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.