Acid-Base and Catalytic Properties of Alkali Metal Exchanged ZSM5

Derewinski, Miroslaw A.; Haber, J.; Ptaszyński, J.; Lercher, Johannes A.; Rumplmayr, Gerd

doi:10.1016/s0167-2991(09)60970-8

Cited by 22 publications

(10 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Comparing the present NH 3 -and CO 2 -TPD results for Cs x Na 1-x β and Rb x Na 1-x β with those for K x Na 1-x β of similar x in our previous work [30] would show that the acidity of alkali-ion exchanged β zeolite (M x Na 1-x β, M = K + , Rb + and Cs + ) decreased but the basicity increased with the radius of the alkali ion, in line with many earlier reports in literature [18][19][20]38,39].…”

Section: Composition and Physicochemical Propertiessupporting

confidence: 90%

Sustainable production of acrylic acid: Rb+- and Cs+-exchanged Beta zeolite catalysts for catalytic gas-phase dehydration of lactic acid

Yan

Mahmood

et al. 2016

Catalysis Today

View full text Add to dashboard Cite

Rb + -and Cs + -exchanged Beta zeolites (Rb x Na 1-x β and Cs x Na 1-x β) of varying exchange degrees (x = 0~1.00) were employed to catalyze the gas-phase dehydration of lactic acid (LA) for sustainable production of acrylic acid (AA) in a flow fixed-bed reactor at 360 o C, using an aqueous solution of LA (10 mol% or 35.7%) as the reaction feed at a weight hourly space velocity by LA of 2.1 h -1 . An appropriate window of the ion exchange degrees for highly selective AA production (≥ 60 mol%) was determined for either series of the samples, i.e., x = 0.85~0.98 for the Rb x Na 1-x β and x = 0.71~0.90 for the Cs x Na 1-x β samples. The best performing catalysts Rb 0.95 Na 0.05 β, and Cs 0.81-0.90 Na 0.19-0.10 β offered the highest AA selectivity (ca. 70 mol%) and yield (ca. 60~65 mol%) for reaction periods of longer than 10 h. Measurements of the surface acidity and basicity of the catalyst samples bytemperature-programmed desorption of NH 3 and CO 2 showed that the highly selective catalysts in such widows should have both weakly acidic and weakly basic surface sites with suitably balanced acidity and basicity. The acid-catalyzed decarbonylation/decarboxylation and base-catalyzed condensation of LA, which lead respectively to formation of acetaldehyde and 2,3-pentanedione, always occurred as the competing reactions over the investigated catalysts. Observations on the catalyst selectivity changes for these competing reactions clearly demonstrate that the suitably balanced acidity and basicity at the catalyst surface is the key to the high selectivity for the desired dehydration reaction.

show abstract

Section: Composition and Physicochemical Propertiessupporting

confidence: 90%

Sustainable production of acrylic acid: Rb+- and Cs+-exchanged Beta zeolite catalysts for catalytic gas-phase dehydration of lactic acid

Yan

Mahmood

et al. 2016

Catalysis Today

View full text Add to dashboard Cite

show abstract

“…Besides the zeolite type, the number y was also known as an important affecting factor to the acid–base property of zeolite catalysts. − Figures and show the effect of y on the NH 3 - and CO 2 -TPD profiles normalized to a unit surface area for the K 0.90+ m Na 0.10‑ m β_ y (22 ≤ y ≤ 111) and K 0.90+ m Na 0.10‑ m ZSM-5_ y (27 ≤ y ≤ 75) samples with very similar nominal K + -exchange degree ( m ≤ 0.08), respectively. The peak temperature (strength) and surface acidity (amount or peak intensity) registered from the NH 3 -TPD profiles for K 0.90+ m Na 0.10‑ m β_ y increased from 186 °C and 46 × 10 –3 μmol NH 3 ·m –2 to 233 °C and 608 × 10 –3 μmol NH 3 ·m –2 , respectively, when the number y was lowered from 111 to 22 (Figure A).…”

