Selective formation of isobutene from CO hydrogenation over zirconium dioxide based catalysts

Zirconium dioxide based catalysts were prepared by mechanical mixing method and evaluated in the direct synthesis of isobutene and isobutane (i-C-4) f rom CO hydrogenation. The acid and base properties of the catalysts were al tered by varying the content of additives (Al2O3, KOH) on ZrO2. Al2O3-KOH s howed to be effective promoters that could remarkably enhance the i-C-4 sel ectivity in total hydrocarbons while maintaining high activity. A CO conver sion of 30% was achieved at 698 K, 5.0 MPa, 1/1 CO/H-2 ratio, and 650 h(-1) space time over 23.7%Al2O3-0.5%KOH-ZrO2. Meanwhile, the i-C4 selectivity i n total hydrocarbons was about 62%. The performance of the catalysts depend ed on the acid-base properties of the catalysts, and the appropriate amount of acid and base and the ratio of the base to acid sites are significant f or an isosynthesis catalyst to selectively produce isobutene and isobutane from CO hydrogenation.