CN110180537A - One kind is for dehydrogenating low-carbon alkane metal alloy catalyst and its preparation method and application - Google Patents

Abstract

The invention discloses one kind for dehydrating alkanes alloy catalyst and its preparation method and application.The catalyst includes one of tri- kinds of components of A, B and C, component A Pt, Pd, Rh and Ir precious metal element predecessor, accounts for 0.1~5 wt% of total catalyst weight；B component is one of Sn, Ge, Ga element predecessor, accounts for 0.1~5 wt% of total catalyst weight；Component C is carrier, accounts for 90~99.8 wt% of total catalyst weight.The present invention uses predecessor of the metallo-organic compound as B component, this predecessor is very easy to evenly dispersed in carrier surface.Hereafter active component A, finally prepd alloy catalyst are re-introduced into.The catalyst that must be prepared have partial size is small, dispersion degree is high, anti-sintering property is strong, catalytic activity is high, have good dehydrogenating low-carbon alkane performance.

Description

A metal alloy catalyst for dehydrogenation of low-carbon alkane and its preparation method and application

technical field

The invention relates to the field of industrial catalyst preparation, in particular to a metal catalyst used for the dehydrogenation of low-carbon alkanes and its preparation method and application.

Background technique

Catalytic dehydrogenation of low-carbon alkanes (C ₃ -C ₄ ) into low-carbon olefins is not only an important way to optimize the utilization of resources such as natural gas, refinery gas, oilfield associated gas, and shale gas, but also relieve the pressure of low-carbon olefins. Especially the contradiction that the supply of propylene is in short supply. Most of the low-carbon alkanes in China's natural gas, oilfield gas and refinery gas are used as fuels and have not been fully utilized, while China's low-carbon olefins, especially propylene raw materials, are seriously insufficient. If the low-carbon alkanes can be directly converted into low-carbon olefins effectively, it will not only solve the problem of insufficient sources of low-carbon olefin raw materials, but also improve the utilization value of the low-carbon alkanes. Therefore, the development of the process of producing low-carbon olefins from low-carbon alkanes is of great significance to the rational utilization of C ₃ -C ₄ alkanes and the development of new sources of low-carbon olefins.

The catalysts for the dehydrogenation of low-carbon alkanes to low-carbon olefins are mainly platinum-based catalysts and chromium-based catalysts. Although chromium-based catalysts are cheap and have low requirements for raw materials, their use is limited because Cr is a heavy metal that will pollute the environment. Platinum-based catalysts are currently the mainstream catalysts for propane dehydrogenation. Although their dehydrogenation activity is relatively good and their selectivity is high, their metal components have poor dispersion and large particle sizes, and the catalysts are prone to deactivation due to high-temperature carbon deposition. The improvement of its stability and activity is still a research hotspot.

The preparation of Pt-based catalysts is generally synthesized by traditional impregnation. In the synthesis, inorganic compounds are used as precursors of metal additive components, such as stannous chloride, so that Ga, Sn and Ge additives are introduced to help disperse the active component Pt. . However, the binding ability of inorganic compounds and the carrier is limited, resulting in uneven distribution of active components on the carrier, and the particle size of the active phase is relatively large. However, organic compounds, such as stannous octoate, have a strong binding force with the carrier, and are more uniformly distributed on the carrier, and have a strong interaction force with the metal Pt to promote the dispersion of the metal Pt.

In view of this, the present invention provides a method for preparing a metal alloy catalyst. The catalyst first introduces an organic additive component, and after the catalyst is evenly distributed on the carrier, then introduces an active component to form a highly dispersed metal alloy with uniform composition and particle size. Nano-cluster catalysts break through the shortcomings of traditional metal alloy catalysts such as uneven composition and structure, large particle size, and poor dispersion, and realize the effective regulation of synthesis-structure-performance of metal alloy catalysts.

