Analysis of the Steady-State Properties of a Bifunctional Catalyst for the Synthesis of Renewable Fuels

The chapter reports on the influence of the structure of a bifunctional catalyst pellet on the yield of dimethyl ether (DME) produced directly via methanol from synthesis gas. Theoretical studies were conducted with the aid of a mathematical model of a single isothermal porous bifunctional pellet integrating metallic catalyst for methanol synthesis and acidic catalyst for its dehydration into DME. Evaluation of the pellet performance was done for three arrangement of the catalytic active sites within the pellet, and for various volume fractions of the pellet occupied by each type of active sites. It was shown that, in case of relatively large pellets, a substantial enhancement in the DME yield can be obtained by using the core-shell structure with metallic catalyst located in the pellet core and acidic catalyst located in the pellet shell. Moreover, the proportions between the two catalysts within the pellet showed a marked influence on the DME yield calculated with respect to hydrogen.