Jorge Pena Lopez, Chemical Engineering Department, University of California at Los Angeles, 5531 Boelter Hall, Los Angeles, CA 90095 and Vasilios I. Manousiouthakis, Chemical Engineering Department, UCLA,, 5531 Boelter Hall, Los Angeles, CA 90095-1592.
The use of fossil fuels as a transportation energy source has driven large metropolitan areas around the world towards a deplorable air quality state. This urgent situation has motivated the development of technologies which aim to reduce the polluting emissions from automobiles. One viable option is the use of hydrogen as fuel, using hydrogen fuel cells to generate the energy in vehicles. Several options exist for hydrogen production; one of the most explored has been the reforming of natural gas given that methane contains potentially two hydrogen gas molecules. The main problem with conventional natural gas reformers is the emission of carbon dioxide, a greenhouse whose emissions have led to an increase in its concentration in the atmosphere. Transforming carbon dioxide into a useful product prevents its emission into the atmosphere, however an inadequate process design might largely increase the price of hydrogen with respect to gasoline, making it non-competitive.
In this work we present a hydrogen production process in which hydrogen and methanol are co-generated, while no carbon dioxide is emitted. Water and natural gas are fed simultaneously with oxygen in a partial oxidation reactor. The oxygen is separated from air in a pressure swing absorber process. The gases coming from the partial oxidation reactor are dried and mixed together and sent into a reverse shift-gas reactor to produce syngas that is then used in the production of methanol. In order to address and fulfill the energy requirements of the entire plant, heat and power integration techniques are applied into the process allowing us to maintain a self-powered process plant, reducing the carbon emissions to near zero and being economically feasible. We also show that there is an optimal operational and thermodynamical point for hydrogen production and power generation, and that on an operating cost basis, the proposed process is superior to that of the traditional steam reforming process.
Keywords: Hydrogen, Methanol, Partial oxidation, carbon dioxide