Hydrogen assisted catalytic combustion of methane on platinum
TL;DR: In this article, the authors measured the exit temperatures of methane/hydrogen/air mixtures flowing at atmospheric pressure through platinum coated honeycomb channels and investigated a single channel of this monolith by a two-dimensional Navier-Stokes simulation including an elementary-step surface reaction mechanism.
About: This article is published in Catalysis Today.The article was published on 2000-06-10. It has received 333 citations till now. The article focuses on the topics: Hydrogen purifier & Methane reformer.
Citations
More filters
TL;DR: In this article, a review of the development of micro-power generators by focusing more on the advance in fundamental understanding of microscale combustion is presented, and the conventional concepts of combustion limits such as flammability limit, quenching diameter, and flame extinction and heat recirculation are revisited.
621 citations
TL;DR: In this paper, a review of the use of catalysts for methane combustion in high temperature natural gas-turbines can be found, where a large amount of work has been undertaken to develop catalysts both for controlling methane emission as well as for generating power.
Abstract: The important greenhouse effect of methane (more than an order of magnitude greater than CO2) makes it essential to eliminate/control the methane emission from natural gas engines/power plants and petroleum industries. Catalytic combustion of methane is favored over homogeneous combustion, because the former greatly facilitates the oxidative destruction of methane. Moreover, use of catalysts for methane combustion in gas-turbines affords lower working temperatures (as compared to gas-fired turbines) and thermodynamically limits NOx (which is an extremely harmful environmental pollutant) emission. A large amount of work has been undertaken to develop catalysts both for controlling methane emission as well as for generating power in high temperature natural gas-turbines. This review will address the different issues related to the variety of catalysts which have been employed for methane/lower alkane combustion. Although all the related important aspects of the combustion catalysts will be addressed, greater emphasis will be placed on recent work in this field.
599 citations
01 Jan 2011
TL;DR: A review of research and development on micro and mesoscale combustion is presented in this article, with an emphasis on fundamental understandings achieved in the field during the last decade, due to its small scale nature, increasing effects of flame-wall interaction and molecular diffusion.
Abstract: A review of research and development on micro and mesoscale combustion is presented, with an emphasis on fundamental understandings achieved in the field during the last decade. Due to its small scale nature, increasing effects of flame–wall interaction and molecular diffusion are the characteristic features of micro and mesoscale combustion. After brief review of device developments, overview of fundamentals in micro and mesoscale combustion as well as possible future directions is presented.
361 citations
TL;DR: A review of recent progress in the various classes of heterogeneous catalysts for methane combustion can be found in this paper, where the authors provide guidance for researchers with interests ranging from the field of heterogenous catalysis to the engineering of new high performance materials in environmental and chemical engineering.
Abstract: This invited review highlights recent progress in the various classes of heterogeneous catalysts for methane combustion. These combustion catalysts provide a high-efficiency, clean energy source for natural gas vehicles and power plants. This review examines bimetallic systems, and a variety of oxides including single metal oxides, perovskites, spinels, and hexaaluminates. Noble metal mixed oxides exhibit superior catalytic activity due material-specific supports, additives, preparation methods, poisoning, regeneration and surface structure. Kinetic aspects, mechanisms, and the latest studies concerning density functional theory modelling are discussed in conjunction with particle oxidation/reduction mechanisms. The extensive background knowledge on the methane combustion reaction provided by this review provides guidance for researchers with interests ranging from the field of heterogeneous catalysis to the engineering of new high performance materials in environmental and chemical engineering.
198 citations
01 Jan 2015
TL;DR: The role of laser diagnostics in combustion science and technology is discussed in this article, where the focus is on using optical diagnostics to probe thermal, fluidic, and chemical properties of head-on and sidewall quenching.
Abstract: This review discusses the role of laser diagnostics in combustion science and technology. In its first part, it may guide understanding of advanced diagnostic methods, and is particularly helpful for non-specialized experimentalists. Various challenges for future developments and applications of optical combustion diagnostics are highlighted. In the second part of this review, flame-wall interactions are selected for a more in-depth discussion. Flame-wall interactions are scientifically interesting and are of great importance to any enclosed practical combustion process. Following a description of current understanding, the focus is on using optical diagnostics to probe thermal, fluidic, and chemical properties of head-on and sidewall quenching. The review ends with a discussion of issues and implications for future experimental research and specific diagnostic needs.