Contents of the invention

The object of the present invention is to provide a metal alloy catalyst for the dehydrogenation of low-carbon alkane and its preparation method and application in view of the deficiencies in the prior art. The catalyst prepared by the invention is an alloy catalyst with small particle size, high dispersion, strong sintering resistance and good catalytic activity. When used in the dehydrogenation reaction of low-carbon alkanes, it has the advantages of high activity, good stability, high conversion rate of low-carbon alkanes, high selectivity of olefins, low deactivation rate and regeneration.

To achieve the above object, the present invention adopts the following technical solutions:

A metal alloy catalyst for the dehydrogenation of low-carbon alkane, the catalyst includes three components A, B and C, the A component is any one of the precursors of Pt, Pd, Rh and Ir noble metal elements, accounting for the catalyst 0.1-5 wt% of the total weight; component B is any one of the precursors of Sn, Ge and Ga elements, accounting for 0.1-5 wt% of the total weight of the catalyst; component C is the carrier, accounting for 90-5 wt% of the total weight of the catalyst 99.8 wt%.

In the A component, the Pt precursor includes one of PtCl ₄ ·5H ₂ O, H ₂ PtCl ₄ , K ₂ PtCl ₄ , (NH ₄ ) ₂ PtCl ₆ or Pt(COD)Cl ₂ ;

The precursor of Pd includes one of PdCl ₂ ·2H ₂ O, K ₂ PdCl ₄ , Pd(NH ₃ ) ₄ Cl ₂ or Pd(COD)Cl ₂ ;

Rh precursors include RhCl ₃ ·3H ₂ O, K ₃ RhCl ₆ , (NH ₄ ) ₃ RhCl ₆ , [Rh(COD)Cl] ₂ , [(COD)RhOMe)] ₂ or [(COD)RhOSi(OtBu ) ₃ ] ₂ in one;

Precursors of Ir include IrCl ₃ 3H ₂ O, K ₂ IrCl ₆ , (NH ₄ ) ₂ IrCl ₆ , [Ir(COD)Cl] ₂ , [(COD)IrOMe] ₂ or [(COD)IrOSi(OtBu) ₃ ] One of ₂ .

In the B component, the precursor of Sn includes one of dibutyltin oxide, stannous octoate, dimethyltin oxide, dioctyltin oxide, tetraphenyltin, and tetrabutyltin;

Ge precursors include one of Ge(Ph) ₄ , Ge(Me) ₄ or Ge(ETH) ₄ ;

The Ga precursor includes one of Ga(TMHD) ₃ or Ga(ACAC) ₃ .

The carrier is an oxide, including any one of SiO ₂ , Al ₂ O ₃ , MgO, TiO ₂ or MgAl ₂ O ₄ .

A method for preparing metal catalysts for the dehydrogenation of low-carbon alkane, specifically comprising the following steps:

(1) Weigh the oxide as a carrier, impregnate component B, then dry and roast;

(2) impregnating component A on the carrier containing component B in step (1), then drying and roasting to obtain the low-carbon alkane dehydrogenation metal alloy catalyst.

The soaking time is 1 h to 24 h; the drying is at 60°C to 150°C for 1 h to 12 h, and the roasting is at 400°C to 650°C for 2 h to 8 h. The catalyst is used for the dehydrogenation reaction of low-carbon alkanes, the low-carbon alkanes include alkanes with 2-4 carbon atoms, the reaction temperature is 400°C-600°C, and the mass space velocity is 0.5-20 h ^-1 .

The low-carbon alkane is propane or isobutane, and the dehydrogenation reaction is carried out in a fixed-bed reactor.

During the whole reaction process, the dehydrogenation of alkanes mainly produces the corresponding alkenes, and the by-products of cracking, isomerization and polymerization are very small. Therefore, the selectivity of dehydrogenation of alkanes to the corresponding alkenes is very high, up to 99% under suitable conditions, and even nearly 100% to the corresponding alkenes.

