Study On Synthesis Of New Type Mesoporous Material Directed By Rosin-based Quaternary Ammonium Salt

In 1992, highly-ordered mesoporous molecular sieves M41 S were firstly synthesized by the scientists of Mobil company using long chain quaternary ammonium salt as structure directing agent. Ever since then, anionic surfactant, nonionic surfactant and amphoteric surfactant have also been successfully applied as directing agent for the synthesis of mesoporous materials. Many kinds of mesoporous materials with novel structures were obtained. Surfactant properties(including shape, size, charge type, charge density, etc.) play a decisive role in the synthesis of mesoporous materials. Different kinds of surfactants will guide the reaction system to form materials with different mesostructures. Therefore, the work of exploring and developing new surfactants with special structures for the mesoporous materials synthesis has become the key way to the mesoporous materials innovation.In this paper, rosin-based quaternary ammonium salt was applied as directing agent for the synthesis of mesoporous materials. With the assistant of unique three-ring phenanthrene rigid skeleton, four types of mesoporous materials with new stuctures were synthesized. The obtained materials were characterized by X-ray diffraction, N2 adsorption-desorption and transmission electron microscopy to investigate the influence of different synthesis parameters on the material structures. Our work opened up the way to the mesopouous materials synthesis using non-long chain surfactant with big hydrophobic goup. The species of mesoporous materials were enriched, and the routes of synthesis of mesoporous materials were expanded. The achievements are listed as follows:Well-ordered 2D hexagonal mesoporous silica was synthesized in Na OH medium using TEOS as silica source and dehydroabietyltrimethyl ammonium bromide as structure directing agent. The pore size distribution was landed in the micro-mesoporous demarcation point(centered at 1.91 nm). The BET surface area was 1097.59 m2/g, the pore volume was 0.63 m3/g, and the pore wall thickness was 1.42 nm. In contrast with the classical 2D hexagonal mesoporous silica MCM-41, the material had a larger specific surface area, smaller pore size, and thinner pore wall. Highly-ordered 2D hexagonal mesoporous silica was synthesized using Na Si O3 as silica source. The pore size was centered at 2.03 nm. The BET surface area was 1229.15 m2/g, the pore volume was 0.59 m3/g, and the pore wall thickness was 1.25 nm.In contrast with the mesoporous silica synthesized using TEOS as silica source, the material had a larger specific surface area, bigger pore size, but thinner pore walls.Uniform mesoporous alumina was synthesized by ammonium carbonate precipitation using rosin-based trimethyl ammonium chloride as structure directing agent. The textural properties were improved by ammonia precipitation. Mesoporous alumina microfiber was synthesized by hydrothermal-homogeneous precipitation method using urea as precipitation agent. Based on the result that the precursor prepared by hydrothermal-homogeneous precipitation method was similar with the precursor prepared by ammonium carbonate precipitation, the modified ammonium carbonate precipitation-aging method was adopted for the synthesis of mesoporous alumina microfiber. The formation mechanism of fibrous morphology was investigated. The aging step was crucial for the formation of fibrous morphology. It was observed that the phase of the sample transformed from gibbsite into AACH with the increase of aging time. At the same time, well dispersed microfiber was obtained. Based on the result that γ-Al2O3 phase can be obtained under rather lower calcination temperature for the mesoporous alumina microfiber synthesized using rosin-based trimethyl ammonium chloride as structure directing agent, the hypothesis that Cl- can reduce the alumina phase transition temperature from AACH to γ-Al2O3 was proposed. In order to prove the hypothesis, different kinds of chloride were brought into the reaction system in the calcination step. The results indicated that the function of Cl- was truely acted after the decomposition of AACH into amorphous alumina. Hence, Cl- can reduce the alumina phase transition temperature from amorphous to γ-Al2O3.Zr(SO4)2/DTAB composite was successfully synthesized using Zr(SO4)2 as zirconia source and dehydroabietyltrimethyl ammonium bromide as structure directing agent. Tetragonal nanocrystalline mesoporous Zr O2 was synthesized by hydrothermal method in strong basic medium. The material had great thermal stability. The tetragonal nanocrystalline structure was synthesized by one step hydrothermal method in strong basic medium. In contrast with the process that first synthesis of amorphous zirconium hydrated hydroxide, and then dehydration and crystallization in high calcination temperature, strong basic condition hydrothermal method can effectively avoid the destruction resulted by dehydration and contraction of the pore wall in high temperature calcination. The materials possessed high surface area(107.34~242.02 m2/g), large pore volume(0.25~0.53 cm3/g) and big pore size(6.06~12.96 nm). Nanocrystalline mesoporous Zr O2 round-angle cube was synthesized by hydrothermal method using Zr OCl2 as zirconia source. The calcination temperature had great effect on the structure of the material. The grain size increased with the increase of calcination temperature. When the calcination temperature increased into 923 K, the sample possessed hollow ellipsoidal morphology.Ordered lamellar mesoporous titania was synthesized using peroxytitanate as titania source and dehydroabietyltrimethyl ammonium bromide as structure directing agent. Semicrystalline anatase uniform mesoporous titania was synthesized by evaporation induced self-assembling method using tetrabutyl titanate as titania source. The material possessed wormhole-like appearance without a long range packing order but with a fairly uniform pore size.Gas-phase dehydration of glycerol was investigated over WO3 catalysts synthesized with different kinds of mesoporous materials. Due to the high surface area and good hydrothermal stability, the mesoporous γ-Al2O3 microfiber supported WO3 catalyst showed high catalytic activity, good acrolein selectivity, and long catalytic life.