Catalytic cracking of large molecules over hierarchical zeolites

Abstract

A hierarchical zeolite catalyst was synthesized by transforming the skeletons of a bimodal pore silica gel into a zeolite through a steam-assisted conversion method, and shows high catalytic activity and a long catalyst lifetime for catalytic cracking of large molecules.

Synthesis of nanostructured catalysts by surfactant-templating of large-pore zeolites

“…It has been shown that the activity of zeolite based catalysts in this reaction is determined by the accessibility of BAS to the bulky TIPB molecules. 18,44 Our results demonstrate that the TIPB conversion increases on all zeolites following the mesostructuring treatment. The major liquid dealkylation products are 1,3-and 1,4-di-isopropylbenzenes for all the studied catalysts, and a small amount of mono-isopropylbenzene has been detected for both faujasites, which are the most active catalysts as they possess the more open pore systems with the largest pore apertures, and hence, the greatest number of accessible acid sites.…”

Zeolitic Materials with Hierarchical Porous Structures

“…[ 132 , 133 ] Sachse et al [ 132 ] and Lei et al [ 133 ] adopted the procedure of a pseudomorphic transformation of the silicon skeleton into ZSM-5. Arrays of TiO 2 -nanotubes have also been used by Schmuki et al [ 134 ] as a support for the zeolite formation.…”

Hydroisomerization of Emerging Renewable Hydrocarbons using Hierarchical Pt/H‐ZSM‐22 Catalyst

“…[12,[14][15][16][17][18][19] For example, the trimodal Y zeolite showed advantageous hydrocracking selectivity, [20] and the hierarchical ZSM-5 showed enhanced catalytic cracking of triisopropylbenzene. [21] The hierarchical ZSM-22, prepared by postsynthetic modifications of its parent (conventional) zeolite-preferably by desilication in alkaline medium followed by acid washing [22] proved to be a superior catalyst in the hydroisomerization of n-octane, attaining higher yields of branched products at the expense of cracking. [23] However, the vast majority of reports, including the latter study, have demonstrated the catalytic superiority of hierarchical zeolites only with relatively small model alkanes, such as linear C 4 -C 10 and xylenes, leaving the influence of the chain length and degree of branching of the reactants fully unexplored.…”