Zero emissions of CO2 during the production of liquid fuel from coal and natural gas by combining Fischer-Tropsch synthesis with catalytic dehydrogenation

Synthesis gas (syngas) produced by coal gasification typically has H-2/CO molar ratios in the range of 0.5-1.0. Fischer-Tropsch synthesis (FTS) of liquid fuels requires syngas with H-2/CO >= 2.0. Traditionally, this has achieved by the water-gas shift (WGS) reaction. In an earlier paper, it was shown that large reductions in CO2 emissions can be achieved by producing the required H-2 by catalytic dehydrogenation (CDH) of the gaseous (C1-C4) products of FTS, rather than by the WGS reaction. In addition to producing pure H-2, CDH converts the C in (C1-C4) gases into multi-walled carbon nanotubes (MWCNT), a valuable by-product. The current paper builds on this concept. It is shown that zero emissions of CO2 can be achieved by the FTS-CDH process if methane derived from natural gas is injected into the CDH reactor in appropriate amounts. (C) 2013 Elsevier Ltd. All rights reserved.