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The kinetics of ethylene and propylene oxidation over Rh and Ru supported on low area α-alumina were studied and found similar to those reported earlier for the same metals supported on high area silica. The selectivities for product formation were also analogous. The most selective reaction was oxidation of C 3 H 6 over Rh at 200 °, where substantial amounts of acrolein and acetone were formed. Substitution of deuterium for hydrogen in the olefin methyl-group reduced the rates of these reactions significantly, showing that abstraction of H from this position was involved in the rate-determining steps. The acetones formed from labeled propylenes contained deuterium in all possible positions, but exchange into the product acroleins was minor and confined mainly to the 2-position. The acrolein from CD 3 CHCH 2 and CH 3 CHCD 2 contained nearly equal amounts of the d 1 and d 2 species, but the unreacted propylene was unisomerized. The absolute values for the deuterium contents showed that the bulk of the acrolein was formed via a symmetric allyl-type intermediate, but that up to 26% of the reaction proceeded with the direct conversion of the methyl group of the olefin into the aldehyde group. The data also showed that the isotope effect for the removal of the second H (or D) from the olefin is minimal. Possible mechanisms to explain these findings are presented.

The infrared spectra of the OH groups of a hydrogen-Y-zeolite have been recorded in the presence of C2H4 at pressures up to 1 atm and in the temperature range 25 to 150 °C. From these data, the heat of formation of hydrogen-bonded C2H4 was estimated to be about 9 kcal mole−1 for interaction with the 3648 cm−1 groups. Isotopic exchange between C2D4 and the two principal types of OH groups was studied at temperatures between 200 and 350 °; both exchanged at about the same rate. Equilibration of C2D4 and C2H4 proceeded via exchange with the surface OH groups. C 2 D 4 OH exchange took place 1.2 times faster than C 2 H 4 OD exchange over zeolite samples pretreated in equivalent ways. The kinetics deviated slightly from a first order dependence on the distance from equilibrium. The apparent first order rate constants reached an apparent maximum for pretreatment at 290 °C. The apparent activation energy for exchange was 16 kcal mole−1 for samples pretreated at 290 °C and 19 kcal mole−1 for those heated at 475 °C in O2 and rehydrated at 350 °C. In both instances, the reaction was first order in C2D4 pressure.

The catalytic oxidation of C2H4 and C3H6 was studied over silica-supported Pt, Pd, Ir, Ru, and Rh. The specific activities fell in the order listed and correlated with the percentage d-character of the metal and fairly well with its atomic radius. The partial oxidation products were characterized. Acetaldehyde and acetic acid were produced from C2H4 in all cases, but only with Pd and Ir were the quantities significant. Products from C3H6 were more varied. C3 products in substantial amounts were formed over Rh, Ru, and Pd, the selectivity decreasing in the order given. Somewhat smaller amounts of C2 products were also formed over these catalysts. The principal product over Ir was acetic acid; the most active catalyst, Pt, was relatively unselective. Three different types of pressure dependencies were found: the rate of total oxidation decreased with olefin pressure and increased with oxygen pressure over Pt and Pd; the rate increased with olefin pressure and was inhibited by oxygen over Rh and Ir; and the rate increased with oxygen pressure, but was nearly independent of olefin pressure over Ru. Activation energies varied from 16 to 29 kcal/mole and tended to correlate inversely with the catalytic activity. The order of activity depended upon the ability of the metal to activate O2.

The gross kinetics for the oxidation of ethylene were determined over Pd and PdAu alloys in a steady-state flow reactor and in a recirculating reactor in which the products were stripped with each pass. The partial oxidation products over Pd included acetic acid, acetic anhydride, acetaldehyde, and (a trace) ethylene oxide. Initial selectivity for partial oxidation varied between 25 and 45%, depending upon reaction conditions; steady-state values fell in the range, 6–25%. Both the total rate and selectivity increased with O 2 pressure. The rates of both total and partial oxidation passed through maxima near 5 Torr with varying C 2 H 4 pressure, changing from first-order at lower pressures to negative-order at higher. The apparent activation energy, based on initial rate data was 20 ± 2 kcal/mole for both complete and partial oxidation, but was 30 ± 2 kcal/mole for steady-state measurements. The difference may reflect effects of poisoning by products. When small amounts of acetaldehyde- 14 C were added to the reaction, 80% of the radioactivity was recovered in the acetic acid and 10% as CO 2 . Added ethylene oxide- 14 C was recovered unreacted. The C 2 H 4 reacted about 1.4 times faster than C 2 D 4 . Scrambling in the unreacted ethylenes during oxidation of equimolar mixtures was minimal at low ethylene pressures. No 16 O 18 O was found when mixtures of 16 O 2 and 18 O 2 were used to oxidize ethylene, but the isotopic distribution in the product CO 2 was near equilibrium. The PdAu alloys were much less active than pure Pd and much more active than Au. The selectivity, however, went through a maximum (~50%) near 20% Pd. A similar maximum was found for fast O 2 chemisorption.

