CN103464149B

CN103464149B - Ru/MWCNTs Catalysts and its preparation method

Info

Publication number: CN103464149B
Application number: CN201310457367.1A
Authority: CN
Inventors: 李利民; 徐三魁; 张朋; 李蕊; 郭楠楠; 焦健侠
Original assignee: Zhengzhou University
Current assignee: Zhengzhou University
Priority date: 2013-09-30
Filing date: 2013-09-30
Publication date: 2016-05-04
Anticipated expiration: 2033-09-30
Also published as: CN103464149A

Abstract

The invention belongs to catalyst technical field, particularly a kind of Ru/MWCNTs Catalysts and its preparation method. Described catalyst is as carrier, with supercritical CO taking multi-walled carbon nano-tubes₂For steeping medium makes. The catalyst that the present invention obtains has shown the activity of higher catalyst and good stability in glucose hydrogenation reaction.

Description

Ru/MWCNTs Catalysts and its preparation method

Technical field

The invention belongs to catalyst technical field, particularly a kind of Ru/MWCNTs Catalysts and its preparation method.

Background technology

Supported ruthenium C catalyst is widely used in synthetic, the hydrogenation of Glucose sorbierite of ammonia, containing benzene ring compoundHydrogenation etc. It is the main path of preparing at present sorbierite that By Catalytic Hydrogenation of Glucose is prepared sorbierite, and sorbierite is widely used in foodThe fields such as product, medicine, cosmetics. Under certain pressure, using batch reactor or circulating thermopnore as reactor, with denseDegree be 50% glucose solution as raw material, under catalyst action, adopt the method for liquid phase catalytic hydrogenation to make sorbierite.

At present, adopting catalytic hydrogenation legal system is using nickel as active component for sorbierite catalyst major part used. WithBefore mainly select Raney's nickel as catalyst, this catalyst cost is lower. Afterwards, due to nickel catalyst carried activityHeight, nickel catalyst carried having obtained applied widely. But in use easily there is the loss of nickel in Raney nickel, asIn glucose hydrogenation process, can there is the dissolving of nickel, thereby cause catalyst activity to reduce, and the containing of nickel in sorbitol solutionMeasure higher. In food, medicine and cosmetic industry, nickel can residual maximum be 2mg/kg, therefore the nickel in sorbierite mustMust be removed, the nickel of removing in sorbierite can increase production cost greatly. In recent years, people to noble metal as grapeSugar Hydrogenation is studied for the catalyst of sorbierite, and result shows, the activity of load ruthenium catalyst is best, catalytic activityBe all better than Raney nickel the service life of catalyst. Load capacity is 1% ruthenium catalyst catalysis glucose hydrogenation generation sorbThe conversion ratio of alcohol is suitable with Raney nickel selective and that load capacity is 66.78%. Because the price of ruthenium is high compared with nickel, therefore needUse the carrier of Large ratio surface, so that the use amount of ruthenium is fully used, is reduced to metal Ru. At present, using active carbon as carryingThere are reports for the ruthenium C catalyst (Ru/AC) of body.

CNT (CNTs) is a kind of new carbon, is divided into SWCN (SWCNTs), double-walled carbon nano-tubeAnd multi-walled carbon nano-tubes (MWCNTs) (DWCNTs). CNT has unique conduction and heat conductivility, also adds and hasThe stability that higher specific surface, regulatable hollow nano luminal structure are become reconciled, therefore as the carrier of loaded catalystThere is good application prospect in catalytic hydrogenation, dehydrogenation and electro-catalysis field.

CNT is different from the aperture structure of active carbon and the kind of Active sites, general absorbent charcoal carrierActivated centre is all kinds of oxygen-containing functional groups and the surface texture defect on surface, and the size distribution scope of active carbonWide, the thinner micropore of part is difficult to be utilized in reaction; CNT is different, and the aperture of nanotube is in the majority with mesopore,And because CNT is to be developed by graphite, it mainly forms several layers to tens of layers by the carbon atom that is hexagonal arrayCoaxial pipe composition, thereby contain a large amount of not paired delocalized electron (sp²Pi-electron) move about along tube wall, these conjugation delocalizations π electricitySon forms the main absorption depocenter of metal, and such adsorption site is conducive to the catalytic action of catalyst; Carbon nanometer simultaneouslyThe pore-size distribution of pipe is more even, and specific surface energy is well utilized.

