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

Yitao Liao,Xionghou Gao,Huihui Zhao,Tao Liu

doi:10.3390/catal11010104

Yitao Liao, Xionghou Gao + Show 2 more

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https://doi.org/10.3390/catal11010104

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Abstract

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.

Highlights

How to test a fluid catalytic cracking (FCC) catalyst’s performance and metal tolerance in the laboratory and calibrate the results to simulate the industrial performance is an ongoing discussion
Iron nodules are the main factor that leads to the poor performance of iron-contaminated catalysts
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 on a highly iron-contaminated equilibrium catalyst

Summary

Introduction

How to test a fluid catalytic cracking (FCC) catalyst’s performance and metal tolerance in the laboratory and calibrate the results to simulate the industrial performance is an ongoing discussion. Another important aspect of catalyst testing is the preparation of the catalyst [1]. In evaluating a fluid cracking catalyst’s performance in lab-scale testing, selecting the proper catalyst deactivation method is just as important as the testing itself [2]. It is difficult to accurately simulate the industrial heavy-metalpolluted equilibrium catalyst by selecting the laboratory deactivation protocols. With the increasing trend of heavy and poor-quality FCC feedstocks, the quantity and species of heavy metal deposition, such as

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