CN106607019A

CN106607019A - Propane dehydrogenation catalyst and preparation method thereof

Info

Publication number: CN106607019A
Application number: CN201510696926.3A
Authority: CN
Inventors: 刘杰; 荣峻峰; 马爱增; 达志坚; 刘昌呈; 谢婧新
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2015-10-23
Filing date: 2015-10-23
Publication date: 2017-05-03
Anticipated expiration: 2035-10-23
Also published as: CN106607019B

Abstract

The invention discloses a propane dehydrogenation catalyst. The propane dehydrogenation catalyst comprises 0.3 to 5.0% by mass of Pt, 0.1 to 7.0% by mass of B and 88 to 99.6% by mass of multi-walled carbon nanotubes. The preparation method comprises carrying out oxidation treatment on multi-walled carbon nanotubes as carriers through high concentration mixed acid and carrying out loading with platinum and boron to obtain the multi-walled carbon nanotube catalyst containing platinum and boron. The preparation method is simple. The propane dehydrogenation catalyst is used for a propane dehydrogenation reaction and has high reaction stability and propylene selectivity.

Description

Propane dehydrogenation catalyst and preparation method

Technical field

It is one kind with carbon nanometer specifically the present invention relates to a kind of propane dehydrogenation catalyst and preparation method Tube material is the propane dehydrogenation catalyst and preparation method of carrier.

Background technology

Pt series catalysts are one of conventional catalyst of dehydrogenating propane reaction.Dehydrogenating propane is highly endothermic, molecule The reversible reactions that number increases, high temperature and low pressure are conducive to the carrying out of dehydrogenation reaction, common reaction temperature to be 600 DEG C or so, higher reaction temperature causes Deposition During Propane Pyrolysis and the aggravation of propane deep dehydrogenation degree, selects propylene Selecting property is reduced, while can also aggravate catalyst surface carbon deposit and then cause catalyst to inactivate.By Al₂O₃Carrier The catalyst of supporting Pt is bifunctional catalyst, and surface has Pt centers and acid centre, in Pt therein The heart can be divided into single Pt centers and many Pt centers again, and many Pt centers are suitable to the structure sensitive reactions such as hydrogenolysis, carbon deposit Generation, single Pt centers are suitable to the generation of the structure insensitive reactions such as dehydrogenation and isomerization, and catalyst carrier Acid centre then easily cause skeletal isomerization, cracking and the reaction such as olefinic polymerization and then cause coking to react, And the interaction between alkene and Pt is stronger, alkene will be faster than alkane in the reaction that Pt surfaces occur. Therefore, increasing list Pt centers is conducive to dehydrogenating propane to react, and increases the dispersion of Pt and can obtain more lists Pt centers.It is general to adopt the dispersion for adding the auxiliary agents such as Sn to improve Pt metals, alkali or alkaline-earth metal etc. Introducing can neutralize the acidity of single Pt catalyst carriers, so as to improve the activity and stability of catalyst, introduce Auxiliary agent can also weaken the interaction of alkene and Pt, the dehydrogenation overall so as to improve catalyst.

Conventional dehydrogenation catalyst carrier, such as Al₂O₃It is unstable Deng high temperature opportunity tool performance and hot property, easily with Its surface metal interacts causes metallic particles to sinter.In recent years, study hotter nano-carbon material to have Good pore structure, less defect and impurity content, good antioxygenic property and preferable electronics and Heat transfer function.Used as carrier, nano-carbon material has the characteristic not available for conventional catalyst support simultaneously, Such as acidproof alkaline media, surface chemical property can be adjusted, can according to specific reaction obtain the pore size distribution that needs with And metal precursor is promoted in distribution of carbon material surface etc. by surface functional group.

