Study On Canadian Oil Sand Bitumen Cracking-Coke Gasification Process And Catalyst

With the decline of the global oil reserve,the crude oil in the world has significantly become heavier in the past few years.The content of light fractions in crude oil has gradually decreased,and thus more and more refineries began the research of heavy oil or even extra-heavy oil upgrading.Canadian oil bitumen,as the world's unconventional oil resource,has been paid more and more attention all over the world.The residue cracking and coke gasification integrated process was used to study the Canadian oil sand bitumen cracking characteristics.The liquid product and the conversion rate are maximized by adjusting the catalyst activity,and then the coke on the catalyst is gasified in a high-temperature water vapor atmosphere to realize the recycling of the catalyst.At the same time,based on the pyrolysis results and the catalyst gasification activity by analysis of BET,NH3-TPD and XRD,a better type of catalyst is discussed for this heavy oil upgrading technological process.The main contents and results of this thesis are as follows:(1)Study on cracking characteristics of Canadian oil sands bitumen.The operating parameters of oil sands bitumen were optimized using FCC catalyst and bifunctional catalyst(BFC).The optimum operating parameters of oil sand bitumen were optimized with a small fluidized bed reactor in the laboratory and the optimum operating parameters were as follows: Cracking conversion temperature of 509 ?,catalyst/oilratio of 4.0,steam/oil ratio of 0.5.At the same time,it was found that the catalysts of both FCC and BFC's acidity were too high and could not meet the requirement of high liquid yield.After treated in 800? steam for 15 h,the A-BFC catalyst was generated.Under this reaction conditions,the liquid yield could reach more than 78%,with the conversion ratio of more than 85%.(2)Study on gasification characteristics of coked catalyst.Catalyst reactivity and the composition of the syngas after coke gasification were investigated.When the coke was gasified at 800?,the sum of CO and H2(volume fraction)can reach more than80%.The relationship among carbon content,gasification rate and pore size distribution in the coked catalyst with different gasification degree was analyzed via BET method.It was found that with the increasing degree of gasification,the carbon content of the catalyst was decreased and the pore structure gradually regained.After gasification,it cannot be restored to the initial level.Besides,in the process of gasification,gasification rate will reach the peak at the moment of "recovery elasticity".(3)Catalyst modification method and its effect on catalytic activity.The catalysts were subjected to different modification treatments: hydrothermal aging treatment,alkaline metal oxide loading and other treatment methods.Among them,the catalysts of A-FCC and A-BFC's acidity were significantly decreased after hydrothermal aging,and meanwhile the pore volume and pore structure were also improved greatly.Compared with the catalysts of Na-BFC,Ca-BFC and Mg-BFC,the K-BFC's reactivity is more suitable for the cracking of oil sand bitumen.As a result,the KA-BFC catalyst was obtained by impregnating potassium oxides on A-BFC.Its liquid yield was up to80.74%,and the conversion rate was 85.62%.Besides,the cracking stability of this catalyst was also satisfied in the cycle-tests.In addition,the loading of alkali metal oxides can help to speed up the gasification rate.As for the C-BFC-K catalyst,its gasification conversion can reach 97% within only 65 min.