Thermodynamic sensitivity analysis of CO₂ reforming of methane based on equilibrium predictions

Abstract

Thermodynamic sensitivity analysis was conducted to evaluate the selectivity dry reforming of methane (DRM) with respect to other competing side reactions in terms of Gibbs energy minimization and equilibrium reactor compositions. Spontaneity of each reaction was evaluated by their corresponding changes in Gibbs energy as a function of reactor temperature from 100 – 1000 °C. At temperatures above 700 °C, all reactions considered with the exception of the Boudouard reaction are spontaneous due to their negative deltaG values. Equilibrium compositions were computed for 40 kmol of feed (CO2 + CH4) to determine its sensitivity to occurrence of reverse water-gas-shift (RWGS) reaction and changes in feed CO2/CH4 ratio. The presence of RWGS reaction results to higher reactant conversion accompanied by more severe carbon formation. The H2/CO ratio was however not affected by its occurrence. At CO2/CH4 feed ratio of 2, the product ratio was barely affected and at minimal carbon formation while CO2/CH4 ratio value of 0.5 produced a lot of carbon especially at high temperatures due to the prevalence of CH4 cracking. DRM is thus more preferable at temperatures above 700 °C, devoid of RWGS and high feed CH4.

Dry Reforming of Methane over Rare-Earth Metal Oxide Ni–M–Al (M = Ce, La) Catalysts

“…1.2 over Ni/LaAlO 3 during DRM at 700 °C using a GHSV of 18 L/(g·h) at a TOS of 10 h. This H 2 /CO value is the same as in the current case over 15Ni–15La–20Al at 700 °C. Thermodynamic analysis in ref gave a H 2 /CO ratio of ca. 1.1 at 800 °C, close to those obtained in the current work.…”

Improving the Performance of Gliding Arc Plasma-Catalytic Dry Reforming Via a New Post-Plasma Tubular Catalyst Bed

“…The Boudouard reaction (2CO→C + CO 2 , ΔH 0 = − 172kJ/mol) is another key side reaction. This reaction is expected to be less favored above 700 • C due to the positive Gibbs free energy change, which indicates a shift in favorability towards methane decomposition at higher temperatures [59][60][61]. The high CO selectivity (100%) observed below 600 • C suggests limited occurrence of the Boudouard reaction, likely due to high CO 2 /CO ratios at low CO 2 conversions and/or kinetic limitations, as shown in Table S1.…”

In situ study of low-temperature dry reforming of methane over La2Ce2O7 and LaNiO3 mixed oxides

“…The multiplets with binding energy v (882.6 eV) and v II (888.6 eV) are due to the shake-down process and correspond to Ce 3d 9 J o u r n a l P r e -p r o o f 13 4f 2 O 2p 4 and Ce 3d 9 4f 1 O 2p 5 final states, respectively [45,47]. AlCeO 3 was used as a reference material for Ce 3+ , which was deconvolved in two doublets: v 0 (880.5 eV) and v I (884.6 eV), corresponding to the final states Ce 3d 9 4f 1 O 2p 6 and Ce 3d 9 4f 2 O 2p 5 , respectively [47,67,68]. The labels follow the convention established by Burroughs et.…”

“…2) [4]. CH J o u r n a l P r e -p r o o f 3 DRM presents two main challenges: i) thermal degradation of the catalyst and/or support due to the highly endothermic nature of the reaction, which requires elevated temperature (typically above 700 °C) to reach high carbon monoxide and hydrogen yields [1,5]; ii) carbon deposition on the catalyst (equations 3 and 4), leading to deactivation [4].…”