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.

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.

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.

ChemiSorb 2720 / 2750 Applications

ChemiSorb Theory and Design

The Analytical Technique

The ChemiSorb 2720 and 2750 both utilize the dynamic (flowing gas) technique of analysis. The quantity of gas adsorbed from the gas stream by the sample is monitored by a downstream thermal conductivity detector (TCD). The temperature and pressure at which adsorption/desorption occurs is either known or monitored. The instruments can be used to study physical or chemical adsorption. Preparation usually is accomplished by flowing either an inert or chemically active gas over the sample. After preparation, another gas is selected for analysis. Prep and carrier gases typically used to allow both physical and chemical adsorption experiments are He, Ar, N2, He/N2mixtures, H2, and O2, some serving as both prep and carrier.

Chemical Adsorption

Any of a number of reactive gases such as anhydrous NH3, CO2, CO, H2, N2O, O2, and H2S can be used to react with the active surface. A series of injections of a known quantity of reactive gas is injected into an inert gas stream that passes through the bed of catalysts. Downstream from the reactor is a detector, which determines the quantity of reactive gas that is removed from each injection. Chemisorption tests ideally are made with the sample at a temperature such that only chemisorption occurs. The active surface of the sample is saturated when the detector indicates that the total quantity of subsequent injections passes through the sample bed without any loss. The sum of the injected quantity minus the quantity of gas that passed without adsorption equals the quantity adsorbed.

Unlike physical adsorption, the injected gas chemically adsorbs only on the active surface and not on the support. Thus, the number of gas molecules required to cover the active surface area, once determined, leads directly to the active surface area. Applying the stoichiometry factor for metal reaction yields the number of accessible atoms of active metal. Furthermore, using the total quantity of active metal per gram of catalyst material (determined from the manufacturing formula) leads to the determination of the percent dispersion of active metal. Using the information gathered plus the density of the metal, the size of the metal crystallite can be estimated if it is assumed that these particles have uniform geometry of known volume-to-area ratio.

Physical Adsorption

The surface area of granulated and powdered solids or porous materials is measured by determining the quantity of a gas required to form a monomolecular layer on a sample. Physical adsorption tests typically are performed at or near the boiling point of the adsorbate gas; N2 being most common with a liquid N2 bath being used to maintain the analysis temperature. Under these conditions, a nitrogen and helium mixture of 30 volume percent nitrogen achieves the partial pressure condition most favorable for the formation of a monolayer of adsorbed nitrogen at atmospheric pressure. Under such specific conditions, the area covered by each gas molecule is known within relatively narrow limits. The area of the sample is thus calculable directly from the number of adsorbed molecules, which is derived from the gas quantity at the prescribed conditions, and the area occupied by each. Additionally, atmospheric pressure and ice water temperature may establish appropriate conditions for an n-butane and helium mixture. Other gases at other conditions are also usable.

Chemisorption defined:

Chemical adsorption is an interaction much stronger than physical adsorption. In fact, the interaction is an actual chemical bond where electrons are shared between the gas and the solid surface. While physical adsorption takes place on all surfaces if temperature and pressure conditions are favorable, chemisorption only occurs on certain surfaces and only if these surfaces are clean. Chemisorption, unlike physisorption, ceases when the adsorbate can no longer make direct contact with the surface; it is therefore a single layer process.

ChemiSoft TPx Option

When the optional programmable furnace system and accompanying ChemiSoft TPxsoftware are added to the 2720 or the 2750, 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.

Temperature-programmed Chemisorption

Temperature-programmed chemisorption provides information about adsorption strength when a catalyst is at working condition or at an elevated temperature.TPD analyses determine the number, type,and strength of active sites available on the surface of a catalyst from measurement of the amount of gas desorbed at various temperatures. During a TPR analysis, a metaloxide is reacted with hydrogen to form a pure metal. TPR determines the number of reducible species present in the catalyst and reveals the temperature at which reduction occurs. TPO examines the extent to which a catalyst can be reoxidized and measures the degree of reduction of certain oxides.

ChemiSoft TPx Software

Included in the Temperature-Programmed Chemisorption option is Micromeritics’ChemiSoft software that can be used to simplify chemisorption and physisorption aswell as temperature-programmed analyses.The software tracks and records time, monitors and records the analytical temperature and detector output, creates and organizes data files, reduces collected data, and 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.

