Fluid catalytic cracking performance

Zeolite ZSM-5 in Fluid Catalytic Cracking Performance, Benefits, and Applications... 

A great need exists for reliable Fluid Catalytic Cracking performance tests which can be used for the evaluation of feedstocks and catalysts. 

Catalytic cracking is a process that is currently performed exclusively over fluidized catalyst beds. The fluid catalytic cracking (FCC) process was introduced in 1942 and at that time replaced the conventional moving bed processes. These early processes were based on acid-treated clays as acidic catalysts. The replacement of the amorphous aluminosilicate catalysts by Faujasite-type zeolites in the early-1960s is regarded as a major improvement in FCC performance. The new acidic catalysts had a remarkable activity and produced substantially higher yields than the old ones. 

The first cracking catalysts were acid-leached montmorillonite clays. The acid leach was to remove various metal impurities, principally iron, copper, and nickel, that could exert adverse effects on the cracking performance of a catalyst. The catalysts were first used in fixed- and moving-bed reactor systems in the form of shaped pellets. Later, with the development of the fluid catalytic cracking process, clay catalysts were made in the form of a ground, sized powder. Clay catalysts are relatively inexpensive and have been used extensively for many years. 

The desire to have catalysts that were uniform in composition and catalytic performance led to the development of synthetic catalysts. The first synthetic cracking catalyst, consisting of 87% silica (Si02) and 13% alumina (AI2O3), was used in pellet form and used in fixed-bed units in 1940. Catalysts of this composition were ground and sized for use in fluid catalytic cracking units. In 1944, catalysts in the form of beads about 2.5 to 5.0 mm in diameter were introduced and comprised about 90% silica and 10% alumina and were extremely durable. One version of these catalysts contained a minor amount of chromia (Cr203) to act as an oxidation promoter. 

A number of mechanistic modeling studies to explain the fluid catalytic cracking process and to predict the yields of valuable products of the FCC unit have been performed in the past. Weekman and Nace (1970) presented a reaction network model based on the assumption that the catalytic cracking kinetics are second order with respect to the feed concentration and on a three-lump scheme. The first lump corresponds to the entire charge stock above the gasoline boiling range, the second... 

The fluid catalytic cracking process using vacuum gas oil feedstock was introduced into the refineries in the 1930s. In recent years, because of a trend for low-boiling products, most refineries perform the operation by partially blending... 

Uygun, H. Ta kin, C. Kubat, and S. Arslankaya, FUZZYFCC Fuzzy logic control of a fluid catalytic cracking unit (FCCU) to improve dynamic performance, Computers Chemical Engineering, 30(5), 850-863 (2006). 

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,... 

Fluid coking and fluid catalytic cracking (FCC) are mechanically similar The products of fluid coking and delayed coking are the same (i.e., coke and distillate products), but the equipment is physically different. Alkylation of the three- and four-carbon molecule products from these units is commonly performed to convert them to branched chain gasoline, which increases the octane rating. As can be seen from Figure 1.1 in Chapter One, the feed to fluid catalytic crackers is a gas-oil distillate. For delayed cokers and fluid cokers, the feed is residium. 

PCA and its performance is illustrated using the fluid catalytic cracking unit (FCCU) challenge problem [193]. 

An important example are alumina-supported Co—Mo and Ni—Mo sulfides, which constitute the active phases in catalysts for hydrotreating of middle distillates (403). It appears that in such catalysts, mostly pseudoboehmite-derived Y-AI2O3 is used as the support. According to fiter-ature data, catalysts for fluid catalytic cracking (FCC) gasoline desulfurization, which is performed at 260—340 °C and 5—30 atm, may contain 5—11 wt% molybdenum and 2-3 wt% cobalt supported on AI2O3 with a surface area of220—240 w (405). Catalysts for diesel fuel desulfurization to low-sulfur... 

Apart from the oxidation of organic molecules, the catalytic pyrolysis of waste tires to light olefins using mesoporous material containing metals was also performed. Generally, the production of light olefins has been derived mostly from steam crackers and refinery fluid catalytic cracking units. Moreover, their demand... 

A series of experiments varying temperature, micro-sphere size and time on stream have been performed in a fixed fluidised bed microactivity reactor to study the role of intraparticle diffusion in commercial fluid catalytic cracking (FCC) catalysts, particularly on gasoline yield and catalyst deactivation by coke deposition, for the cracking of a vacuum gas oil. Additionally, a mechanistic model that describes interface and intrapartide mass transfer interactions with the cracking reactions, has been used to study the combined influence of pore size and intraparticle mass diffusion on the deactivation of FCC catalysts and the gasoline yield. 

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