Zeolite Membranes: Novel Synthesis and Innovative Applications

Dear Colleagues,

Zeolites are microporous materials that possess molecular sieving and selective adsorption properties, the preparation of a zeolite membrane opens up the possibility of working in a continuous process, furthermore a zeolite film would be desirable in several applications such as structured reactors or sensors.Since the first synthesis of a zeolite membrane in 1986, many milestones have been achieved. The preparation of a “defect free” zeolite layer, for gas separation, was the first and is still a matter of study. The control of the orientation of the zeolite crystals was accomplished by secondary growth and the use of organic structure-directing agents. An important success was accomplished in 2001 when the first industrial application of zeolites was introduced, the pervaporation of water/alcohol mixtures. Concerning applications, apart from gas separation and pervaporation, membrane reactors have also been an attractive research topic.

The most studied zeolite membranes are indeed the MFI and LTA frameworks; however there is still a research effort for other zeotypes and new materials related such as titanosilicates, aluminophosphates or recently the microporous metal organic frameworks.

In the last five years many efforts have been devoted to the synthesis of hybrid or mixed matrix membranes. The assembly of nanozeolite building blocks and nanosheets is also the starting point, for the synthesis of thin defect free zeolite membranes. The ultrafast synthesis of zeolites in microwave has contributed to prevent the dissolution of the support. These new synthesis methods and new materials will be covered in this special issue.

Considering the difficulty to prepare high areas of defect free zeolite membranes, innovative applications that include zeolite films or small scale applications such as microreactors, micromembranes, sensors, films for controlled permeation or coatings are being explored in the last few years.

Dr. Reyes Mallada
Guest Editor