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2 PROCESS & TECHNOLOGY

FOR METHANOL & DME

ith the growth and demand for both methanol and DME as alternate fuel, the
conventional wood distillation process was not able to cope up with the enhanced
Wdemand. BASF was the first to acquire a patent on production of synthetic methanol
via syngas (synthesis gas). The first plant was started in 1923. This established the main
production route for both methanol and DME, which is still being followed today. The current
production of methanol is largely based on fossil sources with only between 1% and 2% of
the total methanol being produced from biomass. The carbon footprint for methanol/DME is
no better than that of fossil based transportation fuels. This is because the syngas is usually
produced from fossil fuels, either natural gas or coal. With the increasing concern about GHG
emission from transportation fuels, alternative sources of hydrocarbon feedstocks became
important. This includes wood, solid waste, biomass and other renewable resources.

The present emphasis is to produce bio methanol because all the benefits of using methanol/
DME as fuel will only be realized when they are produced from non-fossil sources. The
environmental benefits surpass the higher cost of production of methanol using biomass in
place of natural gas.

Regarding technologies for production of methanol, the established process uses syngas
produced from fossil fuel sources, while there are many technological challenges. Presently,
intense research activities are directed towards the area of biomass gasification. Several
demonstration plants are operating around the world. However, only a few plants are operating
as full commercial ventures.
The simplest way to produce DME is dehydration of methanol. The possibility of using DME as
direct substitute or as blending component for diesel was realized during the last decade of the
20th Century. DME is intimately related to methanol since it is the dehydrated form. In addition
to the simple dehydration of methanol, it could also be directly produced from syngas in a
single step, thereby avoiding the formation of methanol as intermediate. The issues regarding
fossil fuel or biomass as the feedstock for syngas production hold good for DME as well.
The current focus is towards the production of methanol/DME via syngas from advantageous
feedstocks such as low grade coal and solid waste (fossil or biomass), which are otherwise
burnt or incinerated, and from by-products of different industries such as steel plants, cement
plants or refineries.

The most common route for production of both methanol and DME is via syngas although
there are numerous available sources of feedstock for syngas production. The traditional route
for methanol and DME production could be summarized as:
Carbon Source + oxygen (or air) → Syngas (CO + hydrogen) → methanol → DME + water
In addition to the wide variety of fossil and non-fossil based feedstocks for syngas production,
there are variations in the types of gasifiers for conversion of carbon source to syngas as well
as for further transformation to methanol/DME.

26 Methanol and DME Production: Survey and Roadmap | 2017