Synthesis of LPG via DME from syngas in two-stage reaction system

Abstract

Synthesis of liquefied petroleum gas (LPG) via dimethyl ether (DME) from syngas was carried out in a two-stage reaction system, where syngas was transformed to DME in the first stage over the Cu–Zn–Al/ZSM-5 catalyst and then to hydrocarbons in the second stage over the Pd–Y catalyst. CO conversion and LPG selectivity were dominated by the first and second stage, respectively. CO conversion could be kept at a high level through the gradual increase of reaction temperature of the first stage, although there was a slight deactivation for the Cu–Zn–Al/ZSM-5 catalyst. LPG selectivity in hydrocarbons was more than 75% due to the proper pore size of Y zeolite and the presence of hydrogen. Coke deposition on Y zeolite was the reason for the decrease of LPG selectivity, but fortunately the selectivity of LPG could be recovered to a great extent by coke burning.