Infrared Study of Pyridine Adsorbed on Unpromoted and Promoted Sulfated Zirconia

A solid-state NMR, FT-IR and TPD study on acid properties of sulfated and metal-promoted zirconia: Influence of promoter and sulfation treatment

“…For example, by means of the combined IR, frequency response (FR) and TPD techniques using NH 3 as the probe molecule, Barthos et al [19] revealed that SZ contains two types of Lsites of distinctly different acid strengths as well as B-sites with broad distribution of acid strengths. Davis et al [33] performed a series of studies on Pt/SZ and SZ catalysts by pyridine-IR, and reported a B/L ratio of ca. 0.8-1.0 for a SZ sample prepared by using 1N H 2 SO 4 (similar to the SZ-1.0N sample reported herein).…”

“…Nonetheless, while some of the above methods are useful in providing qualitative information (e.g., acid types) of the acid sites, most techniques are capable of providing only quantitative (acid amount and/or strength) information regarding to the overall acidity of solid acid catalysts. In this context, numerous reports on acidity characterization of SZ and assorted M/SZ catalysts can be found using the aforementioned conventional techniques [17][18][19][20][21][22][23][24][25][26][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. A novel solid-state 31 P magic-angle-spinning (MAS) NMR technique developed recently using trialkylphosphine oxides as probe molecules, however, reveals the propensity in providing detailed acid features, namely the types (Brønsted versus Lewis acidity), concentrations (distributions and amounts) and strength of acid sites in solid acid catalysts simultaneously [27,[43][44][45].…”

Iron oxide supported sulfated TiO2 nanotube catalysts for NO reduction with propane

“…As shown in the figure, all the spectra showed additional peaks at 1447, 1489 and 1540 cm À 1 . These peaks were appeared due to the chemisorption of pyridine molecules on different type of surface acidic sites [42]. The peak at 1447 cm À 1 was due to the interaction of pyridine with Lewis acidic sites (exposed metal cations), while the peak at 1540 cm À 1 was due to the protonation of pyridine molecule by the Brönsted acid sites (surface-bound sulfate groups) [43].…”

An Integrated Catalytic and Transient Study of Sulfated Zirconias: Investigation of the Reaction Mechanism and the Role of Acidic Sites in n‐Butane Isomerization

“…[8,9] Previous studies in this field have employed a variety of characterization techniques and catalytic testing to describe the composition and the nature of the acidity, and their influence on the reaction mechanism, using different SZ model systems. [10][11][12][13][14][15][16][17] Changes in the surface structure of SZs were studied by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), whereas adsorption of pyridine was used to determine Brønsted/Lewis ratios. [8,12,18] In situ investigations with nbutane under standard reaction conditions were performed using UV/Vis spectroscopy to study the formation of unsaturated compounds, [19] and temperature-programmed desorption (TPD) of ammonia was recently used to determine the number and distribution of acidic sites on SZ by a combination of IR spectroscopy, mass spectrometry, and a theoretical approach, whereby the cracking of n-heptane was correlated to strong Brønsted sites.…”