Yield of products from catalytic cracking of vacuum gasoils

Abstract

In catalytic cracking of vacuum gasoils, the yields of products are correlated with their hydrogen content. A correlation that allows predicting the yields of products of this process was elaborated based on the results of cracking of 11 gasoils of different origin and data on their density, refractive index, and 50% distillation temperature. However, it is not possible to predict the octane number of the naphtha obtained in cracking with the group hydrocarbon composition of the feedstock.Feedstock consumption is one of the most important factors that determine an oil company's profitability.For this reason, feedstock of the optimum composition and quality must be selected for each oil refinery (OR). The cost of the feedstock for each given process is also determined by these parameters, particularly the content of light cuts.The quality of the feedstock cuts going to conversion units -catalytic cracking, hydrocracking, visbreaking, coking, etc., is due to the degree of their conversion into products of higher cost. The efficiency of catalytic cracking is inarguably one of the most important processes in oil refining and is basically a function of the chemical nature of the feedstock. According to the mass spectroscopic data in [1] obtained in conversion of nine vacuum gasoils, the yield of naphtha cut is maximum, and the yields of other products are correlated with the alkane, cycloalkane, and monocyclic arene content in the feedstock. It was later shown in [2] that the quality of catalytic feedstock can be evaluated by empirical methods based on the data from regularly performed analyses. We quantitatively evaluated the quality of vacuum gasoils from different crudes as catalytic feedstock.The physicochemical characteristics of these gasoils are reported in Table 1. The molecular weight and hydrogen 312 content were determined with the density, refractive index, and 50% distillation temperature in simulated distillation with the correlations reported in [3,4].The experiments were conducted on a MAT (Micro Activity Test) laboratory unit with the method in ASTM D 3907-92. The conversion was varied by varying the catalyst:feedstock mass ratio from 2 to 6. The methodology of the experiments is described in detail in [2]. The feedstock was cracked in an equilibrium industrial catalyzer with the following physicochemical properties: Chemical composition, wt. % Al 2 O 3 47.2 Na 2 O 0.17 Re 2 O 3 1.34 Metal content vanadium, ppm 1074 nickel, ppm 328 iron, wt. % 0.68 Microactivity: conversion, wt. % 71 Average particle size, mm 71 Bulk density, kg/m 3 920Pore volume, cm 3 /g 0.3 Total specific surface area, m 2 /g 66The necessity of comparing different feedstock at the maximum yield of naphtha cut was demonstrated in [1]. A comparison at constant conversion or constant yield of coke cannot be conclusive, since each feedstock has its own optimum degree of conversion.The feedstock was cracked at different catalyst:feedstock ratios and constant (30 sec) contact time of the catalyst with the feedstock. The possibility of us...

Catalytic Cracking of Diverse Vacuum Residue Hydrocracking Gas Oils

“…Over the years, laboratory fixed-bed, fluid-bed, and circulating-riser units have been used to evaluate the effect of feedstock quality on the FCC process performance [14][15][16][17][18][19][20][21][22][23][24][25]. Different characteristics of the studied feeds, employing distinct techniques for characterization, have been correlated with crackability or extent of conversion for a given set of operating conditions.…”

Performance of Equilibrium FCC Catalysts in the Conversion of the SARA Fractions in VGO

“…It could be expected that the coke formed from the aromatic AF and resin RF fractions would deposit more preferentially on the external surface area of the zeolite crystals or the matrix, given the more restricted accessibility of their molecules to the inner acidic sites of the zeolite. 62 The comparison between the catalysts shows that the losses of…”

“…It could be expected that the coke formed from the aromatic AF and resin RF fractions would deposit more preferentially on the external surface area of the zeolite crystals or the matrix, given the more restricted accessibility of their molecules to the inner acidic sites of the zeolite. 62 The comparison between the catalysts shows that the losses of acidity per mass unit of coke produced were more noticeable in the case of catalyst ECAT-D than in catalyst ECAT-R. Once again, this behavior suggests that, at the same degree of conversion, catalyst ECAT-R is less affected by the coke deposition in comparison to catalyst ECAT-D, which contains a higher proportion of strong acidic sites, inducing a stronger adsorption of coke precursors and coke itself. Bronsted and Lewis acid sites in the catalysts may interact differently with coke precursors and the end coke product.…”

Empirical Models to Characterize the Structural and Physiochemical Properties of Vacuum Gas Oils with Different Saturate Contents

“…The performance of these processes has been shown in many studies to strongly depend on the quality of the feedstock [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. The vacuum gas oil fraction from petroleum is the typical feed for the FCC [2,3,[5][6][7][8][9][10][11][12][13][14][15][16][17] and it has been explored as a feedstock for steam cracking as well [4]. Considering that in Resources 2021, 10, 71 2 of 20 both FCC and thermal cracking the reactivity of the vacuum gas oils increases with the saturate content enhancement and aromatic carbon content reduction, the information about these vacuum gas oil characteristics is of paramount importance for optimizing their performance [17].…”