Co‐processing of rapeseed oil — straight run gas oil mixture: Comparative study of sulfide CoMo/Al2O3-SAPO-11 and NiMo/Al2O3-SAPO-11 catalysts

Abstract

Co-processing of mixture, containing 30 wt.% of rapeseed oil (RSO) in straight run gas oil (SRGO), was studied over stacked bed sulfide catalytic system containing Mo/Al2O3 as a first layer and CoMo/Al2O3-SAPO-11 or NiMo/Al2O3-SAPO-11 catalyst as the second one. The experiments were performed in a trickle bed reactor at 350−380 °C, 4.0–7.0 MPa, 1.5 h−1 and 1000 Nm3/m3. The hydrodeoxygenation (HDO) of RSO is proceeding over Mo/Al2O3 catalyst mostly through direct HDO route (selectivity > 93 %). The proposed combination of catalysts minimizes the formation of carbon monoxide, that is known as an inhibitor of hydrotreating reactions and can affect the hydroisomerisation/hydrocraking of alkanes over CoMo/Al2O3-SAPO-11 and NiMo/Al2O3-SAPO-11 catalysts. The effects of temperature and pressure on the behavior of Mo/Al2O3-CoMo/Al2O3-SAPO-11 and Mo/Al2O3-NiMo/Al2O3-SAPO-11 systems were studied and the difference in the quality of products were discussed with the emphasis on the cold flow properties. The cloud point of products, obtained in the co-processing of RSO-SRGO mixture over Mo/Al2O3-CoMo/Al2O3-SAP and Mo/Al2O3-NiMo/Al2O3-SAP catalytic systems was decreased to −8 and −13 °C respectively with the temperature increase from 350 to 380 °C. In addition, the hydrogenated products produced over NiMo/Al2O3-SAP were characterized by lower final boiling point values and aromatic content in comparison with that produced over CoMo/Al2O3-SAP catalyst. Unexpectedly, the opposite effect of pressure was observed on the cloud point and the conversion of long chain alkanes, which were produced in hydrodeoxygenation of RSO.