JP5793964B2 - Phosphorus modified zeolite catalyst - Google Patents

Description

  The present invention relates to a phosphorus-modified zeolite catalyst and a method for converting ethanol into propylene using the catalyst.

  Propylene is used in large quantities as a raw material for the synthesis of acrolein, acrylonitrile, isopropyl alcohol, acetone, glycerin, cumene, propylene oxide, allyl alcohol, and the like. In addition, polypropylene obtained by polymerizing propylene is used in a wide range of fields such as building materials and food containers.

  Many methods for producing propylene have been conventionally known, and methods for producing propylene from ethanol or ethylene using a catalyst have been reported. For example, Patent Document 1 discloses a method of converting n-butane to ethylene and propylene using a crystalline aluminosilicate containing a rare earth element. Patent Document 2 discloses a method of converting n-hexane into ethylene and propylene using a crystalline aluminosilicate carrying an alkaline earth metal, a rare earth element, and phosphorus.

JP 11-253807 A JP 2010-104878 A

  Many catalysts for producing propylene from ethanol and ethylene are known, but the production efficiency of propylene is still not sufficient. For example, when the ZSM-5 type zeolite catalyst in which lanthanum and phosphorus are sequentially supported in Patent Document 1 is used, the n-butane conversion is 93.7%, the ethylene yield is 28.1%, and the propylene yield is 20.9% (Example 5). The amount of the catalyst with respect to the supply amount of n-butane is 0.178 g · cc-butane / min. From this value and the propylene yield, the amount of propylene produced per unit time and unit time (STY) is 174 g- propylene / kg-cat / h. This production efficiency is difficult to use in industrial processes. In addition, since the n-butane concentration in the supply gas is as low as 13.4%, the cost of separation and purification of gas components unrelated to the reaction increases.

  In addition, when a ZSM-5 type zeolite catalyst supporting magnesium or calcium, lanthanum, and phosphorus in Patent Document 2 is used, the n-hexane conversion is about 95%, and the ethylene + propylene yield is about 55. % (Examples 1 to 4). The STY of propylene is only 1043 g-propylene / kg-cat / h even if it is highly estimated. In addition, since the n-hexane concentration in the supply gas is as low as 27%, the cost of separation and purification of gas components unrelated to the reaction increases.

  In both Patent Documents 1 and 2, the amount of catalyst is larger than the amount of raw material supplied, and the concentration of gas components other than the raw material is high. For this reason, it is difficult to industrially use the catalyst disclosed in the patent document. Moreover, in order to utilize industrially, it is necessary to supply a raw material by high concentration, However, In that case, generally a raw material conversion rate will fall.

  Therefore, an object of this invention is to provide the catalyst which can convert a high concentration raw material efficiently and selectively.

  As a result of intensive studies by the present inventors, it has been found that the above-mentioned problems can be solved by modifying the zeolite catalyst with phosphorus and adjusting the acid amount of the catalyst within a certain range.

That is, the present invention includes the following.
(1) A phosphorus-modified zeolite catalyst for converting ethanol into propylene having an acid amount of 0.4 to 0.7 mmol / g-cat.
(2) The phosphorus-modified zeolite catalyst according to (1), wherein the acid amount is 0.45 to 0.65 mmol / g-cat.
(3) The phosphorus-modified zeolite catalyst according to (2), wherein the acid amount is 0.6 to 0.65 mmol / g-cat.
(4) A method for producing propylene, comprising bringing ethanol into contact with the phosphorus-modified zeolite catalyst according to any one of (1) to (3).
(5) The method according to (4), wherein ethanol is supplied as a mixed gas having an ethanol concentration of 90% or more.

  According to the present invention, ethanol as a raw material can be efficiently and selectively converted into propylene.

The relationship between an acid amount and a propylene yield is shown.

Hereinafter, the present invention will be described in detail.
1. Phosphorus-modified zeolite catalyst In the present invention, the “phosphorus-modified zeolite catalyst” is a zeolite catalyst modified with phosphorus.

  The zeolite catalyst before modification with phosphorus is not particularly limited, and a general zeolite catalyst can be used. For example, MFI type zeolite catalyst, MEL type zeolite catalyst, FER type zeolite catalyst, MOR type zeolite catalyst, CHA type zeolite catalyst, TON type zeolite catalyst and the like can be mentioned. Although not particularly limited, it is preferable to use an MFI type zeolite catalyst, and it is particularly preferable to use a ZSM-5 type zeolite catalyst.

The ratio of Si and Al in the zeolite catalyst is not particularly limited. However, from the viewpoint of maintaining the activity of the catalyst, the SiO ₂ / Al ₂ O ₃ (molar ratio) is preferably 20 to 1000, preferably 30 to 400. It is particularly preferred. SiO ₂ / Al ₂ O ₃ (molar ratio) can be measured using a known method. For example, a method in which a zeolite catalyst is dissolved in an alkaline aqueous solution and analyzed by plasma emission spectroscopy can be used.

