CN1117941A

CN1117941A - Ceramic-metal composite film reactor and its preparation and application

Info

Publication number: CN1117941A
Application number: CN 94112487
Authority: CN
Inventors: 吴迪镛; 付桂芝; 洪学伦; 孙立新; 袁权
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 1994-09-02
Filing date: 1994-09-02
Publication date: 1996-03-06
Anticipated expiration: 2014-09-02
Also published as: CN1046251C

Abstract

The present invention relates to a ceramic-metal composite film reactor hydrogen-producing method for methanol steam conversion hydrogen production. It is characterized by that the thickness of metal film of said reactor is 1-10 micrometers, its adoped reaction temp. is 250-300 deg.C, and a pressure operation mode is used to prepare pure hydrogen. Its hydrogen purity is up to 100%, methanol conversion efficiency is 80%, H2 recovery rate is 90%, and its film permeability is up to 60-150 ml/square cm.min. square root of atm.

Description

Ceramic-metal composite membrane reactor and preparation and application thereof

The invention belongs to the field of chemical industry, and particularly relates to a preparation of an inorganic membrane reactor and a hydrogen extraction process.

The reaction of preparing hydrogen by converting methanol steam into hydrogen-rich gas containing hydrogen, carbon monoxide, carbon dioxide and unreacted methanol and water, and separating out crude hydrogen and pure hydrogen, which is a common hydrogen preparing method in industry.

Japanese patent (sho 63-295402) proposes a method for producing hydrogen using a porous glass-Pd-Cu composite membrane reactor, which employs a membrane reactor to synchronize reaction-separation, breaks the chemical equilibrium limitation, and improves the conversion rate, but this method employs a high operating temperature to achieve a high hydrogen yield and prevent hydrogen embrittlement, and is high in energy consumption, and the process has a low gas production rate, and the direct product is a mixed gas of hydrogen and hydrogen, not pure hydrogen, and is difficult to separate.

The invention aims to overcome the defects and provide a metal composite membrane reactor capable of preparing pure hydrogen and a method for preparing hydrogen by using the reactor.

The invention uses the inner wall of a ceramic-ultrathin metal palladium (or palladium-silver alloy) membrane tube to form a permeation cavity, uses a concentric annular space between a stainless steel tube and the outer wall of the palladium membrane tube to form a reaction cavity, and fills a methanol decomposition hydrogen production catalyst in the reaction cavity to form an operable membrane reactor for producing pure hydrogen. The thickness of a palladium-silver metal film plated on a ceramic base pipe of the membrane reactor is 1-10 mu m, the metal film is Pd-Ag alloy, and the contents of the Pd-Ag (palladium-silver) alloy are respectively palladium (Pd): 70-100%, silver: 0 to 30 percent.

The preparation method of the composite membrane is to carry out surface treatment on a commercial ceramic base tube and then obtain the composite membrane by a method of chemically plating Pd or chemically plating Pd-Ag. Specifically, the ceramic base tube is subjected to surface treatment to form a ceramic matrix with the average pore diameter of 0.02-3 microns, preferably 0.07-1.0 microns, then a Pd core is impregnated to form an activation point on the surface and in the hole of the base film, the steps of calcining, chemical plating and direct vacuum heat treatment are carried out, the steps of impregnating the Pd core, calcining and chemical plating can be repeatedly carried out, and the chemical plating solution contains 0.01-1% (volume) of surfactant, so that the ceramic metal composite film is obtained. The palladium-silver activated points are not only formed on the surface of the base film, but also mainly formed in the pores, and a part of the prepared palladium-silver film enters the pores of the base film.

A strip-shaped ceramic metal composite membrane and a stainless steel sleeve form a membrane reactor, the inner cavity of the ceramic tube is a permeation cavity, a reaction cavity is formed between the ceramic tube and the stainless steel sleeve, a catalyst, namely a commercially available copper catalyst, is filled in the reaction cavity, methanol steam enters the reaction cavity and is decomposed to produce hydrogen under the action of the catalyst, and the reaction formula is as follows:

the total reaction is as follows:

the molar ratio of the raw material water to the methanol is 1.0-2.5, preferably: 1.0 to 1.3.

