CN111068688A

CN111068688A - Method for catalyzing methane cracking by using iron waste as catalyst

Info

Publication number: CN111068688A
Application number: CN201911316590.8A
Authority: CN
Inventors: 钱敬侠; 陈天文; 周吕; 李丽萍
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2019-12-19
Filing date: 2019-12-19
Publication date: 2020-04-28

Abstract

The invention discloses a method for catalyzing methane cracking by using iron waste as a catalyst, belonging to the technical field of catalysis. The method takes industrial waste iron fine ash, coarse ash, steel slag, volcanic mud powder and hematite powder as catalysts to catalyze methane to crack so as to prepare the hydrogen and carbon materials, fully utilizes mineral components with catalysis and catalysis assisting functions in the iron waste, takes methane as a raw material, and reacts at the temperature of 700-1200 ℃ under normal pressure. On one hand, the method fully utilizes the catalytic activity of metal and oxide thereof in the iron waste, is applied to the hydrogen production reaction by catalytic methane cracking, and reduces the cost of the catalyst, thereby greatly reducing the cost of the hydrogen production by catalytic methane; on the other hand, the resource utilization of the iron waste is fully realized, and a new direction is opened for the resource comprehensive utilization of the iron waste.

Description

Method for catalyzing methane cracking by using iron waste as catalyst

Technical Field

The invention relates to a method for preparing hydrogen and carbon material by catalyzing methane cracking by using iron waste as a catalyst.

Background

Hydrogen, the simplest and lightest component, is known to be present in large quantities in the earth's world and has been considered a clean energy source. However, hydrogen is not the primary fuel, on earthThere is no natural source of hydrogen. Thus, hydrogen must be extracted from raw energy resources such as carbon, natural gas, naphtha, heavy oil, biomass, waste materials, solar energy, wind energy, or nuclear energy, which are present in large quantities, at low cost, and is required to be free from environmental pollution. Global data indicate that 48% (240 parts per billion cubic meters) of hydrogen is produced from natural gas, 30% (150 parts per billion cubic meters) is produced from oil, 18% is produced from carbon, however only 4% is produced by water electrolysis. In recent years, various methods of hydrogen production such as steam reforming of methane, cracking of methane, partial oxidation of methane, gasification of carbon, dissociation of water, gasification of biomass, and thermochemical processes have been developed. Wherein the cracking of methane produces CO-free_XThe hydrogen and carbon material technology of (a) is attracted as a novel eco-friendly hydrogen production technology.

In the last decades, efforts have been made to achieve methane cracking under mild conditions in order to develop simple and efficient synthesis methods to prepare suitable catalysts. It has been found that the catalytic activity of the metal catalyst for methane cracking reaction is in the following order: ni, Ru, Rh > Pt, Re, Ir > Pd, wherein, the Ni-based catalyst which is relatively low in price and high in activity still has the defect of easy inactivation at high temperature (>750 ℃), and the methane conversion rate cannot be further improved under the limitation of the equilibrium conversion rate.

Therefore, although some of the noble metals, transition metals and composite catalysts thereof mentioned above have good activity in the methane cracking process, the methane cracking hydrogen production technology is still in the laboratory research stage due to the characteristics of expensive price, complex preparation process and easy deactivation of the catalysts. Therefore, how to develop a low-cost and high-efficiency catalyst becomes a great challenge of methane cracking hydrogen production technology.

Disclosure of Invention

The invention aims to provide a method for preparing hydrogen and carbon material by catalyzing methane cracking by using iron waste as a catalyst. On one hand, the resource utilization of the iron waste is realized, and the environmental pollution is reduced; on the other hand, the cost of the methane cracking catalyst is reduced, and the industrial application of the methane cracking process is facilitated. The technical scheme of the invention is as follows:

(1) crushing and grinding the iron waste to 10-200 um;

(2) taking 1.0-3.0 g of iron waste, taking quartz wool as a filling material, and filling the quartz wool into a gas-solid phase catalytic fixed bed reactor;

(3) and (3) introducing 20-200 mL/min methane gas into the gas-solid phase reactor, heating to 700-1200 ℃, and reacting under the normal pressure condition to obtain the product hydrogen and the carbon material.

