CN1321055C

CN1321055C - Method for producing hydrogen-rich recombined gas by means of methanol autothermal recombination reaction

Info

Publication number: CN1321055C
Application number: CNB200410091304XA
Authority: CN
Inventors: 李秋煌; 黄建良; 林嘉靖
Original assignee: Industrial Technology Research Institute ITRI
Current assignee: Industrial Technology Research Institute ITRI
Priority date: 2004-11-22
Filing date: 2004-11-22
Publication date: 2007-06-13
Anticipated expiration: 2024-11-22
Also published as: CN1778667A

Abstract

The invention relates to a catalyst which can catalyze methanol to carry out steam reforming or self-heating reforming reaction (ATR), and methanol, air and steam are fed and converted into hydrogen-rich reformed gas containing hydrogen, carbon monoxide and carbon dioxide through reforming reaction. The catalyst comprises a mixed oxide of cerium oxide and zirconium oxide as a carrier, and platinum supported on the mixed oxide. The catalyst catalyzes the conversion of a feed containing methanol, steam and air into a hydrogen-rich reformate gas containing hydrogen, carbon monoxide and carbon dioxide by an autothermal reforming reaction.

Description

Produce the method for hydrogen-enriched recombinant gas by the methanol self-heating recombining reaction

Technical field

The invention relates to a kind of catalyzer, but its catalysis methanol carries out the steam reorganization or claims autothermal recombining reaction (Autothermal reforming reaction, be called for short ATR), convert methyl alcohol, air and water vapour charging to contain hydrogen, carbon monoxide and carbonic acid gas hydrogen-enriched recombinant gas via recombining reaction.

Background technology

(polymer electrolyte fuel cell PEFC) very likely will be used for fixation type family power generation system and electromobile to the macromolecule membrane fuel cell future, and the required fuel of supply PEFC system is the hydrogen-rich gas (H that CO concentration is lower than 20ppm ₂Concentration＞35%).The hydrogen-enriched recombinant gas that general hydrocarbon polymer produces via recombining reaction, its CO concentration is about 4～15%, must be via water transfer reaction (Water-gas shift, WGS) as far as possible the CO concentration of hydrogen-enriched recombinant gas is reduced to below 1%, via selective oxidation reaction (Preferential oxidation reaction) or methanation reaction (Methanation reaction) series connection selective oxidation reaction CO concentration is reduced to below the 100ppm more afterwards, even be low to moderate below the 20ppm.In numerous fuel, be suitable as the fuel of Portable PEFC power generation system most with methyl alcohol.Methyl alcohol is liquid fuel, and the energy resource density height of unit volume is easy to carry, and methyl alcohol sulfur compound not, and the recombining reaction temperature is low, all helps the purpose of fuel reformer system miniaturization.Tradition methyl alcohol reformer all adopts the steam recombining reaction, and design with the autothermal recombining reaction bright lacking.The catalyzer of general methanol self-heating recombining reaction serves as main the composition with copper-zinc-aluminium mostly, outside add other metal such as magnesium, potassium, zirconium, calcium etc. again, it is not good that yet the shortcoming of copper-zinc-Al catalysts maximum is heat-resistant quality, because the thermostability of copper itself is not good.When the temperature of reaction height, copper can reduce because of sintering is active, and particularly under the ATR reaction conditions, copper-zinc-aluminium catalyst heat-resistant quality is poorer.

The PEFC power generation system that with methyl alcohol is fuel is to be best suited for the portable purposes.And in order to use this field, it is little that the methyl alcohol reformer should have system bulk, the advantage that start time is short.And the ATR recombining reaction obviously is better than the steam recombining reaction in this respect.

