Zeolite-based catalysts for the removal of trace olefins from aromatic streams
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ORIGINAL ARTICLE
Zeolite‑based catalysts for the removal of trace olefins from aromatic streams Jakkidi Krishna Reddy1 · Shruti Lad1 · Kshudiram Mantri1 · Jagannath Das1 · Ganesan Raman1 · Raksh Vir Jasra1 Received: 21 May 2020 / Accepted: 28 July 2020 © The Author(s) 2020
Abstract Removal of trace olefins from aromatic liquids was investigated on UZM-8 and MCM-22, which are the family of MWW zeolites. Both these zeolites were synthesized with similar Si/Al ratio and characterized by various techniques such as XRD, SEM, ICP, N2 adsorption, Ammonia TPD and solid-state MAS-NMR. Olefin conversion activity over UZM-8 was found to be significantly higher than that of MCM-22. In addition to this, deactivation of UZM-8 was slower than the MCM-22. UZM-8 with irregular stacking of MWW layers possess high external surface area and exposes more number of active sites to the reactant molecules. Mesopores generated due to the disordered layers of UZM-8 allows the fast diffusion of the substrate molecules in which pore clogging does not occur, thus making it more active and slow deactivation than that of MCM-22.
Activity under similar conditions UZM-8
MCM-22
Delaminated layers and Surface acid sites
Catalytic activity and Stability
Graphic abstract
External surface area/ Mesoporosity Keywords UZM-8 · MCM-22 · Olefin removal process and Structure activity correlationship
Introduction
* Jakkidi Krishna Reddy [email protected] 1
Reliance Technolgy Group, Reliance Industries Ltd., Vadodara Manufacturing Division, Vadodra, Gujarat 391346, India
In petroleum processing, aromatic streams which are used in various petrochemical processes are derived from naphtha reforming and thermal cracking. However, the aromatic streams derived from naphtha reforming and thermal cracking contains undesirable olefinic contaminants which will result into adverse effect on the post reformate hydrocarbon processes [1–3]. Olefinic material can affect the performance
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Applied Petrochemical Research
of downstream equipment, adsorbents and catalysts such as p-xylene recovery, xylene isomerization and disproportionation units. These impurities have tendency to oligomerize and form gums and other undesirable by-products which can foul heat transfer surfaces and reduce the efficiency of costly equipment and adsorbents/catalysts. Therefore, the hydrocarbon contaminants must be removed before subsequent processing of the aromatic streams. These detrimental trace olefins can be effectively removed via the acid-catalyzed alkylation of specific aromatics [4–6]. Conventionally, aromatics are refined by acid activated clays and zeolites-based catalysts in industrial plants. However, commercial clays have disadvantages such as poor regeneration performance, and rapid deactivation and environmental impacts due to solid disposal and land filling. Therefore, it is imperative to improve the process for purification of aromatics by developing easily synthesizable, stable and recyclable catalysts. Olefins removal is a process
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