After some intense research, scientists have finally
demonstrated the direct conversion of CO2 to methanol (CH3OH) using a homogenous catalyst.
The study was led by G.
K. Surya Prakash, a chemistry professor at the University of Southern
California, along with the Nobel laureate George A. Olah, a distinguished
professor at the University of Southern California. The researchers have
published their paper on the CO2 to methanol conversion process in a recent issue of the Journal
of the American Chemical Society.
"Direct
CO2 capture and conversion to methanol using molecular hydrogen in the
same pot was never achieved before," lead researcher G. K. Surya Prakash,
from the University of Southern California, told Phys.org. "We have now
done it!"
The major breakthrough
in the study was identifying the catalyst which speeds up the reaction and does
not degrade at high temperature required for the process. Majority of the
catalysts did not work beyond the formic acid stage. The catalyst, based on
metal ruthenium, is a homogenous catalyst, i.e, it is in the same phase as CO2
and hydrogen reacts with. Due to this fact, CO2 does not need
to be transformed after it is captured from the air and be simple added to
Hydrogen gas. The catalyst can function at high temperature (decomposes at 155⁰C) and does not lose
its efficiency. The catalyst can also reduce the carbamates or
alkylammonium bicarbonates directly to methanol.
The process:
Air is bubbled through an aqueous solution of pentaethylenehexamine (PEHA), which is
a polyamine and a catalyst is added to stimulate hydrogen
to latch onto CO2 (atmospheric- 400ppm) under pressure.
The solution
is heated at high temperature (≈150⁰C), and around 79% of CO2 is converted to methanol. Methanol at this
stage is mixed with water, which can be easily separated through simple distillation.
The reaction is as follows:
References:
http://www.rsc.org/chemistryworld/2016/01/fuel-air-carbon-dioxide-capture-methanol-renewable-energy
http://phys.org/news/2016-01-carbon-dioxide-captured-air-methanol.html
http://www.sciencealert.com/researchers-can-now-convert-captured-co2-directly-into-methanol-fuel