  The pore diameter of the zeolite catalyst is not particularly limited, but is preferably 0.2 to 1.2 nm and particularly preferably 0.3 to 0.7 nm from the viewpoint of improving reactivity and propylene selectivity.

  The phosphorus compound used for modifying the zeolite catalyst with phosphorus is not particularly limited as long as it contains phosphorus, and any of inorganic phosphorus compounds and organic phosphorus compounds can be used. In particular, inorganic phosphates are preferred, for example, primary sodium phosphate, secondary sodium phosphate, tertiary sodium phosphate, sodium pyrophosphate, primary potassium phosphate, secondary potassium phosphate, tertiary potassium phosphate. , Potassium pyrophosphate, monobasic ammonium phosphate, dibasic ammonium phosphate, tribasic ammonium phosphate, dibasic ammonium phosphate, dihydrogen ammonium phosphate, triammonium phosphate, tribasic calcium phosphate, monobasic calcium phosphate, Examples thereof include sodium pyrophosphate hydrogen, potassium hydrogen pyrophosphate, ammonium pyrophosphate, sodium metaphosphate, and ammonium metaphosphate. A phosphorus compound may be used independently and may be used in combination of 2 or more type.

  In the present invention, “modification” means that phosphorus is supported on the surface of the zeolite catalyst, or that phosphorus is contained in the pores of the zeolite catalyst, and that phosphorus is incorporated into the zeolite skeleton. It doesn't mean that. Phosphorus and the zeolite catalyst may simply be in contact with each other or may form a chemical bond. The method for modifying phosphorus to a zeolite catalyst is not particularly limited, and examples thereof include various known methods such as an ion exchange method, an impregnation method, and a hydrothermal synthesis method. For example, the zeolite catalyst can be modified with phosphorus by evaporating water after mixing an aqueous solution of a phosphorus compound and a zeolite catalyst.

  The acid amount of the catalyst can be adjusted by modifying the zeolite catalyst with phosphorus. The acid amount of the zeolite catalyst decreases as the amount of phosphorus modification increases. The acid amount of the phosphorus-modified zeolite catalyst of the present invention is 0.4 to 0.7 mmol / g-cat, preferably 0.45 to 0.65 mmol / g-cat, particularly preferably 0.6 to 0.65 mmol / g-cat. When the zeolite catalyst is modified with phosphorus and has an acid amount within the above range, ethanol can be efficiently and selectively converted to propylene.

Various known methods can be used as a method for measuring the acid amount. In the present invention, the acid amount is measured by an ammonia temperature-programmed desorption method (NH ₃ -TPD). The measurement conditions in NH ₃ -TPD employ the conditions described in the following examples.

2. Propylene Production Process The present invention also relates to a process for producing propylene by contacting ethanol with a phosphorus-modified zeolite catalyst.

  Ethanol may be supplied as it is or as a mixed gas with a dilution gas. The diluting gas is not particularly limited as long as it exists in a gaseous state under the condition that ethanol is present in a gaseous state and does not adversely affect the conversion of ethanol to propylene. For example, an inert gas such as nitrogen or argon can be used. However, for industrial use, it is preferable to use ethanol at a high concentration. For example, the ethanol concentration (molar ratio) is preferably 50% or more, more preferably 70% or more, further preferably 90% or more, and particularly preferably 95% or more.

The feeding rate of ethanol can be determined based on the activity of the catalyst used. Since the phosphorus-modified zeolite catalyst of the present invention can efficiently convert ethanol into propylene, the contact time (W / F) between ethanol and the catalyst is, for example, 0.01 to 10 g-cat · h · mol ^−. it can be ^1, and preferably, to ^{0.05~5g-cat · h · mol -1} , particularly preferably be a ^{0.1~1g-cat · h · mol -1} .

  Although reaction temperature will not be specifically limited if ethanol is efficiently and selectively converted into propylene, for example, 300-700 degreeC is preferable and 400-600 degreeC is especially preferable.

  The conversion from ethanol to propylene can be confirmed by analyzing the product gas by gas chromatography.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example and a comparative example, the technical scope of this invention is not limited to this.

Example 1
0.056 g of diammonium hydrogen phosphate (Nacalai Tesque, 99%) was dissolved in 20 ml of water. 5 g of NH ₄ —ZSM-5 type zeolite catalyst (manufactured by Tosoh Corporation, SiO ₂ / Al ₂ O ₃ molar ratio 40) was added to the aqueous solution and stirred at 80 ° C. for 1 hour. Thereafter, water was evaporated over 1 hour and dried at 105 ° C. for 6 hours to obtain a phosphorus-modified zeolite catalyst.