Outside the conditions such as it is little that methyl alcohol ATR reformer must possess system bulk, and start time is short, the concentration that methyl alcohol remains in hydrogen-enriched recombinant gas must be lower than below the 5000ppm, and lower better, because remaining methyl alcohol can suppress the battery set electrode activity of such catalysts.Methanol concentration is lower than 5000ppm in the hydrogen-enriched recombinant gas in order to make, and the methanol conversion of ATR reaction is higher than more than 98%.In order to reach this purpose, must improve the ATR temperature of reaction or reduce the space flow speed that ATR reacts, the latter runs counter to the requirement of reformer volume miniaturization, and the former (raising temperature of reaction) is unfavorable for existing copper-zinc-Al catalysts.

Company such as Nissan Motor or Mitsubishi once developed some methyl alcohol ATR catalysts that contain precious metal, its catalyzer is a main ingredient with Pt-Zn or Pd-Zn, these catalyzer have the space that is modified again, for example the CO concentration in the hydrogen-enriched recombinant gas that is produced is higher than 10%, and shortcomings such as catalyst strength is poor, easy efflorescence.

Summary of the invention

Purpose of the present invention is promptly in a kind of methyl alcohol ATR catalyst for reaction of research and development, it has active height and the high characteristic of heat-resistant quality, both can meet the little requirement of methyl alcohol ATR reformer volume, also be beneficial to the practicality of methyl alcohol ATR reformer because of the high stability of catalyzer.

The present invention be with cerium oxide and zirconic mixed oxide as carrier, a platiniferous presoma is carried on this mixed oxide, through super-dry, calcining and make platinum/cerium Zr mixed oxide (Pt/CeO ₂-ZrO ₂) catalyzer.

The Pt/CeO of the present invention's exploitation ₂-ZrO ₂Catalyzer, it is except the energy catalysis methanol carries out the ATR reaction, and it has good heat-resistant quality.Simultaneously, Pt/CeO ₂-ZrO ₂CO concentration in the hydrogen-enriched recombinant gas that catalysis methanol ATR reaction produces is lower than 8%, and water transfer catalysts can convert it into hydrogen easily reduces to below 1% CO concentration.And reduce to 1% when following when the CO of recombinant gas concentration, can the CO concentration of recombinant gas be reduced to below the 100ppm via methanation or selective oxidation reaction.

Embodiment

The present invention discloses a kind of method of producing hydrogen-enriched recombinant gas by the methanol self-heating recombining reaction, comprise methyl alcohol, water and oxygen are carried out the autothermal recombining reaction in the presence of 200～600 ℃ and catalyzer, and generation hydrogen, carbon monoxide and carbonic acid gas, it is characterized in that this catalyzer comprises cerium oxide and the zirconic mixed oxide as carrier, and be carried on the platinum of this mixed oxide.

Preferable, this mixed oxide comprises 25～75% cerium oxide, is benchmark with the weight of this mixed oxide.

Preferable, this catalyzer comprises 0.1～5% platinum, is benchmark with the weight of this mixed oxide.

Preferable, wherein this water is 1～3 to the mol ratio of methyl alcohol, and oxygen is 0.1～0.8 to the mol ratio of methyl alcohol.

One method that is suitable for preparing catalyzer of the present invention comprises the following step:

A) make this mixed oxide by wet impregnation (incipient wetness impregnation) just with an amount that contains Pt ionic aqueous solution impregnation cerium oxide and zirconic mixed oxide and this aqueous solution; And

B) heat the mixed oxide of the just wet impregnation of this quilt and make in this aqueous solution composition in fact only the Pt ion be attached on this metal oxide.

Preferable, make this mixed oxide just be soaked with 0.1～5.0% Pt ion wet containing in the amount of this aqueous solution of step a), be benchmark with the weight of this mixed oxide.

So-called just wet impregnation is before carrier is by impregnation Pt ion, measures the water-intake rate (ml/g) of carrier earlier, presses an amount of Pt aqueous metal salt volume of carrier amount preparation afterwards.In stirring the carrier process, this aqueous solution is dropwise added in the container that fills carrier, and the aqueous solution that adds can absorb by suppressed by vector immediately, treat that all aqueous solution add promptly to finish in finishing that this moment, carrier still presented the slightly moistening powdered form in surface.

