Manufacture of dimethyltetralins

Sikkenga, David L.; Lamb, James; Zaenger, I.C.

doi:10.1016/s0144-2449(05)80247-7

Cited by 10 publications

(9 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Catalyst activity is low due to equilibrium limitations and build-up of product H 2 ; rapid loss of activity occurs due to coke formation (1) Temperatures gradients were measured during burn off of coke formed on a chromia-alumina catalyst during butene dehydrogenation; data were used in developing a mathematical model for predicting temperatures and coke profiles (2) Coked supported palladium catalyst used in the dehydrogenation of dimethyltertrahydronaphthalenes to dimethylnaphthalenes is reactivated with an organic polar solvent at a temperature below 200 °C [270,271] Loss of activity due to poisoning of acid sites and blocking of small zeolite pores by coke (1) Regeneration of noble metal/zeolite via progressive partial removal of carbonaceous deposits under controlled oxidizing conditions to maximize sorption of a probe molecule while minimizing metal sintering (2) Regeneration of noble metal/zeolite in air at about 600 °C, followed by a mild treatment in aqueous ammonia to improve catalytic activity [277,278] Severe coking and deactivation of silica-alumina and Y-zeolite catalysts observed during high conversions of MeOH; also substantial coking of ZSM-5, other zeolites, and aluminophosphate molecular sieves (1) Kinetics of coke burnoff from a SAPO-34 used in converting methanol to olefins were studied; kinetics are strongly dependent on the nature of the coke. Kinetics are slowed by strong binding of coke to acid sites (2) ZSM-34 catalyst used in conversion of methanol to light olefins is effectively regenerated in H 2 -containing gas; this approach avoids the formation of catalyst-damaging products such as steam that would be formed during burn off in air [281,282] …”

Section: Regeneration Of Deactivated Catalystsmentioning

confidence: 99%

Heterogeneous Catalyst Deactivation and Regeneration: A Review

2015

View full text Add to dashboard Cite

Deactivation of heterogeneous catalysts is a ubiquitous problem that causes loss of catalytic rate with time. This review on deactivation and regeneration of heterogeneous catalysts classifies deactivation by type (chemical, thermal, and mechanical) and by mechanism (poisoning, fouling, thermal degradation, vapor formation, vapor-solid and solid-solid reactions, and attrition/crushing). The key features and considerations for each of these deactivation types is reviewed in detail with reference to the latest literature reports in these areas. Two case studies on the deactivation mechanisms of catalysts used for cobalt Fischer-Tropsch and selective catalytic reduction are considered to provide additional depth in the topics of sintering, coking, poisoning, and fouling. Regeneration considerations and options are also briefly discussed for each deactivation mechanism.

show abstract

Section: Regeneration Of Deactivated Catalystsmentioning

confidence: 99%

Heterogeneous Catalyst Deactivation and Regeneration: A Review

2015

View full text Add to dashboard Cite

show abstract

“…4 Therefore, the synthesis of 2,6-DMN from the ten DMN isomers has been studied. [4][5][6][7] The alternative process of 2,6-DMN production, the methylation of methylnaphthalene (MN), has also been investigated [8][9][10][11][12] intensively.…”

Section: Introductionmentioning

confidence: 99%

Structures and Energetics of the Methylation of 2-Methylnaphthalene with Methanol over H-BEA Zeolite

2010

View full text Add to dashboard Cite

The methylation of 2-methylnaphthalene (2-MN) with methanol to the 2,6 (2,6-DMN) and 2,7 (2,7-DMN) dimethylnaphthalenes catalyzed over nanoporous BEA zeolite has been investigated quantum chemically using the M06-2X density functional. The catalytic cycle consists of three elementary steps: (1) formation of a methoxy species from methanol that is bound to a zeolite oxygen atom, (2) methylation of 2-MN to DMN with methoxy leading to naphthalynic carbocations, and (3) formation of DMN by proton back-donation from naphthalynic carbocations. The reaction profiles are similar for both the 2,6 and the 2,7 isomer and are in agreement with the experimental observation that they are produced in equal amounts on acidic BEA zeolite. A possible side reaction, the formation of dimethyl ether via the self-activation of methanol, is also discussed. The stability of the intermediates inside the pores is, to a large extent, governed by the steric constraints and the van der Waals dispersion interactions induced by the pore structure of BEA zeolite. These are the key parameters for understanding the relationship between zeolite topology and catalytic activity.

show abstract

“…Carbon deposits during liquid-phase dimethyltetrahydronaphthalene dehydrogenation to dimethylnaphthalene on Pd/carbon were reported to be removed by polar organic solvents such as methanol and acetone in a temperature range from 20 to 150 °C. 212 Carbon deposits during aqueous-phase 2-pentanone hydrogenation were found to be soluble in DMSO. 195 This solvent washing can be applied for periodic in situ regeneration.…”

Section: Design Strategies To Improve Hydrothermal Stability Of Suppo...mentioning

confidence: 99%

Improving Hydrothermal Stability of Supported Metal Catalysts for Biomass Conversions: A Review

2021

View full text Add to dashboard Cite

Catalyst stability is one of the greatest challenges faced for the utilization of heterogeneous catalysts in the development of biomass conversion to chemicals and fuels. As many biomass transformations are performed in water, hydrothermal stability of supported metal catalysts is especially critical. This Review aims to increase attention on the hydrothermal stability of supported metal catalysts by looking at the stability of common catalyst supports, deactivation modes, and strategies to improve their durability. While common oxides such as silica, alumina, zeolite, and zirconia are not stable to hydrolytic attack, carbon, and titania show promising resistance. In addition to catalyst support leaching, amorphization, and collapse caused by hydrothermal conditions, supported metal catalysts can deactivate by sintering, leaching, poisoning, carbon deposition, and restructuring of the active metal sites. Several strategies are discussed to improve stability of supported metal catalysts: coating on the oxide, overcoating on the supported metal catalyst, metal−support interaction, embedding metal particles, bimetallic catalysts, reactor design and process optimization, and other methods. A fundamental understanding of liquid−solid interactions and deactivation mechanisms, as well as strategies to improve the catalyst durability will help to develop robust catalytic materials for the scale-up and further application of aqueous-phase biomass conversion processes.

show abstract

Manufacture of dimethyltetralins

Cited by 10 publications

References 0 publications

Heterogeneous Catalyst Deactivation and Regeneration: A Review

Heterogeneous Catalyst Deactivation and Regeneration: A Review

Structures and Energetics of the Methylation of 2-Methylnaphthalene with Methanol over H-BEA Zeolite

Improving Hydrothermal Stability of Supported Metal Catalysts for Biomass Conversions: A Review

Contact Info

Product

Resources

About