Synthesis of highly stable metal-containing extra-large-pore molecular sieves

Abstract

The isomorphic substitution of two different metals (Mg and Co) within the framework of the ITQ-51 zeotype (IFO structure) using bulky aromatic proton sponges as organic structure-directing agents (OSDAs) has allowed the synthesis of different stable metal-containing extra-large pore zeotypes with high pore accessibility and acidity. These metal-containing extra-large pore zeolites, named MgITQ-51 and CoITQ-51, have been characterized by different techniques, such as PXRD, SEM, EDX, UVVis spectroscopy, NH 3 -TPD, and FT-IR spectroscopy, to study their physico-chemical properties. The characterization confirms the preferential insertion of Mg and Co atoms within the crystalline structure of the ITQ-51 zeotype, providing high Brønsted acidity, and allowing their use as efficient heterogeneous acid catalysts in industrially-relevant reactions involving bulky organic molecules.

Summarizing comments on the discussion and a prospectus for urgent future action

“…As expected, Corma [3] gave us an elegant account not only of his work on preparing new catalysts with larger micropores than usual, and also of his use of Sn atoms as frameworksubstituted Lewis acid entities for cascade reactions, but, in addition, he discussed microporous zeotypes for the separation of gases, notably CH 4 from CO 2 and propene from propane. He also described the structure known as ITQ-37 solved by his Swedish colleagues and himself a few years ago [4].…”

“…Globally, however, the percentages of world energy uses in 2030 are expected to be as follows: In addition to these statistics, there are other relevant facts contained in the Technology Roadmap: Energy and Greenhouse Gases Reductions in the Chemical Industry via Catalytic Processes. 3 This report points out that the manufacture of 18 products (among thousands) from the chemical industry account for 80% of energy demand in the chemical industry and 75% of greenhouse gas emissions. 4 A key finding in this report is that improvements in catalytic and related processes could reduce energy intensity for these 18 products by 20-40% as a whole by 2050.…”

Exploiting the photophysical features of DMAN template in ITQ-51 zeotype in the search for FRET energy transfer

“…The Mg-containing ITQ-51 materials were prepared by hydrothermal method at 150 °C under static conditions. In the original recipe, the IFO structure was obtained after heating for 5 days; 51 in the present study, different heating times were applied (1–5 days) with the aim of reducing the thermal treatment time and hence minimizing the potential dye degradation. Crystallization of pure Mg-ITQ-51 was confirmed by PXRD (Fig.…”

“…The Mg-doped IFO zeotype was synthesized following the original recipe, 47,51 from gels with molar composition 0.95 Al 2 O 3 : 1.00 P 2 O 5 :0.1 MgO:1.2 DMAN:40 H 2 O, using DMAN as organic SDA and the divalent transition metal Mg 2+ ion as heteroatom to generate negative charges in the framework that will be balanced by protonated DMAN species. The high basicity of DMAN (pK a = 12.3) ensures its protonation in the synthesis medium (pH of the prepared gels is around 8), thus allowing the necessary organicinorganic interactions during the nucleation-crystallization processes.…”

“…If combined with proper acceptor dyes, artificial antenna systems could be developed by using this zeolite material. Of the different IFO materials available, 51 Mg-containing IFO (Mg-ITQ-51) was selected since we know from our previous works that doping these aluminophosphate zeolitic networks with Mg notably enhances the incorporation of cationic dyes because of electrostatic interactions. On the other hand, cationic dyes with proper size to be incorporated in the framework were selected with the aid of molecular simulations; the IFO extra-large pores enabled the incorporation for the first time in zeolite materials of very large laser dyes such as rhodamine 123 (R123) and Nile Blue (NB), with a general molecular structure built up by three fused aromatic rings (Fig.…”