Methane oxidation at high pressures and intermediate temperatures was investigated in a laminar flow reactor and in a rapid compression machine (RCM). The flow-reactor experiments were conducted at 700-900 K and 100 bar for fuel-air equivalence ratios (Φ) ranging from 0.06 to 19.7, all highly diluted in nitrogen. It was found that under the investigated conditions, the onset temperature for methane oxidation ranged from 723 K under reducing conditions to 750 K under stoichiometric and oxidizing conditions. The RCM experiments were carried out at pressures of 15-80 bar and temperatures of 800-1250 K under stoichiometric and fuel-lean (Φ=0.5) conditions. Ignition delays, in the range of 1-100 ms, decreased monotonically with increasing pressure and temperature.

a b s t r a c tAmmonia oxidation experiments were conducted at high pressure (30 bar and 100 bar) under oxidizing and stoichiometric conditions, respectively, and temperatures ranging from 450 to 925 K. The oxidation of ammonia was slow under stoichiometric conditions in the temperature range investigated. Under oxidizing conditions the onset temperature for reaction was 850-875 K at 30 bar, while at 100 bar it was about 800 K, with complete consumption of NH 3 at 875 K. The products of reaction were N 2 and N 2 O, while NO and NO 2 concentrations were below the detection limit even under oxidizing conditions. The data were interpreted in terms of a detailed chemical kinetic model.

Unprecedented insight into the carbonylation of dimethyl ether over Mordenite is provided through the identification of ketene (CH2CO) as a reaction intermediate. The formation of ketene is predicted by detailed DFT calculations and verified experimentally by the observation of doubly deuterated acetic acid (CH2DCOOD), when D2O is introduced in the feed during the carbonylation reaction.

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Dimethyl ether carbonylation to methyl acetate over mordenite was studied theoretically with density functional theory calculations and experimentally in a fixed bed flow reactor. A new reaction path to methyl acetate entirely in the 8 membered ring was discovered.

Ethane oxidation at intermediate temperatures and high pressures has been investigated in both a laminar flow reactor and a rapid compression machine (RCM). The flow-reactor measurements at 600-900 K and 20-100 bar showed an onset temperature for oxidation of ethane between 700 K and 825 K, depending on pressure, stoichiometry, and residence time. Measured ignition delay times in the RCM at pressures of 10-80 bar and temperatures of 900-1025 K decreased with increasing pressure and/or temperature. A detailed chemical kinetic model was developed with particular attention to the peroxide chemistry. Rate constants for reactions on the C 2 H 5 O 2 potential energy surface were adopted from the recent theoretical work of Klippenstein. In the present work, the internal H-abstraction in CH 3 CH 2 OO to form CH 2 CH 2 OOH was treated in detail. Modeling predictions were in good agreement with data from the present work as well as results at elevated pressure from literature. The experimental results and the modeling predictions do not support occurrence of NTC behavior in ethane oxidation. Even at the high-pressure conditions of the present work where the C 2 H 5 + O 2 reaction yields ethylperoxyl rather than C 2 H 4 + HO 2 , the chain branching sequence CH 3 CH 2 OO −→ CH 2 CH 2 OOH +O 2 −→ OOCH 2 CH 2 OOH → branching is not competitive, because the internal H-atom transfer in CH 3 CH 2 OO to CH 2 CH 2 OOH is too slow compared to thermal dissociation to C 2 H 4 and HO 2 .

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