2-Isopropyl-1,3-dimethylimidazolium as a versatile structure-directing agent in the synthesis of zeolites.

An organic cation lacking specificity in its structure-directing action offers the possibility, through the screening of other structure-directing parameters, to synthesize a variety of zeolites. In this work we show that the organic structure-directing agent 2-isopropyl-1,3-dimethylimidazolium (2iPr13DMI) can produce up to seven different zeolite phases depending on water concentration, the presence of inorganic impurities, crystallization temperature and time, and germanium molar fraction. The obtained phases are very different in terms of pore system, connectivity of the zeolite structure and structural units.

Evaluation of metabolic syndromes and parasitic infection in Muscovy ducks under different management conditions.

Proper health management is essential for productivity in duck farming. However, there is limited information on the effect of management conditions on rates of metabolic problems and parasitic infections in anatids. We evaluated the rates of metabolic syndromes and gastrointestinal parasite involvement in Muscovy ducks up to 12 weeks of age, under 3 management conditions: backyard, organized, and organized with probiotics.

Mucilage and cellulosic derivatives as clarifiers for the improvement of the non-centrifugal sugar production process.

Non-centrifugal cane sugar (NCS) is the second most important Colombian agribusiness in social importance. However, the sugar cane industry is facing some challenges caused by the controversial nutritional and safety attributes of NCS. Some Colombian NCS producers employ natural mucilages as clarifiers; but the uncontrolled application of these components has caused a risk of extinction in the mucilage source plants.

Structure-direction in the crystallization of ITW zeolites using 2-ethyl-1,3,4-trimethylimidazolium.

2-Ethyl-1,3,4-trimethylimidazolium is so far the fifth and largest imidazolium cation able to produce the pure silica zeolite ITW. The crystallization is not direct, but occurs as an in situ transformation from either the chiral HPM-1 (STW) zeolite or the new layered zeolite precursor HPM-2 (preMTF) and results in large interpenetrated crystals with a habit so far unseen in this zeolite. The results of chemical, physicochemical and structural characterization allow us to discuss structure-direction issues.

Synthesis, structure, and optical activity of HPM-1, a pure silica chiral zeolite.

2-Ethyl-1,3,4-trimethylimidazolium is a poor organic structure-directing agent in the synthesis of pure silica zeolites using fluoride as a mineralizer at 150 °C. Under these conditions only ill-crystallized solids are obtained after long hydrothermal treatments (several weeks). It disappoints despite its relatively large size, conformational rigidity, and intermediate hydrophilic/hydrophobic character, attributes which would qualify it as a promising structure-directing agent, according to prior investigations.

Benzylimidazolium cations as zeolite structure-directing agents. Differences in performance brought about by a small change in size.

Two imidazolium cations containing a benzyl group, 1-benzyl-3-methylimidazolium and 1-benzyl-2,3-dimethylimidazolium, generally produce the large pore zeolite MTW when used as structure directing agents in the synthesis of pure silica zeolites by the fluoride route. When working at low water contents only the smallest of these cations is able to crystallize MFI, a zeolite with crossing medium pore channels. In that case, MFI is metastable towards MTW, but the in situ transformation slows down as the water content is decreased.

A pure silica chiral polymorph with helical pores.

A microporous polymorph of SiO(2), HPM-1, has a chiral structure and contains helical pores. The defect-free pure SiO(2) composition, which has been previously considered unfeasible for this structure type, bestows a high thermal and hydrothermal stability upon this material.

Zeolite structure direction by simple bis(methylimidazolium) cations: the effect of the spacer length on structure direction and of the imidazolium ring orientation on the 19F NMR resonances.

A series of doubly charged structure-directing agents based on two methylimidazolium moieties linked by a linear bridge of n = 3,4,5, or 6 methylene groups has been used in the synthesis of pure silica zeolites in the presence of fluoride. All of them yielded zeolite TON while only the one with n = 4 was able to produce also zeolite MFI at highly concentrated conditions. In this MFI zeolite, two distinct (19)F MAS NMR resonances with about equal intensity were observed, indicating two different chemical environments for occluded fluoride.

Zeolite synthesis in fluoride media: structure direction toward ITW by small methylimidazolium cations.

Pure silica ITW zeolite can be synthesized using 1,2,3-trimethylimidazolium and 1,3-dimethylimidazolium cations and fluoride anions as structure-directing agents (SDAs). Similarly to the previously reported 1,3,4-trimethylimidazolium, the dimethyl cation can also produce the zeolite TON, but this higher framework density phase finally transforms in situ into ITW. The structures of the as-made and calcined phases prepared with the new cations show a unit cell doubling along z, and the refined structures are reported.