Investigation the activity and long term durability of a Bi-functional catalyst in direct DME Synthesis

Direct synthesis of dimethyl ether was conducted in a mechanically agitated slurry reactor system at different temperature and H2/CO molar ratio of feed for 60 h time on stream (TOS) in order to confirm the high activity and long term stability of a bi-functional catalytic system (CuO-ZnO-Al2O3/H-MFI-90). Statistical experimental design was applied for determining the optimum operating conditions under which the catalytic system shows the highest performance. A significant improvement in the performance of the bi-functional catalyst observed when the temperature and H2/CO molar ratio of feed were increased form 200 to 240 o C and 1 to 2 respectively at a constant pressure 35 bar and GHSV equal to 1100 mLn/g-cat/hr. CO conversion was increased from 9.1 mol. % at T=200 o C and H2/CO=1 to 79.6 mol. % at T=240 o C and H2/CO=2 and the yield and selectivity of DME also increased from 7.11% to 47.05% and 41.57% to 59.96% (molar basis) respectively. No significant deactivation has been observed during 60h TOS at different operating conditions. Furthermore, from the main effect plots and response table results, it was concluded that the most effective factor on activity and stability of Bi-functional catalytic system is temperature.

Keywords:

Bi-functional Catalyst , Dimethyl ether , Experimental Design , Stability