But how by active metal load or insert CNT surfaces externally and internally, and the effective particle of control load metalDegree is the important step of effectively applying CNT. Main method has original position arc discharge method, volatile compounds at presentVapour deposition process and wet chemical method. Original position arc discharge method and vapour deposition process are being prepared metal nanometer line and metal film sideFace has been obtained good effect, but is difficult to effectively control the particle size of metal, and the cost of while method is also more expensive; WetChemical method is owing to being applicable to most metals, is therefore the simplest and applies maximum methods at catalytic field. Filling out of metalEnter and load effect depends primarily on the contact angle between surface tension and liquid and the CNT wall of liquid medium. For tailThe CNT of end opening, when the surface tension of steeping liq medium is less than 100mN/m, carbon nano tube surface can be by liquid instituteWetting. Use this wet chemical method successfully discontinuous metal nanoparticle to be introduced to the CNT of tens nanometers at presentThe inwall in hole. But, in the time that nanometer pore internal diameter only has several nanometer, but run into great difficulty (referring to PanXL, BAOXH.TheEffectsofConfinementinsideCarbonNanotubesonCatalysis[J],Accountsofchemicalresearch, 2011,44 (8): 553-562). The people such as Ugarte observe discovery:（Ugarte,D.Chatelain,A.;deHeer,W.A.NanocapillarityandchemistryincarbonNanotubes[J] .Science, 1996,274:1897-1899) because capillarity and wetting behavior are subject to aperture sizeRestriction, in the time that the diameter of CNT is less than 3nm, nanotube almost can not be filled. But the tiny nanotube in aperture forCatalysis is again even more important, because the less nanotube in aperture has larger specific surface, and in tiny aperture nanometerGuan Li, can obtain the metallic of nanometer or Subnano-class, and such nano-metal particle generally has better catalyticEnergy. Some researchers process by ultrasonic wave and mechanical agitation further promotes the effusion of air in duct and entering of reactantEnter, also utilize ethanol, benzene, acetone and other organic solvent to replace aqueous medium, reduce the surface tension of metal precursor solution, improveActive component enters the effect of nanotube. These ways have certain effect, but still have certain difficulty for thinner CNT.Li Rui etc. (application [D] of supercritical fluid deposition method in the preparation of ruthenium C catalyst. Zhengzhou: Zhengzhou University, 2011:45-50)Once do carrier with CNT and carry out the dipping of active component with supercritical process, but fail to obtain significant result.

Summary of the invention

The object of this invention is to provide a kind of Ru/MWCNTs Catalysts and its preparation method, described catalyst is livedProperty is high, good stability.

For solving the problems of the technologies described above, the technical solution used in the present invention is as follows:

Ru/MWCNTs catalyst, described catalyst is as carrier, with supercritical CO taking multi-walled carbon nano-tubes₂For dipping is situated betweenMatter is carried on Ru on carrier and makes.

The internal diameter of described multi-walled carbon nano-tubes is 2-5nm, external diameter < 8nm, and length is 0.5-2 μ m.

With supercritical CO₂While processing for steeping medium, treatment temperature is 50-80 DEG C, and pressure is 8.0-10.0MPa, dippingAdsorption time is 0.5-2 hour.

Comparatively concrete, step is as follows:

1) in reactor, add successively CNT and RuCl₃Methanol solution, after off-response still, be warming up to 50-80DEG C, be then filled with CO₂To the pressure of 8.0-10.0MPa, dipping absorption 0.5～2 hour;

2) be cooled to room temperature, CNT is taken out and is dried obtain catalyst precursors;

3) by catalyst precursors in 190-210 DEG C of reduction 1-3h, then in 320-400 DEG C of reduction 0.5-2h, cooling afterObtain described Ru/MWCNTs catalyst.

Wherein, when being put into reactor, CNT is placed in hanging basket, and that hanging basket occupy reactor bottom is above three/One place. By CNT be placed in hanging basket relatively CNT to be placed on reactor bottom dipping effect better.

Described hanging basket is Round Porous cylindricality, the about 10ml of volume, and for avoiding carrier to spill, stainless steel can be spread in hanging basket bottomNet.

