The sections in this article are Introduction and Overview History FCC Today Position in a Modern Petroleum Refinery Environmental Issues FCC Unit Hardware and Operations Unit Types Heat Balance Modes of Operation Regeneration Mode—Partial Burn vs. Full Burn Resid Processing Petrochemical Mode (Light Olefins) FCC Feeds Sources and Trends Molecular Types Characterization Effects on FCC Unit Operation Conradson Carbon and Feed Heaviness Feedstock Composition Metals: Ni , V , Na and Fe Sulfur Nitrogen The Chemistry of Catalytic Cracking Carbocations Formation of Carbocations Isomerization Reactions CarbonCarbon Bond Breaking by Beta‐Scission Hydride Transfer (also Referred to as Hydrogen Transfer) Heteroatom Chemistry: Sulfur FCC Catalysts Description and Formulation Zeolite Component Zeolite Modifications Zeolite Activity and Selectivity Effects Matrix Commercial Matrices Effect of Matrix on Selectivity Characterization ZSM ‐5 Additives FCCU Environmental Emissions Controls Overview—Catalyst Versus Hardware Particulates Carbon Monoxide ( CO ) Sulfur Oxides ( SO x ) Nitrogen Oxides ( NO x ) Laboratory Evaluations and Pilot Plant Testing Accelerated Aging of Catalysts Simulation of Metals Poisoning Reactor Types—Fixed Bed vs. Fluid Bed vs. Transport Phase Temperature Profile and Isothermal vs. Adiabatic Testing Summary and Future Trends in Catalytic Cracking

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.

The Fluid Catalytic Cracking (FCC) process remains the primary molecular weight reduction method practiced in modern petroleum refineries. While originally designed for cracking the overhead stream from vacuum distillation units, known as vacuum gas oil, most FCC units currently operate with some higher boiling vacuum distillation bottoms (resid) in the feed. Designing catalysts to tolerate the high level of metal contaminants in the resid, while still maintaining high conversion and selectivity, is a key issue of FCC catalyst design. While FCC feedstocks are becoming heavier and more metal contaminated, new demands are also being placed on the products produced. Demand for propylene is increasing more rapidly than steam cracking, the traditional source of propylene for chemical applications, can supply. Consequently, increasing quantities of propylene are being produced in the FCC process for use in chemicals and plastics. Highly propylene selective catalysts have been developed to meet this challenge. These catalysts, referred to as 'FCC olefin additives', are generally used in admixture with more traditional FCC catalysts. More stringent clean air requirements are also being imposed upon the FCC process. NO x emissions, produced by combustion of the coke during FCC catalyst regeneration, are being more strictly limited. FCC NO x reduction additives have been developed to minimize or reduce the amount of this pollutant produced by the FCC process. The impact of more stringent clean air requirements continues beyond the refinery gates, as lower gasoline sulfur levels are being mandated to reduce automobile emissions. Gasoline produced by the FCC process is the primary source of sulfur in the refinery gasoline pool. Fortunately, FCC catalyst technology is again providing an answer in the form of low sulfur gasoline FCC catalysts and catalyst additives.

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Zur drastischen Verminderung der SOX‐Emission in Abgasen des katalytischen Fließbettcrackens (FCC) wird ein Katalysatorkreislauf beschrieben, in dem an einem Metalloxid Schwefeldioxid und Schwefeltrioxid (90 : l0) mit Sauerstoff zu Schwefeltrioxid oxidiert und als Metallsulfat ausgeschleust wird (Regenerator).