Abstract:
The purpose of this research is to modify copper-based catalysts with HZSM5
compared to potassium-modified HZSM5 for dimethyl ether synthesis via CO2 hydrogenation.
The catalysts were prepared by simple impregnation method without calcination. Thermodynamic
analysis was carried out to optimize conditions of carbon dioxide hydrogenation and the results
were compared with experimental results. The catalysts were characterized by means of BET
technique, X-ray diffractometer, NH3
-TPD (NH3 Temperature programmed desorption) and CO2
-
TPD (CO2 Temperature programmed desorption). The results of thermodynamic analysis under
pressure 1to 10 bar, temperature ranging from 100 to 500o
C and at CO2
: H2
ratio 1 : 2, 1 : 3 and
1 : 4 revealed that %CO2
conversion to methanol or dimethyl ether was the highest at 100 o
C
under 10 bar and molar ratio of CO2
: H2
ratio at 1 : 4. The CuZn/ZrO2
catalyst after reduction 8 h
exhibitedthe highest methanol synthesis (12.6 g/kgcath) at 210o
C 10 bar and CO2
: H2
ratio 1 : 4.
The CuZn/ZrO2+K-HZSM5catalyst gave the highest dimethyl ether synthesis at 44.68g/kgcath
compared to CuZn/ZrO2+HZSM5 catalyst due to lower acid strength that modified by potassium
and it can retard cleavageof methanol or dimethyl ether to form hydrocarbon compounds.