The beneficial effect of the present invention is that: the catalyst prepared by the present invention firstly introduces the organometallic additive component to replace the traditional inorganic additive component, and after the catalyst is evenly distributed on the carrier, then introduces the active component to form a composition, particle Highly dispersed metal nanocluster catalysts with uniform diameters break through the shortcomings of the traditional impregnation method to prepare metal alloy catalysts, such as uneven composition and structure, large particle size, and poor dispersion, and realize effective regulation of the synthesis-structure-performance of metal alloy catalysts; A catalyst with high comprehensive performance. It has high selectivity for dehydrogenation of alkanes to corresponding olefins, high single-pass conversion rate, slow catalyst deactivation, and good regeneration performance.

Description of drawings

Figure 1 is the STEM image of the synthesized Rh-Sn/Al ₂ O ₃ catalyst.

Detailed ways

In order to better understand the technical solutions of the present invention, further detailed descriptions will be given below in conjunction with specific embodiments and accompanying drawings, but the protection scope of the present invention will not be limited.

Example 1

Weigh 5.00 g of a compound (stannous octoate) loaded with 0.037 g of Sn on aluminum oxide (Al ₂ O ₃ ). After immersing in stannous octoate solution at room temperature for 6 h, dry at 120 °C for 8 h, and bake at 500 °C for 4 h. The carrier loaded with active component Sn was loaded with 0.061 g of Pt compound (PtCl ₄ 5H ₂ O), impregnated at room temperature for 6 h, dried at 120 °C for 12 h, and calcined at 550 °C for 4 h to obtain Pt-Sn/Al ₂ O ₃ catalysts. In a fixed-bed tubular reactor filled with 1 g of the catalyst prepared in Example 1, the reactant is propane, the reaction temperature is 550 °C, the reaction pressure is normal pressure, the propane weight hourly space velocity is 8 h ^-1 , and the ratio of hydrogen to hydrocarbon is Under the condition of 1, the conversion rate of propane is 38%, and the selectivity of propylene is 99.3%.

Example 2

A compound (Ge(Ph) ₄ ) of 0.042 g Ge supported on 5.00 g of silicon dioxide (SiO ₂ ) was weighed. After immersing in Ge(Ph) ₄ solution at room temperature for 6 h, it was dried at 120 °C for 8 h and calcined at 500 °C for 4 h. Pt-Ge/SiO ₂ catalysts were obtained by loading 0.061 g of Pt compound (H ₂ PtCl ₄ ) on the support of the active component Ge, impregnated at room temperature for 6 h, dried at 120 °C for 12 h, and calcined at 520 °C for 4 h. In a fixed-bed tubular reactor filled with 1 g of the catalyst prepared in Example 2, the reactant is propane, the reaction temperature is 550 °C, the reaction pressure is normal pressure, the propane weight hourly space velocity is 5 h ^-1 , and the ratio of hydrogen to hydrocarbon is Under the condition of 1, the conversion rate of propane is 37.5%, and the selectivity of propylene is 98%.

Example 3

A compound (Ga(TMHD) ₃ ) loaded with 0.022 g Ga on 3.00 g magnesium oxide (MgO) was weighed. After immersing in Ga(TMHD) ₃ solution at room temperature for 6 h, it was dried at 120 °C for 8 h and calcined at 500 °C for 4 h. 0.061 g of Pt compound (K ₂ PtCl ₄ ) was loaded on the carrier loaded with active component Ga, impregnated at room temperature for 6 h, dried at 120 °C for 12 h, and calcined at 540 °C for 4 h to prepare the Pt-Ga/MgO catalyst. In a fixed-bed tubular reactor filled with 1 g of the catalyst prepared in Example 3, the reactant is propane, the reaction temperature is 550 °C, the reaction pressure is normal pressure, the propane weight hourly space velocity is 6 h ^-1 , and the ratio of hydrogen to hydrocarbon is Under the condition of 1, the conversion rate of propane is 37%, and the selectivity of propylene is 99%.

