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COMMERCIAL EXPERIENCE OF METAL PASSIVATOR ADDITIVE AND PERFORMANCE BENEFITS. Introduction. FCC/RFCC CATALYST 1913, Thermal cracking of oils-free radical mechanism 1915, AlCl 3 based cracking catalyst (Mc Afee) 1928, Houdry: solid/acid treated clay/ alumina based catalyst
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COMMERCIAL EXPERIENCE OF METAL PASSIVATOR ADDITIVE AND PERFORMANCE BENEFITS
Introduction FCC/RFCC CATALYST 1913, Thermal cracking of oils-free radical mechanism 1915, AlCl3 based cracking catalyst (Mc Afee) 1928, Houdry: solid/acid treated clay/ alumina based catalyst 1940, First synthetic silica-alumina catalyst 1948, Commercial production of microspheroidal FCC catalyst (Davison) 1962, Zeolite cracking catalyst 1974, CO-promoter 1975, Ni passivation, 1978, Vanadium passivation 1986, ZSM-5 based octane additive FCC HARDDWARE 1936, First fixed bed commercial cracking unit 1942, First commercial FCC unit (Standarad Oil) 1943, First commercial Thermofor catalytic cracking (TCC) 1956, First riser cracking unit (Shell Oil) 1971, Short contact riser (Kellog)
Introduction cont…. FCC/RFCC is flexible process Loading/unloading and switch over of catalyst/ additive Addition of catalyst / additive can be varied optimally as per the unit requirement. Performance of catalyst depends upon Process condition Feed properties Unit constraint change Product value change Product quality requirements
Challenges in processing of resid feeds Resid feeds High metal content, 3-15 ppm Ni and 10-30 ppm V, in the form naphthenates, porphyrins Higher sulphurcontent, 1.5-3 wt% Higher basic nitrogen, 500-1500 ppm CCR, 1-6 wt% Other issues Statutory requirement on products and effluent Limited catalyst suppliers, short supply of key component and rising cost
Rx Rg Challenges in processing resid feeds in RFCCU • Hardware limitation • Regenerator metallurgy • Combustion Air • Cyclone efficiency • Wet gas compressor 650-720OC 490-550 OC 5 Sec • Catalyst • High V tolerance • Low coke make • Higher thermal and hydrothermal • Higher attrition resistance with high zeolite content
Vanadium deactivation mechanism V-Porphyrins FCC catalyst in feed (V+3,V+5) V on catalyst surface with coke + Regenerator + O2 Reactor - reducing environment V2O5 (V+4, V+5) on surface Old catalyst Fresh catalyst Mobile (VO(OH)3, V+5) Steam + Rare Earth in Zeolite Particle to particle migration RE Vanadates, zeolite destruction
FCC catalyst particles with contaminate metals Binder : silica V Ni RE-Y zeolite Alumina/silica alumina Clay 3 micron
Structure of faujasite (Y) type zeolite 4 complete sodalite cages/UC 6 half sodalite cages/UC 8 one eighth sodalite cages/UC
Effect of metals on SA, feed rate, CCR and coke *CCR/feed rate based on model Coke Only option, replace with fresh catalyst
Options to combat Ni & V poisoning Addition of fresh catalyst Most common method, costly for higher catalyst consumption Feed hydrotreatment Attractive - many advantages, higher capital & operating costs Use of metal tolerant catalysts Difficult to balance between metal tolerance, activity & selectivity and cost Chemical demetallization-DEMET Sulfidation followed by chlorination-High cost technology Magnetic separation-Magnacat Requires large capital, difficult to remove vanadium Use of liquid passivators & solid additives
Type of metal passivator / trap additive FCC Additives V-Trap additive (solid/liquid) Rare earth MgO/Alumina Tin Ni passivator (liquid emulsions) Antimony Bismuth Cerium
IndVi: Additive for simultaneous passivation of Ni & V ABD: 0.78-0.91 gm/cc, AI < 4, SA: 60-70 m2/gm, APS: 85-100 micron Dosage : 1-10 wt%
Laboratory testing • Metal deactivation protocol • Blending 5 wt% additive with base catalyst • Metal doping (Ni-2500 & V-6852)-Mitchell method • Single step H2 reduction • Hydrothermal deactivation at 788 deg.C/3hrs • Measurement of physico- chemical properties • Performance evaluation – ACE R+ unit
Impact of IndVi on physical properties & Coke 5 wt% IndVi, reduced coke from 1 to 1.9 wt% for cat/oil ranging from 3.3 to 5.6
Predicted plant performance yield – Increasing t’put
Commercial production Toll manufacturing at SCIL • Manufactured 12 MT IndVi additive for plant trial in M/s SCIL facilities. • Physico-chemical characteristics of commercial lot match with laboratory catalysts.
