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 H2/CO molar ratios in the range of 0.5–1.0. Fischer–Tropsch synthesis (FTS) of liquid fuels requires syngas with H2/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 H2 by catalytic dehydrogenation (CDH) of the gaseous (C1–C4) products of FTS, rather than by the WGS reaction. In addition to producing pure H2, 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.