One-step catalytic conversion of syngas to aromatics over ZrO2 catalyst

A series of ZrO2 nanoparticles with different particle sizes and different crystalline phases were prepared using coprecipitation and hydrothermal methods. Their physico-chemical properties were characterized by N2 physisorption, XRD, TEM, Raman spectroscopy, XPS, and NH3-TPD techniques. The catalytic performances for syngas conversion were tested at 400℃, 3 MPa, gas hourly space velocity (GHSV) of 500 mL/(gcat·h), and H2/CO/Ar (volume ratio)=5∶5∶1. It was found that syngas can be directly converted into hydrocarbons over ZrO2 nanoparticles. The hydrocarbon products are mainly composed of isomerized olefins, cyclenes, and aromatics. The selectivity of C5+ hydrocarbons is up to 48%. Moreover, the aromatic concentration in C5+ ranges from 30% to 53% depending on ZrO2 structures. It is also found that the monoclinic ZrO2 shows higher activity than the tetragonal one. Monoclinic ZrO2 with larger specific surface area and acid amount show highest CO conversion as well as the yield of target products, but the monoclinic ZrO2 with lager particle size has the higher acid surface density and results in the higher aromatic selectivity. Consequently, acidity is the key factor for CO conversion. And high acid surface density promotes the formation of aromatics but acid amount affects the activity. © 2016, Science Press. All right reserved.