrane., 5,68,2003. 

Ishihara, T. et al., Decomposition of methane over Ni/Si02 catalysts with membrane reactor for the production of hydrogen, Chem. Lett., 93, 1995. 

Steam methane reforming with membrane WGS reactor for hydrogen production. 

Lin, J.Y.S., Zeolite Membrane Reactor for Water-Gas-Shift Reaction for Hydrogen Production, Proceedings of2007 U.S. DOE Hydrogen Annual Merit Review Meeting, Arlington, VA, May 2007. 

Lin, Y.M. and M.H. Rei, Study on the hydrogen production from methanol steam reforming in supported palladium membrane reactor, Catal. Today, 67, 77-84, 2001b. 

Pex, P.P.A.C. and Y.C. van Delft, Silica membranes for hydrogen fuel production by membrane water gas shift reaction and development of a mathematical model for a membrane reactor, in Carbon Dioxide Capture for Storage in Deep Geologic Formations—Results from the C02 Capture Project Capture and Separation of Carbon Dioxide from Combustion Sources, eds., D. Thomas, and B. Sally, Vol. 1, Chapter 17, 2005. 

Below, we first briefly describe conventional hydrogen production. Then the combination of hydrogen production and CCS is described. Finally, we elaborate on two of the technologies for more efficient hydrogen production with C02 capture that are currently in the R D phase hydrogen membrane reactors and C02 sorption enhanced reactors. 

For combined hydrogen production and C02 capture several novel technologies are in development, most of them for the application in a pre-combustion C02 capture combined cycle. The main focus is to reduce the efficiency penalties and other associated costs of CO2 capture. The most important technologies in the R D phase, membrane reactors and sorption-enhanced reactors, are described below, with special attention paid to the catalytic aspects. 

J.W. Dijkstra, Y.C. van Delft, D. Jansen, P.P.A.C. Pex, Development of a hydrogen membrane reactor for power production with pre-combustion decarbonisation, Proceedings of the 8th International... 

For a packed-bed membrane reactor (PBMR) the membrane is permselective and removes the product as it is formed, forcing the reaction to the right. In this case, the membrane is not active and a conventional catalyst is used. Tavolaro et al. [45] demonstrated this concept in their work on CO2 hydrogenation to methanol using a LTA zeolite membrane. The tubular membrane was packed with bimetallic Cu/ZnO where CO2 and H2 react to form EtOH and H2O. These condensable products were removed by LTA membrane which increased the reaction yield when compared to a conventional packed bed reactor operating under the same conditions [45]. 

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