Catalytic cracking of naphtha: The effect of Fe and Cr impregnated ZSM-5 on olefin selectivity

Abstract

This study focuses on the modification of ZSM-5 in order to enhance the catalytic cracking of refinery naphtha to produce light olefins. ZSM-5 was metal modified using different loadings (0.5-5 wt%) of Fe and Cr via the impregnation method. The metal modified ZSM-5 samples are compared and the effect of metal loading on the physicochemical properties and catalytic performance is investigated. Fe and Cr modification had an effect on both the physicochemical properties of the catalysts as well as catalytic activity and selectivity. Metal loading caused a decrease in the specific surface area which decreased further with increased metal loading. Fe had a greater effect on the total acidity in particular strong acid sites when compared to Cr. The optimum Fe loading was established which promoted selectivity to olefins, in particular propylene. Fe also had a dominant effect on the P/E ratio of which a remarkable ratio of five was achieved as well as enhanced the stability of the catalyst. Cr was found to be a good promoter for selectivity to BTX products with a two-fold increase observed when compared to Fe-modified catalysts.

Aromatik Karışımların Hidrodealkilasyonuna Katalizör Modifikasyonun Etkisi

“…The other production method of BTX is the hydrodealkylation of C9+ aromatics in the presence of a variety of catalysts such as metal oxides and zeolite catalysts [4][5][6][7]. Among studied catalysts, chrome-based catalysts are the most promising catalyst and mostly used in commercial processes [8,9]. Hydrodealkylation of alkyl-aromatics over Cr2O3/Al2O3 is carried under high hydrogen atmosphere (60-70 10 5 Pa) at high temperatures (T> 600 o C) in order to removal of methyl groups on aromatic rings.…”

The effect of water and zinc loading on LPG catalytic cracking for light olefin production using Response Surface Methodology

“…Light olefins, propylene and ethylene, are among the largest volumes of petrochemicals, which account for a significant portion of the market demand in the world [1][2][3][4][5]. Due to the limitation of thermal cracking in controlling the olefin product, feed dependence and the global concern about high operating temperatures, catalytic cracking has been taken into account as a traditional method of producing light olefin to overcome the quoted deficiencies [6][7][8].…”

Modified Acid‐Base ZSM‐5 Derived from Core‐Shell ZSM‐5@ Aqueous Miscible Organic‐Layered Double Hydroxides for Catalytic Cracking of n‐Pentane to Light Olefins

“…To overcome these drawbacks, zeolite catalysts have been modified by several approaches, for example, the creation of the additional mesoporosity in zeolite frameworks [12,13,14,15] as well as the modification with rare earth and metals, such as metal oxides and alkaline-earth metals. [16,17,18,19] However, there is the limitation of an excessive number of strong Brønsted acid sites on external surfaces of zeolites, leading to competing hydride transfers and further side reactions, such as oligomerization, isomerization, cyclization, and aromatization. [20,21] To deal with these issues, the modification of external acidity of zeolites has been investigated.…”

“…However, it often suffers from some disadvantages, such as, a short catalyst lifetime, and a very low yield of light olefins. To overcome these drawbacks, zeolite catalysts have been modified by several approaches, for example, the creation of the additional mesoporosity in zeolite frameworks as well as the modification with rare earth and metals, such as metal oxides and alkaline‐earth metals . However, there is the limitation of an excessive number of strong Brønsted acid sites on external surfaces of zeolites, leading to competing hydride transfers and further side reactions, such as oligomerization, isomerization, cyclization, and aromatization .…”