Example 4

6.00 g of titanium dioxide (TiO ₂ ) loaded with 0.037 g of Sn compound (dibutyltin oxide) was weighed. After immersing in HSnBu ₃ solution at room temperature for 6 h, it was dried at 120 °C for 8 h and calcined at 500 °C for 4 h. Pd-Sn/TiO ₂ was obtained by loading 0.048g of Pd compound (PdCl ₂ 2H ₂ O) on the carrier loaded with active component Sn, impregnated at room temperature for 6 h, dried at 120 °C for 12 h, and calcined at 550 °C for 4 h. catalyst. In a fixed-bed tubular reactor filled with 1 g of the catalyst prepared in Example 4, the reactant is propane, the reaction temperature is 550 °C, the reaction pressure is normal pressure, the propane weight hourly space velocity is 5 h ^-1 , and the ratio of hydrogen to hydrocarbon is Under the condition of 1, the conversion rate of propane is 35%, and the selectivity of propylene is 97.5%.

Example 5

A compound (Ge(Me) ₄ ) loaded with 0.042 g Ge on 5.00 g magnesium aluminum crystallite (MgAl ₂ O ₄ ) was weighed. After immersing in Ge(Me) ₄ solution at room temperature for 6 h, it was dried at 120 °C for 8 h, and then calcined at 500 °C for 4 h. Pd-Ge/MgAl ₂ O ₄ catalyst was obtained by loading 0.048 g of Pd compound (K ₂ PdCl ₄ ) on the support of the active component Ge, impregnated at room temperature for 6 h, dried at 120 °C for 12 h, and calcined at 550 °C for 4 h. . In a fixed-bed tubular reactor filled with 1 g of the catalyst prepared in Example 6, the reactant is propane, the reaction temperature is 550 °C, the reaction pressure is normal pressure, the propane weight hourly space velocity is 3 h ^-1 , and the ratio of hydrogen to hydrocarbon is Under the condition of 1, the conversion rate of propane is 36.5%, and the selectivity of propylene is 93%.

Example 6

A compound (Ga(ACAC) ₃ ) in which 5.00 g of aluminum oxide (Al ₂ O ₃ ) was loaded with 0.022 g of Ga was weighed. After immersing in Ga(ACAC) ₃ solution at room temperature for 6 h, it was dried at 120 °C for 8 h and calcined at 500 °C for 4 h. _{Pd - Ga} / _{Al2O3 catalyst} . In a fixed-bed tubular reactor filled with 1 g of the catalyst prepared in Example 5, the reactant is propane, the reaction temperature is 550 °C, the reaction pressure is normal pressure, the propane weight hourly space velocity is 4 h ^-1 , and the ratio of hydrogen to hydrocarbon is Under the condition of 1, the conversion rate of propane is 37%, and the selectivity of propylene is 96.5%.

Example 7

5.00 g of silicon dioxide (SiO ₂ ) loaded with 0.037 g of Sn (dimethyl tin oxide) was weighed. After immersing in Sn(HAC) ₂ solution at room temperature for 6 h, it was dried at 120 °C for 8 h, and then baked at 500 °C for 4 h. The carrier loaded with active component Sn was loaded with 0.058g Rh compound (RhCl ₃ 3H ₂ O), impregnated at room temperature for 6 h, dried at 120 °C for 12 h, and calcined at 520 °C for 4 h to obtain Rh-Sn/SiO ₂ catalyst. In a fixed-bed tubular reactor filled with 1 g of the catalyst prepared in Example 7, the reactant is propane, the reaction temperature is 550 °C, the reaction pressure is normal pressure, the weight hourly space velocity of propane is 3 h ^-1 , and the ratio of hydrogen to hydrocarbon is Under the condition of 1, the conversion rate of propane is 39%, and the selectivity of propylene is 95.8%.

Example 8

A compound (Ge(ETH) ₄ ) loaded with 0.042 g Ge on 3.00 g magnesium oxide (MgO) was weighed. After immersing in Ge(ETH) ₄ solution at room temperature for 6 h, it was dried at 120 °C for 8 h and calcined at 500 °C for 4 h. 0.058 g of Rh compound (K ₃ RhCl ₆ ) was loaded on the support with active component Ge, impregnated at room temperature for 6 h, dried at 120 ℃ for 12 h, and calcined at 540 ℃ for 4 h to prepare the Rh-Ge/MgO catalyst. In a fixed-bed tubular reactor filled with 1 g of the catalyst prepared in Example 8, the reactant is propane, the reaction temperature is 550 °C, the reaction pressure is normal pressure, the propane weight hourly space velocity is 6 h ^-1 , and the ratio of hydrogen to hydrocarbon is Under the condition of 1, the conversion rate of propane is 33%, and the selectivity of propylene is 96.5%.

