Bioethanol conversion into hydrocarbons on HZSM-5 and HMCM-22 zeolites: Use of in situ DRIFTS to elucidate the role of the acidity and of the pore structure over the coke formation and product distribution

Sousa, Zilacleide S.B.; César, Deborah Vargas; Henriques, Cristiane A.; Silva, Victor Teixeira da

doi:10.1016/j.cattod.2014.03.023

Cited by 42 publications

(58 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This is accompanied by a change in the 3000 to 2880 cm -1 region where the intensity of the peaks at 2903 and 2875 cm -1 decrease as the signal at 2938 cm -1 increases. [24,29] As these signals are still present above 200 o C, they are attributed to the chemisorbed ethoxy species. This is likely due to a decrease in all four of the ethanol peaks (2982, 2938, 2903 and 2875 cm -1 ), and an increase in the ethoxy signal (2938 and 2982 cm 1 ).…”

Section: Resultsmentioning

confidence: 99%

“…[29] This last observation suggests that is commonly attributed to methyl rocking of C-C-O-C-C species, which suggests the early (low temperature) formation of diethyl ether species. [24,25,30] It is noted that other bands may also be attributed to diethyl ether, though these bands (2982, 2875, 1485, 1450 and 1395 cm -1 ) typically overlap with ethanol and the ethoxy species. [24,25,30] The appearance of diethyl ether at low temperature is partly attributed to the strong acid sites present on SAPO-34, and also due to the energetic incentive of forming diethyl ether (-42 kJ/mol).…”

Section: Resultsmentioning

confidence: 99%

“…[24,25,30] It is noted that other bands may also be attributed to diethyl ether, though these bands (2982, 2875, 1485, 1450 and 1395 cm -1 ) typically overlap with ethanol and the ethoxy species. [24,25,30] The appearance of diethyl ether at low temperature is partly attributed to the strong acid sites present on SAPO-34, and also due to the energetic incentive of forming diethyl ether (-42 kJ/mol). The feature at 1145 cm -1 diminishes, disappearing above 200 o C, coinciding with the appearance of ethylene in the gas-phase mass spectrometry analysis ( Figure S3).…”

Section: Resultsmentioning

confidence: 99%

“…Further evidence supporting this theory can be seen in the 1230 region and the 1030 cm -1 band, which rapidly decrease as temperature increases, showing that physisorbed ethanol was also contributing to these bands. [24,28] Given that the surface ethoxy species and weakly bound ethanol have very similar bands, the exact contributions of the two cannot be distinguished in the C-H or C-C region. However as the temperature increases it is clear the chemisorbed surface ethoxy species become more prevalent in the spectra.…”

Section: Resultsmentioning

confidence: 99%

“…As further evidence that ethanol has displaced water, a range of C-H stretching signals are now present between 3000 and 2870 cm -1 . [23][24][25][26][27] The first two features (2982 and 2938 cm -1 ) are ascribed to asymmetric stretches of the CH 3 and CH 2 species respectively, whereas the latter two signals (2903 and 2875 cm -1 ) are the corresponding symmetric stretches. [24] These species are diagnostic of ethanol interactions with Brønsted acid sites, and have been observed for a range of solid-acid materials, confirming the interactions between ethanol and the SAPO-34 catalyst.…”

Section: Resultsmentioning

confidence: 99%

See 4 more Smart Citations

Spectroscopic investigation into the design of solid–acid catalysts for the low temperature dehydration of ethanol

Potter

Aswegen

Gibson

et al. 2016

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

The increased demand for bulk hydrocarbons necessitates research into increasingly sustainable, energy-efficient catalytic processes. Owing to intricately designed structure-property correlations, SAPO-34 has become established as a promising material for the low temperature ethanol dehydration to produce ethylene. However, further optimization of this process requires a precise knowledge of the reaction mechanism at a molecular level. In order to achieve this a range of spectroscopic characterization techniques are required to probe both the interaction with the active site, and also the wider role of the framework. To this end we employ a combination of in situ infra-red and neutron scattering techniques to elucidate the influence of the surface ethoxy species in the activation of both diethyl ether and ethanol, towards the improved formation of ethylene at low temperatures. The combined conclusions of these studies is that the formation of ethylene is the rate determining step, which is of fundamental importance towards the development of this process and the introduction of bio-ethanol as a viable feedstock for ethylene production.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 3 more Smart Citations

