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CURRENT STATUS OF TECHNOLOGY AND TRENDS

penalty. However, there are very few plants commercially operating for production of methanol/
DME. With the increasing interest in bio based liquid fuels, these biomass based combustion
units could be reengineered to produce methanol/DME. Since the feed pre-treatment and
combustion furnaces are already in position, it is required to modify the gasifier and post
treatment of the syngas, using available technologies.
The conventional methanol synthesis process from syngas requires CO free syngas, which
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means that carbon dioxide separation unit must be installed, before feeding to the conventional
methanol reactor. This adds up to a high cost burden on a medium size bio methanol plant.
Recently, several reports have been published where the methanol reactor is operated in
slurry phase rather than conventional low temperature high pressure gas phase. This slurry
route can handle a wide variety of syngas compositions as well as the presence of carbon
dioxide in the syngas. Therefore, there is also a possibility to do away with the conventional
shift reactor to adjust the H / CO ratio in the syngas produced from the gasifier. This new
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development will be very handy for small scale bio methanol plants. Air Products offers
such liquid phase technology. Ohio University reports a laboratory study on one-step liquid
phase DME synthesis using dual catalyst system at 1000 psi and 250 C with copper, zinc and
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aluminium based catalyst [35].
Carbon dioxide reforming is one of the viable routes to produce methanol/DME with negative
carbon footprint. A large number of publications are available in the literature that underlines
this point. Some amount of carbon dioxide could be recycled in the methane reformer, but
large scale utilization of carbon dioxide is of interest.

An exhaustive review was published in ‘Renewable and Sustainable Energy Reviews’ in
2014, in which the nature of different types of biomass and their processing strategy had been
discussed. Although the review was for power generation based on biomass, the information
is applicable to bio methanol plants as well [36].

3.4 Production Flexibility to Address Market Needs

At present there is a global surplus in methanol production capacity. The demand for methanol
for production of formaldehyde etc. is not growing. For a new dedicated plant for DME production
with assured demand, it is possible to convert syngas directly to DME in a single step. Due
to very low capital cost and natural gas price, this is the preferred feed for syngas production
in USA and Middle East. On the other hand, China and many other developing countries are
forced to use coal as the carbon source. The carbon penalty is obviously higher for coal based
methanol/DME plants.

It is projected that use of methanol and DME will increase many fold as transportation fuel,
mainly as liquid energy carrier. The focus on bio methanol will increase because this is a key
route for reduction of carbon footprint. For methanol produced from natural gas or coal, its
use as fuel offers marginal benefits in emission. However, carbon capture at the production
unit provides the opportunity to control carbon dioxide emission at the source itself; thereby
the GHG impact of the fuel is significantly reduced. With the recent stress on environmental
impact, large scale methanol plants based on coal or natural gas are designed for Integrated
Gasification Combined Cycle (IGCC) along with coproduction of methanol and chemicals. The
new units use oxygen rather than air as oxidizing medium and very often incorporate a carbon
separation and sequestering facility. This combination gives all the required flexibility, and most
of the associated technologies are matured.
It must be understood that the economics still favour the use of transportation fuels derived
from fossil hydrocarbon sources. Till now, all the possible alternative transportation fuels such

50 Methanol and DME Production: Survey and Roadmap | 2017