JPH02184638A - Production of lower olefin composed mainly of propylene - Google Patents

Abstract

PURPOSE:To obtain the subject substance in high selectivity and conversion by contacting hydrocarbons composed mainly of 3-10C paraffins with a crystalline aluminosilicate zeolite catalyst supporting a specific amount of silver or further phosphorus. CONSTITUTION:The subject substance can be produced in high yield by contacting hydrocarbons composed mainly of 3-10C paraffins with a specific crystalline aluminosilicate zeolite catalyst at 450-600 deg.C. The above catalyst is produced preferably by supporting 0.1-50wt.% of silver, or further 0.1-5.0wt.% of phosphorus on a ZSM-5 zeolite having an SiO2/Al2O3 molar ratio of >=25. The addition of phosphorus is effective in suppressing the deposition of coke without deteriorating the characteristic properties of silver and in improving the stability of the catalyst to hot steam.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for the catalytic conversion of hydrocarbons mainly consisting of paraffins. More specifically, by using crystalline aluminosilicate zeolite supporting silver or silver and phosphorus as a catalyst, hydrocarbons mainly composed of paraffins can be efficiently converted into propylene, which is valuable as a petrochemical raw material, as the main component. The present invention relates to a method for producing lower olefins.

(Prior Art) It is well known that various hydrocarbon raw materials are brought into contact with a solid acid catalyst, especially crystalline aluminosilicate zeolite, and converted using reactions such as cracking, isomerization, disproportionation, and hydrocracking. It is being

Typically, Y-type zeolite is used to convert heavy oil and the like into gasoline fractions, which is widely practiced in petroleum refining. Furthermore, in recent years, methods have been proposed for converting light petroleum fractions into lower olefins using various proton type zeolites.

For example, JP-A-51-57688, JP-A-60-
There are publications such as No. 178830. Also, vol. 28 of the Journal of the Japan Petroleum Society.

No. 3 (1985) "Catalytic Cracking of Hydrocarbons Using Zeolite Catalysts" Various zeolite catalysts were used for the catalytic cracking of loopentane, and their properties as shape-selective catalysts were extensively elucidated.

Furthermore, JP-A-59-148728, JP-A-59-148728,
-152334 publication and JP-A-82-285987
The publication describes that olefins of 02 to C1 are also produced as by-products when aliphatic hydrocarbons are converted to aromatic hydrocarbons using a metal-supported zeolite catalyst.

(Problems to be Solved by the Invention) In recent years, in Japan, where demand for propylene and lower olefins mainly composed of propylene as resin raw materials has been increasing, the production of these products is mainly based on by-products from ethylene plants resulting from the thermal decomposition of naphtha, Alternatively, they rely on by-products from FCC brands to obtain catalytic cracking gasoline, but since they are by-products, they cannot be expected to obtain high yields and are limited to low yields, so the demand for the main product is increasing. If it did not stretch, there would be a shortage of propylene and lower olefins mainly composed of propylene. Therefore, a method for efficiently producing lower olefins containing propylene as a main component is desired, but none of the known methods is satisfactory.

For example, in the catalytic conversion method using Y type zeolite, ferrierite, and mordenite, lower paraffins such as methane, ethane, and propane are mainly produced, and in the method using ZSM-5 type zeolite, methane, ethane, propane, etc. Low grade paraffin.

and aromatic hydrocarbons are mainly produced. Furthermore, methods for producing aromatic hydrocarbons using zeolite carrying metal oxides or carrying out ion exchange treatment with metal ions (JP-A-59-148728, JP-A-59-1999)
152334 and JP-A-62285987), aromatic hydrocarbons are the main product, and although olefins are also produced as by-products, the selectivity of aromatic hydrocarbons is relatively low and the by-product rate of olefins is relatively low. When it is relatively high, the conversion rate tends to decrease. In this way, the problem could not be solved by any of the methods.

The present invention solves these problems by producing lower olefins mainly consisting of propylene in high yields, that is, with high selectivity and high conversion rate, by catalytic reaction of hydrocarbons mainly consisting of paraffins. The purpose is to

(Means for Solving the Problems) As a result of intensive studies to achieve the above object, the present inventors have determined that a specific metal can be used in a catalytic reaction of a hydrocarbon raw material f1 mainly consisting of paraffin. When the reaction is carried out using supported crystalline aluminosiliphyte zeolite as a catalyst and the reaction is carried out within a specific contact time, the formation of paraffins and aromatic hydrocarbons is surprisingly suppressed, and the desired propylene is converted into a main component. It has been found that lower olefins can be obtained in high yield, that is, with high selectivity and high conversion.