ChemiSoft TPx software can be set up to run independently of the instrument. This means that data files can be reviewed, calculation parameters changed, and reports generated on any computer anywhere, anytime.

Other functions of ChemiSoft

The ICCS incorporates:

To enable:

Wide Variety of Features and Benefits:

Chemical adsorption (chemisorption) analyses can provide much of the information needed to evaluate catalyst materials in the design and production phases, as well as after a period of use. The chemical adsorption isotherm reveals information about the active surface of a material have emerged as an indispensable companion to chemisorption isotherm analyses in many areas of industry.

Four internal temperature-controlled zones can be heated independently up to 150 °C. This prevents condensation in the flow path and allows studies to be performed with vapors.

Low internal plumbing volume assures high resolution, fast detector response, and reduces error.

Highly sensitive linear thermal conductivity detector (TCD) assures the calibration volume remains constant over the full range of peak amplitudes so the area under the peak is directly proportional to the volume of gas reacted.

Four high-precision mass flow controllers provide extremely accurate, programmable gas control.

Corrosion-resistant detector filaments are compatible with most destructive gases and reduce the likelihood of filament oxidation.

Clamshell furnace can heat the quartz sample reactor to 1100 °C. Any number of ramp rates and sequences facilitate customized experiments.

Four gas inlets each for the preparation, carrier, and loop gases permit four-gas sequential experiments, such as TPR/TPO cycles.

Hardware Advantages:

The AutoChem II features stainless-steel construction, fully automated flow and pressure control, an embedded microprocessor with real-time control, and an intuitive graphical user interface for reactor control. A temperature-controlled, stainless-steel flow path provides an inert and stable operating environment, and reduces the potential for condensation in the flow path.

The AutoChem II Technique:

During the TPR, a metal oxide reacts with hydrogen to form a pure metal. This reaction is referred to as a reduction; for example, TPR of a catalyst containing platinum. Argon, which has a very low relative thermal conductivity, is used as a component in the carrier gas.

It is blended in a fixed proportion with hydrogen, the reducing gas with a much higher thermal conductivity. Then the gas mixture flows through the analyzer, through the sample, and past the detector. When the hydrogen and argon gas blend begins flowing over the sample, a baseline reading is established by the detector.

This baseline is established at a low enough temperature so that no reduction of the sample occurs. The baseline level indicated by the detector is that of the thermal conductivity of the two gases in their fixed proportion.

The temperature is then raised and, when a critical temperature is reached, hydrogen atoms in the gas flow react with the sample, forming H2O molecules. The H2O molecules are removed from the gas stream using a cold trap.

As a result, the amount of hydrogen in the argon/hydrogen gas blend inside the analyzer decreases, and the proportion between the two gases shifts in the direction of argon, as does the mixture’s thermal conductivity.

Since argon has a lower thermal conductivity than hydrogen, the mixture’s thermal conductivity consequently decreases. The flowing gas removes heat from the filament more slowly, requiring less electricity to maintain a constant filament temperature.

AutoChem II 2920 Applications

Chemisorption:

Chemical adsorption is an interaction much stronger than physical adsorption. In fact, the interaction is an actual chemical bond where electrons are shared between the gas and the solid surface. While physical adsorption takes place on all surfaces if temperature and pressure conditions are favorable, chemisorption only occurs on certain surfaces and only if these surfaces are clean. Chemisorption, unlike physisorption, ceases when the adsorbate can no longer make direct contact with the surface; it is therefore a single layer process.

Catalyst

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

AutoChem II 2920 Software Features:

The easy-to-use AutoChem II software utilizes a Windows® interface that includes Wizards and applications to help plan, launch, and control the analysis.

You can collect, organize, archive and reduce raw data, and store standardized sample information and analysis conditions for easy access during later applications. Finished reports may be generated to screen, paper, or data transfer channels. Features include cut-and-paste graphics, scalable-and-editable graphs, and customizable reports.

Set up analysis protocol sequencing from any number of preprogrammed experiments or create a customized sequence. The user can easily select the pretreatment and analysis task and specify criteria such as temperature ramp rates, gas flow rates, and data measurement intervals in the desired sequence. Modifications may be made to the analysis protocol at any time, even during analysis.

The instrument schematic screen displays the instrument’s current operating status, including the availability of analysis and pretreatment gases and vapors, direction of the gas flow, and TCD reading.

