A molecular sieve has a silica/alumina molar ratio of 100-300, and has a mesopore structure. One closed hysteresis loop appears in the range of P/P.sub.0=0.4-0.99 in the low temperature nitrogen gas adsorption-desorption curve, and the starting location of the closed hysteresis loop is in the range of P/P.sub.0=0.4-0.7. The catalyst formed from the molecular sieve as a solid acid not only has a good capacity of isomerization to reduce the freezing point, but also can produce a high yield of the product with a lower pour point. The process for preparing the catalyst involves steps including crystallization, filtration, calcination, and hydrothermal treatment.

A molecular sieve has a silica/alumina molar ratio of 100-300, and has a mesopore structure. One closed hysteresis loop appears in the range of P/P.sub.0=0.4-0.99 in the low temperature nitrogen gas adsorption-desorption curve, and the starting location of the closed hysteresis loop is in the range of P/P.sub.0=0.4-0.7. The catalyst formed from the molecular sieve as a solid acid not only has a good capacity of isomerization to reduce the freezing point, but also can produce a high yield of the product with a lower pour point. The process for preparing the catalyst involves steps including crystallization, filtration, calcination, and hydrothermal treatment.

A phosphorus-containing or phosphorus-modified ZSM-5 molecular sieve is characterized in that in its 27Al MAS-NMR, the ratio of peak area for the resonance signal having a chemical shift of 39±3 ppm to peak area for the resonance signal having a chemical shift of 54 ppm±3 ppm is ≥1; or in its surface XPS elemental analysis, the value of n1/n2 is ≤0.1. n1 represents the mole number of phosphorus, n2 represents the total mole number of silicon and aluminum. A cracking auxiliary or cracking catalyst contains the phosphorus-containing/phosphorus-modified ZSM-5 molecular sieve can be made using the phosphorus-containing or phosphorus-modified ZSM-5 molecular sieve.

A phosphorus-containing or phosphorus-modified ZSM-5 molecular sieve is characterized in that in its 27Al MAS-NMR, the ratio of peak area for the resonance signal having a chemical shift of 39±3 ppm to peak area for the resonance signal having a chemical shift of 54 ppm±3 ppm is ≥1; or in its surface XPS elemental analysis, the value of n1/n2 is ≤0.1. n1 represents the mole number of phosphorus, n2 represents the total mole number of silicon and aluminum. A cracking auxiliary or cracking catalyst contains the phosphorus-containing/phosphorus-modified ZSM-5 molecular sieve can be made using the phosphorus-containing or phosphorus-modified ZSM-5 molecular sieve.

A phosphorus-modified MFI-structured molecular sieve is characterized in that the molecular sieve has a K value, satisfying: 70%≤K≤90%; for example, 75%≤K≤90%; further for example, 78%≤K≤85%. The K value is as defined in the specification. A cracking auxiliary or cracking catalyst contains the phosphorus-modified MFI molecular sieve.

A GIS-type zeolite having a carbon atom content of 4% by mass or less and a silica-alumina ratio of 4.23 or more, wherein the GIS-type zeolite satisfies at least one of the following conditions (i) and (ii) in a spectrum obtained by X-ray diffraction: (i) when heights of peaks around 2θ=12.45 and 28.07° are respectively defined as A and B, 0.62≤A/B is satisfied; and (ii) when heights of peaks around 2θ=28.07 and 46.04° are respectively defined as B and C, 11.5≤B/C is satisfied.

A GIS-type zeolite having a carbon atom content of 4% by mass or less and a silica-alumina ratio of 4.23 or more, wherein the GIS-type zeolite satisfies at least one of the following conditions (i) and (ii) in a spectrum obtained by X-ray diffraction: (i) when heights of peaks around 2θ=12.45 and 28.07° are respectively defined as A and B, 0.62≤A/B is satisfied; and (ii) when heights of peaks around 2θ=28.07 and 46.04° are respectively defined as B and C, 11.5≤B/C is satisfied.

The catalyst for producing aromatic hydrocarbon is for producing monocyclic aromatic hydrocarbon having 6 to 8 carbon number from oil feedstock having a 10 volume % distillation temperature of 140° C. or higher and a 90 volume % distillation temperature of 380° C. or lower and contains crystalline aluminosilicate and phosphorus. A molar ratio (P/Al ratio) between phosphorus contained in the crystalline aluminosilicate and aluminum of the crystalline aluminosilicate is from 0.1 to 1.0. The production method of monocyclic aromatic hydrocarbon is a method of bringing oil feedstock having a 10 volume % distillation temperature of 140° C. or higher and a 90 volume % distillation temperature of 380° C. or lower into contact with the catalyst for producing monocyclic aromatic hydrocarbon.

The catalyst for producing aromatic hydrocarbon is for producing monocyclic aromatic hydrocarbon having 6 to 8 carbon number from oil feedstock having a 10 volume % distillation temperature of 140° C. or higher and a 90 volume % distillation temperature of 380° C. or lower and contains crystalline aluminosilicate and phosphorus. A molar ratio (P/Al ratio) between phosphorus contained in the crystalline aluminosilicate and aluminum of the crystalline aluminosilicate is from 0.1 to 1.0. The production method of monocyclic aromatic hydrocarbon is a method of bringing oil feedstock having a 10 volume % distillation temperature of 140° C. or higher and a 90 volume % distillation temperature of 380° C. or lower into contact with the catalyst for producing monocyclic aromatic hydrocarbon.

Disclosed are a phosphorus-containing high-silica molecular sieve, its preparation and application thereof, wherein the molecular sieve comprises about 86.5-99.8 wt % of silicon, about 0.1-13.5 wt % of aluminum and about 0.01-6 wt % of phosphorus, calculated as oxides and based on the dry weight of the molecular sieve, the molecular sieve has an XRD pattern with at least three diffraction peaks, the first strong peak is present at a diffraction angle of about 5.9-6.9°, the second strong peak is present at a diffraction angle of about 10.0-11.0°, and the third strong peak is present at a diffraction angle of about 15.6-16.7°. The phosphorus-containing high-silica molecular sieve shows an improved hydrocracking activity in the presence of nitrogen-containing species when used in the preparation of hydrocracking catalysts.