CN100341610C

CN100341610C - Improved method for preparing palladium supported membrane by photocatalytic sedimentation

Info

Publication number: CN100341610C
Application number: CNB2005100388022A
Authority: CN
Inventors: 徐南平; 范益群; 李雪
Original assignee: Nanjing Tech University
Current assignee: Nanjing Tech University
Priority date: 2005-04-11
Filing date: 2005-04-11
Publication date: 2007-10-10
Anticipated expiration: 2025-04-11
Also published as: CN1698940A

Abstract

The present invention relates to an improved method for preparing a carried palladium film by means of photocatalytic deposition. Single palladium salt is simultaneously added to copper salt or silver salt and is dissolved in a water solution containing methyl alcohol, or ethyl alcohol, or normal propyl alcohol, and the pH value of the water solution is adjusted to be from 2 to 5. An inorganic ceramic supporter is immersed into the solution to lead a liquid film is attached to the surface of a base film, wherein the anatase crystal type titanium dioxide base film is precoated on the surface of one side of the inorganic ceramic supporter. Subsequently, the supporter is integrally or partial lifted off the liquid level, and the liquid film on the surface of the base film, which leaves the liquid level, is irrigated by ultraviolet light. Thus, the palladium salt in the surface liquid film generates the photocatalytic reaction and is reduced into a palladium film or a palladium alloy film. The course is repeated until the thickness of the palladium film reaches the desired thickness, and the surface of the film is flushed by ionized water. After the surface of the film is dried, the carried palladium or the palladium alloy film is prepared. The photocatalytic reaction of the present invention can be carried out on the liquid film which disengages from a solution system; the negative effects to the quality of the palladium film, which are caused by homogeneous reactions and the introduction of impurities in the solution, are avoided; an ultrathin palladium film below 0.4 mu m can be prepared.

Description

The method of improved preparing palladium supported membrane by photocatalytic sedimentation

Technical field

The present invention relates to a kind of palladium of hydrogen separation or preparation method of palladium alloy membrane of being used for, particularly adopt photo catalytic reduction to prepare the method for carried palladium film.

Background technology

Metal Palladium (comprising palladium copper, palladium-silver, down together) is the high membrane material of a kind of hydrogen permeation selectivity, can be used for Hydrogen Separation and hydrogen purification.The palladium film that supports with porous supporting body can improve the mechanical strength of film and can reduce cost, and generally can make by galvanoplastic, physical vaporous deposition, chemical vapour deposition technique, electroless plating method etc.Also there is bibliographical information to utilize laser to prepare the Metal Palladium film, as LCVD, PECVD method, but the expensive vacuum equipment of this Technology Need, and raw material is rare organometallic precursor.CN 99114034.6 patent disclosures a kind of method that adopts photocatalytic deposition to prepare the Metal Palladium film, the surface is scribbled TiO ₂The ceramic supporting body of basement membrane impregnated in the palladium ion solution, penetrates by illumination to make the palladium ion reduce deposition get carried palladium film in membrane surface.But in the course of reaction, the catalytic action meeting of ultraviolet light impels liquid-phase system that complicated decomposition reaction takes place, and the part palladium ion directly deposits in the liquid phase main body, cause the palladium loss, thereby the palladium film that forms is not fine and close, generally need further modify by electroless plating method, has increased operation.

Summary of the invention

The purpose of this invention is to provide a kind of improved carried palladium film photocatalysis preparation method, it not only can prepare ultra-thin compact metal palladium film, and preparation process is simple, is suitable for large-scale production.

The present invention adopts following steps:

By the concentration of 0.02-0.8g/l single palladium salt or palladium salt and mantoquita or palladium salt and silver salt mixture are dissolved in the aqueous solution that contains organic additive, said organic additive is selected from methyl alcohol, ethanol or normal propyl alcohol, the volumetric concentration of said additive in solution is 10-80%, regulator solution pH value 2-5, the inorganic ceramic supporter that one side surface precoating is covered with anatase crystal titanium dioxide basement membrane immerses in the solution, make membrane surface enclose liquid film, subsequently with all or part of liquid level of lifting from of supporter, liquid film to the membrane surface of leaving liquid level carries out UV-irradiation, the slaine generation light-catalyzed reaction in the liquid film and be reduced to metal Pd or alloy Pd/Cu, Pd/Ag is deposited on the surface of titanium dioxide basement membrane; Go into to soak more than the repetition-lift from-light-catalyzed reaction process to palladium or palladium alloy membrane reach desired thickness, washes membrane surface repeatedly with deionized water, after the drying carried palladium film or palladium alloy membrane.