Numerous plots can be overlaid for easy comparison of different samples or for comparison of different data reduction techniques applied to the same sample.

Exportable data tables provide for merging and comparing data from other sources in a single spreadsheet file.

Data Reduction and Reporting – Powerful Peak Editor:

Fully integrated, interactive peak editor package enables the user to evaluate results quickly and easily, edit peaks, and produce reports that reflect specific needs. Adjusting peak boundaries is a matter of simply pointing and clicking. The Peak Editor can also be used to deconvolute overlapping peaks. The peak deconvolution is a simple-to-use option on the peak space editor that allows the user to maximize the information.

Cirrus 3 Quadrupole Mass Spectrometer

Atmospheric Pressure Gas Monitoring

Building on proven Cirrus Quadrupole Mass Spectrometry technology, the Cirrus 3 combines state-of-the-art performance in compact benchtop and rack-mounted formats. With a heated capillary inlet and fast scan speed (250 points per second), gas compositions can be tracked over wide dynamic range (ppb to percentage levels) more reliably.

• Monitors multiple gas species from trace levels (ppb) to high abundance
• Fast response – 250 data points per second & capillary inlet heated up to 300°C
• Precise and stable user-defined temperature control with enhanced oven and capillary designs
• Detect gases up to 300 amu. High resolution options (1-100HP)
• Recipe-driven Process Eye Professional supports gas monitoring and quantitation applications
• Fast and Reproducible Data

Cirrus systems are based on Quadrupole Mass Spectrometry, widely acknowledged as a preferred platform technology for many atmospheric pressure gas analysis applications. The Cirrus 3 system, with its improved temperature control and compact design, provides high levels of performance and robustness in space-efficient and flexible configurations that are ideal for a wide range of analytical applications.

Precision engineered to provide fast and reproducible data, Cirrus 3 can accurately detect and quantify gases and gas mixtures, from one or more sampling locations with a single instrument. Gas composition can be monitored over a wide dynamic range, from percentage levels down to the sub ppm range.

Cirrus 3 is an ideal choice for atmospheric gas analysis whether you work in a research setting or a manufacturing environment. By combining Process Eye Professional software with MKS technical support, Cirrus can be integrated, optimized, and automated to your precise specifications. Ultimately, users across your organization realize greater benefits of the power of quadrupole mass spectrometry.

Quadrupole Analyzer

At the heart of every Cirrus 3 system is a precision-built quadrupole analyzer incorporating a closed ion source, a triple mass filter, and a dual (Faraday and Secondary Electron Multiplier) detector system. This analyzer configuration is selected to optimize sensitivity and longterm performance stability

The Cirrus 3 system enables the AutoChem II 2920 and AutoChem 2950 HP to function as multi-component microreactors. Cirrus 3 software includes Process Eye Professional which controls analyzer data collection and monitors real-time data and analyzer status.

A Recipe wizard helps create and configure analysis conditions. The Micromeritics/Cirrus interface software runs inside Process Eye Professional and is accessed via its own menu.

This interface enables the user to control the analyzer via recipes which can also be saved for future use. The interface allows the user to collect data automatically from the AutoChem, customize Peak Jump recipes, access standard operations, calibrate detectors, and scale the AutoChem sample thermocouple signal.

Data integration with AutoChem II 2920 and AutoChem 2950 HP

• MS data may be analyzed using the Micromeritics Peak Editor that allows signal deconvoution (peak fitting), signal integration, and smoothing.
• The AutoChem software may be used to create MS calibrations and convert raw signals to quantitative analyses.
• Data may be used directly in AutoChem characterization reports: dispersion, active area, kinetics, crystallite size.

