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

Abstract

Over the past decades, the catalytic cracking catalysts for hydrocarbon oil upgrading have been extensively developed to increase the yield of light olefins. In this context, we report the fabrication of the core‐shell ZSM‐5@aqueous miscible organic‐layered double hydroxides prepared by the growth of layered double hydroxides (LDH) precursors on zeolite surfaces. The deposited LDH results in a decrease of the number of strong Brønsted acid sites on zeolite surfaces and its transformation at high temperature leads to produce the highly dispersed metal oxides deposited on external surfaces of zeolites. Therefore, the acid‐base properties of designed surfaces are modified, eventually resulting in the suppression of competing hydride transfers and further side reactions. As a result, there is a significant enhancement in light olefins production compared with the pristine zeolite. In addition, the designed catalysts exhibit high recycling stability and reusability. This first example opens up the new perspectives for the development of modified acid‐base zeolites using zeolite@aqueous miscible organic‐layered double hydroxides for the catalytic upgrading of hydrocarbons.

Core‐Shell Faujasite@Aqueous Miscible Organic‐Layered Double Hydroxides Composites with Tunable Acid/Base Properties for One‐Pot Synthesis of Ethyl trans‐α‐Cyanocinnamate

“…As expected, the isotherms of isolated FAU and LDHs exhibit type I and type IV, respectively, confirming the microporous structure and layered structure of zeolite and LDH, respectively. [ 16,41 ] Obviously, all the synthesized FAU@AMO‐LDHs composites possess the combination of type I and IV isotherms and the surface area is in the range between isolated FAU (541 m 2 g −1 ) and AMO‐LDHs (123 m 2 g −1 ), for example, 432 m 2 g −1 for the FAU@AMO‐LDHs‐15 composite. This again makes it clear that the combined features of FAU and LDHs were observed in case of the FAU@AMO‐LDHs composites.…”

“…The FAU@AMO-LDHs-x composites were prepared following the literature procedure with some modifications. [14,16] Typically, the solution of 0.05 m Mg(NO 3 ) 2 • 6H 2 O and 0.025 m Al(NO 3 ) 3 • 9H 2 O was prepared, and y mL (where y was 38, 96, and 192 mL) of prepared solution was subsequently dropped into a solution containing a 0.5 g of commercial FAU and a 0.052 m Na 2 CO 3 in a 100 mL of deionized water with a constant dropping rate. Then, the pH was adjusted by NaOH to obtain the pH of solution ≈10.…”

“…[ 15 ] Therefore, it can be noteworthy that one of the most promising materials for the acid‐base catalyst is a core‐shell zeolite@LDHs composite. [ 16 ]…”

“…[27,28] Moreover, compared with traditional multistep procedures for the production of ethyl trans-α-cyanocinnamate, the one-pot synthesis provides many advantages such as environmentally friendly management and the convenient process for separation and purification. [29] Although many bifunctional catalysts have been used in Knoevenagel cascade reaction, there are no reports using the designed core-shell zeolite@AMO-LDHs composite in this reaction even though it would combine the benefits between zeolites and AMO-LDHs, such as adjustable acid-base properties, [16] high surface area, [30] and dispersion of active sites. [31] Herein, we report the facile design of core-shell structured FAU@AMO-LDHs composites, containing FAU zeolite as a core and AMO-LDHs as a shell.…”

“…[15] Therefore, it can be noteworthy that one of the most promising materials for the acid-base catalyst is a core-shell zeolite@LDHs composite. [16] Among various promising basic catalysts, LDHs have been widely applied as solid base materials in a catalytic reaction. [17] In general, they are layered clay minerals, containing positively charged layers and interlayer anions.…”