La1–xKxCoO3 and LaCo1–yFeyO3 Perovskite Oxides: Preparation, Characterization, and Catalytic Performance in the Simultaneous Removal of NOx and Diesel Soot

An Overview on the Catalytic Materials Proposed for the Simultaneous Removal of NOx and Soot

Vehicular pollution has become a major problem in urban areas due to the exponential increase in the number of automobiles. Typical exhaust emissions, which include nitrogen oxides (NOx), hydrocarbons (HC), carbon monoxide (CO), soot, and particulate matter (PM), doubtless have important negative effects on the environment and human health, including cardiovascular effects such as cardiac arrhythmias and heart attacks, and respiratory effects such as asthma attacks and bronchitis. The mitigation measures comprise either the use of clean alternative fuels or the use of innovative technologies. Several existing emission control technologies have proven effective at controlling emissions individually, such as selective catalytic reduction (SCR) and lean NOx trap (LNT) to reduce NOx and diesel particulate filter (DPF) specifically for PM abatement. These after-treatment devices are the most profitable means to reduce exhaust emissions to acceptable limits (EURO VI norms) with very little or no impact on the engine performances. Additionally, the relative lack of physical space in which to install emissions-control equipment is a key challenge for cars, especially those of small size. For this reason, to reduce both volume and cost of the after-treatment devices integrated catalytic systems (e.g., a sort of a "single brick") have been proposed, reducing both NOx and PM simultaneously. This review will summarize the currently reported materials for the simultaneous removal of NOx and soot, with particular attention to their nature, properties, and performances.

Effect of A-site substitution on the simultaneous catalytic removal of NOx and soot by LaMnO3 perovskites

The simultaneous catalytic removal of NO_x and soot by La_1−xM_xMnO₃ (M = K, Sr, Pr; x = 0, 0.1, 0.2, 0.3) perovskites was investigated.

Perovskite-based catalysts for the control of nitrogen oxide emissions from diesel engines

Nitrogen oxides removal over a wide range of perovskite-based catalysts together with their property-activity relationships.

Constructing a three-dimensionally ordered macroporous LaCrOδ composite oxide via cerium substitution for enhanced soot abatement

The addition of Ce into Cr-based perovskite restrained the growth of the crystal size and delayed the transformation from LaCrO₄ to LaCrO₃, and thus, the 3DOM structure was maintained even after calcination at 800 °C.

KNO3 supported on three-dimensionally ordered macroporous La0.8Ce0.2Mn1−xFexO3 for soot removal

The KNO₃ supported on 3DOM La_0.8Ce_0.2Mn_1−xFe_xO₃ perovskites have been prepared and used for soot removal. The presence of potassium nitrate can accelerate the soot combustion at both low and high temperature. The catalysts exhibit high activities for soot combustion.

Facile synthesis of three-dimensionally ordered macroporous silicon-doped La0.8K0.2CoO3 perovskite catalysts for soot combustion

Three-dimensionally ordered macroporous (3DOM) silicon-doped La_0.8K_0.2CoO₃ perovskite catalysts were successfully prepared by a colloidal crystal templating method. The catalysts showed a well-ordered macroporous structure and exhibited high activity for soot removal.

Catalytic combustion of soot over Ce and Co substituted three-dimensionally ordered macroporous La1−xCexFe1−yCoyO3 perovskite catalysts

Three-dimensionally ordered macroporous (3DOM) La_1−xCe_xFe_1−yCo_yO₃ (x = 0–0.4, y = 0–0.6) perovskite catalysts were successfully prepared by colloidal crystal templating method and employed for soot combustion.