Using BELCAT-A manufactured by acid amount evaluation Nippon Bell Co., measured NH ₃ Atsushi Nobori behavior of the catalyst of _(NH 3 -TPD).
1) The catalyst is calcined at 550 ° C. for 30 minutes in a He stream, and then cooled to 100 ° C .;
2) Supply a mixed gas of 1% NH ₃ and 99% He to the catalyst at a flow rate of 100 ml / min for 10 minutes;
3) Supply water vapor by He gas bubbling for 60 minutes to remove NH ₃ adsorbed at other than acid sites;
4) Purge He gas at 100 ml / min for 30 minutes;
5) Increase the temperature from 100 ° C. to 600 ° C. at 10 ° C./min.

  The gas generated during the temperature increase in 5) was analyzed with a quadrupole mass spectrometer. The amount of acid was determined from the peak area above the line connecting the point at the start of temperature-programmed desorption gas analysis and the point at the completion of temperature-raising.

Ethanol conversion activity evaluation The ethanol catalytic cracking reaction of the catalyst was measured using a fixed bed flow reactor. The total flow rate (278 ml) of vaporized ethanol + nitrogen mixed gas (EtOH: N ₂ = 50: 50) was added to 0.5 g of catalyst so that W / F was 0.67 g-cat · h · mol ^−1. Contact was made at 500 ° C. The produced gas was analyzed by gas chromatography.

Example 2
The same operation as in Example 1 was carried out except that 0.138 g of diammonium hydrogen phosphate was used.

Example 3
The same operation as in Example 1 was performed except that 0.2165 g of diammonium hydrogen phosphate was used.

Example 4
The same operation as in Example 1 was performed except that 0.275 g of diammonium hydrogen phosphate was used.

Example 5
The same operation as in Example 1 was performed except that 0.407 g of diammonium hydrogen phosphate was used.

Comparative Example 1
The same operation as in Example 1 was performed except that the catalyst was not modified with phosphorus.

Example 6
In the ethanol conversion activity evaluation, the same operation as in Example 1 was performed except that the ratio of vaporized ethanol + nitrogen mixed gas was EtOH: N ₂ = 95: 5.

Example 7
In the ethanol conversion activity evaluation, the same operation as in Example 2 was performed except that the ratio of vaporized ethanol + nitrogen mixed gas was EtOH: N ₂ = 95: 5.

Example 8
In the ethanol conversion activity evaluation, the same operation as in Example 3 was performed except that the ratio of vaporized ethanol + nitrogen mixed gas was EtOH: N ₂ = 95: 5.

Example 9
In the ethanol conversion activity evaluation, the same operation as in Example 4 was performed except that the ratio of vaporized ethanol + nitrogen mixed gas was EtOH: N ₂ = 95: 5.

Example 10
In the ethanol conversion activity evaluation, the same operation as in Example 5 was performed except that the ratio of vaporized ethanol + nitrogen mixed gas was EtOH: N ₂ = 95: 5.

Comparative Example 2
In the ethanol conversion activity evaluation, the same operation as in Comparative Example 1 was performed except that the ratio of vaporized ethanol + nitrogen mixed gas was EtOH: N ₂ = 95: 5.

  The acid amounts of the phosphorus-modified zeolite catalyst obtained in Examples 1 to 5 and the zeolite catalyst of Comparative Example 1 are shown in Table 1. (The acid amounts in Examples 6 to 10 and Comparative Example 2 are the same as in Examples 1 to 5, respectively. And the acid amount in Comparative Example 1).

  The carbon yield of each product gas analyzed in Examples 1 to 5 and Comparative Example 1 is shown in Table 2, and the carbon yield of each product gas analyzed in Examples 6 to 10 and Comparative Example 2 is shown in Table 3. Moreover, the relationship between the acid amount and propylene yield in each Example and each Comparative Example is shown in FIG.

The carbon yield was calculated by the following formula.
Carbon yield (%) = [number of moles of product gas × number of carbons per mole of each component / (number of moles of supplied ethanol × 2)] × 100

  Table 4 shows STY in each example and each comparative example.

  By modifying the zeolite catalyst with phosphorus and adjusting the acid amount within a certain range, the STY was greatly improved as compared with the zeolite catalyst not modified with phosphorus. In particular, when the ethanol concentration in Example 6 was 95%, an extremely high STY of 9618 g-propylene / kg-cat / h was obtained.

Claims (3)

A phosphorus-modified zeolite catalyst for converting ethanol into propylene having an acid amount of 0.45 to 0.65 mmol / g-cat. Acid amount is 0.6~0.65mmol / g-cat, phosphorus-modified zeolite catalyst of claim 1. Comprising contacting the phosphorus-modified zeolite catalyst according 90% ethanol concentration in claim 1 or 2, the production method of propylene.

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