CNT‐Catalyzed Oxidative Dehydrogenation of Ethylbenzene to Styrene: DFT Calculations Disclose the Pathways

Abstract

Oxygen atoms, in the form of epoxy or carbonyl groups present at the edges of carbon nanotubes, trigger oxidative dehydrogenation of ethylbenzene to styrene. DFT calculations reveal that the process can occur along three pathways. The first two bifurcate from the initial transformation of an epoxide into a hydroxyl group, which occurs via a biradical transition state and the formation of a benzyllike intermediate. The epoxide can further react to release styrene and form a water molecule, as observed experimentally, via a highly exothermic process. Alternatively, in the presence of a second adjacent epoxide, styrene is also produced without water formation along a less exothermic pathway that leaves two hydroxyl groups on the nanotube surface. Along the third pathway, two adjacent carbonyl groups (quinone functionality) also promote the formation of styrene, with energy barriers similar to those calculated in the presence of epoxy groups. These are in the range 36-37 kcal mol À1 . These values that can be easily surmounted at the working temperature used in the experiment (between 450 and 550 8C).[a] Dr.

Synthesis and applications of graphene and graphene-based nanocomposites: Conventional to artificial intelligence approaches

“…Graphene and its composites are extensively employed in several catalyst-supported reactions, such as the oxygen reduction reaction (ORR) (Kamat, 2010;Lei et al, 2014), due to the aforementioned unique features, Fischer-Tropsch synthesis (FTS) (Berger et al, 2004;Pereira et al, 2004;Marforio et al, 2019), oxidative dehydrogenation (ODH) of ethylbenzene to styrene, oxidation of SO 2 gas to SO 3 (Long et al, 2011), oxidative dehydrogenation (ODH), (Lu et al, 2016), water splitting (Choi et al, 2010;Guo and Dong, 2011), selective hydrogenation (Srivastava et al, 2010), oxidative dehydrogenation (ODH) of ethylbenzene to styrene (Mestl et al, 2001;Su et al, 2005;Hass et al, 2008;Wang et al, 2019a), NOx abatement (Kim et al, 2009), catalytic purification of VOCs (Peng et al, 2010), hydrogen fuel cells (Seger and Kamat, 2009), and wastewater treatment (Dadvar et al, 2017) are only a few examples of graphene applications. There are wide applications of graphene nanomaterials, which is twodimensional lattice structure with a hexagonal comb composed of carbon atoms and sp 2 hybrid orbitals.…”

“…Including possible solutions, flexibility, low cost, light weight, and large area coatings are all the considerable advantages that have gained interest regarding solar cells which are based on bulk heterojunction (BHJ) (Günes et al, 2007;. BHJ absorbs solar light efficiently because it consists of a mixture of polymer materials that are electron donors and acceptors, which dissociate into free charge carriers while generating excitons (van Hal et al, 2003;Xiao et al, 2018;Marforio et al, 2019).…”