Abstract:
This report summarizes the second year research output of the project “Direct Synthesis of Isobutene from CO Hydrogenation with Zirconium dioxide Catalysts”. In the first year work, the catalytic performance on isosynthesis and characterization of different micron- and nanoscale zirconia catalysts were carried out and compared with those of ceria. In addition, the effect of temperature ramp during calcination of zirconia on characteristics of nanoscale zirconia catalysts and their catalytic performance for isosynthesis was investigated. In this second year work, the catalytic performance of zirconia catalysts with various content of sulfur on isosynthesis were studied. The characteristics of the catalysts were determined by using various techniques including BET surface area, XRD,NH3- and CO2-TPD, and SEM. For zirconia catalysts, it was found that zirconia catalysts synthesized from zirconyl nitrate showed the highest activity and selectivity of isobutene
in hydrocarbons among other ones. The acid-base properties and phase composition of sulfated zirconia influenced the catalytic performance. Moreover, the catalysts were improved by sulfur loading. It revealed that sulfated zirconia catalysts exhibited higher selectivity of isobutene in hydrocarbons than zirconia due to difference in acid-base properties, specific surface area and phase composition. Effect of calcination temperature was also investigated. For the commercial sulfated zirconia, it found that increased calcination temperature resulted in increased monoclinic phase in sulfated zirconia, but decreased acid sites. The result revealed that lower selectivity of isobutene in hydrocarbons. The 0.75% sulfated zirconia synthesized from zirconyl nitrate showed the major factor determining the activity and selectivity of isobutene in term of phase composition. Therefore, it was concluded that the difference in the calcination temperatures influenced the catalytic performance, sulfur content, specific surface area, phase composition and acid-base properties of the catalysts. In addition, the suitable reaction temperature for isosynthesis was 400 ํC.