Commercial trial cont.. PLANT TRIAL – RFCCU • Plant trial run of IndVi additive was conducted in RFCCU for 20 days with 4.5% additive concentration. During the PGTR, ZSM-5 was added to the system @ 100 kg/day along with fresh catalyst addition rate of 4 MT/hr. • Around ~3 wt% TCO yield increased with more or less corresponding decrease in gasoline yield. Reduction in gasoline yield and increase in TCO yield in line with the current Refinery objective. • VR addition rate was increased by 3.2 m3/hr during the trial run due to increased available cushion in regenerator dense bed temperature. Even with higher VR rate, RG1 dense bed temperature was lower by 7 oC compared to base case.
Conclusion • Ni & V are the prominent metals accumulating on catalyst which reduce crystallinity, SA and activity and increases coke & dry gas yield. • IndVi additive developed & Commercialized by IOCL is capable of simultaneous passivation of both vanadium and nickel. • Presence of additive in RFCC unit, helps in retaining higher surface area and crystallinity. • Predicted plant performance yield based on laboratory data showed reduction in bottom and increase in distillate yields. • Commercial plant trial of IndVi at HR RFCC unit showed: • Enhanced t’put containing higher VR • Enhanced TCO yield • Lower regenerator-1 dense bed temperature (by 7oC) at higher t’put, • Comparable CLO yield similar to base case
The Authors acknowledge the contribution of followings towards successful commercial plant trial mr g. saidulu drv.chidambaram mrbalaiah swam Mr.S.p.Choudhury dr.m.b.patel dr.j.christopher mr.somnathkukkade mr.manojkumaryadav ms. Soma chattopadhyay Ms sangeetaPurkaystha Mr sujitdasgupta
Catalyst deactivation- chemistry 1. V deposits on catalyst surface along with coke 2. V2O5 generates in oxidative environment • 4 V + 5 O2 2 V2O5 • Vanadium oxide converted in vanadic acid in presence of reducing environment (steam) • V2O5 + 3 H2O 2 VO (OH)3 La2O3 + 2H3VO4 2LaVO4 + 3H2O Al2O3 + 2H3VO4 2AlVO4+ 3H2O
Properties of Ni on RFCC catalyst Ni exists under FCC condition as +2 or 0 valance state Ni is 4 times more active than vanadium and it’s activity is more predominant with higher alumina content in catalyst +2 state of nickel reacts to form NiAl2O4and NiSiO3 with surface alumina and silica. NiSiO3 is more stable, SiO2 based binders are preferred as natural passivators for Ni
V & Ni passivating agents Ni Passivation Antimony, Bismuth and Cerium based emulsions are in use as additive along with hydrocarbon feed Natural SiO2 based binder partially mitigates undesired effects Additive catalysts based on Sb, Bi have been in use as blend with base catalyst Order of passivation-Sb > Bi > Sn > P >Al V Passivation Tin, Antimony, Titanium, Zirconium and Rare earth based passivators are in already use for vanadium passivation Alumina based metal trap partially passivates destructive behavior of vanadium