阅读说明：本技术 丙烷脱氢制丙烯的催化剂及其制备方法和应用 (Catalyst for preparing propylene by propane dehydrogenation and preparation method and application thereof ) 是由 张明森 张郁葱 刘红梅 冯静 于 2019-03-11 设计创作，主要内容包括：本发明提供了一种丙烷脱氢制丙烯的催化剂及其制备方法和应用,该催化剂包括：载体以及负载在载体上的活性组分,其中载体为微孔全硅分子筛,活性组分为第IIB族金属元素中的一种或多种。其制备方法包括：步骤S1、提供微孔全硅分子筛和活性组分的前驱体；步骤S2、将微孔全硅分子筛与活性组分的前驱体接触,然后进行干燥、焙烧、成型得到催化剂前体；步骤S3、还原所述催化剂前体得到所述催化剂。该催化剂用于丙烷脱氢反应中得到的丙烯的选择性高,丙烯的产率高。(The invention provides a catalyst for preparing propylene by propane dehydrogenation, a preparation method and an application thereof, wherein the catalyst comprises the following components: the carrier is a microporous all-silicon molecular sieve, and the active component is one or more of group IIB metal elements. The preparation method comprises the following steps: step S1, providing a microporous all-silicon molecular sieve and a precursor of an active component; step S2, contacting the microporous all-silicon molecular sieve with a precursor of an active component, and then drying, roasting and forming to obtain a catalyst precursor; and step S3, reducing the catalyst precursor to obtain the catalyst. The catalyst is used for propane dehydrogenation reaction to obtain propylene with high selectivity and high propylene yield.)

1. The catalyst for preparing propylene by propane dehydrogenation comprises a carrier and an active component loaded on the carrier, wherein the carrier is a microporous all-silicon molecular sieve; the active component is selected from one or more of group IIB metal elements, preferably Zn.

2. Catalyst according to claim 1, characterized in that the support is a molecular sieve of the MFI type, preferably a Silicate-1 molecular sieve.

3. The catalyst according to claim 1 or 2, characterized in that the active component is present in an amount of 0.01 to 20%, preferably 1 to 20%, more preferably 3 to 15%, based on the total weight of the catalyst.

4. The catalyst of any of claims 1 to 3, wherein the microporous all-silica molecular sieve has an average pore size ofPreferably, it is

5. The catalyst of any of claims 1 to 4, wherein the microporous all-silica molecular sieve is prepared by a method comprising the steps of:

mixing a silicon source and a template agent, and then carrying out crystallization, solid-liquid separation, washing, drying and roasting to obtain a microporous all-silicon molecular sieve; wherein the silicon source is SiO₂The molar ratio of the silicon source to the template agent is preferably 1: (0.05-1.0).

6. The catalyst according to claim 5,

the silicon source is organic silicate, preferably (OR)₁)₄Organosilicates of Si wherein R₁Is an alkyl group having 1 to 4 carbon atoms, more preferably tetraethyl silicate; and/or the presence of a gas in the gas,

the template agent is tetrapropylammonium hydroxide; and/or the presence of a gas in the gas,

the crystallization temperature is 120-180 ℃, and the crystallization time is 12-72 h.

7. A method of preparing the catalyst of any one of claims 1-6, comprising:

step S1, providing a microporous all-silicon molecular sieve and a precursor of an active component;

step S2, contacting the microporous all-silicon molecular sieve with a precursor of an active component, and then drying, roasting and forming to obtain a catalyst precursor;

and step S3, reducing the catalyst precursor to obtain the catalyst.

8. The method according to claim 7, wherein the precursor of the active component is one or more of a sulfate, a nitrate and an oxalate of the active component.

9. The method of claim 7 or 8, wherein in step S2, the microporous all-silica molecular sieve is contacted with the precursor of the active component by impregnating the all-silica molecular sieve with the precursor of the active component.

10. Use of a catalyst according to any one of claims 1 to 6 or a catalyst obtainable by a process according to any one of claims 7 to 9 in the dehydrogenation of propane to propene.