Features and Benefits:

• Monitors multiple gas species over a wide dynamic range of composition at atmospheric pressure
• Compact, modular design for ease of serviceability and maintenance
• Direct Ethernet interface – fully network compatible
• Recipe driven Process Eye Professional software for automated operation and calibration
• Fast response, silica capillary inlet heated to 150° C

For sampling different gas conditions, inlet options available are:

• Stainless steel capillary
• Low flow capillaries
• Multi-stream inlets
• Automated variable pressure inlet

Applications

• Monitoring of trace contaminants in process gas
• Catalyst studies
• Fuel cell monitoring and development
• Heat treatment/furnace monitoring
• Membrane studies
• Glove box gas monitoring
• Lamp manufacture
• Gas supply monitoring (cylinder checks and special gas production)
• Freon detection and identification
• Environmental monitoring. Thermal analysis – TGA, DTA
• Fermentation process monitoring

• Programmable, two-station degas system allows physisorption sample preparation while running a chemisorption analysis
• Twelve gas inlets allow multiple probe gases to be investigated maximizing efficiency and range of applications
• Dedicated exhaust port for external detector connections
• High-temperature 1100 °C furnace rapidly ramps to temperature and provides excellent, stable temperature and control with quick cool downs In situ chemisorption sample reparation and activation provide a fully automated method that does not require user intervention
• In situ chemisorption sample preparation and activation provide a fully automated method that does not require user intervention
• Design permits quick and easy transition from chemisorption to physisorption analysis

Typical ASAP 2020 Plus Applications

Pharmaceuticals:

• Surface area and porosity play major roles in the purification, processing, blending, tableting, and packaging of pharmaceutical products as well as their useful shelf life, dissolution rate, and bio-availability.

Ceramics:

• Surface area and porosity affect the curing and bonding of greenware and influence strength, texture, appearance, and density of finished goods. The surface area of glazes and glass frits affects shrinkage, crazing, and crawling.

Adsorbents:

• Knowledge of surface area, total pore volume, and pore size distribution is important for quality control of industrial adsorbents and in the development of separation processes. Surface area and porosity characteristics affect the selectivity of an adsorbent.

Activated Carbons:

• Surface area and porosity must be optimized within narrow ranges to accomplish gasoline vapor recovery in automobiles, solvent recovery in painting operations, or pollution controls in wastewater management.

Carbon Black:

• The wear lifetime, traction, and performance of tires are related to the surface area of carbon blacks used in their production.

Fuel Cells:

• Fuel cell electrodes require high surface area with controlled porosity to produce optimum power density.

Catalysts:

• The active surface area and pore structure of catalysts influence production rates. Limiting the pore size allows only molecules of desired sizes to enter and exit, creating a selective catalyst that will produce primarily the desired product.

Paints and Coatings:

• The surface area of a pigment or filler influences the gloss, texture, color, color saturation, brightness,solids content, and film adhesion properties. The porosity of a print media coating is important in offset printing where it affects blistering, ink receptivity, and ink holdout.

Projectile Propellant:

• The burn rate of propellants is a function of surface area too high a rate can be dangerous; too low a rate can cause malfunction and inaccuracy.

Medical Implants:

• Controlling the porosity of artificial bone allows it to imitate real bone that the body will accept and allow tissue to be grown around it.

Electronics:

• By selecting high surface area material with carefully designed pore networks, manufacturers of super-capacitors can minimize the use of costly raw materials while providing more exposed surface area for storage of charge.

Cosmetics:

• Surface area is often used by cosmetic manufacturers as a predictor of particle size when agglomeration tendencies of the fine powders make analysis with a particle-sizing instrument difficult.

Aerospace:

• Surface area and porosity of heat shields and insulating materials affect weight and function.

Geoscience:

• Porosity is important in groundwater hydrology and petroleum exploration because it relates to the quantity of fluid that a structure can contain as well as how much effort will be required to extract it.

Nanotubes:

• Nanotube surface area and microporosity are used to predict the capacity of a material to store hydrogen.

More Applications:

• Adhesives
• Alloys
• Abrasives
• Carbonates
• Cements
• Clays
• Detergents
• Fibers
• Films
• Fertilizers
• Filters
• Glass
• Food Additives
• Graphite
• Minerals
• Paper
• Polishing Compounds
• Polymers
• Resins
• Soils and Sediments

MicroActive for ASAP2020 Plus

Interactive Data Reduction Software:

• Micromeritics’ innovative MicroActiv software allows you to interactively evaluate isotherm data. You can easily include or exclude data, fitting the desired range of experimentally acquired data points using interactive, movable calculation bars. The isotherm can be viewed real-time on either a linear or logarithmic scale, available to you under each calculation model.

