Daniel G. Löffler

Kinetics of ammonia decomposition on polycrystalline tungsten

Abstract The rates of ammonia decomposition on polycrystalline tungsten wires between 900 and 2200K and at pressures between 20 and 770 Torr are measured. All data can be fit accurately at all temperatures and pressures by a Langmuir-Hinshelwood unimolecular reaction rate expression. Comparison with previous results suggests that this rate expression can be used to approximate reaction rates at pressures down to 10 −3 Torr. Thus a single rate expression describes the reaction over a range larger than 10 5 in reactant pressure.

Kinetics of water desorption from pelletized 4A and 5A zeolites

Abstract Kinetic parameters (orders of desorption, pre-exponential factors and activation energies) are determined for the desorption of water from pelletized Linde 4A and 5A zeolites using temperature programmed desorption. The values of the parameters agree well with those in the literature.

Interactions of methane with tungsten, molybdenum, and platinum

Reaction rates are reported for decomposition of methane on tungsten, molybdenum, and platinum wires. Diffusion coefficients for carbon in W and Mo were measured by variation with reaction time of the electrical conductivity. Max temperature of the reaction was limited by the melting point of Pt or the breaking of brittle Mo and W carburized wires. For W wires, a single reaction rate expression describes the reaction between 10/sup -4/ and 770 torr. Measured reaction rates on Pt and Mo are similar, although Pt appears to be a better catalyst in the lower temperature range investigated. 11 references, 5 figures.

Ammonia decomposition on Ir and Pt wires

The rates of ammonia decomposition on polycrystalline Ir and Pd wires were measured at temperatures between 900 and 2000 K and at pressures between 50 and 770 Torr. Rates on Ir were fitted with a Langmuir-Hinshelwood unimolecular reaction rate expression. Rates on Pd could not be fitted with a rate expression, although activation energies were obtained.AbstractСкорость разложения аммония на провоке поликристаллических Ir и Pd была измерена при температурах 900–2000 К и давлениях 50–770 торр. Скорости на Ir подчиняются выражению для мономолекулярной реакции типа Лангмюра-Хин-шельвуда. Скорости на Pd не подчиняются этому выражению. Определены их энергии активации.

Ammonia decomposition on polycrystalline Pt at pressures between 1.3 and 93 kPa

The kinetics of ammonia decomposition on polycrystalline Pt at temperatures between 600 and 1700 K and at pressures between 1.3 and 93 kPa were measured and correlated with a Langmuir-Hinshelwood unimolecular reaction rate expression. This rate expression had previously been shown to fit data in the same temperature range for pressures between 2 and 1400 Pa.AbstractИзмерена кинетика разложения аммиака на поликристаллической Pt в интервале температур 600–1700 К и при давлениях от 1,3 до 93 кПа, которая подчиняется уравнению Пангмюра-Хиншельвуда для скорости мономолекулярной реакции. Это уравнение скорости, как уже ранее установлено, соответствует данным в том же интервале температур, но для давлений от 2 до 1400 Па.

Kinetics of 1-hexene dimerization catalyzed by a liquid-phase nickel complex

Reaction rates and activation energies for the oligomerization of 1-hexene catalyzed by a nickel complex of the formula Ni(F3COO)(C7H15COO) have been measured at temperatures varying between 0 and 20°C. Diethyl aluminium chloride was used as cocatalyst.

Kinetics of n-heptane desorption from pelletized zeolite 5A

Abstract Kinetic parameters for the desorption of normal heptane from pelletized zeolite 5A have been obtained by temperature-programmed desorption. The desorption spectra present two main peaks, which can be fitted quantitatively assuming four different binding states and neglecting readsorption.

Kinetics of ammonia decomposition of polycrystalline rhodium at pressures between 0.013 and 103 kPa

The rates of ammonia decomposition on polycrystalline Rh wires between 600 and 1800 K and at pressures between 13.3 Pa and 103 kPa were measured and fitted with a Langmuir-Hinshelwood unimolecular reaction rate expression. At high temperatures and pressures the reaction seems to be mass transfer controlled.AbstractИзмерена скорость разложения аммония на поликристаллической проволоке Rh в интервале температур 600–1800 K и при давлениях 13,3 Па−103 кПа. Она описывается уравиением скорости мономолекулярной реакции, типа Лаигмюра-Хиншельвуда. При высоких температурах и давлениях скорость реакции лимитируется переносом массы.

Effect of traces of water vapor on the rate of ammonia decomposition on polycrystalline platinum

The influence of small (lower than 0.02) molar fractions of water on the rate of ammonia decomposition on platinum wires was studied for ammonia pressures varying between 6.7 and 93.3 kPa and temperatures between 800 and 1700 K. The presence of water strongly inhibited the rate of reaction in all experiments.AbstractВлияние малых (ниже 0,02) молярных фракций воды на скорость разложения аммиака на платиновой проволоке исследовали при давлениях аммиака, изменяющихся в интервале от 6,7 до 93,3 кПа, и температурах от 800 до 1700 K. Присутствие воды сильно ингибирует скорость реакции во всех экспериментах.

Formic acid decomposition on polycrystalline tungsten

The rates of HCOOH decomposition on polycrystalline tungsten are examined over a wide range of catalyst temperatures (600<T<1800 K) at pressures between 0.1 and 100 Torr. Low pressure (p≤3 Torr) data can be fitted by a Langmuir-Hinshelwood unimolecular rate expression; at higher pressures the reaction becomes mass transfer controlled.AbstractСкорость распада HCOOH на поликристаллическом вольфраме проверялась в широком интервале температур катализатора (600<T<1800 К) для давлений между 0,1 и 100 торр. Данные для низкого давления (p≤3 торр) могут быть описаны уравнением Лангмюра-Хиншельвуда для скорости мономолекулярной реакции; при более высоких давлениях реакция становится контролируемой передачей массы.