Upgrading of light cycle oil via coupled hydrogenation and ring-opening over NiW/Al2O3-USY catalysts

A series of ultrastable Y (USY) zeolite samples with different acidities and pore sizes are prepared via hydrothermal and acid treatments. NiW sulfide catalysts are maintained on a mixed support of USY zeolite and Al2O3. The catalytic coupled hydrogenation and ring-opening performance are studied on a continuous fixed-bed reactor using tetralin as the model compound. All catalysts show high tetralin conversions under the reaction conditions studied [T = 613 K, P = 4.0 MPa, LHSV = 2.0 h−1, H2/oil (v/v) = 500]. Product yields and selectivity are mainly determined by the zeolite property (i.e., acidity). A medium to strong zeolite acidity is the key factor in the ring-opening selectivity of tetralin. A maximum high cetane ring-opening product yield of 39.1 wt% is obtained at a C10 yield of 98.2 wt% for a USY zeolite with medium acidity. Using an fluid catalytic cracking light cycle oil feedstock, the activity of the catalyst is higher than that of commercial catalysts, giving a 14-unit cetane number increase at a diesel yield of 97.6 wt%. Because the first step of the ring-opening reaction is hydrogenation, the catalyst must have high hydrogenation activity. The WS2 slabs have a high average layer number of 2.7 on the catalyst using the support presented here.