Thermal desorption of C6C9 n-alkenes from the surface of zeolite HY

Jasra, Raksh V.; Bhatt, B.D.; Garg, V.N.; Bhat, Sandeep

doi:10.1016/s0166-9834(00)80938-0

Cited by 6 publications

(4 citation statements)

References 8 publications

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“…Owing to its alkenyl side chain, eugenol molecules can potentially form coke on the zeolite surface beginning with the dimerization of eugenol. As this polymerization continues in parallel with reforming reactions, species including cycloalkenes, dienes, trienes, and aromatics could be formed [40,41]. These hydrogen-deficient species are usually formed in Table 2 Pseudo-first-order rate constants for the formation of abundant products produced in the reactions of eugenol catalyzed by HY zeolite Reaction number (keyed to Fig.…”

Section: Discussionmentioning

confidence: 99%

Upgrading of Lignin-Derived Compounds: Reactions of Eugenol Catalyzed by HY Zeolite and by Pt/γ-Al2O3

et al. 2011

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The conversion of eugenol (4-allyl-2-methoxyphenol), a compound derived from the lignin in woody biomass, was catalyzed by HY zeolite at 573 K and atmospheric pressure. The main products were isoeugenol and guaiacol, formed by isomerization and by deallylation, respectively. Substituted guaiacols with saturated sidechains (4-methylguaiacol, 4-ethylguaiacol, and 4-propylguaiacol) were also formed, by hydrogen transfer and alkylation reactions. The pseudo-first-order rate constant for the overall disappearance of eugenol was found to be 12.4 L (g of catalyst)/h. When the catalyst was Pt/c-Al 2 O 3 used in the presence of H 2 , significant hydrogenation of the propenyl side-chain took place, accompanied by isomerization, and hydrodeoxygenation. Under similar operating conditions, the reaction catalyzed by Pt/c-Al 2 O 3 in the presence of H 2 gave a higher eugenol conversion (X = 0.70) than the reaction catalyzed by HY zeolite (X = 0.11), primarily because of the dominant hydrogenation observed with the former catalyst. In the absence of H 2 as a co-reactant, the acidic c-Al 2 O 3 support in Pt/c-Al 2 O 3 evidently catalyzed all the classes of reactions catalyzed by HY zeolite.

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Section: Discussionmentioning

confidence: 99%

Upgrading of Lignin-Derived Compounds: Reactions of Eugenol Catalyzed by HY Zeolite and by Pt/γ-Al2O3

et al. 2011

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“…Temperature-programmed surface reaction studies of C 6 −C 9 olefins on HY using mass spectroscopy show the presence of dehydrogenated intermediates of aromatics; however, it was not determined if the intermediates were dienes/trienes or their cyclic analogues. 82 Studies in which n-hexane and n-heptane were converted over H-ZSM-5 at 683 K resulted in the production of C 1 −C 5 aliphatics as well as a significant yield of C 7 and C 8 aromatics (over 25 wt % for both reactants). 83 The presence of aliphatics smaller than the reactant indicates that alkane cracking is occurring simultaneously with cyclization reactions.…”

Section: Acs Catalysismentioning

confidence: 99%

“…In both of these routes, dehydrogenation occurs through hydrogen transfer reactions in which olefins or cycloalkanes donate hydrogen to other hydrocarbons that act as hydrogen acceptors. Temperature-programmed surface reaction studies of C 6 –C 9 olefins on HY using mass spectroscopy show the presence of dehydrogenated intermediates of aromatics; however, it was not determined if the intermediates were dienes/trienes or their cyclic analogues . Studies in which n -hexane and n -heptane were converted over H-ZSM-5 at 683 K resulted in the production of C 1 –C 5 aliphatics as well as a significant yield of C 7 and C 8 aromatics (over 25 wt % for both reactants) .…”

