JPS60177554A - Catalyst for phosphoric acid type fuel cell - Google Patents

Abstract

PURPOSE:To obtain a catalyst having high catalytic activity, high gas-permeability, and good discharge performance by alloying a specified amount of Pt with Pd. CONSTITUTION:A Pd-Pt alloy prepared by alloying 5-15wt% Pt with Pd. For example, Pd-Pt alloy powder prepared by adding 10wt% Pt with Pd is baked on a carbon electrode to form a catalyst layer. This catalyst has high catalitic activity since Pt is uniformly dispersed in molecular state, high gas-permeability since it mainly consists of Pd, and good discharge performance. Moreover, since the catalyst is not expensive, it can replace traditional Pt catalyst or Pt alloy catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in catalysts for phosphoric acid fuel cells.

The basic principle of a fuel cell is to electrochemically react H2 and 02 using a reaction opposite to the electrolysis of water to generate water and directly generate electricity. A catalyst is required for this reaction.

The fuel cell main body has an electrolyte matrix sandwiched between porous carbon electrodes, and a PT alloy catalyst is generally supported on both carbon electrodes. Elements having a structure such that 02 and I(z are stored respectively) are arranged on both electrode sides of the fuel cell main body.

Depending on the type of electrolyte sealed in the electrolyte matrix, fuel cells are either alkaline type or phosphoric acid type.

There are molten carbonate type, solid electrolyte type, etc., but especially in phosphoric acid type fuel cells, the activation polarization in electrode reaction is large, so
In order to reduce this, it is essential to use an active electrode catalyst, and PT is indispensable as a catalyst.

Incidentally, although PT has a high catalytic activity, the storage of H2 is approximately 100 times its volume, and its discharge characteristics cannot be said to be fully satisfactory. In order to improve the discharge characteristics, it is sufficient to increase the amount of PT catalyst, but since PT is expensive, research is being conducted on various electrode materials in order to avoid reducing the amount of catalyst.

In view of these circumstances, the present invention has conducted intensive research to develop a catalyst for phosphoric acid fuel cells that has high catalytic activity, high gas permeability, and excellent discharge characteristics, and as a result has found a catalyst that is generally satisfactory. Ta.

The phosphoric acid fuel cell catalyst of the present invention contains 5 to 5 pt of Pd.
It is made of a Pd-Pt alloy alloyed by adding 15% and 1t%.

The reason why Pd is used as a main component in the catalyst for phosphoric acid fuel cells of the present invention is that although the catalytic activity is lower than that of PT, the gas permeability is high because the occlusion of [12] is about 800% of the volume, and the discharge characteristics This is because it is extremely superior and moreover, it is cheaper than PT. Also, the reason why 5 to 15 wt% of pt was added to Pd to form an alloy was to disperse L, which has excellent catalytic activity, in a molecular state to make it work efficiently.
If it is less than 15 wt%, the catalytic action will be insufficient, and if it exceeds 15 wt%, the gas permeability will be low and the discharge characteristics will be insufficient.

Next, specific examples and conventional examples of the phosphoric acid fuel cell catalyst of the present invention will be described.

[Example 1] Pd alloyed by adding 10 ivt% of l)j to Pd
-PT gold alloy powder was baked onto a carbon electrode (0.50 mm thick) to form a 100 μm thick catalyst layer.

(Example 2) Pd-pt alloyed by adding 511t% of pt to Pd
A catalyst layer with a thickness of 10 μm was formed by plating on a gold alloy carbon electrode (0.50 wm thick).

[Example 3] Alloyed by adding 8 wt% of pt to Pd I) d −
A 150 μm foil made of PT gold alloy was connected to a carbon electrode (0,
50mm thick) to form a catalyst layer.

[Example 4] pd-p alloyed by adding 10 wt% of l)t to pd
A carbon electrode was impregnated with a solution of a gold alloy salt and reduced to support a Pd-Pt alloy catalyst.

[Conventional Example 1] PT powder was baked onto a carbon electrode (0.50 mm thick) to form a 100 μm thick catalyst layer.

[Conventional Example 2] PT was plated on a carbon electrode (0.50 mm thick) to form a catalyst layer with a thickness of 10 μm.

[Conventional Example 3] A 150 μm foil made of PT was connected to a carbon electrode (0.50μm).
A catalyst layer was formed by bonding the catalyst layer to the top of the catalyst (Ryu Atsushi).

[Conventional Example 4] A carbon electrode is impregnated with a solution of pt salt and reduced to pt.
t catalyst was used for tU.

However, the electrode catalysts of Examples 1 to 4 and Conventional Examples 1 to 4 were used as the negative electrode of a phosphoric acid fuel cell, and Pt-R)i was used as the positive electrode.
When electricity was generated using an electrode catalyst in which 5wt% alloy powder was baked onto a carbon electrode (0.50mm thick) to form a 100μm thick catalyst layer, electricity was generated as shown in the graph of Figure 1. i-sexuality was observed. As is clear from the graph of this diagram, the phosphoric acid fuel cells using the electrode catalysts of Examples 1 to 4 as the negative electrodes are compared with the phosphoric acid fuel cells using the conventional examples 1 to 4 electrode catalysts as the negative electrodes. It can be seen that it has excellent power generation characteristics.

This is simply because the electrode catalysts of Examples 1 to 4 used for the negative electrode have excellent catalytic activity, high gas permeability, and extremely excellent discharge characteristics.

As detailed above, the phosphoric acid fuel cell catalyst of the present invention is
Since pt is uniformly dispersed in Pd in molecular form, it has high catalytic activity, and since Pd is the main component, it has high gas permeability and extremely excellent discharge characteristics, and is inexpensive. PT or.

can be said to be an epoch-making product that can replace the PT gold alloy catalyst.

[Brief explanation of drawings]

FIG. 1 is a graph showing power generation characteristics of a phosphoric acid fuel cell using the Pd-Pt alloy catalyst of the present invention and a phosphoric acid fuel cell using a conventional PT catalyst. Applicant Tanaka Kikinzoku Kogyo Co., Ltd.

Claims (1)

[Claims] Pd- alloyed by adding 5 to 15 wt% of pt to Pd
A phosphoric acid fuel cell catalyst made of a PT gold alloy.