Studies On Preparation, Characterization And Application Of A Novel Fe/Cr-Si-Pillared Montmorillonite Catalyst

As a novel porous material, pillared montmorillonite (PILM) is one of hotspots for mineral material research. Because of its big surface-to-volume ratio, variable apertures and strong acidity, PILM can be used as an excellent adsorbent and catalyst in petrochemical and environmental protection fields, and catch many scientist's attention in recent years.The properties, preparation technique, characterization method, pillaring mechanism and applications of PILM were summarized, and some questions (including thermal stability, and hydro-thermal stability, and pore structure et al) about PILM were pointed out in this paper. Calcium montmorillonite (Ca-M) was prepared by purifying LeXi bentonite with wet method two times. After purification, sodium modification of Ca-M was studied. A series of Fe/Cr-pillared montmorillonites (Fe/Cr-PILM) were prepared with conventional method using sodium montmorillonite (Na-M) as experimental materials, and synthesis condition of Fe/Cr-PILM was studied and optimized. In order to shorten the preparation cycle of PILM by overleaping the step of sodium modification of Ca-M, the pretreatment technique for Ca-M has been pointed out for the first time. A series of PILMs were prepared with hydrothermal method using pretreated Ca-M as starting materials, which show that pretreatment of Ca-M is feasible. Two times hydrolyzation of Fe³⁺ and Cr³⁺ was firstly pointed out in the process of pillar preparation with hydrothermal method. In order to improve the thermal stability, Fe/Cr-Si-pillaring agent solution was synthesized by hydrolyzing Fe³⁺ and Cr³⁺ solution on the surface of silica sol, and Fe/Cr-Si-pillared montmorillonite (Fe/Cr-Si-PILM) was prepared with conventional method and hydrothermal method. Because the technical innovation of preparation is the best way to improve the PILM properties, two novel methods (Microwave method and Ultrasonication method) have been studied to synthesize Fe/Cr-PILM.In order to expand PILM's new application in the field of coal conversion, catalytic activity of Fe/Cr-Si-PILM catalyst in LongKou lignite and ShenHua coal residue liquefaction was discussed and characterized in the last part of this paper.