A tetrathiotungstate-intercalated NiAl layered double hydroxide (LDH) was synthesized and then calcined under N2 at various temperatures to prepare a series of NiW presulfurized hydrotreating catalysts. Upon calcination, WS42– in the interlayer decomposes into WS3 and then WS2, releasing sulfur to sulfurize nickel in the sheets. The property and activities of catalysts for hydrodesulfurization (HDS) of dibenzothiophene and hydrodearomatization (HDA) of tetralin are dependent on the calcination temperature. At 300 °C, WS3 can be well maintained, offering highly active hydrogenation sites S22– and superior HDA activity. As the temperature increases up to 500 °C, WS3 converts into WS2, while nickel sulfides migrate to the edge of WS2 to form NiWS phases with high HDS activity. LDH-based presulfurized catalysts can achieve fully sulfurized and well-dispersed tungsten species even at high tungsten loadings and can retain more WS3 even at high temperatures because of the peculiar properties of LDHs. Therefore, they show better HDS and superior HDA activities over an oxidic NiW LDH-based catalyst (LDO) and an alumina-supported NiWS presulfurized catalyst (NiWS/Al2O3). The optimized catalyst shows 1.59 and 1.05 times higher HDS activity than LDO and NiWS/Al2O3 while 2.05 and 1.77 times higher HDA activity than LDO and NiWS/Al2O3, respectively. It also shows better HDS and HDA activity for a real diesel than a NiCoMoW/Al2O3 commercial catalyst.
The effect of thermal pretreatment on the bifunctional NiW catalyst and its hydrodeoxygenation (HDO) performance on oleic acid were investigated. Increasing the calcination temperature (CT) not only led to the growth of NiW particles, but caused the migration of Ni to the surface that resulted in the segregation of W. The reduction temperature (RT) was also able to tune the catalyst surface composition. A lower RT (600 °C) led to a W-rich surface, while a higher one (700 °C) interestingly resulted in a Ni-rich surface. To this end, the ratio of surface-active sites, i.e. , the partially reduced W species (W δ + ) to Ni 0 ones (W δ + /Ni 0 ), was manipulated. The highest W δ + /Ni 0 ratio of 2.6 was reached at the CT and RT of 550 °C and 700 °C, respectively, which contributed to an impressively high solvent-free deoxygenation of 95.1% at only 300 °C. The deoxygenation rate (r deoxy. ) was much higher than that of the reported non-precious catalysts, even comparable to the precious ones. Additionally, a high catalyst durability was found on non-acid feedstocks like triglycerides , long-chain alcohols, etc. , but an acidic substrate like oleic acid tended to leach the loaded metals that eventually lessened the HDO activity.
危险品化学品经营许可证（带存储）