Technical Field

The invention relates to a catalyst for preparing propylene by propane dehydrogenation and a preparation method and application thereof.

Background

Polypropylene is a very important polymer in the automotive, textile, furniture, tubing and packaging industries. Propylene is the most important monomer for the production of polypropylene. In addition, propylene is also an important raw material for the synthesis of many other important chemical products, such as propylene oxide, acrylic acid, acrylonitrile, cumene, and alcohols.

The four major sources of propylene currently are: a catalytic cracking unit (accounting for about 35% of the propylene yield), an ethylene cracking unit (accounting for about 60% of the propylene yield), a propane dehydrogenation unit, and a methanol-to-olefin unit in the coal chemical industry. Among them, a propane dehydrogenation apparatus and a methanol-to-olefin apparatus in coal chemical industry are newly emerging routes for producing propylene. With the increase of the yield of the American shale gas, the byproduct ethane gradually becomes a main raw material of a steam cracking device, the main product of ethane cracking is ethylene, the amount of the byproduct propylene of the device is greatly reduced, and the supply of propylene is in a state of becoming tense day by day. The price of propane is decreasing, so that the production of propylene from propane is receiving more and more attention.

The propane dehydrogenation plant in current industrial production mainly employs the Oleflex process of UOP (american ring oil company) and the Catofin process of ABB Lummus (ABB Lummus company), both using platinum-based and chromium-based catalysts, respectively. However, both of these catalysts have the serious problems of high price and environmental pollution, so there is a need to develop a supported non-noble metal dehydrogenation catalyst which is low in price and environmentally friendly.

Disclosure of Invention

In order to solve the problems of high price and serious environmental pollution of the existing propane dehydrogenation catalyst, the invention provides a novel propane dehydrogenation propylene preparation catalyst, the catalyst takes non-noble metal as an active component, a microporous all-silicon molecular sieve is used as a carrier, and the provided catalyst has the catalytic activity and the propylene yield which are equivalent to or even higher than those of the existing chromium catalyst.

According to a first aspect of the present invention, there is provided a propane dehydrogenation catalyst comprising a carrier and an active component supported on the carrier, wherein the carrier is a microporous all-silica molecular sieve; the active component is one or more of group IIB elements.

According to a preferred embodiment of the invention, the carrier is a molecular sieve of the MFI type.

Preferably, the support is a Silicate-1 molecular sieve.

According to a preferred embodiment of the invention, the active component is zinc. The inventor of the application finds that when the active component is zinc and the carrier is a Silicate-1 molecular sieve, the obtained catalyst has a remarkably excellent effect compared with other catalysts.

According to a preferred embodiment of the present invention, the active component is present in an amount of 0.01 to 20%, for example 0.01%, 0.05%, 1%, 3%, 5%, 7%, 9%, 10%, 12%, 14%, 16%, 18%, 20% and any value therebetween, preferably 1 to 20%, more preferably 3 to 15%, based on the total weight of the catalyst. The content of the active component is herein based on the metal element.

According to a preferred embodiment of the present invention, the microporous all-silica molecular sieve has an average pore size ofFor example, can beAnd any value in between, preferably

And/or the specific surface area is 320-540m²A/g of, for example, 320m²/g、340m²/g、360m²/g、380m²/g、400m²/g、420m²/g、440m²/g、460m²/g、480m²/g、500m²/g、520m²/g、540m²G and itAny value in between, preferably 400-500m²In g, and/or a pore volume of 0.2 to 0.4cm³Per g, for example, may be 0.2cm³/g、0.22cm³/g、0.24cm³/g、0.26cm³/g、0.28cm³/g、0.30cm³/g、0.32cm³/g、0.34cm³/g、0.36cm³/g、0.38cm³/g、0.4cm³G and any value therebetween, preferably 0.22-0.32cm³/g。

According to a preferred embodiment of the present invention, the microporous all-silica molecular sieve is prepared by a method comprising the steps of:

mixing a silicon source and a template agent, and then stirring, crystallizing, carrying out solid-liquid separation, washing, drying and roasting to obtain the silicon-based composite material; wherein the silicon source is SiO₂The molar ratio of the silicon source to the template agent is preferably 1: (0.05-1.0), for example, 1:0.05, 1:0.1, 1:0.2, 1:0.4, 1:0.5, 1:0.6, 1:0.8, 1:1.0 and any value in between, preferably 1: (0.5-1.0).

