| Pillared montmorillonite (PILM) is a kind of nano clay mineral materials with two-dimensional layered structure. The guest species(cations or molecules) are introduced into the interlayer of montmorillonite by ion exchange with the exchangeable cations between montmorillonite layers. This kind of clay mineral materials with large specific surface area, advanced pore structure and strong surface acidity.It has been widely used as adsorbent, catalyst and catalyst carrier in waste water treatment, air pollution control and catalysis of various chemical reactions. It has high research value and broad application prospects.In this paper, Calcium montmorillonite (Ca-Mt) from Inner Mongolia was used as raw material. Firstly, the hydrolysis characteristics of Fe3+ and Co2+ were studied. The preparation conditions of [Co(NH3)6]3+ as well as the stable coexistence conditions of polymeric hydroxyl iron cations and[Co(NH3)6]3+ were also studied. Fe/[Co(NH3)6]3+ co-pillared agent was prepared and Fe/[Co(NH3)6]3+-PILM was prepared based on the Fe/[Co(NH3)6]3+ co-pillared agent. It was discovered that the single[Co(NH3)6]3+ pillared agent and Fe/[Co(NH3)6]3+ co-pillared agent could not be introduced into the interlayer of Ca-Mt. After denying the possible experimental factors such as different Fe/Co molar ratios, pillaring temperature and types of montmorillonite materials, we proposed to employ the layer extending agents assisted preparation of Fe/[Co(NH3)6]3+-PILM. The effects of type and additive amount of the layer extending agents on the interlayer spacing of pillared montmorillonite were investigated. However, the results of XRD showed that the addition of the layer extending agents-glycerol did not achieve the goal of layer expansion: The interlayer spacing and thermal stability of Fe/[Co(NH3)6]3+-PILM could not meet the ideal requirements. It was concluded that the [Co(NH3)6]3+ might not be suitable as a pillared ion to prepare pillared montmorillonite. Therefore, the idea of using Fe/[Co(NH3)6]3+ co-pillared agent to prepare Fe/Co pillared montmorillonite was abandoned. Afterwards, 3-Aminopropyltriethoxysilane (KH-550) which belongs to the commonly used amino silane coupling agents was selected as a silicon pillar precursor to prepare the Fe/Co-Si-PILM. It was expected that the thermal stability of Fe/Co pillared montmorillonite can be significantly enhanced by the creation of silicon pillars in the interlayer spaces of montmorillonite.Our target was to obtain the pillared products with ideal interlayer spacing and thermal stability. N-(?-aminoethyl)-?-aminopropyltrimethoxysilane(KH-792) was also used as silicon pillars precursor in this work (controlled group) to find out the effects of aminosilane type on these PILM. The Fe/Co-Si-PILM were investigated by a combination of X-ray diffraction, elemental analysis, N2 adsorption-desorption, thermal analysis, NH3 temperature-programmed desorption and H2 temperature-programmed reduction capacity tests techniques. The results indicated that the complexes of Fe, Co and aminosilane were successfully intercalated into the interlayer space of montmorillonite .In addition, Fe/Co-Si-PILM which prepared by using KH-550 as silicon pillars precursor exhibited better interlayer spacing and thermal stability. When the calcination temperature up to 800?, the d(001) value of Fe/Co-Si1-PILM could be maintained at 1.59 nm. The optimum preparation conditions of Fe/Co-Si-PILM were following: the minimum amount of KH-550 was 6.0 CEC,n(Fe3++Co2+)/montmorillonite was 10mmol/g, the molar ratio of Fe/Co was 3:7. Under the optimum preparation conditions, the content of the active metal components Fe and Co in Fe/Co-Si1-PILM were 9.31% and 0.003%, respectively. The specific surface area was up to 198 m2/g, the total pore volume (Vtotal) and micropore volume (Vmic) were significantly improved and the surface acidity of montmorillonite was enhanced.In the end, the catalytic effect of Fe/Co-Si-PILM on liquefaction of Inner Mongolia lignite was studied, and the effect of Fe/Co-Si-PILM additive amount on coal liquefaction was investigated. Compared with the traditional 3%Fe2O3+1%S catalyst, Fe/Co-Si-PILM exhibited advantages in the process of coal liquefaction. In addition, the role of Fe/Co-Si-PILM in coal liquefaction was also discussed... |
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