화학공학소재연구정보센터
Industrial & Engineering Chemistry Research, Vol.58, No.40, 18731-18741, 2019
Spatially Patterned Catalytic Reactor for Steam-CO2 Reforming of Methane
Steam methane reforming has been extensively used in producing syngas, but the H-2/CO ratio of the syngas produced by the method is too large to feed to subsequent processes such as the Fischer-Tropsch process. The dry methane reforming process produces a syngas with a small H-2/CO ratio. Combining these two processes makes it possible to adjust the H-2/CO ratio to provide a syngas with a proper ratio for subsequent processes. Dry reforming is well-known to suffer a severe coke generation problem. If the two reactions occur simultaneously in one reactor, the coke generation problem can be greatly reduced by the presence of water in the reactor. However, this setup needs a catalyst suitable for both reactions in terms of both stability and performance, and no commercial catalyst has been reported to do this job. We propose a novel spatially patterned catalytic reactor in which two different catalysts, one suitable for steam reforming and the other suitable for dry reforming, are spatially layered. The catalysts and inert material are spatially layered, and the temperature of each catalyst layer can be maintained within the range of temperatures suitable for the corresponding reaction of the layer. The proposed method is shown to be able to provide syngas with a desired ratio while mitigating the coke generation problem. The optimization problem, which minimizes the length of the reactor, is formulated to provide an optimum temperature profile for the reactor. The two catalyst and inert layers are arranged along the length of the reactor to realize the temperature profile. The optimization results show that the amounts of catalysts and the capital and energy costs are greatly reduced compared with those of the conventional combined reforming process. The proposed reactor is also shown to maintain stable operation with large changes in feed flow rate and H-2/CO ratio by adjusting the fuel flow rate to maintain the reactor outlet temperature.