Characterization of acylating intermediates formed on H-ZSM-5

Kresnawahjuesa, Oferi; Gorte, Raymond J.; White, D. R.

doi:10.1016/s1381-1169(03)00511-9

Cited by 45 publications

(49 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For temperatures below 550 K, this strong interaction will cause the acid sites to be essentially saturated with acetic acid and based on our previous study [32], the formation of the acetate intermediate from acetic acid will be slow at these temperatures. The experimental evidence that propene is excluded from the acid sites is that products that would normally be expected from the oligomerization of propene are not observed, even in a large excess of propene.…”

Section: Discussionmentioning

confidence: 78%

“…The experimental evidence that propene is excluded from the acid sites is that products that would normally be expected from the oligomerization of propene are not observed, even in a large excess of propene. With acetic acid, coking appears to occur through oligomerization of acetone that forms through an acetate intermediate [32]. Based on temperature-programmed-desorption (TPD) data, the acetate decomposes to CO 2 and a methyl group, which in turn is scavenged by a neighboring acetate group to form acetone.…”

Section: Discussionmentioning

confidence: 99%

“…Finally, we believe the present work demonstrates the importance of adsorption studies for understanding reaction chemistry. While we do not claim that the adsorption studies we carried out with propene [23][24][25] and acetic acid [32] allowed us to predict reaction properties, they certainly guided us in choosing the temperature range in which reaction occurred and in explaining the chemistry that was observed. The approach of performing TPD and spectroscopic measurements on reactant molecules provides a simple method of screening and is particularly useful for understanding how these materials can be used in fine-chemicals synthesis.…”

Section: Discussionmentioning

confidence: 99%

“…In parallel to the desired bimolecular reactions between acetic acid and propene are the undesirable side reactions. Acetic acid can react to form acetone and CO 2 [32][33][34][35][36][37]; olefins and ketones can undergo oligomerization and cracking to form a wide range of products [23,38]. of propene, balanced with He carrier gas to achieve a total flow rate of 50 ml/min.…”

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations

The acylation of propene by acetic acid over H-[Fe]ZSM-5 and H-[Al]ZSM-5

Kresnawahjuesa¹,

Gorte²,

White³

2004

Journal of Molecular Catalysis A: Chemical

Self Cite

View full text Add to dashboard Cite

We have studied the vapor-phase reaction of acetic acid with propene over H- [Al]ZSM-5 and H- [Fe]ZSM-5 molecular sieves between 425 and 600 K, for acetic acid partial pressures of 25 to 50 Torr, with propene:acetic acid ratios between 1 and 4. Reasonable conversions were obtained above 450 K. Both H-[Fe]ZSM-5 and H-[Al]ZSM-5 showed high activities at 450 K, with selectivities to propyl acetates of ~90% using a propene:acetic acid ratio of 2 and ketones formed by dehydration of the acetates making up most of the remaining products. The reaction rate was completely stable at 450 K for at least 20 h, and the product distribution was insensitive to the reactant feed ratio for a propene:acetic acid ratio above 2. On H-[Fe]ZSM-5, dehydration of the acetates became increasingly important at higher temperatures, with the selectivity to ketones approaching 80% at 525 K. At still higher temperatures, reaction pathways that did not involve propyl acetates became important. The high selectivity for forming propyl acetates and the absence of olefin oligomerization is believed to result from having the acid sites occupied (saturated) by acetic acid. Finally, the acid-site density measured on H-[Fe]ZSM-5 after weeks of catalyst testing remained the same as the initial site density, showing that this material has sufficient stability for fine-chemicals synthesis.

show abstract

Section: Discussionmentioning

confidence: 78%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

The acylation of propene by acetic acid over H-[Fe]ZSM-5 and H-[Al]ZSM-5

Kresnawahjuesa¹,

Gorte²,

White³

2004

Journal of Molecular Catalysis A: Chemical

Self Cite

View full text Add to dashboard Cite

show abstract

“…species to synthesize aromatic ketones via the Friedel-Crafts reaction [3][4][5][6][7]. However, to the best of our knowledge, the studies reported in the literature to detect such an acyl intermediate have been carried out adsorbing an acylating agent from the gas phase, while the real reactions take place in liquid phase.…”

Section: Introductionmentioning

confidence: 99%

ATR-FTIR Study of the Decomposition of Acetic Anhydride on Fosfotungstic Wells–Dawson Heteropoly Acid Using Concentration-Modulation Excitation Spectroscopy

et al. 2011

View full text Add to dashboard Cite

The decomposition of acetic anhydride in liquid phase on a fosfotungstic Wells-Dawson heteropoly acid (HPA) was investigated by in situ ATR-FTIR spectroscopy. Transient and concentration-modulation excitation spectroscopy (MES) experiments in combination with phase-sensitive detection (PSD) were used to monitor the solid-liquid interface. The MES method is based on the periodic variation of a parameter of the reaction media such as, the reactant concentration. That periodic alteration causes varying infrared signals of the surface adsorbed species that are subsequently demodulated with the PSD methodology. Thus, the separation of the static signals from the changing ones is achieved, and species with different response can be observed in the spectra. Using MES-PSD coupled with ATR-FTIR, acetic anhydride was observed to decompose to acetic acid, acetate and acyl [CH 3 C(O) ? ] species, involving Brønsted acid sites of the HPA catalyst. The CH 3 C(O) ? is a very unstable intermediate species and it is the key intermediate in the FriedelCrafts acylation reactions. Moreover, the acetate groups are spectator species since remain strongly adsorbed on the catalyst surface and do not further react.

show abstract

Thermal Methods

and

Auroux

2012

Characterization of Solid Materials and Heterogeneous Catalysts

View full text Add to dashboard Cite

Characterization of acylating intermediates formed on H-ZSM-5

Cited by 45 publications

References 36 publications

The acylation of propene by acetic acid over H-[Fe]ZSM-5 and H-[Al]ZSM-5

The acylation of propene by acetic acid over H-[Fe]ZSM-5 and H-[Al]ZSM-5

ATR-FTIR Study of the Decomposition of Acetic Anhydride on Fosfotungstic Wells–Dawson Heteropoly Acid Using Concentration-Modulation Excitation Spectroscopy

Thermal Methods

Contact Info

Product

Resources

About