CN102974362B - Catalyst for hydrogen production by catalytic reforming with biological oil and preparation method - Google Patents

Abstract

The invention relates to a catalyst for catalytic hydrogen production from bio-oil and a preparation method thereof, comprising a catalyst active component and a catalyst carrier, and the catalyst active component and weight percentage are respectively: Ni is 10-15wt%; Mo is 5- 13wt%; Fe is 5-10wt%; the rest is divided into attapulgite and sepiolite mixed clay ore catalyst carrier. The advantage of the present invention is that attapulgite and sepiolite clay ore with large specific surface area, strong adsorption and catalytic functions, cheap and easy to obtain are used as the catalyst carrier, and the catalytic active component is a composite group of nickel, molybdenum and iron. Separation, so that bio-oil molecules are cracked and chain-broken into low-molecular hydrocarbons and high-quality syngas with high hydrogen content. The catalyst is simple to prepare, strong in strength, strong in catalytic activity and reproducible, and can be used not only for bio-oil reforming to produce hydrogen, but also for direct catalytic gasification of biomass to produce hydrogen.

Description

Catalyst and preparation method for hydrogen production by catalytic reforming of bio-oil

technical field

The invention relates to a bio-oil catalytic reforming hydrogen production catalyst and a preparation method thereof, that is, a method for preparing a catalyst for high-quality gas fuel by using bio-oil catalytic reforming hydrogen production from biomass cracking.

Background technique

The use of biomass to produce hydrogen is not only an effective use of abundant renewable resources, but also one of the effective ways to finally solve the huge environmental pollution caused by global fossil fuels. my country's fossil fuel resources are short and biomass resources are very rich. How to clean it cheaply? The efficient conversion of biomass into hydrogen fuel, the core power of the future hydrogen energy society, is of great significance to the sustainable development of our country. Biomass is highly dispersed and low in energy density, which determines the high cost of collection and transportation and poor economics in the process. Rapid pyrolysis of biomass can produce bio-oil with high energy density, which can be produced in a dispersed manner and then processed in a centralized manner. At present, rapid pyrolysis oil production technology is close to industrialization. Because of its composition characteristics, bio-oil can be produced by steam catalytic reforming to produce hydrogen, which is a new way of bio-oil utilization.

The current research on bio-oil hydrogen production mainly includes: development of new pyrolysis hydrogen production reactors, research on catalytic reforming conditions and reformed products, exploration of bio-oil and its model substances hydrogen production reaction law and reaction mechanism, catalyst preparation, deactivation and regeneration research. Many scholars at home and abroad have studied the law of hydrogen production by bio-oil reforming and the basic conditions of reforming. The reforming temperature is relatively high, generally between 700 _and 800 ° C. Excessively high temperatures will lead to a large amount of carbon deposits. In order to further improve the catalytic effect, Inhibiting the generation of coke and researching catalysts for hydrogen production by catalytic reforming of bio-oil are of great significance for increasing hydrogen yield and inhibiting coking. How to overcome the defects of existing technologies and reduce energy consumption and production costs is still a difficult problem in the hydrogen production process of biomass and bio-oil.

Attapulgite is a layered and chain-like hydrous-rich magnesium-aluminosilicate material with a special fibrous crystal structure, rich internal pores, and a large specific surface area (125-210m ² /g), which has excellent adsorption, storage and auxiliary properties. Catalytic function. Sepiolite not only has a high specific surface area, but also has molecular sieve-like characteristics, especially its microscopic skeleton is a "cage" structure composed of nanoscale hollow fibers. The particularity of its structure determines that it has a cross-sectional area of 0.36mx 1.06nm Tubular through-channels and a theoretical surface area of up to 900 m ² /g. At the same time, its three-dimensional bond structure Si-O-Si bond pulls the fine chain together, making it have a special crystal shape that is always extended. The open groove pivot formed in the structure is parallel to the long axis of the crystal, so the groove pivot Strong adsorption capacity. The inner and outer surfaces of sepiolite are divided into three kinds of adsorption centers: ① The main adsorption center is the water molecule coordinated with the magnesium ion on the edge of the structure, and the adsorbed water forms hydrogen bonds with it; ② Si-OH ion group, which accepts a The proton or hydrocarbon group compensates the remaining electricity price, and this ion group often forms a covalent bond with the adsorbed substance; ③ the oxygen atom in the silicon-oxygen tetrahedral sheet is a weak electron donor in the process of isomorphic replacement. China is rich in attapulgite, sepiolite and rare earth resources. Since attapulgite and sepiolite have different micropore diameters, their combined use can further improve their adsorption selectivity for different gas components.

