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INDIAN SCENARIO

4.5.1.3
CARBON DIOXIDE HYDROGENATION

Since this is another very promising route and India depends more on coal based power as
well as chemical production, this route of carbon fixation and chemical production will be very
attractive for India.
It is reported that India has about 10,000 MWe of geothermal power potential, but excluding
some direct use of the heat energy, no power plant is working with geothermal energy. Different
orogenic regions are – Himalayan geothermal province, Naga-Lushai geothermal province,
Andaman Nicobar Islands geothermal province and nonorogenic regions are – Cambay
graben, Son NarmadaTapi graben and few other locations [161]. For demonstration plant, one
of these locations could be chosen or other industrial source of hydrogen and carbon dioxide
could be selected. Technology could be outsourced or developed through pilot plant studies.

4.5.1.4

LIQUID PHASE DME PRODUCTION FROM SYNGAS
In this emerging process, the syngas is reacted in a slurry phase reactor in presence of
powdered catalyst. This reaction takes place at moderate temperature and pressure. The
most important feature is that unlike the conventional methanol reactor where the hydrogen to
carbon monoxide ratio has to be closer to 2 and tolerance of the carbon dioxide concentration
is low, this liquid phase process can handle H /CO ratio from 0.5 to 2 [41]. It is claimed that the
2
liquid phase one step DME synthesis can tolerate any amount of carbon dioxide with syngas.
Both these features and the simplicity of the synthesis process are most suitable for small
scale DME plants using available syngas, where not much needs to be done to adjust the H /
2
CO ratio or to remove the carbon dioxide, which is often an expensive step [91].
This route offers low pressure methanol production with less stringent limitation on syngas
composition as well as the hardware is simple. Only the novelty is in the catalyst formulation.
It may not be very difficult to develop a catalyst and technology, in near future.
In recent times this route is getting lot of attention particularly for biomass gasification and
syngas utilization. It is observed that biomass gasification and single step DME production is a
more economical solution than using the syngas for power production [92 & 93].
A simplified flow sheet of direct DME synthesis is shown in Fig. 8.

FIG: 11
Simplified Flow Sheet for Direct DME Synthesis [41]

Natural gas CO 2
Steam Purge gas
O 2 DME
Auto-thermal reformer DME synthesis Separation (purification)
Water
Water Methanol

Methanol and DME Production: Survey and Roadmap | 2017 75