Spectroscopic investigation into the design of solid–acid catalysts for the low temperature dehydration of ethanol

Potter

Aswegen

Gibson

et al. 2016

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

show abstract

Ethanol to Aromatics on Modified H‐ZSM‐5 Part II: An Unexpected Low Coking

Seifert

Marschall

Gille

et al. 2020

Chemistry An Asian Journal

View full text Add to dashboard Cite

In this study a commercial H-ZSM-5 zeolite (Si/Al = 11) was post-synthetically modified by a combined dealumination procedure to adjust its catalytic properties for the selective formation of aromatics from ethanol. The solid-state properties of original and modified zeolites are determined by structural, textural and acidity analysis. The formation of aromatics and durability of the zeolites were investigated depending on space velocity or contact time in the catalyst bed. In particular, the formation rate and desorption of aromatics from solid-state surface as well as their tendency to form coke precursors by consecutive build-up reactions determine the formation of coke. Therefore, the rate of buildup and finished aromatization by hydride transfer (predetermined by the kind, location and geometric arrangement of surface acid sites) and the statistical number of reaction events until final desorption at the specific contact time have to be harmonized to increase aromatics yield and to decrease catalyst decay by coke simultaneously.

show abstract

Catalytic Dehydration of 1,4‐Butanediol over Mg−Yb Binary Oxides and the Mechanism Study

et al. 2020

ChemCatChem

View full text Add to dashboard Cite

In this study, MgÀ Yb binary oxides were synthesized using different MgO concentrations and investigated for the catalytic dehydration of 1,4-butanediol (BDO) into 3-buten-1-ol (BTO). The physicochemical properties of the catalysts were characterized by N 2 physisorption, X-ray diffraction, Raman spectroscopy, temperature-programmed techniques, and diffuse reflectance infrared Fourier transform spectroscopy. The MgÀ Yb binary oxides exhibited superior catalytic activity and better BTO selectivity compared with the pristine Yb 2 O 3 or MgO. Structures of MgÀ OÀ Yb were generated in the binary oxides via the interchange of Yb or Mg in the MgO or Yb 2 O 3 crystalline phases. Extra basic and acidic sites were formed over the MgÀ Yb binary oxides because of the formation of surface defects and the presence of MgÀ OÀ Yb structures, respectively. The acidic as well as basic sites were observed to influence the catalytic performance: BDO reactivity was enhanced by the more acidic sites, while BTO selectivity was favored by the basic sites. The highest BTO yield of 71.1 % was achieved over the Mg7Yb3 catalyst with 90.4 % BDO conversion and 78.6 % BTO selectivity at 350°C. The in situ DRIFTS results indicated that BDO was first adsorbed on the catalyst and then reacted with the acidic sites to generate butoxides. The β-H of the surface butoxides was abstracted by the basic oxygen anions to produce aldehyde species, which dissociated to form BTO.[a] R.

show abstract

Bioethanol conversion into hydrocarbons on HZSM-5 and HMCM-22 zeolites: Use of in situ DRIFTS to elucidate the role of the acidity and of the pore structure over the coke formation and product distribution

Cited by 42 publications

References 54 publications

Spectroscopic investigation into the design of solid–acid catalysts for the low temperature dehydration of ethanol

Spectroscopic investigation into the design of solid–acid catalysts for the low temperature dehydration of ethanol

Ethanol to Aromatics on Modified H‐ZSM‐5 Part II: An Unexpected Low Coking

Catalytic Dehydration of 1,4‐Butanediol over Mg−Yb Binary Oxides and the Mechanism Study

Contact Info

Product

Resources

About