That is, the present invention provides a method for producing a lower olefin mainly composed of propylene by a catalytic reaction of hydrocarbons mainly composed of paraffins having 3 to 10 carbon atoms.
The catalyst is a crystalline aluminosilicate zeolite carrying % by weight of silver, and the contact time between the raw fiI paraffin and the catalyst is 1.0 seconds or less, or the crystalline aluminosilicate zeolite carrying silver is further 0.1 ~5
．． The present invention relates to a method for producing a lower olefin mainly composed of propylene, which is characterized by supporting 0% by weight of phosphorus.

More specifically, the hydrocarbon used as a raw material in the catalytic reaction of the present invention is a paraffin having 3 to 10 carbon atoms or a hydrocarbon containing the paraffin as a main component. Specifically, propane, n-butane, i-butane, rhopentane, 1-pentane, 11-hexane, i-
Paraffins such as hexane, heptane, octane, nonane, and decane, and naphthas mainly composed of mixtures thereof, with a carbon number of 4 or more and a boiling point of 150° C. or less are preferred.

The crystalline aluminosilicate zeolite, which is one of the constituent elements of the catalyst used in the present invention, includes X-type zeolite, Y-type zeolite, mordenite, ferrierite,
Examples include offretite, erionite, zeolite containing a mixture of offretite and erionite structures, ZSM-5 type zeolite, and hydrogen ion compounds thereof.

Particularly preferred is S i O2/ A l
20 ZSM with a molar ratio (hereinafter referred to as molar ratio) of 25 or more
Examples include -5 type zeolite and zeolite with a mixture of offretite and erionite structures. When using ZSM-5 type zeolite, the reaction product depends on the SiO□/Al a Os ratio in the crystal structure, and S
i O2 / A lx When the O3 ratio is small, the activity is high, so although the conversion rate is high, the selectivity for lower paraffins and aromatic hydrocarbons such as methane, ethane, and propane is high, and the selectivity for lower olefins such as propylene is low. .

On the other hand, when the S io 2/A IhO3 ratio increases, the conversion rate decreases due to low activity. Therefore, in the present invention, ZSM-5 type zeolite (hereinafter referred to as 823M-5 zeolite), which is obtained by converting ZSM-5 type zeolite (hereinafter referred to as NaZSM 5 type zeolite) in a cationic state with Nu, into a hydrogen ion type zeolite (hereinafter referred to as 823M-
When using type 5 zeolite), S i O2
/ A Ib Os ratio is preferably 25-800, more preferably 35-600.

In general, when the amount of metal supported on crystalline aluminosilicate zeolite is small, lower paraffins such as ethane and propane tend to form, whereas when the amount of metal supported is large, methane and aromatic hydrocarbons tend to be mainly produced. There is.

Therefore, in order to produce a large amount of lower olefin mainly composed of propylene, which is the object of the present invention, it is important to adjust the amount of metal supported I.

In the method of the present invention, the metal supported on the zeolite is silver. Silver loading I on zeolite is 0.1~
50% by weight, preferably 0.2-20% by weight. The contact time between the raw material hydrocarbon and the catalyst is usually 1.0 seconds or less.

Even when the reaction is carried out under conditions slightly outside the ranges of support I and contact time described above, the yield of lower olefins containing propylene as a main component does not decrease so much, but the excellent effects of the present invention, namely, It is difficult to maintain high yields above 50°6.

Silver can be supported by commonly used methods such as an ion exchange method, an impregnation method, and a kneading method. The metal salts used include commonly available ones, such as silver nitrate, silver acetate, and silver sulfate. The crystalline aluminosilicate zeolite that has been subjected to silver-supporting treatment can be calcined by a commonly used method. Firing temperature is 300-800
℃, preferably 400-650℃, baking time 0.1-650℃
20 hours, preferably 0.5 to 10 hours.

It should be noted that all of the above supported amounts of silver are values calculated as metal.

