Amorphous silica-alumina as robust support for catalytic dehydrogenation of propane: Effect of Si/Al ratio on nature and dispersion of Cr active sites

Karam, Hamid; Soltanali, Saeed; Najafi, Amir Mohammad; Ghazimoradi, Maryam; Yaghoobpour, Elham; Abbasi, Ali

doi:10.1016/j.apcata.2023.119167

Cited by 10 publications

(3 citation statements)

References 49 publications

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“…Among the methods studied, because of the high surface area and adsorption capacity, energy-saving and low capital cost needs of these adsorbents, sorption on solids, particularly by zeolites, has grabbed the attention of researchers. − The most common industrial method for CO 2 adsorption utilizes dry solid sorbents after fossil fuel combustion. Zeolites are regarded as promising CO 2 adsorbents due to their tunable porous structure, which allows them to overcome molecule diffusion limitations.…”

Section: Introductionmentioning

confidence: 99%

Equilibrium and Kinetic Insights into the Comprehensive Investigation of CO₂, CH₄, and N₂ Adsorption on Cation-Exchanged X and Y Faujasite Zeolites

Najafi,

Khorasheh,

Soltanali

et al. 2023

Langmuir

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The adsorption equilibria and kinetic performance of CO 2 , CH 4 , and N 2 on pelletized cation-exchanged faujasite zeolites (with alkali, alkaline earth, and transition metal ions) have been investigated by an innovative volumetric apparatus simultaneously. The standard instrumental analytical techniques, including X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy (EDX), and atomic absorption spectroscopy (AAS), were utilized to characterize binder-free modified zeolites. EDX and AAS analyses revealed that the ion exchange was successfully achieved. The results indicate that the type of cation present in the zeolite framework and the Si/Al ratio can have a significant impact on the adsorption capacity and kinetic performance. The obtained isotherms were determined by three isotherm models, and the Langmuir−Freundlich (Sips) model was found to show the best agreement with the experimental isotherm data for all gases. The CO 2 uptakes of KX, MgX, and CaX reached 4.13, 4.79, and 5.48 mmol/g, respectively. The effective binary and kinetic selectivities of CO 2 /CH 4 and CO 2 /N 2 were also calculated. Among all samples, KX showed the highest CO 2 /CH 4 and CO 2 /N 2 selectivities of 54.46 and 91.62, respectively. Pseudo-first-, pseudo-second-order, and Avrami kinetic models were fitted to the experimental kinetic data to analyze the adsorption kinetics. Finally, the macropore diffusion coefficient (D p ) and microporous diffusional time constant (D c /r c 2 ) were estimated by correlating the micropore−macropore kinetic model with the experimental fractional uptake curves. Among the ion-exchanged zeolite samples, the K + form exhibits a suitable performance in terms of kinetic behavior and adsorption capacity.

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Section: Introductionmentioning

confidence: 99%

Equilibrium and Kinetic Insights into the Comprehensive Investigation of CO₂, CH₄, and N₂ Adsorption on Cation-Exchanged X and Y Faujasite Zeolites

Najafi,

Khorasheh,

Soltanali

et al. 2023

Langmuir

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“…Chemical groups and bonds in the substance are identied using FTIR spectroscopy. 29,30 The FTIR spectrum of Z40, Z80, and Z120 samples is shown in Fig. 3 FTIR vibrations can be classied into two categories: internal vibrations and external vibrations.…”

Section: Resultsmentioning

confidence: 99%

The effect of Si/Al ratio of ZSM-12 zeolite on its morphology, acidity and crystal size for the catalytic performance in the HTO process

Soltani,

Zamaniyan,

Darian

et al. 2024

RSC Adv.

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“…In general, the first peak could be attributed to the reduction of chromium species in high oxidation states to Cr(III), while the second corresponds to the reduction of Cr(III) to Cr(II) species [20]. Recent studies also suggest the existence of Cr(III) in two distinctive environments, with Cr 2 O 3 present either as crystallites or as grafted species (less reducible) [21].…”

Section: Physicochemical Properties Of Catalystsmentioning

confidence: 99%

Metal-Doped HZSM-5 Zeolite Catalysts for Catalytic Cracking of Raw Bio-Oil: Exploring Activity toward Value-Added Products

et al. 2023

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Catalytic cracking of bio-oil, conducted at atmospheric pressure without hydrogen supply, is a cost-effective and versatile approach for the targeted synthesis of biofuels and platform chemicals. The conversion of raw bio-oil follows intricate reaction pathways strongly influenced by the catalyst properties. In this work, we explore the use of various transition metals (Cr, Fe, and Zn) to modify the properties of HZSM-5 zeolite and assess their impact on the catalytic cracking of real raw bio-oil feedstock. The effect of metal loading on physical and chemical characteristics of metal-doped zeolite catalysts was studied through XRD, XRF, N2 physisorption, NH3-TPD, FTIR, H2-TPR. The behavior of each catalyst was evaluated in a continuous two-step catalytic cracking system (TS-CC) operating at 450 °C and space-time 0.7 gcatalysth/gfeed. The results highlight the importance of carefully selecting active metal species to optimize the performance of HZSM-5 in the catalytic cracking of bio-oil. Cr and Fe were found to be effective metals in increasing the selectivity of C2–C4 olefins in the gas product and mono-aromatics in the hydrocarbon liquid product, whereas the Zn-doped catalyst exhibits poor activity compared to bulk zeolite. Furthermore, a significant impact of the metal oxidation state on catalytic activity was observed, with reduced metals promoting the formation of H2, CO, and CO2 at the expense of hydrocarbon production.

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Amorphous silica-alumina as robust support for catalytic dehydrogenation of propane: Effect of Si/Al ratio on nature and dispersion of Cr active sites

Cited by 10 publications

References 49 publications

Equilibrium and Kinetic Insights into the Comprehensive Investigation of CO₂, CH₄, and N₂ Adsorption on Cation-Exchanged X and Y Faujasite Zeolites

Equilibrium and Kinetic Insights into the Comprehensive Investigation of CO₂, CH₄, and N₂ Adsorption on Cation-Exchanged X and Y Faujasite Zeolites

The effect of Si/Al ratio of ZSM-12 zeolite on its morphology, acidity and crystal size for the catalytic performance in the HTO process

Metal-Doped HZSM-5 Zeolite Catalysts for Catalytic Cracking of Raw Bio-Oil: Exploring Activity toward Value-Added Products

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Amorphous silica-alumina as robust support for catalytic dehydrogenation of propane: Effect of Si/Al ratio on nature and dispersion of Cr active sites

Cited by 10 publications

References 49 publications

Equilibrium and Kinetic Insights into the Comprehensive Investigation of CO2, CH4, and N2 Adsorption on Cation-Exchanged X and Y Faujasite Zeolites

Equilibrium and Kinetic Insights into the Comprehensive Investigation of CO2, CH4, and N2 Adsorption on Cation-Exchanged X and Y Faujasite Zeolites

The effect of Si/Al ratio of ZSM-12 zeolite on its morphology, acidity and crystal size for the catalytic performance in the HTO process

Metal-Doped HZSM-5 Zeolite Catalysts for Catalytic Cracking of Raw Bio-Oil: Exploring Activity toward Value-Added Products

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Product

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About

Equilibrium and Kinetic Insights into the Comprehensive Investigation of CO₂, CH₄, and N₂ Adsorption on Cation-Exchanged X and Y Faujasite Zeolites

Equilibrium and Kinetic Insights into the Comprehensive Investigation of CO₂, CH₄, and N₂ Adsorption on Cation-Exchanged X and Y Faujasite Zeolites