CN101474563B - Preparation method of catalyst for hydrogen production from methanol-steam reforming - Google Patents

Abstract

The invention discloses a method for preparing a catalyst for hydrogen production from methanol steam reforming, comprising the following steps: a. by adopting cocurrent coprecipitation method, dissolving copper nitrate, zinc nitrate and aluminum nitrate in the distilled water and to undergo cocurrent dripping and coprecipitation with the sodium carbonate solution, fully stirring, controlling thePH value to be about 7.0, and leaching, drying and baking after reaction to produce the catalyst Cu/ZnO/Al2O3; b. adding the obtained catalyst Cu/ZnO/Al2O3 into the mixed solution of zirconium oxychloride and cerium nitrate and stirring continuously to produce a suspension, dripping the sodium carbonate solution, controlling the PH value to be 7.0, and then leaching, washing, drying and baking after ageing to produce the product. In the invention, a layer of CeO2-ZrO2 is coated on the surface of the catalyst Cu/ZnO/Al2O3 so as to stabilize the oxygen species in the copper component on the catalyst surface, accelerate the dissociation absorption of the water and improve the activity and stability of the catalyst for hydrogen production from methanol steam reforming.

Description

The Preparation of catalysts method that is used for hydrogen production from methanol-steam reforming

Technical field

The present invention relates to a kind of Preparation of catalysts method that is used for hydrogen production from methanol-steam reforming, relate to a kind of modification Cu/ZnO/Al that is used for hydrogen production from methanol-steam reforming in particular ₂O ₃The Preparation of catalysts method.

Background technology

Methanol steam (MSR) hydrogen production reaction battery that acts as a fuel of reforming, the alternative hydrogen source of Proton Exchange Membrane Fuel Cells (PEMFC) particularly, has cleaning, efficiently, advantage such as convenient transportation, generally use noble metal catalyst at present, but the price limit of noble metal catalyst costliness generally applying of steam reformation of methanol to produce hydrogen.Copper catalyst is because cheap, high advantages such as catalytic activity gain great popularity in recent years, but because catalyst such as CuZnAl and CuCr easy inactivation in the hydrogen production from methanol-steam reforming course of reaction, and shortcomings such as generation that a certain amount of CO accessory substance is arranged have limited the hydrogen source that copper catalyst directly applies to PEMFC.Improving the stability of copper-based catalysts, reduce the generation of CO, is to improve the important topic that copper catalyst is used for steam reformation of methanol to produce hydrogen industry at present.Document shows that more and more evidences is supported Cu ⁺Species are even more important in catalytic reaction.In reaction system, feed the gas of a spot of oxidisability, for example CO ₂Or O ₂Just can significantly improve Cu activity of such catalysts and stability.By adopting model catalyst that the catalytic activity result of study is also further shown, exist corresponding relation between the oxygen species of activity of such catalysts with the copper surface, so the oxygen species on stabilized copper surface become the core content that improves copper catalyst.

Summary of the invention

Technical problem to be solved by this invention is at Cu/ZnO/Al ₂O ₃Catalyst surface parcel one deck CeO ₂-ZrO ₂Superficial layer is accelerated the absorption of dissociating of water with the oxygen species of rugged catalyst surface copper component, thereby further improves the activity of hydrogen production from methanol-steam reforming of catalyst and stable.

Technical solution of the present invention: a kind of Preparation of catalysts method that is used for steam reformation of methanol to produce hydrogen comprises the following steps:

A. adopt and flow coprecipitation method to prepare catalyst, copper nitrate, zinc nitrate and aluminum nitrate are dissolved in the distilled water than Cu: Zn: Al=40.0～47.5%: 40.0～47.5%: 5～20% by the molar content of metal atom, at 59～61 ℃ and 1mol.L ^-1Sodium carbonate liquor and drip add co-precipitation, fully stir in the precipitation process, and keep the pH value about 7.0, react after 1 hour, suction filtration, filter cake at 120 ℃ of dry 12h, make Cu/ZnO/Al at 350 ℃ of roasting 4h after spending deionised water 6～7 times at last ₂O ₃Catalyst;

B. the molar content of pressing the metal atom adds the Cu/ZnO/Al of step a preparation in the mixed liquid of zirconium oxychloride and cerous nitrate than Cu: Zn: Al: Zr: Ce=37.7～43.2%: 37.7～43.2%: 4.5～19.0%: 4.7～10.4%: 0.9～2.6% ₂O ₃Catalyst also constantly stirs to form and poises liquid, slowly drips the sodium carbonate liquor of 1mol.L-1 then under 60 ℃, remains on 7.0 until the pH value of solution value, suction filtration behind the ageing 2h, and washing extremely detects less than Cl ^-Till, at last at 120 ℃ of dry 12h, and, obtain the final catalyst that is used for steam reformation of methanol to produce hydrogen in 350 ℃ of following roasting 4h.

