Preparation Of Multifunctional Metal Passivator

In order to solve the problem that catalyst polluted by heavy metal in the process of FCC,metal passivator is used more and more widely. This experiment selects non-toxic, efficientpassivation group element magnesium, cerium; through the micro-activity test of catalyst,study single group element passivation effect and best experimental conditions; by mini-fixedbed catalytic cracking experiments to study the effect of magnesium, cerium based compositepassivation and found the suitable ratio of effective ingredient, analysis the action mechanismof passivators by XRD and TPR methods.The synthesis method of magnesium base passivator: Mg have coordination reaction withtriethanolamine, molar ratio of Mg and triethanolamine is1.5, reaction temperature oftriethanolamine is50℃, reaction time3h, then added DMF to further react, the molar ratio ofMg and DMF is2, reaction temperature of DMF is100℃, reaction time1.5~2h. The synthesismethod of cerium base passivator: cerium have reaction with triethanolamine, molar ratio ofcerium and triethanolamine is0.9~1, reaction temperature of triethanolamine is50℃, reactiontime3h, then added DMF to further react, the molar ratio of cerium and DMF is0.25, reactiontemperature of DMF is100℃, reaction time2h. The suitable ratio of the composite passivatorwere: ratio of Mg and Ce is0.1~4, Mg content was lower than3%.Investigate the effect of passivation by micro-activity test and mini-fixed bed catalyticcracking experiments. Mg-based passivation agent, when Mg/Ni ratio is1.0, the passivationeffect is best. Hydrogen and coke yields relative decline of nearly40%and12.5%, MAT indexincreased by5units, the yield of gasoline rose1.23%. When Ce/V ratio is0.7, the passivationeffect is best. MAT index rose nearly9units, the yield of gasoline increased nearly5%. Forthe composite passivator agent, the best ratio is Mg/Ce molar ratio of2, conversion increased6.63%than blank sample, MAT index increased by7.4units, the relative decline in hydrogenand coke yield31%and14%, gasoline and LPG also increased.Pollution of nickel and vanadium on FCC catalyst were reflected in the influence on theactivity and selectivity of catalyst. The lower valence state of nickel has strong activity ofdehydrogenation effective group of magnesium based passivation agent reacts with nickel toform a stable new phase MgNiO3, induce high valence state Ni change to low conversion,thereby reducing the dehydrogenation activity of nickel, improve the selectivity of catalyst. Vanadium compounds in the molten state can enter the zeolite pore, destroy the crystalstructure, cerium passivating agent effective component can react with vanadium compound,form compound CeVO4which has generating high temperature stability, to avoid meltingvanadium compounds blocked channels of the molecular sieve catalyst structure, protection,and enhance its activity.