Artificially Metals-Poisoned Fluid Catalysts. Performance in Pilot Plant Cracking of Hydrotreated Resid

Abstract

Selectivity patterns for cracking hydrotreated resid at 1000 °F and 3-5 s contact time over equilibrium catalyst artificially poisoned with nickel and vanadium were studied. Conversion dropped only slightly, leveling out rapidly with increasing metals level, while C5+ gasoline yield showed an initial decline of 3%, but then remained constant. Coke on fresh feed increased sharply, nearly doubling at the 900 ppm level, out showed little increase thereafter. Hydrogen production increased sharply, but tended to flatten out after the 900 ppm level. The maxima in the gasoline yield occurred at lower conversion for the metals-poisoned catalysts than for the nonpoisoned base catalyst; octane numbers (R + O) with the poisoned catalysts (70-85 vol % conversion) were 87.5-90.0, about one R + O unit higher than the base. PONA analysis of C6+ gasoline showed no unusual trends. Total dry gas yields (wt %) showed little change due to metals poisoning, but composition changed.

Alternative to visbreaking or delayed coking of heavy crude oil through a short contact time, solid transported bed cracking process

“…It is well known that metals loading of a few thousand ppm on fluid catalytic cracking equilibrium catalyst does influence drastically conversion and selectivity, yielding more coke and more dry gas. 16 We have checked with kaolin that the yields from a same reaction (530ºC, solid to oil of 8 and residence time of 0.3 s) did not vary significantly after at least 40 runs ( Figure S1). That corresponds to an amount of approximately 600 ppm V and 200 ppm Ni deposited on the solid (500g solid inventory, 30g of crude oil processed per test).…”

Cracking and Hydrocracking

“…The last decades, and particularly the 1980s and 1990s, have seen an increasing share of residue processing, also in response to a declining demand for fuel oil. Residues also contain significant levels of various metals, of which nickel and vanadium (mostly present as porphyrins [56]) are particularly relevant to FCC because they can enhance coke make by acting as dehydrogenation catalysts [57]. Vanadium is moreover harmful because it catalyzes destruction of the zeolite lattice, probably by intermediacy of vanadic acid and possibly VO 2 + ions that exchange into the zeolite when vanadium is fully oxidized in the regenerator [58], or by formation of low-melting sodium vanadate when sodium is present [59].…”

Effect of pretreatment on the performance of metal-contaminated fluid catalytic cracking (FCC) catalysts

“…These metals increases the hydrogen and coke yields at the expense of gasoline [4,5]. These deposited metal contaminants are not removed during conventional catalyst regeneration operations during which coke deposits on the catalyst are converted to CO and CO 2 .…”