83
November
2016
HYDROCARBON
ENGINEERING
S
everal industrial processes require aromatic
compounds, such as benzene, toluene, xylene
and cumene, or aliphatic compounds, such as
hexane, cyclohexane or heptane with low levels
of olefins, as raw materials. A very common process for
the removal of olefins is Friedels Crafts alkylation using
an aromatic or aliphatic molecule catalysed by an
acidic mineral catalyst to form alkylates, which can be
removed downstream through distillation in high
boilers. The alkylates do not contain the olefin double
bonds. Alkylation is an ongoing catalytic reaction on
acid sites, only terminated by catalyst poisons. The
acid sites deactivate during operation by poisoning,
which occurs when a reaction partner stays attached to
the acid site or does not donate back the hydrogen
atom utilised in alkylation. High boiling compounds
with a large carbon number can block active sites and
act as poisons. The alkylation is performed in fixed bed
operations at elevated temperatures in the range of
150 - 210˚C, and in a liquid phase. Mineral catalyst is
granular, with typical particle diameters in the
millimetre range.
Galp Energia faced the challenge of finding a long
lasting high capacity mineral catalyst, in order to
Jo
ā
o Amorim, Fernando Borges and Sérgio Moutinho, Galp Energia, Portugal,
and Lutz Kunze, Lothar Karrer and Bjorn Welander, BASF – Catalyst Division,
Germany,
describe how Galp Energia improved aromatic purification efficiency
through the use of high performance activated bentonite.