Said supporter is the plates that a side is coated with the titanium dioxide basement membrane, after immersing solution it is all lifted from solution system, surperficial liquid film to basement membrane one side under vacant state carries out UV-irradiation, repeats to shine 10-30 minute into soaking-lifting from 4-8 time at every turn.

Said supporter is the tubular body that outer wall or inner wall tube precoating are covered with titania-based film, after immersing solution body is partly lifted from solution system with level, body forms liquid film in the mode of slow rotation, and with ultraviolet light the basement membrane one side surface liquid film that surfaces is continued to carry out UV-irradiation simultaneously.

The inventive method can make the palladium film of film thickness instrument 0.2-2 μ m, and the smooth densification of film surface is compared with existing method and to be had the following advantages:

1. reaction is at room temperature carried out, and does not need reaction atmosphere, has saved equipment investment, and energy savings also can effectively be controlled reaction speed;

2. avoid the negative effect of the palladium film quality that introducing brought of the generation of homogeneous reaction in the solution and impurity;

3. reaction solution can use for a long time repeatedly, and the abundant reduce deposition of palladium ion reduces reaction cost in supporting body surface under the UV-irradiation;

4. prepared palladium film thickness is very thin, and the fine and close zero defect of film surface, so hydrogen and selectivity can significantly improve.

5. it is simple to adopt this method to prepare the palladium membrane process, is suitable for large-scale production.

Description of drawings

Fig. 1 is the TiO of depositing Pd film not ₂The X-ray diffraction spectrogram of basement membrane.

Fig. 2 is ESEM (SEM) result on the prepared carried palladium film surface of the inventive method.

Fig. 3 (a) is prepared carried palladium film profile scanning Electronic Speculum (SEM) figure of the inventive method,

Fig. 3 (b) is prepared carried palladium film section electron spectroscopy analysis (EDS) result of the inventive method.

Fig. 4 is X-ray diffraction analysis (XRD) result on the surface of the prepared carried palladium film of the inventive method.

Fig. 5 is X ray electron spectrum (XPS) result on the surface of the prepared carried palladium film of the inventive method.

Among Fig. 1, A represents Detitanium-ore-type TiO ₂The peak, a represents α-Al ₂O ₃The peak, as seen from Figure 1, TiO ₂The basement membrane crystal formation is simple Detitanium-ore-type, can be used for the Metal Palladium film that the preparation of photocatalytic deposition method supports.

The visible TiO of Fig. 2 ₂The surface of basement membrane has formed by the inventive method prepared palladium membrane.

Light among Fig. 3 (a) is represented the palladium rete, and darker curve and lighter curve are represented Pd and TiO respectively from Fig. 3 (b) ₂The electron spectrum curve, to make its surperficial elemental composition of carried palladium film mainly be palladium and titanium in the present invention as can be known, the thickness of palladium film is about 0.4 μ m.

Fig. 4 is X-ray diffraction analysis (XRD) result on the surface of the prepared carried palladium film of the inventive method, further illustrates at TiO ₂The surface of basement membrane has formed very thin palladium rete.

Fig. 5 is X ray electron spectrum (XPS) analysis result on the surface of the prepared carried palladium film of the present invention, to pollute carbon binding energy is carried out charged correction, obtains Δ E _{Proofread and correct}=15.35ev; The characteristic spectral line position of corresponding diagram 5 palladiums, the binding energy behind the calculation correction are 334.95ev.Contrast with the standard value in the PHI5300 ESCA database, can determine that the palladium element is present on the titanium dioxide basement membrane with pure simple substance form.