The mass ratio of CNT and Ru is 0.6:0.025-0.035. RuCl₃Methanol solution in the concentration of Ru preferredFor 0.032g/ml, certainly, under the prerequisite of mass ratio that ensures CNT and Ru, be not limited to this concentration.

Step 2) in baking temperature be 70-90 DEG C preferably 80 DEG C.

Step 2) in, be cooled to after room temperature, in reactor, pass in water when air release after emptying again. CO after reaction₂LogicalCross emptying after water, the methyl alcohol adding is with CO₂Overflow and absorbed by water. After testing, residual without methyl alcohol in catalyst.

In step 3) by catalyst precursors in 200 DEG C of reductase 12 h, then in 350 DEG C reduction 1h.

More specifically, reactions steps is as follows:

1) accurately take CNT and put into the hanging basket of autoclave; By a certain amount of RuCl₃·xH₂O(Ru content37%), dissolving with methyl alcohol, is 0.032g containing Ru in 1ml solution, gets above-mentioned solution and adds in reactor, the matter of CNT and RuAmount is than being 0.6:0.032. Close after kettle cover leak test, temperature in the kettle is raised to 50 DEG C-80 DEG C, then is filled with CO₂To 8.0MPa-The pressure of 10.0MPa, dipping absorption 0.5-2 hour;

2) naturally cool to room temperature, in reactor, pass into when air release in water after emptying. CNT is equipped with in taking-upHanging basket, puts into 80 DEG C of baking ovens dry, obtains catalyst precursors;

3) gained catalyst precursors is put into the quartz ampoule of tubular heater, with hydrogen reducing, 200 DEG C of reduction2h, 350 DEG C of reduction 1h, then turn off temperature controller, when stove cool to room temperature to be heated, sample and obtain Ru/MWCNTs catalyst sampleProduct.

Supercritical fluid (SCF) technology is the new technology that developed recently gets up, and supercritical fluid refers to and is in critical-temperature(Tc) the special fluid and on critical pressure (Pc), supercritical fluid has a series of properties: its viscosity is lower, expandsLoose coefficient is large, and these character approach gas, thus supercritical fluid is had good flow, the performance such as mass transfer; Shooting flowBody has very low surface tension, makes it have excellent surface wettability and penetrating power. Due to the height of supercritical fluidDiffusivity, strong dissolubility, excellent surface wettability etc. can enter nanometer the active component transmission being dissolved in whereinThe inside of pipe, effectively utilizes the inner surface of nanotube. In common supercritical fluid, research is overcritical two comparatively widelyCarbonoxide (SCCO₂), because supercritical carbon dioxide have do not fire, nontoxic, inexpensive, environmental protection and approach the critical-temperature of room temperatureLower critical pressure (Tc=31.1 DEG C, Pc=7.38MPa), shows wide application prospect.

The present invention solves the variety of issue existing in prior art, application supercritical CO₂For steeping medium, face by superThe selection of boundary's treatment conditions, and prepare Ru/MWCNTs as the suitable aperture of CNT of carrier and the selection of length and urgeAgent, the appropriate depth that makes presoma ruthenium trichloride enter CNT, the granularity of ruthenium is less, aobvious in glucose hydrogenation reactionShow apparently higher than the activity of Ru/AC catalyst and good stability.

In the method that the present invention provides, the activity that the CNT of described length and pipe diameter size obtains is best, wherein,Nanotube internal diameter has impact to the particles of active components size generating, and then affects reactivity. For supercritical impregnation, processTime, pressure, temperature have impact for the activity of the catalyst obtaining. As short in the processing time, the load of active component stillDeficiency, the processing time is long there will be active downward trend. Reason is the strong diffusivity of supercritical medium, makes dippingComponent is easier to enter in pipe, and long dip time can make more active component enter CNT depths, this partActive metal acting on to a certain degree by weakened in glucose hydrogenation reaction. Equally, supercritical temperature and pressure also canResult is exerted an influence. Because glucose hydrogenation reaction is what to carry out in 50% the aqueous solution, and reactant grapeGlycan molecule and product sorbierite molecular dimension are bigger than normal again comparatively speaking, and glucose molecule enters the difficulty or ease with sorbierite molecule escapingActivity is had to certain influence. For the multi-walled carbon nano-tubes of certain specification, while selecting suitable supercritical temperature, pressure, processingBetween condition, can prepare the catalyst of high activity, high stability.