Section: Resultsmentioning

confidence: 99%

Potassium-Ion-Exchanged Zeolites for Sustainable Production of Acrylic Acid by Gas-Phase Dehydration of Lactic Acid

et al. 2016

View full text Add to dashboard Cite

Development of high-performance solid acid catalysts for chemicals and materials production from bioresourced feedstock has become an important research topic in heterogeneous catalysis for renewable energy and green chemistry. We provide herein a comprehensive study on the catalytic performance of various K +exchanged zeolites (K x Na 1-x Z_y, x = 0.90−0.98) with similar molar K/Al ratios for acrylic acid (AA) production by gas-phase dehydration of lactic acid (LA) and discuss the effects of zeolite type (Z = ZSM-22, ZSM-35, MCM-22, ZSM-11, ZSM-5, ZSM-5/ ZSM-11, and β) and SiO 2 /Al 2 O 3 ratio (y). ZSM-5 and β are found more efficient than the other zeolites for this LA-to-AA reaction. Variation of y in the zeolite (β and ZSM-5) is shown to significantly affect the catalytic performance: not only higher AA selectivity and yield but also better catalytic stability is achieved by lowering y. A K 0.97 Na 0.03 ZSM-5_27 is then identified as the best-performing catalyst, offering very high AA selectivity (80−81 mol%) and yield (74−78 mol%) at 360 °C under high LA space velocity (WHSV LA = 2.1 h −1 ). This catalyst also shows a remarkable long-term stability, being capable to maintain a high AA selectivity (>70 mol%) and yield (>55 mol%) for longer than 80 h. Furthermore, an in situ calcination of the used catalyst with flowing air at 450 °C is shown to be efficient for complete catalyst regeneration. Correlating the catalyst performance with its surface acid− base property measured by NH 3 -and CO 2 -TPD clearly uncovers that balance between the surface acidity and basicity would be a key, besides Z and y of the zeolite, to the catalyst performance.

show abstract

“…In general, the interaction of benzene with Lewis acid sites is stronger than with Br~nsted acid sites [129]. This stems from the fact that in contrast to the asymmetric bonding of the proton to the aromatic ring, the larger metal cations can interact symmetrically with all delocalized electrons in the aromatic ring which enhances the strength of the interaction.…”

Section: Benzene and Substituted Benzenesmentioning

confidence: 99%

“…Benzene is problematic to use for probing the strength of Lewis acids, because the interaction with the benzene ring will encompass the electron pair acceptor strength of the cation and the geometric match between the ring 7r-electron system and the cation. A good example for this is the increasing strength of interaction of benzene with increasing size of the alkali cation in ZSM5 [166], although the Lewis acid strength of the cation decreases with its size when probed with other basic molecules as CO [14] or light alcohols [167]. For a given oxide, the strength of the Lewis acid site depends upon the coordination and formal charge of the cation.…”

Section: Lewis Acid Sitesmentioning

confidence: 99%

Infrared studies of the surface acidity of oxides and zeolites using adsorbed probe molecules

1996

View full text Add to dashboard Cite

show abstract

Acid-Base and Catalytic Properties of Alkali Metal Exchanged ZSM5

Cited by 22 publications

References 16 publications

Sustainable production of acrylic acid: Rb+- and Cs+-exchanged Beta zeolite catalysts for catalytic gas-phase dehydration of lactic acid

Sustainable production of acrylic acid: Rb+- and Cs+-exchanged Beta zeolite catalysts for catalytic gas-phase dehydration of lactic acid

Potassium-Ion-Exchanged Zeolites for Sustainable Production of Acrylic Acid by Gas-Phase Dehydration of Lactic Acid

Infrared studies of the surface acidity of oxides and zeolites using adsorbed probe molecules

Contact Info

Product

Resources

About