Effect of morphology properties of NiW catalysts on hydrodesulfurization for individual sulfur compounds in fluid catalytic cracking diesel

Abstract

Three catalysts NiW/Al2O3, NiW–P/Al2O3 and NiW–CA/Al2O3 with different morphologies but similar pore structures and acidity properties were prepared for studying the effect of morphology properties on the hydrodesulfurization (HDS) activity for individual sulfur compounds in fluid catalytic cracking (FCC) diesel. The morphology properties of the selected catalysts in oxidation and sulfidation states were characterized and the contents of individual sulfur compounds were determined by gas chromatography–pulse flame photometric detector (GC–PFPD). The results showed that NiW–P/Al2O3 possessed the highest edge density of WS2 phase and NiW–CA/Al2O3 had the highest stacking degree of multilayered WS2 phase. The HDS assessment showed that NiW–CA/Al2O3 demonstrated positive effects on the HDS of refractory sulfur compounds like 4,6-dimethyldibenzothiophene (4,6-DMDBT) or dibenzothiophene (DBT) with alkyl substitutes containing 3 carbons (C3DBT) but slight negative effects on the HDS of simple sulfur compounds such as benzothiophene (BT) with alkyl substitutes containing 1~5 carbons (C1~C5BT) and DBT with alkyl substitutes containing 1 carbon (C1DBT); while NiW–P/Al2O3 favored for the HDS of simple sulfur compounds. The present results indicated that the morphology of WS2 phase has a great influence on the HDS selectivity for different structured sulfur compounds.