The reactiontemperature is 150-300 deg.C, preferably 250-300 deg.C

Reaction chamber pressure: 0 to 4MPa (gauge pressure), preferably: 0.2 to 1.5MPa (gauge pressure)

Osmotic chamber pressure: -0.2 to 0.5MPa (gauge pressure), preferably: 0 to 0.1MPa (gauge pressure)

The catalyst and the raw materials in the reaction cavity are replaced, so that the device can be suitable for other hydrogen production reactions, such as ammonia decomposition reaction, hydrazine decomposition reaction, hydrocarbon steam conversion hydrogen production reaction and the like.

The ceramic metal composite membrane of the invention has the advantages that the metal layer is firmly combined with the matrix, the metal layer is an ultrathin layer, the internal stress is small, so that pure hydrogen is separated at the temperature of 150-300 ℃ lower than the hydrogen embrittlement temperature, and the permeation quantity reaches 60-150 ml/cm²·min·atm^1/2The method has the advantages of no hydrogen embrittlement or breakage after continuous use for more than 1000 hours, 80% hydrogen yield, 90% hydrogen recovery rate, reduced reaction temperature, low energy consumption, synchronous reaction and separation, convenient operation and less equipment investment. The invention breaks through the convention that the hydrogen production of the ceramic metal composite membrane can only be carried out at the temperature of more than 300 ℃, the purity of the hydrogen produced in the reaction reaches 100 percent, and the scale of the produced gas is 11-1 m³/h。

FIG. 1 is a membrane reactor configuration;

FIG. 2 is a hydrogen production flow diagram;

FIG. 3 is a 1000 hour reaction diagram;

FIG. 4 shows hydrogen conversion at various feed rates and pressures.1. Raw materials (methanol + water); 2. pure H₂(ii) a 3. A seal ring; 4. a catalyst; 5. a thermocouple; 6. a ceramic metal composite membrane; mixed gas of N2 + H2 (reduction catalyst); 8, N2; 9. methanol + water mixed raw material; 10. a rotameter; 11. a metering pump; 12. a preheater; 13. a heater; 14. a membrane reactor; 15. a wet flow meter; 16. a cooler; 17. a pressure gauge; GC: a gas column chromatograph; t: hours; p: pressure (unit 0.1 MPa); r: conversion rate; d: the purity of hydrogen.

The following is further described in conjunction with the examples and the figures:

EXAMPLE 1 preparation of ceramic-Pd composite membranes

A commercially available cylindrical ceramic tube with a thickness of 1mm, an inner diameter of 18mm and a length of 400mm and a closed end is taken, washed with dilute alkali solution (KOH, 0.1N), boiled in boiling distilled water for 30 minutes and dried at 100 ℃ for 6 hours. Preparing 0.2N PdCl₂Adding 10ml of 1N HCl solution into the solution, and placing the treated ceramic substrate tube on the PdCl₂Soaking in solution at room temperature for 15 hr, taking out, calcining at 650 deg.C for 5 hr, drying, cooling, chemically plating Pd in prepared plating solution at 30 deg.C for 2b, vacuum-pumping at 200 deg.C, and placing in PdCl₂Soaking in the solution for 10 hours, roasting at 650 ℃ for 5 hours, drying, cooling, chemically plating Pd3 hours, and processing at 200 ℃ under vacuum to obtain the ceramic-Pd composite membrane with the Pd membrane thickness of 3 microns.

The plating solution comprises the following components: PdCl₂6g/l，EDTA67g/L，NH₃·H₂O350ml/L，N₂NNH₂0.5ml/L, surfactant: 1% by volume of sodium + ethanesulfonate.

The prepared ceramic-Pd composite membrane has an effective area of 70cm²At 300 ℃ H₂The permeation volume is 80ml/cm²·min·atm^1/2Separation of H at 150 ℃₂No hydrogen embrittlement occurs because the Pd membrane is firmly combined with the pore matrix, the mechanical strength is increased, the metal layer is thin, and the internal stress is small.

EXAMPLE 2 preparation of ceramic-Pd-Ag composite film

Taking a commercially available cylindrical ceramic tube with the thickness of 1mm, the inner diameter of 18mm and the length of 350mm and one end sealed, carrying out surface treatment on a base film, dipping Pd particles, calcining, chemically plating and the like under the same conditions as in example 1, wherein the composition of a Pd plating solution is the same, after chemically plating Pd, chemically plating Ag by using an Ag plating solution at the temperature of 30 ℃ for 5 hours, then placing the tube in the Pd plating solution for chemically plating Pd2 hours, and carrying out vacuum heat treatment for 8 hours at the temperature of 850 ℃ to obtain the ceramic-Pd-Ag composite film.

