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Modified MFI structure silicon-aluminum molecular sieve and preparation method thereof

A silicon-alumina molecular sieve, molecular sieve technology, applied in molecular sieve catalysts, chemical instruments and methods, physical/chemical process catalysts, etc., can solve the problem of reduced pore volume and specific surface area, insufficient coordination between phosphorus and framework aluminum, and poor propylene yield. High problems, to achieve excellent cracking conversion rate and, improve hydrothermal stability, the effect of high liquefied gas yield

Active Publication Date: 2022-07-08
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the propylene yields in their disclosures are not high
Although HZSM-5 molecular sieve has good shape-selective performance and isomerization performance, its disadvantage is poor hydrothermal stability, and it is easy to deactivate under harsh high-temperature hydrothermal conditions, which reduces the catalytic performance.
[0010] Although, modifying the ZSM-5 molecular sieve with an appropriate amount of inorganic phosphide can slow down the framework dealumination and improve the hydrothermal stability, and the phosphorus atom will combine with the distorted four-coordinated framework aluminum to form a weak B acid center, thereby achieving Higher conversion rate of long-chain alkane cracking and higher selectivity of light olefins, but excessive inorganic phosphide used to modify ZSM-5 molecular sieve will block the pores of molecular sieves and reduce pore volume and specific surface area , and occupy a large number of strong B acid centers
Moreover, when inorganic phosphorus is modified by phosphorus in the prior art, phosphoric acid or ammonium phosphate salt will self-polymerize to generate phosphorus species in different aggregation states during the roasting process when excessive phosphorus compounds are used, and the dispersion of phosphorus species is poor, resulting in phosphorus and ammonium phosphate Insufficient coordination of framework aluminum, low efficiency of phosphorus utilization, phosphorus modification does not always result in satisfactory improvement of hydrothermal stability

Method used

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  • Modified MFI structure silicon-aluminum molecular sieve and preparation method thereof
  • Modified MFI structure silicon-aluminum molecular sieve and preparation method thereof
  • Modified MFI structure silicon-aluminum molecular sieve and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1-1

[0032] Take 18.5 g of diammonium hydrogen phosphate and 108 g of hydrogen-type hierarchical porous ZSM-5 molecular sieve (provided by Qilu Branch of Sinopec Catalyst Company, the relative crystallinity is 88.6%, the molar ratio of silica / alumina is 20.8, Na 2 The O content was 0.017 wt%, and the specific surface area was 373 m 2 / g, the total pore volume is 0.256 ml / g, the mesopore volume is 0.119 ml / g, the average pore diameter is 5.8 nm, the same below) and 60 g of deionized water were mixed into a slurry, heated to 100 ° C and kept for 2 hours. The phosphorus-containing hierarchical porous ZSM-5 molecular sieve was obtained after drying in an oven at 110°C and air calcination at 550°C for 2 h. Dissolve 1.8g of ferric nitrate in 60g of deionized water again, and use the impregnation method to modify it with the obtained phosphorus-containing ZSM-5 molecular sieve sample. The multi-level porous ZSM-5 molecular sieve sample is GPMZ1-1.

Embodiment 1-2

[0036] Same as Example 1-1, the difference is that after drying, it is treated at 450°C and 60% water vapor for 0.5h to obtain a phosphorus and iron modified hierarchical porous ZSM-5 molecular sieve sample, denoted as GPMZ1-2.

Embodiment 2-1

[0047] Mix 18.5g of diammonium hydrogen phosphate, 108g of hydrogen-type multi-porous ZSM-5 molecular sieve and 120g of deionized water into a slurry, keep it at 70 °C for 2 hours, dry it in an oven at 110 °C, and bake it in air at 550 °C The phosphorus-containing ZSM-5 molecular sieve obtained for 2 hours; 2.1 g of cobalt nitrate was dissolved in 60 g of deionized water again, and the obtained phosphorus-containing ZSM-5 molecular sieve sample was mixed with the obtained phosphorus-containing ZSM-5 molecular sieve sample by dipping method for modification. After calcination for 2 hours, the obtained phosphorus and cobalt modified hierarchical porous ZSM-5 molecular sieve sample is denoted as GPZ2-1.

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Abstract

The modified MFI structure silicon-aluminum molecular sieve contains phosphorus and metal, the molar ratio of phosphorus (in terms of P2O5) to aluminum oxide is greater than or equal to 0.01, and the metal (in terms of oxide) accounts for 0.1-10 wt%; the K value of the molecular sieve is more than or equal to 70% and less than or equal to 90%, K is equal to P1 / P2 * 100%, P1 represents the mass percentage content of phosphorus in a 100-square-nanometer area within the vertical depth of 0-2nm of any crystal face of molecular sieve crystal grains measured by an XPS method, P2 represents the mass percentage content of phosphorus in the 100-square-nanometer area, and P2 represents the mass percentage content of phosphorus in the 100-square-nanometer area. P2 represents the mass percentage content of phosphorus in the area of a 100-square-nanometer area in a thickness interval of 5-10nm of the vertical depth of any crystal face of the molecular sieve crystal grain, which is measured by adopting an EPMA (Ethylene Propyl Methacrylate) method. The hydrothermal stability of the molecular sieve is improved by promoting coordination of phosphorus species and framework aluminum.

Description

technical field [0001] The present invention relates to a modified molecular sieve and a preparation method thereof, and furthermore, the present invention relates to a phosphorus and metal modified MFI structure silicon-alumina molecular sieve and a preparation method thereof. Background technique [0002] A typical representative of molecular sieves with MFI framework structure is ZSM-5 molecular sieve, which is a widely used catalytic material developed by Mobil Corporation of the United States in 1972. ZSM-5 molecular sieve has a three-dimensional crossed channel structure. The channels along the a-axis are straight pores, and the cross-sectional size is 0.54×0.56nm, which is approximately circular. The channels along the b-axis are Z-shaped pores, and the cross-sectional size is 0.51 ×0.56nm, elliptical. The pore of ZSM-5 molecular sieve is composed of ten-membered rings, and its size is between the small pore zeolite and the large pore zeolite, so it has a unique shap...

Claims

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Application Information

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IPC IPC(8): B01J29/46C10G11/05
CPCB01J29/46C10G11/05B01J2229/186C10G2300/1081C10G2400/20C10G2400/26C10G2300/1088Y02P20/52
Inventor 罗一斌王成强欧阳颖邢恩会舒兴田
Owner CHINA PETROLEUM & CHEM CORP