Development Of The Non-toxic Composite Passivator

Using metal passivator can resolve effectively these issues, which is FCC catalyst heavy metal pollution as the FCC feed-oil getting worse and worse. Study on the nature of passivation active ingredients and passivation mechanism, selected non-toxic, highly efficient passivation group element; through the micro-activity test of catalyst, study a single group element passivation effect and the best experimental conditions; by mini-fixed bed catalytic cracking experiments to study the effect of composite passivator and found the suitable ratio of effective ingredient; analysis the action mechanism of passivators by XRD and TPR methods.Chose Mg and La as active element of Ni and V passivation respectively. Selected nitrate solution and triethanolamine to react, then added DMF to further react. The best reaction condition of Mg-based passivator were:molar ratio of Mg and triethanolamine 1.5-1.6, reaction temperature of triethanolamine 100℃, reaction time 3h; molar ratio of Mg and DMF 2, reaction temperature of DMF 100℃, reaction time1.5-2h. The best reaction condition of La-based passivator were:molar ratio of La and triethanolamine 0.9-1.0, reaction temperature of triethanolamine 40-60℃,reaction time 3h; molar ratio of La and DMF 0.15-0.25, reaction temperature of DMF 100-120℃,reaction time 2h. The suitable ratio of the composite passivator were:ratio of Mg and La 0.1-4, Mg content was lower than 3%. The synthetic product has good physical properties with good solubility in water, low sport viscosity and freezing point, the solution was neutral, high content of effective components.The passivator which active ingredients are Mg and La can Performance effectively. For Mg-based passivation agent, the most ratio is Mg/Ni molar ratio of 1.0,then the relative decline in hydrogen and coke yield 39.04% and 12.27%, MAT index increased by 5 units, increase of gasoline yield 1.23%. For La-based passivation agent, the most ratio is La/V molar ratio of 0.7, then MAT index increased 8.94 units, gasoline yield is increased by 4.65%, the relative decline in coke yield 16%. For the composite passivator agent, the best ratio is Ma/La molar ratio of 2, then conversion increased 6.63% than blank samples, MAT index increased by 7.4 units, the relative decline in hydrogen and coke yield 30.77% and 13.70%, increase gasoline and LPG yield 7.03% and 0.51%.The mechanism of pollution of Ni for FCC catalysts depends on its dehydrogenation activity, the lower the valence state of nickel is, the stronger the dehydrogenation activity of nickel is. Through XRD and TPR methods, after adding passivator, its active ingredients reacts with nickel to from MgNiO3,which is more difficult to be reduced by hydrogen under the reduction condition of FCC, so it can inhibit the strong dehydrogenation activity of nickel with low valence states, improve catalyst activity & selectivity. The mechanism of pollution of V for FCC catalysts depends on V2O5 and H3VO4 lower the crystallinity and acid sites. Through XRD method, after adding passivator, its active ingredients reacts with vanadium to from LaVO4, not only to avoid plugging the catalyst pores, but to stability of the zeolite crystal structure, thereby increasing the number of catalytic active sites and catalytic activity.