Preferable, be contained in the mixed oxide of 100～150 ℃ of these quilts of drying wet impregnation just and in 400～600 ℃ of these exsiccant mixed oxides of calcining in the heat packs of step b), with 450～550 ℃ for better.

Another method that is suitable for preparing catalyzer of the present invention comprises the following step:

A) contain Pt ionic aqueous solution impregnation cerium oxide and zirconic mixed oxide with one;

B) adding a precipitation agent makes the Pt ion be deposited on this mixed oxide with metal form in this aqueous solution;

C) with filter type separating step B) mixture and obtain the mixed oxide that this precipitation has the Pt metal; And

D) heat the mixed oxide that this precipitation has the Pt metal.

Preferable, step B) precipitation agent is to be selected from diamine (Hydrazine), formaldehyde.

Preferable, in steps A) the amount of this aqueous solution make that this mixed oxide is precipitated 0.1～5.0% Pt arranged, be benchmark with the weight of this mixed oxide.

Preferable, in step D) heat packs be contained in that 100～150 ℃ of these precipitations of drying have the mixed oxide of Pt metal and in 400～600 these exsiccant mixed oxides of calcining, with 450～550 ℃ for better.

Description of drawings

Fig. 1 a shows the known copper-zinc-product density of hydrogen % of Al catalysts catalysis methanol ATR reaction of comparative example 1 and the relation of the temperature in of reactant gases, and wherein black Diamond spot is represented test result for the first time, reaches the open diamonds point expression result of test for the second time.

Fig. 1 b shows the known copper-zinc-products C O concentration % of aluminium catalyst catalysis methanol ATR reaction of comparative example 1 and the relation of the temperature in of reactant gases, and wherein black Diamond spot is represented test result for the first time, reaches the open diamonds point expression result of test for the second time.

The relation of the product density of hydrogen % of the commercial MDC-3 catalyst methyl alcohol ATR reaction of Fig. 2 a demonstration comparative example 2 and the temperature in of reactant gases, wherein black Diamond spot is represented test result for the first time, the black form point is represented the result of test for the second time, and black triangle form point is represented the result that tests for the third time.

The relation of the products C O concentration % of the commercial MDC-3 catalyst methyl alcohol ATR reaction of Fig. 2 b demonstration comparative example 2 and the temperature in of reactant gases, wherein black Diamond spot is represented test result for the first time, the black form point is represented the result of test for the second time, and black triangle form point is represented the result that tests for the third time.

Fig. 3 a shows the known Pd-Zn/Al of comparative example 3 and 4 ₂O ₃And Pt-Zn/Al ₂O ₃The relation of the product density of hydrogen % of catalyst methyl alcohol ATR reaction and the temperature in of reactant gases, wherein black Diamond spot is represented Pd-Zn/Al ₂O ₃The result of catalyzer, and the black form point is represented Pt-Zn/Al ₂O ₃The result of catalyzer.

Fig. 3 b shows the known Pd-Zn/Al of comparative example 3 and 4 ₂O ₃And Pt-Zn/Al ₂O ₃The relation of the products C O concentration % of catalyst methyl alcohol ATR reaction and the temperature in of reactant gases, wherein black Diamond spot is represented Pd-Zn/Al ₂O ₃The result of catalyzer, and square hollow point expression Pt-Zn/Al ₂O ₃The result of catalyzer.

Fig. 4 a shows the Pt/CeO of the embodiment of the invention 1 ₂-ZrO ₂The relation of the product density of hydrogen % of catalyst methyl alcohol ATR reaction and the temperature in of reactant gases, wherein black Diamond spot is represented test result for the first time, the black form point is represented the result of test for the second time, and deceives the triangle form point and represent the result that tests for the third time.

Fig. 4 b shows the Pt/CeO of the embodiment of the invention 1 ₂-ZrO ₂The relation of the products C O concentration % of catalyst methyl alcohol ATR reaction and the temperature in of reactant gases, wherein black Diamond spot is represented test result for the first time, the black form point is represented the result of test for the second time, and deceives the triangle form point and represent the result that tests for the third time.

