To better understand the nature of carbon nanotubes supported Co-Mo catalysts （Co-Mo/CNTs） for selective hydrodesulfurization （HDS） of fluid catalytic cracking （FCC） gasoline, studies are carried out using in si...To better understand the nature of carbon nanotubes supported Co-Mo catalysts （Co-Mo/CNTs） for selective hydrodesulfurization （HDS） of fluid catalytic cracking （FCC） gasoline, studies are carried out using in situ Fourier transform infrared spectroscopy （FT-IR）. The catalytic performances of Co-Mo/CNTs catalysts were evaluated with a mixture of cyclohexane, diisobutylene, cyclohexene, 1-octene （60 ： 30 ： 5 ： 5, volume ratio） and thiophene （0.5%, ratio of total weight） as model compounds to simulate FCC gasoline. The HDS experimental results suggested that the HDS activity and selectivity of Co-Mo/CNTs catalysts were affected by Co/Mo ratio; the optimal Co/Mo atomic ratio is about 0.4, and the optimum reaction temperature is 260 ℃. The in situ FT-IR studies revealed that 1-octene can be completely saturated at 200 ℃. In the FT-IR spectra of diisobutylene, the characteristic absorption peak around 3081 cm^-1 for the stretching vibration peak of =C-H bond was still clear at 320 ℃ indicating that diisobutylene is difficult to be hydrogenated. As for the thiophene, no characteristic absorption peak could be found around 3092 cm^-1 and 835 cm^-1 when the reaction temperature was raised to 280 ℃, indicating that thiophene had been completely hydrodesulfurized. On the basis of FT-IR results, it can be deduced that thiophene HDS reaction occurred mainly through direct hydrogenolysis route, whereas thiophene HDS and diisobutylene hydrogenation reaction over Co-Mo/CNTs catalysts might occur on two different kinds of active sites.展开更多
The demand for propylene has been growing recently. The concentration of olefins in the gasoline is strictly limited by the related environmental regulations. The olefins contained in the gasoline used as the feed cou...The demand for propylene has been growing recently. The concentration of olefins in the gasoline is strictly limited by the related environmental regulations. The olefins contained in the gasoline used as the feed could be cracked into light olefins to slash the olefin concentration in the gasoline to yield more propylene at the same time. The monolithic catalyst washcoated on the modified ZSM-5 zeolite was used in the experiments. The effect of the temperature, the Si/Al ratio in ZSM-5 and the addition of the rare earth elements on the selectivities and the yields of the light olefins were studied. The high yields of propylene and butene could be obtained under the experimental conditions of a higher temperature and Si/Al ratio with the addition of rare earth elements.展开更多
FCC units are playing an important role at refineries, in particular at Chinese refineries. To cope with the current demand for better economic benefits, environmental protection and product slate adjustment, a host o...FCC units are playing an important role at refineries, in particular at Chinese refineries. To cope with the current demand for better economic benefits, environmental protection and product slate adjustment, a host of FCC units need to be technically revamped. This article describes the practical processes, technologies and equipment to serve different revamp targets with analysis of two examples on revamp of commercial units.展开更多
基金National Basic Research Program of China ("973"Program,No.2004CB217807)
文摘To better understand the nature of carbon nanotubes supported Co-Mo catalysts （Co-Mo/CNTs） for selective hydrodesulfurization （HDS） of fluid catalytic cracking （FCC） gasoline, studies are carried out using in situ Fourier transform infrared spectroscopy （FT-IR）. The catalytic performances of Co-Mo/CNTs catalysts were evaluated with a mixture of cyclohexane, diisobutylene, cyclohexene, 1-octene （60 ： 30 ： 5 ： 5, volume ratio） and thiophene （0.5%, ratio of total weight） as model compounds to simulate FCC gasoline. The HDS experimental results suggested that the HDS activity and selectivity of Co-Mo/CNTs catalysts were affected by Co/Mo ratio; the optimal Co/Mo atomic ratio is about 0.4, and the optimum reaction temperature is 260 ℃. The in situ FT-IR studies revealed that 1-octene can be completely saturated at 200 ℃. In the FT-IR spectra of diisobutylene, the characteristic absorption peak around 3081 cm^-1 for the stretching vibration peak of =C-H bond was still clear at 320 ℃ indicating that diisobutylene is difficult to be hydrogenated. As for the thiophene, no characteristic absorption peak could be found around 3092 cm^-1 and 835 cm^-1 when the reaction temperature was raised to 280 ℃, indicating that thiophene had been completely hydrodesulfurized. On the basis of FT-IR results, it can be deduced that thiophene HDS reaction occurred mainly through direct hydrogenolysis route, whereas thiophene HDS and diisobutylene hydrogenation reaction over Co-Mo/CNTs catalysts might occur on two different kinds of active sites.
文摘The demand for propylene has been growing recently. The concentration of olefins in the gasoline is strictly limited by the related environmental regulations. The olefins contained in the gasoline used as the feed could be cracked into light olefins to slash the olefin concentration in the gasoline to yield more propylene at the same time. The monolithic catalyst washcoated on the modified ZSM-5 zeolite was used in the experiments. The effect of the temperature, the Si/Al ratio in ZSM-5 and the addition of the rare earth elements on the selectivities and the yields of the light olefins were studied. The high yields of propylene and butene could be obtained under the experimental conditions of a higher temperature and Si/Al ratio with the addition of rare earth elements.
文摘FCC units are playing an important role at refineries, in particular at Chinese refineries. To cope with the current demand for better economic benefits, environmental protection and product slate adjustment, a host of FCC units need to be technically revamped. This article describes the practical processes, technologies and equipment to serve different revamp targets with analysis of two examples on revamp of commercial units.