The infrared spectrum of ammonia adsorbed on porous glass at 20 °C and 150 °C has been studied in the region 1450–4000 cm−1. No absorption band due to the asymmetric bending mode of ammonia was observed but in the NH stretching region, bands occurred at 3280 cm−1, 3320 cm−1, 3365 cm−1, and 3400 cm−1. The bands at 3320 cm−1 and 3400 cm−1 were easily removed by evacuation and are due to ammonia molecules hydrogen bonded through the nitrogen atom to surface hydroxyl groups. The bands at 3280 cm−1 and 3365 cm−1 were not removed by evacuation even at 150 °C and are due to ammonia molecules held to surface Lewis acid sites by the nitrogen lone-pair electrons. The site for this adsorption is not a surface hydroxyl group. These results are further evidence for the existence of the two adsorption sites proposed by Folman and Yates. Deuteration of the surface OH groups was easily accomplished with D2O vapor at 300 °C and the rate of hydrogen exchange between adsorbed ammonia molecules and surface OD groups was found to be rapid.

It has been shown previously that two types of adsorption sites exist on the surface of porous silica glass (Corning code no. 7930) for the adsorption of polar molecules, such as ammonia. One site is the surface hydroxyl group which forms a hydrogen bond to the adsorbate molecule. The second type of site is provided by traces of foreign oxides on the glass surface.In the present study, the infrared spectrum of ammonia adsorbed on the silica glass has been compared with that of ammonia adsorbed on samples prepared by adding B2O3, ZrO2, and Al2O3 to a pure silica powder. This comparison suggests that surface boron atoms (a Lewis acid) are the adsorption sites for ammonia on the porous silica glass. An additional type of site (a Bronsted acid or a different type of Lewis acid site, such as aluminium atoms) may exist in small concentrations on the glass and be responsible for isomerization and polymerization reactions with olefins.

Fluorination of porous silica glass led to an increase in the number of adsorption sites which coordinate ammonia. Evacuation of fluorinated and unfluorinated glass at temperatures of approximately 650 °C for 2–3 hr produced a surface which coordinated ammonia molecules, with little evidence of their dissociation. Other studies have shown that after evacuation under more severe conditions, silica glass adsorbed ammonia with much dissociation and with the production of primary and secondary amine radicals.

The ν2 symmetrical deformation vibration for ammonia adsorbed on silica cannot be observed directly, owing to strong absorption arising from the adsorbent. It is possible, however, to calculate a value for this vibrational frequency based on combination bands for the adsorbed ammonia, which occur in regions remote from strong absorption by the silica. The frequency of the ν2 mode reflects the strength of bonding in both the adsorbed state and in metal–ammine complexes.

The reactions of ethylene, propylene, 1-butene, cis-2-butene, trans-2-butene, iso-butene and the two 2-pentenes were compared over supported Ir catalysts. The rates of total oxidation decreased in the order given, while the corresponding apparent activation energies increased. With ethylene, rate maxima appeared on varying the pressure of either reactant; with propylene and 1-butene, maxima were found with oxygen only; with the other olefins, the rates increased with olefin pressure and were inhibited by oxygen over the entire range studied. About 40% of all the olefin oxidized became partial oxidation products. The most important of these were acetic acid from ethylene, propylene, the 2-butenes and the 2-pentenes, and propionic acid and acetone from 1-butene and isobutene, respectively. Smaller amounts of unsaturated aldehydes, diones and other ketones and acids were also detected. The acetic acid formed from propylene-1-14C was not radioactive. A large kinetic isotope effect was found for the total oxidation of propylene labeled with deuterium in the methyl group. Possible mechanisms are discussed.