The growing concerns about climate change and energy consumption have been the driving force in
seek of alternative fuels such as DME, mainly produced via methanol dehydration over a solid acid
catalyst. The use of activated carbons for this aim has been little studied up to date. Only a few studies
can be found in the literature, reporting all of them materials with a low thermal stability of the acid
surface groups, which results into a fast deactivation of the catalyst.
In this work, the preparation of activated carbons via chemical activation with phosphoric acid, their
modification with different ZrO2
loads, and their application as methanol dehydration catalysts have been
studied. The catalytic results showed that the best methanol conversion and selectivity towards DME
were achieved with the activated carbon prepared with an impregnation mass ratio value
(H3PO4
/precursor) of 2 and an activation temperature of 800 ºC, loaded with a 7 % (wt) of ZrO2
. This
catalyst exhibits high steady state methanol conversion values even at temperatures as high as 400 ºC
(XCH3OH= 80%, 0.1 g·s/μmol, PCH3OH= 0.08 atm in helium), keeping a selectivity to DME higher than
96%. The effect of oxygen in the reaction atmosphere was also analysed. In this sense, an increase of
15 % in the DME yield was obtained when using air instead of helium as reaction atmosphere (350 ºC,
0.1 g·s/μmol, PCH3OH= 0.04 atm).
A kinetic study has been carried out on this catalyst in which two mechanisms (Eley Rideal and Langmuir
Hinshelwood) for methanol dehydration have been analysed. The models proposed also consider the
presence of oxygen in the reaction media.
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