阅读说明：本技术 半焦负载型焦油水蒸气重整催化剂及其制备方法和应用 (Semicoke-loaded coke oil steam reforming catalyst and preparation method and application thereof ) 是由 白永辉 王焦飞 宋旭东 苏暐光 马萌 于广锁 于 2019-10-08 设计创作，主要内容包括：本发明公开了一种半焦负载型焦油水蒸气重整催化剂及其制备方法和应用,半焦负载型焦油水蒸气重整催化剂,以氧化剂预处理的低阶煤为催化剂载体前驱体,Ni为金属活性组分。发明以廉价的低阶煤为催化剂载体前驱体,丰富了催化剂的表面酸性位点,并且加强了载体-金属的相互作用,提高了原子利用效率,进一步提升了催化剂活性。极大降低了生产成本,可用于催化生物质或低阶煤气化焦油水蒸气重整,具有较高的碳转化率。(The invention discloses a semicoke-loaded coke tar steam reforming catalyst and a preparation method and application thereof. The invention takes low-cost low-rank coal as a catalyst carrier precursor, enriches the surface acid sites of the catalyst, strengthens the interaction of the carrier and metal, improves the atom utilization efficiency and further improves the activity of the catalyst. Greatly reduces the production cost, can be used for catalyzing the reforming of biomass or low-rank coal gasification tar steam, and has higher carbon conversion rate.)

1. The semicoke-loaded coke oil-steam reforming catalyst is characterized in that low-rank coal pretreated by an oxidant is used as a catalyst carrier precursor, and Ni is used as a metal active component.

2. The semicoke-supported coke steam reforming catalyst according to claim 1, wherein the mass percentage of Ni is 7 to 13%.

3. The semicoke-supported coke steam reforming catalyst according to claim 2, wherein the mass percentage of Ni is 7.2 to 12.1%.

4. The preparation method of the semicoke-based supported tar steam reforming catalyst is characterized by comprising the following steps of:

(1) mixing and stirring an oxidant aqueous solution and target coal, and then collecting low-rank coal oxidized by an oxidant from a system;

(2) mixing and stirring the product obtained in the step (1) and a nickel salt aqueous solution with the pH value of 10-12, and then collecting a catalyst precursor from a system;

(3) and (3) pyrolyzing the catalyst precursor in the step (2) in an inert atmosphere to obtain the semicoke-loaded coke-oven water vapor reforming catalyst.

5. The method according to claim 4, characterized in that in the step (1), the mixture is stirred for 2-6 hours at 30-50 ℃, and then the low-rank coal oxidized by the oxidant is collected from the system, wherein the ratio of the target coal to the oxidant is 5-10 mL/g; the oxidant is selected from nitric acid or hydrogen peroxide.

6. The method according to claim 4, wherein in the step (2), the product obtained in the step (1) is mixed with a nickel salt aqueous solution with the pH value of 10-12, the mixture is stirred for 16-32 hours at the temperature of 25-35 ℃, and then a catalyst precursor is collected from the system;

the pH value of the nickel salt aqueous solution is adjusted by ammonia water;

the mixing ratio of the nickel salt solution to the low-rank coal oxide is 5-15 mL/g.

7. The method of claim 6, wherein the nickel salt is selected from one or more of nickel acetate tetrahydrate, nickel nitrate hexahydrate, nickel sulfate hexahydrate, and anhydrous nickel chloride.

8. The method according to claim 6, wherein the concentration of the nickel salt aqueous solution is 0.1 to 0.3 mol/L.

9. The method of claim 4, wherein in step (3), said pyrolyzing comprises the steps of: heating from room temperature to 550-700 ℃, wherein the heating rate is 5-10 ℃/min, and the retention time is 1-3 hours.

10. The application of the semicoke-supported tar steam reforming catalyst according to any one of claims 1 to 3, wherein the catalyst is used for catalyzing biomass or low-rank coal gasification tar steam reforming.

Technical Field

The invention belongs to the technical field of energy chemical industry, and particularly relates to a semicoke-loaded coke oil steam reforming catalyst and a preparation and application method thereof.

Background

Gasification is one of the main technologies for clean and efficient conversion of coal, is widely applied to the fields of chemical synthesis, industrial gas, metallurgical reducing gas production, coal-based poly-generation and the like, and is the core and key of the technology.

The tar is an inevitable byproduct of low-temperature gasification of low-rank coal, and the content of the tar in the discharged gasification gas is 5-75 g/Nm³The tar is not uniformly pyrolyzed and can block pipelines and corrode downstream equipment, so that the catalyst in the subsequent process is inactivated, and a plurality of obstacles are caused to the clean utilization of low-rank coal.