The beneficial effect of the invention, though about the Cu catalyst to the existing big quantity research of the absorption of methyl alcohol, out in the cold always about water in the research of absorption of Cu catalyst surface and activation process.The inventor finds ZrO by catalyst characterization ₂The component adsorbed water of can dissociating effectively forms surface hydroxyl, and it can be directly and the ADSORPTION STATE methyl alcohol generation CO that reacts ₂And hydrogen, thereby avoided the consumption of copper surface oxygen species and stablized the oxygen species of catalyst surface.In addition, introduce rare-earth additive and not only catalyst structure is played effect stable and that optimize in catalyst, itself and other component of catalyst have very strong cooperative effect, thereby further improve catalytic activity.Therefore, the present invention is with Cu/ZnO/Al ₂O ₃Catalyst is a basic point, adopts sol-gal process to contain the ZrO of rare earth at the catalyst surface parcel ₂Film, surperficial oxygen species that not only can stabilized copper stop the reunion of copper particle in reduction and course of reaction, and ZrO ₂Film also can activate in advance to methyl alcohol and water component, form surface hydroxyl and surperficial methoxyl group, be diffused into copper zirconium near interface by the overflow effect then and react, thereby improve activity of such catalysts, the CO accessory substance that this external copper zirconium interfacial reaction is produced is seeing through ZrO ₂The outside diffusion process of film in, can and ZrO ₂Surface hydroxyl and adsorbed water generation secondary response generate CO ₂Thereby further reduce CO ₂The generation of accessory substance improves catalyst activity and stability thereby reach, and suppresses CO ₂The purpose that generates.

The specific embodiment

Below by embodiment the present invention is described in further detail, a kind of Preparation of catalysts method that is used for steam reformation of methanol to produce hydrogen comprises the following steps:

A. adopt and flow coprecipitation method to prepare catalyst, copper nitrate, zinc nitrate and aluminum nitrate are dissolved in the distilled water than Cu: Zn: Al=40.0～47.5%: 40.0～47.5%: 5～20% by the molar content of metal atom, at 59～61 ℃ and 1mol.L ^-1Sodium carbonate liquor and drip add co-precipitation, fully stir in the precipitation process, and keep the pH value about 7.0, react after 1 hour, suction filtration, filter cake at 120 ℃ of dry 12h, make Cu/ZnO/Al at 350 ℃ of roasting 4h after spending deionised water 6～7 times at last ₂O ₃Catalyst;

B. the molar content of pressing the metal atom adds the Cu/ZnO/Al of step a preparation in the mixed liquid of zirconium oxychloride and cerous nitrate than Cu: Zn: Al: Zr: Ce=37.7～43.2%: 37.7～43.2%: 4.5～19.0%: 4.7～10.4%: 0.9～2.6% ₂O ₃Catalyst (granularity＞200 orders) also constantly stirs to form and poises liquid, slowly drips the sodium carbonate liquor of 1mol.L-1 then under 60 ℃, remains on 7.0 until the pH value of solution value, suction filtration behind the ageing 2h, and washing extremely detects less than Cl ^-Till, at last at 120 ℃ of dry 12h, and, obtain the final catalyst that is used for steam reformation of methanol to produce hydrogen in 350 ℃ of following roasting 4h.

Embodiment 1

A. adopt and flow coprecipitation method to prepare catalyst, by the molar content of metal atom than Cu: Zn: Al=45.0: copper nitrate, zinc nitrate and aluminum nitrate be dissolved in the distilled water in 45.0: 10.0, at 59～61 ℃ and 1mol.L ^-1Sodium carbonate liquor and drip add co-precipitation, fully stir in the precipitation process, and keep the pH value about 7.0, react after 1 hour, suction filtration, filter cake at 120 ℃ of dry 12h, make Cu/ZnO/Al at 350 ℃ of roasting 4h after spending deionised water 6～7 times at last ₂O ₃Catalyst;

B. the molar content of pressing the metal atom is than Cu: Zn: Al: Zr: Ce=40.9: 40.9: 9.2: 7.2: 1.8 added the Cu/ZnO/Al of step a preparation in the mixed liquid of zirconium oxychloride and cerous nitrate ₂O ₃Catalyst (granularity＞200 orders) and continuous stirring form and poise liquid, slowly drip 1mol.L then under 60 ℃ ^-1Sodium carbonate liquor, remain on 7.0 until the pH value of solution value, suction filtration behind the ageing 2h, washing is to detecting less than Cl ^-Till, at last at 120 ℃ of dry 12h, and, obtain final catalyst in 350 ℃ of following roasting 4h.Then with the catalyst compressing tablet and to be crushed to the 20-40 order standby.

