Comparison of Cresol Transformation on USHY and HZSM-5

Imbert, Freddy; Guisnet, M.; Gnep, S.

doi:10.1006/jcat.2000.2984

Cited by 16 publications

(13 citation statements)

References 22 publications

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“…temperature of 808 vs. 778 K for USY-P and ZSM-5-P, respectively). This illustrates that the medium sized micropores of ZSM-5-P prevent coke fouling superior to the large micropores of USY-P, in agreement with earlier reported results in cresol conversion over ZSM-5 and USY, and in other related reactions [57][58][59]. In conclusion, ZSM-5-P is the most effective (selective and stable) catalyst to dealkylate 4-EP into phenol and ethylene.…”

Section: Effect Of Pore Structure Of Zeolitessupporting

confidence: 92%

Shape selectivity vapor-phase conversion of lignin-derived 4-ethylphenol to phenol and ethylene over acidic aluminosilicates: Impact of acid properties and pore constraint

Liao

d’Halluin

Makshina

et al. 2018

Applied Catalysis B: Environmental

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Selective dealkylation of alkylphenols, the opposite reaction of the more commonly studied phenol alkylation, may represent an important reaction in the production of base chemicals like phenol and olefins from fossilized and raw lignocellulosic matter. This study reports the first thermodynamics and kinetics studies of the vaporphase conversion of ethylphenol (EP) over acidic γ-Al2O3, amorphous (ASA) and crystalline aluminosilicates (like ferrierite, ZSM-22, ZSM-5, beta, and USY) in the absence of hydrogen and noble metals, as a way to produce phenol and ethylene. The reaction was studied deliberately in presence of steam to get stable time on stream catalysis. The thermodynamic analysis shows an endothermal EP conversion to phenol and ethylene, favoured at high reaction temperature, while isomerisation, disproportionation and transalkylation are thermodynamically preferred at low temperature. The kinetic study examines the role of the catalytically active sites; it reveals the importance of site constraint on the activity, selectivity and stability, and shows the complex temperature dependency of the dealkylation. Both Brønsted and Lewis acid sites are active, but multifactor dependency (such as acid strength and site accessibility) complicates the establishment of simple quantitative relationships with the acid type. EP does not enter the micropores of ferrierite and ZSM-22, as suggested by adsorption experiments. Kinetics without significant diffusion limitations were obtained with ZSM-5, beta and USY. Thus, in absence of intracrystalline diffusion limitation (as verified by calculations using reported effective diffusivities, and substantiated by a comparably high apparent activation energy for all zeolites), the increased reaction turnover rate with increasing pore size from medium to large pore zeolites is largely explained by a change in reaction pathway (from monolecular to bimolecular) to convert EP to phenol and ethylene. A pathway proceeding through fast thermodynamically favourable bimolecular reactions occurs in the spatially non-constrained pores and crystal surface, whereas monomolecular reactions take place in the micropores of ZSM-5. Despite the lower rate, the selectivity over ZSM-5 strongly benefits from active site confinement, being responsible to achieve quantitative formation of phenol and ethylene from ethylphenol. The excellent performance of ZSM-5 thus accords with its shape selective property that avoids undesired side reactions such as the sterically demanding bimolecular reactions like disproportionation, transalkylation and CC cracking, and severe cokes formation.

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Section: Effect Of Pore Structure Of Zeolitessupporting

confidence: 92%

Shape selectivity vapor-phase conversion of lignin-derived 4-ethylphenol to phenol and ethylene over acidic aluminosilicates: Impact of acid properties and pore constraint

Liao

d’Halluin

Makshina

et al. 2018

Applied Catalysis B: Environmental

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“…The slower transalkylation consumes all three cresol isomers at practically the same rate (Figure 2). The resulting cresol isomer composition on the 12-member ring zeolite HBeta (o/p/m = 36:18:46) used in this work is similar to that reported on another 12-member ring zeolite, HY (o/p/m = 36:16:48), 31 even though their fine pore structures are different.…”