In various tar removal technologies, catalytic reforming not only has high tar removal efficiency and relatively mild operating conditions, but also can fully utilize a large amount of water vapor and CO in the raw synthesis gas₂Reforming tar to H₂And CO, and the like, and catalytic reforming of tar is considered to be the most promising tar removal method for large-scale application.

Different types of catalysts are used for the removal of tar from gasification gas, such as high temperature roasted rock, molecular sieves, iron ore, Alkali and Alkaline Earth Metals (AAEMs), nickel based catalysts, and noble metal catalysts, wherein nickel based catalysts possess optimal catalytic activity. The nickel-based catalyst is generally supported on a metal oxide support, a molecular sieve support, a natural ore support, and a coke support. Compared with other carriers, the coal coke or biomass coke serving as a pyrolysis byproduct is cheap and easy to obtain, contains abundant alkali metals and alkaline earth metals, has high specific surface area and oxygen-containing functional groups, and has certain tar removal activity.

Wang et al (Applied Energy,2011,88(5): 1656-.

CN 107715884A discloses a metal-loaded biomass semi-coke catalyst and a preparation method thereof, wherein a metal active component is loaded on a biomass precursor subjected to acid washing pretreatment through isovolumetric impregnation, the metal active component comprises a second active metal formed by active metal Ni and one of Fe, Co or Cu, and the tar reforming catalyst is prepared through sequential temperature rise. The method adopts equal-volume impregnation to load the active component, the active component is difficult to be uniformly dispersed in a pore structure of the carrier, the interaction force between the carrier and the metal is weak, and the utilization rate of the metal active component is low in the catalytic process.

CN 103846088A discloses a preparation and application method of a nickel-based biomass tar steam reforming catalyst, the catalyst takes lignite pretreated by sodium hydroxide as a carrier precursor, the lignite is subjected to ion operation and then is subjected to standing filtration, and the volatile components of the lignite are removed through temperature programming, so that the nickel-based biomass tar steam reforming catalyst is obtained. After lignite is treated by sodium hydroxide, acid sites (oxygen-containing functional groups) on the surface of a carrier are damaged, and the interaction of metal and the carrier is greatly weakened; secondly, after ion exchange, without a water washing step, the excessive nickel salt adheres to the surface of the carrier, so that the catalyst has a low specific surface area and a less porous structure.

Disclosure of Invention

The invention aims to disclose a semicoke-supported coke oil steam reforming catalyst, a preparation method and application thereof, so as to overcome the defects in the prior art and meet the application requirements of the related fields.

The semicoke-based supported tar steam reforming catalyst takes low-rank coal pretreated by an oxidant as a catalyst carrier precursor and Ni as a metal active component. Wherein the mass percent of Ni is 7-13%, preferably 7.2-12.1%;

the preparation method of the semicoke-based supported tar steam reforming catalyst comprises the following steps:

(1) mixing an oxidant aqueous solution with target coal, stirring for 2-6 h, preferably 4h at 30-50 ℃, preferably 40 ℃, and then collecting low-rank coal oxidized by an oxidant from a system;

the ratio of the target coal to the oxidant is 5-10 mL/g, preferably 5 mL/g;

the oxidant is selected from nitric acid or hydrogen peroxide, and the mass concentration of the oxidant aqueous solution is 10-30%;

the target coal is low-rank coal particles with the particle size of 80-160 meshes, and the industrial analysis and the elemental analysis of the target coal sample are shown in table 1;

TABLE 1 Industrial and elemental analysis of target coal samples

The method for collecting the oxidized low-rank coal comprises the steps of filtering, washing with water to be neutral, and drying at the temperature of 60-80 ℃ until the moisture content is lower than 5% by mass;

(2) mixing the product obtained in the step (1) with a nickel salt aqueous solution with the pH value of 10-12, stirring at 25-35 ℃ for 16-32 hours, preferably 24 hours, and then collecting a catalyst precursor from the system;

the collection method comprises the following steps:

filtering the obtained mixture, collecting filter residues, washing the filter residues with water to be neutral, and drying the filter residues at the temperature of 60-80 ℃, preferably 70 ℃ until the water content is lower than 5% by mass;

the concentration of the nickel salt aqueous solution is 0.1-0.3 mol/L, preferably 0.2 mol/L;

the nickel salt is selected from more than one of nickel acetate tetrahydrate, nickel nitrate hexahydrate, nickel sulfate hexahydrate or anhydrous nickel chloride, and preferably nickel acetate tetrahydrate;

the preparation method of the nickel salt aqueous solution is conventional, wherein the pH can be adjusted by alkaline substances, such as ammonia water, sodium hydroxide solution or potassium hydroxide solution, and ammonia water is preferred;

the mixing ratio of the nickel salt solution to the low-rank coal oxide is 5-15 mL/g, and preferably 10 mL/g.

