Correction: Thermally stable mesoporous tetragonal zirconia through surfactant-controlled synthesis and Si-stabilization.

[This corrects the article DOI: 10.1039/D2RA01459A.].

Thermally stable mesoporous tetragonal zirconia through surfactant-controlled synthesis and Si-stabilization.

Thermally stable, highly mesoporous Si-stabilized ZrO2 was prepared by sol-gel-synthesis. By utilizing the surfactant dodecylamine (DDA), large mesopores with a pore width of ∼9.4 nm are formed. Combined with an NH3-treatment on the hydrogel, a high specific surface area of up to 225 m2 g-1 and pore volume up to 0.46 cm3 g-1 are obtained after calcination at 973 K. The individual contributions of Si-addition, DDA surfactant and the NH3-treatment on the resulting pore system were studied by inductively coupled plasma with optical emission spectrometry (ICP-OES), X-ray diffraction (XRD), N2 sorption, and transmission electron microscopy (TEM). Electron tomography was applied to visualize and investigate the mesopore network in 3D space. While Si prevents the growth of ZrO2 crystallites and stabilizes the t-ZrO2 phase, DDA generates a homogeneous mesopore network within the zirconia. The NH3-treatment unblocks inaccessible pores, thereby increasing specific surface area and pore volume while retaining the pore width distribution.

Hierarchically Structured Porous Spinels via an Epoxide-Mediated Sol-Gel Process Accompanied by Polymerization-Induced Phase Separation.

Enhancing the activity and stability of catalysts is a major challenge in scientific research nowadays. Previous studies showed that the generation of an additional pore system can influence the catalytic performance of porous catalysts regarding activity, selectivity, and stability. This study focuses on the epoxide-mediated sol-gel synthesis of mixed metal oxides, NiAl2O4 and CoAl2O4, with a spinel phase structure, a hierarchical pore structure, and Ni and Co contents of 3 to 33 mol % with respect to the total metal content. The sol-gel process is accompanied by a polymerization-induced phase separation to introduce an additional pore system. The obtained mixed metal oxides were characterized with regard to pore morphology, surface area, and formation of the spinel phase. The Brunauer-Emmett-Teller surface area ranges from 74 to 138 m2·g-1 and 25 to 94 m2·g-1 for Ni and Co, respectively. Diameters of the phase separation-based macropores were between 500 and 2000 nm, and the mesopore diameters were 10 nm for the Ni-based system and between 20 and 25 nm for the cobalt spinels. Furthermore, Ni-Al spinels with 4, 5, and 6 mol % Ni were investigated in the dry reforming of CH4 (DRM) with CO2 to produce H2 and CO. CH4 conversions near the thermodynamic equilibrium were observed depending on the Ni content and reaction temperature. The Ni catalysts were further compared to a noble metal-containing catalyst based on a spinel system showing comparable CH4 conversion and carbon selectivity in the DRM.