Minimum Surface Area Measurements with Micromeritics Physisorption Analyzers

A frequently asked question is “how much sample is required for a surface area analysis?” The simple answer is that it depends: it depends on the type of instrument being used for the measurement, and its accepted measurement tolerance; it depends on the type of sample tube being used for the measurement, which affects the […]

Introduction to Chemical Adsorption Analytical Techniques and their Applications to Catalysis

Abstract The chemical adsorption isotherm reveals information about the active surface of a material and has been employed for many years as a standard analytical tool for the evaluation of catalysts. Temperature-programmed reaction techniques have emerged from the 1950’s as an indispensable companion to chemisorption isotherm analyses in many areas of industry and research. This […]

The Heat of Adsorption of Hydrogen Gas on Lanthanum Pentanickel

by: Reid Davis Lanthanum pentanickel (LaNi5) is a metal alloy that, under the correct pressure and temperature conditions, will rapidly sorb hydrogen gas and form a metal hydride compound. Hydride forming metal compounds are well known for their ability to sorb large amounts of hydrogen gas at a specific pressure, store it, and later release […]

Diffusion of Nitrogen and Methane in Clinoptilolites – Tailored for N2/CH4 Separation

Ambalavanan Jayaraman and Ralph T. Yang* *Department of Chemical Engineering, University of Michigan Ann Arbor, Michigan 48109, USA Introduction Upgrading production from the aging natural gas wells by non-cryogenic separation of nitrogen from methane continues to be a topic of intense research. New nano-structured sorbent materials have been developed in the recent past for the […]

Carbon Dioxide Characterization of Carbons with the TriStar II 3020

Introduction The use of carbon dioxide allows for rapid, high-resolution characterization of microporous materials. The Micromeritics TriStar II 3020 can be used to characterize micropores below 10 angstroms within 8 hours using CO2 as the adsorptive gas and an ice bath (273 K) for the analysis bath. Isotherms from CO2 adsorption were compared with N2 […]

The Surface Area of Magnesium Stearate — An Excipient Used In Pharmaceuticals

Magnesium stearate is widely used in the pharmaceutical industry as an excipient in tableted drugs. The physical properties of the magnesium stearate influence the tableting characteristics of the formulation as well as the in vivo degradation and dissolution of the solid drug. The United States Pharmacopia, which has already established a standard for the particle […]

Liquid Nitrogen Level When Using Isothermal Jackets

When isothermal jackets are used, it is important not to overfill the liquid nitrogen in the Dewar. At the start of an analysis, the liquid nitrogen level should be no higher than 1/4 in. (0.64 cm) from the top of the isothermal jacket. Overfilling overrides the function of the isothermal jacket and prevents effective control […]

Can I Calculate Density From Free Space

A frequent question is often posed by users, can density be calculated from free space measured on a gas adsorption analyzer instead of using an instrument that is designed to obtain density? This tech note will explore the possibility of using such a method and compare with results obtained by the Micromeritics AccuPyc II. Gas […]

Expanding the Material Characterization “Toolbox” for Excipient and Active Pharmaceutical Ingredient (API) Vendor Qualification

Physical characterization of pharmaceutical excipients is not only a requirement but can also provide data that can be predictive in nature regarding the performance of final dosage forms including tablets, capsules, inhaled dosage forms, transdermals, and others. Manufacturers generally provide some of this physical testing data, such as particle size. In the case of particle […]

Degas Backfill Gas Selection for Micromeritics Gas Adsorption Instruments

Introduction Specific surface areas and pore volume distributions are often determined using gas adsorption techniques. Prior to analysis, any adsorbed gas or vapor phase (such as water or other volatiles) should be removed from the sample. This process is often referred to as degassing the sample. Degassing usually involves either heating the sample or flowing […]