Catalyst of the present invention is not only applicable to the reaction of hydrogenation of Glucose sorbierite, be also applicable to ammonia synthetic, containing benzeneThe hydrogenation reaction of cycle compound.

Compared with prior art, tool has the following advantages in the present invention:

The catalyst that the present invention obtains in glucose hydrogenation reaction, shown apparently higher than the activity of Ru/AC catalyst andGood stability.

Brief description of the drawings

Fig. 1 is the transmission electron microscope picture of catalyst of the present invention;

Fig. 2 is the transmission electron microscope picture of the catalyst of water impregnation process;

Fig. 3 is that catalyst sample of the present invention is through ultrasonic wave transmission electron microscope picture after treatment;

Fig. 4 is that the catalyst of water impregnation process is through ultrasonic wave transmission electron microscope picture after treatment.

Detailed description of the invention

With specific embodiment, technical scheme of the present invention is described below, but protection scope of the present invention is not limited to this:

Embodiment 1

Ru/MWCNTs catalyst, preparation method is as follows:

By the CNT of 0.6g (internal diameter 2～5nm, length: 0.5～2 μ m) puts into 50ml with polytetrafluoroethylene (PTFE)In the hanging basket of the reactor of lining, add 1mLRuC1₃/CH₃OH solution (containing Ru0.032g in every ml soln, lower same). Will be anti-Answer still sealing, by reactor be raised to 60 DEG C with high pressure syringe pump by CO₂Be filled with, until pressure reaches 10.0MPa, remain overcriticalAfter condition 2 hours, cooling, pressure release, by emptying after passing into when air release in water in reactor, then unloads still and obtains Ru/MWCNTs catalyst precursors (lower same). Predecessor is dried to 4 hours in 80 DEG C of insulating boxs, and dried sample is put into tubular typeIn the quartz ampoule of heating furnace, with hydrogen reducing, at 200 DEG C of reductase 12 h, 350h DEG C of reduction 1h, stops heating, continues logical but hydrogen-cooledDuring to room temperature, obtain Ru/MWCNTs catalyst sample.

Determination of activity result: unit quantity ruthenium, unit interval hydrogen-consuming volume 75.58mmolmin^-1g^-1Ru。

Embodiment 2

Ru/MWCNTs catalyst, preparation method is as follows:

By the CNT of 0.6g (internal diameter 2～5nm, length: 0.5～2 μ m) puts into 50ml with polytetrafluoro linerIn the hanging basket of reactor, add 0.8mLRuC1₃/CH₃OH solution. By reactor sealing, reactor is raised to 80 DEG C and uses high pressure injectionPenetrate pump by CO₂Be filled with, until pressure reaches 9.0MPa, maintain super critical condition after 0.5 hour, cooling, pressure release, unloads still and obtains Ru/MWCNTs catalyst precursors. Then in 80 DEG C of insulating boxs, be dried 4 hours, dried sample is put into the stone of tubular heaterIn English pipe, with hydrogen reducing, at 200 DEG C of reductase 12 h, 350h DEG C of reduction 1h, stops heating, while continuing logical hydrogen cool to room temperature,Obtain Ru/MWCNTs catalyst sample.

Determination of activity result: unit quantity ruthenium, unit interval hydrogen-consuming volume are 73.32mmolmin^-1g^-1Ru。

Embodiment 3

Ru/MWCNTs catalyst, preparation method is as follows:

By the CNT of 0.6g (internal diameter 2～5nm, length: 0.5～2 μ m) puts into 50ml with polytetrafluoro linerIn the hanging basket of reactor, add 1.1mLRuC1₃/CH₃OH solution. By reactor sealing, reactor is raised to 50 DEG C and uses high pressure injectionPenetrate pump by CO₂Be filled with, until pressure reaches 10.0MPa, maintain super critical condition after 2 hours, cooling, pressure release, unloads still and obtains Ru/MWCNTs catalyst precursors. Then in 80 DEG C of insulating boxs, be dried 4 hours, dried sample is put into the stone of tubular heaterIn English pipe, with hydrogen reducing, at 200 DEG C of reductase 12 h, 350h DEG C of reduction 1h, stops heating, while continuing logical hydrogen cool to room temperature,Obtain Ru/MWCNTs catalyst sample.