According to a preferred embodiment of the invention, the silicon source is an organosilicate, preferably of the formula (OR)₁)₄Organosilicates of Si wherein R₁Alkyl groups having 1 to 4 carbon atoms (e.g., methyl, ethyl, n-propyl, isopropyl, butyl), more preferably tetraethyl silicate; and/or the presence of a gas in the gas,

preferably, the template agent is tetrapropylammonium hydroxide; and/or the presence of a gas in the gas,

the crystallization temperature is 120-180 ℃, and preferably is 120-160 ℃; the crystallization time is 12-72h, preferably 30-60 h.

The solid-liquid separation is carried out in a manner commonly used in the art, such as filtration or centrifugation.

And the washing is to wash the solid matter obtained by solid-liquid separation to be neutral.

The roasting is carried out at the temperature of 500-700 ℃, and the roasting time is 8-20 h.

According to another aspect of the present invention, there is provided a method for preparing the catalyst, which comprises:

step S1, providing a microporous all-silicon molecular sieve and a precursor of an active component;

step S2, contacting the microporous all-silicon molecular sieve with a precursor of an active component, and then drying, roasting and forming to obtain a catalyst precursor;

and step S3, reducing the catalyst precursor to obtain the catalyst.

According to a preferred embodiment of the present invention, the microporous all-silica molecular sieve is prepared using the synthesis method described above.

According to a preferred embodiment of the present invention, the microporous all-silica molecular sieve is contacted with the precursor of the active component in a manner that can be used in a manner commonly used in the art, such as by impregnation or precipitation. The impregnation can be the impregnation of the all-silicon molecular sieve with a solution of an active component precursor; the precipitation can be the solution or suspension of the precursor of the active component mixed with the microporous all-silicon molecular sieve, and then ammonia water is added to precipitate the precursor of the active component on the carrier.

According to a preferred embodiment of the present invention, in the preparation method of the catalyst, in step S2, the conditions for the drying and calcination are not particularly limited and may be those conventional in the art. The conditions for drying and calcining may be well known to those skilled in the art, for example, the drying temperature may be 50 to 120 ℃ and the drying time may be 4 to 10 hours; the roasting temperature is 300-600 ℃, and the roasting time is 3-8 h. Under the roasting condition, the precursor of the active component is converted into the oxide of the active component.

According to a preferred embodiment of the present invention, in the method for preparing the catalyst, the molding may be a tablet or an extrusion molding in step S2.

According to a preferred embodiment of the present invention, in the preparation method of the catalyst, in step S3, the valence state of the active component in the catalyst is modulated during the reduction process, so that the dehydrogenation reaction is more facilitated. Preferably, the reduction temperature is 300-600 ℃, and the reduction time is 0.5-2 h. The reduction of the catalyst precursor is carried out in a hydrogen-containing atmosphere, preferably, the hydrogen content of the hydrogen-containing atmosphere is 10 to 100%.

According to a preferred embodiment of the present invention, the reduction of the catalyst precursor in step S3 may be performed immediately after the catalyst precursor is prepared, or may be performed before use (i.e., before use in the reaction for the dehydrogenation of propane to produce propylene). Since the active component is easily oxidized and the active component in the catalyst precursor is present in the form of oxide, it is preferable that the reduction of the catalyst precursor in step S3 is performed before the dehydrogenation of propane to propylene for the convenience of transportation.

According to a preferred embodiment of the present invention, the precursor of the active component is one or more of a sulfate, a nitrate and an oxalate of the active component, preferably a nitrate of the active component. In a preferred embodiment of the present invention, the precursor of the active component is Zn (NO)₃)₂·6H₂O。

The invention also provides a method for preparing propylene by propane dehydrogenation, which comprises the step of carrying out contact reaction on propane and the catalyst to obtain propylene. Preferably, the mass space velocity of the propane is 1-10h^-1The contact temperature is 550-700 ℃, and the contact pressure is 0.05-0.15 MPa.

