A zeolite with strong acidity and high hydrocracking activity, rey zeolite has been found to be suitable for use in the petrochemical industry.rey zeolite Its use in fluid catalytic cracking processes results in a wide range of products such as ethylene and propylene, methylcyclohexane, methanol, and other aromatic compounds. It has also been used in the production of naphthalene, a chemical precursor to acrylonitrile and other nylons.
Rey zeolite has also been demonstrated to exhibit exceptional catalyst properties in hydroisomerization reactions such as benzene dectring, cumene metathesis, and the alkylation of isopropylbenzene.rey zeolite It has excellent resistance to sulfur and nitrogen poisoning, making it an ideal candidate for use in the petrochemical industry.
The present invention provides a method of producing an enantiomorphically pure S-type rey zeolite (STW).rey zeolite It is based on the innovative synthesis strategy that employs sugar-derived organic structure directing agents. The general synthetic route of the synthesis is described in Suppl. 1, along with X-ray diffraction patterns of the resulting zeolites and their compositions.
In a typical synthesis, the crystalline STW zeolite is prepared from a solution of sodium silicate in water, in which a chiral organic structure directing agent has been added. The synthesis gel is then placed in stainless steel autoclaves and subjected to constant tumbling at 175 degC for five days, during which the crystal structure of the zeolite forms.
When a chiral OSDA is used in zeolite synthesis, it is essential to ensure that the resulting zeolites are enantiomorphically pure. Several methods for confirming the handedness of crystalline materials, including advanced electron microscopy techniques32 and circular birefringence of zeolite crystals, have been developed34. However, it has remained a challenge to confirm the absolute configuration of zeolitic structures using these techniques, largely because of the complexity of their crystal structures and the existence of racemic mixtures in the crystalline phase.
A series of ultrastable Y-type zeolites (Si/Al12.5-x/REx) has been produced by partially exchange with RE in order to study the effect of the RE content on the number and the strength of acid sites. The acidic properties of the zeolites were determined by FT-IR spectroscopy with pyridine as the probe molecule. The results showed that the zeolite with a higher RE content displayed more acidic extraframework BAS and less weaker Bronsted acid sites in supercages. The optimum acidity of the USY zeolite was achieved at a RE content of about 8%. This zeolite was also characterized in terms of its hydrocracking and hydroisomerization activities, as well as its adsorption ability of linear paraffins. It was found that this zeolite exhibits the highest activity for hydrocracking and the best catalytic performance in hydroisomerization of isopropylbenzene. The synthesis and characterization of this zeolite is expected to provide new alternatives for applications in fluid catalytic cracking and hydroisomerization. Moreover, it may be suitable for methanol arylation and the dectring of phthalene.
Tags:hy zeolite catalyst