Fig. 5 shows the Pt/CeO with the embodiment of the invention 1 ₂-ZrO ₂Catalyzer is in the long-time test result of 420 ℃ of catalysis methanol ATR reactions, and wherein black Diamond spot is represented the density of hydrogen % in the product, and the black form point is represented the CO concentration % in the product.

Embodiment

The present invention will further be understood by the following example, and these embodiment but not are used to limit the scope of the invention as illustrative purposes only.

Comparative example 1

Take by weighing 151.02g Cu (NO ₃) ₂.3H ₂O, 214.31g Al (NO ₃) ₃.9H ₂O and 71.0gZn (NO ₃) ₂.6H ₂O is dissolved in the deionized water of 3000ml.Under stirring at room, splashing into 28% ammoniacal liquor to pH value is 7.5.After the stirring at room 2 hours, after filtration, washing, 120 ℃ of dryings (24 hours) were calcined 5 hours for 500 ℃, and promptly getting the weight proportion of composing is CuO: ZnO: Al ₂O ₃=39: 15.3: 45.7 Cu/Al ₂O ₃-ZnO catalyst.The silicon-dioxide that adds 1 weight % again is as cakingagent, with Cu/Al ₂O ₃-ZnO catalyst high pressure is played ingot, breaks into the pellet type catalyst of 16～20 meshes (mesh) again into pieces.

Comparative example 2

To buy the commercial catalyst that code name is MDC-3, through breaking into the pellet type catalyst of 16～20 meshes into pieces from Sud-Chemi company (Germany).The main composition of MDC-3 catalyzer is CuO: ZnO: Al ₂O ₃=40～44: 44～50: 7～13 (weight ratio).

Comparative example 3

Get Zn (NO ₃) ₂.6H ₂O (95%) 5.3g and the Palladous nitrate that contains palladium 1.8g are dissolved in the deionized water of 66ml, the alumina powder that slowly adds 60g again, afterwards again through 120 ℃ of dryings (24 hours), afterwards through 300 ℃ of calcinings (5 hours), the silicon-dioxide that adds 1 weight % is again played ingot as the cakingagent high pressure, breaks into the particulate state Pd-Zn/Al of 16～20 meshes again into pieces ₂O ₃Catalyzer.

Comparative example 4

Get Zn (NO ₃) ₂.6H ₂O (95%) 2.74g and the platinum nitrate that contains platinum 1.8g are dissolved in the deionized water of 66ml, the alumina powder that slowly adds 60g again, afterwards again through 120 ℃ of dryings (24 hours), 300 ℃ of calcinings (3 hours), the silicon-dioxide that adds 1 weight % is again played ingot as the cakingagent high pressure, breaks into the particulate state Pt-Zn/Al of 16～20 meshes again into pieces ₂O ₃Catalyzer.

Embodiment 1

With cerium oxide and zirconia mixed oxide powder is carrier, wherein cerium oxide weight is 75 weight %, utilizing just wet impregnation method will contain platinum nitrate solution again contains and is immersed on the carrier, comprise in the aqueous solution of the platinum nitrate melt into 100ml that will contain platinum 5g, slowly add on the carrier of 250g again, through 120 ℃ of dryings (24 hours), through 500 ℃ of calcinings (2 hours), make the Pt/CeO that platinum content is 2 weight % afterwards again ₂-ZrO ₂Catalyzer.The silicon-dioxide that adds 1 weight % again is as cakingagent, with Pt/CeO ₂-ZrO ₂The catalyzer high pressure is played ingot, breaks into the pellet type catalyst of 16～20 meshes again into pieces.

