Direct Molten Polymerization Synthesis of Highly Active Samarium Manganese Perovskites with Different Morphologies for VOC Removal

Abstract

A morphology-controlled molten polymerization route was developed to synthesize SmMnO (SMO) perovskite catalysts with netlike (SMO-N), granular-like (SMO-G), and bulk (SMO-B) structures. The SMO perovskites were formed directly by a molten polymerization method, and their morphologies were controlled by using the derivative polymers as templates. Among all catalysts, the porous SMO-N exhibited the highest activity, over which the toluene, benzene, and o-xylene were completely oxidized to CO at 240, 270, and 300 °C, respectively, which was comparable to that of typical noble-metal catalysts. The apparent activation energies of toluene over SMO-N (56.4 kJ·mol) was much lower than that of SMO-G (70.8 kJ·mol) and SMO-B (90.1 kJ·mol). Based on the results of scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and H temperature-programmed reduction characterization, we deduce that the excellent removal efficiency of volatile organic compounds (VOCs) over SMO-N catalyst was attributable to the special structure, high surface Mn/Mn and O/O molar ratios, and strong reducibility. Due to the high activity, low cost, and simple preparation strategy, the SMO catalyst is a promising catalyst for VOC removal.

The Influence of the Chemical Potential on Defects and Function of Perovskites in Catalysis

“…The dominant oxidation state of manganese in perovskites is Mn 3+ , accompanied by smaller proportions of Mn 2+ and Mn 4+ (Figure 4). (Levasseur and Kaliaguine, 2008;Liu et al, 2018b;Liu et al, 2019) Mn 2+ species were already present in the fresh Sm 0.96 MnO 3 catalyst (Koch et al, 2020) balanced by about 5% Mn 4+ resulting in an average oxidation state of 3.03. After heating in 20% O 2 , the average oxidation state decreased to 3.00.…”

“…Defect-rich structures are of particular importance with respect to the application of perovskites in heterogeneous catalysis (Royer et al, 2014;Najjar and Batis, 2016). In addition to the increasing interest in perovskites as catalysts for oxygen reduction and oxygen evolution reactions (Suntivich et al, 2011;Gupta et al, 2016;Zhu et al, 2019), this class of materials is also widely used in photocatalysis (Grabowska, 2016;Tasleem and Tahir, 2020) or total oxidation to remove volatile organic and hazardous compounds (Gil et al, 2004;Liu et al, 2018a;Liu et al, 2018b;Liu et al, 2019). However, perovskites are also suitable catalysts for selective oxidations at low temperatures (Polo-Garzon and Wu, 2018;Kamata, 2019), especially for the oxidative dehydrogenation of propane (Koch et al, 2020).…”

Pt/MnO2 Nanoflowers Anchored to Boron Nitride Aerogels for Highly Efficient Enrichment and Catalytic Oxidation of Formaldehyde at Room Temperature

“…However, the maximum capacity of the adsorbent and hazards associated with desorption during the regeneration process hinders the effectiveness of adsorbents. Conversely, catalytic oxidation can continuously and completely covert gaseous HCHO into harmless CO 2 and H 2 O [4e–f] …”

A Brief Review on Key Role of Perovskite Oxides as Catalyst

“…[1] Perovskite oxides are widely studied due to their stability and accessibility coupled with interesting properties.They contain many manufacturing applications in ceramic objects, electronics, nuclear research, and mainly in catalysis. [2][3][4][5][6] In the ideal cubic (ABO 3 ) perovskite oxide, the A cation is located at the body-centered position, and the BO 6 octahedra placed in a corner shared arrangement with each other. The formation and stability of the perovskites depend on the size and charge of the cations (A and B) and are exemplified appropriately by Goldschmidt as a tolerance factor T f .…”