Research of Preparation of Liquid Hydrocarbons by Supercritical Fischer-Tropsch Synthesis On Bifunctional Catalyst Co/Zn/Mn/K/Ni/SO42-

Nano-catalysts (Co/Zn/Mn/K/Ni) and bifunctional nano-catalyst (Co/Zn/Mn/K/Ni/SO₄^2-) impregnated with 0.4 mol/L H₂SO₄ of Fischer-Tropsch synthesis have been prepared. Catalysts were investigated in a slurry-bed reactor under supercritical FTS conditions (T=240^oC,P=4.5MPa). Results show that the liquid hydrocarbons products selectivity and content of isoparaffin on Co/Zn/Mn/K/Ni/SO₄^2- catalyst were even higher than those of the Co/Zn/Mn/K/Ni catalyst. The highest selectivity of liquid hydrocarbons products (96.66% from 91.8%) and isoparaffin (72.19% from 40.57%) could be demonstrated over Co/Zn/Mn/K/Ni/SO₄^2- catalyst. In addition, the lower content of CH₄ (0.09% from 3.48%)and CO₂ (0.03% from 0.42%) could also be demonstrated over Co/Zn/Mn/K/Ni/SO₄^2- catalyst. The CH₄ as co-solvent adding amount to achieve a supercritical fluid were investigated. The result shows that CH₄ addition can enhance activity of catalyst, decrease the content of CH₄ and temperature, and increase the isomerization degree for a supercritical phase reaction. As the CH₄ pressure reaching 1.0MPa, for Co/Zn/Mn/K/Ni/SO₄^2- catalyst the conversion of CO increased from 88.45 to 98.29%, and isoparaffin products was 85.25%, content of CH₄ was 0.012%, while the temperature was 230^oC, respectively. It can be seen that the supercritical Fischer-Tropsch reaction with CH₄ as co-solvent over Co/Zn/Mn/K/Ni/SO₄^2- nano-catalyst was the best reaction process. It was beneficial to increase the production of isoparaffin, thereby increasing the quality level of the final production.