Utilize conventional fixed bed reactive system detecting catalyst catalysis methanol ATR reactive activity, get above-mentioned particulate state (16～20 mesh) catalyzer and insert in the crystal reaction tube of 2.2 centimeters of internal diameters, utilize the temperature in of electrothermal oven control reactant gases.Reactant gases has H ₂O/ methyl alcohol mol ratio is 1.3 or 1.8, oxygen/methyl alcohol mol ratio is 0.25.The reactant gases total flux is 4L/min.Catalyst volume is 6.3ml.

Fig. 1～5th, the test result that the catalyst reactant gases of above comparative example and embodiment preparation carries out methyl alcohol ATR reaction.The experimental result of Fig. 1 a and 1b shows known CuZnAl catalyst (comparative example 1), is repeating methyl alcohol ATR reaction process, and it descends rapidly to methanol conversion, shows that the thermotolerance of this catalyzer is also bad.As for the MDC-3 commercial catalyst, in repeating methyl alcohol ATR reaction process, this catalyst degradation speed is obviously than the CuZnAl catalyst slow (Fig. 2 a and 2b) of comparative example 1, and CO and density of hydrogen sum total still have the decline phenomenon in recombinant gas but this catalyzer produces.In addition, this catalyzer is under operate continuously in 24 hours, and the catalyzer efflorescence is serious, only remains the catalyzer of about 50% volume at last.

Pt-Zn/Al as for comparative example 3 and 4 ₂O ₃And Pd-Zn/Al ₂O ₃Catalyzer reacts highly active characteristic (Fig. 3 a), the CO concentration of the hydrogen-enriched recombinant gas that this catalyzer produces is unfavorable for the removal of CO concentration in the follow-up hydrogen-enriched recombinant gas obviously than higher (＞10%) (Fig. 3 b) though have catalysis methanol ATR.Have embodiment 1 synthetic Pt/CeO only ₂-ZrO ₂In the stability that repeats methyl alcohol ATR reaction process than higher, shown in Fig. 4 a and 4b.And this embodiment 1 catalyzer is in the durable test process of carrying out aforementioned methyl alcohol ATR reaction with 420 ℃, and the hydrogen of the hydrogen-enriched recombinant gas that catalyzer produces and CO concentration is all very stable (Fig. 5) haply, shows this Pt/CeO ₂-ZrO ₂The thermally-stabilised catalyzer that obviously is better than traditional copper-zinc-aluminium, and the CO concentration of the hydrogen-enriched recombinant gas that is produced is lower than 10%.

The present invention is described in, and person skilled in the art scholar still can make multiple variation and the modification that does not break away from following claim.

Claims

1. A method for producing hydrogen-rich recombination gas by means of methanol autothermal recombination reaction, comprising carrying out autothermal recombination reaction with methanol, water and oxygen at 200-600°C and in the presence of a catalyst to produce hydrogen, carbon monoxide and carbon dioxide , characterized in that the catalyst comprises a mixed oxide of ceria and zirconia as a carrier, and platinum supported on the mixed oxide;

Wherein the mixed oxide contains 25-75% cerium oxide, based on the weight of the mixed oxide; the catalyst contains 0.1-5% platinum, based on the weight of the mixed oxide.

2. The method according to claim 1, wherein the molar ratio of water to methanol is 1-3, and the molar ratio of oxygen to methanol is 0.1-0.8.

3. The method of claim 1, wherein the catalyst is prepared by a method comprising the steps of:

a) impregnating the mixed oxide of ceria and zirconia with an aqueous solution containing Pt ions in such an amount that the mixed oxide is impregnated with incipient wetness; and

b) heating the mixed oxide impregnated with incipient wetness such that substantially only Pt ions of the components in the aqueous solution adhere to the metal oxide.

4. The method of claim 3, wherein the amount of the aqueous solution in step a) is such that the mixed oxide is impregnated with 0.1-5.0% Pt ions based on the weight of the mixed oxide by incipient wetness.

5. The method of claim 3, wherein the heating in step b) comprises drying the mixed oxide impregnated with incipient wetness at 100-150°C and calcining the dried mixed oxide at 400-600°C.

6. The method as claimed in claim 5, wherein the calcination is performed at 450-550°C.