MESA+ University of Twente
Research Business & Innovation About MESA+ Education

Hien Duy Tong (promotion date: 4 June 2004)

Microfabricated Palladium Based Membranes for Hydrogen Separation

Promotion Date: 4 June 2004

Hien Duy Tong

We have utilized microfabrication techniques to develop new approaches for making both dense as well as porous membranes. The Pd-based membranes are fabricated and used as hydrogen purifiers to get high quality hydrogen, and as membrane reactors for several dehydrogenation reactions. We used palladium because of its unique properties to absorb huge amounts of hydrogen. On the surface of the membrane the palladium causes hydrogen to very quickly dissociate into hydrogen atoms, which diffuse through the Pd film. At the other side of the membrane hydrogen molecules are formed again. In this way, the Pd membrane stops almost all other gases and only hydrogen permeates, resulting in pure hydrogen at the other side of the membrane.

What was your thesis about?

We have utilized microfabrication techniques to develop new approaches for making both dense as well as porous membranes. The Pd-based membranes are fabricated and used as hydrogen purifiers to get high quality hydrogen, and as membrane reactors for several dehydrogenation reactions. We used palladium because of its unique properties to absorb huge amounts of hydrogen. On the surface of the membrane the palladium causes hydrogen to very quickly dissociate into hydrogen atoms, which diffuse through the Pd film. At the other side of the membrane hydrogen molecules are formed again. In this way, the Pd membrane stops almost all other gases and only hydrogen permeates, resulting in pure hydrogen at the other side of the membrane. Pure hydrogen is a very important chemical for a lot of things, like fuel for fuel cells for instance. Also hydrogen is used for material processing and in metallurgical technology. But the main result of my thesis is the microfabrication of this very thin but defect free palladium-based membrane.

Was there never another way to obtain pure hydrogen?

Oh, yes, there are a lot of ways to obtain pure hydrogen, but a lot of these technologies are too expensive. Membrane technology is supposed to be far cheaper.

So this is very important to industry?

You could say that. There is even talk nowadays of the ‘hydrogen economy’ using hydrogen as a fuel for the running of cars and buses. Even today some buses run on hydrogen: hydrogen and oxygen release a clean electric power and the only waste product is water.

The burning of oil, a hydrocarbon, result in the well-known problems with the emission gases.

Also economies are too dependent on oil. So hydrogen is one of alternatively future energy carriers, but there are still enormous difficulties to overcome: the manufacturing of hydrogen cars is still expensive, the distribution and other hydrogen related infrastructure, like tanks etcetera, is still a long way of. Ten years ago the US government initiated a huge hydrogen programme, which aimed at using hydrogen as a main energy carrier in coming two to three decades. Our research of course relates to the hydrogen programme, but it is still only a laboratory technique. Although it may separate hydrogen relatively cheap it is still too expensive for wide application. More research is necessary for that, but you will find that as soon as the oil prices drop again, the interest in a new, clean technology deteriorates.

What is your background, are you a chemist?

I did several things, first I studied chemistry in Vietnam and I got an engineering degree from Hanoi University of Technology. After that I continued to study semiconductor materials at ITIMS. ITIMS is funded by the Dutch government (Nuffic) and I got a scholarship to come to study here.

What will you do after your promotion?

Before I will go into that, I’ll tell you something else first. When talking about membranes most people thinks about separation of gases and liquids, and that is it. But membranes can be applied for other purposes as well, nanotechnology for instance, making nanodots and nanowires. And this relates to my future plan; using membranes as templates for the creating of nanostructures, which is cheaper than lithography and takes less time and effort.

Where are you going to carry out your future plans, here or in Vietnam?

I am going to continue with some ideas in my current group for another year. Then I would like to go somewhere else for one or two years and then return to Vietnam. My wife and I would like to be back in Vietnam before the time my little daughter has to go to school. One year before that will give her time to adapt to a new environment. She is now only eight months old, so that gives us still a bit of time.