MicroActive reports for ASAP 2020 Plus Physisorption:

• Isotherm
• BET Surface Area
• Langmuir Surface Area
• t-Plot
• Alpha-S Method
• BJH Adsorption and Desorption
• Dollimore-Heal Adsorption and Desorption
• Temkin and Freundlich
• Horvath-Kawazoe
• MP-Method
• DFT Pore Size and Surface Energy
• Dubinin-Radushkevich
• Dubinin-Astakhov
• User Defined Reports

MicroActive for ASAP 2020 Plus Chemisorption:

MicroActive provides you with direct access and manipulation of chemical adsorption isotherm data. Unified Analysis Conditions for physical and chemical analyses allows you to rapidly develop new methods with a common interface.

Reported Data Include:

• Active Metal Surface Area
• Average Crystallite Size
• Irreversible and Reversible Sorption
• Monolayer Capacity
• Active Metal Dispersion

Data Reduction Features:

• Interaction with adsorption data is direct. By simply moving the calculation bars, the user is immediately updated with new textual properties.
• One-click access to important parameters.
• Interactive data manipulation minimizes the use of dialog boxes and tunneling of dialogs to specify calculation parameters.
• Improved ability to overlay files (up to 25) including mercury intrusion data with a file add-and-subtract feature and data from competitive instruments.
• User-selectable data ranges through the graphic interface allow direct modeling for BET, t-Plot, Langmuir, DFT interpretation, and much more. The MicroActive suite provides an extensive selection of NLDFT models for calculating pore size distributions.
• Report Options editor allows the user to define reports with on-screen previews. Each report has the ability to possess one summary, tabular, and graphical information pane.
• Powerful Python programming language allows you to develop extensions to the standard report available within the ASAP 2020 Plus MicroActive application.

Partnership and Support Network:

• Expertise in application assistance is only a phone call away. Every Micromeritics instrument is backed by a dedicated, knowledgeable staff of experts.
• Responsive worldwide service and technical support provides the needed security and peace of mind for you, our customers, ensuring that your sample and product development pathways continue to progress.
• Referenced in an extensive number of peer-reviewed articles in prestigious journals, your ASAP 2020 will link you to a large and growing community of users.

Optional Cryostat:

• A single-stage cryogenic refrigerator that operates on the Gifford-McMahon refrigeration cycle. It uses helium gas from a helium compressor(s) to offer a wide range of analytical temperatures with milli Kelvin levels of stability.

3Flex Chemi-TCD Available Configurations

Included Features of the 3Flex TCD option

Features and Benefits:

Optimum design and efficient utilization of catalysts require a thorough understanding of the surface structure and surface chemistry of the catalytic material. Chemical adsorption analyses can provide much of the information needed to evaluate catalyst materials in the design and production phases, as well as after a period of use.

The ChemiSorb HTP is a fully-automated high-throughput chemisorption analyzer that determines the percent metal dispersion, active metal surface area, size of active particles, and surface acidity of catalyst materials. A major advantage of this instrument is its six analysis stations. Multiple analyses can be run simultaneously or in parallel on one instrument not only saving time for busy catalyst operations, but providing economy of lab space.

The ChemiSorb HTP features a vacuum system and manifold with constantly monitored pressure transducers on each of its six analysis stations. Each port is also equipped with a furnace enabling independent control of sample temperature and ramping from 10 ^oC above ambient to 700 ^oC. The temperature is recorded with each equilibrium pressure to provide the highest quality isotherms possible. An equilibration option allows the user to specify different equilibration times. A mass flow controller is installed in each port to ensure accurate and reproducible flow through the sample. Up to twelve different gases can be attached to the ChemiSorb HTP simultaneously.

Degas/sample preparation is done in-situ prior to analysis. Samples may be added or removed from each station without disturbing the treatment of other samples undergoing preparation or analysis. The instrument features long unattended analysis times and a high-throughput mode that allows the user to start multiple parallel analyses.

The ChemiSorb HTP analysis program operates in a Windows^® environment. This makes operation of the analyzer easier and allows the user to run other applications while an automatic operation is in progress. The report system provided in the analysis program allows the user to manipulate and customize reports in a variety of ways. Zoom in on portions of the graphs or shift the axes to examine fine details. Graphs and data can be copied to the clipboard and pasted into other applications. Reports can be customized with a choice of fonts and a company logo added to the report header.

