Herwig Jan, Titus Juliane, Kullmann Jens, Wilde Nicole, Hahn Thomas, Gläser Roger, Enke Dirk
Institute of Chemistry, Martin-Luther-University Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany.
Institute of Chemical Technology, University of Leipzig, Linnéstraße 3, 04103 Leipzig, Germany.
ACS Omega. 2018 Jan 30;3(1):1201-1212. doi: 10.1021/acsomega.7b01621. eCollection 2018 Jan 31.
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, NiAlO and CoAlO, 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 m·g and 25 to 94 m·g 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 CH (DRM) with CO to produce H and CO. CH 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 CH conversion and carbon selectivity in the DRM.
提高催化剂的活性和稳定性是当今科学研究中的一项重大挑战。先前的研究表明，额外孔系统的产生会影响多孔催化剂在活性、选择性和稳定性方面的催化性能。本研究聚焦于通过环氧化物介导的溶胶-凝胶法合成具有尖晶石相结构、分级孔结构且镍和钴含量相对于总金属含量为3%至33%的混合金属氧化物NiAlO和CoAlO。溶胶-凝胶过程伴随着聚合诱导相分离以引入额外的孔系统。对所获得的混合金属氧化物进行了孔形态、表面积和尖晶石相形成方面的表征。对于镍和钴，Brunauer-Emmett-Teller表面积分别在74至138 m²/g和25至94 m²/g范围内。基于相分离的大孔直径在500至2000 nm之间，镍基体系的中孔直径为10 nm，钴尖晶石的中孔直径在20至25 nm之间。此外，研究了含4%、5%和6%镍的Ni-Al尖晶石在CH₄与CO的干重整反应中生成H₂和CO的情况。根据镍含量和反应温度观察到接近热力学平衡的CH₄转化率。将镍催化剂与基于尖晶石体系的含贵金属催化剂进行了进一步比较，后者在干重整反应中显示出相当的CH₄转化率和碳选择性。
