31 research outputs found
Generalized Gravi-Electromagnetism
A self consistant and manifestly covariant theory for the dynamics of four
charges (masses) (namely electric, magnetic, gravitational, Heavisidian) has
been developed in simple, compact and consistent manner. Starting with an
invariant Lagrangian density and its quaternionic representation, we have
obtained the consistent field equation for the dynamics of four charges. It has
been shown that the present reformulation reproduces the dynamics of individual
charges (masses) in the absence of other charge (masses) as well as the
generalized theory of dyons (gravito - dyons) in the absence gravito - dyons
(dyons). key words: dyons, gravito - dyons, quaternion PACS NO: 14.80H
Characterization and catalytic activity of Ni-W/SiO<sub>2</sub>-Al<sub>2</sub>O<sub>3</sub> hydrocracking catalysts
169-175Characterization of Ni-W SiO2-Al2O3
catalysts was carried out by microcalorimetry, TPR and oxygen chemisorption.
The effect of incorporation of individual metals and their sequence of addition
to the support on the properties and catalytic activity for cyclohexene hydrogenation
and cumene cracking was investigated. While the addition of nickel to SiO2-Al2O3
has little effect on the acidity, tungsten has generated some new strong acid sites,
which do not seem to have beneficial effect for cumene cracking. Low temperature
TPR peak in the bimetallic catalysts falls around 760 K due to Ni-W species while
the high temperature peak around 1115-1223K corresponds to W species. W/SiO2-Al2O3
has a lower oxygen chemisorptions than its nickel counterpart but has a higher
hydrogenation rate. Tungsten is the active metal for hydrogenation. W-Ni/SiO2-Al2O3
catalyst has better hydrogenation and cracking activity
Characterization and catalytic activity of Ni-W/Si02-Al203 hydrocracking catalysts
Characterization of Ni-W SiOrAI203 catalysts was carried out by microcalorimetry, TPR and oxygen chemisorption.
The effect of incorporation of individual metals and their sequence of addition to the support on the properties and catalytic
activity for cyclohexene hydrogenation and cumene cracking was investigated. While the addition of nickel to Si02-AI203
has little effect on the acidity, tungsten has generated some new strong acid sites, which do not seem to have beneficial effect
for cumene cracking. Low temperature TPR peak in the bimetallic catalysts falls around 760 K due to Ni-W species
while the high temperature peak around 1115-1223K corresponds to W species. W/SiOrAI203 has a lower oxygen chemisorption
than its nickel counteqJart but has a higher hydrogenation rate. Tungsten is the active metal for hydrogenation. W-Ni/SiO2-Al203
catalyst has better hydrogenation and cracking activity
Control of mesoporosity in alumina
157-161The textural properties of the alumina
carrier play a major role in governing the performance of alumina based heterogeneous
catalysts. The regulation of the pore size distribution in the support is of paramount
importance in the development of a promising catalyst. The role of peptising agent,
combustible additives and binder in regulating the mesoporosity has been investigated
using high pressure mercury porosimetry. Control of pore size in 18-50Å radii
range can be achieved by peptising alumina monohydrate (boehmite) by 1.5% nitric
acid. Additives like polyvinyl alcohol and polyethylene glycol have broadened the
mesopores while carbon black has drastically increased pores in 50-100Å range. Addition
of 10% calcined alumina as binder has been found suitable to maintain pores
<50 Å radii