Used as the carbon nanomaterial-CNT (CNTs) being widely studied, it is as catalyst carrier Before, it usually needs adopt metallic catalyst and nothing of the method for oxidation processes needed for remove its synthesis fixed The impurity such as shape carbon, while carrying out oxidation processes can also create more defective bits on the surface of CNTs, it is right CNTs carries out truncate, opening, and increases the oxygen content and oxygenated species on its surface so as to preferably grappling is golden Category etc..However, dehydrogenating propane reaction is the reaction that at high temperature (600 DEG C) are carried out, high temperature can cause oxygen-containing Species come off so as to be unfavorable for the grappling to metal, and it is unstable to easily cause catalyst performance.Wang Deng (Y WANG, N SHAH, GP HUFFMAN.Pure hydrogen production by partial dehydrogenation of cyclohexane and methylcyclohexane over nanotube-supported Pt and Pd catalysts[J].Energy and Fuels,2004,18(5):1429-1433.) prepared using infusion process To pile up Pt-SC-CNT catalyst of the taper CNT (SC-CNT) as carrier, for hexamethylene And the reaction of methyl ring methane dehydrogenation, finding the product of cyclohexane dehydrogenation only includes H₂And benzene, and hexahydrotoluene The product of dehydrogenation is only included for H₂And toluene, and Pt contents turning for 0.25wt.%Pt-SC-CNT catalyst Rate and platinum content are 1wt.%Pt/Al₂O₃Commercial catalyst it is suitable.

(Y WANG, N SHAH, FE HUGGINS, the et al.Hydrogen production by such as Wang catalytic dehydrogenation of tetralin and decalin over stacked cone carbon nanotube-supported Pt catalysts[J].Energy and Fuels,2006,20(6):2612-2615.) adopt The dehydrogenation reaction evaluation of tetrahydronaphthalene and decahydronaphthalenes is also carried out with Pt-SC-CNT catalyst, it is found that this is urged The activity of agent is better than the Pt catalyst with white carbon black and aluminium oxide as carrier, and the catalyst can be by tetrahydro Naphthalene is fully converted to naphthalene and H₂, decahydronaphthalenes can be nearly fully converted to naphthalene and H₂。

(R WANG, X SUN, B ZHANG, the et al.Hybrid Nanocarbon as a such as Wang Catalyst for Direct Dehydrogenation of Propane:Formation of an Active and Selective Core-Shell sp²/sp³Nanocomposite Structure[J].Chemistry-A European Journal, 2014,20 (21)：6324-6331.) have studied the diamond kernel (sp with different proportion²) / graphite shells (sp³) composite Nano material with carbon element dehydrogenating propane performance, find the performance of the material better than single One Nano diamond and graphite.

The content of the invention

It is an object of the invention to provide a kind of propane dehydrogenation catalyst and preparation method, the catalyst is de- in propane Good activity and stability is shown in hydrogen reaction.

The propane dehydrogenation catalyst that the present invention is provided, including Pt, 0.1～7.0 mass % of 0.3～5.0 mass % B and 88～99.6 mass % multi-walled carbon nano-tubes.

The present invention is carrier using multi-walled carbon nano-tubes, and supporting Pt and B component make catalyst, obtained Catalyst is used for propane hydrocarbon dehydrogenation reaction, with higher activity and stability.

Specific embodiment

The present invention is carrier using multi-walled carbon nano-tubes, and it is carried out after oxidation processes with high concentration mixed acid, Again Supported Pt Nanoparticles and boron, obtain carrying the multi-walled carbon nano-tubes catalyst of platinum and boron.The catalyst preparation is simple, uses There is higher reaction stability and Propylene Selectivity in dehydrogenating propane reaction.

Catalyst of the present invention includes multi-walled carbon nano-tubes, platinum and boron, preferably includes 0.5～3.5 mass % Pt, the B of 0.5～5.0 mass % and 91.5～99.0 mass % multi-walled carbon nano-tubes.

The aperture of catalyst of the present invention preferably 30.0～40.0nm, specific surface area preferably 200～250m²/ g, Total pore volume preferably 0.1～2.0cm³/g。

The multi-walled carbon nano-tubes for preparing carrier is prepared using chemical vapour deposition technique (CVD), institute Catalyst is supported cobalt catalysts, and raw material is hydrocarbon, and preparation temperature is 600～800 DEG C.