Determination of activity result: unit quantity ruthenium, unit interval hydrogen-consuming volume 78.66mmolmin^-1g^-1Ru。

Embodiment 4

Ru/MWCNTs catalyst, preparation method is as follows:

By the CNT of 0.6g (internal diameter 2～5nm, length: 0.5～2 μ m) puts into 50ml with polytetrafluoro linerIn the hanging basket of reactor, add 1mLRuC1₃/CH₃OH solution. By reactor sealing, reactor is raised to 80 DEG C with high-pressure injectionPump is by CO₂Be filled with, until pressure reaches 8.0MPa, maintain super critical condition after 1 hour, cooling, pressure release, unloads still and obtains Ru/MWCNTs catalyst precursors. Then in 80 DEG C of insulating boxs, be dried 4 hours, dried sample is put into the stone of tubular heaterIn English pipe, with hydrogen reducing, at 200 DEG C of reductase 12 h, 350h DEG C of reduction 1h, stops heating, while continuing logical hydrogen cool to room temperature,Obtain Ru/MWCNTs catalyst sample.

Determination of activity result: unit quantity ruthenium, unit interval hydrogen-consuming volume 85.84mmolmin^-1g^-1Ru。

Embodiment 5

Ru/MWCNTs catalyst, preparation method is as follows:

By the CNT of 0.6g (internal diameter 2～5nm, length: 0.5～2 μ m) puts into 50ml with polytetrafluoro linerIn the hanging basket of reactor, add 0.9mLRuC1₃/CH₃OH solution. By reactor sealing, reactor is raised to 50 DEG C and uses high pressure injectionPenetrate pump by CO₂Be filled with, until pressure reaches 10.0MPa, maintain super critical condition after 1 hour, cooling, pressure release, unloads still and obtains Ru/MWCNTs catalyst precursors. Then in 90 DEG C of insulating boxs, be dried 4 hours, dried sample is put into the stone of tubular heaterIn English pipe, with hydrogen reducing, at 200 DEG C of reductase 12 h, 350h DEG C of reduction 1h, stops heating, while continuing logical hydrogen cool to room temperature,Obtain Ru/MWCNTs catalyst sample.

Determination of activity result: unit quantity ruthenium, unit interval hydrogen-consuming volume 77.90mmolmin^-1g^-1Ru。

Embodiment 6

Ru/MWCNTs catalyst, preparation method is as follows:

By the CNT of 0.6g (internal diameter 2～5nm, length: 0.5～2 μ m) puts into 50ml with polytetrafluoro linerIn the hanging basket of reactor, add 1mLRuC1₃/CH₃OH solution. By reactor sealing, reactor is raised to 60 DEG C with high-pressure injectionPump is by CO₂Be filled with, until pressure reaches 10.0MPa, maintain super critical condition after 1 hour, cooling, pressure release, unloads still and obtains Ru/MWCNTs catalyst precursors. Then in 80 DEG C of insulating boxs, be dried 4 hours, dried sample is put into the stone of tubular heaterIn English pipe, with hydrogen reducing, at 190 DEG C of reductase 12 h, 350h DEG C of reduction 1h, stops heating, while continuing logical hydrogen cool to room temperature,Obtain Ru/MWCNTs catalyst sample.

Determination of activity result: unit quantity ruthenium, unit interval hydrogen-consuming volume 81.34mmolmin^-1g^-1Ru。

Embodiment 7

Ru/MWCNTs catalyst, preparation method is as follows:

By the CNT of 0.6g (internal diameter 2～5nm, length: 0.5～2 μ m) puts into 50ml with polytetrafluoro linerIn the hanging basket of reactor, add 1mLRuC1₃/CH₃OH solution seals reactor, and reactor is raised to 80 DEG C with high-pressure injectionPump is by CO₂Be filled with, until pressure reaches 10.0MPa, maintain super critical condition after 1 hour, cooling, pressure release, unloads still and obtains Ru/MWCNTs catalyst precursors. Then in 70 DEG C of insulating boxs, be dried 4 hours, dried sample is put into the stone of tubular heaterIn English pipe, with hydrogen reducing, at 210 DEG C of reductase 12 h, 320h DEG C of reduction 1h, stops heating, while continuing logical hydrogen cool to room temperature,Obtain Ru/MWCNTs catalyst sample.