Section: Chemistry Of Mthmentioning

confidence: 99%

Mechanism of the Catalytic Conversion of Methanol to Hydrocarbons

2012

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The discovery of the dual aromatic- and olefin-based catalytic cycles in methanol-to-hydrocarbons (MTH) catalysis on acid zeolites has given a new context for rationalizing structure–function relationships for this complex chemistry. This perspective examines six major chemistries involved in the hydrocarbon pool mechanism for MTHolefin methylation, olefin cracking, hydrogen transfer, cyclization, aromatic methylation, and aromatic dealkylationwith a focus on what is known about the rate and mechanism of these chemistries. The current mechanistic understanding of MTH limits structure–function relationships to the effect of the zeolite framework on the identity of the hydrocarbon pool and the resulting product selectivity. We emphasize the need for assessing the consequences of zeolite structure in MTH in terms of experimentally measured rates and activation barriers for individual reaction steps and in terms of speciation preferences within the dual olefin- and aromatic-catalytic cycles to alter their relative propagation. In the absence of individual reaction rates, we propose using ethene/isobutane selectivity as a measure to describe the relative rates of propagation for the aromatic- and olefin-based cycles.

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“…Duringt he cyclization process, other reactions such as alkenes cracking, olefin dimerizationo ro ligomerization and aromatics alkylation may simultaneously occur.T his prevents acquiring experimental evidencef or clarifyingi fa lkene dehydrogenationo ccurs prior to cyclization or not. [24,25] Thus, some researchersm ade at ry to investigate dienesc yclization mechanism on H-ZSM-5 by calculating 1,5-and 1,6-cyclization pathways using embedded cluster. [26,27] It has been found that cyclization of dienes generated from alkenesd ehydrogenation is practicable.…”

Section: Introductionmentioning

confidence: 99%

Reaction Mechanism for Direct Cyclization of Linear C₅, C₆, and C₇ Alkenes over H‐ITQ‐13 Zeolite Investigated Using Density Functional Theory

Chen

Wei

et al. 2018

ChemPhysChem

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Although dienes or trienes have been shown to be possible precursors for cyclization, direct cyclization of alkenes or alkoxides has not been systematically studied yet. Thus, the reaction mechanism of cyclization of linear alkenes over H-ITQ-13 was investigated here by density functional theory considering dispersive interactions (DFT-D). The similar free energy of different linear alkoxides of the same carbon number suggests that they can co-exist in the H-ITQ-13 intersection at 673.15 K during the methanol to olefins (MTO) process. The formation of linear alkenes by olefins methylation with methoxyl groups (ZOCH ), trimethyloxonium ions (TMO ), and methanol are kinetically more favorable than by dimerization of olefins. Linear alkoxides or alkenes prefer direct cyclization to cycloalkanes rather than hydride transfer to diene. This study provides new insight into the alkene cyclization and aromatization mechanisms in MTO process.

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Thermal desorption of C6C9 n-alkenes from the surface of zeolite HY

Cited by 6 publications

References 8 publications

Upgrading of Lignin-Derived Compounds: Reactions of Eugenol Catalyzed by HY Zeolite and by Pt/γ-Al2O3

Upgrading of Lignin-Derived Compounds: Reactions of Eugenol Catalyzed by HY Zeolite and by Pt/γ-Al2O3

Mechanism of the Catalytic Conversion of Methanol to Hydrocarbons

Reaction Mechanism for Direct Cyclization of Linear C₅, C₆, and C₇ Alkenes over H‐ITQ‐13 Zeolite Investigated Using Density Functional Theory

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Thermal desorption of C6C9 n-alkenes from the surface of zeolite HY

Cited by 6 publications

References 8 publications

Upgrading of Lignin-Derived Compounds: Reactions of Eugenol Catalyzed by HY Zeolite and by Pt/γ-Al2O3

Upgrading of Lignin-Derived Compounds: Reactions of Eugenol Catalyzed by HY Zeolite and by Pt/γ-Al2O3

Mechanism of the Catalytic Conversion of Methanol to Hydrocarbons

Reaction Mechanism for Direct Cyclization of Linear C5, C6, and C7 Alkenes over H‐ITQ‐13 Zeolite Investigated Using Density Functional Theory

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Reaction Mechanism for Direct Cyclization of Linear C₅, C₆, and C₇ Alkenes over H‐ITQ‐13 Zeolite Investigated Using Density Functional Theory