Catalytic activities and properties of mesoporous sulfated Al2O3–ZrO2

Abstract

Mesoporous sulfated Al 2 O 3 -ZrO 2 (MSAZ) catalysts with large surface areas and pore volumes after calcination at high temperature (650°C) and with higher Al 2 O 3 content than 20wt% were successfully prepared from a template of block copolymer (P84). The MSAZ catalysts were characterized by X-ray diffraction (XRD), N 2 adsorption, transmission electron microscopy (TEM), 27 Al magic-angle spinning nuclear magnetic resonance (MAS NMR), thermogravimetric analysis (TG-DTG), temperature-programmed desorption of ammonia (NH 3 -TPD) and infrared spectra (IR) of adsorbed pyridine. It is shown that the resulting mesostructured sulfated Al 2 O 3 -ZrO 2 samples have a well-developed textural mesoporosity. The number of acid sites present on MSAZ catalysts is higher than that on conventional sulfated zirconia, and the former catalysts are more active than the latter one for various acid-catalyzed reactions.

Enhanced Photocatalytic Activity of Hierarchical Macro-Mesoporous Anatase byZrO2Incorporation

“…The mean pore diameter of the T10Z-500 sample is effectively the lowest one, obtained by the BJH method from the corresponding adsorption and desorption data. The obtained specific surface areas are in agreement with those reported by other authors [49,50].…”

Self-Protected CeO2–SnO2@SO42–/TiO2 Catalysts with Extraordinary Resistance to Alkali and Heavy Metals for NOx Reduction

“…Upon comparing the TPD profiles of CeSn/Ti with those of K/CeSn/Ti, Pb/ CeSn/Ti, and K/Pb/CeSn/Ti catalysts, it could be found that K greatly decreased the amount of weak acid (below 200 °C) and Pb impaired the middle acid (200−400 °C) and strong acid (above 400 °C). 22,23 However, the reduction of acid sites in CeSn/Ti-SA catalysts varied from that in CeSn/Ti catalysts, the main loss in acidity of the poisoned catalysts (K/CeSn/Ti-SA, Pb/CeSn/Ti-SA, and K/Pb/CeSn/Ti-SA) was the superacid sites from SO 4 2− (above 600 °C), 24 other acid sites did not change much, indicating that K or/and Pb would preferentially impair the superacid sites instead of other acid sites. To further quantify the above conclusions, the amount of NH 3 desorption was calculated to illustrate the change in the acid amount of the catalyst before and after poisoning (Table S2), 25 the calculated results were in accord with the results observed in Figure 2A.…”

Utilization of Solid Acid SO42−/TiO2 as Catalyst to the Three‐Component Mannich Reaction at Ambient Temperature

“…These acids which are usually associated with two catalytic sites are able to activate a wide range of substrates because of the presence of both Brønsted and Lewis acidic sites . In this regard, Jing and co‐workers had made an interesting observation that solid acid SO 4 2 − /TiO 2 prepared at various calcination temperatures exhibited Lewis and Brønsted acidities to different extents, as confirmed from their in situ FIIR‐pyridine absorption frequencies at 1450 cm −1 and 1540 cm −1 respectively. It appears that ionic mode of mechanism is greatly assisted by the presence of a water source which can readily convert Lewis acidic sites into active Brønsted acids to activate the aldimines through ion‐pair formation in a typical Mannich reaction, as depicted in Figure .…”