A Robust Mesoporous Al₂O₃‐Based Nanocomposite Catalyst for Abundant NO_x Storage with Rational Design of Pt and Ba Species

Abstract

The nanostructural design of heterogeneous catalysts has often been demanded for assessing synergetic effects, which should be developed further by using high‐surface‐area porous metal oxide supports. However, such opportunities have been undermined by the poor stability of ordered mesoporous structures. Herein, rational design is demonstrated to obtain nanocomposite catalysts showing improved NOx storage properties owing to the presence of Ba species over a well‐designed mesoporous alumina (Al2O3) support. It is found that Ba species are impregnated successfully only after the stabilization of the mesoporous structure by full crystallization of Al2O3 frameworks to the γ‐phase, with the formation of Pt nanoparticles coinciding with complete removal of organic components. All the insights during this synthetic procedure are essential for designing high‐performance catalysts to purify and recover NOx molecules, and are applied for designing a variety of cutting‐edge mesoporous nanocomposite catalysts.

Catalytic conversion to ammonia through solid-state nitrate as a proposal for the emerging usage of nitrogen oxides

“…2e). 14,15 The presence of BaCO 3 species was also confirmed as a result of the unavoidable reaction of the Ba species with carbon dioxide (CO 2 ) in air after the preparation of the catalyst. The N 2 adsorption–desorption isotherm was type IV (Fig.…”

“…To synthesize NH 3 from NO via NO 2 and NO 3 − , a broad range of nanocomposite catalysts was prepared by using the surfactant-assisted method to obtain mesoporous alumina (mAl 2 O 3 ) powder samples with one-pot doping of platinum group metal (PGM) and subsequent impregnation of AEM species, 14,15 named AEM/PGM@mAl 2 O 3 . PGM and AEM were utilized as oxidation/reduction metal catalyst and NOx storage component, which could work sufficiently at a constant temperature ( e.g.…”

“…3a). 14,15 By switching the inlet gas to a reduction gas (1% H 2 ), stored NOx was actually converted to gaseous NH 3 (0.23 mmol g cat −1 ) without the detection of other nitrogen species such as NO, NO 2 or N 2 O (Fig. 2h).…”

“…According to our previous work, 14,15 PGM nanoparticle (NP)doped mesoporous alumina catalysts were prepared in one-pot by spray-drying. Typically, Al(Osec-Bu) 3 (24.6 g) was added to EtOH (60 mL), hydrolyzed for 3 h under stirring with the dropwise addition of 35.5% HCl (14.5 mL in total), and combined with an ethanolic solution (120 mL) of Pluronic P123 (15.0 g) and PGM source (PGM/Al 2 O 3 = 1/100 as the weight ratio).…”

Enhanced γ-phase crystallinity of Al2O3 frameworks at the concave surface of PS-b-PEO templated spherical pores

“…Our recently developed porous Al 2 O 3 particles (BET surface area; ∼400 cm 2 g −1 after calcination at 400°C) are also not stable during impregnation of functional species such as metal species inside the mesopores even after crystallization to its γ-phase. 53 Accordingly, the current insight into a stable interior porous structure showing a high specific surface area is a rational guideline for the preparation of a wide variety of highly porous platforms, which contributes to the next challenge to stimulate a variety of research fields such as porous materials design including facile preparation of nanocomposite catalysts, device manufacturing by utilizing highly active surfaces for electrodes and energy storage media, and so on.…”