Studies On ZSM-11 Zeolite Used In Catalytic Pyrolysis Process Of Heavy Oil

As the increasing of heavy oil component in feed oil and the rising demand of low carbon olefin,ZSM-5 has been wildly used as a active component of the catalyst for heavy oil catalytic pyrolysis to improve the yield and selectivity of low carbon olefin.Just like ZSM-5,ZSM-11 is also one kind of Pentasil zeolite,and the two kinds of zeolite have the similar structure and composition.Now the research of ZSM-11 is mainly focused on the light hydrocarbon aromatization,the selective oxidation of styrene,etc.However the literature about the catalytic pyrolysis performance of ZSM-11 is very less.Therefore this paper systematically explored the catalytic pyrolysis performance of ZSM-11.In this paper the differences of structure and properties between ZSM-5(LTB-2)and ZSM-11(LQM-1)catalyst were characterized by means of XRD,SEM,N2 adsorption,FT-IR and NH3-TPD.The characterization showed that when compared with ZSM-5,ZSM-11 had shorter channel,larger space of channel’s intersections and more larger specific surface area.ZSM-11 also contained more mesoporous.However the acid amount and the B acid ratio was smaller than ZSM-5.Then the reaction performance of LTB-2(ZSM-5)and LQM-1(ZSM-11)was investigated under the condition of temperature was 500℃ and catalyst to oil weight ratio was 5.In this process FS-VGO and SH-VGO were used as raw materials.The results showed that the two catalysts had the similar ability of heavy oil conversion and selectivity of low carbon olefin.Besides the using of ZSM-11 as catalyst could improve the octane rating of gasoline and reduce the loss of gasoline yield at the same time.So the conclusions mentioned above showed that ZSM-11 had the property of producing more low carbon olefins and high-octane gasoline.The deactivation rule of LQM-1 catalyst was also investigated on the riser pilot unit under the condition of analog industrial by using SH-VGO as feed oil.The experiment results indicated that during continuous operation of 60 h when reaction temperature,regeneration temperature,resident time,water to oil weight ratio and catalyst to oil weight ratio were 540℃,700℃,9,0.2 and 1.8s,respectively,the relative crystallinity,specific surface area and acid quantity of the LQM-1 catalyst fell.In the meantime the conversion of the feed had a slight decrease and remained above 86%,the yield of dry gas and coke decreased while the yield of gasoline maintained nearly constant value.The yield of the LPG increased 4.36%,the yield of propylene increased from 15.33% to 18.37%,the yield of butylene increased from 11.22% to 14.24%.The olefin contents in dry gas,LPG and gasoline all increased.The effect of catalyst to oil weight ratio,reaction temperature and residence time on the catalytic pyrolysis performance of LQM-1 catalyst was studied on the riser pilot,and SH-VGO was also used as crude material.Results showed that considering the product yields and selectivity,when the reaction temperature was 540℃,catalyst to oil weight ratio was 9,resident time was 2.0s,the best product distribution could be obtained.Under the condition mentioned above,the conversion of the crude oil could reach 87.44%.The yield of dry gas and coke achieved 7.5% and 3.41%,respectively.The yield of the LPG was 20.61%,and the selectivity of propylene in LPG reached its maximum value which was 50.34%.The yield of gasoline was 24.62%.