Stereochemistry of Certain Catalytic Reactions of Cyclic Hydrocarbons in the Presence of Group VIII Noble Metals

Abstract

We have studied the off-axis light transmission properties of the bright state in Pi-cell (-cell) devices as a function of the white state director configuration that is determined by the applied white state voltage and the pretilt angle of the device. Results show that below certain values of the voltage or pretilt angle, the off-axis light transmission properties are insensitive to these parameters and can be described by a previously considered simple model. However, above a critical pretilt angle or white state voltage, the light transmittance is a much stronger function of the incident angle of light. To understand the facts, we develop a model that explains this result and provides a description of the basic issues affecting the optics of these types of devices.

Mechanistic Pathways for Methylcyclohexane Hydrogenolysis over Supported Ir Catalysts

“…In the third group, the RDS is assumed to be one of the C–H bond reformation steps subsequent to the C–C bond cleavage. In the last group, called the “associative” or the “multiplet” mechanism, , the C–C bond of a flat-lying physisorbed cyclic molecule is cleaved upon the attack of a H atom coadsorbed on the surface. Variants exist within each group of mechanisms, as will be discussed.…”

“…The foregoing analyses are based on “dissociative” mechanisms that involve C–H bond rupture steps preceding scission of the C–C bond. In the “multiplet” mechanism, the cyclic hydrocarbon is physically (flat-lying and nondissociated) adsorbed over metal surfaces . The ring is cleaved upon the attack of a coadsorbed H atom.…”

“…In the "multiplet" mechanism, the cyclic hydrocarbon is physically (flat-lying and nondissociated) adsorbed over metal surfaces. 30 The ring is cleaved upon the attack of a coadsorbed H atom. This "associative" mechanism, however, is not able to describe the observed kinetics, in terms of fractional orders in MCH and negative orders in H 2 .…”

Dehydrogenation of polycyclic hydroaromatic compounds

“…zation (e.g., toluene to stilbene86), elimination of methyl groups on tertiary carbon atoms (e.g., 1,1,6-trimethyltetralin to 1,6-dimethylnaphthalene91), and condensation (e.g., acenaphthene to dinaphthalenethiophene (15) and decacylene (16)92). All of these processes are consistent with free-radical intermediates.…”

Роль Структурно-Морфологического Состояния Поверхности Платины В Кинетических И Термодинамических Характеристиках Процесса Адсорбции Аниона Серина

“…Так, при увеличении степени дисперсности металла, когда средний размер частиц металла не превышает 3 nm, каталитическая активность Ru снижается, причем меняется природа продуктов реакции. Полагают, что подобный эффект прежде всего связан именно с различной геометрией адсорбции молекулы бензола [35][36][37][38]. Аналогичное влияние структурного состояния поверхности на природу продуктов отмечается и в работах, рассматривающих процесс дегидрирования циклогексана на поверхности Pt катализатора, представляющего собой грани монокристалла и дисперсный металл [39][40][41][42][43][44][45].…”