Additives in FCC

Other applications for molecular sieve catalysts for the production of olefins include the use of ZSM-5 additives in FCC units to increase propylene yield and the... 

In addition to increased severity, catalyst additives such as ZSM-5 can be used to increase FCC olefin yields. Hsieh et al. (in print) report on the use of additives in FCC including the family of ZSM-5 type materials. Young et al. (1991) give examples from the pilot plant of olefin yield increases (and gasoline yield losses) when employing 4% of a ZSM-5 type material. 

FDA Quality Standards. Although standards for many dmgs and biologicals are included in the USP—NF, and for many food additives in the FCC, the FDA also estabhshes some specifications of its own. In the dmg field, specifications and testing methods for antibiotics and biologicals are set by the FDA. Also, specifications and testing methods are prescribed for colorants. Many food-additive petitions are granted with the requirement that certain specifications are met. 

Multiftmctional SO removal catalyst systems have been ia commercial use siace 1985 ia the United States. Such systems have successfully reduced SO emissions in the FCCU regenerator by 50% when the regenerator is operating in the complete CO combustion mode (45). Modern-day additives can achieve a 50% SO reduction with only IS—2% of the additive in the circulating inventory, an amount small enough not to interfere with the cracking characteristics of the bulk FCC catalyst (45). 

The breakthrough in FCC catalyst was the use of X and Y zeolites during the early 1960s. The addition of these zeolites substantially increased catalyst activity and selectivity. Product distribution with a zeolite-containing catalyst is different from the distribution with an amorphous silica-alumina catalyst (Table 4-3). In addition, zeolites are 1,000 times more active than the amorphous silica alumina catalysts. 

The main components of FCC catalysts are Zeolite Y, e.g., REY orUSY as the major active component (10 to 50%), and a binder that is typically an amorphous alumina, silica-alumina, or clay material. In addition to these main components, other zeolite components, e.g., ZSM-5, and other oxide or salt components are quite frequently used additives in the various FCC catalysts available on the market. The addition of 1 to 5% ZSM-5 increases the octane number of the gasoline. ZSM-5 eliminates feed compounds with low octane numbers because it preferentially center-cracks n-paraffins producing butene and propene [14], These short-chain olefins are then used as alkylation feedstocks... 

In FCC applications, ZSM-5 has been used primarily in the form of a high concentration, separate particle additive, since this method affords maximum flexibility. However, it has also been successfully employed as a composite catalyst containing both ZSM-5 and the faujasitic cracking component in the same particle (11). 

It has been ten years since Amoco announced the UltraCat process O) for SOx control in FCC units. In those ten years, as well as in the years previous to the announcement, much work was done to develop catalysts that would control SOx emissions. The evidence is the 80 or more U.S. patents that have issued in that time to Amoco and others. One of the first patents issued was to Amoco in 1974 ( ) for the addition of magnesia and other group IIA oxides to cracking catalyst. This paper reviews the SOx catalyst developments and emphasizes the work done at Amoco to identify the active materials, explain the deactivation mechanism and, finally, to make a side-by-side comparison of various catalytic systems that are being pursued commercially today. 

With the development of 2-D chromatography, direct hydrocarbon speciation in the LCO range for synthetic crudes produced in FCC laboratory reactors became possible. The new method in addition to a greater understanding of the mid-distillate chemical composition avoided the effect of variations in light naphtha condensation efficiency on total aromatics. The C5 + fraction lost to the gas phase will concentrate aromatics in the liquid phase and numerical compensation by adding the gas phase C5s back to the liquid phase and is subject to errors because of the low precision of C5 + determination in the gas phase. 

Magnesium-based materials are used as the pick-up agent in currently available additives. In the FCC regenerator, the additive reacts with SO3 to form magnesium sulfate ... 

The FCC catalyst may affect SO emissions. The active alnmina in FCC catalysts plays a limited role as a pick-np agent for SO3 (similar to MgO). However, the fresh catalyst lacks the oxidants that enhance the effectiveness of SOx reduction additives. 

Cracking (FCC) units have been established through consent decree between the EPA and the rehnery or by the application of new source review (NSR) provisions of the Clean Air Act when making rehnery modihcations that result in a signihcant emission increase. NSR standards require facilities to apply best available control technology (BACT) in ozone attainment areas and the lowest achievable emissions rate (LAER) in ozone nonattainment areas. In addition, in mid-2009, the U.S. EPA revised the Standards of Performance for Petroleum Rehneries (40 CFR 60 Subpart Ja) to include NO, standards for process heaters and FCCUs. 

The same technology nsed in a catalytic converter was the starting point for use of additives to reduce NO in FCC nnits. The ability of these metal oxide materials to store and release oxygen affects the oxidation and reduction of coke nitrogen in the regenerator. 

Extensive studies describe the development of new materials, such as transition-metal nitrides and oxynitrides, as new potential catalysts for hydroprocessing operations. Studies were performed to acquire information on the effect of high levels of ZSM-5 additive on light olefins and gasoline composition in FCC.289 It was found that ZSM-5 can substantially increase propylene and butenes, and... 

Calcined LDHs also have application in the reduction of SOx and NOx emissions from the fluid catalytic cracking (FCC) units in oil refineries [194-196], Corma et al. attempted to optimize the performance of mixed oxides produced from MgAl-LDHs as SOx-removal additives to FCC catalysts [194]. Among the oxides studied, that obtained from a MgCuAl-LDH was found to be the most effective at catalysing both the oxidation of S02 to SO2 in the FCC regenerator and the reduction of the sulfates to H2S, which may be recovered,... 

The intake of fluoride as a constituent of substances described in FCC monographs, even at the maximum limits established for fluoride, is not expected to significantly add to the human daily fluoride intake from other sources and is well within the various limits described in the Institute of Medicine s committee report. Nonetheless, given that toxicological manifestations have been amply demonstrated for fluoride, as described in the report, the maintenance of fluoride limits in drinking water and food, and thus food additives, appears consistent with sound public health policy. Therefore, the Committee on Food Chemicals Codex considers that maintaining fluoride limits for relevant food additives and ingredients is justified. 

In addition to FCC labeling requirements, substances included in the Food Chemicals Codex are subject to compliance with such labeling requirements as may be promulgated by government bodies. Such substances are intended for use in foods, either directly or indirectly, and in food processing. 

Table 4.8 shows the shifts in product yields that can be realized with RxCat technology relative to traditional FCC, with an equal level of ZSM-5 additive in both reactors. The RxCat gasoline yield is 0-0.5 wt-% higher than the gasoline yield from a traditional FCC unit, and the olefin content of RxCat gasoline is 25% lower. The yields of LPG and light olefins increase, and the yields of heavy products decrease. 

RxCat technology continues the 50-year historical extension of improvements in FCC technology, with gasoline olefin reduction as an additional measure of efficiency. 

The increase of 1 unit of the RON corresponds to about 900.000 US per year for a 300.000 tpa hydroisomerization unit (1). In Figure 7.1, several major refinery processes to improve RON are shown these include isomerization, reforming, addition of FCC-Naphtha, alkylation, addition of oxygenates or polygas or butanes. The effect of these options with respect to the new specifications is different for each particular process. Keeping in mind the Californian ban on MTBE and also the fact... 

Lee et al. [29] reported the effect of PS addition in the catalytic degradation of waste HDPE and PS mixture using spent FCC catalyst at 400°C. Figure 5.14 shows the cumulative amount distributions of liquid products as a function of reaction time for the catalytic degradation of waste HDPE and PS mixture in different proportions. The increase of PS content in HDPE and PS mixture showed much high initial degradation rate and high... 

---