| Summary: |
Since 1989 CO is separated/recovered by pressure swing adsorption (PSA) using supported CuCl adsorbents. CO is typically produced along with hydrogen as synthesis gas, by steam reforming of methane or naphtha. CO happens also as a by product from the steam reforming of various hydrocarbons for producing hydrogen to fuel cells. Hydrogen fuel cells are able to produce more efficiently energy without virtually polluting the air. The so-called well-to-wheels energy efficiency puts hydrogen fuel cells with hydrogen obtained from stream reforming at the top of a series of state of the art solutions and in second place for the technology which emits less greenhouse gases. Hydrogen fuel cells/steam reforming is being investigated for supply with electrical energy commercial airplanes, with favourable impact in the airports noise and air pollution.
Up to very recently, most commercially available membranes for gas separations were polymeric. Polymeric membranes show low to medium selectivities and permeabilities and can operate only in mild conditions. The development of molecular sieve membranes, with pores in the nanometric range, started about two decades ago, with the pioneering work by Soffer (carbon molecular sieve membranes) and by Barrer and Suzuki (zeolite membranes). These two membrane families are expected to exhibit simultaneously higher permeabilities and selectivities when compared with polymeric membranes.
The aim of the present project is to develop a new class of ceramic ultramicroporous membranes, containing fixed site carriers. There are very few publications on ceramic ultramicroporous facilitate membranes as showed by a carefully search in the ISI Web of Science. The carrier which will be used is CuCl-ceramic (alumina) and Cu(I)-zeolite (NaY and 13X) membranes [1]. Both were reported to be good for PSA removal/separation of CO from a gas stream containing methane and hydrogen. These absorbents are not deactivated in presence of hydrogen sulphide or  |
Summary
Since 1989 CO is separated/recovered by pressure swing adsorption (PSA) using supported CuCl adsorbents. CO is typically produced along with hydrogen as synthesis gas, by steam reforming of methane or naphtha. CO happens also as a by product from the steam reforming of various hydrocarbons for producing hydrogen to fuel cells. Hydrogen fuel cells are able to produce more efficiently energy without virtually polluting the air. The so-called well-to-wheels energy efficiency puts hydrogen fuel cells with hydrogen obtained from stream reforming at the top of a series of state of the art solutions and in second place for the technology which emits less greenhouse gases. Hydrogen fuel cells/steam reforming is being investigated for supply with electrical energy commercial airplanes, with favourable impact in the airports noise and air pollution.
Up to very recently, most commercially available membranes for gas separations were polymeric. Polymeric membranes show low to medium selectivities and permeabilities and can operate only in mild conditions. The development of molecular sieve membranes, with pores in the nanometric range, started about two decades ago, with the pioneering work by Soffer (carbon molecular sieve membranes) and by Barrer and Suzuki (zeolite membranes). These two membrane families are expected to exhibit simultaneously higher permeabilities and selectivities when compared with polymeric membranes.
The aim of the present project is to develop a new class of ceramic ultramicroporous membranes, containing fixed site carriers. There are very few publications on ceramic ultramicroporous facilitate membranes as showed by a carefully search in the ISI Web of Science. The carrier which will be used is CuCl-ceramic (alumina) and Cu(I)-zeolite (NaY and 13X) membranes [1]. Both were reported to be good for PSA removal/separation of CO from a gas stream containing methane and hydrogen. These absorbents are not deactivated in presence of hydrogen sulphide or moisture. For low pressures, 100 mbar, and at ambient temperature the adsorption selectivity of CO over hydrogen on a monolayer covered CuCl/NaY zeolite is extremely high. It is expected then that both CO permeability and permselectivity are very high although hydrogen is a lighter molecule. A membrane with such characteristics can find applications on removing CO from hydrogen streams (e.g. for fuel cells) or for CO separation, replacing PSA technology specially for low flowrates and purity, following a similar path to the nitrogen market, which is now strongly shared by membrane technology.
The CO permeation flowrate and selectivity increase if its concentration in the permeate side is maintained very low. This can be attained by reacting the emerging CO with oxygen. This is the second objective of the present project, to develop a fixed site carrier catalytic ultramicroporous ceramic membrane reactor. |