At present, rapid biomass pyrolysis technology can obtain a high yield of liquid products, but the bio-oil produced has complex components, direct reforming of hydrogen is easy to coke, and the yield of hydrogen is not high. In order to suppress coking, the current research on hydrogen production from biomass is carried out in two steps, that is, the first step is to quickly crack the biomass, cool the bio-oil vapor to obtain crude oil, and separate the crude oil to obtain water phase and oil phase. The oil phase part can be used to make chemical raw materials, and the water phase part can be used to reform hydrogen production. The development of low-cost, high-efficiency, and easy-to-regenerate reforming hydrogen production catalysts will be of great significance.

Contents of the invention

The present invention aims to solve the deficiencies in the existing bio-oil reforming hydrogen production technology, and provides a method for expanding the contact between the bio-oil component and the composite metal and increasing the water vapor on the catalyst surface during the bio-oil reforming process. Adsorption speeds up the gasification rate of carbon or carbon precursors on the surface and improves the catalytic performance of the catalyst. The invention also provides a preparation method for the catalyst.

The present invention solves technical problem and adopts following scheme:

A catalyst for catalytic hydrogen production from bio-oil, comprising a catalyst active component and a catalyst carrier, characterized in that the catalyst active component and its weight percentage are respectively: Ni is 10-15wt%; Mo is 5-13wt% ; Fe is 5-10wt%; the rest is divided into attapulgite and sepiolite mixed clay ore catalyst carrier, and the mass ratio of attapulgite and sepiolite mixed clay ore is 1:1.

Preferably, in the catalyst of the present invention, Ni is 15wt%; Mo is 12wt%; Fe is 15wt%.

A method for preparing a catalyst for catalytic hydrogen production from bio-oil, characterized in that, the steps are as follows:

(1) Take sepiolite and attapulgite raw clay mineral powder with a mass ratio of 1:1, then add distilled water according to the mass (g)/volume ratio (ml) 100:50-70, stir for 10 minutes; statically pour out the upper suspension, Take the suspension in the middle layer; vacuum filter the suspension in the middle layer, and obtain a solid filter cake after filtration, and dry and grind the solid filter cake at 105°C; obtain a mixed powder of sepiolite and attapulgite raw clay;

(2) Dissolve the soluble salts of nickel, molybdenum and iron in water together, the total concentration of soluble salts is 0.05-1.5mol/l, then add the mixed powder of attapulgite and sepiolite while heating, stir and impregnate at a constant temperature of 60°C 6h into emulsion;

(3) To the emulsion in step (2), add magnesium nitrate, cetyltrimethylammonium bromide, and magnesium nitrate as a reinforcing agent to enhance cohesiveness. The content of magnesium nitrate accounts for 5% of the total emulsion weight. -10wt%, cetyltrimethylammonium bromide is used as a surfactant template compound to increase the dispersion of the active surface and active components, the content accounts for 0.1-1.0wt% of the total emulsion weight, and then add alkaline Precipitating agent, adjust the pH value to 8-12, after precipitation, washing, filtration, drying, molding and roasting, the catalyst Ni-Mo-Fe-clay ore can be obtained;

The amount of the nickel salt is 10-20wt% of the catalyst Ni-Mo-Fe-clay ore based on the weight of nickel in the catalyst, and the amount of the molybdenum salt is the catalyst Ni-Mo-Fe-clay ore based on the weight of molybdenum in the catalyst. 5-20wt% of the catalyst Ni-Mo-Fe-clay ore, the amount of the iron salt is 5-15wt% based on the weight of iron in the catalyst.

The nickel, molybdenum and iron soluble salts are respectively selected from the following compounds: nickel nitrate, ammonium molybdate, iron nitrate, and the alkaline precipitant is selected from ammonia water.

The mixed powder of sepiolite and attapulgite raw clay obtained in the step (1) is soaked in a nitric acid solution with a concentration of 1.0-2.0 mol/L at 20°C for 24- After 48 hours, wash repeatedly with deionized water, heat and dry the filter cake at 120°C for 4 hours, and then grind it after natural cooling; then calcinate the ground powder at 900°C for 4-6 hours, and then crush it to below 120 mesh.

The calcination time is 2-6 hours, and the calcination temperature is 600°C-900°C.