The Ag plating solution comprises the following components:

[Pd(NH₃)₄]Cl₂·H₂O0.5g/l

AgNO₃5g/l

EDTA 36g/l

NH₃H₂O 400ml/l

H₂NNH₂0.5ml/l was determined by a change in the composition of the plating solution whether the desired Pd-Ag ratio was achieved.

The ceramic-Pd-Ag membrane obtained by the method has an effective membrane area of 60cm²The film thickness is 10 μm, and the permeability to H is at 300 DEG C₂The amount is: 65ml/cm²·min·atm^1/2No hydrogen embrittlement occurred at 250 ℃.

Example 3 Membrane reactor

As shown in figure 1, the inner pipe of the ceramic metal composite membrane pipe 6 forms a permeation cavity, a stainless steel pipe 7 concentric with the composite membrane pipe is used as the wall of the reactor, the stainless steel pipe and the composite membrane pipe are sealed by an O-shaped ring 3 to form a reaction cavity, and a commercially available copper catalyst 4 is filled in the reaction cavity to form the membrane reactor, which is shown in figure 2.

Example 4

A reaction device is constructed as shown in figure 1, the membrane reactor of the embodiment 3 is adopted, the ceramic Ag composite membrane of the embodiment 2 is adopted, a group of heaters are arranged outside the reactor, the reaction temperature is 300 ℃, the pressure of a reaction cavity is 0.8MPa, the methanol feeding is 45g/h, the water-methanol molar ratio is 1: 1, the conversion rate of the methanol is 80%, the hydrogen recovery rate is 90%, and the purity of the product hydrogen reaches 100%.

The calculation formula is as follows:

example 5 Life test

Taking the ceramic-Pd composite membrane tube in example 1, the tube length is 450mm, and the effective membrane area is 65cm²The membrane permeation amount is 67ml/cm²·min·atm^1/2A membrane reactor was assembled as in example 3, the apparatus was set up as in example 4, the amount of catalyst was 50g, the methanol feed amount was 30g/H, the molar ratio of water to methanol was 1: 1, the pressure in the reaction chamber was 0.4MPa, and the pressure in the permeation chamber was 0, and the reaction was carried out at 300 ℃ for 1000 hours, as a result, as shown below, in the permeation chamber H₂Purity is plotted against time, see FIG. 3.

Example 6 examination of conditions

A membrane reactor was constructed in the same manner as in example 5, and the influence of different reaction pressures and methanol feed amounts on the conversion rate was examined, wherein the methanol feed amounts were 54g/h, 70g/h, and 100g/h, respectively, the reaction pressure was in the range of 0 to 1.5MPa (gauge pressure), the methanol conversion rate gap pressure increased and increased, and the methanol conversion rate decreased with the increase in the feed amount under the same pressure, as shown in FIG. 4.

Example 7

The device was constructed in the same manner as in example 5, and the low temperature performance of the membrane at 250 ℃ was examined, the methanol feed rate was 65g/h and 100g/h, and after 100 hours of stable operation, the membrane tube was removed, and no hydrogen embrittlement or rupture was observed.

Claims

1. The utility model provides a reactor of ceramic metal complex film for hydrogen production is changeed to methanol steam, its characterized in that palladium silver metallic film thickness that the used ceramic substrate tube of reactor plated is 1 ~ 10 mu m, and the palladium silver content of constituteing the metallic film is palladium 70 ~ 100%, silver respectively: 0 to 30 percent.

2. The production of a reactor according to claim 1, wherein the palladium-silver active sites are formed not only on the surface of the base film but also mainly in the pores, and a part of the produced palladium-silver film is taken into the pores of the base film.

3. An application method for producing hydrogen by using the ceramic-metal composite membrane reactor of claim 1, wherein a methanol decomposition hydrogen production reaction catalyst is filled in the reactor, and is characterized in that the reaction temperature is 250-300 ℃, the pressure of a reaction cavity is 0.1-2.0 MPa, and the pressure of a permeation cavity is 0-0.5 MPa.