The catalyst for preparing propylene by propane dehydrogenation provided by the invention is matched with the microporous all-silicon molecular sieve by using non-noble metal as an active component, has low cost and good catalytic performance, and is used for propane dehydrogenation reaction to obtain propylene with high selectivity and high propylene yield.

Drawings

FIG. 1 shows the change of propane conversion, propylene yield and propylene selectivity with reaction time in the dehydrogenation of propane to propylene using the catalyst of example 2.

Detailed Description

The present invention will be described in detail with reference to examples, but the present invention is not limited to the examples.

The reagents used in the examples of the present invention are all commercially available analytical reagents;

the rotary evaporator is produced by German IKA company, and the model is RV10 digital;

the drying box is produced by Shanghai-Hengchun scientific instruments Co., Ltd, and is of a type DHG-9030A;

the muffle furnace is manufactured by CARBOLITE corporation, and is of a model CWF 1100;

the pore structure of the microporous molecular sieve obtained in the preparation example was measured by N on an adsorption apparatus of type ASAP2020-M + C from Micromeritics (USA)₂In the adsorption-desorption experiment, the specific surface area and the pore diameter of the microporous molecular sieve are calculated by adopting a BET method, and the pore volume is calculated according to a BJH model.

The content of each metal component in the prepared dehydrogenation catalyst is determined by calculating raw material feeding during preparation;

the propane conversion was calculated as follows:

propane conversion ═ amount of propane consumed by the reaction/initial amount of propane × 100%;

the propylene selectivity was calculated as follows:

propylene selectivity is the amount of propane consumed to form propylene/total propane consumption × 100%;

the propylene yield was calculated as follows:

propylene yield-actual yield of propylene/theoretical yield of propylene-100%. -propylene conversion-propylene selectivity.

Support preparation example 1

Dissolving 16.4g of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123, molecular weight of 5800, Sigma-Aldrich Chemistry) in 120mL of water, adding 320mL of hydrochloric acid with the concentration of 1.5M, stirring for 1h, then dropwise adding 32.2g of tetraethyl silicate, heating to about 40 ℃ after dropwise adding, stirring for 20h, then transferring to a stainless steel small tank, crystallizing at 120 ℃ for 24h, then filtering to collect a solid product, washing the solid product to be neutral, drying at 120 ℃, and roasting at 550 ℃ for 5h to obtain the mesoporous molecular sieve SBA-15.

Support preparation example 2

Adding 40.0g of tetraethyl Silicate and 37.5g of tetrapropylammonium hydroxide into a three-necked flask, stirring for reacting for 4 hours, transferring the material into a stainless steel small tank with a polytetrafluoroethylene lining, crystallizing for 50 hours at the temperature of 150 ℃, then filtering or centrifugally separating to obtain a white product, washing to be neutral, drying at the temperature of 120 ℃, and roasting for 10 hours at the temperature of 600 ℃ to obtain the microporous molecular sieve Silicate-1 carrier. Microporous moleculesThe average pore diameter of the sieve is

Specific surface area of 477.567m²Per g, pore volume 0.307cm³/g。

Support preparation example 3

0.25g of alumina (Al)₂O₃98 percent) and 15.01g of tetrapropylammonium hydroxide aqueous solution and 1.37g of n-butylamine are mixed and then put into a stainless steel crystallization kettle with a polytetrafluoroethylene lining for reaction for 3 hours at the temperature of 150 ℃, and after being cooled to room temperature, the mixture is mixed with 30g of silica gel (SiO)₂Content 98.4%) and 50.65g of water, the molar ratio of the mixture being SiO₂/Al₂O₃＝200，H₂O/SiO₂7. Crystallizing at 125 deg.C for 40 hr. Then filtering or centrifugally separating to obtain a white product, washing to be neutral, drying at 120 ℃, and roasting at 550 ℃ for 5 hours to obtain the mesoporous molecular sieve ZSM-5 carrier.