Synthesis of gasoline fractions from CO and H2 through oxygenates

Abstract

The technology for the manufacturing of gasoline fractions (synthetic hydrocarbons) from synthesis gas (syngas) on zeolites through the oxygenate production step as developed at the Topchiev Institute of Petrochemical Synthesis, differs from the classical MTG process of ExxonMobil in that the oxygenate and gasoline production steps are integrated in one circuit. In the new technology, the synthetic hydrocarbons contain 6 to 27 wt % aromatic hydrocarbons (benzene and durene ≤2 wt %) depending on the H2/CO ratio in syngas. When syngas with H2/CO ≤ 3.5 in the vapor-gas mixture arriving at the gasoline production stage is used, an increased methanol (MeOH) content is observed and the MeOH conversion is incomplete with the exhaustive conversion of dimethyl ether (DME). To increase the involvement of MeOH in the synthesis of the gasoline fraction, the influence of various parameters on the conversion of MeOH and DME has been studied. It has been shown that a change in the composition of fresh syngas has a more significant effect notably on the MeOH, rather than the DME conversion into synthetic hydrocarbons and is enhanced with an increase in the MeOH weight hourly space velocity (WHSV). If the vapor-gas mixture arriving from the oxygenate production reactor at the step of production of the gasoline fraction contains more than 50 wt % MeOH, in order to improve the selectivity for the gasoline fraction, the synthesis should be conducted at a lower WHSV of oxygenates than in the case when the vapor-gas mixture contains DME alone.