Determination of activity result: unit quantity ruthenium, unit interval hydrogen-consuming volume 76.46mmolmin^-1g^-1Ru。

Embodiment 8

Ru/MWCNTs catalyst, preparation method is as follows:

By the CNT of 0.6g (internal diameter 2～5nm, length: 0.5～2 μ m) puts into anti-with polytetrafluoro liner of 50mlAnswer in the hanging basket of still, add 0.9mLRuC1₃/CH₃OH solution. By reactor sealing, reactor is raised to 80 DEG C with high-pressure injectionPump is by CO₂Be filled with, until pressure reaches 8.0MPa, maintain super critical condition after 0.5 hour, cooling, pressure release, unloads still and obtains Ru/MWCNTs catalyst precursors. Then in 80 DEG C of insulating boxs, be dried 4 hours, dried sample is put into the stone of tubular heaterIn English pipe, with hydrogen reducing, at 200 DEG C of reductase 12 h, 350h DEG C of reduction 1h, stops heating, while continuing logical hydrogen cool to room temperature,Obtain Ru/MWCNTs catalyst sample.

Determination of activity result: unit quantity ruthenium, unit interval hydrogen-consuming volume 75.17mmolmin^-1g^-1Ru。

Comparative example 1

By the CNT of 0.6g (internal diameter 3～5nm, length: 0.5～2 μ m) puts into 50ml with polytetrafluoro linerIn the hanging basket of reactor, add 1mLRuC1₃/CH₃OH solution. By reactor sealing, reactor is raised to 80 DEG C with high-pressure injectionPump is by CO₂Be filled with, until pressure reaches 8.0MPa, maintain super critical condition after 1 hour, cooling, pressure release, unloads still and obtains Ru/MWCNTs catalyst precursors. Then in 80 DEG C of insulating boxs, be dried 4 hours, dried sample is put into the stone of tubular heaterIn English pipe, with hydrogen reducing, at 200 DEG C of reductase 12 h, 350h DEG C of reduction 1h, stops heating, while continuing logical hydrogen cool to room temperature,Obtain Ru/MWCNTs catalyst sample.

Determination of activity result: unit quantity ruthenium, unit interval hydrogen-consuming volume are 66.09mmolmin^-1g^-1Ru。

The performance of the Ru/MWCNTs catalyst to catalyst of the present invention, Ru/AC catalyst and water retting is compared below:

Wherein, the activity rating of catalyst reacts to evaluate with catalysis glucose hydrogenation, and concrete grammar is:

The Ru/MWCNTs catalyst that accurately takes 0.3g reduction-state adds in 150mL high pressure stainless steel cauldron, and to stillInside add 30g Dextrose Monohydrate, 30ml distilled water (glucose solution concentration is 50%), use H after reactor is airtight₂Displacement stillInterior air, three times repeatedly. Temperature in the kettle is risen to 120 DEG C, then fill H₂To still internal pressure be 4.0MPa, control stir speed (S.S.)For 1000r.min^-1, to eliminate the impact of external diffusion. Record H in still₂Pressure temporal evolution is to the change curve of 1.0MPa,And calculate the hydrogen-absorption speed of reaction according to equation for ideal gases, be scaled the hydrogen-consuming volume of unit quantity ruthenium, unit interval, for evaluatingThe hydrogenation activity of catalyst. Because transforming, glucose hydrogenation generates selectively 100% of target product sorbierite nearly, so urgeUnit quantity ruthenium, the unit interval hydrogen-consuming volume of agent can reflect catalyst activity.

1. the present invention is with supercritical CO₂For steeping medium, multi-walled carbon nano-tubes are the prepared Ru/MWCNTs catalysis of carrierAgent is active in the Ru/AC catalyst taking active carbon as carrier in the reaction of hydrogenating glucose to prepare sorbierite.

