Abstract
The quality requirements of fuels have significantly increased in the last 20 years. Furthermore, the demand for fuels produced from non-edible plants or waste biomass has become more important, due to more stringent environmental protection and political regulations. Fuel blending components are also produced from synthesis gas by Fischer-Tropsch synthesis. The boiling point of the 40 - 45 % of Low-Temperature Fischer- Tropsch product is higher than 370 °C, so-called Fischer-Tropsch wax. The wax is less valuable commercially, thus it is appropriate to hydrocrack it to more valuable liquid hydrocarbons, having lower molecular weight. In case of hydrocracking hydroisomerization also take place. Isoparaffins have advantageous performance properties; they burn clean relative to aromatic hydrocarbons, and they are desirable components of fuels. In our experimental work we investigated the fuel purpose hydrocracking of high molecular weight Fischer- Tropsch wax on Pt/H-ZSM5, Pt/H-Beta and Pt/H-[BAl]MCM22 zeolite catalysts. The main properties of feedstock were the followings: carbon number range: C13-C69, C21+ hydrocarbon content: > 99 %, pour point: 84 °C. The main products were gases (10 - 48 %) and gasoline (10 - 60 %) on the tested catalysts. The C21- product – formed on Pt/H-Beta zeolite – contained 85 % isoparaffin hydrocarbon, while on the Pt/H-[BAl]MCM22 and Pt/H-ZSM5 zeolite took place isomerization in smaller degree (iso/n-paraffin ratio: 2 - 3 and 0.5 - 0.6, respectively). In our experiments we could produce fuel components – belonging to different boiling point range – with good yield and we observed shape selective effects and special selectivity as well, due to specific structural of zeolites.
