Catalyst and Adsorbent

ZeoHte catalysts and adsorbents are widely accepted in industry. Commercial adsorbents based on synthetic aluminosihcates zeolite A and X became available in 1948 [4]. Zeolite Y as FCC catalyst became commercially available in 1964 [5]. 

The majority of heterogeneous chemical and physical-chemical processes lead to formation of the intermediate particles - free atoms and radicals as well as electron- and oscillation-excited molecules. These particles are formed on the surface of solids. Their lifetime in the adsorbed state Ta is determined by the properties of the environment, adsorbed layer, and temperature. In many cases Ta of different particles essentially affects the rate and selectivity of heterogeneous and heterogeneous-homogeneous physical and chemical processes. Therefore, it is highly informative to detect active particles deposited on surface, determine their properties and their concentration on the surface of different catalysts and adsorbents. 

THE CHESSBOARD AND THE PIECES CATALYST AND ADSORBED SPECIES CHARACTERIZATION... 

Although relaxation measurements have been widely used in nuclear magnetic resonance studies of solid catalysts and adsorbed molecules, they have not found such favor in similar ESR work. Relaxation phenomena, however, do play a very important role in any magnetic resonance experiment, whether or not this aspect of the problem is studied. In fact, the temperature at which most ESR experiments are conducted is dictated by the relaxation process. Furthermore, even qualitative data on relaxation times can be used as supporting evidence in the identification of a paramagnetic species. 

PURASPEC A process for purifying gaseous and liquid hydrocarbons by the use of fixed beds of catalysts and adsorbents which remove impurities by chemical reaction. Developed in 1990 by ICI Katalco to enable natural gas and natural gas liquids to meet pipeline specifications. Installed in approximately 60 plants worldwide in 1996. 

Catalyst and adsorbent could be easily manufactured 2. The proprietary composition is difficult to imitate. 1. Catalyst is relatively new technology for indoor air cleaners 2. Regenerable adsorbent is new for the industry. 

Entrepreneurship and Product Design in Chemical Engineering Education 12.7 CATALYST AND ADSORBENT... 

The project team s main objective is to design an efficient indoor air quality control appliance that can achieve the most stringent IAQ standard using new and competitive catalyst and adsorbent technologies. The appliance must be... 

The prototype design 2 was expected to have similar air seal problems as the prototype 1 therefore the prototype design 3 was constructed and tested, instead. Since all the modification was restricted to the wheel, prototype design 3 allowed us to simply use the existing commercial appliance design. The dehumidifier was first test run under different operating conditions and the airflow, temperature and humidity at different locations within the appliance were measured and recorded. The airflow, temperature and humidity profiles were used to calculate the optimum quantities and distributions of catalysts and adsorbents in the wheel (Fig. 12.8-6). The wheel was replaced in the dehumidifier appliance and tested with sensors inserted at the locations shown in Fig. 12.8-11. The results show that the airflows and temperatures remained within normal operating values. Laboratory and field tests were conducted and the results are reported in the next section. 

Synthesis of Zeolites and Manufacture of Zeolitic Catalysts and Adsorbents... 

Catalyst and adsorbent finishing procedures are outlined including preparation of binder-free forms, zeolite stabilization procedures, ion exchange and metal loading procedures, and drying and firing operations. 

Finally, new developments in zeolite catalyst and adsorbent manufacture will be outlined in the form of a survey of recent open and patent literature. Patents are extensively cited as reference materials for this chapter however no effort is made to identify specific manufacturing techniques actually used by any particular company to manufacture zeolites or any catalytic or adsorbent products. This is because there is no way to determine whether manufacturing patents are practiced as is or whether further refinements have been accomplished subsequent to the filing of the patents that may be held by specific companies as trade secrets. 

The health, safety and environmental (HS E) aspects of manufacturing zeolites and the ultimate catalyst and adsorbent materials derived from them are the most important issues with respect to a maintaining a sustainable zeolite business. A recent paper treats some of these HS E issues in a cursory way [1]. Treatment of this subject is beyond the scope of this chapter, but the unique HS E issues... 

Many procedures that are used in zeolite catalyst and adsorbent manufacture are common to other manufactured products. The unit operahons and equipment that are used can therefore be found throughout the catalyst and adsorbent manufacturing industries. There are a number of books and monographs that outhne equipment and manufacturing procedures that are relevant to zeoHte catalysts and adsorbents [65-68]. 

Zeolite catalysts and adsorbents have also been incorporated into monolithic contactors by several routes, including extruded zeoHte/binder composites [70], wash-coated ceramic monoliths [71] and corrugated thin-sheet monoliths [72]. 

Finishing Post-Forming Manufacturing of Zeolite Catalysts and Adsorbents 71... 

Characterization is an integral tool for the development of new zeolites and for the development and commercialization of zeolitic catalysts and adsorbents. Single techniques are not sufficient as they rarely provide full details of the system. A combination of selective characterization techniques is required. As suggested by Deka [1] even a single acidity characterization method may be insufficient to provide the necessary detailed information to understand the zeolite acid sites. Thus according to Deka the combination of different experimental techniques is required to shorten the time of development for a new catalyst. 

The purpose of this chapter is to provide general guidance for the various characterization techniques that are most often employed in the development and commerciaHzation of new zeolites, catalysts and adsorbents. Each of these techniques can be a volume unto itself. Thus we only briefly describe the technique but emphasize the information that can be obtained by the particular method and the utiHty of that information for characterizing zeoHtes, zeolitic catalysts and zeoHtic adsorbents. The Hmitations of the various techniques are included to assist the novice. For a more in depth understanding of the various techniques, references are given throughout the chapter. 

Chapter 3 outlines zeolite synthesis, modification and the manufacturing of zeolite-based catalysts and adsorbents. Extensive patent references are given to provide the reader with a historical perspective. Some of the pitfalls associated with the operation of synthesis and manufacturing units are also described. 

Characterization is the foundahon for the development and commercialization of new zeolites and zeolite-containing catalysts and adsorbents. Chapter 4 provides an overview of the most commonly employed characterization techniques and emphasizes the uhlity and limitations of each of these methods. An example is provided as to how a multi-technique characterization approach is necessary in order to determine the structure of a newly invented zeolite. Techniques covered in this chapter include X-ray powder diffraction, electron microscopy, infrared (IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and physical/ chemical methods. 

---