Ru/AC catalyst activity taking active carbon as carrier is at 40～60(mmolmin^-1g^-1Ru) between, and thisBright catalyst activity is stabilized in 75(mmolmin substantially^-1g^-1Ru) more than, Ru/ prepared by the MWCNTs of other specificationMWCNTs activity is also mostly higher than Ru/AC catalyst. The results detailed in Table 1.

Table 1

Catalyst Ru/MWCNTs(SC) Ru/AC(1) Ru/AC(2)
	Active (mmolmin^-1g^-1Ru） 85.84 47.78 60.13

Note: 1. Ru/MWCNTs(SC), preparation condition is shown in embodiment 4.

2. Ru/AC(1) preparation condition: 100 DEG C, supercritical impregnation 4 hours under 8.0MPa;

Ru/AC(2) preparation condition: 80 DEG C, supercritical impregnation 4 hours under 10.0MPa. (except carrier and first supercritical processing temperatureOutside degree, pressure, time, other preparation condition is same 1.)

2, the relative water retting better effects if of supercritical impregnation:

1. active contrast:

Table 2 supercritical impregnation and the contrast of water retting Ru/MWCNTs catalyst activity

Note: Ru/CNT-I (SC): multi-walled carbon nano-tubes is carrier, internal diameter 2～5nm, length: 0.5～2 μ m, prepares barPart is with embodiment 4;

Ru/CNT-II (SC): multi-walled carbon nano-tubes is carrier, internal diameter 3～5nm, length: 0.5～2 μ m, other same Ru/CNT-Ⅰ(SC)。

Ru/CNT-Ⅰ（H₂O): multi-walled carbon nano-tubes is carrier, internal diameter 2～5nm, length: 0.5～2 μ m; (0.6g carbonNanotube and 0.09gRuCl₃·xH₂O adds 4ml water to leave standstill dipping 6 hours in beaker)

Ru/CNT-II（H₂O): multi-walled carbon nano-tubes is carrier, internal diameter 3～5nm, length: 0.5～2 μ m, other are sameRu/CNT-Ⅰ（H₂O）。

As seen from the above table, the active contrast of the sample of first supercritical processing and water retting (ruthenium load capacity is close), first supercritical processingSample activity larger.

2. active component decentralization contrast:

Fig. 1,2 is respectively catalyst (Ru/CNT-I (SC) and the Ru/ of supercritical carbon dioxide treatment and water treatmentCNT-Ⅰ(H₂O) TEM figure), from TEM figure, first supercritical processing is less than the granularity of water retting sample active component ruthenium,Good dispersion degree.

3. stability contrast:

Supercritical CO₂The loss of Ru/MWCNTs catalyst (contrast specimen in use is with the table 2) ruthenium of dipping preparation is less, saysBright in supercritical medium the adsorption strength of ruthenium larger. Measure prepared with inductively coupled plasma atomic emission (ICP) methodThe stability of ruthenium Pd/carbon catalyst. Reacted glucose solution is settled to 100ml, measures Ru content wherein with ICP method.Ruthenium in this glucose solution is to run off from catalyst in course of reaction. Concrete outcome is in table 3.

Table 3

Adopt ultrasonic wave to process (supersonic frequency 40KHz, 50 DEG C, processing time 120min) to above-mentioned catalyst, fromThe TEM figure of ultrasonic wave sample after treatment is visible, and the ruthenium particle of water retting sample scatters and disappears obviously.

Claims

1. a preparation method for Ru/MWCNTs catalyst, is characterized in that, is 2-5nm by 0.6g internal diameter, external diameter < 8nm,Length is that the CNT of 0.5-2 μ m is put into the hanging basket of 50ml with the reactor of polytetrafluoro liner, adds 1mlRuCl₃/CH₃OH solution; By reactor sealing, reactor be raised to 80 DEG C with high pressure syringe pump by CO₂Be filled with, until pressure reaches 8MPa, maintainAfter super critical condition 1 hour, cooling, pressure release, unloads still and obtains Ru/MWCNTs catalyst precursors; Then in 80 DEG C of insulating boxsDry 4 hours, dried sample was put into the quartz ampoule of tubular heater, with hydrogen reducing, and at 200 DEG C of reductase 12s hour,350 DEG C are reduced 1 hour, stop heating, while continuing logical hydrogen_cooling to room temperature, obtain Ru/MWCNTs catalyst.