The preparation method of the catalyst that the present invention is provided, comprises the steps：

(1) dense H is used₂SO₄With dense HNO₃Impregnation mixture multi-walled carbon nano-tubes carry out oxidation processes,

(2) by the multi-walled carbon nano-tubes after (1) step oxidation processes, boron-containing compound solution impregnation is used, is done Use compound containing platinum solution impregnation after dry again, in 400～800 DEG C of roastings in noble gases after being dried, then Reduction.

The inventive method (1) step is that oxidation processes are carried out to multi-walled carbon nano-tubes, described dense H₂SO₄It is dense Spend for 95～98 mass %, dense HNO₃Concentration be 65～68 mass %, the dense H₂SO₄With dense HNO₃ Volume be 1～5：1st, preferably 2～4：1, mixed acid used is with the liquid/solid ratio of multi-wall carbon nano-tube tube material 40～60mL/g, preferably 2～12 hours, more preferably 2～10 hours time of oxidation processes.

Use dense H₂SO₄With dense HNO₃Impregnation mixture multi-wall carbon nano-tube tube material carry out the temperature of oxidation processes Spend for 20～70 DEG C, preferably 20～50 DEG C.

The inventive method (2) step is Supported Pt Nanoparticles and boron prepares catalyst, and dipping draws the platiniferous chemical combination used by platinum Thing is selected from platinum nitrate, chloroplatinic acid, potassium chloroplatinate, tetraammineplatinum chloride or acetylacetone,2,4-pentanedione platinum.Boracic used Compound is selected from ammonium pentaborate, ammonium hydrogen borate or boric acid.Impregnation liquid used and multi-walled carbon nano-tubes during dipping Liquid/solid ratio be 1～40mL/g, preferably 5～35mL/g, preferably 15～45 DEG C of dipping temperature.Impregnate the boracic Boron contents preferably 0.5～3.0mg/mL in compound solution, platinum content is preferred in compound containing platinum solution 2～8mg/mL.

(2) dipping described in step introduces boron and platinum can be using infusion process be stood, and preferred method is by oxidation Multi-walled carbon nano-tubes after reason is put in impregnation liquid, first with ultrasonic Treatment, then stands dipping.Use ultrasound wave The time of process preferably 0.3～3.0h, stands dip time preferably 4～36h, more preferably 10～30h.

(2) step dipping introduces boron and introduces after platinum, and gained solid needs drying, preferably 60～150 DEG C of baking temperature, Drying time preferably 8～15h.

It is above-mentioned to draw platinum dried solid roasting in noble gases, the preferred nitrogen of described noble gases.Institute Preferably 500～700 DEG C of the sintering temperature stated, roasting time preferably 2～6h.Described reduction preferably uses hydrogen, Preferably 500～800 DEG C, more preferably 500～700 DEG C of reduction temperature, recovery time preferably 0.5～4h.

The catalyst that the present invention is provided is applied to preparing propylene by dehydrogenating propane, and applicable dehydrogenating propane reaction temperature is 500～650 DEG C, pressure be 0.1～0.5MPa, propane can with nitrogen dilution after be passed through beds, nitrogen In propane content can be 3～10 volumes %, propane feed mass space velocity preferably 0.5～10h^-1。

The present invention is further described below by example, but the present invention is not limited to this.

Example 1

Prepare catalyst of the present invention

(1) multi-walled carbon nano-tubes carrier is prepared

(purity ＞ 95wt.%, ash ＜ 1.5wt.%, Chinese Academy of Sciences's metal grinds to take 10g multi-walled carbon nano-tubes Study carefully and provided, numbering is GT-300, prepared using chemical vapour deposition technique (CVD), used catalyst For supported cobalt catalysts, 600～800 DEG C of preparation temperature) use 500mL volume ratios to be 3：1 dense H₂SO₄/ Dense HNO₃Mixed acid carry out oxidation processes 7 hours in 25 DEG C of dippings, the dense H₂SO₄Concentration be 98 Quality %, dense HNO₃Concentration be 66 mass %, solid is washed with deionized after dipping, 120 DEG C of skies It is dried 12 hours in gas, obtains multi-walled carbon nano-tubes support C NTs.

