1. Field of the Invention
The present invention relates to a crystalline zeolite, more specifically a barium-exchanged crystalline zeolite X (or a barium cation form type-X crystalline zeolite). The present invention also relates to an agglomerate comprising the above-mentioned crystalline zeolite and a binder material, which is suitable for use as an adsorbent for selective removal and/or separation of a specific component such as carbon monoxide, oxygen, carbon dioxide, and water vapor from a fluid stream containing the same.
2. Description of Related Art
It is well known in the art that natural or synthetic zeolites are industrially utilized for drying, purification, recovery, and/or separation of various fluids such as hydrocarbon streams and atmospheric air employing the adsorptive properties of the components in the fluids on the zeolites. The effectiveness of the treatments of a fluid stream such as drying, purification, recovery and/or separation depends upon the type of zeolite to be used as well as the components of a fluid to be treated. For example, Na-A zeolite (or sodium cation form type-A crystalline zeolite) pellets comprising crystalline zeolite Na-A and a clay mineral as main constituents can adsorb molecules having size and shape to permit entrance through a micro-pore of 3.8 angstroms such as water vapor, hydrogen sulphide, carbon dioxide, ethane, ethyl alcohol and butadiene, while other molecules such as porpane, cyclic hydrocarbons and compressor oil being excluded. The Na-A zeolite pellets, therefore, have been advantageously utilized as an adosrbent for such as natural gas and solvent drying, carbon dioxde removal from natural gas streams. Furthermore, Na-X zeolite pellets comprising crystals of Na-X zeolite having rational formula of: EQU Na.sub.86 [(AlO.sub.2 86 (SiO.sub.2).sub.106 ].multidot.276H.sub.2 O
and a clay mineral as main constituents can adsorb molecules smaller than an effective diameter of 10 angstroms such as iso-paraffins, iso-olefins and di-n-butylamine and exclude molecules having a large diameter of more than 10 angstroms such as tri-n-butylamine, and have been employed for the purposes of for example, simultaneous removal of moisture and carbon dioxide from fluid streams containing the same or the removal of sulphur compounds from hydrocarbon streams containing the same.
It is also known in the art that the entire or partial exchange of the cation in a crystalline zeolite to another has a marked effect on its adsorptivity and cation-exchanged forms of Na-form zeolites such as calcium- and potassium-forms are used depending upon services therewith. Barium-exchanged form zeolites, however, have not been of wide prevalence in industrial services, although some of the said forms have been proposed. For example, barium form zeolite X prepared by exchanging 90% or more of sodium cation in the above-mentioned zeolite Na-X with corresponding barium is described in, for example, U.S. Pat. No. 2,882,244. The Ba-form zeolite X exhibits the desirable separation property of various sorbates such as nitorogen and oxygen. However, the desirable separation property of the conventional barium-form zeolite X is susceptible to be impaired during processing, i.e., the blending of the barium-form zeolite and the binder, the fashioning of the mixture into suitable forms and the firing of the formed material at elevated temperatures has prevented the prevalence thereof in the practical use.
One the other hand, although the above-mentioned Na-X zeolite has been employed for the above-mentioned purpose, for example, as an industrial adsorbent for separation and/or removal, it is still not satisfactory for some uses as an adsorbent, for example, the separation of carbon monoxide and nitrogen and the separation of oxygen and nitrogen of atmospheric air.