155 citations
References
More filters
[...]
22 Apr 1998
1,322 citations
"Hydrogen assisted catalytic combust..." refers methods in this paper
...Figure 3: Typical experimental setup to study catalytic combustion in a stagnation flow configuration (left, [6]) and sketch of the model as used in the present paper (right)....
[...]
...The reaction scheme shown in Table 1 was developed to model ignition of catalytic hydrogen, carbon monoxide, and methane combustion [1, 6, 9-11] and is used here without modification....
[...]
TL;DR: In this article, a 19-elementary-step model of adsorption, desorption and surface reaction steps with reaction parameters from the literature or from fits to previous experiments was used to simulate the direct oxidation of CH4 to H2 and CO in O2 and in air at high temperatures over alumina foam monoliths.
Abstract: The direct oxidation of CH4 to H2 and CO in O2 and in air at high temperatures over alumina foam monoliths coated with high loadings of Pt and Rh has been simulated using a 19-elementary-step model of adsorption, desorption and surface reaction steps with reaction parameters from the literature or from fits to previous experiments. The surface reaction model for Pt is in good agreement with previously reported low-pressure(0.1 to 1 torr) reactor measurements of CH4 oxidation rates at temperatures from 600 to 1,500 K and of OH radical desorption during CH4 oxidation at 1,300 to 1,600 K over polycrystalline Pt foils. The model predictions for both catalysts are also consistent with product selectivities observed over monolithic catalysts in an atmospheric-pressure laboratory-scale reactor, and the differences between Pt and Rh can be explained by comparing individual reaction steps on these surfaces. Because of the good agreement between the model and both low-and atmospheric-pressure reactor simulations, a complete energy diagram for methane oxidation at low coverages is proposed. The model results show that under CH4rich conditions at high temperatures, H2 and CO are primary products of the direct oxidation of methane via a pyrolysis mechanism.
350 citations
TL;DR: In this paper, a tube wall catalytic reactor was simulated as a model for a single pore of the monolithic catalyst using a 2-D flow field description coupled with detailed reaction mechanisms for surface and gas-phase chemistry.
Abstract: Partial oxidation of methane in monolithic catalysts at very short contact times offers a promising route to convert natural gas into syngas (H2 and CO), which can then be converted to higher alkanes or methanol. Detailed modeling is needed to understand their complex interaction of transport and kinetics in these systems and for their industrial application. In this work, the partial oxidation of methane in noble-metal (Rh and Pt)-coated monoliths was studied numerically as an example of short-contact-time reactor modeling. A tube wall catalytic reactor was simulated as a model for a single pore of the monolithic catalyst using a 2-D flow field description coupled with detailed reaction mechanisms for surface and gas-phase chemistry. The catalytic surface coverages of adsorbed species are calculated vs. position. The reactor is characterized by competition between complete and partial oxidation of methane. At atmospheric pressure, CO2 and H2O are formed on the catalytic surface at the entrance of the catalytic reactor. At higher pressure, gas-phase chemistry becomes important, forming more complete oxidation products downstream and decreasing syngas selectivity by about 2% at 10 bar. Temperature (from 300 to ∼ 1,200 K), velocity, and transport coefficients change very rapidly at the catalyst entrance. The dependence of conversion and selectivity on reactor conditions was examined.
245 citations
TL;DR: In this paper, the catalyzed combustion of lean hydrogen-oxygen mixtures in a stagnation flow over a platinum surface and in a flat-plate boundary layer is analyzed. But the results of the analysis are limited.
176 citations
TL;DR: In this paper, the authors studied catalytic ignition of mixtures of H2 + O2 by measuring and simulating the temporal evolution from the kinetically controlled regime (i.e., prior to ignition) to the state controlled by mass transport after ignition.
132 citations