II International Symposium on Carbon for Catalysis ABSTRACTS

OP-<strong>II</strong>-11
ACTIVATED CARBON-TUNGSTOPHOSPHORIC ACID CATALYSTS FOR THE
SYNTHESIS OF TERT-AMYL ETHYL ETHER
Obali Z., Dogu T.
Department of Chemical Engineering, Middle East Technical University, Ankara, Turkey
e-mail: tdogu@metu.edu.tr
Due to the water pollution problems created by MTBE, ethanol based oxygenates atracted
the attention of number of researchers and fuel producers as octane improving gasoline
additives [1]. Such gasoline blending oxygenates also cause significant reduction in the
exhaust emmissions of CO and unburned hydrocarbons.Tert-amyl ethyl ether (TAEE), which
can be synthesized by the reaction of ethanol with isoamylenes, 2M2B (2-methyl-2 butene) or
2M1B (2-metyl-1 butene), over acidic catalysts is one of these oxygenates [2,3]. C 5 reactive
iso-olefins (2M2B and 2M1B), which are available in light gasoline, may be reacted with bioethanol
in fixed bed reactors or in a reactive distillation column to produce TAEE [4,5].
Heteropolyacid catalysts are excellent candidates to be used in the synthesis of TAEE.
Originally these catalysts have rather low surface area values, being in the order of magnitude
of a few m 2 /g. The catalysts prepared by loading the heteropolyacid catalysts on the pore
surfaces of high surface area activated carbons are expected to show higher activity and
stability than pure heteropolyacid catalysts. In the present study, activated carbontungstophosphoric
acid (TPA) (H 3 PW 12 O 40 .xH 2 O) catalysts were prepared and tested in the
TAEE synthesis reaction. The effects of reaction temperature and the loading level of
tungstophosphoric acid on the activity of these catalysts were investigated in the etherification
reaction.
The loading of TPA into the activated carbon was achieved following an impregnation
procedure by using the solutions of TPA in water and in ethanol. Before the impregnation
step, the activated carbon (with an average particle size of 0.036 cm) was washed by acidic
solutions. The impregnated particles were then dried and calcined at either 120 o C or 180 o C.
These temperatures were decided from the TGA analysis of the catalysts, which indicated two
peaks of weight losses before 120 o C and at 170 o C, due to the removal of water. A third wide
peak of weight loss together with sintering of the catalyst was observed over 230 o C. The
surface area of the acid treated activated carbon was decreased from 884 m 2 /g to 501 m 2 /g, as
114