Section: Energy and Fuelssupporting

confidence: 80%

“…As a feedstock of industrial interest for manufacturing of antiseptics, drugs, insecticides, resins, antioxidants, and polymers, studies of the conversion of cresols over acid zeolites, such as HZSM-5 and HY, are available in the literature. − Zeolites are known to be effective in the conversion of methanol and other oxygenates to hydrocarbons, − and therefore, they have also been investigated for bio-oil upgrading. − …”

Section: Resultsmentioning

confidence: 99%

Efficient Conversion of m-Cresol to Aromatics on a Bifunctional Pt/HBeta Catalyst

et al. 2014

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The catalytic conversion of meta-cresol (3-methylphenol) was investigated over HBeta, Pt/SiO2, and Pt/HBeta catalysts at 400 °C and atmospheric pressure. The acid sites of zeolite HBeta catalyze methyl transfer reactions (isomerization and transalkylation), yielding cresol isomers (para- and ortho-cresol), dimethylphenol (xylenol) isomers, and phenol. Pt alone catalyzes hydrodeoxygenation and hydrogenation reactions, leading to toluene as the major product and methylcyclohexane as the minor product. Bifunctional Pt/HBeta catalyzes both methyl transfer reactions and hydrodeoxygenation reactions at the same time, producing toluene, benzene, and xylenes. The Pt/HBeta catalyst is about 10 times more active than the Pt/SiO2 catalyst toward hydrodeoxygenation, with a turnover frequency (on the basis of Pt only) 3 times higher, highlighting the significant role of acid sites in the metal-catalyzed hydrodeoxygenation reactions of phenolics. While Pt/HBeta and Pt/SiO2 exhibit similar rates of coke formation, the former has a higher stability than the latter under the same reaction conditions.

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“…As shown in Fig. 3, while only aromatics were seen in the reactor output at 450 o C, phenolics accounted for more than 20% of the total output at 600 o C. It is well known that isomerization and transalkylation of cresols readily occurs over acidic zeolites at moderate reaction temperature [24,[29][30][31]. However, due to the strong adsorption, all of these phenolic compounds remain trapped inside the zeolite until temperature is high enough to let them desorb.…”

Section: Product Evolution and Formation Of Carbonaceous Deposits As mentioning

confidence: 94%

Role of a phenolic pool in the conversion of m-cresol to aromatics over HY and HZSM-5 zeolites

Resasco

2014

Applied Catalysis A: General

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The conversion of m-cresol over two acidic zeolites has been studied on a micro-pulse reaction system in the temperature range of 400-600 o C. The zeolites were HZSM-5 and HY and had the same Si/Al ratio of 40. At 400 o C both zeolites were found to be highly efficient in trapping irreversibly the phenolic reactant. As the temperature increased, the extent of phenolic trapping was lower, resulting in a reduced amount of carbonaceous deposits, while the coke became more graphitic. While m-cresol only produced isomers and transalkylation vapor phenolic products, the vast majority of the amount of injected m-cresol resulted in condensed products on the surface that lead to the formation of a phenolic pool. Therefore, the aromatic hydrocarbons that dominate the reactor output originate from the cracking of the surface pool. At low reaction temperature, toluene is the major pool cracking product, but, at higher temperatures the selectivity to benzene increases. Independent measurements of toluene and xylene conversion, under the same conditions, indicate that these changes in selectivity are not due to secondary reactions of toluene to benzene, but rather a change in the cracking pattern of the surface pool.

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Comparison of Cresol Transformation on USHY and HZSM-5

Cited by 16 publications

References 22 publications

Shape selectivity vapor-phase conversion of lignin-derived 4-ethylphenol to phenol and ethylene over acidic aluminosilicates: Impact of acid properties and pore constraint

Shape selectivity vapor-phase conversion of lignin-derived 4-ethylphenol to phenol and ethylene over acidic aluminosilicates: Impact of acid properties and pore constraint

Efficient Conversion of m-Cresol to Aromatics on a Bifunctional Pt/HBeta Catalyst

Role of a phenolic pool in the conversion of m-cresol to aromatics over HY and HZSM-5 zeolites

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