(2) catalyst is prepared

Take multi-walled carbon nano-tubes support C NTs after 1.0g oxidation processes, be 1.6mg/mL's by B content Ammonium pentaborate solution 3.2mL and deionized water 3.8mL are placed in crucible, and in 25 DEG C ultrasonic Treatment 0.5h is used, Dipping 23.5h being stood again, solid being taken and is dried 12h in 120 DEG C, the Pt contents for placing into 5.2mL are 5.8mg/mL Platinum acid chloride solution and 1.8mL deionized waters in, use ultrasonic Treatment 0.5h, then stand dipping 23.5h, Solid is dried 12h at 120 DEG C after dipping, and 600 DEG C in N₂Middle roasting 4h, 580 DEG C in H₂Middle reduction 1h, Catalyst A is obtained, its aperture is 35.6nm, specific surface area is 115m²/ g, total pore volume are 0.943cm³/g (according to nitrogen suction-desorption curve, specific surface area is obtained using BET equations, hole is obtained using BJH equations Footpath and total pore volume), the platinum content and Boron contents in catalyst A is shown in Table 1, wherein Pt contents, Boron contents Determined by elemental microanalysis method.

Example 2

Catalyst is prepared by the method for example 1, the ammonium pentaborate solution that except for the difference that (2) step is added is 6.3mL, the platinum content and Boron contents in obtained catalyst B is shown in Table 1.

Example 3

Catalyst is prepared by the method for example 1, the ammonium pentaborate solution that except for the difference that (2) step is added is 12.6mL, the platinum content and Boron contents in obtained catalyst C is shown in Table 1.

Example 4

Catalyst is prepared by the method for example 1, the ammonium pentaborate solution that except for the difference that (2) step is added is 31.5mL, the platinum content and Boron contents in obtained catalyst D is shown in Table 1.

Comparative example 1

Multi-walled carbon nano-tubes support C NTs of the step of 1.0g examples 1 (1) preparation is taken, the B for being put into 6.3mL contains In measuring the ammonium pentaborate solution and 0.7mL deionized waters for 1.6mg/mL, ultrasonic Treatment 0.5h is used, then Dipping 23.5h is stood, solid is dried 12h at 120 DEG C after dipping, and 600 DEG C in N₂Middle roasting 4h, obtains Boron contents in catalyst M are shown in Table 1.

Comparative example 2

Multi-walled carbon nano-tubes support C NTs of the step of 1.0g examples 1 (1) preparation is taken, the Pt of 5.2mL is put into During content is for the platinum acid chloride solution and 1.8mL deionized waters of 5.8mg/mL, ultrasonic Treatment 0.5h is used, then Dipping 23.5h is stood, solid is dried 12h at 120 DEG C after dipping, and 600 DEG C in N₂Middle roasting 4h, 580 DEG C In H₂Middle reduction 1h, the platinum content in the catalyst n for obtaining is shown in Table 1.

Example 5

This example evaluates the dehydrogenating propane performance of catalyst

0.2g Catalyst packings are taken in micro-reactor, with propane that propane volume fraction is 5% and N₂It is mixed Compound is reaction raw materials, is 1.8h in 600 DEG C, 0.11MPa, propane feed mass space velocity^-1Under conditions of it is anti- 5h is answered, the meansigma methodss of interior conversion of propane and Propylene Selectivity, each catalyst reaction result during calculating reaction It is shown in Table 2.

Example 6

The catalyst B of the preparation of 0.2g examples 2 is taken, in filling in micro-reactor, with propane volume fraction as 5% Propane and N₂Mixture be reaction raw materials, be in 600 DEG C, 0.11MPa, propane feed mass space velocity 1.8h^-1Under conditions of carry out dehydrogenation reaction, react 9.5 hours and the results are shown in Table 3.