Features

• High throughput with six analysis stations
• Up to six chemisorption analyses can begin simultaneously
• Independent furnaces for each analysis station features a user defined temperature range from 10 ºC above ambient to 700 ºC.
• Quartz sample reactor with flow-through design, available for various size pellets, core and powders
• Fully automated analysis
• Long unattended analysis times for high resolution adsorption isotherms
• Analysis ports operate concurrently or in parallel
• Up to 12 different gases can be attached simultaneously
• Windows driven software

Chemisorption:

Chemical adsorption is an interaction much stronger than physical adsorption. In fact, the interaction is an actual chemical bond where electrons are shared between the gas and the solid surface. While physical adsorption takes place on all surfaces if temperature and pressure conditions are favorable, chemisorption only occurs on certain surfaces and only if these surfaces are clean. Chemisorption, unlike physisorption, ceases when the adsorbate can no longer make direct contact with the surface; it is therefore a single layer process.

Equipped with many of the features of Micromeritics’ AutoChem II 2920, the AutoChem HP is suitable for a variety of applications including fuel cell and hydrogen storage research.

This microreactor, combined with a mass spectrometer, can also be used to determine product yields and catalytic activity under commercially viable conditions.

The use of a microreactor in the development process is a cost-effective alternative to pilot plants for many development projects. A microreactor is also an affordable option for small start-up companies that cannot afford to invest in a pilot plant to demonstrate their process.

• Allows preparation and analysis of sample at pressures up to 1000 psia with built-in safety checks
• Versatile analysis protocol permits complex sequencing and experimental design
• In situ experiments with virtually unlimited steps
• Records pressure as part of the experiment
• Capable of TPD, TPR, TPO, BET, and pulse chemisorption
• Three mass flow controllers and an electronically controlled pressure regulator provide precise gas control
• Twelve gas inlets – four each for preparation, carrier, and loop gases
• Stainless-steel sample tubes are capable of withstanding temperatures and pressures well above the system’s limits
• An interactive reporting system that includes an extremely versatile graphic user interface allowing custom presentation of results

Bench-top Microreactor Suitable for a Variety of Applications:

• HPTPR (High-pressure TPR) to emulate a commercial activation of a supported metal catalyst
• Fuel cell applications that require reforming hydrocarbon feeds to hydrogen
• Hydrogen storage applications using mixed metal hydrides that change hydrogen capacity as temperature changes – the user can vary hydrogen pressure to determine storage capacity as a function of pressure
• Simple chemical reactions where the product mix changes as a function of pressure – the AutoChem 2950 HP functions as a microreactor at typical process temperatures and pressures, allowing the user to collect reaction data at commercial conditions

AutoChem 2950 HP Software and Reporting

The AutoChem 2950 HP is controlled by powerful Windows-based software. It provides all the convenient features you are accustomed to when using Windowsbased programs. Point-and-click operations, pull-down menus, access to multiple printers and network drives, multitasking capability, and much more are featured in the AutoChem 2950 HP user interface. In addition, the familiar Windows format reduces the time required for training new operators, resulting in fast start-up and increased productivity.

Additional Capabilities

An Instrument Schematic screen displays the instrument’s current operating status, including the availability of analysis and pretreatment gases and vapors, direction of the gas flow, TCD reading, and allows the operator to assume manual control of the instrument if desired.

Set up Analysis Protocol Sequencing from any number of preprogrammed experiments or create a customized sequence. The user can easily select the pretreatment and analysis task, and specify criteria such as temperature ramp rates, gas flow rates, and data measurement intervals in the desired sequence. Modifications may be made to the analysis protocol at any time, even during analysis.

Fully integrated, interactive peak editor package enables the user to evaluate results quickly and easily, edit peaks, and produce reports that reflect specific needs. Adjusting peak boundaries is a matter of simply pointing and clicking. The peak editor can also be used to de-convolute overlapping peaks. The peak de-convolution is a simple-to-use option on the peak space editor that allows the user to maximize the information.

Numerous plots can be overlaid for easy comparison of different samples or for comparison of different data reduction techniques applied to the same sample. The operator can also plot two externally derived signals against time or sample temperature (e.g., mass spectrometer and gas chromatograph).

Integration of mass spectrometer data files, which allows the manipulation of the TCD and mass spectrometer simultaneously.

One computer can control two Micromeritics AutoChem HP analyzers making efficient use of valuable lab space.