Example 9

A compound (Ga(TMHD) ₃ ) loaded with 0.022 g of Ga on 10.00 g of titanium dioxide (TiO ₂ ) was weighed. After immersing in Ga(TMHD) ₃ solution at room temperature for 6 h, it was dried at 120 °C for 8 h and calcined at 500 °C for 4 h. 0.058g of Rh compound (NH ₄ ) ₃ RhCl ₆ was loaded on the support with active component Ga, impregnated at room temperature for 6 h, dried at 120 °C for 12 h, and calcined at 550 °C for 4 h to prepare the Rh-Ga/TiO ₂ catalyst . In a fixed-bed tubular reactor filled with 1 g of the catalyst prepared in Example 9, the reactant is propane, the reaction temperature is 550 °C, the reaction pressure is normal pressure, the propane weight hourly space velocity is 4 h ^-1 , and the ratio of hydrogen to hydrocarbon is Under the condition of 1, the conversion rate of propane is 31.5%, and the selectivity of propylene is 96.5%.

Example 10

A compound (dioctyltin oxide) loaded with 0.037 g of Sn on 5.00 g of magnesium aluminum crystallite (MgAl ₂ O ₄ ) was weighed. After immersing in HSnPh ₃ solution at room temperature for 6 h, it was dried at 120 °C for 8 h, and then baked at 500 °C for 4 h. 0.048 g of Ir compound (IrCl ₃ 3H ₂ O) was loaded on the carrier loaded with active component Sn, impregnated at room temperature for 6 h, dried at 120 °C for 12 h, and calcined at 550 °C for 4 h to obtain Ir-Sn/MgAl _{2 O4} catalyst. In a fixed-bed tubular reactor filled with 1 g of the catalyst prepared in Example 10, the reactant is propane, the reaction temperature is 550 °C, the reaction pressure is normal pressure, the propane weight hourly space velocity is 4 h ^-1 , and the ratio of hydrogen to hydrocarbon is Under the condition of 1, the conversion rate of propane is 39%, and the selectivity of propylene is 97.8%.

Example 11

A compound (Ge(Ph) ₄ ) in which 5.00 g of aluminum oxide (Al ₂ O ₃ ) was loaded with 0.042 g of Ge was weighed. After immersing in Ge(Ph) ₄ solution at room temperature for 6 h, it was dried at 120 °C for 8 h and calcined at 500 °C for 4 h. Ir-Ge/Al ₂ O ₃ was obtained by loading 0.048 g of Ir compound (K ₂ IrCl ₆ ) on the support with active component Ge, impregnated at room temperature for 6 h, dried at 120 °C for 12 h, and calcined at 500 °C for 4 h. catalyst. In a fixed-bed tubular reactor filled with 1 g of the catalyst prepared in Example 11, the reactant is propane, the reaction temperature is 550 °C, the reaction pressure is normal pressure, the propane weight hourly space velocity is 4 h ^-1 , and the ratio of hydrogen to hydrocarbon is Under the condition of 1, the conversion rate of propane is 33.5%, and the selectivity of propylene is 96.5%.