Comparative example 3

The catalyst M of the preparation of 0.2g comparative examples 1 is taken, in filling in micro-reactor, is with propane volume fraction 5% propane and N₂Mixture be reaction raw materials, 600 DEG C, 0.11MPa, propane feed mass space velocity For 1.8h^-1Under conditions of carry out dehydrogenation reaction, react 9.5 hours and the results are shown in Table 4.

Comparative example 4

The catalyst n of the preparation of 0.2g comparative examples 2 is taken, in filling in micro-reactor, is with propane volume fraction 5% propane and N₂Mixture be reaction raw materials, 600 DEG C, 0.11MPa, propane feed mass space velocity For 1.8h^-1Under conditions of carry out dehydrogenation reaction, react 9.5 hours and the results are shown in Table 5.

Table 1

Instance number	Catalyst is numbered	B content, quality %	Pt contents, quality %
				1	A	0.5	2.2
2	B	1	2.3
				3	C	2	2.4
4	D	5	2.3
				Comparative example 1	M	1	-
Comparative example 2	N	-	2.2

Table 2

Catalyst is numbered	Conversion of propane, quality %	Propylene Selectivity, quality %
			A	5.26	72.78
B	6.28	74.69
			C	4.92	70.64
D	5.47	65.61
			M	2.74	56.57
N	4.25	62.90

Table 3

Table 4

Table 5

Claims

1. Pt, the B of 0.1～7.0 mass % of a kind of propane dehydrogenation catalyst, including 0.3～5.0 mass % and The multi-walled carbon nano-tubes of 88～99.6 mass %.

2. according to the catalyst described in claim 1, it is characterised in that the catalyst includes 0.5～3.5 matter The multi-walled carbon nano-tubes of the Pt, the B of 0.5～5.0 mass % and 91.5～99.0 mass % of amount %.

3. according to the catalyst described in claim 1, it is characterised in that the aperture of the catalyst is 30.0～40.0nm, specific surface area is 200～250m²/ g, total pore volume is 0.1～2.0cm³/g。

4. a kind of preparation method of catalyst described in claim 1, comprises the steps：

5. in accordance with the method for claim 4, it is characterised in that (1) the dense H described in step₂SO₄Concentration For 95～98 mass %, dense HNO₃Concentration be 65～68 mass %, the dense H₂SO₄With dense HNO₃'s Volume is 1～5：1.

6. in accordance with the method for claim 4, it is characterised in that (1) dense H described in step₂SO₄With it is dense HNO₃The liquid/solid ratio of mixture and multi-walled carbon nano-tubes be 40～60mL/g, carry out the time of oxidation processes For 2～12 hours.

7. in accordance with the method for claim 4, it is characterised in that (1) the dense H of step₂SO₄With dense HNO₃ Impregnation mixture multi-wall carbon nano-tube tube material carry out oxidation processes temperature be 20～70 DEG C.

8. in accordance with the method for claim 4, it is characterised in that (2) noble gases described in step are nitrogen Gas.

9. in accordance with the method for claim 4, it is characterised in that (2) sintering temperature described in step is 500～700 DEG C.

10. in accordance with the method for claim 4, it is characterised in that (2) compound containing platinum described in step For platinum nitrate, chloroplatinic acid, potassium chloroplatinate, tetraammineplatinum chloride or acetylacetone,2,4-pentanedione platinum.

11. in accordance with the method for claim 4, it is characterised in that (2) boron-containing compound described in step For ammonium pentaborate, ammonium hydrogen borate or boric acid.

12. in accordance with the method for claim 4, it is characterised in that (2) described in step dipping introduce boron and The method of platinum is that the multi-walled carbon nano-tubes after oxidation processes is put in impregnation liquid, first with ultrasonic Treatment, then Stand dipping.

13. in accordance with the method for claim 4, it is characterised in that (2) step reduction uses hydrogen, also Former temperature is 500～800 DEG C.