AutoChem 2950 HP Hardware Features

The AutoChem HP features stainless-steel construction, fully automated flow control and pressure control, an embedded microprocessor with real-time control, and an intuitive graphical user interface for reactor control. Like the AutoChem 2920, the AutoChem 2950 HP features a temperature-controlled, stainless-steel flow path to provide a stable inert operating environment and reduce the potential for condensation in the flow path. The embedded microprocessor allows the AutoChem series to operate with real-time control; this provides enhanced stability by separating the AutoChem control from a PC or workstation

Twelve gas inlets (4 each for preparation, carrier, and loop) provide the capability to perform sequential experiments such as TPR/TPO cycle experiments.

Equipped with high-precision, independently calibrated mass flow controllers providing extremely accurate, programmable gas control. The ability to control gas flow with accuracy assures a stable baseline and accurate determination of gas volumes.

Analysis gas may be introduced to the carrier stream by a precision automated loop. A conveniently located septum is also provided through which analysis gas can be injected by means of a calibrated syringe.

Thermal conductivity detector (TCD) is capable of detecting minute differences in the concentration of gases flowing into and out of the sample reactor. Its corrosion-resistant filaments are operated at constant temperature to prevent thermal runaway, which can destroy filaments in other systems.

A clamshell furnace can heat the quartz sample reactor up to 1100 °C. The AutoChem 2950 HP permits any number of ramp rates and sequences to facilitate customized experiments. The included KwikCool feature permits cooling the furnace temperature rapidly down to near ambient, reducing analysis time and increasing throughput. With the CryoCooler option, analysis temperatures can be ramped over the range of -100 °C to 1100 °C.

Four internal temperature-controlled zones can be heated independently of each other to as much as 150 °C. This prevents condensation in the flow path and allows studies to be performed with vapors.

The extremely low volume of the internal plumbing minimizes peak spreading and significantly enhances peak resolution. Furthermore, it reduces the time lag between sample reactions and the corresponding detector response.

A cold trap can remove certain substances before the gas flow reaches the detector. The cold trap can also be used as a delay path for BET surface area experiments.

Injection loops are provided for injecting carefully measured doses of gases for analyses such as pulse chemisorption. The AutoChem HP is shipped with a 1.0-cm3 loop installed; 0.5- and 5.0-cm3 loops are also included. If sample fi les are set up so that a loop is used for introducing gas into the analyzer, the instrument automatically doses the sample as specified in the sample file.

Stainless-steel sample tubes are capable of safe operation up to 1500 psia

AutoChem 2950 HP Technique Overview

An Example of Use

Consider a temperature-programmed reduction (TPR) in which a metal oxide is reacted with hydrogen to form a pure metal, in this case platinum. Argon, which has a very low thermal conductivity, is used as a carrier gas. It is blended in a fixed proportion with hydrogen, an analysis gas with a much higher thermal conductivity. Then the gas mixture flows through the analyzer, through the sample, and past the detector.

When the gas blend begins flowing over the sample, a baseline reading is established by the detector. This baseline is established at a low enough temperature so that no reduction of the sample is occurring. The proportion of gases flowing over the detector is the same as the proportion of gases entering the analyzer, because at the low temperature, there is no interaction.

The temperature is then gradually increased and when a critical temperature is reached, hydrogen atoms in the gas flow react with the sample, forming H2O molecules which are removed from the gas stream using a cold trap. As a result, the amount of hydrogen in the argon/hydrogen gas blend decreases and the proportion between the two gases shifts in the direction of argon, as does the mixture’s thermal conductivity.

Since argon has a lower thermal conductivity than hydrogen, the mixture’s thermal conductivity consequently decreases. The flowing gas removes heat from the filament more slowly, requiring less electricity to maintain a constant filament temperature. The instrument records the electrical demands as it changes (this is called the detector signal). The detector signal is recorded continuously over a range of temperatures. The resulting signals may present either positive or negative peaks.

This example illustrates the fundamental concept upon which the analyzer operates. Of course, the various types of analyses the AutoChem can perform result in different types of traces. For example, a pulse chemisorption analysis results in a series of peaks that gradually increases in size as the sample is dosed with separate but equal increments of gas. Initially, the gas uptake by the sample results in smaller peaks. But when all the active sites are saturated, no more gas can be taken up and the peaks become equal.

