This paper presents a method for the quantification of gas streams from reactive systems using on-line gas chromatography. The method is based on the mathematical development of correlations between the quantities detected by a set comprised of a thermal conductivity detector, a methanizer, and a flame ionization detector. The method allows for a complete and physically meaningful quantification of the composition of gas streams.<br>

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.

Quantification of the gas streams from chemical systems such as catalytic reactors are routinely performed by on-line chromatography. Gas chromatographs used for this purpose are typically provided with a combination of thermal conductivity (TCD) and flame ionization (FID) detectors to be able to detect and quantify both permanent gases and hydrocarbons. However, the accuracy of the quantification is hindered by the intrinsic limitations of each type of detector. Namely, TCD has low sensitivity and FID does not detect permanent gases; COx, N2, H2, etc. Therefore, modern gas chromatographs include methanizer units to partially overcome this shortcoming by converting COx to methane. However, as far as these authors know, the literature has not presented an analytical method to characterize gas streams with high accuracy by the simultaneous use of a combination of a TCD-FID detection system provided with a methanizer. In this work, we developed analytical methods for this purpose. Our approach consisted on formulating a mathematical model for the well-known external and internal standard quantification methods in gas chromatography. We specifically applied the methodology to the analysis of the gas streams from a catalytic reactor performing the combustion of methane. We found that the commonly applied external standard method leads not only to inaccurate quantification but also to physically meaningless conclusions on the behavior of the selected model system. In contrast, the internal standard method led to a highly accurate quantification with a physical meaning. Considering these findings, our contribution also draws attention to the need for a thoughtful application of chromatographic methods when studying the reactivity of gas systems.

The dry reforming of methane is a promising technology for the abatement of CH₄ and CO₂. Solid solution Ni–La oxide catalysts are characterized by their long–term stability (100h) when tested at full conversion. The kinetics of dry reforming over this type of catalysts has been studied using both power law and Langmuir–Hinshelwood based approaches. However, these studies typically deal with fitting the net CH₄ rate hence disregarding competing and parallel surface processes and the different possible configurations of the active surface. In this work, we synthesized a solid solution Ni–La oxide 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 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 <a>metal−oxygen </a>pair site; (2) this model predicted the existence of a nearly saturated nickel surface with chemisorbed oxygen adatoms derived from the dissociation of CO₂; (3) the dissociation of CO₂ can either be an inhibitory or an irrelevant step, and it can also modify the apparent activation energy for CH₄ 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.

The dry reforming of methane is a promising technology for the abatement of CH₄ and CO₂. Solid solution Ni–La oxide catalysts are characterized by their long–term stability (100h) when tested at full conversion. The kinetics of dry reforming over this type of catalysts has been studied using both power law and Langmuir–Hinshelwood based approaches. However, these studies typically deal with fitting the net CH₄ rate hence disregarding competing and parallel surface processes and the different possible configurations of the active surface. In this work, we synthesized a solid solution Ni–La oxide 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 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 <a>metal−oxygen </a>pair site; (2) this model predicted the existence of a nearly saturated nickel surface with chemisorbed oxygen adatoms derived from the dissociation of CO₂; (3) the dissociation of CO₂ can either be an inhibitory or an irrelevant step, and it can also modify the apparent activation energy for CH₄ 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.

This paper presents a method for the quantification of gas streams from reactive systems using on-line gas chromatography. The method is based on the mathematical development of correlations between the quantities detected by a set comprised of a thermal conductivity detector, a methanizer, and a flame ionization detector. The method allows for a complete and physically meaningful quantification of the composition of gas streams.<br>