Does hierarchical structure affect the shape selectivity of zeolites? Example of transformation of n-hexane in hydroisomerization

Effect of the nickel impregnation method on clay supports in the hydroconversion reaction of n-decane

Ni bifunctional catalysts supported on vermiculite, halloysite and bentonite previously modified by means of delamination or acid treatment were synthesized.

Value-Added Pyrolysis of Waste Sourced High Molecular Weight Hydrocarbon Mixtures

In this study, Fischer-Tropsch paraffin mixture, heavy residue of waste polyethylene pyrolysis, shredded and crashed agricultural polyethylene waste and their combinations were pyrolysed both thermally and catalytically in a two-stage reactor system. During the experimental work, yields and compositions of pyrolysis products were studied as function of feedstock composition and catalyst placement. It was found that the average molecular weight of feedstocks and the presence of ZSM-5 catalyst also have significant effects on the product yields and the compositions. Feedstocks with high concentration of Fischer-Tropsch paraffin and real waste polyethylene resulted in deeper fragmentation in both thermal and thermo-catalytic pyrolysis. Due to the deeper fragmentation, they seemed to be suitable feedstocks for the production of C6–C9 and C10–C14 hydrocarbons. Meanwhile, for production of C15–C21 hydrocarbons, the use of a higher concentration of heavy residue of waste polyethylene pyrolysis in the feedstocks is recommended. From the point of view of liquid hydrocarbon and isomer production, the placement of the catalyst into the 1st reactor proved to be more advantageous. When the catalyst was placed into the 2nd reactor, the product formation shifted to the more volatiles, isomers took part in secondary cracking reactions and aromatics formed in higher concentrations.

Mercaptosilane-assisted synthesis of highly dispersed and stable Pt nanoparticles on HL zeolites for enhancing hydroisomerization of n-hexane

Pt/HL-SH catalysts were synthesized by a facile mercaptosilane-assisted in situ synthesis approach and exhibited better catalytic performance in n-hexane hydroisomerization.

Enhanced dispersion of nickel nanoparticles on SAPO-5 for boosting hydroisomerization of n-hexane

The nickel based bifunctional catalyst with enhanced hydroisomerization performance was developed using an in-situ solid synthesis method. It was achieved to stabilize smaller Ni active sites on SAPO-5 using ethylenediaminetetraacetic acid (EDTA) ligands. The role of EDTA ligands was clarified by controlling the molar ratio of EDTA to Ni²⁺ (EDTA/Ni²⁺) over Ni/SAPO-5 catalysts. EDTA ligands inhibited the formation of nickel aluminate spinel and aggregation of NiO species during calcination, which dispersed Ni nanoparticles in a mean size of 4.7 nm on SAPO-5. The size of Ni nanoparticles could be controlled by regulating EDTA/Ni²⁺ ratio in [Ni-EDTA]^2- complex. The prepared catalyst exhibited high yield of isomers (54.0%) and di-branched isomers selectivity (18.0%) in the n-hexane hydroisomerization, which was approximately 2 times higher than that of the Ni/SAPO-5 catalyst without EDTA ligands at similar conversion. These results are important to propose a facile approach for the preparation of highly dispersed non-noble metal based bifunctional catalysts at a high loading.

Synthesis of hierarchical ZSM-5 nano-aggregated microspheres for application in enhancing the stability of n-hexane aromatization

Hierarchical ZSM-5 nano-aggregated microspheres were directly synthesized without any mesoporous templates and exhibited improved catalytic stability in n-hexane aromatization.

Study of CA-treated ZSM-22 zeolite with enhanced catalytic performance in the hydroisomerization of long-chain n-dodecane

Pt catalysts on citric acid treated ZSM-22 zeolites exhibited enhanced n-dodecane conversion (89.7%) and C₁₂-isomer yield (68.8%) compared with the parent ZSM-22 zeolite (19.6% and 16.4%).

New trends in tailoring active sites in zeolite-based catalysts

This review discusses approaches for tailoring active sites in extra-large pore, nanocrystalline, and hierarchical zeolites and their performance in emerging catalytic applications.