A Mesoporous Cobalt Aluminate Spinel Catalyst for Nonoxidative Propane Dehydrogenation

Abstract

A mesoporous CoAl2O4 spinel (Co‐Al) is synthesized by a one‐step evaporation‐induced self‐assembly (EISA) method. N2 physisorption and TEM are used to demonstrate the presence of mesopores within the Co‐Al material. The spinel crystal structure of Co‐Al, in which Co occupies tetrahedral (Td) sites, is confirmed by using XRD and UV/Vis spectroscopy. In nonoxidative propane dehydrogenation at 550 °C, a propane conversion of approximately 8 % is observed for Co‐Al with a >80 % propylene selectivity, which corresponds to a turnover frequency of 5.1 h−1 based on an estimation of the number of active Co sites by using NH3 temperature‐programmed desorption. A much higher propane conversion rate and a circa 80 % propylene selectivity is observed upon reaction at 600 °C. Continuous deactivation of the catalyst is observed for Co‐Al at this elevated temperature. In situ X‐ray absorption spectroscopy results suggest that Co remains as a Td Co2+ species under the reaction conditions. The Td Co2+ sites within the Co‐Al material are thus proposed to act as Lewis acidic active sites; this acidity is verified using IR spectroscopy with pyridine as a probe molecule.

CHITOSAN-TEMPLATED LIGHTWEIGHT SPINEL CoAl2O4 NANOFIBRIL AEROGELS

“…The large space of the CoAl 2 O 4 aerogels was occupied by air leads to a lightweight thermal material, which has the potential to thermal insulation. Due to the abundant availability of active catalytic sites of aluminum and cobalt in the oxide composites, the CoAl 2 O 4 aerogels may be a promising catalyst support for various oxidation and reduction reactions [8]. High surface area and large porosity can easily access secondary components to the aerogel networks to accelerate the reaction performance of magnetic CoAl 2 O 4 -based nanocomposites [6].…”

“…Cobalt aluminates (CoAl 2 O 4 ) is an important ceramic of the normal spinel aluminate family with aluminum in octahedral sites and cobalt in tetrahedral ones [6]. Porous CoAl 2 O 4 nanomaterial is used as a blue pigment component for preparing colorful magnetic ceramics [7] and catalyst supports [8]. The crystallinity, nanoscale, and porosity of alumina are the most critical structured features to determine its reaction performance.…”

Highly Effective Direct Dehydrogenation of Propane to Propylene by Microwave Catalysis at Low Temperature over Co−Sn/NC Microwave Catalyst

“…reported that single‐site Co 2+ /SiO 2 exhibits selectivity >95 % at 550 °C and >90 % at 650 °C with stable activity over 24 h in the selective propane dehydrogenation. On the other hand, mesoporous CoAl 2 O 4 spinel showed higher conversion and selectivity at 600 °C owing to the well‐dispersed Co 2+ in the alumina matrix, which revealed the non‐redox type nature of cobalt coordinated with alumina as an active phase for propane dehydrogenation [13c] . Meanwhile, Sun et al [18] .…”

Cobalt‐Based Catalyst Supported on Different Morphologies of Alumina for Non‐oxidative Propane Dehydrogenation: Effect of Metal Support Interaction and Lewis Acidic Sites

“…However, this catalyst suffers from deactivation due to coke deposition and metal attrition, which requires frequent regeneration of the catalyst. [7] Sun et al, also studied the effect of different cobalt loading on alumina and found that 5 % loading of cobalt led to the formation of Co + 2 in the tetrahedral geometry and the higher percentage of cobalt loading led to cracking reaction. Indeed, this catalyst showed promising activity, but suffers from thermal sintering of the alumina support and possess environmental concern due to the presence of Cr (VI).…”

“…This was also supported using EXAFS study under reducing atmosphere and reaction condition. [7] Sun et al, also studied the effect of different cobalt loading on alumina and found that 5 % loading of cobalt led to the formation of Co + 2 in the tetrahedral geometry and the higher percentage of cobalt loading led to cracking reaction. [8] Indeed the addition of sulfate group reduces the reduction of CoO to metallic cobalt and also enhances CÀ H bond activation.…”