Study on n-heptane Conversion Over Ni-HZSM-5 Zeolite Catalysts

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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.

Section: Characterizationsupporting

confidence: 58%

Section: Characterizationmentioning

confidence: 99%

Section: Characterizationmentioning

confidence: 99%

Section: = Hydrocarbons Conversionmentioning

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

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“…Ni-HZSM-5 and Ag-HZM-5 catalysts exhibit a good activity and selectivity towards BTX aromatics in conversion of light alkanes and alkenes [75][76][77][78][79][80][81][82][83][84][85][86][87].…”

mentioning

confidence: 99%

Performance of MFI Zeolite Catalysts in n-heptane Conversion Reaction Test

Asaftei¹,

Lungu²,

Sandu³

et al. 2018

Self Cite

The aromatization of n-heptane, one of the main components of light naphtha, has been investigated over HZSM-5 (Si/Al = 33.9) and Zn-HZSM-5: Zn1-HZSM-5 (0.86% Zn); Zn2-HZSM-5 (1.35% Zn) and Zn3-HZSM-5 (2.89% Zn) catalysts prepared by the ion exchange with 10M aqueous solution of Zn(NO3)2. The catalytic activity measurement was performed by the chromatographic pulse method in the temperature range of 673 - 823K. The presence of zinc in Zn-HZSM-5 catalysts provided a significant increase in total aromatics selectivity due to the improvement of dehydrogenation activity by Zn incorporation. The Zn species facilitated the aromatization by converting paraffin�s into corresponding olefins which, in turn, were the aromatics precursors. Therefore, both acidity and zinc incorporation played important roles in the aromatization of n-heptane. Over 773 K the activity and selectivity of the Zn-HZSM-5 catalysts decrease very probably due to the loss of zinc ions.

Evaluation of the Degree of Dental Anxiety in a Lot of Patients Altered in Young Adults

Raftu¹,

Sin²,

Caraiane³

et al. 2019

The study aims at identifying and highlighting dental anxiety in a group of young adults, analyzing patients� concerns about the main dental treatment procedures, and establishing statistical relationships between anxiety and gender, the background, level of education, socio-economic status and knowledge of habits of care and hygiene of oral cavity characteristic of the studied group. The study group consists of 150 female (50%) and male (50%) patients , aged between 20 and 40 years. The inclusion criteria in the batch were those related to the age range of 20 to 40 years.Two respondents (Corah�s Dental Anxiety Scale, Revised (DAS-R)) were given two questionnaires ( Corah�s Dental Anxiety Scale, DAS-R), and the second questionnaire contained 7 questions about the habits dental care). Most patients� concerns about the main procedures of dental treatment / other concerns are: dental extraction, material expenses, possibility of treatments and shame she felt oppressed health of the oral cavity. Regardless of the level of dental anxiety, the oral cavity hygiene habits are not properly performed by patients, with an increased tendency for them to be disregarded by patients with severe dental anxiety.