Compared with the prior art, the beneficial effects of the present invention are reflected in:

The invention provides a catalyst for converting bio-oil into high-quality combustible gas in the hydrogen production process of catalytic reforming of bio-oil. Compared with the current catalytic reforming technology, it is expected to obtain high-quality combustible gas with high hydrogen content and high calorific value. Improve the economic and technical performance of biomass conversion to clean energy. The raw ore powder of sepiolite and attapulgite used in the catalyst carrier is cheap and easy to obtain, reducing the production cost. Magnesium nitrate is added to the catalyst to enhance the binding force, cetyltrimethylammonium bromide increases the active surface and the dispersion of active components, and molybdenum, nickel, and iron metals are used as catalyst active components, which effectively improves the catalytic performance.

The technical solutions of the present invention will be further described below through examples.

Detailed ways:

1. Raw material preparation

Take 50g of sepiolite (commercially available) and attapulgite raw ore powder (commercially available) with a mass ratio of 1:1, add 120ml of distilled water, and stir for 10min; statically pour out the upper suspension, and take the middle suspension. The suspension in the middle layer was vacuum filtered, and the solid filter cake was dried and ground at 105°C. Acid activation: activate with nitric acid (concentration 1.0-2.0 mol/L), solid-liquid ratio (g/ml) 1:10, soak for 24-48h at 20°C, wash repeatedly with deionized water, filter the filter cake at 120°C Heat and dry at high temperature for 4 hours, and then grind it after natural cooling.

Calcinate the ground powder at 900°C for 4-6 hours, then crush it to below 120 mesh, dissolve a certain amount of soluble salts of nickel, molybdenum and iron in deionized water respectively, the total concentration of soluble salts is 0.05-1.5mol /l; then add sepiolite and attapulgite mixed clay ore powder while heating, stir and impregnate at 60°C for 6 hours to form an emulsion.

2. Co-precipitation

With the emulsion obtained above, add magnesium nitrate, cetyltrimethylammonium bromide, and magnesium nitrate as a reinforcing agent to enhance cohesiveness. The content of magnesium nitrate accounts for 5-10wt% of the total emulsion weight , cetyltrimethylammonium bromide is used as a surfactant template compound to increase the dispersion of the active surface and active components, and the content accounts for 0.1-1.0wt% of the total emulsion weight; the amount of nickel salt in the soluble salt is The weight of nickel is 10-20wt% of catalyst Ni-Mo-Fe-clay ore, the amount of molybdenum salt is 5-15wt% of catalyst Ni-Mo-Fe-clay ore by weight of molybdenum, and the amount of iron salt is 5-15wt% of catalyst Ni-Mo-Fe-clay ore. The weight is 5-15wt% of the catalyst Ni-Mo-Fe-clay ore. Then add alkaline precipitating agent ammonia water to the above solution, keep the pH value of the solution at 8-12, precipitate out, let stand for 6 hours, precipitate and age.

3. Molding and calcination

The filter cake obtained after suction filtration is washed with water and dried, and the filter cake is pressed to 200MP with a catalyst former. After the catalyst is formed, the particle size is about 2-4mm, and then roasted for 4 to 6 hours at a roasting temperature of 600°C to 900°C. The weight percentages of each catalytic active component and carrier are respectively: 10-20wt% for Ni; 5-15wt% for Mo; 5-15wt% for Fe; the rest are sepiolite and attapulgite mixed clay catalyst carrier.

Example 1

Using glycerol as the raw material of the bio-oil model, it was carried out in a fixed-bed reactor for reforming experiments, and the catalyst of the present invention was used to carry out catalytic reforming of glycerin steam, the feed rate was 1.8g/min, and the catalytic reforming The time was 30 minutes and the gaseous product was collected. The gas product obtained without catalyst action contains 31.47% of H ₂ , 22.52% of CO 2 , 10.32% of CH ₄ , 35.69% of CO ₂ , and the conversion rate of bio-oil is 89%.

The gas product obtained under the action of the catalyst of the present invention contains 61.47% of H ₂ , 7.52% of CO 2 , 3.34% of CH ₄ , 17.67% of CO ₂ , and a bio-oil conversion rate of 95%.

Example 2

Taking acetic acid as the bio-oil model raw material, it is carried out reforming experiment in fixed-bed reactor, and adopts the catalyst prepared by the method of the present invention to carry out catalytic reforming to acetic acid steam, feed rate is 1.8g/min, catalytic reforming time For 30 minutes, the gaseous product was collected. The gas product obtained without catalyst action contains 36.47% of H ₂ , 3.52% of CO 2 , 6.33% of CH ₄ , 33.68% of CO ₂ , and the conversion rate of bio-oil is 87%.

