CATALYSTS
Figure 1 - Conventional methane steam-reforming process ( left ) & sorption-enhanced reforming process ( right ) for hydrogen production with CO 2 capture
Figure 2 - Fluidisable nickel-based catalyst C & CS # 1050 of grain size fraction 0.1-0.25 mm ( left ) & picture of the surface of a catalyst grain recorded by scanning electron microscopy ( right )
For further process intensification , PSA , as the usual purification method for H 2
-enriched syngas , can be substituted by palladium membranes integrated in the reformer . 3 Thus , by separating pure hydrogen through these membranes from equilibrium reaction 4 , SER is also membrane-assisted .
For a continuous SER process operated in a fluidised bed reactor system , the mixture of reforming catalyst and CO 2 sorbent is transferred to the regenerator to desorb CO 2 at a higher temperature typical for the calcination of limestone ( 850-900 ° C ), after which the catalyst-sorbent mixture is returned back to the reformer in a solids circulation loop ( Figure 1 ).
The desorbed , highly concentrated
CO 2 from the regenerator can be used as feedstock for further processing to chemicals , further cleaned up for use in the beverage industry or stored permanently in geological formations .
Novel steamreforming catalyst
As no fluidisable reforming catalysts are commercially available for the SER process , however , a novel catalyst with suitable chemical and mechanical stability had to be developed in the MEMBER project . C & CS therefore developed a novel fluidisable steam-reforming catalyst , C & CS # 1050 . This complies with the requirements of a SER process in a fluidised bed environment :
• Efficient methane conversion at a relatively low temperature ( 600 ° C )
• High chemical and thermal stability at a high regeneration temperature in the presence of steam ( 850 ° C ), and
• High attrition resistance ( Figure 2 ) Attaining all these in the same catalyst is challenging . To achieve this , C & CS followed and patented a novel bottom-up approach by applying a chemical modification process of suitable precursors to produce a support material of high surface area , followed by an adapted incipient wetness impregnation process for the catalytically active metal . 4
C & CS # 1050 is based on a novel
MgO-Al 2
O 3 support material and shows a BET surface area more than five times higher than a CaAl 2
O 4
- supported nickel catalyst using a commercially available calcium aluminate support ( Figure 3 ).
Additionally , for comparison , C & CS # 1050 shows a 3.5 to four times higher specific surface area than commercial steam-reforming catalysts . 5 As a result , more than 70-140 % higher methane conversion in conventional steam-reforming is possible with it than with a commercial steamreforming catalyst .
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