Activation Pathway of C‐H and C–C Bonds of Ethane by Pd Atom with CO₂ as a Soft Oxidant

Abstract

Ethane and CO2 can be converted to synthesis (CO and H2) via the dry reforming pathway and formed important industrial raw material ethylene through oxidative dehydrogenation pathway, which are relating to the C−C bond and C−H bond cleavage, respectively. In this study, density functional theory was used to study the activation reaction of ethane C−H bond, C−C bond on Pd atom with CO2 as oxidant. CH3CH3→CH2CH3+H→CH2CH2+2H is the dominant path for dehydrogenation to ethylene. Adding an appropriate amount of H2 can reduce the deep dehydrogenation of ethylene and increase the selectivity. Under the condition of 873 K with Pd atom as catalyst, it is more inclined to ethane/CO2 reforming reaction. The main route for generating CO is CH3CH2+H→CH3+CH3→CH2→CHOH→CHO→CO. H atoms are conducive to the activation of CO2, CO2+H→COOH→CO+OH is the dominant reaction pathway for CO2 activation. The first reaction in the whole system is the first C−H bond cleavage of ethane.

Selective catalytic and kinetic studies on oxydehydrogenation of ethane with CO2 over lanthanide metal catalysts

“…C 2 H 6 conversion increases with the increase of temperature, but CO 2 conversion is always 0, so CO 2 does not participate in the gas phase non-catalytic reaction. Therefore, it can be inferred that the essence of the homogeneous reaction is the coupling of ethane pyrolysis and ethane hydrogenolysis (reaction 12-13) [34][35][36][37]; the results of this study are similar to Xu et al [38]:…”

Oxidative Dehydrogenation of Ethane with CO2 as a Soft Oxidant over a PtCe Bimetallic Catalyst

“…An example is the use of CO 2 as a soft oxidant to enhance the efficiency of the target product synthesis. , In particular, oxidative ethane dehydrogenation (OED) with CO 2 can increase the equilibrium ethane conversion by H 2 removal via the reverse water gas shift reaction ( r WGS) . Another benefit of CO 2 is the removal of coke formed on the catalyst via the reverse Boudouard reaction (CO 2 + C s ⃗ 2CO), which can also enhance the catalyst stability. , However, CO 2 addition typically reduces ethylene selectivity because CO 2 may react with ethane via two distinct pathways: (1) oxidative dehydrogenation (C 2 H 6 + CO 2 ⃗ C 2 H 4 + CO + H 2 O) and (2) dry reforming (C 2 H 6 + 2CO 2 ⃗ 4CO + 3H 2 ). − The former reaction proceeds via the scission of the C–H bond to yield ethylene, while syngas ( i.e. , CO and H 2 ) is produced by breaking the C–C bond. , Thermodynamic calculations have suggested that both reactions can occur simultaneously at temperatures of ≥823 K, yielding both dehydrogenation products (ethylene) and reforming products (syngas) .…”

Distribution and change of China’s population on the terrain gradients from 2000 to 2020

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