The catalyst activity evaluation is carried out in atmospheric fixed bed flowing reactive system:

With 0.5g catalyst (40～60 order) with evenly mix with volume quartz sand after the reactor flat-temperature zone of packing into, during activity rating earlier with 5%H ₂/ N ₂Gaseous mixture (flow 80mL/min) feeds reactor, 2 ℃/min temperature programming to 250 ℃ reduction activation catalyst 8h, then the reacting furnace temperature is dropped to the setting reaction temperature, switch nitrogen (flow 30mL/min), nitrogen stream is introduced reaction system with the mixed liquor of water and methyl alcohol and is begun reaction.Be reflected at and set reaction temperature and stablize the analysis of 2h post-sampling, the reaction tube gas that comes out is detected by thermal conductivity detector (TCD) (TCD) through condenser cooling back earlier, with the line data processing of going forward side by side of work station control sampling process.Reaction condition: H ₂O/CH ₃OH=1.1/1 (mol ratio), WHSV=3.60h ^-1.g ^-1, T=230 ℃, P=0.1MPa, evaluation result sees Table 1.

Table 1

CO ₂Selectivity (down together): $S_{C{O}_2}=y_{C{O}_2}/(y_{\mathrm{CO}}+y_{{\mathrm{CO}}_2})$

Embodiment 2

Method for preparing catalyst and activity rating method are with embodiment 1, and the molar content of metallic atom is than being Cu: Zn: Al: Zr: Ce=37.7: 37.7: 19.0: 4.7: 0.9.Reaction condition: H ₂O/CH ₃OH=1.1/1 (mol ratio), WHSV=3.60h ^-1.g ^-1, T=230 ℃, P=0.1MPa, evaluation result sees Table 2.

Table 2

Embodiment 3

Method for preparing catalyst and activity rating method are with embodiment 1, and the molar content of metallic atom is than being Cu: Zn: Al: Zr: Ce=43.2: 43.2: 4.5: 7.3: 1.8.Reaction condition: H ₂O/CH ₃OH=1.1/1 (mol ratio), WHSV=3.60h ^-1.g ^-1, T=230 ℃, P=0.1MPa, evaluation result sees Table 3.

Table 3

Embodiment 4

Method for preparing catalyst and activity rating method are with embodiment 1, and the molar content of metallic atom is than being Cu: Zn: Al: Zr: Ce=39.1: 39.1: 8.8: 10.4: 2.6.Reaction condition: H ₂O/CH ₃OH=1.1/1 (mol ratio), WHSV=3.60h ^-1.g ^-1, T=230 ℃, P=0.1MPa, evaluation result sees Table 4.

Table 4

By embodiment 1～4 as can be known, preparation method of the present invention is simple, easy operating, and catalyst performance repeatability is relatively good, realizes the industry amplification easily; Catalyst of the present invention is with relatively inexpensive Cu/ZnO/Al ₂O ₃As main body, at area load CeO ₂-ZrO ₂Shell has improved CeO ₂And ZrO ₂Utilization rate, reduced the catalyst cost; The present invention compares Cu/ZnO/Al ₂O ₃Catalyst, activity of such catalysts and stability all significantly increase, and the content of accessory substance CO all obviously reduces.Generally speaking the present invention is a kind of CeO ₂-ZrO ₂The Cu/ZnO/Al of shell modification ₂O ₃Catalyst, catalyst of the present invention are used for the methanol steam reforming reaction, and mild condition has high reaction activity and high, and accessory substance is less.

Described content only is the basic explanation of the present invention under conceiving, and according to any equivalent transformation that technical scheme of the present invention is done, all should belong to protection scope of the present invention.

Claims (1)

1. a Preparation of catalysts method that is used for steam reformation of methanol to produce hydrogen comprises the following steps:

A. adopt and flow coprecipitation method to prepare catalyst, copper nitrate, zinc nitrate and aluminum nitrate are dissolved in the distilled water than Cu: Zn: Al=40.0～47.5%: 40.0～47.5%: 5～20% by the molar content of metal atom, at 59～61 ℃ and 1mol.L ^-1Sodium carbonate liquor and drip add co-precipitation, fully stir in the precipitation process, and keep the pH value 7.0, react after 1 hour, suction filtration, filter cake at 120 ℃ of dry 12h, make Cu/ZnO/Al at 350 ℃ of roasting 4h after spending deionised water 6～7 times at last ₂O ₃Catalyst;

B. the molar content of pressing the metal atom adds the Cu/ZnO/Al of step a preparation in the mixed liquid of zirconium oxychloride and cerous nitrate than Cu: Zn: Al: Zr: Ce=37.7～43.2%: 37.7～43.2%: 4.5～19.0%: 4.7～10.4%: 0.9～2.6% ₂O ₃Catalyst also constantly stirs the formation suspension, slowly drips 1mol.L then under 60 ℃ ^-1Sodium carbonate liquor, remain on 7.0 until the pH value of solution value, suction filtration behind the ageing 2h, washing is to detecting less than Cl ^-Till, at last at 120 ℃ of dry 12h, and, obtain the final catalyst that is used for steam reformation of methanol to produce hydrogen in 350 ℃ of following roasting 4h.