Of FCC products

Desulfurization of FCC feedstocks reduces the sulfur content of FCC products and SOX emissions. In the United States, road diesel sulfur can be 500 ppm (0.05 wt%). In some European countries, for example in Sweden, the sulfur of road diesel is 50 ppm or less. In California, the gasoline sulfur is required to be less than 40 ppm. The EPA s complex model uses sulfur as a controlling parameter to reduce toxic emissions. With hydroprocessed FCC feeds, about 5% of feed sulfur is in the FCC gasoline. For non-hydroprocessed feeds, the FCC gasoline sulfur is typically 10% of the feed sulfur. 

This chapter discusses the factors affecting yields and qualities of FCC product streams. The section on FCC economics describes several options that can be used to maximize FCC performance and the refinery s profit margin. 

Feed hydrotreating or hydrocracking reduces SOj, emissions and the sulfur content of FCC products. As discussed earlier in this chapter, many benefits are associated with FCC feed hydrotreating. It is important to note that most of the sulfur in a hydrotreated feed is in heavy organic compounds and will be concentrated in the decanted oil and coke. Consequently, for a given sulfur in the feed, more SO, will be produced with hydrotreated feed. 

In the second part of the work, 2-D chromatography using a Zoex system 2-D chromatography kit with a 15 m x 0.25 mm x 1 pm nonpolar DB-1 column coupled to a 1.5 m X 0.25 mm x 1 pm polar Carbowax column was used for LCO speciation. Figures 2.2 and 2.3 show 2-D chromatograms of FCC products from two catalysts compared at similar slurry oil yields. Figure 2.2 is from the product of the novel... 

The FCC process is the most important refinery process mainly for the production of gasoline from heavy petroleum fractions, such as atmospheric and vacuum gas oil (VGO). In the FCC unit, the long hydrocarbons are cracked in the 480—540°C temperature range over zeolite catalysts to smaller n- and i-parafiins, n- and i-olefins, and aromatics. Conventional FCC feedstocks are relatively aromatic, with a high sulfur and nitrogen content, in contrast to FT waxes that are highly paraffinic with extra-low aromatics content (<1 wt%) and viitually zero sulfur (<5 ppm) (see Table 18.4). The development therefore of new catalyst formulations, as well as optimization of the overall process parameters, are both very critical to optimize the yield and quality of FCC products from FT waxes. 

One can react methanol with the tertiary olefins having five c irbon atoms (isoamylenes). This process increases the octane number of FCC olefinic C5 fractions, in order to reduce the concentration of olefins and to increase gasoline production. 

Other components in the feed gas may react with and degrade the amine solution. Many of these latter reactions can be reversed by appHcation of heat, as in a reclaimer. Some reaction products cannot be reclaimed, however. Thus to keep the concentration of these materials at an acceptable level, the solution must be purged and fresh amine added periodically. The principal sources of degradation products are the reactions with carbon dioxide, carbonyl sulfide, and carbon disulfide. In refineries, sour gas streams from vacuum distillation or from fluidized catalytic cracking (FCC) units can contain oxygen or sulfur dioxide which form heat-stable salts with the amine solution (see Fluidization Petroleum). 

Rotating machinery usually performs efficiently if it works under design point conditions. However, off-design conditions require a predictive model of the machine s performance. In a FCC power train system, mass flow deviation is quite common for adjusting production capacity to meet the requirements of petrochemical product markets. 

Olefins are not the preferred feedstocks to an FCC unit. This is not because olefins are inherently bad, but because olefins in the FCC feed indicate thermally produced oil. They often polymerize to form undesirable products, such as slurry and coke. The typical olefin content of FCC feed is less than 5 wt%, unless unhydrotreated coker gas oils are being charged. 

Aniline is an aromatic amine (CgHjNHj). When used as a solvent, it is selective to aromatic molecules at low temperatures, and paraffins and naphthenes at higher temperature. Aniline is used to determine aromaticity of oil products, including FCC feedstocks. Aniline point (AP) is the minimum temperature for complete solubility of an oii sample in aniline. 

Although desulfurization is not the goal of cat cracking operations, approximately 50% of sulfur in the feed is converted to HjS. in addition, the remaining sulfur compounds in the FCC products are lighter and can be desulfurized by low-pressure hydrodesulfurization processing. 

As with HjS, the distribution of sulfur among the other FCC products depends on several factors, which include feed, catalyst type, conversion, and operating conditions. Feed type and residence time are the most significant variables. Sulfur distribution in FCC products of several feedstocks is shown in Table 2-4. Figure 2-9 illustrates the sulfur distribution as a function of the unit conversion. 

Sulfur Distribution of the FCC Products as a Fuction of Unit Conversion... 

Figure 2-9. Sulfur distribution of the FCC products as a function of unit conversion.

FCC products are commonly reported, on an inert-free basis, as the volume and weight fractions of the fresh feed. In a rigorous weight... 

Adding ZSM-5 catalyst additive is another process available to tlie refiner to boost production of light olefins. ZSM-5 at a typical concentration of 0.5 to 3.0 wt% is used in a number of FCC units to increase the gasoline octane and light olefins. As part of the cracking of low octane components in the gasoline, ZSM-5 also makes C. C4, and Cj olefins (see Figure 6-2). Paraffinic feedstocks respond the most to ZSM 5 catalyst additive.. 

Catalytic coke is a byproduct of the cracking of FCC feed to lighter products. Its yield is a function of conversion, catalyst type, and hydrocarbon/catalyst residence time in the reactor. 

More competitive refining industry. The run length of the early FCC units was very short the unit was shut down every year or so. The general approach at the time was to make the necessary repairs and replace the damaged internal components. Once the industry became more competitive, the drive was to increase the unit s run length, improve its reliability, and maximize the quantity and quality of desired products. 

Conversion is often defined as the percentage of fresh feed cracked to gasoline, lighter products, and coke. Raw conversion is calculated by subtracting the volume or weight percent of the FCC products (based on fresh feed) heavier than gasoline from 100, or ... 

Carbon Monoxide Boilers Carbon monoxide boilers are used to recover waste heat generated from oil refining fluid catalytic cracking (FCC) processes. The FCC process produces copious volumes of by-product gas containing 5 to 8% carbon monoxide (CO), which has a heat content of about 150 Btu/lb. A 10,000 barrel (bbl) per day FCC unit produces 60,000 to 150,000 lb/hr of CO. 

Erythorbic acid is available as a 98+% Food Chemical Codex product (as per Pfizer sodium erythorbate FCC, although as Pfizer is now a pharmaceuticals company, much of the world s erythorbate is now supplied from China and other Asian countries) and in many diluted or blended forms, such as Nalco Sur-Gard . The ONDEO Nalco material is typical of products used within the industry, being based on erythorbic acid buffered with amine. A 1% solution of the product has a pH level of 6.3. 

Reaction of Li[Fc(NCy)2l with 0.5 equivalents of [Rh(CO)2(/t-Cl)]2 formed orange [FcC(NCy)2]Rh(CO)2 in good yield. Chemical oxidation of [FcC(NCy)2]Rh(CO)2 with AgBF4 generated the amidine-containing product [ FcCfNCylNHCylRhfCOlJlBFJ (Scheme 150). ... 

Thus, a large focus of FCC catalyst research involves control of the density and location of acid sites in order to control product selectivity, product quahty and coke make. In a landmark publication Pines [30] demonstrated how widely spaced framework A1 sites may be utilized to produce high octane gasolines by decreasing hydrogen transfer reactions which in turn results in preservation of olefins. 

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