Topics Covered
Background
The ChemiSorb 2720
Higher
Precision and Versatility - The ChemiSorb 2750
Optional ChemiSoft
TPx System
ChemiSoft TPx
Software
Background
The ChemiSorb 2720 and ChemiSorb 2750 can be equipped to perform chemical and
physical adsorption tests that are central to the development, testing, and
production of catalysts. They employ the dynamic (flowing gas) technique of
analysis by which the quantity of gas taken up by the sample or released from
the sample surface is monitored by a Thermal Conductivity Detector (TCD). Data
obtained by the instruments can be used to calculate key parameters for catalyst
characterization: metal dispersion, active surface area, BET surface area,
average crystallite size, surface acidity or basicity, and activation energy via
first order kinetic models.
The ChemiSorb 2720
This basic system without the TPx option makes chemisorption
and physisorption analyses affordable to even the most modestly funded
laboratories. The instrument rapidly and accurately performs pulse chemisorption
studies and surface area analyses. The ChemiSorb 2720 features one port dedicated to performing the
sorption analysis and a second port designed for sample preparation. It also
features a built-in cooling fan for the sample port, four carrier gas inlets,
one prep gas inlet, and the optional capability to accommodate a mass
spectrometer or other external detector attached at the exhaust port. In
addition to chemisorption experiments that include determining the percent metal
dispersion, active metal area, crystallite size, and quantifying acid and base
sites, a range of physisorption experiments including BET surface area, Langmuir
surface area, and total pore volume can also be conducted. Hands-on calibration
and dosing procedures make it an excellent teaching tool for gas-solid surface
interaction studies.
The basic instrument (without the ChemiSoft TPx option) provides two ways to collect data: 1)
via a front panel meter that may be calibrated to display gas volumes adsorbed
onto or desorbed from a sample, and 2) by a chart recorder monitoring the analog
output from the thermal conductivity detector.
Higher Precision and Versatility - The ChemiSorb 2750
The ChemiSorb 2750 (built upon the same design elements as the Chemisorb 2720) has been further enhanced with the addition of
an injection loop for pulsing active gases on the catalyst and features an
enhanced dual-port design that allows in-situ preparation and analysis of two
samples. Its dual-function sample ports have the capability to be used as either
an analysis port or a degas port, eliminating the need to move the sample. This
requires less effort and reduces the chances of contaminating an activated
sample from exposure to stray gases.
Performing different types of analyses is also easier. In
addition to the four carrier gas inlets and three preparation gas inlets, a
dedicated gas inlet for the pulse chemisorption gas has been added. Thus the
increased number of ports provides a rapid method for gas change overs without
the need to manually disconnect, reconnect, and purge gas lines; this further
minimizes the risk of contamination and improves the ease of operation.
Optional ChemiSoft TPx System
When the optional programmable furnace system and
accompanying ChemiSoft TPx software are added, another category of chemical
adsorption testing can be performed - Temperature-Programmed reactions reduction
(TPR), oxidation (TPO), and desorption (TPD).
Temperature control is provided by a furnace that operates
from ambient (20 °C) to 1100 °C, and is able to produce temperature ramps of up
to 50 °C/min within the 20 to 500 °C range, 30 °C/min within the 500 to 750 °C
range, and up to 10 °C/min in the 750 to 1100 °C range. The furnace controller
can be programmed to provide multiple ramps and soak times.
ChemiSoft TPx Software
Included in the Temperature-Programmed reactions option is
Micromeritics’ ChemiSoft software that can be used to simplify chemisorption
and physisorption as well as temperature-programmed analyses. The software
tracks the detector (TCD) output and plots the signal as a function of time
and/or temperature. Using these data the instrument produces a variety of
user-defined reports. Advanced peak integration capabilities assure reliable
results.
With ChemiSoft, you can create and store standard sets of analysis
conditions for guiding frequently performed analyses. Analysis and prep
conditions also are reported to provide a record of the environment under which
the reported data were collected; this also assures faithful repeating of an
experiment if required. Cut-and-paste and data export features simplify moving
data to reports or incorporating chemisorption data with data from other
analytical techniques.
Source: Micromeritics
For more information on this source please visit Micromeritics
Instrument Corp.