Furthermore, when crystalline aluminosilicate zeolite supports phosphorus in addition to the above-mentioned silver, it is possible to suppress the formation of coke without impairing the properties of the above-mentioned silver, and the stability against high-temperature steam is improved. . The supported amount of phosphorus, which has such an effect, is within the range of 0.1 to 5.0% by weight as an element.

The phosphorus may be supported before or after silver is supported on the crystalline aluminosilicate zeolite, and the method of supporting phosphorus is the same as that for silver. The phosphorus compounds used are preferably phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate and their respective water-soluble phosphates.

The crystalline aluminosilicate zeolite may also be used in combination with porous materials such as alumina, silica, diatomaceous earth, clay, zirconia, titania, silica-alumina, silica-magnesia, silica-zirconia, silica-titania, etc. In this case, the mixing treatment may be performed either before or after the silver is supported.

The reaction temperature in the method of the present invention is 350 to 700°C, preferably 400 to 650°C, more preferably 450 to 600°C.
If the reaction temperature does not reach 350°C, the conversion SS of the raw material paraffin will be low, and if it exceeds 700°C, a large amount of methane and aromatic hydrocarbons will be generated, and the production of coke will increase rapidly, which is not preferable.

The method of the present invention does not require a fixed bed type, a fluidized bed type, or a gas flow conveyance type, and the gas flow for conveyance may be, for example, carbon dioxide, helium, nitrogen, steam, or smoke substantially free of oxygen. It is preferable to use road gas or the like.

(Effects of the Invention) In the method of the present invention, by using crystalline aluminosilicate zeolite as a catalyst and supporting silver in a specific ratio, the production of lower paraffins and aromatic hydrocarbons is suppressed and propylene is the main component. The selectivity of lower olefins can be significantly increased to 55-80% by weight, and the conversion rate of raw material C1-CIO paraffin can always be increased to over 70%, so the yield of lower olefins containing propylene as the main component can be increased. It can be 50% or more.

In addition, when using a catalyst that supports phosphorus along with silver, coke formation is suppressed and stability against high temperature steam is improved compared to when a catalyst that does not support phosphorus is used. The life of these catalysts will not be shortened even if they contain moisture, when the catalyst is regenerated with the generation of steam, or when high-temperature steam is used as a carrier air stream. Lower olefins containing propylene as a main component can be produced economically.

(Examples) The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited by these.

Example I 823M-5 type zeolite (S! 02/A 12
0 x = 200) was immersed in a 15% by weight silver nitrate solution, dried, and calcined in air at 550°C for 5 hours to remove 3% silver.
．． 0 weight I pa. The supported catalyst was prepared.

A quartz reaction tube (inner diameter 4 flexible pot φ) was filled with 3 cc (200 zy) of 24 to 32 mesh particles and heated at 600 ''C for 1 hour under air circulation. Under gas flow (5000z1/hr
, NTP (the same applies hereafter) to 550''C, 1 μr of n-hexane was injected and the contact time was 0.0
A contact reaction was carried out in 7 seconds. The reaction product was analyzed using a gas chromatograph. The results are shown in Table 1 along with the results of Example 2.3 and Comparative Example 1 below.

Example 2 823M-5 type zeolite (Sio2/AI2
03”200) using 0.1N ILQ silver acid solution
The treatment was carried out for 50 hours at a temperature of 0°C. After washing with water and drying, the catalyst was calcined in air at 550°C for 15 hours to prepare a catalyst. The catalyst carried 1.6% by weight of silver. A catalytic reaction was carried out under the same conditions as in Example 1 using this catalyst.

Example 3 A catalytic reaction was carried out under the same conditions as in Example 1, except that the amount of silver supported was changed to 0.2% by weight.

Comparative Example 1 A catalytic reaction was carried out under the same conditions as in Example 1 using the zeolite used in Example 1 as a catalyst without supporting silver.

Example 4 HZ SM-5 type 5th A) (SSOz/AI
! , 0a=50)! A contact reaction was carried out under the same conditions as in Example 1 except that 5.0% by weight of silver was supported and the reaction temperature was changed to 500'C.

The results are shown in Table 2 together with the results of Example 5 and Comparative Example 2.

Example 5 A contact reaction was carried out under the same conditions as in Example 4, except that the amount of silver supported was changed to 20.0% by weight.

