Factors Affecting the Catalytic Performance of Zr,Al-Pillared Clays in the Synthesis of Propylene Glycol Methyl Ether

Abstract

Series of Al-, Ga-, and Zr,Al-pillared clays (Al-MM, Ga-MM, and Zr,Al-MM) were prepared through the intercalation of Al-, Ga-, and Zr-polyoxocations into three layered aluminosilicates with various textural properties and chemical compositions. Zr,Al-phases with the structure of bayerite–boehmite were also synthesized using Al and Zr oligomeric solutions, prepared from aluminum chloride and zirconium oxychloride, respectively, as metal sources, with Zr/Al ratios of 0–0.143. All materials were characterized by X-ray diffraction; elemental analysis; DR-UV–vis, FTIR, and 27Al MAS NMR spectroscopies; and N2 adsorption/desorption analysis. FTIR spectroscopy using pyridine, benzonitrile, and deuterated chloroform as probe molecules was used to investigate the acid–base properties of the solids. The catalytic performance of these materials was investigated in the synthesis of 1-methoxy-2-propanol from methanol and propylene oxide. It was found that the catalytic properties of Zr,Al-pillared clays depended on the textural properties (pore diameter), chemical composition (Si/Al molar ratio and Zr content), and type of Al salt (nitrate or chloride) used as the Al source for the preparation of the pillaring solution. The type of metal cation in the polyoxocations affected the reaction rate and isomer selectivity. Al-MM was found to exhibit a higher catalytic efficiency than Ga-MM and Zr-MM.

Tuning the Catalytic Performance of Novel Composites Based on ZIF‐8 and Nafen through Dimensional and Concentration Effects in the Synthesis of Propylene Glycol Methyl Ether

“…Keeping the data of the IR study of the ZIF‐8 catalyst in mind and reaction mechanisms in the presence of oxygen‐containing materials,, , , , we can suggest that the mechanism of the reaction between MeOH and PO in the presence of ZIF‐8 systems consists of the following steps:…”

“…Different catalytic systems relevant to this process are reported in the literature. These systems include alkaline catalysts (hydroxides of alkali and alkaline‐earth metals),, amino‐functionalized SiO 2 , immobilized ionic liquid 1,1,3,3‐tetramethylguanidinium lactate on bentonite and SBA‐15 (IL/Support),, M x O y (M – Cu, Fe, Zn, Sn, and Ni), MgO,, metal phosphate molecular sieves, Al‐, Ga‐, Zr‐, and Zr, Al‐pillared clays (PILCs), natural and synthetic layered double hydroxides (LDHs) …”

“…It is well established that the catalytic efficiency of oxygen‐containing materials is related to the nature of active sites, namely, “M n+ –O 2– ‐ Lewis acid site ‐ basic site” pairs, in the PGME synthesis. The optimal combination of the length of the M–O bond, the basicity of the oxygen ion and the strength of the metal ion are key parameters affecting the reaction rate and selectivity toward PGME.…”

Synthesis of core–shell Ce-modified mixed metal oxides derived from P123-templated layered double hydroxides

“…It is reported that a high strength of strong basic sites can lead to a strong stabilization of methoxide and propylene-like species which formed as intermediates on the surface of the solid and, in this way, hinder the process of reaction. 8 The element ratio of the catalyst and the reaction conditions were also studied. In Table 2, we investigated the element ratio of the catalyst and found that SiO 2 @Ce 0.33 Mg 2 A 1 -LDO(P123) has the best catalytic activity.…”

Reuse of Pillaring Agent in Sequential Bentonite Pillaring Processes

“…There are numerous oligomeric cations that could be used as pillars, as well as Al, Zr, Ti, Cr, Fe, Ce and others [ 1 , 3 , 4 ]. These cations could be used individually [ 2 , 5 , 6 , 7 , 8 ] or mixed [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. In addition, there is an enormous amount of work dealing with the use of Al-pillared clays as supports of metal nanoparticles (Pd and Pt, for example) for several catalytic applications [ 18 , 19 , 20 , 21 ].…”