When will fossil fuel reserves be diminished

Catalytic partial oxidation of methane has been reviewed with an emphasis on the reaction mechanisms over transition metal catalysts. The thermodynamics and aspects related to heat and mass transport is also evaluated, and an extensive table on research contributions to methane partial oxidation over transition metal catalysts in the literature is provided. Presented are both theoretical and experimental evidence pointing to inherent differences in the reaction mechanism over transition metals. These differences are related to methane dissociation, binding site preferences, the stability of OH surface species, surface residence times of active species and contributions from lattice oxygen atoms and support species. Methane dissociation requires a reduced metal surface, but at elevated temperatures oxides of active species may be reduced by direct interaction with methane or from the reaction with H, H2, C or CO. The comparison of elementary reaction steps on Pt and Rh illustrates that a key factor to produce hydrogen as a primary product is a high activation energy barrier to the formation of OH. Another essential property for the formation of H2 and CO as primary products is a low surface coverage of intermediates, such that the probability of O–H, OH–H and CO–O interactions are reduced. The local concentrations of reactants and products change rapidly through the catalyst bed. This influences the reaction mechanisms, but the product composition is typically close to equilibrated at the bed exit temperature.

A review of catalytic partial oxidation of methane to synthesis gas with emphasis on reaction mechanisms over transition metal catalysts

Microscale combustion: Technology development and fundamental research

The microscopic spatial kinetic Monte Carlo (KMC) method has been employed extensively in materials modeling. In this review paper, we focus on different traditional and multiscale KMC algorithms, challenges associated with their implementation, and methods developed to overcome these challenges. In the first part of the paper, we compare the implementation and computational cost of the null-event and rejection-free microscopic KMC algorithms. A firmer and more general foundation of the null-event KMC algorithm is presented. Statistical equivalence between the null-event and rejection-free KMC algorithms is also demonstrated. Implementation and efficiency of various search and update algorithms, which are at the heart of all spatial KMC simulations, are outlined and compared via numerical examples. In the second half of the paper, we review various spatial and temporal multiscale KMC methods, namely, the coarse-grained Monte Carlo (CGMC), the stochastic singular perturbation approximation, and the τ-leap methods, introduced recently to overcome the disparity of length and time scales and the one-at-a time execution of events. The concepts of the CGMC and the τ-leap methods, stochastic closures, multigrid methods, error associated with coarse-graining, a posteriori error estimates for generating spatially adaptive coarse-grained lattices, and computational speed-up upon coarse-graining are illustrated through simple examples from crystal growth, defect dynamics, adsorption–desorption, surface diffusion, and phase transitions.

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An overview of spatial microscopic and accelerated kinetic Monte Carlo methods

Combustion characteristics and flame stability at the microscale: a CFD study of premixed methane/air mixtures

Palladium supported MCM-41 molecular sieves with Si/Pd (molar) ratios of 400, 200, 100 and 50 were synthesized by hydrothermal method. All catalysts characterized by various analytical and spectroscopic techniques, viz, XRD, N2 sorption, TEM, DRUV-VIS, Raman. XRD at low angle and high angle studies suggest that the substitution of palladium and presence of palladium oxide phase in the silicate tetrahedral framework structure of MCM-41. TEM investigations confirm the highly ordered cubic structure with irregular distribution of palladium nanoparticles on surface PdMCM-41. DRUV-VIS and Raman spectra studies indicate the presence of palladium oxide moieties in all PdMCM-41 catalysts. The effect of Si/Pd molar ratio, particle size and reusability with respect to reactor temperature on the catalytic activity of PdMCM-41 catalyst was examined. Comparative study of all these palladium substituted catalysts shows that PdMCM-41(50) catalyst having higher palladium contents shows higher activity at lower temperatures as compared with other PdMCM-41(Si/Pd = 100, 200, 400) catalysts.

Palldium supported mcm-41 mesoporous molecular sieves: synthesis, characterization and catalytic test for the reduction of no by co

Superior catalytic performance of Zr-incorporated MnCu/SBA-15 catalyst for low-temperature NH3-SCR of NO: Effect of support

Underground coal gasification is an in situ coal utilization technique that has immense potential as a future clean coal technology. UCG possesses a number of advantages including the ability to use deep and unmineable coals. The most important component of UCG is the underground “cavity”—which serves as a chemical reactor with rich interplay of kinetics and transport. Field and laboratory-scale experiments have revealed several interesting features of the UCG cavity. Modeling studies on the UCG cavity involve fundamental models and CFD simulations. In this chapter, we will discuss various experiments and models of UCG cavities, with a focus on the effects of reaction chemistry and thermomechanical spalling on cavity evolution.

Cavity Models for Underground Coal Gasification

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Preeti Aghalayam

Papers

Palldium supported mcm-41 mesoporous molecular sieves: synthesis, characterization and catalytic test for the reduction of no by co

Superior catalytic performance of Zr-incorporated MnCu/SBA-15 catalyst for low-temperature NH3-SCR of NO: Effect of support

Cavity Models for Underground Coal Gasification

Supercritical injection, combustion and acoustic interactions in a semi-cryogenic liquid propellant rocket engine injector