Example 12

5.00 g of silicon dioxide (SiO ₂ ) loaded with 0.022 g of Ga compound (Ga(TMHD) ₃ ) was weighed. After immersing in Ga(TMHD) ₃ solution at room temperature for 6 h, it was dried at 120 °C for 8 h and calcined at 500 °C for 4 h. Ir-Ga/SiO ₂ catalyst was prepared by loading 0.048g of Ir compound (NH ₄ ) ₂ IrCl ₆ on the support with active component Ga, impregnated at room temperature for 6 h, dried at 120 °C for 12 h, and calcined at 520 °C for 4 h. . In a fixed-bed tubular reactor filled with 1 g of the catalyst prepared in Example 12, the reactant is propane, the reaction temperature is 550 °C, the reaction pressure is normal pressure, the propane weight hourly space velocity is 4 h ^-1 , and the ratio of hydrogen to hydrocarbon is Under the condition of 1, the conversion rate of propane is 31.5%, and the selectivity of propylene is 96.5%.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (8)

1. one kind is used for dehydrogenating low-carbon alkane metal alloy catalyst, it is characterised in that: the catalyst includes tri- kinds of A, B and C Component, any one in component A Pt, Pd, Rh and Ir precious metal element predecessor, account for total catalyst weight 0.1~ 5wt%；B component is any one in Sn, Ge and Ga element predecessor, accounts for 0.1~5 wt% of total catalyst weight；Component C For carrier, 90~99.8 wt% of total catalyst weight are accounted for.

2. according to claim 1 be used for dehydrogenating low-carbon alkane metal alloy catalyst, it is characterised in that: the A group In point, the predecessor of Pt includes PtCl₄·5H₂O、H₂PtCl₄、K₂PtCl₄、(NH₄)₂PtCl₆Or Pt (COD) Cl₂Middle one kind；

The predecessor of Pd includes PdCl₂·2H₂O、K₂PdCl₄、Pd(NH₃)₄Cl₂Or Pd (COD) Cl₂One of；

The predecessor of Rh includes RhCl₃·3H₂O、K₃RhCl₆、(NH₄)₃RhCl₆、 [Rh(COD)Cl]₂、[(COD)RhOMe)]₂Or [(COD)RhOSi(OtBu)₃]₂One of；

The predecessor of Ir includes IrCl₃·3H₂O、K₂IrCl₆、(NH₄)₂IrCl₆、[Ir(COD)Cl]₂、[(COD)IrOMe]₂Or [(COD)IrOSi(OtBu)₃]₂One of.

3. according to claim 1 be used for dehydrogenating low-carbon alkane metal alloy catalyst, it is characterised in that: the B group Point in, the predecessor of Sn include Dibutyltin oxide, stannous octoate, dimethyl tin oxide, di-n-octyltin oxide, tetraphenyltin, One of tetrabutyltin；

The predecessor of Ge includes Ge (Ph)₄、Ge(Me)₄Or Ge (ETH)₄One of；

The predecessor of Ga includes Ga (TMHD)₃Or Ga (ACAC)₃One of.

4. according to claim 1 be used for dehydrogenating low-carbon alkane metal alloy catalyst, it is characterised in that: the carrier is Oxide, including SiO₂、Al₂O₃、MgO、TiO₂Or MgAl₂O₄In any one.

5. a kind of method for dehydrogenating low-carbon alkane metallic catalyst prepared as described in claim 1 ~ 4 is any, feature It is: specifically includes the following steps:

(1) oxide is weighed, as carrier, impregnates B component, then through drying, roasting；

(2) component A is impregnated in step (1) above the carrier containing B component, then the lower alkanes are made in drying, roasting Hydrocarbon dehydrogenation metal alloy catalyst.

6. the preparation method according to claim 5 for dehydrogenating low-carbon alkane metal alloy catalyst, it is characterised in that: The dip time is the h of 1 h~24；The drying be in 60 DEG C~150 DEG C drying h of 1 h~12, roasting be The h of 2 h~8 is roasted at 400 DEG C~650 DEG C.

7. a kind of application of catalyst as described in claim 1, it is characterised in that: the catalyst is for the de- of low-carbon alkanes Hydrogen reaction, the low-carbon alkanes include the alkane of 2-4 carbon atom, and 400 DEG C~600 DEG C of reaction temperature, mass space velocity 0.5 ~20 h^-1。

8. application according to claim 7, it is characterised in that: the low-carbon alkanes are propane or iso-butane, dehydrogenation reaction It is carried out in fixed bed reactors.