Modified Y molecular sieve with its surface rich in mesopores, and preparation method thereof

Abstract

The invention relates to a modified Y molecular sieve with its surface rich in mesopores, and a preparation method thereof. A molar ratio of the bulk phase SiO2 / Al2O3 of the modified Y molecular sieveis 10.0 to 13.0; the modified Y molecular sieve has a BET-process total pore volume of no less than 0.38 cm <3> / g and a BET-process secondary pore volume of no less than 0.06 cm <3> / g; the cell parameters a, b and c are equal and are in a range of 2.44-2.46 nm; and the content of sodium oxide in the modified Y molecular sieve is not more than 0.1 wt% based on the total weight of the modified Y molecular sieve. Compared with conventional Y molecular sieves, the modified Y molecular sieve of the invention has a larger surface mesoporous volume.

Description

technical field [0001] The disclosure relates to a modified Y molecular sieve whose surface is rich in mesopores and a preparation method thereof. Background technique [0002] At the end of the 1950s, Milton and Breck successfully synthesized Y-type molecular sieves. Due to the structure of NaY molecular sieves, SiO 2 / Al 2 o 3 The ratio is greater than that of X-type molecular sieve, so that its thermal stability and water stability are improved. In the early 1970s, Grace Company developed the directing agent method to synthesize NaY molecular sieves. The raw material was water glass instead of expensive silica sol. The process was simplified and the growth cycle was shortened, so that NaY molecular sieves were rapidly and widely used in petrochemical industries Petroleum cracking catalysis field. So far, among the hundreds of molecular sieves that have been developed, Y molecular sieve is the most widely used in industry. At present, the synthesis of NaY molecular si...

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Problems solved by technology

The dealumination process of molecular sieves is a complex and difficult to control process. The removal of aluminum is very sensitive to dealumination conditions, and it is difficult to achieve the same degree of dealumination on the surface of the catalyst as in the bulk phase. Usually, the aluminum on the surface of molecular sieves is easier to remove, while To remove the aluminum in the bulk phase of the molecular sieve, more severe dealumination conditions are required, which will cause the collapse of the molecular sieve skeleton structure and the destruction of the micropores. The structure and acid properties have a great influence

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