Distribution of Iron on FCC Catalyst and Its Effect on Catalyst Performance

The effects of different iron contamination content on the formation of iron nodules and the performance of FCC catalysts have been studied by cyclic deactivation treatment using iron naphthenate. The catalysts were characterized by X-ray diffraction, N2 adsorption-desorption, and SEM. The catalysts’ performance was evaluated by the Advanced Cracking Evaluation device. It has been found that there will be obvious nodulation on the catalyst when the iron concentration exceeds 7,400 μg/g. With the iron deposition from 53 μg/g to 11,690 μg/g, the crystal structure of zeolite will not be destroyed by iron. The surface area and pore volume of the catalyst decreased significantly; the surface area decreased from 125.3 m2/g to 91.0 m2/g, and the pore volume decreased from 0.21 cm3/g to 0.16 cm3/g. The studies also showed that the increase of iron deposition will lead to the decrease of catalytic reaction efficiency. With the iron deposition from 53 μg/g to 11,690 μg/g, the conversion decreased by 4.83%. Under the same 78 wt.% conversion, bottoms yield and coke yield increased by 2.15% and 1.31%, while gasoline yield and LCO yield decreased by 2.59% and 2.16%, respectively. The real state of the industrial iron contaminated equilibrium catalyst can be mimicked by using the cyclic deactivation method.

A Novel Method to Investigate the Activity Tests of Fresh FCC Catalysts: An Experimental and Prediction Process from Lab Scale to Commercial Scale

The issues of feedstocks, product markets, and environmental emissions have continuously proposed a number of challenges for industrial evaluation of fresh fluid catalytic cracking (FCC) catalyst before its application in commercial units. In this work, a convenient method was proposed by comparing with the existing commercial equilibrium catalyst. A series of laboratory experiments for steam treatments and microactivity tests were established to collect reliable data, and the standalone catalyst or co-catalysts were assessed to show the evaluation process and the predicted unit performance. The results had deviation, but a consistent yield distribution than that of a commercial equilibrium catalyst. These evaluations and predictions would provide us with not only the view of hydrothermal stability and yield distribution at the unit level, but also the economic potential for fresh catalyst based on the existing industrial catalyst, which will provide refiners with industrial basis for further decisions.

A Comparison of Laboratory Simulation Methods of Iron Contamination for FCC Catalysts

Two different methods of simulating iron contamination in a laboratory were studied. The catalysts were characterized using X-ray diffraction, N2 adsorption–desorption, and SEM-EDS. The catalyst performance was evaluated using an advanced cracking evaluation device. It was found that iron was evenly distributed in the catalyst prepared using the Mitchell impregnation method and no obvious iron nodules were found on the surface of the catalyst. Iron on the impregnated catalyst led to a strong dehydrogenation capacity and a slight decrease in the conversion and bottoms selectivity. The studies also showed that iron was mainly in the range of 1–5 μm from the edge of the catalyst prepared using the cycle deactivation method. Iron nodules could be easily observed on the surface of the catalyst. The retention of the surface structure in the alumina-rich areas and the collapse of the surface structure in the silica-rich areas resulted in a continuous nodule morphology, which was similar to the highly iron-contaminated equilibrium catalyst. Iron nodules on the cyclic-deactivated catalyst led to a significant decrease in conversion, an extremely high bottoms yield, and a small increase in the dehydrogenation capacity. The nodules and distribution of iron on the equilibrium catalyst could be better simulated by using the cyclic deactivation method.

The reduction of FCCU afterburning through process optimization and regenerator revamping

Operating the fluid catalytic cracking unit (FCCU) in afterburning conditions can increase the regenerator temperatures above the metallurgical design leading to mechanical failures of the cyclones and plenum chamber. This paper presents the methodology applied in a commercial FCCU to investigate the afterburning causes and the technical solutions that can be implemented to reduce the afterburning. Thus, by evaluating the regenerator temperature profile, regenerator as-build design and the internals mechanical status, it was concluded that the main cause of afterburning was the non-uniform distribution and mixing of air and catalyst. The industrial results showed that optimizing the catalyst bed level, stripping steam, reaction temperature and equilibrium catalyst (e-cat) activity reduced the afterburning by 39%. Other process parameters such as feed preheat temperature, slurry recycling and excess oxygen did not have a significant influence on afterburning because of air and catalyst maldistribution. Revamping the regenerator to assure a symmetrical layout of cyclones reduced the afterburning by 86%, increased the fines retention in FCCU inventory and provided a better regeneration of the spent e-cat. The reduction of operating temperatures at around 701?C removed the risk of catalyst thermal deactivation and therefore the e-cat activity was increased by 10.2 wt.%.