Comparative Example 2 A catalytic reaction was carried out under the same conditions as in Example 4 using the zeolite used in Example 4 as a catalyst without supporting silver.

Table Example 6 Zeolite mixed with off-retite erionite (manufactured by Tosoh Corporation, S i O! / AI 103 = 8
A catalytic reaction was carried out under the same conditions as in Example 1 using 5.0% by weight of silver supported on the hydrogen ion form of , 0) as a catalyst. The results are shown in Table 3 together with the results of Comparative Example 3.

Comparative Example 3 A catalytic reaction was carried out under the same conditions as in Example 1 using the zeolite used in Example 6 as a catalyst without supporting silver.

Example 7 HY type zeolite) (Sloz/ALOa=4.8) and silica-alumina (38% AI 20 s/62% Si
O□) were mixed in a ratio of 20 to 80, and silver was 3.0% by weight.
A catalytic reaction was carried out under the same conditions as in Example 1, except that the supported material was used as a catalyst and the reaction temperature was changed to 600°C. The results are shown in Table 3 together with the results of Comparative Example 4.

Comparative Example 4 A catalytic reaction was carried out under the same conditions as in Example 7 using the zeolite used in Example 7 as a catalyst without supporting silver.

Table 1 Example 8 A catalytic reaction was carried out under the same conditions as in Example 1, except that the raw material hydrocarbon was changed to rhopentane and the amount of silver supported on the catalyst was changed to 1% by weight. The results are shown in Table 4 along with the results of Examples 9 and 10 below.

Example 9 A catalytic reaction was carried out under the same conditions as in Example 1, except that n-hebutane was used as the raw material hydrocarbon.

Example 1O Contact was carried out under the same conditions as in Example 1, except that the hydrocarbon in the raw fl was changed to naphtha (specific gravity 0.700, composition: paraffin 81 weight 06, naphthene 12 weight 1%, aromatic hydrocarbon 7 weight %). The reaction was carried out.

In addition, the conversion rate and paraffin and aromatics in the product distribution were determined as follows. When calculating the conversion rate, C1 to C present in the raw material naphtha.

Ignoring paraffin since it is a small amount, the composition of the gas flowing out from the reactor was analyzed, and all of the existing C1 or higher paraffins and naphthenes (16.8%) were treated as a final fraction, and they were found to be present in the reactor effluent. Aromatic (18,0%) is the original
Since the amount was larger than the amount present in the raw material, 7% present in the raw material was directly converted into a raw material, and a total of 23.8% was taken as an unconverted rate. Therefore, the conversion rate is 76.2%. Therefore, the paraffins in the zero-order product distribution are based on the system excluding the above-mentioned fractions from the reactor effluent, and the C to C paraffins contained therein. It is quantity. As mentioned above, the amount of aromatics produced by this reaction (11.0% of the aromatics in the reactor effluent excluding 70% of unconverted aromatics) is distributed in the product. 0762 to convert
It was calculated by dividing by

Table 4 Example 11 ) IZSM-5 type zeolite t・(Sio2/Al2O.

=50) was immersed in diammonium hydrogen phosphate solution with S weight j1%? The wheat was dried and calcined in air at 550° C. for 5 hours to support 1.0% by weight of phosphorus. This was mixed with 5.0% by weight of silver under the same conditions as in Example 1.
The grains were sorted into mensch and packed into a stainless steel reaction tube to examine their stability against steam.
I did a steam treatment for 25 hours at a temperature of 00'C.
A contact reaction was carried out under the same conditions as in Example 1. The results are shown in the fifth column.2 Comparative Example 4 HZ SM-5 type zeolite) (Si02.'A/2
0)=50) was subjected to steam treatment under the same conditions as in Example 13, and then subjected to a contact reaction. The results are shown in Table 5.

Claims (2)

[Claims] (1) Crystalline aluminosilicate carrying 0.1 to 50% by weight of silver for producing lower olefins mainly composed of propylene by catalytic reaction of hydrocarbons mainly consisting of paraffins having 3 to 10 carbon atoms. A method for producing lower olefins containing propylene as a main component, characterized by using zeolite as a catalyst. (2) The method for producing a lower olefin containing propylene as a main component according to claim 1, wherein the crystalline aluminosilicate zeolite catalyst further supports 0.1 to 5.0% by weight of phosphorus.