Andrew D. D’Amico, part of the scientific services group specializing in characterization by physical and chemical adsorption, recently attended the spring 2013 meeting of the American Society for Testing and Materials (ASTM) catalyst committee (D32). For this meeting, Andrew prepared material for three topics of interest: static carbon monoxide (CO) chemisorption on supported platinum on alumina catalysts, dynamic carbon monoxide pulse chemisorption on supported platinum on alumina catalysts, and dynamic acid site characterization of zeolites by propylamines. Andrew also contributed to the discussion to keep and update the current standard of terminology relating to catalysts and catalysis (D3766).
Platinum supported on alumina, Pt/Al2O3, is used commercially in reforming and isomerization during crude oil refining and is used as a reference material for the ASAP 2020C and AutoChem II 2920. Static chemisorption of CO is the reference analysis for the ASAP 2020C, and the pulse chemisorption is the reference analysis for the AutoChem. While a static method for hydrogen chemisorption (D3908) already exists, CO chemisorption analyses provide alternate methods to investigate metal surface area and dispersion—especially when spillover is a concern. The static method is ready for inter-laboratory testing, and the dynamic method should be to this stage of development soon. Therefore, Micromeritics works to establish and use methods recognized and accepted by a national standards organization.
Characterization of acidity of solid materials is also important for hydrocracking, oligimerization, and other applications of acid catalysts. The only standard method currently available involves static ammonia chemisorption (D4824). The new dynamic method using propylamines allows for quantification of the acid sites as well as assessment of the strength of acid sites by temperature-programmed desorption. Reproducibility studies have already been done on commercially available zeolites. Minor refinements were made to the proposed method prior to this meeting, and the method should be available for inter-laboratory testing soon.