Preferably, the iron waste includes fine ash, coarse ash, steel slag, pozzolan powder and hematite powder.

Preferably, the catalyst is filled into a gas-solid phase catalytic fixed bed reactor with the length of 40cm and the inner diameter of 2.1 cm.

Preferably, in the step (3), the heating rate is 10 ℃/min.

Preferably, the temperature is increased to 800-1000 ℃, and the reaction is carried out under the condition of normal pressure.

Compared with the prior art, the invention has the beneficial effects that:

1. the iron waste catalyst adopted by the invention is used for the hydrogen production by methane cracking and the carbon material reaction, so that the complex process of catalyst preparation is avoided, the cost of the catalyst is reduced, and the iron waste catalyst has important application value for improving the economic benefit of the hydrogen production by methane cracking.

2. The invention makes full use of Fe in iron waste₂O₃，Fe₃O₄，Al₂O₃，SiO₂，MgO，TiO₂And the metal oxide which is beneficial to catalysis enables the methane cracking hydrogen production reaction to be carried out under a milder condition.

3. The invention reduces the pollution of the iron waste to the environment and realizes the resource recycling of the waste.

Drawings

FIG. 1 is a graph showing the conversion of methane obtained by cracking methane using five catalysts.

FIG. 2 is a diagram of a byproduct solid carbon material from methane cracking.

Detailed Description

The solution according to the invention is explained in detail below with reference to the figures and examples.

The reaction for preparing hydrogen by cracking methane by using the iron waste as the catalyst is suitable for any reactor which takes solid as the catalyst and gas as the reaction raw material. The reactor in the technical scheme is preferably a fixed bed reactor. The catalyst activities in the following examples are, in order, fine ash > coarse ash > steel slag > hematite powder > volcanic mud powder.

Examples

(1) The iron wastes of fine ash, coarse ash, steel slag, volcanic mud powder and red iron powder are respectively crushed and ground to 10-200 um for later use, and the specific surface area, the pore volume and the pore size are shown in table 1.

TABLE 1

(2) The fine ash, the coarse ash, the steel slag, the volcanic mud powder and the red iron powder are respectively taken as catalysts, quartz wool is taken as a filling material, and the catalysts are filled into a gas-solid phase catalytic fixed bed reactor with the length of 40cm and the inner diameter of 2.1 cm.

(3) 50mL/min of methane gas is introduced into the gas-solid phase reactor, the temperature is raised to 1000 ℃ at the heating rate of 10 ℃/min, and the reaction is carried out under the condition of normal pressure, so as to prepare the product hydrogen and the carbon material, wherein the morphology of the carbon material is shown in figure 2.

(4) The change curve of the methane conversion rate of the hydrogen production by methane catalytic cracking with time is shown in figure 1

(5) The formula for the methane conversion is:

in the formula:

-the volume fraction of hydrogen in the outlet gas component;

-the volume fraction of methane in the outlet gas component;

conversion of methane.

Under the condition that the reaction temperature, the methane flow rate and other experimental conditions of the five catalysts are the same, the activity and stability of the catalysts are analyzed and found to be in the following order within 300min of reaction time: fine ash, coarse ash, steel slag, hematite powder and volcanic mud powder. The analysis of the five catalysts by a BET test shows that the activity of the catalyst is not in a positive correlation with the specific surface area of BET.

Although the invention has been described in detail above with reference to a general description and specific embodiments, it will be apparent to those skilled in the art that modifications or improvements may be made based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims

1. A method for catalyzing methane cracking by taking iron waste as a catalyst is characterized by comprising the following steps:

(1) crushing and grinding the iron waste to 10-200 um;

2. The method of claim 1, wherein the iron waste comprises fine ash, coarse ash, steel slag, pozzolan, and hematite powder.

3. The method as claimed in claim 1, wherein 1.0-3.0 g of iron waste is taken and quartz wool is used as a filling material, and the iron waste is filled into a gas-solid phase catalytic fixed bed reactor with the length of 40cm and the inner diameter of 2.1 cm.

4. The method according to claim 1, wherein in the step (3), the temperature increase rate is 10 ℃/min.

5. The method of claim 1, wherein the temperature is raised to 800 to 1000 ℃ and the reaction is carried out under normal pressure.