The specific embodiment

Embodiment one: support the preparation of chip palladium film

Adopting physical dimension is diameter 29mm, α-Al of thickness 3mm ₂O ₃The chip supporter is by the TiO of wet chemistry method to supporter one side coating anatase crystal ₂Basement membrane (preparation method sees Chinese patent CN03113127.1).With PdCl ₂0.02g, absolute methanol solution 50ml, distilled water 450ml is mixed with solution, and solution is 5 with rare nitre acid for adjusting pH value; To scribble TiO ₂The chip supporter of basement membrane floods in reactant liquor, then supporter is lifted from solution system and is hung in the sky, and supporter its surface in the process of lifting forms liquid film, at ambient temperature supporter is had TiO ₂The liquid film of one side directly carried out ultra violet lamp 10 minutes; Light source adopts the 150w mercury lamp, and palladium ion is deposited on membrane surface through photo catalytic reduction, forms the palladium film.Above repeatedly dipping and illumination process 4 times, after the sheet Pd film that obtains supporting after the rinsing repeatedly, thickness is 0.4 μ m.

In the present embodiment, change the slaine of above-mentioned adding into Pd (NO ₃) ₂0.08g, CuCl ₂0.01-0.04g, make the Pd/Cu alloy film.

Change the slaine that adds into Pd (NO ₃) ₂0.08g, Ag (NO ₃) ₂0.01-0.06g, make the Pd/Cu alloy film.

Embodiment two: support the preparation of tubular type palladium film

Adopt α-Al ₂O ₃Tubular support (calling the film pipe in the following text), its physical dimension is external diameter 12mm, wall thickness is 1.5mm, long 33cm.Film Guan Yiduan seals with glaze, the lateral surface (being the outer wall of tubular body) of film pipe is applied the TiO of anatase crystal by wet chemistry method ₂Basement membrane.Then the film pipe is immersed in the solution of embodiment one, make the film pipe partly lift from solution system again with level, at ambient temperature with ultraviolet light to surface the membrane surface liquid film carry out UV-irradiation, body carries out the process that forms liquid film and carry out UV-irradiation in the mode of slow rotation continuously, and the palladium thickness of film pipe is about 0.3 μ m.

Claims

1. the method for improved preparing palladium supported membrane by photocatalytic sedimentation is characterized in that adopting following steps:

By the concentration of 0.02-0.8g/l with single palladium salt or simultaneously palladium salt and mantoquita or palladium salt and silver salt are dissolved in the aqueous solution that contains organic additive, said organic additive is selected from methyl alcohol, ethanol or normal propyl alcohol, the volumetric concentration of additive in solution is 10-80%, regulator solution pH value 2-5, the inorganic ceramic supporter that one side surface precoating is covered with anatase crystal titanium dioxide basement membrane immerses in the solution, make membrane surface enclose liquid film, subsequently with all or part of liquid level of lifting from of supporter, liquid film to the membrane surface of leaving liquid level carries out UV-irradiation, slaine generation light-catalyzed reaction and be reduced to metal Pd or alloy Pd/Cu, Pd/Ag is deposited on the surface of titanium dioxide basement membrane; Go into to soak more than the repetition-lift from light-catalyzed reaction process to palladium or palladium alloy membrane and reach desired thickness, wash membrane surface repeatedly with deionized water, after the drying carried palladium film or palladium alloy membrane.

2, the method of improved preparing palladium supported membrane by photocatalytic sedimentation according to claim 1, it is characterized in that supporter is the plates that a side scribbles the titanium dioxide basement membrane, after immersing solution it is all lifted from solution system, surperficial liquid film to basement membrane one side under vacant state carries out UV-irradiation, repeat 4-8 time, shone 10-30 minute at every turn.

3. the method for improved preparing palladium supported membrane by photocatalytic sedimentation according to claim 1, it is characterized in that said supporter is the tubular body that outer wall or inwall precoating are covered with titania-based film, after immersing solution body is partly lifted from solution system with level, body forms liquid film in the mode of slow rotation, and with ultraviolet light the basement membrane one side surface liquid film that surfaces is continued to carry out UV-irradiation simultaneously.