Studies of Aluminum Reinsertion into Borosilicate Zeolites with Intersecting Channels of 10- and 12-Ring Channel Systems

The work here describes the kinetic analyses of aluminum replacement for boron in a suite of borosilicate molecular sieves. While the method has been described before as a means of converting synthesized borosilicates (with weak inherent acidity) to aluminosilicates (with much stronger acid strength) when there are large pores in the structure, here we carry out the transformation under less than optimal replacement concentrations, in order to better follow the kinetics. We examined several zeolite structures with boundary conditions of boron MEL where there are only 10-ring (or intermediate) pore structures and no Al is taken up, to multidimensional large pore zeolites, like boron beta, where Al substitution can occur everywhere. We also studied materials with both intermediate and large pores, SSZ-56, 57, 70, and 82. In the case of 57 up to 90% of the structure is made up of boron MEL. We observe that the pH drop is proportional to the Al reinsertion and is the same for all zeolites we studied. In one case, we compared a zeolite (SSZ-24) with boron and then no boron sites and found that Al does not go into defect sites. It was again confirmed (shown in earlier work) that Al will go into nest sites created by boron hydrolysis out of the substrate before Al treatment. Along those lines we also made two new observations: (1) the profile for Al uptake, as followed by pH drop, is the same kinetically, whether the boron is there or not; and (2) NMR showed that the boron is leaving the structure faster than Al can go back in (SSZ-33 study), even when we treat a material with boron in the lattice

Studies of Aluminum Reinsertion into Borosilicate Zeolites with Intersecting Channels of 10- and 12-Ring Channel Systems

The work here describes the kinetic analyses of aluminum replacement for boron in a suite of borosilicate molecular sieves. While the method has been described before as a means of converting synthesized borosilicates (with weak inherent acidity) to aluminosilicates (with much stronger acid strength) when there are large pores in the structure, here we carry out the transformation under less than optimal replacement concentrations, in order to better follow the kinetics. We examined several zeolite structures with boundary conditions of boron MEL where there are only 10-ring (or intermediate) pore structures and no Al is taken up, to multidimensional large pore zeolites, like boron beta, where Al substitution can occur everywhere. We also studied materials with both intermediate and large pores, SSZ-56, 57, 70, and 82. In the case of 57 up to 90% of the structure is made up of boron MEL. We observe that the pH drop is proportional to the Al reinsertion and is the same for all zeolites we studied. In one case, we compared a zeolite (SSZ-24) with boron and then no boron sites and found that Al does not go into defect sites. It was again confirmed (shown in earlier work) that Al will go into nest sites created by boron hydrolysis out of the substrate before Al treatment. Along those lines we also made two new observations: (1) the profile for Al uptake, as followed by pH drop, is the same kinetically, whether the boron is there or not; and (2) NMR showed that the boron is leaving the structure faster than Al can go back in (SSZ-33 study), even when we treat a material with boron in the lattice

Development of a Semiautomated Zero Length Column Technique for Carbon Capture Applications:Rapid Capacity Ranking of Novel Adsorbents

A novel zero length column (ZLC) apparatus has been developed to provide rapid screening of CO₂ capacities of adsorbent materials. The key features of the new apparatus are the use of 5–15 mg of sample, a purposely designed gas-dosing system, and low flow rates that extend the use of the ZLC to test adsorbents for postcombustion for carbon capture applications. The new ZLC system was first applied to provide rapid screening capacity ranking of more than 15 MOF materials and three representative zeolites. At the point of interest for flue gas application (38 °C, 0.1 bar CO₂ partial pressure), Mg/DOBDC was found to outperform significantly all other MOFs and the benchmark zeolites

Synthesis and structural characterization of Zn-containing DAF-1

A study exploring the use of ionic liquid reactions based on imidazolium halides in molecular sieve synthesis has produced a novel zincoaluminophosphate material with an open DFO-type framework structure. This framework structure had only been observed previously in the magnesioaluminophosphate system (Mg-DAF-1) where decamethonium was used as the structure directing agent. The new Zn-DAF-1 material has been characterized using chemical and thermogravimetric analysis and ^(13)C, ^(19)F, ^(27)Al and ^(31)P MAS NMR techniques. Structure analysis (P6/mcc, a = 22.2244(1) Å, c = 42.3293(3) Å) using synchrotron powder diffraction data not only confirmed the framework structure, but also revealed the locations of the Al, P and Zn atoms in the framework, the N,N′-di-isopropyl-imidazolium (DIPI) ions in the pores, some fluoride ions associated with double 4-rings, and some water molecules and anions filling the remaining space. This level of structural detail had not been possible in the Mg-DAF-1 material. Four different locations for the DIPI cation were found in the two 12-ring channels and Zn was found to substitute for only one of the six crystallographically distinct Al sites to yield the approximate crystal chemical formula |(DIPI)_(17)(OH,F)_(11)(H2O)_(23)|[Zn_6Al_(126)P_(132)O_(528)]-DFO

Synthesis and structural characterization of Zn-containing DAF-1

A study exploring the use of ionic liquid reactions based on imidazolium halides in molecular sieve synthesis has produced a novel zincoaluminophosphate material with an open DFO-type framework structure. This framework structure had only been observed previously in the magnesioaluminophosphate system (Mg-DAF-1) where decamethonium was used as the structure directing agent. The new Zn-DAF-1 material has been characterized using chemical and thermogravimetric analysis and ^(13)C, ^(19)F, ^(27)Al and ^(31)P MAS NMR techniques. Structure analysis (P6/mcc, a = 22.2244(1) Å, c = 42.3293(3) Å) using synchrotron powder diffraction data not only confirmed the framework structure, but also revealed the locations of the Al, P and Zn atoms in the framework, the N,N′-di-isopropyl-imidazolium (DIPI) ions in the pores, some fluoride ions associated with double 4-rings, and some water molecules and anions filling the remaining space. This level of structural detail had not been possible in the Mg-DAF-1 material. Four different locations for the DIPI cation were found in the two 12-ring channels and Zn was found to substitute for only one of the six crystallographically distinct Al sites to yield the approximate crystal chemical formula |(DIPI)_(17)(OH,F)_(11)(H2O)_(23)|[Zn_6Al_(126)P_(132)O_(528)]-DFO

Computationally Guided Synthesis of SSZ-52: A Zeolite for Engine Exhaust Clean-up

Computationally Guided Synthesis of SSZ-52: A Zeolite for Engine Exhaust Clean-u