The gas product obtained under the action of the inventive catalyst contains 65.23% of H ₂ , 3.12% of CO ₂ , 1.24% of CH ₄ , 10.41% of CO ₂ , and the conversion rate of bio-oil is 97%.

Example 3

Using the bio-oil water phase component rapidly cracked by biomass wheat straw as raw material, carry out reforming experiments in a fixed-bed reactor, and use the catalyst prepared by the method of the present invention to carry out catalytic reforming of the bio-oil water phase component steam, feed The rate was 2.2 g/min, the catalytic reforming time was 30 minutes, and the gaseous product was collected. The gas product obtained without catalyst action contains 21.47% of H ₂ , 25.43% of CO, 14.32% of CH ₄ , 38.78% of CO ₂ , and the conversion rate of bio-oil is 85%.

The gas product obtained under the action of the inventive catalyst contains 67.5% of H ₂ , 13.5% of CO, 1.38% of CH _{4 ,} 17.62% of CO ₂ , and the conversion rate of bio-oil is 95%.

Claims (5)

1. A catalyst for catalytic hydrogen production from bio-oil, comprising a catalyst active component and a catalyst carrier, characterized in that the catalyst active component and weight percentage are respectively: Ni is 10-15wt%; Mo is 5- 13wt%; Fe is 5-10wt%; the rest is divided into attapulgite and sepiolite mixed clay ore catalyst carrier, and the mass ratio of attapulgite and sepiolite mixed clay ore is 1:1. 2. A catalyst preparation method for bio-oil catalytic hydrogen production, characterized in that, proceed as follows: (1) Take sepiolite and attapulgite raw clay mineral powder at a mass ratio of 1:1, then add distilled water according to mass/volume ratio = 100g: 50-70ml, stir for 10min; let stand, pour out the upper suspension, and take the middle layer Suspension; vacuum filter the suspension in the middle layer, and obtain a solid filter cake after filtration, and dry and grind the solid filter cake at 105°C; obtain a mixed powder of sepiolite and attapulgite raw clay; (2) Dissolve the soluble salts of nickel, molybdenum and iron in water together, the total concentration of soluble salts is 0.05-1.5mol/l, then add the mixed powder of attapulgite and sepiolite while heating, stir and impregnate at a constant temperature of 60°C 6h into emulsion; (3) to the emulsion of step (2), add magnesium nitrate, cetyltrimethylammonium bromide simultaneously, magnesium nitrate is as reinforcing agent, strengthens cohesiveness, and the content of magnesium nitrate accounts for 5% of total emulsion weight -10wt%, cetyltrimethylammonium bromide is used as a surfactant template compound to increase the dispersion of the active surface and active components, and the content accounts for 0.1-1.0wt% of the total emulsion weight, and then add alkaline Precipitating agent, adjust the pH value to 8-12, after precipitation, washing, filtration, drying, molding and roasting, the catalyst Ni-Mo-Fe-clay ore can be obtained; The amount of the nickel salt is 10-20 wt% of the catalyst Ni-Mo-Fe-clay ore based on the weight of nickel in the catalyst, and the amount of the molybdenum salt is the catalyst Ni-Mo-Fe-clay ore based on the weight of molybdenum in the catalyst. 5-20 wt% of the catalyst Ni-Mo-Fe-clay ore. 3. a kind of catalyst preparation method that is used for bio-oil catalytic hydrogen production according to claim 2 is characterized in that, described nickel, molybdenum and iron soluble salt are selected from following compound respectively: nickel nitrate, ammonium molybdate, Ferric nitrate, the alkaline precipitation agent is selected from ammonia water. 4. a kind of catalyst preparation method that is used for bio-oil catalytic hydrogen production according to claim 2 is characterized in that, the sepiolite and attapulgite former clay mixed powder of gained in the described step (1) are with solid-to-liquid ratio= 1g: 10ml, soak in nitric acid solution with a concentration of 1.0-2.0mol/L for 24-48h at 20°C, wash repeatedly with deionized water, heat and dry the filter cake at 120°C for 4h, cool naturally and then grind it; The ground powder was calcined at 900°C for 4-6 hours, and then crushed to below 120 mesh. 5. A method for preparing a catalyst for catalytic hydrogen production from bio-oil according to claim 2, characterized in that, the roasting time in the step (3) roasting step is 2 to 6 hours, and the roasting temperature is 600 ° C to 6 hours. 900°C.