[Sach]

So attempts have been done to combine advantages of homogeneous (high selectivity and activity) and heterogeneous (easy recovery) catalysts by grafting them for example on a porous surface. I did not completely understand this. My main question is, when you graft a homogeneous catalyst on a porous surface, will the reagents and catalyst be in the same phase (homogeneous) or will they be in different phases (heterogeneous)?

Thank you in advance guys, Tomorrow is my thesis defence and although my thesis is not about catalysis but I still saw this as a potential question. In the attachment you can find a picture of the statement from where I got this information.

[Enthalpy]

Maybe the catalyst is adsorbed on the surface? Strongly enough that it's removed after use together with the porous material?

[pgk]

It is clearly mentioned in the text that “the size of the pore needs to be just right”; neither smaller, nor larger.
This means that the liquid penetrates into the pores, wets the material by dissolving the molecules of catalyst that are grafted on the material but without de-grafting them and therefore, the catalysis can be considered as homogeneous. After the end of the reaction, the material with the grafted catalyst is washed and used again like an heterogeneous catalyst.
Try to imaging this at a microscopic/molecular level:
The molecules of the catalyst are hanged (grafted) on the inner surface of the cavity (pore), which has the adequate size (no more, not less), in order to be filled with an amount of liquid that contains only a couple of molecules of the reagents.
You can draw this on piece of paper. It will help you to understand it.
I wish you the best for your thesis and congratulations, in advance.

[Sach]

This explanation is so clear.
Thank you so much.