Kinetic Assessment of the Dry Reforming of Methane over a Ni–La₂O₃Catalyst

Abstract

The dry reforming of methane is a promising technology for the abatement of CH 4 and CO 2 . Ni−La 2 O 3 catalysts are characterized by their long-term stability (100 h) when tested at full conversion. The kinetics of dry reforming over these types of catalysts has been studied using both power-law and Langmuir− Hinshelwood-based approaches. However, these studies typically deal with fitting the net CH 4 rate, hence disregarding competing and parallel surface processes and the different possible configurations of the active surface. In this work, we synthesized a Ni−La 2 O 3 catalyst and tested six Langmuir−Hinshelwood mechanisms considering both single and dual active sites for assessing the kinetics of dry reforming and the competing reverse water−gas shift reaction and investigated the performance of the derived kinetic models. In doing this, it was found that: (1) all of the net rates were better fitted by a single-site model that considered that the first C−H bond cleavage in methane occurred over a metal−oxygen pair site; (2) this model predicted the existence of a nearly saturated nickel surface with chemisorbed oxygen adatoms derived from the CO 2 dissociation; (3) the CO 2 dissociation can either be an inhibitory or an irrelevant step, and it can also modify the apparent activation energy for CH 4 activation. These findings contribute to a better understanding of the dry reforming reaction's kinetics and provide a robust kinetic model for the design and scale-up of the process.

Light-driven efficient dry reforming of methane over Pt/La2O3 with long-term durability

“…The disassociation of C–H bonds in the methane molecule is the rate-determining step of the DRM. 31 CH 4 -TPSR and CO 2 -TPSR were operated on Pt/La 2 O 3 under irradiation or in dark to elucidate why light irradiation played a crucial role in augmenting the catalytic activity and selectivity (Fig. 5c and d).…”

“…3a over Pt/La 2 O 3 -U and Pt/La 2 O 3 -S-U, according to the reaction of La 2 O 3 and CO 2 to produce intermediate La 2 O 2 CO 3 (La 2 O 3 + CO 2 ¼ La 2 O 2 CO 3 ). 30,31 XPS was performed to evaluate the variation in valence and chemical interaction. The XPS spectra of Pt show that the peak of Pt 0 on Pt/La 2 O 3 appears at a higher B.E.…”

“…45,46 In addition, the formation of La 2 O 2 CO 3 facilitates the elimination of carbon species from the metal surface. 31 The symmetric and asymmetric deformation vibrations of adsorbed -CH 3 groups present at ca. 1354 cm À1 or 1341 cm À1 aer CH 4 and CO 2 are introduced, showing that CH 4 is dissociated into -CH 3 and H species.…”

Interface of Ni-MgCr2O4 Spinel Promotes the Autothermal Reforming of Acetic Acid through Accelerated Oxidation of Carbon-Containing Intermediate Species

“…Hydrogen can be extracted via reforming processes of HAc via three major routes: steam reforming (SR), catalytic partial oxidation (CPOX), and autothermal reforming (ATR), as listed in eqs –. In contrast to endothermic SR with the requirement of high external heat energy and exothermic CPOX with a low hydrogen yield, the ATR process, which balances the reaction heat through regulating oxygen in feed, presents a higher energy efficiency and shows economical preferability. , CH 3 COOH + 2 normalH 2 normalO → 2 CO 2 + 4 normalH 2 , 0.25em normalΔ H = 131.4 0.25em kJ / mol CH 3 COOH + normalO 2 → 2 CO 2 + 2 normalH 2 , 0.25em normalΔ H = prefix− 350.6 0.25em kJ / mol CH 3 COOH + 1.44 normalH 2 normalO + 0.28 normalO 2 nobreak→ 2 CO 2 + 3.44 normalH 2 , newline0.25em normalΔ H nobreak= 0 0.25em kJ / mol Nonprecious metal catalysts, such as nickel-based catalysts, have been widely investigated due to their excellent activity in cleavage of C–C and C–H bonds within hydrocarbons for the reforming process. −…”

Instant Fingerprint Discrimination for Military Explosive Vapors by Dy3+ Doping a La2O3-Based Cataluminescence Sensor System

“…In the CTL sensing system, nanomaterial as a sensing element plays a decisive role in the distinct catalytic oxidation process of compounds due to different catalytic activities. − Lanthanum oxide (La 2 O 3 ), containing a class of elements possessing unique optical, catalytic, and magnetic properties on account of the unique configuration of the 4f electrons, has been explored for numerous applications in superconductors, optoelectronic devices, biosensors, and catalysts . Excellent chemical and thermal stability, low toxicity, reduced oxide leakage current, and greater voltage range make La 2 O 3 a potential candidate for constructing environmentally benign sensors for a variety of pollutants. , In addition, it has been proposed that ion doping , is an effective strategy to generate oxygen vacancies in a lattice, which provides a more feasible path for ion transport. Meanwhile, the surface defect states on metal oxides have a promoting effect on enhancing the interaction between molecules and materials at the gas–solid interface.…”