(33c) Direct Dimethyether Synthesis Using Revese Shift Assisted Reforming

DME has been attentioned as a fuel in Asia region. Although a direct DME synthesis process from synthesis gas seems to be attractive in the thermodynamic point of view, a lot of CO2 production results in the loss of a overall DME yield in stoichiometric point of view. On the other hand, since the direct DME synthesis can be optimized at about 1 of H2/CO ratio, the refoming of methane has been an important issue to ajust the H2/CO ratio to about 1. In our direct DME process, the conventinal steam reforming is used. The synthesis gas with the excess hydrogen from the steam reformer is separated to adjust the H2/CO ratios of the DME feed gas by a hydrogen membrane. The separated hydrogen is used to convert CO2 to CO on the reverse shift reaction, and then the enriched CO gas is recycled and combined with the synthesis gas from the reformer. CO2 source would be the additional one or the recovered one from the DME reactor. This process can increase the overall DME yield by mitigating CO2. The bench plant of this DME process was intalled and operated to show the high yield and low CO2 production in the direct DME synthesis, as compared with the conventional direct DME process.