Dry reforming of CH4 on Co/Al2O3 catalysts reduced at different temperatures

Abstract

Keywords:Dry reforming of CH4 Co/Al2O3 catalyst XPS of Co/Al2O3 Surface carbon a b s t r a c t The reforming of methane with carbon dioxide has been investigated at 773 K on 10% Co/Al 2 O 3 reduced at different temperatures up to 1173 K. The catalysts were characterized by BET, TPR, XRD and XPS methods. TPR and XPS results revealed that during the pre-treatment of the catalysts the Co only partially reduced. The reduction degree and the amount of the structured metallic cobalt increased with the reduction temperature. The conversion of the reactants was the highest on the sample reduced at 973 K, but the turnover frequencies of CO and H 2 formation increased as the reduction temperature increased.The amount of surface carbon significantly depended on the pre-treatment temperature of the catalysts. The IR spectra registered at the beginning of the reaction indicate that tilted CO was formed, but the position of the absorption bands depends on the reduction temperature of the catalysts. Similarly, the pre-treatment temperature influenced the type of the surface carbon determined by XPS. We assume that the different structures of the metallic Co formed in pretreatment resulted in the different catalytic behaviors.

How do Core–Shell Structure Features Impact on the Activity/Stability of the Co‐based Catalyst in Dry Reforming of Methane?

“…[18] The result was accordance with our observation that structural variation from b-Co to a-Co could occuru nder the reaction conditions. [18] The result was accordance with our observation that structural variation from b-Co to a-Co could occuru nder the reaction conditions.…”

“…As for 11.1-Co@SiO 2 -6.0 ( Figure 5a), besides the peaks at 778.0 and 780.1 eV,a dditional peaks at 782.9 and 785.7 eV appear, and they can be attributed to the Co species with mediumo r strong core-shell interaction, respectively.C learly,t he XPS data are compiled well with the H 2 -TPR results. [18] In the currents tudy,t he Co 0 fraction increases with increasing core particle size, and this is expected because the bulky Co 3 O 4 cores are readily reduced asi llustrated in the H 2 -TPR investigation. Horvµth et al reported that the Co 0 fraction was only 0.57 even if the Co 3 O 4 / Al 2 O 3 precursor was subjected to ap re-reductiona t9 00 8C.…”

Development of Co Supported on Co−Al Spinel Catalysts from Exsolution of Amorphous Co−Al Oxides for Carbon Dioxide Reforming of Methane

“…Recent studies on the application of common support materials for Co and Ni catalysts in dry reforming have demonstrated that the performance of support decreased in the order of Al 2 O 3 >MgO>SiO 2 >ZrO 2 >TiO 2 . The superior activity of Al 2 O 3 and MgO is most likely resulted from their strong metal‐support interaction, providing several advantages such as improve catalyst stability, prevent active metal sintering and promote CO 2 conversion . Particularly, Co supported on Al 2 O 3 catalysts have constituted an important class of catalytic materials and have been widely examined owing to their high abundancies, excellent catalytic activities, and good resistance towards carbon deposition .…”

“…[1,7,20,21] The superior activity of Al 2 O 3 and MgO is most likely resulted from their strong metal-support interaction, providing several advantages such as improve catalyst stability, prevent active metal sintering and promote CO 2 conversion. [6,7,20,22,23] Particularly, Co supported on Al 2 O 3 catalysts have constituted an important class of catalytic materials and have been widely examined owing to their high abundancies, excellent catalytic activities, and good resistance towards carbon deposition. [24] Al 2 O 3 is able to induces high dispersion of the Co metal to prevent the sintering of active sites, thereby preserving the activity of Co. [25,26] With reference to Co/Al 2 O 3 catalysts, different preparation methods and metal loadings have been examined to yield catalysts with diverse structures and reactivities toward dry reforming.…”

“…For instance, CoAl 2 O 4 spinel is often found on Co/Al 2 O 3 catalysts after undergoing a reaction conducted at temperatures > 700°C, owing to the oxidation of Co by CO 2 and the reaction with Al 2 O 3 . [48] Horváth et al [22] has also reported the possibility of CoAl 2 O 4 formation during pretreatment of catalysts. The transformation of Co into CoAl 2 O 4 renders it less reactive towards the reaction with CH 4 and CO 2 , resulting in reduction of CH 4 and CO 2 conversion over time.…”