Stability evaluation of ethanol dry reforming on Lanthania‐doped cobalt‐based catalysts for hydrogen‐rich syngas generation

Abstract

Summary Catalytic stability with time‐on‐stream is an important aspect in ethanol dry reforming (EDR) since catalysts could encounter undesirable deterioration arising from deposited carbon. This work examined the promotional effect of La on 10%Co/Al2O3 in terms of activity, stability, and characteristics. Catalysts were characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman, and X‐ray photoelectron spectroscopy (XPS) measurements whilst catalytic EDR performance of La‐promoted and unpromoted 10%Co/Al2O3 prepared via wet impregnation technique was investigated at 973 K for 72 h using a stoichiometric feed ratio (C2H5OH/CO2 = 1/1). La promoter substantially enhanced both metal dispersion and metal surface area from 0.11% to 0.64% and 0.08 to 0.43 m2 g−1, respectively. Ethanol and CO2 conversions appeared to be stable within 50 to 72 h after experiencing an initial activity drop. The conversion of C2H5OH and CO2 for La‐promoted catalyst was about 1.65 and 1.34 times greater than unpromoted counterpart in this order. The carbonaceous deposition was considerably decreased from 55.6% to 36.8% with La promotion due to La2O2CO3 intermediate formation. Additionally, 3%La‐10%Co/Al2O3 possessed greater oxygen vacancies acting as active sites for CO2 adsorption and hence increasing carbon gasification. Even though graphitic and filamentous carbons were formed on used catalyst surface, La‐addition diminished graphite formation and increased the reactiveness of amorphous carbon.

CO2 Reforming of Ethanol: Density Functional Theory Calculations, Microkinetic Modeling, and Experimental Studies

“…According to our calculations, CH Dry reforming is a high-temperature chemical process 57 with a typical reaction temperature of 700−800 °C for ethanol conversion. 3,[5][6][7][9][10][11]13 To correlate to experiments, thermodynamic contributions, including zero-point energy (ZPE), internal energy correction (U), and entropies (S) (see Table S2), were considered to obtain the Gibbs activation/reaction energy of each elementary step, where the experimental temperature of 973.15 K was used. As shown in Table 1, the thermodynamic corrections to activation/reaction energies are rather small for most cases, usually below 0.1 eV.…”

“…To reduce energy consumption and suppress undesired reactions, solid catalysts with favorable activity, selectivity, and stability are necessary and crucial in chemical transformations. In recent years, experimental efforts have been made to improve catalytic performance from several aspects, including changing active metal catalysts, screening oxide supports, tuning metal–oxide interaction, as well as modifying catalyst composition and morphology. − Supported Cu, Ni, Ir, Rh, and Co catalysts were reported for EDR, especially Ni and Rh were mostly studied. It was reported that Ni/CeO 2 is an active and stable catalyst for reforming reactions. ,, Indeed, the redox properties of CeO 2 facilitate CO 2 dissociation and hinder C accumulation over metal catalysts. , In addition, Rh/oxide and Rh/mixed metal oxide catalysts also show good activity in EDR. ,, It was reported that the metal catalyst in the metal/oxide system is responsible for the C–C rupture in ethanol .…”

Fibrous spherical Ni‐M/ZSM‐5 (M: Mg, Ca, Ta, Ga) catalysts for methane dry reforming: The interplay between surface acidity‐basicity and coking resistance

“…Synthesis gas (syngas), a versatile feedstock, has been widely used in the chemical industry as a starting material for the production of liquid energy carriers and high value‐added chemicals . One of the environmentally benign pathways for syngas production is dry reforming of methane (DRM): CH 4 + CO 2 ⇌2CO + 2H 2 , ΔH o 298 K = 260.5 kJ mol −1 .…”

“…Due to its endothermicity, high temperature is required to reach suitable CH 4 and CO 2 conversions. Thus far, nickel‐based materials have demonstrated high DRM performance from an industrial perspective due to their high activity, availability and low cost . However, there suitability to loss of activity and heavy carbon deposition due to sintering at harsh reaction conditions, leading to abrupt and massive deactivation of catalysts, remains an intractable problem.…”

Hydrogen‐rich syngas production from chemical looping steam reforming of bio‐oil model compound: Effect of bimetal on LaNi 0.8 M 0.2 O 3 (M = Fe, Co, Cu, and Mn)

“…The results demonstrated that the doping metal can change the characteristic of coke deposition. Fayaz et al investigated ethanol dry reforming for hydrogen‐rich syngas on Lanthania‐doped cobalt‐based. The La promoter enhanced both metal dispersion and metal surface area and promoted production of hydrogen.…”