Research On Effect Of Rare Earth On Catalytic Cracking Catalyst And Resistant Performance Of Nickel And Vanadium

Fluid catalytic cracking (FCC), one of the major down-stream refining operating process,is responsible for the conversion of heavy feedstocks into lighter. The more valuable productscan be acquired through FCC, such as liquefied petroleum gases and cracked naphtha, themajor constituent of the gasoline pool. The FCC catalyst is a porous microsphere containing Yzeolite, active or inert matrix, and a silica or alumina binder. In the catalytic cracking process,the FCC catalyst goes through reaction, stripping and regeneration phases in the reactor andthe regenerator so that the performance of the catalyst is changed; at the same time, differentamount of contamination metals such as nickel, vanadium and iron contained in feedstock oilcould cause the catalyst to contaminating and poisoning. While the evaluation method of thecatalyst has some deficiencies, as a consequence, it is particularly significant to research theaging and contaminating methods of the catalyst.Porphyrin-based organic compounds contained in the feedstock oil are continuouslydeposited on the catalyst surface. During reaction the nickel as organometallic compoundsconverted to NiO and Ni, the activity and product selectivity of catalyst deteriorated becauseof the neckel dehydrogenation catalytic performance and the clogging effect to the zeolitepore canals; during reaction the vanadium as organometallic compounds converted to V2O5and then transformed to acidic species in the presence of steam, the activity and productselectivity of catalyst changed because of the hydrolysis of the framework structure of zeoliteand destroyed the crystalline structure of zeolite. As a special kind of metal element, the rareearth elements play a decisive role in the oil industry. In the period of time, the rare earthenters into the zeolite by ion exchange, which has the effect such as stabilizing the zeolitecrystal structure, improving the thermal and hydrothermal stability, improving the activity andthe yield of light oil and so on. Present, the research of nickel and vanadium resistantperformance by using rare earth has become a hot topic. The rare earth can generate a stableNiREO3with nickel, which inhibit the formation of NiO and Ni to weaken the effect of nickelon catalysts. It also can inhibit the migration of vanadium to weaken the destruction ofvanadium on zeolite through the generation of stable REVO4with vanadium. If achieved thedouble passivation of nickel and vanadium by using rare earth, which can greatly improve theefficiency of catalytic cracking process and the life of FCC catalyst.The different FCC catalysts as material, this research direct to the effect of nickel andvanadium on catalysts and resistant performance of nickel and vanadium. Four aspects areinvestigated by using the experimental methods of simulating the actual industrial process:(1)The change law of FCC catalyst performance in cyclic aging process, and compared with thehydrothermal aging process;(2) The cyclic contaminating and aging method of nickel andvanadium as organometallic compounds is established through combined hydrothermal agingprocess with cyclic contaminating process;(3) The effect of nickel and vanadium on catalystsis studied from the contaminate amount of nickel and vanadium, the form of nickel and vanadium and the contamination method;(4) With studying the single nickel or vanadiumresistant performance and the hybrid nickel and vanadium resistant performance, the paperexpounds nickel and vanadium resistant performance using rare earth.The result showed that the catalysts’ properties are approaching the hydrothermal agingcatalysts with the increase of cyclic times through the cyclic aging process, but their productyield have difference and this processing is too long; In the process of the laboratory cycliccontaminating and aging of nickel and vanadium as organometallic compounds, thedeposition ratio of nickel and vanadium is closely related with the ratio of catalyst to oil andthe times of cyclic contaminate reaction. The experiment plan of cyclic contaminating andaging has been effectively set and the control of the contamination of nickel and vanadium inthe process of cyclic contamination has been achieved to a certain extent though thecorresponding function relationship; With increasing the contamination amount of nickel andvanadium, the performance of the catalyst become deteriorated, the damage of nickel andvanadium as organometallic compounds is relatively serious and the different method ofcontaminating and aging have different effects on the properties of catalysts; The rare earthcomponent of different forms and distribution in the catalyst can effectively improve nickeland vanadium resistant performance, the independent RE2O3in the catalyst has betterresistant performance of nickel and vanadium than the RE3+in the zeolite frame, the RE2O3inthe matrix has resistant performance of nickel, the RE2O3in the zeolite surface has resistantperformance of vanadium.