OP-II-3

OP-III-A-12SELECTIVE CATALYTIC DEOXYGENATION OF FATTY ACIDS ANDTHEIR DERIVATIVES; CATALYST DEACTIVATION, REACTORSELECTION AND MODELLINGPäivi Mäki-Arvela, Teuvo Kilpiö, Tapio Salmi, Dmitry Yu. MurzinProcess Chemistry Centre, Åbo Akademi University, FI-20500 Turku, FinlandSelective catalytic deoxygenation of fatty acids and their derivatives has beendemonstrated over Pd/C and Pt/C catalysts. In case of stearic acid as a substrate,the main liquid phase product was n-heptadecane but small amounts of n-heptadecene were formed. The deoxygenation of the corresponding ester, ethylstearate proceeded via formation of stearic acid as an intermediate. CO and CO 2were the main gaseous products in both cases. These gaseous products couldpartially deactivate the catalyst and thus the selection of the reactor type is of crucialimportance in prolonging the catalyst life time. Furthermore, for the industrialapplications, the continuous operation is a more attractive one, compared to thebatch mode. The aim of this work was to compare the effect of different reactor typesin catalytic deoxygenation of fatty acids and their derivatives. For this purpose batch,semibatch as well as two types of continuous reactors were applied.Catalytic deoxygenation was performed in a temperature range of 270°C to360°C under 6 – 17.5 bar total pressure either under Ar or 1 – 5 vol% H 2 in Ar. Bothmicroporous active carbon as well as mesoporous synthetic carbon, Sibunit, wereused as catalyst supports for Pd with the loading varying from 1 wt.% up to 5 wt%.The batch reactor was operated typically using 1 g of catalyst and varying the initalconcentration of fatty acid (or ester) from 0.16 mol/l to 1.6 mol/l in dodecane. Dilutedstreams as well as neat stearic acid were used as a feedstock for the continuousreactor. When the same reactor was used in semibatch mode, the gas phase wasflowing through the reactor. Furthermore, two types of fixed bed reactors wereapplied in this work, namely a fixed bed upflow reactor in the absence of flowingcarrier gas as well as a downflow reactor together with a cocurrent gas flow.The results revealed that the batch reactor gave lower conversions of ethylstearate than achieved in the semibatch reactor (Fig. 1a). This result can beexplained by the fact that the CO formed can be continuously purged from thecatalyst surface with the aid of the carrier gas flow in the semibatch reactor.173