Boron-containing molecular sieve cha

Abstract

A boron-containing molecular sieve having the CHA crystal structure and comprising (1) silicon oxide and (2) boron oxide or a combination of boron oxide and aluminum oxide, iron oxide, titanium oxide, gallium oxide and mixtures thereof is prepared using a quaternary ammonium cation derived from 1-adamantamine, 3-quinuclidinol or 2-exo-aminonorbornane as structure directing agent. The molecular sieve can be used for gas separation or in catalysts to prepare methylamine or dimethylamine, to convert oxygenates (e.g., methanol) to light olefins, or for the reduction of oxides of nitrogen n a gas stream (e.g., automotive exhaust) and to reduce cold start emissions from engines.

Description

Background of the invention

[0001] The crystal structure of chabazite known as "CHA" is an approximate molecular formula of Ca 6 al 12 Si 24 o 72 natural zeolite. Synthetic forms of chabazite are described by D. W. Breck in Zeolite Molecular Sieves, John Wiley & Sons, 1973. The various synthetic forms reported by Breck are: zeolite "K-G" described by Barrer et al. in J.Chem.Soc., p.2822 (1956); zeolite D disclosed in BP 868846 (1961) and April 17, 1962 Zeolite R disclosed in US 3030181 to Milton et al. Chabazite is also discussed in W.H. Meier and D.H. Olson, "Atlas of Zeolite Structure Types" (1978).

[0002] The K-G zeolite reported by Barrer et al. in J. Chem. Soc. is a potassium zeolite having a silica:alumina molar ratio (referred to herein as "SAR") of 2.3:1 to 4.15:1. Zeolite D reported in BP868846 is a sodium-potassium zeolite with a SAR of 4.5:1 to 4.9:1. Zeolite R reported in US3030181 is a sodium zeolite with a SAR of 3.45:1 to 3.65:1.

[0003] Abstract ent...

Examples

Embodiment 1-14

[0181] Boron-containing CHA was synthesized by preparing a gel composition (ie, reaction mixture) having the composition of the molar ratios listed in the table below. The resulting gel was placed in a Parr bomb reactor and heated in an oven at the temperature described below while rotating at the speed described below. The product was analyzed by X-ray diffraction (XRD), and it was found that the product was a boron-containing molecular sieve with a CHA structure. The source of silica was Cabosil M-5 fumed silica or HiSil 233 amorphous silica (0.208 wt% alumina). The boron oxide source was boric acid and the alumina source was Reheis F 2000 alumina.

[0182] Example

SiO 2 / B 2 o 3

SiO 2 / Al 2 o 3

h 2 O / SiO 2

Oh - / SiO 2

Na + / SiO 2

SDA / SiO2 2

Reaction conditions 1

seed crystal

%

1-ada 2

1

2.51

1010

23.51

0.25

0.20

0.25

140 / 43 / 5d ...

Embodiment 15-20

[0186] Deboronation

[0187] Boron was removed from the molecular sieve samples prepared in Example 13 above and then calcined. The samples were heated in acidic solution under the conditions listed in the table below. The results are listed in the table.

[0188] Initially

Background of the invention

[0001] The crystal structure of chabazite known as "CHA" is an approximate molecular formula of Ca 6 al 12 Si 24 o 72 natural zeolite. Synthetic forms of chabazite are described by D. W. Breck in Zeolite Molecular Sieves, John Wiley & Sons, 1973. The various synthetic forms reported by Breck are: zeolite "K-G" described by Barrer et al. in J.Chem.Soc., p.2822 (1956); zeolite D disclosed in BP 868846 (1961) and April 17, 1962 Zeolite R disclosed in US 3030181 to Milton et al. Chabazite is also discussed in W.H. Meier and D.H. Olson, "Atlas of Zeolite Structure Types" (1978).

[0002] The K-G zeolite reported by Barrer et al. in J. Chem. Soc. is a potassium zeolite having a silica:alumina molar ratio (referred to herein as "SAR") of 2.3:1 to 4.15:1. Zeolite D reported in BP868846 is a sodium-potassium zeolite with a SAR of 4.5:1 to 4.9:1. Zeolite R reported in US3030181 is a sodium zeolite with a SAR of 3.45:1 to 3.65:1.

[0003] Abstract ent...

Examples

Embodiment 1-14

[0181] Boron-containing CHA was synthesized by preparing a gel composition (ie, reaction mixture) having the composition of the molar ratios listed in the table below. The resulting gel was placed in a Parr bomb reactor and heated in an oven at the temperature described below while rotating at the speed described below. The product was analyzed by X-ray diffraction (XRD), and it was found that the product was a boron-containing molecular sieve with a CHA structure. The source of silica was Cabosil M-5 fumed silica or HiSil 233 amorphous silica (0.208 wt% alumina). The boron oxide source was boric acid and the alumina source was Reheis F 2000 alumina.

[0182] Example

SiO 2 / B 2 o 3

SiO 2 / Al 2 o 3

h 2 O / SiO 2

Oh - / SiO 2

Na + / SiO 2

SDA / SiO2 2

Reaction conditions 1

seed crystal

%

1-ada 2

1

2.51

1010

23.51

0.25

0.20

0.25

140 / 43 / 5d ...

Embodiment 15-20

[0186] Deboronation

[0187] Boron was removed from the molecular sieve samples prepared in Example 13 above and then calcined. The samples were heated in acidic solution under the conditions listed in the table below. The results are listed in the table.

[0188] Initially

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