Chemisorption:

Chemical adsorption is an interaction much stronger than physical adsorption. In fact, the interaction is an actual chemical bond where electrons are shared between the gas and the solid surface. While physical adsorption takes place on all surfaces if temperature and pressure conditions are favorable, chemisorption only occurs on certain surfaces and only if these surfaces are clean. Chemisorption, unlike physisorption, ceases when the adsorbate can no longer make direct contact with the surface; it is therefore a single layer process.

AutoChem 2950 HP Applications

Catalyst

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

Cirrus 3 Quadrupole Mass Spectrometer

Atmospheric Pressure Gas Monitoring

Building on proven Cirrus Quadrupole Mass Spectrometry technology, the Cirrus 3 combines state-of-the-art performance in compact benchtop and rack-mounted formats. With a heated capillary inlet and fast scan speed (250 points per second), gas compositions can be tracked over wide dynamic range (ppb to percentage levels) more reliably.

• Monitors multiple gas species from trace levels (ppb) to high abundance
• Fast response – 250 data points per second & capillary inlet heated up to 300°C
• Precise and stable user-defined temperature control with enhanced oven and capillary designs
• Detect gases up to 300 amu. High resolution options (1-100HP)
• Recipe-driven Process Eye Professional supports gas monitoring and quantitation applications
• Fast and Reproducible Data

Cirrus systems are based on Quadrupole Mass Spectrometry, widely acknowledged as a preferred platform technology for many atmospheric pressure gas analysis applications. The Cirrus 3 system, with its improved temperature control and compact design, provides high levels of performance and robustness in space-efficient and flexible configurations that are ideal for a wide range of analytical applications.

Precision engineered to provide fast and reproducible data, Cirrus 3 can accurately detect and quantify gases and gas mixtures, from one or more sampling locations with a single instrument. Gas composition can be monitored over a wide dynamic range, from percentage levels down to the sub ppm range.

Cirrus 3 is an ideal choice for atmospheric gas analysis whether you work in a research setting or a manufacturing environment. By combining Process Eye Professional software with MKS technical support, Cirrus can be integrated, optimized, and automated to your precise specifications. Ultimately, users across your organization realize greater benefits of the power of quadrupole mass spectrometry.

Quadrupole Analyzer

At the heart of every Cirrus 3 system is a precision-built quadrupole analyzer incorporating a closed ion source, a triple mass filter, and a dual (Faraday and Secondary Electron Multiplier) detector system. This analyzer configuration is selected to optimize sensitivity and longterm performance stability

The Cirrus 3 system enables the AutoChem II 2920 and AutoChem 2950 HP to function as multi-component microreactors. Cirrus 3 software includes Process Eye Professional which controls analyzer data collection and monitors real-time data and analyzer status.

A Recipe wizard helps create and configure analysis conditions. The Micromeritics/Cirrus interface software runs inside Process Eye Professional and is accessed via its own menu.

This interface enables the user to control the analyzer via recipes which can also be saved for future use. The interface allows the user to collect data automatically from the AutoChem, customize Peak Jump recipes, access standard operations, calibrate detectors, and scale the AutoChem sample thermocouple signal.

Data integration with AutoChem II 2920 and AutoChem 2950 HP

• MS data may be analyzed using the Micromeritics Peak Editor that allows signal deconvoution (peak fitting), signal integration, and smoothing.
• The AutoChem software may be used to create MS calibrations and convert raw signals to quantitative analyses.
• Data may be used directly in AutoChem characterization reports: dispersion, active area, kinetics, crystallite size.

Features and Benefits:

• Monitors multiple gas species over a wide dynamic range of composition at atmospheric pressure
• Compact, modular design for ease of serviceability and maintenance
• Direct Ethernet interface – fully network compatible
• Recipe driven Process Eye Professional software for automated operation and calibration
• Fast response, silica capillary inlet heated to 150° C

For sampling different gas conditions, inlet options available are:

• Stainless steel capillary
• Low flow capillaries
• Multi-stream inlets
• Automated variable pressure inlet

Applications

• Monitoring of trace contaminants in process gas
• Catalyst studies
• Fuel cell monitoring and development
• Heat treatment/furnace monitoring
• Membrane studies
• Glove box gas monitoring
• Lamp manufacture
• Gas supply monitoring (cylinder checks and special gas production)
• Freon detection and identification
• Environmental monitoring. Thermal analysis – TGA, DTA
• Fermentation process monitoring