Review on the Catalytic Conversion of Naphtha to Aromatics: Advances and Outlook

Akhtar, M. Naseem; Aitani, Abdullah M.; Ummer, Aniz Chennampilly; Alasiri, Hassan

doi:10.1021/acs.energyfuels.2c03716

Cited by 20 publications

(5 citation statements)

References 164 publications

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“…The metalmodified MFI catalysts exhibit bifunctionality due to the existence of Brønsted acid sites attributed to the zeolite structure and Lewis acid sites from metals having inadequate electrons. The aromatization of propane involves a series of reactions at both acid sites within the catalysts [39]. The Brønsted acid sites are typically associated with cracking, oligomerization, isomerization, and cyclization reactions, while the Lewis acid sites play a role in dehydrogenation reactions.…”

Section: Effect Of Si/(al+ga) Ratiomentioning

confidence: 99%

Transformation of Light Alkanes into High-Value Aromatics

Akhtar

2024

Catalysts

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This research work is focused on the transformation of light alkane (propane) into high-value aromatics using gallo-alumino-silicate catalysts. Two sets of gallo-alumino-silicates were synthesized for this study. In the first set, the ratio of Ga/(Al+Ga) was modified, while the Si/(Al+Ga) ratio was held constant. In the subsequent set, the Si/(Al+Ga) ratio was adjusted, while maintaining a consistent Ga/(Al+Ga) ratio. This approach aimed to directly assess the impact of each ratio on catalyst performance. The comprehensive characterization of all catalysts was conducted using various instrumental techniques, i.e., BET surface area, XRD, NH3-TPD, 27Al, 71Ga and 29Si MAS NMR, and XPS. A gradual reduction in the percentage of crystallinity and rise in meso-surface area was noticed with a rise in Ga/(Al+Ga) ratio. The total acidity (NH3-TPD) demonstrated a decline as the Si/(Al+Ga) ratio increased, attributed to an overall decline in Al3+ or Ga3+ species. The XPS intensity of the Ga 2p3/2 peak rose in correlation with an elevated ratio of Ga/(Al+Ga), suggesting the formation of extra-framework Ga species. The propane conversion, aromatic yield, and aromatization/cracking ratio exhibited an increase with an increasing Ga/(Al+Ga) ratio, reaching an optimum value of 0.46 before declining. Conversely, an appreciable drop in the conversion of propane and yield of aromatics was detected with the rise in Si/(Al+Ga) ratio, attributing to the decline in acidity. The catalyst having a Ga/(Al+Ga) ration of 0.46 exhibited the highest propane conversion and aromatic yield of 83.0% and 55.0% respectively.

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Section: Effect Of Si/(al+ga) Ratiomentioning

confidence: 99%

Transformation of Light Alkanes into High-Value Aromatics

Akhtar

2024

Catalysts

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“…A few studies using commercial feeds are available in the literature in reforming, including our study on the effect of pore-modified ZSM-5 catalysts 3 and our recent review on aromatization of naphtha. 4 For a cost-effective commercial operation, this process requires selectivity enhancement. which are produced by cracking over the catalysts, and such studies are seldom reported in the literature.…”

Section: ■ Introductionmentioning

confidence: 99%

“…However, real commercial feed contains a large number of hydrocarbon components and their possible isomers, which makes the chemistry more complex. A few studies using commercial feeds are available in the literature in reforming, including our study on the effect of pore-modified ZSM-5 catalysts and our recent review on aromatization of naphtha . For a cost-effective commercial operation, this process requires selectivity enhancement.…”

Section: Introductionmentioning

confidence: 99%

Understanding the Promotional Effect of Silver in Naphtha Reforming over a Ga/ZSM-5 Catalyst to Enhance Liquid Yield

Ummer,

Akhtar,

Alnaimi

et al. 2024

J. Phys. Chem. C

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Aromatics are one of the most highly demanded hydrocarbon raw materials for the chemical industry. In the present study, efforts are made to understand the promotional effect of silver together with gallium on ZSM-5 zeolite as a catalyst for the reforming reaction of realistic, full range commercial naphtha feed in a fixed bed reactor at atmospheric pressure and 550 °C temperature. The dual metal system showed a synergic effect to enhance the aromatic selectivity and liquid yield and decrease the off-gas formation. The catalyst samples are prepared by desilication followed by co-impregnation of silver and gallium on to ZSM-5, characterized by X-ray diffraction, N 2 adsorption, NH 3 desorption, pyridine-FTIR, temperature-programmed reduction, and analysis of morphology. It is observed from reduction studies that upon incorporation of silver and gallium, catalyst properties like proton abstraction, reducibility, Lewis and Bronsted acidities, etc. are favorably modified. These results are discussed in detail, and an attempt is made to correlate them with the catalytic reaction results obtained.

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“…In recent years, various high-performance aromatization catalysts have been developed [ 9 , 10 ]. For instance, Zhou et al synthesized the Pt/KZSM-5 (deAl) catalyst through the ion exchange method, achieving aromatics selectivity of up to 75.4% and n -heptane conversion of 96.1% [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Exploring Deactivation Reasons of Biomass-Based Phosphorus-Doped Carbon as a Metal-Free Catalyst in the Catalytic Dehydroaromatization of n-Heptane

Yu,

Liu,

Liu

2024

Molecules

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Catalytic dehydroaromatization of n-alkanes into high-value aromatics has garnered extensive interest from both academia and industry. Our group has previously reported that phosphorus-doped carbon materials exhibit high selectivity for C-H bond activation in the dehydroaromatization of n-hexane. In this study, using n-heptane as a probe, we synthesized biomass-based phosphorus-doped carbon catalysts to investigate the impact of hydrogen heat treatment and carbon deposition on catalyst structure. Despite achieving an initial conversion of n-heptane at approximately 99.6%, with a toluene selectivity of 87.9%, the catalyst activity fell quickly. Moreover, longer hydrogen treatment time and higher hydrogen concentrations were found to accelerate catalyst deactivation. Thermogravimetric analysis (TGA) and N2 adsorption measurements (BET) indicated that a small amount of coke deposition was not the primary cause of catalyst deactivation. Temperature-programmed desorption of ammonia gas (NH3-TPD) revealed a significant decrease in acid-active functional groups. X-ray photoelectron spectroscopy (XPS) and solid-state 31P NMR spectroscopy confirmed the reduction of active central phosphorus species. These results suggest that catalyst deactivation primarily arises from the decrease in acidity and the partial reduction of phosphorus-containing groups, leading to a substantial loss of active sites. This work contributes new perspectives to understanding the properties and design improvements of metal-free carbon catalysts.

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Review on the Catalytic Conversion of Naphtha to Aromatics: Advances and Outlook

Cited by 20 publications

References 164 publications

Transformation of Light Alkanes into High-Value Aromatics

Transformation of Light Alkanes into High-Value Aromatics

Understanding the Promotional Effect of Silver in Naphtha Reforming over a Ga/ZSM-5 Catalyst to Enhance Liquid Yield

Exploring Deactivation Reasons of Biomass-Based Phosphorus-Doped Carbon as a Metal-Free Catalyst in the Catalytic Dehydroaromatization of n-Heptane

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