Performance of Ag-HZSM-5 Zeolite Catalysts in n-heptane Conversion

Asaftei, Iuliean Vasile; Lungu, Neculai Catalin; Birsa, M. L.; Sandu, Ioan Gabriel; Sarbu, Laura Gabriela; Ignat, M.

doi:10.37358/rc.17.1.5401

Cited by 14 publications

(30 citation statements)

References 10 publications

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“…Ni-HZSM-5 shows higher yields for aromatic hydrocarbons and H 2 than HZSM-5 because Ni 2+ cations catalyze the recombinative desorption of hydrogen atoms as H 2 , as it has been shown previously also for Zn 2+ cations [46,62]. This desorption step is not quasiecquilibrated during alkanes reactions on any these materials (HZSM-5, Ni-HZSM-5, Zn-HZSM-5) and catalytic sites provided by these cations remove the kinetic bottlenecks that limit the rate and selectivity of alkanes aromatization reactions [82].…”

Section: = Hydrocarbons Conversionsupporting

confidence: 60%

“…XRD powder pattern of the Na-ZSM-5 sample exhibit only diffraction lines proper to MFI structure high crystallinity. The pattern confirms that the synthesized zeolite has the structure identical to MFI-type zeolite [81][82][83][84][85][86]. The morphology and size of the individual crystals were obtained by scanning electron microscopy (SEM) with a Microspec WDX-2A using a 25 kV accelerating potential.…”

Section: Characterizationsupporting

confidence: 56%

“…Ni 2+ cations increase the reversibility of hydrogen adsorption-desorption steps. As in the case of zinc and gallium exchanged HZSM-5 zeolites these reactions appear to proceed via bifunctional pathways involving acid OH groups and exchanged metals cations [25,26,43,53,54,60,82].…”

Section: = Hydrocarbons Conversionmentioning

confidence: 97%

“…The morphology and size of the individual crystals were obtained by scanning electron microscopy (SEM) with a Microspec WDX-2A using a 25 kV accelerating potential. The SEM image of parent NaZSM-5 is presented in literature [83][84][85][86] revealsing the well-defined morphology of crystals indicating highly crystalline material.…”

Section: Characterizationmentioning

confidence: 99%

“…Low temperature peak correspond to less acidic sites (terminal OH groups, cationic sites M z+ , AlO + ). The temperature and the amount of desorbed ammonia give information about strength and number of the acid sites [42,3,55,58,62,[83][84][85][86].…”

Section: Characterizationmentioning

confidence: 99%

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Transformation of Gaseous Technical Mixture of the Alkanes and Alkenes Into Liquid Fraction Over Ni-HZSM-5 Obtained by Ionic Exchange

Asaftei¹,

Sandu²,

Lungu³

et al. 2018

Rev. Chim.

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Paraffin�s and olefins in the cracked naphtha can be transformed into aromatics and iso-paraffins to reduce the olefins content as well to improve the octane number of the gasoline commercial fraction. In this work Ni-HZSM-5 bifunctional catalyst was prepared by ion exchange with Ni(NO3)2 aqueous solution. The activity of Ni-HZSM-5 (wt.% 1.34% Ni) catalyst prepared by ion exchange method was investigated in the conversion of light hydrocarbons resulted as by-products of petroleum refining process (mixtures of butenes and (normal + iso) butanes as main components). The obtained Ni-based catalyst has been compare with HZSM-catalyst. The conversion experiments have been performed in a fixed-bed stainless-steel reactor (Twin Reactor System Naky) at 450oC, under 4 atm. (over Ni-HZSM-5) and 8 atm. pressure (over HZSM-5), respectively and at a space velocity (WHSV) of 1h-1. The catalytic activity of (Ni-HZSM-5 catalyst) monitored over 10 catalytic tests (with regeneration of catalyst after each test) using a mixtures butanes-butylenes. The catalytic activity and selectivity towards liquid products - BTX aromatic hydrocarbons and oligo(iC5-iC10, nC5-nC10, ] C10) - depends on time streaming, composition of butanes-butylenes mixture and pressure. In the first hours of each test the aromatic BTX are the main component of the liquid product (connected with butylenes consume) and after that, the oligo fraction become predominant. The initial aromatization process described as dehydrocyclodimerization of alkanes and alkenes, principally to aromatics BTX and molecular hydrogen, is accompanied by oligomerization, isomerization, cracking and alkylation processes to form finally in the liquid phase product an excessively mixture of iso- and normal - C5 -C10 and ] C10 aliphatic hydrocarbons.

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Section: = Hydrocarbons Conversionsupporting

confidence: 60%