(3) Pyrolyzing the catalyst precursor in the step (2) in an inert atmosphere to stabilize the crystal form of elemental nickel on the surface of the catalyst, removing volatile components in a carrier, increasing the specific surface area of the catalyst, and pyrolyzing to obtain the semicoke-loaded coke oil-steam reforming catalyst;

the pyrolysis comprises the following steps:

heating the mixture from room temperature to 550-700 ℃, preferably 600 ℃;

the heating rate is 5-10 ℃/min, preferably 10 ℃/min;

the retention time is 1-3 hours, preferably 2 hours;

the semicoke-loaded coke tar steam reforming catalyst can be used for catalyzing the steam reforming of biomass or low-rank coal gasification coke tar.

According to the invention, cheap low-rank coal is used as a catalyst carrier precursor, and in the active component loading process, the characteristic that the low-rank coal contains rich oxygen-containing functional groups is fully considered, so that the low-rank coal is subjected to oxidation treatment in different degrees, the number of the oxygen-containing functional groups in the coal is adjusted, and the nickel loading capacity is improved while good dispersion degree and crystallite size are maintained. In addition, the number of oxygen-containing functional groups on the surface of the carrier is increased through oxidation treatment, so that the surface acid sites of the catalyst are enriched, the interaction of the carrier and metal is enhanced, the atom utilization efficiency is improved, and the activity of the catalyst is further improved.

The invention has the beneficial effects that:

the raw material of the carrier of the catalyst is low-rank coal, the number of oxygen-containing functional groups on the surface of the coal is increased by oxidation pretreatment, and the low-rank coal is Ni²⁺The effective load on the coal sample provides more exchange sites, so that the catalyst maintains good Ni dispersion degree and smaller crystallite size in the process of increasing the Ni load;

the invention enhances the carrier-metal interaction of the catalyst while improving the loading capacity of the catalyst, the catalyst is easy to form more defect structures with negative electrons in the catalytic tar steam reforming process, the combination probability of the catalyst and activated tar fragments is increased, and the atomic utilization efficiency of the catalyst is further improved;

in the ion exchange process, ammonia water is used to regulate the pH of metal salt solution, so that nickel salt is mainly Ni (NH)₄)₆ ²⁺On the other hand, the O-H bond in the oxygen-containing functional group on the surface of the coal is easier to break, and Ni (NH) is promoted₄)₆ ²⁺Bonding with oxygen-containing functional groups on the surface of the coal;

the carrier of the catalyst is low-rank coal, the specific surface area of the catalyst is increased through oxidation pretreatment, and redundant nickel salt is washed away through a water washing step after the ion exchange step is finished, so that the dispersion degree of Ni is improved;

the semicoke loaded coke oil steam reforming catalyst carrier selects low-rank coal, and the loaded nickel salt is reduced in situ in the coal sample pyrolysis devolatilization process to obtain a reduced Ni component, so that the hydrogen reduction step is omitted, and the semicoke loaded coke oil steam reforming catalyst carrier is simple and convenient to use;

coal is used as one ore resource, contains abundant alkali metal and alkaline earth metal, and can be used as a catalyst auxiliary agent to play a catalytic role in the tar steam reforming process, so that the catalytic performance of the catalyst is improved to a certain extent, and compared with other types of tar reforming catalysts, the coal tar reforming catalyst omits an auxiliary agent adding step, so that the production cost is greatly reduced;

drawings

FIG. 1 is a TEM image of a semicoke-supported coke steam reforming catalyst prepared in example 3 of the present invention;

FIG. 2 is a TEM image of a semicoke-supported coke steam reforming catalyst prepared in example 5 of the present invention;

FIG. 3 is an XRD pattern of a semicoke-supported coke vapor reforming catalyst prepared according to various embodiments of the present invention;

Detailed Description

The semicoke-supported coke oil steam reforming catalyst can be evaluated by the following method:

the catalyst is placed in a fixed bed reactor, nitrogen is used as carrier gas, toluene and water vapor are vaporized by a preheating furnace and then are sent into the reactor, and the space velocity of reactants in the reactor is 7200h^-1The reaction temperature is 600 ℃, and CO and H are obtained₂And (4) waiting for small molecule gas products.

Collecting the product gas, detecting the gas composition by Raman gas analyzer (RLGA) to obtain n_CO、

By controlling the flow rate of toluene entering the reactor and the reaction time, the method is obtained

The carbon conversion was then calculated and the toluene carbon conversion was defined as formula (1):

wherein:

n_COrepresents the amount of CO species in the product;

representing CO in the product₂The amount of the substance;

represents CH in the product₄The amount of the substance;

represents the amount of carbon in the reactant toluene;