Chemisorb 2720/2750

Micromeritics
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.

Features

The ChemiSorb 2720
V ersatility in an Inexpensive Chemisorption System

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.

  • Dual ports, one for analysis and one for sample preparation.
  • Built-in sample cooling fan, four carrier gas inlets, and one prep gas inlet.
  • The basic instrument can measure percent dispersion, active metal area, crystallite size, and quantify acid and base sites using pulse chemisorption. Physisorption tests include BET and Langmuir surface area,and total pore volume.
  • An optional access fitting allows the ChemiSorb to utilize a mass spectrometer or other external detector for identification of desorbed species or reaction products.

The ChemiSorb 2750
Higher Precision and Versatility

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.

Higher precision, repeatability, and reproducibility are provided by the incorporation of an injector loop valve in addition to the injection septum. The loops are easily exchanged to provide different injection volumes. Electrically activated inlet valves allow the use of gases containing H2, CO,O2, N2O, NH3, liquid vapor sources, or other adsorptives. Three built-in prep gas inlets and four carrier gas inlets allow for a variety of experiments without having to disconnect, reconnect, and purge gas lines.

 

Added Capability – Optional ChemiSoft TPx System

  • Optional ChemiSoft TPx System (temperature-programmed controller and software) expands the capabilities of the ChemiSorb 2720 and 2750 to include temperature-programmed reactions, data archiving, and advanced data reduction and reporting options
  • Expanded physisorption capability includes multipoint BET surface area.

* Dual Function Analysis/Preparation
** One dedicated controller for preparation port and one dedicated controller for the analysis port

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  1. Feature Comparison
    ChemiSorb Features

    2720

    2750

    · Analysis Ports

    1

    2*

    · Preparation Port

    1

    *

    · Injection Septum

    Yes

    Yes

    · Injection Loop

    Yes

    · Sample Reactor

    Quartz

    Quartz

    Gas Inlets
    · Carrier

    4

    4

    · Preparation

    1

    3

    · Loop

    1

    Temperature Control
    · Integrated

    2**

    2

    · Max Temperature

    400 °C

    400 °C

    · With TPx Option

    1100 °C

    1100 °C

    · Fan-assisted Cooling

    1

    2

    Standard Analysis
    · Pulse Chemisorption

    Yes

    Yes

    · Physisorption

    Yes

    Yes

    ChemiSoft TPx Analyses
    · TPR

    Yes

    Yes

    · TPD

    Yes

    Yes

    · TPO

    Yes

    Yes

    · Pulse Chemisorption

    Yes

    Yes

    · Physisorption

    Yes

    Yes

    · Loop Calibration

    Yes

    ChemiSoft TPx Reports
    · % Metal Dispersion

    Yes

    Yes

    · Metal Surface Area

    Yes

    Yes

    · Average · Crystallite Size

    Yes

    Yes

    · First Order Kinetics

    Yes

    Yes

    · Single-point Surface Area

    Yes

    Yes

    · BET Mulitipoint Surface Area

    Yes

    Yes

    · Langmuir Surface Area

    Yes

    Yes

    · Total Pore Volume

    Yes

    Yes

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Applications

Catalysts
The active surface area and porous tructure of catalysts have a great influence on production rates. Limiting the pore size allows only molecules of desired sizes to enter and leave; creating a selective catalyst that will produce primarily the desired product. Chemisorption experiments are valuable for the selection of catalysts for a particular purpose, qualification of catalyst vendors, and the testing of catalyst performance over time to establish when the catalyst should be reactivated or replaced.

Fuel Cells
Platinum-based catalysts including Pt/C, PtRu/C, and PtRuIr/C are often characterized by temperature-programmed reduction to determine the number of oxide phases and pulse chemisorption to calculate:

  • Metal surface area
  • Metal dispersion
  • Average crystallite size

Partial Oxidation
Manganese, cobalt, bismuth, iron, copper, and silver catalysts used for the gas-phase oxidation of ammonia, methane, ethylene, and propylene are characterized using:

  • Temperature-programmed oxidation
  • Temperature-programmed desorption
  • Heat of desorption of oxygen
  • Heat of dissociation of oxygen

Catalytic Cracking
Acid catalysts such as zeolites are used to convert large hydrocarbons to gasoline and diesel fuel. The characterization of these materials includes:

  • Ammonia chemisorption
  • Temperature-programmed desorption of ammonia
  • Temperature-programmed decomposition of alkyl amines
  • Temperature-programmed desorption of aromatic amines

Catalytic Reforming
Catalysts containing platinum, rhenium, tin, etc. on silica, alumina, or silica-alumina are used for the production of hydrogen, aromatics, and olefins. These catalysts are commonly characterized to determine:

  • Metal surface area
  • Metal dispersion
  • Average crystallite size

Isomerization
Catalysts such as small-pore zeolites (mordenite and ZSM-5) containing noble metals (typically platinum) are used to convert linear paraffins to branched paraffins. This increases the octane number and value for blending gasoline and improves the low temperature flow properties of oil. The characterization of these materials includes:

  • Temperature-programmed reduction
  • Pulse chemisorption

Hydrocracking, Hydrodesulfurization, and Hydrodenitrogenation
Hydrocracking catalysts typically composed of metal sulfides (nickel, tungsten, cobalt, and molybdenum) are used for processing feeds containing polycyclic aromatics that are not suitable for typical catalytic cracking processes. Hydrodesulphurization and hydrodenitrogenation are used for removing sulfur and nitrogen respectively from petroleum feeds. The characterization of these materials includes:

  • Temperature-programmed reduction
  • Oxygen pulse chemisorption

Fischer-Tropsch Synthesis
Cobalt, iron, etc. based catalysts are used to convert syngas (carbon monoxide and hydrogen) to hydrocarbons larger than methane. These hydrocarbons are rich in hydrogen and do not contain sulfur or nitrogen. The characterization of these materials includes:

  • Temperature-programmed desorption
  • Pulse chemisorption
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